Communication method, apparatus and system

Abstract

The present application relates to a communication method, an apparatus and a system. The method comprises: a first core network element receives first information from an IMS network element, the first information being used for instructing a first apparatus and a second apparatus to execute a call; and, according to the first information, the first core network element sends to a UPF first configuration information, the first configuration information being used for configuring the UPF to perform local exchange on call data between the first apparatus and the second apparatus, and both the first apparatus and the second apparatus accessing a network by means of a satellite. For example, the UPF may perform on the satellite exchange of the call data between the first apparatus and the second apparatus. Thus, call data can be exchanged on a satellite and does not need to be routed to a terrestrial network, thereby shortening the transmission path of call data and reducing the time delay.

Description

Communication method, device and system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Intellectual Property Office of the People's Republic of China on November 13, 2023, with application number 202311516601.3 and application name “A communication method, device and system”, the entire contents of which are incorporated by reference into this application; this application claims priority to the Chinese patent application filed with the Intellectual Property Office of the People's Republic of China on February 16, 2024, with application number 202410179021.8 and application name “A communication method, device and system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of communication technology, and in particular to a communication method, device, and system. Background Art

[0004] Currently, user equipment (UE) can make calls through the Internet Protocol (IP) Multimedia Subsystem (IMS). For example, the UE first registers with the network in the fifth generation (5G) system and establishes an IMS protocol data unit (PDU) session for carrying call data and call signaling. The above process mainly involves the interaction between the UE and the 5G core network (5G core, 5GC). After that, the UE initiates IMS registration with the IMS through the established IMS PDU session, establishes an IMS session, and then transmits voice data through the IMS session. This subsequent step involves the interaction between the UE and the IMS through the 5GC.

[0005] For satellite scenarios, UEs can access 4G and 5G networks via satellite, such as LTE NTN (Non-Terrestrial Networks) and 5G NTN. Depending on different satellite access scenarios, some network elements in the network can also be deployed on satellites, for example, base stations may be deployed on satellites. When a UE accesses a 5G network via satellite, if the UE conducts a call service through IMS, some network elements used to transmit call data may still be located on the ground, such as IMS network elements, so the call data needs to be routed from the satellite to the terrestrial network. Due to the long distance between the satellite and the terrestrial network, the latency increases.

[0006] Summary of the Invention

[0007] Embodiments of the present application provide a communication method, device, and system for reducing call delay.

[0008] In a first aspect, a first communication method is provided, which can be executed by a core network network element, or by other devices including the functions of a core network network element, or by a chip system (or, chip) or other functional module, which can realize the functions of a core network network element, and the chip system or functional module is, for example, arranged in a core network network element. The core network network element is, for example, a first core network network element. In the following description, the method is performed by the first core network element as an example. Optionally, the first core network element is, for example, an SMF, or other core network element capable of realizing similar functions. The method includes: receiving first information from an IMS network element, the first information being used to instruct a first device and a second device to perform a call; sending first configuration information to a UPF according to the first information, the first configuration information being used to configure the UPF to perform local switching of call data between the first device and the second device, wherein both the first device and the second device access the network via a satellite.

[0009] In an embodiment of the present application, the UPF can locally exchange call data between a first device and a second device based on first configuration information. Both the first device and the second device access the network via satellite. For example, the UPF can exchange call data between the first device and the second device on the satellite. Thus, call data can be exchanged on the satellite without having to be routed to the terrestrial network, shortening the call data transmission path and reducing latency. Furthermore, because the UPF can perform local exchange of call data between devices, the call data can directly reach the other end device from the UPF without having to be transmitted through network elements such as IMS network elements, further shortening the transmission path and reducing latency.

[0010] In an optional embodiment, the UPF is located on the satellite. If the UPF is located on the satellite, the UPF exchanges the call data between the first device and the second device locally, which is equivalent to exchanging the call data between the first device and the second device on the satellite, thereby reducing call latency.

[0011] In an optional embodiment, the first information further indicates that the first and second devices exchange call data via a satellite. Alternatively, the method further includes determining whether the first and second devices exchange call data via a satellite. Whether the call data between the first and second devices is exchanged via a satellite may be determined by an IMS network element, which may indicate the decision result to the first core network element via the first information. Alternatively, the first core network element may also determine whether the call data between the first and second devices is exchanged via a satellite. This allows for a flexible decision process.

[0012] In an optional embodiment, the method further includes: if the first information is also used to indicate that the first and second devices exchange call data on a satellite, determining that the first and second devices exchange call data on a satellite based on the first information; or determining that the first and second devices exchange call data on a satellite based on a UPF serving the first and second devices. Whether call data between the first and second devices are exchanged on a satellite can be determined by an IMS network element, which can indicate the decision result to the first core network element via the first information. Alternatively, whether call data between the first and second devices are exchanged on a satellite can also be determined by the first core network element. As can be seen, the decision-making process is relatively flexible.

[0013] In an optional embodiment, determining that the first and second devices are exchanging call data over a satellite includes: determining that the first and second devices are served by the same UPF; or determining that the first and second devices are served by different UPFs, where data transmission channels can be established between the different UPFs. If the first and second devices are served by the same UPF, the UPF can locally exchange call data between the first and second devices. If the first and second devices are served by different UPFs, but the different UPFs can communicate or establish a data transmission channel, call data between the two devices can also be locally exchanged through the two UPFs. Therefore, in both cases, the first and second devices can be considered capable of exchanging call data over a satellite.

[0014] In an optional embodiment, the first information further includes one or more of the following: a first identifier of the first device, a second identifier of the first device, address information of the first device, a first identifier of the second device, a second identifier of the second device, address information of the second device, calling information, called information, or descriptive information of call data between the first and second devices. The first information may include information related to the first device and / or information related to the second device, or may also include other information, without limitation.

[0015] In an optional embodiment, the description information of the call data is used by the UPF to perform one or more of the following settings: for call data from a communication device, setting a rule for filtering data to filter out call data between the first device and the second device, wherein the communication device is the first device or the second device; or, for call data from the communication device, setting a rule for forwarding data to forward to the UPF; or, for call data received by the UPF and forwarded by the UPF, setting the destination address of the call data to address information of a communication peer device, wherein if the call data comes from the first device, the communication peer device is the second device, or if the call data comes from the second device, the communication peer device is the first device; or, for call data received by the UPF and forwarded by the UPF, setting a rule for forwarding the call data to forward to the communication peer device. Through the above configuration process, the UPF can realize local switching of call data between the first device and the second device.

[0016] In a second aspect, a second communication method is provided, which can be executed by an IMS network element, or by other devices including IMS network element functions, or by a chip system (or, chip) or other functional module, the chip system or functional module can realize the functions of the IMS network element, and the chip system or functional module is, for example, set in the IMS network element. In the following description, the method is taken as an example of being executed by an IMS network element. Optionally, the IMS network element is, for example, a P-CSCF, or an S-CSCF, or it can also be other network elements within the IMS. The method includes: receiving a first request from a first device, the first request is used to request a call with a second device; sending first information to a first core network network element, the first information is used to instruct the first device and the second device to perform a call. For example, the first core network network element can refer to the first information to determine whether the first device and the second device exchange call data on the satellite, thereby, the call data can be exchanged on the satellite without being routed to the ground network, shortening the transmission path of the call data and reducing the delay.

[0017] In an optional implementation, the first information is further used to instruct the first device and the second device to exchange call data on a satellite.

[0018] In an optional embodiment, the method further includes: determining whether the first device and the second device exchange call data over a satellite. If an IMS network element determines whether the first device and the second device exchange data over a satellite, the IMS network element may determine whether the first device and the second device exchange call data over a satellite, and may thereby send the determination result to the first core network element.

[0019] In an optional embodiment, determining that the first device and the second device exchange call data over a satellite includes one or more of the following: determining that the first device and the second device are served by the same UPF, which is located on a satellite; or determining that the first device and the second device are served by the same IMS network element; or determining that the first device and the second device are served by different UPFs, both of which are located on a satellite; or determining that the media description information of the first device and the second device matches. If the first device and the second device are served by the same IMS network element, it can also be considered that the two devices are served by the same UPF, or by different UPFs. Therefore, the fact that the first device and the second device are served by the same IMS network element can also be used as a judgment condition for determining that the first device and the second device exchange call data over a satellite. In a traditional call process, when call data passes through the IMS, the IMS network element can perform format conversion on the call data. For example, the media description information of the UEs on both sides of the call may not match. Through processing by the IMS network element, the other end of the call can identify the received call data. In the embodiment of the present application, the call data between the first UE and the second UE can be transmitted directly to the call peer (the first UE or the second UE) without passing through the IMS. Therefore, the media description information of the first UE and the second UE can optionally match, thereby enabling the first UE and the second UE to identify the call data from the call peer without processing by the IMS network element. For other judgment conditions, please refer to the description of the effects of the first aspect or the corresponding embodiment.

[0020] In an optional embodiment, determining that the first device and the second device are served by the same IMS network element includes: determining, based on the second identifier of the second device carried in the first request, that the first device and the second device are served by the same IMS network element, and that the IMS network element uniquely corresponds to a single UPF. This is one method for determining whether the first device and the second device are served by the same IMS network element; other methods may also be used for determination, and are not specifically limited.

[0021] In an optional embodiment, determining, based on the second identifier of the second device carried in the first request, that the first device and the second device are served by the same IMS network element includes: determining, based on the second identifier of the second device and the second identifier of the first device, that both the first device and the second device perform IMS registration through the same IMS network element. For example, the IMS network element may store registration information of a UE, and the registration information of the UE may include the second identifier of the UE. Therefore, based on the second identifier of the UE, it is possible to determine whether the IMS network element stores the registration information of the UE, thereby determining whether the UE is registered with the IMS network element.

[0022] In an optional implementation, the second identifier of the second device includes a uniform resource locator of the second device and / or a uniform resource identifier of the second device.

[0023] In an optional implementation, the second identifier of the first device includes a uniform resource locator of the first device and / or a uniform resource identifier of the first device.

[0024] In an optional embodiment, determining that the first device and the second device are served by the same UPF includes: determining that the first request and the request from the second device originate from the same UPF. For example, if the source address information carried by the data packet corresponding to the first request and the source address information carried by the data packet corresponding to the request from the second UE are both the same address information, it can be determined that the requests from the two devices originate from the same UPF, thereby determining that the two devices are served by the same UPF. This determination method is relatively simple.

[0025] In an optional embodiment, determining that the first device and the second device exchange call data on a satellite includes: when the call between the first device and the second device corresponds to a delay processing strategy, determining that the first device and the second device exchange call data on a satellite; and / or, when a disaster recovery strategy is executed, determining that the first device and the second device exchange call data on a satellite. For example, if the current network has high requirements for latency and the call delay cannot be too long, a mechanism for exchanging call data on a satellite can be used to minimize the call delay. Alternatively, if a disaster is currently occurring, such as an earthquake or a tsunami, a mechanism for exchanging call data on a satellite can be used to allow emergency calls to be transmitted within a smaller delay to cope with emergencies.

[0026] In an optional embodiment, the method further includes one or more of the following: determining, based on the subscription information of the first device, that the network permits the first device's call data to be exchanged over a satellite, and / or determining, based on the subscription information of the second device, that the network permits the second device's call data to be exchanged over a satellite; or receiving second information indicating that the first device requests the first device's call data to be exchanged over a satellite, and / or indicating that the second device requests the second device's call data to be exchanged over a satellite; or receiving third information indicating that the network permits the first device's call data to be exchanged over a satellite, and / or indicating that the network permits the second device's call data to be exchanged over a satellite. For example, an IMS network element may obtain the device's subscription information to determine whether the network permits the devices to exchange call data over a satellite. For example, if the network does not permit the first device and / or the second device to exchange call data over a satellite, the IMS network element may decide not to exchange call data over a satellite with the first device and the second device to comply with network requirements. If the second information, for example, comes from the first device and / or the second device and represents a device requirement, the IMS network element may refer to the device requirement when making its decision. For example, if a first device requests that its call data be exchanged via a satellite, the IMS network element may attempt to determine that the first device's call data be exchanged via the satellite. The third information may come from another network element, such as a P-CSCF. The third information may come from an S-CSCF. For example, the S-CSCF obtains subscription information for the first device and / or the second device and determines, based on this subscription information, whether the network permits the first device and / or the second device to exchange call data via the satellite. The S-CSCF may then send the determination result to the P-CSCF, allowing the P-CSCF to refer to the determination result when making its decision, eliminating the need to determine, based on subscription information, whether the network permits the first device and / or the second device to exchange call data via the satellite. This reduces the workload of the P-CSCF.

[0027] In an optional embodiment, the call data is not transmitted through the IMS. For example, the call data can be directly exchanged in the UPF or other network elements (such as RAN) without passing through other network elements, shortening the call data transmission path and reducing transmission delay.

[0028] In a third aspect, a third communication method is provided. This method can be performed by a UPF, or by another device including UPF functionality, or by a chip system (or chip) or other functional module that can implement the functionality of a UPF. The chip system or functional module is, for example, provided in a UPF. In the following description, the method is performed by a UPF as an example. The method includes: receiving first configuration information; and performing local switching of call data between a first device and a second device according to the first configuration information configuration, wherein both the first device and the second device access a network via a satellite.

[0029] In an optional embodiment, the UPF is located on the satellite.

[0030] In an optional embodiment, local exchange of call data between the first device and the second device is performed according to the first configuration information configuration, including one or more of the following: for call data from a communication device, setting a rule for filtering data to filter out call data between the first device and the second device, wherein the communication device is the first device or the second device; or, for call data from the communication device, setting a rule for forwarding data to forward to the UPF; or, for call data received by the UPF and forwarded from the UPF, setting the destination address of the call data to the address information of the communication peer device, wherein, if the call data comes from the first device, the communication peer device is the second device, or, if the call data comes from the second device, the communication peer device is the first device; or, for call data received by the UPF and forwarded from the UPF, setting a rule for forwarding the call data to forward to the communication peer device.

[0031] Regarding the technical effects of the third aspect or various embodiments, reference may be made to the introduction to the technical effects of the first aspect or corresponding embodiments, and / or reference may be made to the introduction to the technical effects of the second aspect or corresponding embodiments.

[0032] In a fourth aspect, a fourth communication method is provided, which can be executed by a terminal device, or by other devices including the functions of a terminal device, or by a chip system (or, chip) or other functional module. The chip system or functional module can realize the functions of the terminal device, and the chip system or functional module is, for example, set in the terminal device. In the following description, the method is performed by a terminal device as an example. The terminal device is, for example, the first device or the second device described in any one or more of the aforementioned aspects. The method includes: sending second information to an IMS network element, where the second information is used to request the exchange of call data on a satellite.

[0033] Regarding the technical effects of the fourth aspect or various embodiments, reference may be made to the introduction to the technical effects of the first aspect or corresponding embodiments, and / or reference may be made to the introduction to the technical effects of the second aspect or corresponding embodiments.

[0034] In a fifth aspect, a fifth communication method is provided, which can be executed by an IMS network element, or by other devices including the functions of an IMS network element, or by a chip system (or, chip) or other functional module, which can realize the functions of the IMS network element, and the chip system or functional module is, for example, set in the IMS network element. In the following description, the method is taken as an example of being executed by an IMS network element. Optionally, the IMS network element is, for example, a P-CSCF, or an S-CSCF, or it can also be other network elements within the IMS. The method includes: receiving a first request from a first device, the first request being used to request a call with a second device, wherein both the first device and the second device access the network via a satellite; determining that the first device and the second device exchange call data on the satellite; sending the address information of the second device to the first device, and sending the address information of the first device to the second device. Optionally, the address information of the first device and the address information of the second device are used to exchange the call data on the satellite.

[0035] The UPF in the embodiment of the present application can locally exchange call data between a first device and a second device, both of which access the network via a satellite. For example, the UPF can exchange call data between the first device and the second device on a satellite. Thus, call data can be exchanged on a satellite without having to be routed to a terrestrial network, shortening the transmission path of the call data and reducing latency. Because the UPF can perform local exchange of call data between devices, the call data can directly reach the other-end device from the UPF without having to be transmitted through network elements such as IMS network elements, further shortening the transmission path and reducing latency. In addition, the IMS network element can send the address information of the devices on both sides of the call to the communication peer device, so that the devices on both sides of the call can carry the address of the other-end device during the call to exchange call data on the satellite, eliminating the need for excessive configuration of core network elements and / or RAN, reducing the network element configuration process and improving call efficiency.

[0036] In an optional embodiment, the method further includes: receiving a registration request from a communication device, wherein a message header of the registration request includes address information of the communication device, and the communication device includes the first device or the second device. When registering, the communication device may send the address information of the communication device to the IMS network element, so that the IMS network element can obtain the address information of the communication device from the registration request of the communication device.

[0037] In an optional embodiment, determining that the first device and the second device exchange call data on a satellite includes: determining that the first device and the second device are served by the same UPF, and the UPF is located on the satellite; and / or determining that the first device and the second device are served by the same IMS network element.

[0038] In an optional implementation, determining that the first device and the second device exchange call data on a satellite further includes: determining that media description information of the first device and the second device matches.

[0039] In an optional implementation, determining that the first device and the second device are served by the same IMS network element includes: determining that the first device and the second device are served by the same IMS network element according to the second identifier of the second device carried in the first request.

[0040] In an optional embodiment, determining that the first device and the second device are served by the same IMS network element based on the second identifier of the second device carried in the first request includes: determining that the first device and the second device both perform IMS registration through the same IMS network element based on the second identifier of the second device and the second identifier of the first device.

[0041] In an optional implementation, the second identifier of the second device includes a uniform resource locator of the second device and / or a uniform resource identifier of the second device.

[0042] In an optional implementation, the second identifier of the first device includes a uniform resource locator of the first device and / or a uniform resource identifier of the first device.

[0043] In an optional embodiment, determining that the first device and the second device are served by the same UPF includes: determining that the first request and the request from the second device come from the same UPF.

[0044] In an optional embodiment, determining that the first device and the second device exchange call data on a satellite includes: when the call between the first device and the second device corresponds to a delay processing strategy, determining that the first device and the second device exchange call data on a satellite; and / or, when a disaster recovery strategy is executed, determining that the first device and the second device exchange call data on a satellite.

[0045] In an optional embodiment, the method further includes one or more of the following: determining, based on the contract information of the first device, that the network allows the call data of the first device to be exchanged on the satellite, and / or determining, based on the contract information of the second device, that the network allows the call data of the second device to be exchanged on the satellite; or, receiving second information, wherein the second information is used to indicate that the first device requests the call data of the first device to be exchanged on the satellite, and / or, indicates that the second device requests the call data of the second device to be exchanged on the satellite; or, receiving third information, wherein the third information is used to indicate that the network allows the call data of the first device to be exchanged on the satellite, and / or, indicates that the network allows the call data of the second device to be exchanged on the satellite.

[0046] In an optional implementation, the call data is not transmitted via the IMS.

[0047] Regarding the technical effects of the fifth aspect or various embodiments, reference may be made to the introduction to the technical effects of the first aspect or corresponding embodiments, and / or reference may be made to the introduction to the technical effects of the second aspect or corresponding embodiments.

[0048] In the sixth aspect, a sixth communication method is provided, which can be executed by a terminal device, or by other devices including the functions of a terminal device, or by a chip system (or, chip) or other functional module, which can realize the functions of the terminal device, and the chip system or functional module is, for example, set in the terminal device. In the following introduction, the method is taken as an example of being executed by a terminal device. The terminal device is, for example, the first device or the second device described in any one or more of the aforementioned aspects. The method includes: receiving a second request from an IMS network element, the second request including address information of the second device, wherein the first device is a calling device and the second device is a called device, or the first device is a called device and the second device is a calling device, and both the first device and the second device access the network via a satellite; sending call data to the UPF, the destination address information of the call data is the address information of the second device. Optionally, the address information of the second device is used to exchange the call data on the satellite.

[0049] In an optional implementation, the method further includes: sending second information to the IMS network element, where the second information is used to instruct the communication device to request that the call data of the communication device be exchanged on a satellite.

[0050] In an optional embodiment, the method further includes: sending a registration request to the IMS network element, the registration request being used to request registration to the IMS network element (or requesting to perform IMS registration, or requesting to register to the IMS where the IMS network element is located), wherein the registration request is also used to instruct the communication device to access the network via a satellite.

[0051] Regarding the technical effects of the sixth aspect or various implementations, reference may be made to the introduction to the technical effects of the fifth aspect or corresponding implementations.

[0052] In the seventh aspect, a seventh communication method is provided, which can be executed by an IMS network element, or by other devices including the functions of an IMS network element, or by a chip system (or, chip) or other functional module, which can realize the functions of the IMS network element, and the chip system or functional module is, for example, arranged in an IMS network element. In the following introduction, taking the method being executed by the first IMS network element as an example, the IMS network element is, for example, the first IMS network element or the second IMS network element. Optionally, the IMS network element is, for example, a P-CSCF, or an S-CSCF, or it can also be other network elements within the IMS. The method includes: receiving a first message, where the first message is used by a first device to request a call with a second device, or for the second device to respond to a call request from the first device; based on a first condition, determining that the first device and the second device are allowed to exchange call data on a satellite; and sending a second message to a second core network element, where the second message includes an identifier of the first device, an identifier of the second device, and fourth information, where the fourth information is used to request the first device and the second device to exchange call data on a satellite. The second core network element is a second core network element that serves an IMS PDU session for the first device and / or the second device.

[0053] The UPF in the embodiment of the present application can locally exchange call data between the first device and the second device. Both the first device and the second device access the network via a satellite. For example, the UPF can exchange call data between the first device and the second device on the satellite. As a result, call data can be exchanged on the satellite without having to be routed to the ground network, shortening the transmission path of the call data and reducing latency. Since the UPF can perform local exchange of call data between devices, the call data can directly reach the call peer device from the UPF without having to be transmitted through network elements such as the IMS network element, further shortening the transmission path and reducing latency. In addition, the IMS network element can make a corresponding judgment on whether the first device and the second device can exchange call data on the satellite, so that the first device and the second device can exchange call data on the satellite if the conditions are met, which meets the requirements of communication scenarios and various communication parameters.

[0054] In an optional embodiment, the first condition includes one or more of the following: allowing the first device and / or the second device to exchange call data on the satellite; the first device and the second device are served by the same user plane function entity, and the same user plane function entity is deployed on the satellite; the first device and the second device are served by the same IMS network element; the first device and the second device are served by different user plane function entities, and the different user plane function entities are both deployed on the satellite; the media description information used by the first device and the second device matches; the service PLMN of the first device is the same as the service PLMN of the second device; the first device and the second device are located under the same satellite; the first device and the second device are located under different satellites, and there is an inter-satellite link between the different satellites; lawful interception of the call is not performed; when at least one of the first device or the second device accesses a roaming network, the device accessing the roaming network does not perform home routing in the call; the IMS PDU session of the first device and the IMS PDU session of the second device are served by the same second core network element; or, the IMS PDU session of the first device and the IMS PDU session of the second device are served by the same second core network element and the same first core network element. Alternatively, the first condition may also include other conditions, which is not limited.

[0055] In an optional embodiment, the method further includes: obtaining information about a second core network element serving the IMS PDU session of the first device, and / or obtaining information about a second core network element serving the IMS PDU session of the second device; or obtaining information about the second core network element and the first core network element serving the IMS PDU session of the first device, and / or obtaining information about the second core network element and the first core network element serving the IMS PDU session of the second device. For example, if the first IMS network element wants to determine whether the IMS PDU session of the first device and the IMS PDU session of the second device are served by the same second core network element, information about the second core network element serving the IMS PDU sessions of the two devices may be obtained to determine whether the two second core network elements are the same core network element. For another example, if the first IMS network element wants to determine whether the IMS PDU session of the first device and the IMS PDU session of the second device are served by the same first core network element, information about the second core network element serving the IMS PDU sessions of the two devices may be obtained to determine whether the two first core network elements are the same core network element.

[0056] In an optional embodiment, the method further includes: sending at least one of the following to a second IMS network element serving the second device: indication information, the indication information being used to instruct the first device and the second device to exchange call data over a satellite; information about a user plane functional entity serving the first device; information about a serving PLMN for the first device; an identifier of a satellite serving the first device; an identifier of a serving cell for the first device; information about a second core network element serving an IMS PDU session for the first device; or information about a first core network element serving an IMS PDU session for the first device. If the first IMS network element and the second IMS network element serving the second device are different network elements, the first IMS network element may send the above information to the second IMS network element, so that the first and second IMS network elements can maintain consistency in their decisions regarding whether the first and second devices exchange call data over a satellite.

[0057] In an optional embodiment, sending at least one of the following items to a second IMS network element serving the second device includes: when the first device accesses a network via a satellite and / or allows the first device to exchange call data via a satellite, sending at least one of the following items to the second IMS network element. For example, the first IMS network element may send the above information to the second IMS network element if the first device and the second device are allowed to exchange call data via a satellite. If the first IMS network element does not allow the first device and the second device to exchange call data via a satellite, the first IMS network element may not send the above information to the second IMS network element, thereby reducing the interaction process between the network elements.

[0058] In an optional embodiment, the method further includes receiving confirmation information from the second IMS network element, the confirmation information being used to confirm that the first device and the second device are exchanging call data over the satellite. After receiving the information from the first IMS network element, the second IMS network element may send a confirmation information to the first IMS network element if the first device and the second device are permitted to exchange call data over the satellite. Through this interaction, the first and second IMS network elements can maintain a consistent decision regarding whether the first device and the second device are to exchange call data over the satellite.

[0059] In an optional embodiment, the method also includes: receiving at least one of the following items from the first IMS network element: indication information, the indication information is used to instruct the first device and the second device to exchange call data on the satellite; information of the user plane functional entity serving the first device; information of the service PLMN of the first device; an identifier of the satellite serving the first device; an identifier of the service cell of the first device; information of the second core network element serving the IMS PDU session of the first device; or information of the first core network element serving the IMS PDU session of the first device.

[0060] In an optional implementation, the method further includes: sending confirmation information to the first IMS network element, where the confirmation information is used to confirm that the first device and the second device exchange call data on the satellite.

[0061] In an optional embodiment, sending confirmation information to the first IMS network element includes: sending the confirmation information to the first IMS network element when at least one of the following is satisfied: the second device is allowed to exchange call data on the satellite; the first device and the second device are served by the same user plane function entity, and the same user plane function entity is deployed on the satellite; the first device and the second device are served by different user plane function entities, and the different user plane function entities are both deployed on the satellite; the media description information used by the first device and the second device matches; the service PLMN of the first device is the same as the service PLMN of the second device; the first device and the second device are located under the same satellite; the first device and the second device are located under different satellites, and there is an inter-satellite link between the different satellites; lawful interception of the call of the second device is not performed; the second core network network element serving the IMS PDU session of the first device is the same as the second core network network element serving the IMS PDU session of the second device; or the second core network network element serving the IMS PDU session of the first device is the same as the second core network network element serving the IMS PDU session of the second device, and the first core network network element serving the IMS PDU session of the first device is the same as the IMS PDU session of the second device. The first core network element of the PDU session is the same.

[0062] In an optional embodiment, the method further includes: receiving seventh information from the second core network element, the seventh information being used to indicate a configuration result for exchanging call data between the first and second devices over a satellite. The second core network element serving the first or second device may send the seventh information to the IMS network element, so that the IMS network element can ascertain the configuration result of the second core network element for exchanging call data between the first and second devices over a satellite.

[0063] In an optional implementation, the first device is a calling device of the call, and the second device is a called device of the call.

[0064] In an eighth aspect, an eighth communication method is provided. The method can be performed by a second core network element, or by other devices including the functions of the second core network element, or by a chip system (or chip) or other functional module. The chip system or functional module can implement the functions of the second core network element. The chip system or functional module is, for example, set in the second core network element. In the following description, the method is performed by the second core network element as an example. The second core network element is, for example, a PCF. The method includes: receiving a second message, the second message including an identifier of a first device, an identifier of a second device, and fourth information, the fourth information being used to request the first device and the second device to exchange call data on a satellite; based on a second condition, sending fifth information to a first core network element serving the first device, the fifth information being used to instruct the first device and the second device to exchange call data on a satellite, wherein the first core network element serving the first device also serves the second device, or the first core network element serving the first device does not serve the second device.

[0065] The UPF in the embodiment of the present application can locally exchange call data between the first device and the second device. Both the first device and the second device access the network via a satellite. For example, the UPF can exchange call data between the first device and the second device on the satellite. As a result, call data can be exchanged on the satellite without having to be routed to the ground network, shortening the transmission path of the call data and reducing latency. Since the UPF can perform local exchange of call data between devices, the call data can directly reach the call peer device from the UPF without having to be transmitted through network elements such as the IMS network element, further shortening the transmission path and reducing latency. In addition, the PCF can make a corresponding judgment on whether the first device and the second device can exchange call data on the satellite, so that the first device and the second device can exchange call data on the satellite if the conditions are met, which meets the requirements of communication scenarios and various communication parameters.

[0066] In an optional embodiment, the first core network element serving the first device does not serve the second device, and the method further includes: sending sixth information to the first core network element serving the second device, the sixth information being used to instruct the first device and the second device to exchange call data over the satellite. If the first core network elements serving the first device and the second device are different, the second core network element may send information to each of the two first core network elements to instruct the first device and the second device to exchange call data over the satellite.

[0067] In an optional embodiment, the second condition includes one or more of the following: the second core network element serving the IMS PDU session of the first device is the same as the second core network element serving the IMS PDU session of the second device; the first core network element serving the IMS PDU session of the first device is the same as the first core network element serving the IMS PDU session of the second device; both the first device and the second device access the network via a satellite; determining that the first device and the second device are located on the same satellite; or determining that the first device and the second device are located on different satellites and that there is an inter-satellite link between the different satellites. Alternatively, the second condition may also include other conditions, which are not limited to this.

[0068] In an optional embodiment, the method further includes: receiving a third message, the third message including an identifier of the first device, an identifier of the second device, and the fourth information; and sending fifth information to a first core network element serving the first device based on a second condition, including: sending the fifth information to the first core network element serving the first device based on the second condition, the second message, and the third message. For example, if the second core network element serving the first device and the second device is the same, the core network element may send the fifth information, or send the fifth information and the sixth information, after the second condition is met and after receiving the second message and the third message.

[0069] In an optional embodiment, the method further includes: determining that a second core network element serving the IMS PDU session of the first device is different from a second core network element serving the IMS PDU session of the second device, and / or that a first core network element serving the IMS PDU session of the first device is different from a first core network element serving the IMS PDU session of the second device; and sending first rejection information to the IMS network element, where the first rejection information is used to indicate rejection of exchanging call data between the first device and the second device on the satellite. For example, the second core network element may send the first rejection information to the IMS network element if one or more of the following conditions are met: the second condition is not met, the second message is not received, or the third message is not received.

[0070] In an optional embodiment, the method further includes: receiving eighth information from a first core network element serving an IMS PDU session of the first device, the eighth information indicating a configuration result for exchanging call data between the first device and the second device over a satellite; and sending seventh information to the IMS network element, the seventh information indicating a configuration result for exchanging call data between the first device and the second device over a satellite. For example, after receiving the eighth information from the first core network element, the second core network element may send the configuration result to the IMS network element.

[0071] In an optional embodiment, before sending the eighth information to the IMS network element, the method further includes: receiving ninth information from a first core network element serving the IMS PDU session of the second device, the ninth information indicating a configuration result for exchanging call data between the first and second devices over a satellite. If the second core network element serving the first and second devices is the same, the second core network element may send the configuration result to the IMS network element after receiving the eighth and ninth information from the two first core network elements.

[0072] In a ninth aspect, a ninth communication method is provided, which may be executed by a first core network element, or by other devices including the functions of the first core network element, or by a chip system (or chip) or other functional module, wherein the chip system or functional module can realize the functions of the first core network element, and the chip system or functional module is, for example, arranged in the first core network element. In the following description, the method is taken as an example in which the first core network element is executed. The first core network element is, for example, an SMF. The method includes: receiving information from a second core network element, wherein the information is used to instruct the first device and the second device to exchange call data on a satellite; based on a third condition, sending third configuration information to a first user plane function entity, wherein the third configuration information is used to configure the first user plane function entity to directly forward call data between the first device and the second device, the first user plane function entity being deployed on a satellite, the first user plane function entity serving the first device, or the first user plane function entity serving the first device and the second device.

[0073] The UPF in the embodiment of the present application can locally exchange call data between the first device and the second device. Both the first device and the second device access the network via a satellite. For example, the UPF can exchange call data between the first device and the second device on the satellite. As a result, call data can be exchanged on the satellite without having to be routed to the ground network, shortening the transmission path of the call data and reducing latency. Since the UPF can perform local exchange of call data between devices, the call data can directly reach the call peer device from the UPF without having to be transmitted through network elements such as the IMS network element, further shortening the transmission path and reducing latency. In addition, the SMF can make corresponding judgments on whether the first device and the second device can exchange call data on the satellite, so that the first device and the second device can exchange call data on the satellite if the conditions are met, which meets the requirements of communication scenarios and various communication parameters.

[0074] In an optional embodiment, the first user plane function entity serves the first device, and the method further includes: sending fourth configuration information to a second user plane function entity, the fourth configuration information being used to configure the second user plane function entity to directly forward call data between the first device and the second device, the second user plane function entity being deployed on a satellite, and the second user plane function entity serving the second device. If the UPFs serving the first and second devices are different, the first core network element may send configuration information to each of the two UPFs to configure each of the two UPFs.

[0075] In an optional embodiment, the third condition includes one or more of the following: the first device and the second device both access the network via a satellite; the first device and the second device are served by the same user plane function entity, which is deployed on a satellite; the first device and the second device are served by different user plane function entities, which are both deployed on a satellite and can establish a data transmission channel; the first device and the second device are located on the same satellite; or the first device and the second device are located on different satellites, and an inter-satellite link exists between the different satellites. Alternatively, the third condition may include other conditions, which are not limited to this.

[0076] In a tenth aspect, a communication device is provided. The communication device may be the first core network element described in any one of the first to ninth aspects. The communication device possesses the functions of the first core network element. The communication device may be, for example, the first core network element, or a larger device including the first core network element, or a functional module within the first core network element, such as a baseband device or a system-on-chip. In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). The transceiver unit is capable of performing both transmitting and receiving functions. When the transceiver unit performs the transmitting function, it may be referred to as a transmitting unit (sometimes also referred to as a transmitting module); when the transceiver unit performs the receiving function, it may be referred to as a receiving unit (sometimes also referred to as a receiving module). The transmitting unit and the receiving unit may be the same functional module, referred to as a transceiver unit, which is capable of both transmitting and receiving functions. Alternatively, the transmitting unit and the receiving unit may be different functional modules, with the transceiver unit being a collective term for these functional modules.

[0077] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive first information from an IMS network element, where the first information is used to instruct the first device and the second device to perform a call; the transceiver unit (or, the sending unit) is used to send first configuration information to the UPF based on the first information, where the first configuration information is used to configure the UPF to perform local switching of call data between the first device and the second device, wherein both the first device and the second device access the network via satellite.

[0078] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive information from a second core network network element, and the information is used to instruct the first device and the second device to exchange call data on the satellite; the transceiver unit (or, the sending unit) is used to send third configuration information to the first user plane function entity based on a third condition, and the third configuration information is used to configure the first user plane function entity to directly forward call data between the first device and the second device. The first user plane function entity is deployed on the satellite, and the first user plane function entity serves the first device, or the first user plane function entity serves the first device and the second device.

[0079] In an optional embodiment, the communication device also includes a storage unit (sometimes also referred to as a storage module), and the processing unit is used to couple with the storage unit and execute the program or instructions in the storage unit, enabling the communication device to perform the functions of the first core network network element described in any one of the first to sixth aspects above.

[0080] In the eleventh aspect, a communication device is provided. The communication device may be the IMS network element described in any one of the first to ninth aspects. The communication device has the functions of the above-mentioned IMS network element. The communication device is, for example, an IMS network element, or a larger device including an IMS network element, or a functional module in an IMS network element, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). For the implementation of the transceiver unit, please refer to the introduction of the tenth aspect.

[0081] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive a first request from a first device, and the first request is used to request a call with a second device; the transceiver unit (or, the sending unit) is used to send first information to a first core network element, and the first information is used to instruct the first device and the second device to perform a call.

[0082] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive a first request from a first device, the first request being used to request a call with a second device, wherein both the first device and the second device access a network via a satellite; the processing unit is used to determine that the first device and the second device exchange call data on the satellite; the transceiver unit (or, the sending unit) is used to send the address information of the second device to the first device, and to send the address information of the first device to the second device.

[0083] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive a first message, where the first message is used by the first device to request a call with the second device, or for the second device to respond to the call request from the first device; the processing unit is used to determine, based on a first condition, whether the first device and the second device are allowed to exchange call data on the satellite; the transceiver unit (or, the sending unit) is used to send a second message to a second core network network element, where the second message includes an identifier of the first device, an identifier of the second device, and fourth information, where the fourth information is used to request the first device and the second device to exchange call data on the satellite, and the second core network network element is a second core network network element that serves the IMS PDU session of the first device and / or the second device.

[0084] In an optional embodiment, the communication device further includes a storage unit (sometimes also referred to as a storage module), and the processing unit is used to couple with the storage unit and execute the program or instructions in the storage unit, enabling the communication device to perform the functions of the IMS network element described in any one of the first to sixth aspects above.

[0085] In the twelfth aspect, a communication device is provided. The communication device may be the UPF described in any one of the first to ninth aspects above. The communication device has the functions of the above-mentioned UPF. The communication device is, for example, a UPF, or a larger device including a UPF, or a functional module in a UPF, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). For the implementation of the transceiver unit, please refer to the introduction of the tenth aspect.

[0086] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive first configuration information; the processing unit is used to perform local switching of call data between the first device and the second device according to the first configuration information configuration, wherein both the first device and the second device access the network via a satellite.

[0087] In an optional embodiment, the communication device further includes a storage unit (sometimes also referred to as a storage module), and the processing unit is used to couple with the storage unit and execute the program or instructions in the storage unit, enabling the communication device to perform the functions of the IMS network element described in any one of the first to sixth aspects above.

[0088] In the thirteenth aspect, a communication device is provided. The communication device may be the first device or the second device described in any one of the first to ninth aspects. The communication device has the functions of the first device or the second device. The communication device is, for example, the first device or the second device, or a larger device including the first device or the second device, or a functional module in the first device or the second device, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). For the implementation of the transceiver unit, reference may be made to the introduction of the tenth aspect.

[0089] In an optional implementation, the transceiver unit (or the receiving unit) is configured to send second information to the IMS network element, where the second information is used to instruct the terminal device to request that call data of the terminal device be exchanged on a satellite.

[0090] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive a second request from the IMS network element, the second request including address information of the second device, wherein the first device is a calling device and the second device is a called device, or the first device is a called device and the second device is a calling device, and both the first device and the second device access the network via a satellite; the transceiver unit (or, the sending unit) is used to send call data to the UPF, and the destination address information of the call data is the address information of the second device.

[0091] In an optional embodiment, the communication device also includes a storage unit (sometimes also referred to as a storage module), and the processing unit is used to couple with the storage unit and execute the program or instructions in the storage unit, enabling the communication device to perform the functions of the first device or the second device described in any one of the first to sixth aspects above.

[0092] In the fourteenth aspect, a communication device is provided. The communication device may be the second core network element described in any one of the first to ninth aspects. The communication device has the functions of the second core network element. The communication device is, for example, a second core network element, or a larger device including a second core network element, or a functional module in a second core network element, such as a baseband device or a chip system. In an optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also referred to as a processing module) and a transceiver unit (sometimes also referred to as a transceiver module). For the implementation of the transceiver unit, reference may be made to the introduction of the tenth aspect.

[0093] In an optional embodiment, the transceiver unit (or, the receiving unit) is used to receive a second message, where the second message includes an identifier of the first device, an identifier of the second device, and fourth information, and the fourth information is used to request the first device and the second device to exchange call data on the satellite; the transceiver unit (or, the sending unit) is used to send fifth information to the first core network element serving the first device based on a second condition, and the fifth information is used to instruct the first device and the second device to exchange call data on the satellite, wherein the first core network element serving the first device also serves the second device, or the first core network element serving the first device does not serve the second device.

[0094] In an optional embodiment, the communication device also includes a storage unit (sometimes also referred to as a storage module), and the processing unit is used to couple with the storage unit and execute the program or instructions in the storage unit, enabling the communication device to perform the functions of the second core network network element described in any one of the first to ninth aspects above.

[0095] In a fifteenth aspect, a communications device is provided. The communications device may be a first core network element, or a chip or chip system used in the first core network element. The communications device includes a communications interface and a processor, and optionally, a memory. The memory is configured to store a computer program. The processor is coupled to the memory and the communications interface. When the processor reads the computer program or instructions, the communications device executes the method performed by the first core network element in each of the above aspects.

[0096] In a sixteenth aspect, a communication device is provided. The communication device may be an IMS network element, or a chip or chip system used in an IMS network element. The communication device includes a communication interface and a processor, and optionally, a memory. The memory is configured to store a computer program. The processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, the communication device executes the method performed by the IMS network element in each of the above aspects.

[0097] In a seventeenth aspect, a communication device is provided. The communication device may be a UPF, or a chip or chip system used in a UPF. The communication device includes a communication interface and a processor, and optionally, a memory. The memory is used to store a computer program. The processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, the communication device executes the methods performed by the UPF in the above aspects.

[0098] In aspect 18, a communication device is provided, which may be a terminal device, or a chip or chip system used in a terminal device. The communication device includes a communication interface and a processor, and optionally, a memory. Optionally, the terminal device is, for example, the first device or the second device described in any one or more of the above aspects. The memory is used to store a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, the communication device executes the method performed by the first device or the second device in the above aspects.

[0099] In a nineteenth aspect, a communications device is provided. The communications device may be a second core network element, or a chip or chip system used in the second core network element. The communications device includes a communications interface and a processor, and optionally, a memory. The memory is configured to store a computer program. The processor is coupled to the memory and the communications interface. When the processor reads the computer program or instructions, the communications device executes the method performed by the second core network element in each of the above aspects.

[0100] In a twentieth aspect, a communications system is provided, comprising a first core network element and an IMS network element, wherein the first core network element is configured to execute the method performed by the first core network element as described in any one of the first to fourth aspects, and the IMS network element is configured to execute the method performed by the IMS network element as described in any one of the first to fourth aspects. For example, the first core network element may be implemented by the communications apparatus described in the tenth or fifteenth aspect, and the IMS network element may be implemented by the communications apparatus described in the eleventh or sixteenth aspect.

[0101] Optionally, the communication system further includes a UPF, which is configured to execute the method performed by the UPF as described in any one of the first to fourth aspects. For example, the UPF can be implemented by the communication device described in the twelfth or seventeenth aspect.

[0102] Optionally, the communication system further includes a terminal device configured to execute the method performed by the first device or the second device as described in any one of the first to fourth aspects. For example, the terminal device may be implemented by the communication device described in the thirteenth or eighteenth aspect.

[0103] In a twenty-first aspect, another communication system is provided, comprising a first core network element, wherein the first core network element is configured to execute the method performed by the first core network element as described in any one of aspects 5 to 6. For example, the first core network element may be implemented by the communication apparatus described in aspect 10 or aspect 15.

[0104] Optionally, the communication system further includes a terminal device, the terminal device being configured to execute the method performed by the first device or the second device as described in any one of the fifth to sixth aspects above. For example, the terminal device may be implemented by the communication device described in the thirteenth or eighteenth aspect.

[0105] In a twenty-second aspect, another communication system is provided, comprising an IMS network element, wherein the IMS network element is configured to execute the method performed by the IMS network element as described in any one of aspects 6 to 9. For example, the IMS network element may be implemented by the communication device as described in aspect 11 or aspect 16.

[0106] Optionally, the communication system further includes a second core network element, which is configured to execute the method performed by the second core network element as described in any one of aspects 6 to 9. For example, the second core network element may be implemented by the communication device described in aspect 14 or aspect 19.

[0107] Optionally, the communication system further includes a first core network element, which is configured to execute the method performed by the first core network element as described in any one of aspects 6 to 9. For example, the first core network element may be implemented by the communication device described in aspect 10 or aspect 15.

[0108] In the twenty-third aspect, a computer-readable storage medium is provided, which is used to store computer programs or instructions. When it is executed, the method executed by the first core network element or the second core network element or the IMS network element or the UPF or the terminal device in the above aspects is implemented.

[0109] In a twenty-fourth aspect, a computer program product comprising instructions is provided, which, when executed on a computer, enables the methods described in the above aspects to be implemented.

[0110] In the twenty-fifth aspect, a chip or chip system is provided, comprising a processor and an interface, wherein the processor is used to call and execute instructions from the interface so that the chip or chip system implements the methods in the above aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] FIG1 is a schematic diagram of a transmission path of call data;

[0112] FIG2A is a schematic diagram of a 5G network architecture;

[0113] FIG2B is a schematic diagram of the IMS architecture;

[0114] 3A to 3E are schematic diagrams of several application scenarios of the embodiments of the present application;

[0115] 4A and 4B are two flow charts of a communication method provided in an embodiment of the present application;

[0116] FIG5A is a flow chart of another communication method provided in an embodiment of the present application;

[0117] 5B is a schematic diagram of source address information included in a data packet corresponding to a SIP message in an embodiment of the present application;

[0118] FIG6 is a schematic diagram of a device provided in an embodiment of the present application;

[0119] FIG7 is a schematic diagram of another device provided in an embodiment of the present application;

[0120] FIG8 is a flow chart of another communication method provided in an embodiment of the present application;

[0121] FIG9 is a flowchart of another communication method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0122] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0123] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plural" means two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. For example, A / B means: A or B. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0124] In the embodiments of this application, ordinal numbers such as "first" and "second" are used to distinguish multiple objects and are not used to limit the size, content, order, timing, priority, or importance of multiple objects. In addition, the numbering of steps in the various embodiments introduced in this application is only to distinguish different steps and is not used to define the order between steps. For example, S501 can occur before S502, or after S502, or at the same time as S502.

[0125] Below, some terms or concepts in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

[0126] In the embodiment of the present application, the terminal device is a device with wireless transceiver function, which can be a fixed device, a mobile device, a handheld device (such as a mobile phone), a wearable device, a vehicle-mounted device, or a wireless device built into the above device (such as a communication module, a modem, or a chip system, etc.). The terminal device is used to connect people, objects, machines, etc., and can be widely used in various scenarios, such as but not limited to the following scenarios: perception scenarios, cellular communications, device-to-device communication (D2D), vehicle to everything (V2X), machine-to-machine / machine-type communications (M2M / MTC), Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, drones, robots, indoor commercial scenarios (such as mobile phone screen projection, file sharing, mobile phone to VR glasses video transmission) and other scenarios. When the terminal device is applied to V2X, it can also be called a V2X device, for example, a smart car (or intelligent car), a digital car, an unmanned car (or driverless car or pilotless car or automobile), a self-driving car (or autonomous car), a pure electric vehicle (or battery EV), a hybrid electric vehicle (HEV), a range-extended EV (REEV), a plug-in hybrid electric vehicle (PHEV), a new energy vehicle (new energy vehicle), or a roadside unit (RSU). The terminal device can also be a device used in D2D communication, such as an electricity meter or water meter.

[0127] In addition, in the embodiments of the present application, the terminal device can also be a terminal device in an IoT system. IoT is an important part of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, thereby realizing an intelligent network of human-machine interconnection and object-to-object interconnection.

[0128] The various terminal devices described above, if located on a vehicle (e.g., placed in or installed in a vehicle), can be considered as vehicle-mounted terminal devices, which are also referred to as on-board units (OBUs). The terminal device of the present application can also be an on-board module, on-board module, on-board component, on-board chip, or on-board unit built into a vehicle as one or more components or units, and the vehicle can implement the method of the present application through the built-in on-board module, on-board module, on-board component, on-board chip, or on-board unit.

[0129] The terminal device may sometimes be referred to as UE, terminal, access station, UE station, remote station, wireless communication device, or user equipment, etc.

[0130] The first device involved in the embodiments of the present application later is, for example, a terminal device, or a functional module in a terminal device, such as a chip system; the second device is, for example, a terminal device, or a functional module in a terminal device, such as a chip system.

[0131] In the embodiment of the present application, the communication device for realizing the function of the terminal device can be a terminal device, or a device capable of supporting the terminal device to realize the function, such as a chip system, which can be installed in the terminal device. In the technical solution provided in the embodiment of the present application, the technical solution provided in the embodiment of the present application is described by taking the device for realizing the function of the terminal device as an example. In addition, for the convenience of description, the terminal device in the embodiment of the present application is described by taking the UE as an example, for example, the first device is referred to as the first UE, and the second device is referred to as the second UE.

[0132] The network devices in the embodiments of the present application include, for example, access network devices, and / or core network devices. The access network device is a device with wireless transceiver functions, which is used to communicate with the terminal device. The access network devices include but are not limited to base stations (base transceiver station (BTS), node B (Node B), evolved node B (eNodeB) / eNB, or the next generation node B (gNodeB) / gNB), transmission reception points (TRP), base stations subsequently evolved by the third generation partnership project (3GPP), access nodes in wireless fidelity (Wi-Fi) systems, wireless relay nodes, wireless backhaul nodes, etc. The base station can be: a macro base station, a micro base station, a pico base station, a small station, a relay station, etc. Multiple base stations can support networks with the same access technology, or they can support networks with different access technologies. The base station can include one or more co-station or non-co-station transmission and receiving points. The access network device may also be a wireless controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. The access network device may also be a server, etc. For example, the network device in the V2X technology may be a road side unit (RSU). The following describes the access network device using a base station as an example. The base station can communicate with the terminal device, or it can communicate with the terminal device through a relay station. The terminal device can communicate with multiple base stations in different access technologies. The core network device is used to implement functions such as mobility management, data processing, session management, policy and billing. The names of the devices that implement core network functions in systems with different access technologies may be different, and the embodiments of the present application are not limited to this. Taking the fifth generation mobile communication technology (5G) system as an example, the core network equipment includes: access and mobility management function (AMF), session management function (SMF), policy control function (PCF) or user plane function (UPF), etc.

[0133] In the CU-DU architecture, the access network equipment may include one or more logical network elements such as a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU may be configured separately or included in the same network element, such as a baseband unit (BBU). The RU may be included in a radio frequency device or radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0134] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called open CU (open-CU, O-CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, the embodiments of the present application are described by taking CU, CU-CP, CU-UP, DU and RU as examples. Any unit of CU (or CU-CP, CU-UP), DU and RU in the embodiments of the present application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0135] In the embodiments of the present application, the communication device for implementing the network device function may be a network device, or may be a device capable of supporting the network device to implement the function, such as a chip system, which may be installed in the network device. In the technical solutions provided in the embodiments of the present application, the technical solutions provided in the embodiments of the present application are described by taking the network device as an example of the device for implementing the network device function being a network device.

[0136] Please refer to Figure 1, which is a schematic diagram of the current transmission path of call data. In Figure 1, for example, a base station is deployed on a satellite, and both the calling UE and the called UE access the network through the base station on the same satellite. The calling UE initiates a call, and the call data reaches the satellite through the service link between the calling UE and the satellite, and then reaches the gateway through the feedback link between the satellite and the ground gateway. The gateway sends it to other network elements in the ground network, such as core network elements, IMS network elements, etc. After being processed by the network elements in the ground network, the call data reaches the gateway through the feedback link, is sent to the satellite via the gateway, and then is sent to the called UE by the satellite. It can be seen that the transmission path of the call data is long, and during the transmission process, it must be routed from the satellite to the ground network. The distance between network elements is long, which results in a large call delay.

[0137] Figure 1 illustrates only one satellite. In practice, multiple satellites may be connected to a terrestrial gateway via inter-satellite links. For example, a service link is established between the UE and satellite 1, a feedback link is established between satellite 2 and the terrestrial gateway, and an inter-satellite link is established between satellite 1 and satellite 2. In this scenario, the inter-satellite link and the feedback link can be combined to form a terrestrial link.

[0138] In view of this, the UPF in the embodiment of the present application can locally exchange call data between the first UE and the second UE based on the first configuration information. The first UE and the second UE both access the network via satellite. For example, the UPF can exchange call data between the first UE and the second UE on the satellite. As a result, call data can be exchanged on the satellite without having to be routed to the terrestrial network, shortening the transmission path of the call data and reducing latency. In addition, because the UPF can perform local exchange of call data between devices, the call data can directly reach the call end device from the UPF without having to be transmitted through certain IMS network elements in the IMS network, further shortening the transmission path and reducing latency.

[0139] The technical solutions provided in the embodiments of the present application can be applied to the fourth generation mobile communication technology (the 4th generation, 4G) system, such as the long term evolution (long term evolution, LTE) system, or can be applied to the fifth generation mobile communication technology (the 5th generation, 5G) system, such as the NR system, or can also be applied to the next generation mobile communication system or other similar communication systems, such as the sixth generation mobile communication technology (the 6th generation, 6G) system, etc., without specific limitation. In addition, the technical solutions provided in the embodiments of the present application can be applied to the side link (sidelink, SL). For example, the SL belongs to a D2D scenario, such as an NR-D2D scenario, etc., or belongs to a V2X scenario, such as an NR-V2X scenario, etc. For example, the embodiments of the present application can be used in the fields of factory manufacturing, whole-house intelligence, intelligent driving, assisted driving, intelligent connected vehicles, or indoor commercial scenarios.

[0140] Please refer to Figure 2A, which is a schematic diagram of a 5G network architecture, which is also a network architecture used in the embodiments of the present application. Figure 2A shows the interaction relationship between network functions and entities and the corresponding interfaces. For example, the UE and AMF can interact through the N1 interface, and the interaction message is called the N1 message. Some of the interfaces in Figure 2A can be implemented in the form of service-oriented interfaces. Figure 2A includes a network slice selection function (NSSF), a network exposure function (NEF), a network repository function (NRF), PCF, UDM, an application function (AF), an authentication server function (AUSF), AMF, SMF, a signaling control point (SCP), UE, (R)AN, UPF, a data network (DN), etc.

[0141] The UE, (R)AN, UPF, and data network (DN) in Figure 2A are generally referred to as data plane network functions and entities. User data traffic can be transmitted through the protocol data unit (PDU) session established between the UE and DN, and the transmission will pass through the (R)AN and UPF network function entities. The other parts in Figure 2A are called control plane network functions and entities, which are mainly responsible for functions such as authentication and authorization, registration management, session management, mobility management, and policy control, thereby achieving reliable and stable transmission of user-layer traffic. Among them, the user plane is used to carry service data, and the control plane is used to carry signaling messages.

[0142] Access network elements, such as (R)ANs, are primarily responsible for air interface functions such as radio resource management, quality of service management, data compression, and encryption. These access network devices can include various base stations, such as macro base stations, micro base stations, relay stations, and access points. In systems using different wireless access technologies, the names of devices with base station functionality may vary. For example, in 5G systems, they are referred to as gNBs.

[0143] AMF, the access and mobility management entity, is a core network element and is primarily responsible for signaling processing related to UE access and mobility management, such as access control, mobility management, registration and deregistration, and SMF selection. As the anchor point for N1 and N2 signaling connections, it provides routing for N1 and N2 messages between the UE and the core network elements, and is responsible for maintaining and managing the UE's status information. When the AMF provides services for a UE session, it provides control plane storage resources for the session to store the session identifier, the SMF network element identifier associated with the session identifier, and so on.

[0144] SMF, Session Management Entity, is responsible for the signaling processing part of session management, user plane network element selection, user plane network element redirection, Internet Protocol (IP) address allocation, bearer establishment, modification and release, and quality of service (QoS) control.

[0145] The UPF (User Plane Entity) is responsible for forwarding and receiving user data within the UE. It receives user data from the DN and transmits it to the UE via access network elements. The UPF also receives user data from the UE via access network elements and forwards it to the DN. The SMF manages and controls the transmission resources and scheduling functions within the UPF that serve the UE.

[0146] NEF mainly supports the secure interaction between the 3rd Generation Partnership Project (3GPP) network and third-party applications.

[0147] An AF is a server that provides certain services to users and is therefore also called an application server or service server. The AF can be deployed in the operator's network or a third-party AF.

[0148] DN, such as operator service IMS, Internet access or third-party services.

[0149] PCF is responsible for policy control decisions, providing policy rules for control plane functions, and flow-based charging control functions.

[0150] UDM is mainly responsible for UE subscription data management, including storage and management of UE identification, UE access authorization, etc.

[0151] NRF, supports registration and discovery of network functions.

[0152] The relevant interfaces between network element functions involved in the embodiments of this application include:

[0153] N1: Interface between UE and core network control plane.

[0154] N2: Communication interface between (R)AN and core network control plane.

[0155] N3: Communication interface between (R)AN and UPF, used to transmit user plane data.

[0156] N4: Communication interface between SMF and UPF, used by SMF to configure policies for UPF, etc.

[0157] N6: Communication port between UPF and DN.

[0158] Please refer to Figure 2B, which is a schematic diagram of the IMS architecture, which is also a network architecture used in the embodiments of the present application. The network elements mainly involved in the IMS architecture include UE, (R)AN, UPF, AMF, visit-SMF, UDM, home subscriber server (HSS), home-SMF, H-PCF, proxy-call session control function (Proxy-Call Session Control Function), service-call session control function (S-CSCF), telecom application server (TAS), interconnection border control function (IBCF), breakout gateway control function (BGCF), media gateway control function (MGCF), called party (B party), etc. Figure 2B shows two transmission paths: the bold solid line shows the control plane transmission path, and the dotted line shows the media plane transmission path. In addition, Sh, Cx, Rx, N5, Mw, ISC, N5, etc. in Figure 2B all represent interface names.

[0159] The P-CSCF is the first access point in the IMS. The P-CSCF acts like a proxy, accepting requests and servicing them internally or forwarding them upwards.

[0160] The S-CSCF performs session control for the UE and maintains session state to support services as required by the network operator.

[0161] Based on the architecture shown in Figures 2A and 2B, please refer to Figures 3A to 3E, which are several network architectures applied in the embodiments of the present application.

[0162] In Figure 3A, the access network elements are located on the satellite, or the satellite is considered to have the function of an access network element. In addition to the access network elements, other network elements used to transmit call services (such as core network elements and / or IMS network elements) are located on the ground. Among them, the IMS network elements in the embodiments of the present application can be network elements located within the IMS, such as the P-CSCF and S-CSCF, which can all be referred to as IMS network elements.

[0163] In Figure 3B , the UPF is located on the satellite, or the satellite is considered to have the functionality of the UPF. In addition to the UPF, other network elements used to transmit call services (e.g., access network elements, core network elements other than the UPF, or one or more of the IMS network elements) are located on the ground. Figure 3B uses the example of a calling UE and a called UE being served by the same access network element on the ground. It is understood that in a scenario where the UPF is located on the satellite and the access network equipment is on the ground, the calling UE and the called UE can be served by different access network elements.

[0164] In Figure 3C , the access network elements and UPF are located on the satellite, or the satellite is considered to have the functions of the access network elements and UPF. In addition to the access network elements and UPF, other network elements used to transmit call services (such as other core network elements and / or IMS network elements other than the UPF) are located on the ground.

[0165] In Figure 3D , the access network elements, UPF, and some or all of the network elements in the IMS (e.g., P-CSCF and / or S-CSCF) are all located on the satellite, or the satellite is considered to have the functions of the access network elements, UPF, and some or all of the network elements in the IMS (e.g., P-CSCF and / or S-CSCF). In addition, other network elements used to transmit call services (e.g., other core network elements other than the UPF and / or other network elements in the IMS) are all located on the ground.

[0166] In Figure 3E , the UPF and some or all network elements in the IMS (e.g., P-CSCF and / or S-CSCF, etc.) are all located on the satellite, or the satellite is considered to have the functions of the UPF and some or all network elements in the IMS (e.g., P-CSCF and / or S-CSCF, etc.). In addition, other network elements used to transmit call services (e.g., access network elements, other core network elements other than the UPF, or one or more other network elements in the IMS) are all located on the ground. In the scenario where the access network equipment is on the ground, the calling UE and the called UE can be served by the same or different access network elements.

[0167] Alternatively, all network elements used to transmit call services may be set up on the satellite, and this embodiment of the present application does not limit this.

[0168] According to the deployment scenarios of satellites and terrestrial networks, satellite network architectures can be divided into three categories: transparent satellite architecture, satellite backhaul architecture, and regenerative satellite architecture. The architecture in which the UE is connected to the terrestrial access network via satellite can be called a transparent satellite architecture (not included in Figures 3A to 3E). The architecture in which the UE is connected to the terrestrial access network and then connected to the terrestrial network via satellite can be called a satellite backhaul architecture (for example, Figure 3B or Figure 3E). In addition, the architecture in which the access network equipment is included on the satellite is called a regenerative satellite architecture (for example, Figures 3A, 3C, or 3D). The embodiments of this application involve satellite backhaul architecture and regenerative satellite architecture, but do not involve satellite backhaul architecture.

[0169] In addition, FIG. 3A to FIG. 3E take the example that the calling UE and the called UE access the network through the same satellite.

[0170] In order to better introduce the embodiments of the present application, the method provided by the embodiments of the present application is introduced below in conjunction with the accompanying drawings. In various embodiments of the present application, the call data includes, for example, voice data and / or video data and / or IMS data channel (data channel) data. In various embodiments of the present application, the UPF serving a UE may be the UPF of the IMS PDU session serving the UE, such as the anchor UPF of the IMS PDU session, or it may be the non-anchor UPF of the IMS PDU session, or it may be called an intermediate UPF (intermediate UPF). In various embodiments of the present application, deploying a network element on a satellite can also be described as the network element being located on the satellite. Unless otherwise specified hereinafter, the steps represented by dotted lines in the accompanying drawings corresponding to the various embodiments of the present application are all optional steps.

[0171] The methods provided in each embodiment of the present application can be applied to the network architecture shown in any one of Figures 3A to 3E. For example, the first UE involved in each embodiment of the present application can be the calling UE shown in any one of Figures 3A to 3E; the second UE involved in each embodiment of the present application can be the called UE shown in any one of Figures 3A to 3E; the IMS network element involved in each embodiment of the present application can be the P-CSCF shown in any one of Figures 3A to 3E, or the S-CSCF shown in any one of Figures 3A to 3E; the first core network network element involved in each embodiment of the present application can be the SMF shown in any one of Figures 3A to 3E. In the following introduction, the first core network network element is taken as an example of SMF. Among them, the scenario of "UPF deployed on a satellite" described later is, for example, the scenario shown in any one of Figures 3B, 3C, 3D or 3E; the scenario of "RAN deployed on a satellite" described later is, for example, the scenario shown in any one of Figures 3A, 3C or 3D.

[0172] An embodiment of the present application provides a communication method. Please refer to Figure 4A or Figure 4B for a flowchart of the method.

[0173] S401: A first UE establishes a PDU session. The PDU session can be used to carry IMS communication-related signaling and data, and is therefore also referred to as an IMS PDU session.

[0174] In S401, the first UE can send a PDU session establishment request message to the SMF through the AMF, and the data network name (DNN) included in the PDU session establishment request message is IMS, that is, the PDU session is used to carry signaling and data related to IMS communication. In the process of executing an emergency call, the DNN included in the PDU session establishment request message may also be a DNN describing emergency communication, such as emergency. After receiving the PDU session establishment request message, the SMF sends a PDU session establishment accept message to the UE, and the PDU session establishment accept message may include the IP address corresponding to the PDU session. The IP address is allocated to the first UE by the SMF or UPF during the establishment of the PDU session, and is used for the first UE to communicate subsequently through the PDU session. In addition, in S401, the SMF can establish a quality of service (QoS) flow for the first UE to carry IMS signaling, and the 5G QoS identifier (5QI) of the QoS flow is, for example, 5. More steps for establishing the PDU session are not described here.

[0175] During the PDU session establishment process, the first UE may also obtain the address of the P-CSCF in the IMS for subsequent communication between the first UE and the IMS.

[0176] S402: The first UE performs IMS registration.

[0177] In S402, the first UE may send a session initialization protocol (SIP) registration message to an IMS network element (e.g., P-CSCF) through the IMS PDU session and QoS flow established in S401 to perform an IMS registration process, or request registration to the IMS network element, or request registration to the IMS network element. Optionally, the SIP registration message may include a private (P)-access-network-information (Info) information element, which may indicate that the first UE accesses the network via a satellite. For example, the first UE may receive system information from the access network element, and may determine whether the first UE accesses the network via a satellite based on the system information. Alternatively, the first UE may also determine whether the first UE accesses the network via a satellite based on the public land mobile network (PLMN) where the first UE is located.

[0178] If the registration is successful, the first UE may receive a SIP registration ok (or 200 OK) message from the IMS network element (eg, P-CSCF). Detailed description of the IMS registration process is omitted. At step S402, the first UE is registered with the IMS.

[0179] Among them, for the first UE performing IMS registration, the IMS network element (for example, including a P-CSCF and / or an S-CSCF, etc.) may store the registration information of the first UE. The registration information of the first UE, for example, includes one or more of the following: a first identifier of the first UE, an IP address of the first UE, or a second identifier of the first UE. The first identifier of the first UE can be used to indicate (or identify) the first UE in the communication system, for example, to uniquely indicate the first UE in the communication system. The second identifier of the first UE can be used to indicate (or identify) the first UE in the communication system, for example, to uniquely indicate the first UE in the communication system. Optionally, the second identifier of the first UE, for example, includes a uniform resource locator (URL) of the first UE and / or includes a uniform resource identifier (URI) of the first UE. The URI of the UE (for example, the first UE or the second UE) described in each embodiment of the present application, for example, includes the telephone (TEL) URI of the UE; the URL of the UE (for example, the first UE or the second UE) described in each embodiment of the present application, for example, includes the SIP URL of the UE. In layman's terms, the TEL URI of a UE can be the telephone number of the UE, for example, the TEL URI of a UE is "Tel:+8613904710100". The SIP URL of a UE is similar to the address of a web mailbox, for example, "Sip:user1@ims.fj.chinamobile.com", where "user1" represents the user name. The first identifier of the first UE is, for example, the identity number (ID) of the first UE. The first identifier of the first UE and the IP address of the first UE can be carried in the SIP registration message sent by the first UE to the P-CSCF in S401. For example, the first identifier of the first UE can be carried in the contact field in the message header of the SIP registration message, or in the source field in the message header of the SIP registration message, or in the to field in the message header of the SIP registration message. The IP address of the first UE can be carried in the contact field in the message header of the SIP registration message, or in the via field in the message header of the SIP registration message.In addition, in addition to storing the second identifier of the first UE, the P-CSCF may also send the second identifier of the first UE to the first UE. For example, the second identifier of the first UE may be carried in the SIP registration ok message sent by the P-CSCF to the UE in S401. Optionally, the second identifier of the first UE may be carried in a private (P)-associated-URI in a message header of the SIP Registration ok message. The first identifier of the first UE is, for example, an IP multimedia private identity (IMPI) of the first UE, or includes some bits in the IMPI; or, the first identifier of the first UE is, for example, an IP multimedia public identity (IMPU) of the first UE, or includes some bits in the IMPU; or, the first identifier of the first UE is, for example, an international mobile subscriber identity (IMSI) of the first UE, or includes some bits in the IMSI; or, the first identifier of the first UE is, for example, a subscription permanent identifier (SUPI) of the first UE, or includes some bits in the SUPI; or, the first identifier of the first UE is, for example, a subscription concealed identifier (SUCI) of the first UE, or includes some bits in the SUCI. For example, the first identifier of the first UE is sip:460075205000317@ims.mnc007.mcc460.3gppnetwork.org, 460075205000317, where "460" is a mobile country code (MCC) identifier and "007" is a mobile network code (MNC) identifier.

[0180] S403: The second UE establishes a PDU session. Similarly, the PDU session may also be referred to as an IMS PDU session.

[0181] The process of establishing the PDU session by the second UE is similar to the process of establishing the PDU session by the first UE in S401, and reference may be made to the description of S401. During the PDU session establishment process, the second UE may also obtain the address of the P-CSCF in the IMS for subsequent communication between the second UE and the IMS.

[0182] S404: The second UE performs IMS registration.

[0183] For a second UE performing IMS registration, an IMS network element (e.g., a P-CSCF and / or an S-CSCF) may store the second UE's registration information. The second UE's registration information may include, for example, one or more of the following: a first identifier of the second UE, an IP address of the second UE, or a second identifier of the second UE. The first identifier of the second UE may be used to indicate (or identify) the second UE in the communication system, for example, to uniquely indicate the second UE in the communication system. The second identifier of the second UE may be used to indicate (or identify) the second UE in the communication system, for example, to uniquely indicate the second UE in the communication system. Optionally, the second identifier of the second UE may include, for example, a URL of the second UE and / or a URI of the second UE. The first identifier of the second UE may be, for example, an identity number (ID) of the second UE. The first identifier of the second UE and the IP address of the second UE may be carried in a SIP registration message sent by the UE to the P-CSCF in S403. For example, the first identifier of the second UE may be carried in the contact field of the SIP registration message header, in the from field of the SIP registration message header, or in the to field of the SIP registration message header. The IP address of the second UE may be carried in the contact field of the SIP registration message header, or in the via field of the SIP registration message header. In addition to storing the second identifier of the second UE, the P-CSCF may also send the second identifier to the second UE. For example, the second identifier of the second UE may be carried in the SIP registration ok message sent by the P-CSCF to the UE in S403. Alternatively, the second identifier of the second UE may be carried in the P-associated-URI in the header of the SIP registration ok message. The second identifier of the second UE may be, for example, the IMPI of the second UE or the IMPU of the second UE.

[0184] For more details about the registration process of the second UE, please refer to the registration process of the first UE described in S402.

[0185] Among them, the process of establishing an IMS PDU session between the first UE and the second UE and the IMS registration process are independent of each other, so S403 to S404 can occur before S401 to S402, or after S401 to S402, or can also occur simultaneously with S401 to S402. In addition, the first UE logically has a core network element and an IMS network element serving the first UE, and the second UE logically has a core network element and an IMS network element serving the second UE. Therefore, on the one hand, the SMF serving the IMS PDU session of the first UE and the SMF serving the IMS PDU session of the second UE can be the same or different, and the UPF serving the IMS PDU session of the first UE and the UPF serving the IMS PDU session of the second UE can be the same or different; or, the SMF and UPF serving the IMS PDU session of the first UE and the SMF and UPF serving the IMS PDU session of the second UE can be partially the same and partially different, for example, the SMF is the same but the UPF is different. On the other hand, the IMS network element serving the first UE and the IMS network element serving the second UE may be the same (for example, the same P-CSCF, the same S-CSCF), or different (for example, different P-CSCFs, different S-CSCFs), or partially the same or partially different (for example, the same P-CSCF, different S-CSCFs; or different P-CSCFs, the same S-CSCF). The embodiment of the present application takes the same serving PLMN for the first UE and the second UE as an example, and the IMS PDU sessions corresponding to the first UE and the second UE have the same or partially the same core network elements (for example, the same SMF, the same or different UPFs), and the IMS corresponding to the first UE and the second UE registered have the same or partially the same IMS network elements (for example, the same P-CSCF, the same or different S-CSCFs; or different P-CSCFs, the same or different S-CSCFs).

[0186] Optionally, based on whether the UPF serving the first UE and the second UE are the same or different, the UPF in the embodiment shown in Figure 4A or 4B of the embodiment of the present application may be the same UPF or include two different UPFs; similarly, based on whether the IMS network elements serving the first UE and the second UE are the same or different, the IMS network elements in the embodiment shown in Figure 4A or 4B can be understood as a set of IMS network elements or two sets of IMS network elements, wherein a set of IMS network elements can be understood as including at least one P-CSCF, or at least one P-CSCF and one S-CSCF.

[0187] The above steps S401 to S404 may be optional steps. For example, if the UE can make calls without performing IMS registration, the above steps S402 and S404 may not be performed.

[0188] The above is the registration process of two UEs. The following describes the call process between UEs.

[0189] S405. The first UE sends a first request to the IMS network element. Correspondingly, the IMS network element receives the first request from the first UE. The IMS network element is, for example, a P-CSCF or an S-CSCF. If the IMS network element is an S-CSCF, the P-CSCF may receive the first request from the first UE, and then the P-CSCF may send the first request to the S-CSCF after the P-CSCF processes the request in a certain manner (for example, adding, deleting, or modifying part or all of the information in the message header). It should be noted that the SIP message transmitted between two UEs may be processed in a certain manner by each IMS network element before being sent to the next network element when it passes through the IMS network element. For example, the first request message is transmitted from the first UE to the second UE, and needs to pass through the P-CSCF and S-CSCF of the first UE to the S-CSCF and P-CSCF of the second UE, and finally be sent to the second UE by the P-CSCF of the second UE. Therefore, the first request may be processed by the P-CSCF, S-CSCF of the first UE, and the S-CSCF and P-CSCF of the second UE (for example, adding, deleting or modifying part or all of the information in the message header). This description applies to all subsequent SIP messages in the embodiment.

[0190] The first request may be used to request a call with the second device, i.e., the first UE initiates a call process with the second UE by sending the first request. The first request may be, for example, a SIP invite message, or may be another message used to request a call. The first request may include, for example, the second identifier of the first UE and / or the second identifier of the second UE. For example, if the first request is a SIP invite message, the second identifier of the first UE may be included in the from field of the message header of the SIP invite message; the second identifier of the second UE may be included in the to field of the message header of the SIP invite message, or the second identifier of the second UE may be included in the request-URI of the message header of the SIP invite message. The SIP invite message may include a Session Description Protocol (SDP) request, which is used to negotiate a media type and a media format (or encoding method, codec method) with the called party, such as the media type requested by the caller and the media formats supported by the caller.

[0191] Optionally, the IMS network element may also receive second information, which may indicate that the first UE requests that the first UE's call data be exchanged over a satellite, and / or indicate that the second UE requests that the second UE's call data be exchanged over a satellite. For example, the second information includes information A and / or information B. Information A comes from the first UE and may indicate that the first UE requests that the first UE's call data be exchanged over a satellite; information B comes from the second UE and may indicate that the second UE requests that the second UE's call data be exchanged over a satellite. For example, information A may be included in a SIP message, such as the SIP registration message in S402, or the first request in S405, or another SIP message sent by the first UE to the IMS network element. For example, information B may be included in a SIP message, such as the SIP registration message in S404, or another SIP message sent by the second UE to the IMS network element. Optionally, if the IMS network element receives the second information, the IMS network element may determine whether the first UE and the second UE exchange call data on the satellite based on the second information; or the IMS network element may determine whether the first UE and the second UE exchange call data on the satellite due to receiving the second information, which is equivalent to the second information being the trigger condition for the determination process; or the IMS network element may also send the second information to the first core network network element (for example, the second information may be included in the first information to be introduced below), then the first core network network element may use the second information as a reference when determining whether the first UE and the second UE exchange call data on the satellite, or the first core network element may also determine whether the first UE and the second UE exchange call data on the satellite due to receiving the second information, which is equivalent to the second information being the trigger condition for the determination process.

[0192] Optionally, if the IMS network element receives the second information, the IMS network element may further send response information to the UE in response to the second information, for example, response information 1. Response information 1 may indicate that the UE's call data can be configured for exchange over a satellite. For example, if the second information includes information A, response information 1 may include response information a. Response information a may indicate that the first UE's call data can be configured for exchange over a satellite. For another example, if the second information includes information B, response information 1 may include response information b. Response information b may indicate that the second UE's call data can be configured for exchange over a satellite.

[0193] S406: The IMS network element sends the first information to the first core network element. Correspondingly, the first core network element receives the first information from the IMS network element.

[0194] The IMS network element may be, for example, a P-CSCF, an S-CSCF, or another network element within the IMS. If the IMS network element is an S-CSCF, the S-CSCF may first send the first information to the P-CSCF. For example, the S-CSCF may send a SIP 183 message to the P-CSCF. The SIP 183 message may include the first information. After receiving the SIP 183 message, the P-CSCF may send the first information to the first core network element.

[0195] The first core network element is, for example, an SMF, or a PCF, or may be another core network element. If the first core network element is an SMF, then optionally, the IMS element may send the first information to the PCF. The PCF may generate a policy control and charging (PCC) rule based on the first information, and then send the PCC rule to the SMF. For example, the PCC rule may include the first information, and thus the SMF is equivalent to obtaining the first information. FIG. 4A or FIG. 4B takes the example of the first core network element being an SMF.

[0196] For example, if the IMS network element determines that the first UE and / or the second UE access the network via satellite, S406 may be executed. Otherwise, the IMS network element may not execute S406 and instead follow the traditional call flow. For example, the IMS network element may determine whether the first UE accesses the network via satellite based on a SIP registration message from the first UE, for example, based on an indication in the P-Access-Network-Info information element in the SIP registration message. For another example, the IMS network element may determine whether the second UE accesses the network via satellite based on a SIP registration message from the second UE, for example, based on an indication in the P-Access-Network-Info information element in the SIP registration message. Alternatively, if the IMS network element is dedicated to satellite access, and if the IMS network element stores registration information for a UE, or a UE is registered with the IMS network element, or the UE is registered with the IMS where the IMS network element resides, the IMS network element may determine that the UE accesses the network via satellite. In the embodiment of the present application, the first UE and / or the second UE is taken as an example as a UE that accesses a network via a satellite.

[0197] The first information may also be called auxiliary information, or may have other names. The first information may instruct the first UE and the second UE to perform a call, or to perform IMS communication. The function of the first information is mainly to indicate that the communicating parties are between the first UE and the second UE, or to indicate that the communicating parties are the first UE and the second UE. For example, after the IMS network element receives the first request, it may send the first information to the first core network network element. The first information may inform the first core network network element that the first UE and the second UE are to perform a call. The first core network network element may then determine the two UEs of the call, for example, it may determine that the first UE is the calling UE and the second UE is the called UE, thereby configuring the call data between the first UE and the second UE to be exchanged on the satellite (for example, configuring the call data to be exchanged locally on the UPF on board).

[0198] Optionally, the first information may further instruct the first UE and the second UE to exchange call data on the satellite, or instruct the first UE and the second UE to perform local switching on the satellite, or instruct the first UE and the second UE to exchange call data on the satellite. The following uses the example of the first information instructing the first UE and the second UE to exchange call data on the satellite. This is equivalent to the decision of whether the first UE and the second UE exchange call data on the satellite being made by the IMS network element. The first core network network element may determine, based on the first information, that the first UE and the second UE exchange call data on the satellite, thereby configuring the call data between the first UE and the second UE to be exchanged on the satellite.

[0199] For example, before S406, the IMS network element may determine whether the first UE and the second UE can exchange call data over the satellite, or whether the first UE and the second UE meet conditions for exchanging call data over the satellite. If the first UE and the second UE can exchange call data over the satellite, or if it is determined that the first UE and the second UE meet the conditions for exchanging call data over the satellite, the first information may instruct the first UE and the second UE to initiate a call, and instruct the first UE and the second UE to exchange call data over the satellite. For example, the first information includes indication information A and indication information B, where indication information A instructs the first UE and the second UE to initiate a call, and indication information B instructs the first UE and the second UE to exchange call data over the satellite. If the first UE and the second UE cannot exchange call data over the satellite, or if it is determined that the first UE and the second UE do not meet the conditions for exchanging call data over the satellite, S406 may not be performed. Alternatively, although S406 is performed, the first information may instruct the first UE and the second UE to initiate a call, but not to exchange call data over the satellite. For example, the first information includes indication information A, and indication information A instructs the first UE and the second UE to initiate a call. In this implementation manner, the first core network element can determine, based on the first information, that the first UE and the second UE are exchanging call data on the satellite.

[0200] Optionally, the IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may include one or more of the following, or the IMS network element may determine that the first UE and the second UE exchange call data on the satellite through one or more of the following: determining that the network allows the call data of the first UE and / or the second UE to be exchanged on the satellite; or, determining that the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, determining that the first UE and the second UE are served by the same IMS network element; or, determining that the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, determining that the media description information supported by the first UE and the second UE matches; or, determining that the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN.

[0201] Alternatively, if the IMS network element determines that the first UE and the second UE meet the conditions for exchanging call data on the satellite, the conditions may include one or more of the following: the network allows the call data of the first UE and / or the second UE to be exchanged on the satellite; or, the first UE and the second UE are served by the same UPF, which is deployed on the satellite; or, the first UE and the second UE are served by the same IMS network element; or, the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, the media description information used by the first UE and the second UE matches; or, the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN.

[0202] Among them, whether the network allows the call data of a UE to be exchanged on the satellite can be determined based on the contract information of the UE. For example, for the first UE, the HSS can store the contract information of the first UE, and the contract information can indicate whether the network allows the call data of the first UE to be exchanged on the satellite. Then the IMS network element can determine whether the network allows the call data of the first UE to be exchanged on the satellite based on the contract information of the first UE. For the second UE, the processing method of the IMS network element is similar. For example, if the network does not allow the call data of the first UE and / or the second UE to be exchanged on the satellite, the IMS network element does not need to determine whether the first UE and the second UE exchange call data on the satellite. Optionally, if the IMS network element is an S-CSCF, the S-CSCF can request the contract information of the first UE and / or the second UE from the HSS. For example, the S-CSCF sends a third request to the HSS, such as a Cx-Put message or a Cx-Pull message. The Cx-Put message or Cx-Pull message may request the subscription information of the first UE and / or the second UE, or may be used to inquire of the HSS whether the network allows the exchange of call data of the first UE and / or the second UE over the satellite. The HSS sends third information to the S-CSCF, such as included in a Cx-Put response message or a Cx-Pull response message. The third information may indicate the subscription information of the first UE and / or the second UE, or may indicate whether the network allows the exchange of call data of the first UE and / or the second UE over the satellite. The S-CSCF may determine whether the first UE and the second UE exchange call data over the satellite based on the subscription information of the first UE and / or the second UE, or determine whether the first UE and the second UE exchange call data over the satellite based on whether the network allows the exchange of call data of the first UE and / or the second UE over the satellite.

[0203] Alternatively, if the IMS network element is a P-CSCF, the S-CSCF may first request the HSS for the subscription information of the first UE and / or the second UE, or inquire from the HSS whether the network allows the exchange of call data of the first UE and / or the second UE over the satellite. The S-CSCF then sends third information to the P-CSCF, for example, the third information included in a 200 OK message. The third information may indicate the subscription information of the first UE and / or the second UE, or indicate whether the network allows the exchange of call data of the first UE and / or the second UE over the satellite, or indicate whether data of the first UE and the second UE is exchanged over the satellite. For example, the S-CSCF may forward the information from the HSS to the P-CSCF. That is, the third information in this case may be information from the HSS, and the P-CSCF may further determine whether the first UE and the second UE are to exchange call data over the satellite based on the third information. Alternatively, after receiving the information from the HSS, the S-CSCF can determine whether the first UE and the second UE exchange call data on the satellite. The S-CSCF can indicate the S-CSCF's determination result to the P-CSCF through third information. The determination result is, for example, that the first UE and the second UE exchange call data on the satellite, or that the first UE and the second UE do not exchange call data on the satellite.

[0204] If the first UE and the second UE are served by the same UPF, the call data of the first UE and the second UE can be exchanged through the UPF. If the UPF is deployed on a satellite, the call data of the first UE and the second UE can be exchanged on the satellite. Optionally, the IMS network element may determine whether the first UE and the second UE are served by the same UPF by: determining whether the first UE and the second UE are served by the same IMS network element (the same IMS network element may be the IMS network element that performs the judgment process). If the first UE and the second UE are served by the same IMS network element, the IMS network element may determine that the first UE and the second UE are served by the same UPF. Alternatively, if the first UE and the second UE are served by different IMS network elements, the IMS network element may determine that the first UE and the second UE are served by different UPFs. For example, the IMS network element uniquely corresponds to one UPF. If both the first UE and the second UE are served by the IMS network element, it means that both the first UE and the second UE are served by the UPF corresponding to the IMS network element.

[0205] Optionally, the IMS network element may determine whether the first UE and the second UE are served by the same IMS network element in the following manner: based on the second identifier of the first UE and the second identifier of the second UE, it may determine whether the first UE and the second UE are served by the same IMS network element. For example, the registration information of the first UE may include the second identifier of the first UE, so the IMS network element may determine whether the IMS network element has stored the registration information of the first UE, or inquire whether the first UE is registered with the IMS network element based on the second identifier of the first UE; and the registration information of the second UE may include the second identifier of the second UE, so the IMS network element may inquire whether the IMS network element has stored the registration information of the second UE, or inquire whether the second UE is registered with the IMS network element based on the second identifier of the second UE. If the IMS network element stores the registration information of the first UE and the registration information of the second UE, or if both the first UE and the second UE are registered with the IMS network element, then the IMS network element may determine that the first UE and the second UE are served by the same IMS network element.

[0206] Alternatively, the IMS network element may determine whether the first UE and the second UE are served by the same UPF by adopting the following method: determine whether the request of the first UE and the request of the second UE come from the same UPF. If the request of the first UE and the request of the second UE come from the same UPF, it can be determined that the first UE and the second UE are served by the same UPF; otherwise, it can be determined that the first UE and the second UE are served by different UPFs. For example, to determine whether the request of the first UE and the request of the second UE come from the same UPF, the following method may be adopted: determine whether the source address information carried by the data packet corresponding to the request of the first UE and the source address information carried by the data packet corresponding to the request of the second UE are the same address information. The request of the first UE may include, for example, a first request, or include a SIP registration message sent by the first UE to the IMS network element in S402. The first request may be, for example, a SIP invite message. The SIP invite message or the SIP registration message may be implemented in the form of a data packet. The data packet may carry source address information, for example, the packet header of the data packet carries the source address information. Since the data packet is forwarded to the IMS network element by the UPF serving the first UE, the source address information carried in the packet header of the data packet may correspond to the public network address obtained by the UPF after translating the first UE's private network address. Furthermore, the IMS network element may also receive a request from a second UE, such as a SIP registration message sent by the second UE to the IMS network element in S402. Similarly, the SIP registration message may be implemented via a data packet, and the source address information carried in the packet header of the data packet may correspond to the public network address obtained by the UPF serving the second UE after translating the second UE's private network address. For the same UPF, translating the private network addresses of different UEs may result in the same public network address. Therefore, if the source address information carried in the data packet corresponding to the first UE's request and the data packet corresponding to the second UE's request are the same, the IMS network element can determine that the first and second UEs are served by the same UPF. In this case, there does not have to be a one-to-one correspondence between IMS network elements and UPFs. For example, a single IMS network element may correspond to one or more UPFs. In addition, optionally, if the IMS network element is a P-CSCF, this method of determining whether the first UE and the second UE are served by the same UPF can be used; if the IMS network element is an S-CSCF, since the request from the UE received by the S-CSCF is forwarded through the P-CSCF, the source address information carried by the data packet corresponding to the request may have become the address information of the P-CSCF, and the S-CSCF may not be able to determine whether the first UE and the second UE are served by the same UPF based on the source address information carried by the data packet.For example, for the S-CSCF, the method of determining whether the first UE and the second UE are served by the same IMS network element as described above may be used to determine whether the first UE and the second UE are served by the same UPF.

[0207] If the first UE and the second UE are served by the same IMS network element, for example, the IMS network element uniquely corresponds to one UPF, it can also indicate that the first UE and the second UE are served by the same UPF, so that the IMS network element can determine that the first UE and the second UE exchange call data on the satellite.

[0208] If the first UE and the second UE are served by different UPFs, and both UPFs are deployed on a satellite, the IMS network element may also determine that the first UE and the second UE are exchanging call data on the satellite. In this case, the IMS network element may not be able to determine whether the different UPFs can communicate with each other or whether a channel for data transmission can be established. However, the IMS network element may assume that a channel for data transmission can be established between the different UPFs.

[0209] During a traditional call, when call data passes through the IMS, the IMS network element may process the call data, for example, by performing format conversion. For example, if the media description information of the UEs on both sides of the call may not match, the processing of the IMS network element can enable the call peer to identify the received call data. In the embodiment of the present application, the call data between the first UE and the second UE can directly reach the call peer (the first UE or the second UE) without passing through the IMS. Therefore, the media description information supported by the first UE and the second UE can optionally match, so that the first UE and the second UE can identify the call data from the call peer without having to go through the IMS network element.

[0210] Whether the media description information supported by the first UE and the second UE matches is determined, for example, based on the received session description protocol (SDP) of the first UE and the second UE. The media description information may indicate one or more of the following information: media type (e.g., video, audio, etc.), transport protocol (e.g., real-time transport protocol (RTP), user datagram protocol (UDP), or IP, etc.), or media format (e.g., G711, G721, advanced audio coding (AAC)-low delay (LD), H.264 video, moving picture expert group (MPEG) video). The matching of the media description information of the two UEs can be understood as that the receiving UE of the two UEs can decode the data from the sending UE of the two UEs without the need for transcoding processing by other network elements. For example, if the media description information of the first UE and the second UE matches, then the first UE and the second UE support the same or common media format. After SDP negotiation, the first UE and the second UE can use the same media format. Then, for the call data from the first UE, the second UE can decode it without the need for transcoding processing by other network elements; similarly, for the data from the second UE, the first UE can also decode it, also without the need for transcoding processing by other network elements.

[0211] The serving PLMN of a UE can be understood as the network that the UE is currently accessing. If the serving PLMN of two UEs is the same, it can be understood that the two UEs are currently accessing the same network, which may include any one or more of the following situations:

[0212] (1) Neither UE is roaming. The serving PLMNs of both UEs are home PLMNs (HPLMNs), and the two HPLMNs are the same PLMN.

[0213] (2) At least one UE is roaming. If one UE is roaming and the other is not roaming, the serving PLMN of the roaming UE is the visit PLMN (VPLMN) of the roaming UE; the serving PLMN of the non-roaming UE is the HPLMN of the non-roaming UE, and the VPLMN of the roaming UE is the same as the HPLMN of the non-roaming UE. Alternatively, if both UEs are roaming, the VPLMN of the two UEs is the same, but the HPLMN of the two UEs may be the same or different.

[0214] In case 1, that is, when neither of the two UEs roams, the P-CSCFs of the two UEs are both P-CSCFs of the HPLMN. The two P-CSCFs may be the same P-CSCF or different P-CSCFs.

[0215] In scenario 2, when at least one UE is roaming, the P-CSCF serving the roaming UE may be the P-CSCF of the VPLMN of the roaming UE or the P-CSCF of the HPLMN of the roaming UE. Therefore, when the P-CSCF of the roaming UE is the P-CSCF of the VPLMN of the roaming UE, the P-CSCFs of the two UEs may be the same or different. When the P-CSCF of the roaming UE is the P-CSCF of the HPLMN of the roaming UE, if both UEs are roaming UEs and their HPLMNs are different, the P-CSCFs of the two UEs may be different. If both UEs are roaming UEs and their HPLMNs are the same, the P-CSCFs of the two UEs may be the same or different.

[0216] If two UEs have the same serving PLMN, this may indirectly indicate, in some network deployment scenarios, that the two UEs are served by the same IMS network element or the same UPF. In addition to these methods, the IMS network element may also use other methods to determine whether the first UE and the second UE can exchange call data over the satellite, and this is not limited to these methods.

[0217] Alternatively, whether the first UE and the second UE exchange call data on the satellite may be decided by the first core network element, rather than by the IMS network element. In this case, the first information may instruct the first UE and the second UE to perform a call, rather than instructing the first UE and the second UE to exchange call data on the satellite. For example, the first information includes indication information A, and indication information A instructs the first UE and the second UE to perform a call. After receiving the first information, the first core network element may determine whether the first UE and the second UE exchange call data on the satellite, or determine whether the first UE and the second UE meet the conditions for exchanging call data on the satellite. After receiving the first information, the first core network element may determine whether the first UE and the second UE exchange call data on the satellite. If it is determined that the first UE and the second UE exchange call data on the satellite, the call data between the first UE and the second UE may be configured to be exchanged on the satellite.

[0218] Optionally, the first core network element determining that the first UE and the second UE exchange call data over a satellite may include one or more of the following, or the first core network element may determine that the first UE and the second UE exchange call data over a satellite by one or more of the following: the first core network element determining whether the first UE and the second UE exchange call data over a satellite based on a UPF serving the first UE and the second UE, or the first core network element determining whether the first UE and the second UE exchange call data over a satellite based on a RAN serving the first UE and the second UE. For example, the first core network element determining that the first UE and the second UE exchange call data over a satellite based on the UPF serving the first UE and the second UE may be implemented as follows: the first core network element determining that the first UE and the second UE are served by the same UPF. If the first UE and the second UE are served by the same UPF, then it may be determined that the first UE and the second UE exchange call data over a satellite, and the UPF may be used to implement the exchange of call data. For another example, the first core network element determines, based on the UPFs serving the first UE and the second UE, that the first UE and the second UE exchange call data over a satellite. This can also be achieved by: the first core network element determines that the first UE and the second UE are served by different UPFs, and that data transmission channels can be established (or are capable of being established; or have been established) between the different UPFs. If the first UE is served by different UPFs, but the two UPFs support establishing a data transmission channel, then it can also be determined that the first UE and the second UE exchange call data over a satellite, and the two UPFs can be used to implement the exchange of call data.

[0219] The first core network element determines, based on the RANs serving the first UE and the second UE, whether the first UE and the second UE are exchanging call data over the satellite. This can be accomplished by: the first core network element determines that the first UE and the second UE are served by the same RAN (or the same access network element). If the first UE and the second UE are served by the same RAN, it can be determined that the first UE and the second UE are exchanging call data over the satellite, and the RAN can be used to implement the exchange of call data.

[0220] In summary, the first core network element needs to determine that the first UE and the second UE exchange call data on the satellite, which may include one or more of the following: determining that the first UE and the second UE are served by the same UPF; or, determining that the first UE and the second UE are served by the same RAN (or, the same access network element); or, determining that the first UE and the second UE are served by different UPFs, and that the different UPFs support the establishment (or, can establish; or, have established) of data transmission channels.

[0221] Alternatively, if the first core network element determines that the first UE and the second UE meet the conditions for exchanging call data on the satellite, the conditions may include one or more of the following: the first UE and the second UE are served by the same UPF; the first UE and the second UE are served by the same RAN (or, the same access network element); or, the first UE and the second UE are served by different UPFs, and the different UPFs support the establishment (or, are capable of establishing; or, have established) of data transmission channels.

[0222] If the first UE and the second UE are served by the same UPF, call data between the first UE and the second UE can be exchanged via the UPF. Optionally, the UPF can be deployed on a satellite, in which case call data between the first UE and the second UE can be exchanged on the satellite. For example, if the first core network element is an SMF, the SMF selects the UPF serving the UE. Therefore, the SMF knows the UPFs serving the first UE and the second UE and can determine whether the two UEs are served by the same UPF.

[0223] If the first UE and the second UE are served by the same RAN, call data between the first UE and the second UE can be exchanged via the RAN. Alternatively, the RAN can be deployed on a satellite, allowing call data between the first UE and the second UE to be exchanged on the satellite. In other words, in this embodiment of the present application, local switching between the first UE and the second UE on the satellite is not limited to being achieved through the UPF; it can also be achieved through other network elements, such as the RAN. The RAN serving the UE is also known to the first core network element, so the first core network element can determine whether the first UE and the second UE are served by the same RAN.

[0224] If the first UE and the second UE are served by different UPFs and the different UPFs can communicate or establish a data transmission channel, this indicates that the call data of the first UE and the second UE can be exchanged locally through the UPFs. Optionally, if the different UPFs are both deployed on a satellite, the call data of the first UE and the second UE can be exchanged on the satellite.

[0225] In addition, the first core network element may use other methods to determine whether the first UE and the second UE can exchange call data on the satellite, and there is no restriction on this.

[0226] Since the IMS network elements serving the first UE and the second UE may be the same or different (for example, as mentioned above, the IMS network element serving the first UE and the IMS network element serving the second UE may be the same set of IMS network elements, or two different sets of IMS network elements), when the IMS network elements are different, if the IMS network element decides whether to exchange call data on the satellite, the decision-making process may involve interaction between the two sets of IMS network elements; or, if the first core network element decides whether to exchange call data on the satellite, the two P-CSCFs serving the two UEs may respectively send the first information to the first core network element, and there may be no interaction between the two sets of IMS network elements.

[0227] Alternatively, either the IMS network element or the first core network element need not determine whether the first UE and the second UE can exchange call data over the satellite, but can instead directly configure the first UE and the second UE to exchange call data over the satellite. For example, the IMS network element may instruct the first UE and the second UE to exchange call data over the satellite through a first message without determining the connection. Alternatively, the IMS network element may not instruct the first UE and the second UE to initiate a call through a first message, and upon receiving the first message, the first core network element may execute S407 described below without determining the connection. This is equivalent to the first core network element configuring the first UE and the second UE to exchange call data over the satellite without determining the connection. If the determination is not performed, the failure rate of the first UE and the second UE exchanging call data over the satellite may increase because the first UE and the second UE may not actually meet the conditions for exchanging call data over the satellite. However, not performing a determination can save time and improve the efficiency of UE call execution. This embodiment of the present application primarily uses the example of performing a determination.

[0228] Optionally, the first information may further include (or indicate) one or more of the following: a first identifier of the first UE, a second identifier of the first UE, address information of the first UE, a first identifier of the second UE, a second identifier of the second UE, address information of the second UE, caller information, called party information, or descriptive information of call data between the first UE and the second UE. At least one of the first identifier of the first UE, the second identifier of the first UE, or the address information of the first UE may be used to indicate the first UE; and at least one of the first identifier of the second UE, the second identifier of the second UE, or the address information of the second UE may be used to indicate the second UE. The parameters used to indicate the first UE are not limited to one or more of the first identifier, the second identifier, or address information, and may also include other parameters, as long as the first core network device can uniquely identify the first UE based on the parameters. The same applies to the second UE. The caller information and / or called party information may be used to indicate which of the first UE and the second UE is the calling UE and which is the called party, for example, the first UE is the calling UE and the second UE is the called party. The description information may indicate call data to be exchanged over the satellite, for example, the description information includes a service data flow (SDF) template. The SDF template may include an IP triplet (source / destination address, source port number, protocol type) or an IP quintuple (destination address, destination port number, source address, source port number, protocol type). For example, for the call data of the first UE, the description information of the call data may include {source address = calling address / destination address = called address, source port number = calling port number / destination port number = called port number, protocol type = UDP} or IP quintuple {destination address = called address, destination port number = called port number, source address = calling address, source port number = calling port number, protocol type = UDP}; for the call data of the second UE, the description information of the call data may include {source address = called address / destination address = calling address, source port number = called port number / destination port number = calling port number, protocol type = UDP} or IP quintuple {destination address = calling address, destination port number = calling port number, source address = called address, source port number = called port number, protocol type = UDP}. Among them, the address information of the first UE may include the address information of the first UE in an IP triplet or an IP quintuple. The IMS network element can obtain the address information of the first UE through a request message sent by the first UE to the IMS network element, for example, by obtaining it from a SIP message sent by the first UE to the IMS network element (for example, obtaining it from a message body such as a SIP registration message or a SIP invite message).In addition, the SIP message of the first UE can be sent to the IMS network element in the form of a data packet (e.g., an IP data packet). The IMS network element can also obtain the address information of the first UE through the source address information carried in the packet header of the data packet (the packet header of the IP data packet carrying the SIP message. Alternatively, because the SIP message is implemented in the form of a data packet, the packet header of the data packet can also be understood as the message header of the SIP message). There are two ways to obtain the address information of the first UE based on the IMS. The address information of the first UE, for example, indicates the address of the first UE in the private network, such as the IP address allocated to the first UE by the SMF or UPF during the process of establishing the IMS PDU session. The first UE can carry the private network address when sending a SIP message to the IMS network element; or, the address information of the first UE can also indicate the address of the first UE in the public network, for example, the UPF serving the first UE can allocate an address in the public network to the first UE. For example, when the first UE sends a SIP message to the IMS network element, the IP address in the header of the data packet carrying the SIP message (the private network address of the first UE in this case) is subjected to network address translation (NAT) by the UPF when passing through the UPF, and the address in the public network is obtained after conversion; or, the address information of the first UE can also indicate an address determined based on the private network address and public network address of the first UE, such as a combination of the private network address and public network address of the first UE. Accordingly, the address information of the first UE in the first information may include the IP address in the message body of the SIP message received by the IMS network element from the first UE, and / or include the source address in the header of the data packet received by the IMS network element and carrying the SIP message of the first UE. For the specific process of the IMS network element obtaining the address information of the first UE, please refer to the description in S507 and will not be described in detail here. The implementation method of the address information of the second UE in the first information is similar and will not be described in detail here.

[0229] For example, the first information may include one or more of indication information C, indication information D, or indication information E, where indication information A indicates the first identifier of the first UE, indication information D indicates the first identifier of the second UE, and indication information E indicates the description information. The one or more items included in the first information may be used to assist the first core network element in determining whether the first and second UEs can exchange call data over the satellite. For example, if an IMS network element determines whether the first and second UEs can exchange call data over the satellite, for example, if the first information instructs the first and second UEs to exchange call data over the satellite, then the first information may not necessarily include the above items. For example, the first information may simply instruct the first and second UEs to initiate a call, enabling the SMF to determine the devices at both ends of the call. For another example, if the first core network element determines whether the first and second UEs can exchange call data over the satellite, then the first information may include the above items to assist the first core network element in making the decision. Alternatively, even if an IMS network element determines whether the first and second UEs can exchange call data over the satellite, the first information may also include the above items, without limitation.

[0230] Because the first UE and the second UE are respectively the calling and the called, for example, the P-CSCF of the first UE may generate the first message based on the first UE being the calling UE, while the P-CSCF of the second UE may generate the first message based on the second UE being the called UE. Therefore, the content of the first message sent by the P-CSCF of the first UE to the first core network element and the first message sent by the P-CSCF of the second UE to the first core network element may be different.

[0231] Optionally, if the first core network element determines whether the first UE and the second UE can exchange call data over the satellite, the first information may further indicate that the first UE and the second UE meet conditions for exchanging call data over the satellite. For example, the IMS element determines that the first UE and the second UE can exchange data over the satellite, or determines that the first UE and the second UE meet conditions for exchanging call data over the satellite, but the IMS element may not make a decision. Instead, the IMS element may send the first information to the first core network element, which then determines whether the first UE and the second UE can exchange call data over the satellite. In this case, the first information indicates that the first UE and the second UE meet the conditions for exchanging call data over the satellite, indicating that the IMS element determines that the first UE and the second UE can exchange call data over the satellite. Whether the first UE and the second UE can exchange call data over the satellite may be determined by the SMF, for example, the first core network element may make the decision in the aforementioned manner, wherein the first core network element may use the first information as a reference when making the decision. For example, if the first information indicates that the first UE and the second UE meet the conditions for exchanging call data over a satellite, the first core network element may directly determine that the first UE and the second UE exchange call data over a satellite. Alternatively, the first core network element may determine whether the first UE and the second UE are served by the same UPF. If so, the first core network element may determine that the first UE and the second UE exchange call data over a satellite. If they are served by different UPFs but the different UPFs can communicate with each other, the first core network element may also determine that the first UE and the second UE exchange call data over a satellite. Alternatively, if they are served by different UPFs but the different UPFs cannot communicate with each other, the first core network element may determine that the first UE and the second UE cannot exchange call data over a satellite. Alternatively, the first core network element may determine that the first UE and the second UE exchange call data over a satellite via a RAN. Optionally, the first UE and the second UE may be served by the same RAN or different RANs, and the RAN serving the first UE and the second UE may be deployed over a satellite.

[0232] Among them, the first information can be a complete information, and the first information can indicate relevant information of the first UE and relevant information of the second UE. The content of the first information can refer to the above. Alternatively, the first information can also include first sub-information and second sub-information, the first sub-information is used to indicate relevant information of the first UE, and the second sub-information is used to indicate relevant information of the second UE. In S406, the IMS network element can send the first sub-information and the second sub-information to the first core network network element respectively. For example, the first sub-information can indicate one or more of the following: the first identifier of the first UE, descriptive information of the call data between the first UE and the second UE, the first UE performs a call, or the first UE can exchange call data on the satellite. The second sub-information can indicate one or more of the following: the first identifier of the second UE, descriptive information of the call data between the first UE and the second UE, the second UE performs a call, or the second UE can exchange call data on the satellite.

[0233] Optionally, whether the decision of whether the first UE and the second UE can exchange call data on the satellite is made by the IMS network element, or whether the decision of whether the first UE and the second UE can exchange call data on the satellite is made by the first core network element, this decision process can be executed in the corresponding scenario. Optionally, the decision logic of the IMS network element can also be used for the first core network element to make a decision, or the first core network element can also use the decision logic of the IMS network element introduced above to decide whether the call data of the first UE and the second UE can be exchanged on the satellite. There is no limitation on this and no further details are given. Optionally, the IMS network element or the first core network element can decide whether the first UE and the second UE can exchange call data on the satellite when one or more of the following conditions are met: the call between the first UE and the second UE corresponds to a delay processing strategy, the call between any UEs corresponds to a delay processing strategy, the network needs to perform delay control, or disaster recovery factors. The delay handling strategy corresponding to the call between the first UE and the second UE, or the delay handling strategy corresponding to the call between any UEs, may be due to network factors and / or service factors, such as the need for network delay control, network congestion, or a certain call service or the call service of certain UEs being a call service with higher priority or importance, etc., and the network can perform delay control for this purpose. Exchanging call data between the first UE and the second UE on a satellite can significantly reduce the delay, and is therefore a delay control strategy. Alternatively, if a disaster occurs, such as an earthquake or tsunami, the importance or priority of the call service increases, and it is desired to minimize the call delay to improve call quality. Therefore, the network can decide whether the first UE and the second UE can exchange call data on the satellite. If the first UE and the second UE exchange call data on the satellite, the delay can be significantly reduced.

[0234] Optionally, after receiving the first information, the first core network element may further send a response message to the IMS network element, for example, response message 2, in response to the first information. If the IMS network element decides that the first UE and the second UE will exchange call data over the satellite, response message 2 may indicate successful reception of the first information, or indicate that the first UE and the second UE have been configured to exchange call data over the satellite, or indicate that configuration for exchanging call data over the satellite between the first UE and the second UE has failed. Alternatively, if the first core network element decides whether the first UE and the second UE will exchange call data over the satellite, response message 2 may indicate successful reception of the first information, or indicate that the first UE and the second UE will exchange call data over the satellite, or indicate that the first UE and the second UE will not exchange call data over the satellite. Optionally, if the response message indicates that the first UE and the second UE will not exchange call data over the satellite, the IMS network element may configure the call data to pass through the IMS network when transmitted between the first UE and the second UE.

[0235] S407: The first core network element sends first configuration information to the UPF. Accordingly, the UPF receives the first configuration information from the first core network element. For example, the first core network element may send the first configuration information to the UPF based on the first information.

[0236] Optionally, if the first core network element is an SMF, the SMF may send an N4 rule to the UPF. The N4 rule may include (or indicate) first configuration information. The N4 rule may be used to configure the N4 session of the first UE and the N4 session of the second UE. Alternatively, if the first core network element is a PCF, the PCF may first send a PCC rule to the SMF. The PCC rule may include (or indicate) the first configuration information. After receiving the PCC rule, the SMF may send the first configuration information to the UPF. For example, the SMF sends an N4 rule to the UPF. The N4 rule may include (or indicate) the first configuration information. Optionally, the SMF may determine the first configuration information based on the first information from the IMS network element. For example, the SMF may determine the first UE based on a parameter used to indicate the first UE and determine the second UE based on a parameter used to indicate the second UE. Thus, the SMF may determine the IMS PDU session of the first UE and the corresponding UPF, as well as determine the IMS PDU session of the second UE and the corresponding UPF. The SMF may then send the first configuration information to the corresponding UPF. Optionally, the first configuration information corresponding to the calling UE (e.g., the first UE) and the first configuration information corresponding to the called UE (e.g., the second UE) may be different. In addition, the SMF may also determine the data flow to be UPF locally switched based on the description information of the call data in the first information.

[0237] The first configuration information can configure the UPF to perform local switching of call data between the first UE and the second UE, or configure the UPF to directly forward the call data between the first UE and the second UE. This can be understood as the UPF being configured according to the first configuration information, for example, configuring the N4 session of the first UE and the N4 session for the second UE, so that when the UPF receives call data from the first UE (and the destination is the second UE), it directly forwards it to the second UE without passing through other network elements; similarly, when the UPF receives call data from the second UE (and the destination is the first UE), it directly forwards it to the first UE without passing through other network elements. If different UPFs serve the first UE and the second UE, the UPF described in S407 can be any one of them.

[0238] The first configuration information includes, for example, rules for filtering data and / or rules for forwarding data, wherein the rules for filtering data include, for example, packet detection rules (PDRs), and the rules for forwarding data include, for example, forwarding action rules (FARs).

[0239] As an implementation of PDR, for call data from a call device (or a communication apparatus), the PDR can be used to filter out call data between a first UE and a second UE (for example, filtering out data from a QoS flow with 5QI=1 on an IMS PDU session (voice call data), and data from a QoS flow with 5QI=2 (video call data)), wherein the call device is the first UE or the second UE. For example, the source interface in the PDR is the "access side", and the core network (CN) tunnel information in the PDR is the tunnel header with 5QI=1 of the PDU session.

[0240] As another implementation of PDR, for call data received by UPF and forwarded by UPF, the destination address of the call data included in the PDR can be the address information of the call peer device (or, the communication peer device). Wherein, if the call data comes from the first UE, the call peer device is the second UE; or, if the call data comes from the second UE, the call peer device is the first UE. For example, the source interface in the PDR is "IMS call internal", and / or, the destination address of the call data in the PDR is the address of the call peer device, so that the UPF can forward the call data between the first UE and the second UE directly to the call peer device.

[0241] As an implementation of FAR, the FAR can indicate that call data from the call device is forwarded to the UPF. For example, if the destination interface in the FAR is "IMS call internal", it means forwarding to the UPF.

[0242] As another implementation of the FAR, the UPF can forward call data received by the UPF to the call's peer device. For example, the FAR may specify the destination interface as "access side" and / or the out header as N3 tunnel or N9 tunnel information.

[0243] After receiving the first configuration information, the UPF can be configured according to the first configuration information, for example, configuring the local switching of the call data between the first UE and the second UE. For example, the configuration of the UPF includes one or more of the following: for call data from the call device, setting the rule for filtering data to filter out the call data between the first UE and the second UE (for example, data from the QoS flow with 5QI=1 on the IMS PDU session (voice call data), data from the QoS flow with 5QI=2 (video call data)), where the call device is the first UE or the second UE; or, for call data from the call device, setting the rule for forwarding data to forward to the UPF; or, for call data received by the UPF and forwarded from the UPF, setting the destination address of the call data to the address information of the call peer device, where if the call data comes from the first UE, the call peer device is the second UE, or if the call data comes from the second UE, the call peer device is the first UE; or, for call data received by the UPF and forwarded from the UPF, setting the rule for forwarding call data to forward to the call peer device.

[0244] The UPF sets the data filtering rules to filter out the call data between the first UE and the second UE. For example, the UPF sets the source interface in the PDR to "access side" and sets the CN tunnel information in the PDR to the tunnel header with a 5QI of 1 for the PDU session. With this setting, if there is call data from the first UE to be sent to the second UE, or call data from the second UE to be sent to the first UE, the UPF can filter out the call data for further processing.

[0245] The UPF sets the rule for forwarding data to forward to the UPF, for example, the UPF sets the destination interface in the FAR to "IMS call internal". Through this setting, the UPF can forward the call data from the first UE to be sent to the second UE (for example, the call data filtered by the above-mentioned PDR) to the UPF. Similarly, the UPF can also forward the call data from the second UE to be sent to the first UE (for example, the call data filtered by the above-mentioned PDR) to the UPF. This is equivalent to the UPF not forwarding the call data between the first UE and the second UE directly to other network elements, but first forwarding the call data to the UPF.

[0246] Since the UPF forwards the call data to this UPF, the UPF can receive the call data from the UPF. The UPF can then further configure the call data, for example, by configuring rules for filtering the call data and / or forwarding the call data. The rules for filtering the call data may include, for example, a PDR. For example, the UPF may set the source interface in the PDR corresponding to the call data to "IMS call internal" and / or set the destination address of the call data in the PDR to the address of the other device, thereby enabling the UPF to forward the call data directly to the other device. For example, if the same UPF serves the first and second UEs, the UPF may set the destination address of the call data to the address of the other device. Alternatively, if different UPFs serve the first and second UEs, the UPF may set the destination address of the call data to the address of the UPF serving the other device. The UPF can then forward the call data to the UPF serving the other device, which in turn forwards the call data to the other device. The rules for forwarding call data include, for example, the FAR. For example, the UPF may set the destination interface in the FAR to "access side" and / or set the out header in the FAR to N3 tunnel or N9 tunnel information. Through this configuration process, the UPF can forward call data from the first UE directly to the second UE, or to the UPF serving the second UE, and also forward call data from the second UE directly to the first UE, or to the UPF serving the first UE. For example, if the UPF serving the first and second UEs is deployed on a satellite, call data between the first and second UEs can be exchanged on the satellite.

[0247] Optionally, if the first core network element or IMS network element determines that the first UE and the second UE exchange call data over a satellite, and the UPF implements local switching, S407 may be executed. Alternatively, if the first core network element determines that the first UE and the second UE exchange call data over a satellite, and the first core network element determines that the RAN implements local switching, S407 may be replaced by the first core network element sending second configuration information to the RAN, and the RAN accordingly receives the second configuration information from the first core network element. If different RANs serve the first UE and the second UE, the first core network element may send the second configuration information to either RAN, or to both RANs. For example, if the first core network element is an SMF, the SMF may send N2 session management (SM) information to the RAN. The N2 SM information may include (or indicate) the second configuration information. The second configuration information may be used to configure an IMS PDU session for the first UE and an IMS PDU session for the second UE. For another example, if the first core network element is a PCF, the PCF may send a PCC rule to the SMF, where the PCC rule may include (or indicate) the second configuration information. The SMF then sends the second configuration information to the RAN. For example, the SMF sends N2 SM information to the RAN, where the N2 SM information may include (or indicate) the second configuration information.

[0248] As an optional implementation of the second configuration information, the second configuration information may configure an association between a QoS flow of the first UE and a QoS flow of the second UE. The QoS flow of the first UE is used to transmit call data between the first UE and the second UE, while the QoS flow of the second UE is used to transmit call data between the first UE and the second UE. This association enables the RAN to specify that data from the first UE in the QoS flow is forwarded directly to the second UE or to the UPF serving the second UE via the QoS flow of the second UE; and that data from the second UE in the QoS flow is forwarded directly to the first UE or to the UPF serving the first UE via the QoS flow of the first UE. For example, if the second configuration information configures an association between QoS flow 1 of the first UE and QoS flow 2 of the second UE, then when the RAN receives data from QoS flow 1 of the first UE, it can directly send it to the second UE or to the UPF serving the second UE via QoS flow 2 of the second UE. Alternatively, when the RAN receives data from the second UE in QoS flow 1, it can directly send it to the first UE or to the UPF serving the first UE via QoS flow 2 of the first UE.

[0249] Optionally, the method may further include the following S408 to S412, wherein the IMS network element in these steps is, for example, a P-CSCF, and the first core network element is, for example, a PCF.

[0250] S408: The IMS network element sends a second request to the second UE. Correspondingly, the second UE receives the second request from the IMS network element. The second request is, for example, a SIP invite message, which may request the second UE to accept a call with the first UE.

[0251] S409. The second UE sends a response message to the IMS network element. This is a response message to the second request after the second UE receives it. For example, a SIP 183 message. Accordingly, the IMS network element receives the SIP 183 message from the second UE. The SIP 183 message may indicate that the second UE accepts the call with the first UE, or may indicate that the second UE receives the SIP invite message request. The SIP 183 message may include, for example, a Session Description Protocol (SDP) answer.

[0252] S410: The IMS network element triggers the PCF to establish a QoS flow for the first UE and the second UE for carrying call data. For example, the QoS flow is a guaranteed bit rate (GBR) QoS flow with 5QI=1.

[0253] Optionally, the SMF may establish a QoS flow of 5QI=1 for the first UE and the second UE for transmitting voice call data and / or a QoS flow of 5QI=2 for transmitting video call data and / or other QoS flows for transmitting data channel communication data. This step may occur after S410, or before S411, or after S411, or before S412.

[0254] S411: The IMS network element sends a SIP 183 message to the first UE. Correspondingly, the first UE receives the SIP 183 message from the IMS network element. The SIP 183 message, for example, instructs the second UE to accept the call with the first UE.

[0255] S412: The first UE and the second UE have a conversation.

[0256] The call data sent by the first UE can reach the UPF or RAN, which can then forward the call data to the second UE, or to the UPF or RAN serving the second UE, which can then be forwarded by the UPF or RAN to the second UE. Similarly, the call data sent by the second UE can reach the UPF or RAN, which can then forward the call data to the first UE, or to the UPF or RAN serving the first UE, which can then be forwarded by the UPF or RAN to the first UE.

[0257] Alternatively, the above S406 may be executed before, after, or simultaneously with the execution of S410. For example, after receiving SIP 183 (S409) from the second UE, the IMS network element may execute S410, wherein the IMS network element may execute S406 before, during, or after the execution of S410. This is equivalent to the IMS network element triggering the PCF to establish a call bearer (e.g., a QoS flow with 5QI=1 and / or a QoS flow with 5QI=2 and / or other QoS flows for transmitting data channel communication data), indicating that the data on the bearer is directly exchanged on the satellite to the opposite UE, and the SMF may also simultaneously configure the UPF to perform local switching when establishing the call bearer. For this, please refer to Figure 4B. Figures 4A and 4B are both flowcharts of embodiments of the present application, the difference being that the order of some steps may be different.

[0258] In the embodiments of the present application, the UPF or RAN can locally exchange call data between a first UE and a second UE, both of which access the network via satellite. For example, the UPF or RAN can exchange call data between the first UE and the second UE on the satellite. This allows call data to be exchanged on the satellite without having to be routed to the terrestrial network, shortening the call data transmission path and reducing latency. Furthermore, because the UPF or RAN can perform local exchange of call data between devices, the call data can directly reach the other end device from the UPF or RAN without having to be transmitted through network elements such as IMS network elements, further shortening the transmission path and reducing latency.

[0259] Next, an embodiment of the present application provides another communication method. Please refer to Figure 5A, which is a flowchart of the method.

[0260] S501: A first UE establishes a PDU session. The PDU session can be used to carry IMS communication-related signaling and data, and is therefore also referred to as an IMS PDU session.

[0261] For more details about S501 , please refer to S401 in the embodiment shown in FIG. 4A or FIG. 4B .

[0262] S502: The first UE performs IMS registration.

[0263] For more details about S502 , please refer to S402 in the embodiment shown in FIG. 4A or FIG. 4B .

[0264] S503: The second UE establishes a PDU session. Similarly, the PDU session may also be referred to as an IMS PDU session.

[0265] For more details about S503 , please refer to S403 in the embodiment shown in FIG. 4A or FIG. 4B .

[0266] S504: The second UE performs IMS registration.

[0267] For more details about S504 , please refer to S404 in the embodiment shown in FIG. 4A or FIG. 4B .

[0268] The above steps S501 to S504 may be optional steps. For example, if the UE can make calls without registration, it is not necessary to perform any one or more steps S501 to S504.

[0269] The above is the registration process of two UEs. The following describes the call process between UEs.

[0270] S505: The first UE sends a first request to the IMS network element. Correspondingly, the IMS network element receives the first request from the first UE.

[0271] For more details about S505 , please refer to S405 in the embodiment shown in FIG. 4A or FIG. 4B .

[0272] S506: The IMS network element determines whether the first UE and the second UE exchange call data on the satellite, or determines whether the first UE and the second UE meet the conditions for exchanging call data on the satellite.

[0273] In the embodiment of the present application, an IMS network element determines whether a first UE and a second UE exchange call data over a satellite, or determines whether the first UE and the second UE meet conditions for exchanging call data over a satellite. The IMS network element may be, for example, a P-CSCF, an S-CSCF, or another network element within the IMS.

[0274] Optionally, the IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may include: determining that the first UE and the second UE are served by the same UPF, which is deployed on the satellite, and / or determining that the first UE and the second UE are served by the same IMS network element.

[0275] Alternatively, if the IMS network element determines that the first UE and the second UE meet the conditions for exchanging call data on the satellite, the conditions may include: the first UE and the second UE are served by the same UPF, which is deployed on the satellite, and / or the first UE and the second UE are served by the same IMS network element.

[0276] In the embodiment of the present application, since there is no further confirmation process by the core network element, if the IMS network element determines that the first UE and the second UE are served by different UPFs, it cannot determine whether a data transmission channel can be established between the two UPFs. In order to improve the success rate of exchanging call data between the first UE and the second UE over the satellite, in this case, the IMS network element may determine that the first UE and the second UE cannot exchange call data over the satellite. Only when the first UE and the second UE are served by the same UPF can the IMS network element determine that the first UE and the second UE can exchange call data over the satellite.

[0277] Optionally, the IMS network element determines that the first UE and the second UE exchange call data on the satellite, and may also include: determining that the media description information supported by the first UE and the second UE matches. For example, in addition to determining whether the first UE and the second UE are served by the same UPF, which is deployed on the satellite, and / or determining whether the first UE and the second UE are served by the same IMS network element, the IMS network element may also determine whether the media description information of the first UE and the second UE matches. In a traditional call process, when the call data passes through the IMS, the IMS network element may perform format conversion on the call data. For example, the media description information of the UEs on both sides of the call may not match. Through the processing of the IMS network element, the call peer end can identify the received call data. In the embodiment of the present application, the call data between the first UE and the second UE may not pass through the IMS, but directly reach the call peer end (the first UE or the second UE). Therefore, optionally, the media description information of the first UE and the second UE can match, so that the first UE and the second UE can identify the call data from the call peer end without processing by the IMS network element. Optionally, if the media description information of the first UE and the second UE do not match, the IMS network element may determine that the first UE and the second UE cannot exchange call data over the satellite.

[0278] For more details about S506 , such as how the IMS network element determines whether the first UE and the second UE exchange call data on the satellite, please refer to the relevant introduction of the embodiment shown in FIG. 4A or FIG. 4B .

[0279] Alternatively, the IMS network element may not need to determine whether the first UE and the second UE can exchange call data over the satellite, but may instead directly configure the first UE and the second UE to exchange call data over the satellite. Therefore, step S506 is optional. For example, the IMS network element may execute steps S507 and other steps described below without making a determination. If this determination is not performed, the failure rate of the first UE and the second UE exchanging call data over the satellite may increase because the first UE and the second UE may not actually meet the conditions for exchanging call data over the satellite. However, not making a determination can save time and improve the efficiency of UE call execution.

[0280] S507. The IMS network element sends the address information of the second UE to the first UE. Accordingly, the second UE receives the address information from the IMS network element. The IMS network element sends the address information of the first UE to the second UE. Accordingly, the first UE receives the address information from the IMS network element. This is equivalent to the IMS network element sending the address information of the other device to both devices of the call.

[0281] If the IMS network element is an S-CSCF, the S-CSCF may first send the corresponding address information to the P-CSCF, which then sends the address information to the corresponding UE. If the IMS network element is a P-CSCF, the P-CSCF may send the corresponding address information to the corresponding UE. Taking the IMS network element as an example, the P-CSCF may send a second request to the second UE. The second request may be, for example, a SIP invite message. The SIP invite message may include the address information of the first UE, such as the IP address of the first UE. In addition, the P-CSCF may send a SIP 183 message to the first UE. The SIP 183 message may include the address information of the second UE, such as the IP address of the second UE.

[0282] The IMS network element may obtain the address information of the first UE through a request from the first UE. The request of the first UE may include, for example, the first request described in the embodiment shown in FIG. 4A or FIG. 4B , or include a SIP registration message sent by the first UE to the IMS network element in S502. The first request may be, for example, a SIP invite message. The SIP invite message or the SIP registration message may be implemented in the form of a data packet. The data packet may carry source address information. The source address information may be, for example, address information of the first UE in a private network. For example, the source address information may be carried in a message body (e.g., a payload) of the data packet. Alternatively, the source address information may be address information of the first UE in a public network. For example, the UPF serving the first UE may allocate an address in the public network to the first UE. The address information in the public network may be carried in an IP header of the data packet.

[0283] Please refer to Figure 5B, which is an example of the address information carried by the data packet corresponding to the SIP message of the first UE in an embodiment of the present application. In Figure 5B, the IP address obtained when the first UE establishes an IMS PDU session is a private network address. When the data packet of the first UE reaches the UPF, the UPF performs NAT as an example. When the first UE sends a data packet (or SIP message), the address information of the first UE in the private network is carried in the message body of the SIP message. At the same time, the address information is also included in the IP header of the data packet. For example, the address information is IP-1 as shown in Figure 5B. When the data packet arrives at the UPF, the UPF can perform NAT on the address information in the IP header of the data packet and convert it into an address in the public network. For example, the converted address information is IP-2. Then, the source address information in the IP header of the data packet sent by the UPF to the IMS network element is IP-2, and the source address information carried in its message body is still IP-1. After the data packet arrives at the IMS network element, the IMS network element can determine that the source address information in the IP header of the data packet is different from the source address information in the message body of the data packet. Therefore, it can be determined that the IP address of the first UE has been NATed at the UPF, so that the IP address of the first UE stored in the IMS network element can include at least one of IP1 or IP2. Accordingly, in S507, the IMS network element sends the address information of the first UE to the second UE, and can send IP1 and / or IP2 to indicate (or as) the IP address of the first UE. If the IP address obtained when the first UE establishes the IMS PDU session is a public network address, then when the data packet of the first UE arrives at the UPF, the UPF may not perform NAT. Therefore, taking IP1 as the IP address in the message body of the SIP message received by the IMS network element and IP2 as the source address in the header of the data packet carrying the SIP message received by the IMS network element as an example, IP1 and IP2 can be the same or different.

[0284] Similarly, the IMS network element can obtain the address information of the second UE through a request from the second UE. The request from the second UE, for example, includes a SIP registration message sent by the second UE to the IMS network element in S402. The SIP registration message can be implemented in the form of a data packet, which can carry source address information. The source address information can be, for example, the address of the second UE in a private network. Alternatively, the source address information can be the address information of the second UE in a public network. For example, the UPF serving the second UE can allocate an address in the public network to the second UE, and the address information in the public network can be carried in the IP header of the data packet. Accordingly, in S507, the IMS network element sends the address information of the second UE to the first UE. The IP address in the message body of the SIP message received by the IMS network element from the second UE and / or the source address in the header of the data packet carrying the SIP message from the second UE can be used to indicate (or serve as) the IP address of the second UE.

[0285] Optionally, in S507, the IMS network element may send the address information of the first UE to the second UE. After receiving the address information, the second UE may send a SIP 183 message to the IMS network element. The IMS network element may trigger the first core network element (e.g., PCF) to establish a QoS flow for carrying call data for the first UE and the second UE. The QoS flow is, for example, a GBR type QoS flow with 5QI=1. Afterwards, the IMS network element may send the address information of the second UE to the first UE. For this part, please refer to S408 to S411 in the embodiment shown in Figure 4A or Figure 4B.

[0286] S508: The first UE and the second UE have a conversation.

[0287] For example, in the embodiment of the present application, the call data between the first UE and the second UE can be locally exchanged in the UPF. When the first UE sends call data to the second UE, the destination address carried by the call data can be the address information of the second UE. After receiving the call data, the UPF can directly send the call data to the second UE based on the destination address, without passing through other network elements such as the IMS network element. Similarly, when the second UE sends call data to the first UE, the destination address carried by the call data can be the address information of the first UE. After receiving the call data, the UPF can directly send the call data to the first UE based on the destination address, without passing through other network elements such as the IMS network element.

[0288] The UPF in the embodiment of the present application can locally exchange call data between the first UE and the second UE. Both the first UE and the second UE access the network via a satellite. For example, the UPF can exchange call data between the first UE and the second UE on the satellite. As a result, call data can be exchanged on the satellite without having to be routed to the ground network, shortening the transmission path of the call data and reducing latency. Since the UPF can perform local exchange of call data between devices, the call data can directly reach the call counterpart device from the UPF without having to be transmitted through network elements such as the IMS network element, thereby further shortening the transmission path and reducing latency. In addition, the IMS network element can send the address information of the devices of both parties to the call to the communication counterpart device, so that the devices of both parties can carry the address of the call counterpart device during the call to exchange call data on the satellite, without having to perform excessive configuration of the core network network elements and / or RAN, etc., which can reduce the network element configuration process and improve call efficiency.

[0289] The following continues to introduce the method provided by the embodiment of the present application. In the method introduced below, the first core network network element involved can be the SMF shown in any of Figures 3A to 3E. In the following introduction, taking the first core network network element being the SMF as an example, for example, the first core network network element serving the first UE is the SMF serving the IMS PDU session of the first UE, which can be referred to as the first SMF; the first core network network element serving the second UE is the SMF serving the IMS PDU session of the second UE, which can be referred to as the second SMF. In the method introduced below, the second core network network element involved can be the PCF shown in any of Figures 3A to 3E. In the following introduction, taking the second core network network element being the PCF as an example, for example, the second core network network element serving the first UE is the PCF serving the first UE, or the PCF serving the IMS PDU session of the first UE, which can be referred to as the first PCF; the second core network network element serving the second UE is the PCF serving the second UE, or the PCF serving the IMS PDU session of the first UE, which can be referred to as the second PCF.

[0290] Next, an embodiment of the present application provides another communication method. Please refer to Figure 8, which is a flowchart of the method.

[0291] S801: A first UE establishes a PDU session. The PDU session can be used to carry IMS communication-related signaling and data, and is therefore also called an IMS PDU session. The anchor point UPF of the PDU session is located on the ground.

[0292] For more details about S801 , please refer to S401 in the embodiment shown in FIG. 4A or FIG. 4B .

[0293] S802: The first UE performs IMS registration.

[0294] For more details about S802 , please refer to S402 in the embodiment shown in FIG. 4A or FIG. 4B .

[0295] S803: The second UE establishes a PDU session. Similarly, the PDU session can also be called an IMS PDU session, and the anchor point UPF of the PDU session is located on the ground.

[0296] For more details about S803 , please refer to S403 in the embodiment shown in FIG. 4A or FIG. 4B .

[0297] S804: The second UE performs IMS registration.

[0298] For more details about S804 , please refer to S404 in the embodiment shown in FIG. 4A or FIG. 4B .

[0299] The above steps S801 to S804 may be optional steps. For example, if the UE can make calls without registration, it is not necessary to perform any one or more steps S801 to S804.

[0300] The above is the registration process of two UEs. The following describes the call process between UEs.

[0301] S805a: The first UE sends a first request to the first IMS network element. Correspondingly, the first IMS network element receives the first request from the first UE.

[0302] The first IMS network element is, for example, an IMS network element serving the first UE, a P-CSCF, or an S-CSCF, or may be other network elements within the IMS serving the first UE.

[0303] This document also relates to an IMS network element serving a second UE, which may be referred to as a second IMS network element. The second IMS network element may be, for example, a P-CSCF or an S-CSCF, or may be another network element within the IMS serving the second UE. The first IMS network element and the second IMS network element may be the same network element or different network elements.

[0304] If the IMS serving the first UE and the IMS serving the second UE are the same network element, the first IMS network element and the second IMS network element are the same network element; otherwise, the first IMS network element and the second IMS network element are different network elements.

[0305] The first request may be used to request a conversation with the second device, for example, called a call request or a conversation request, etc. For more details about S805a, please refer to S405 in the embodiment shown in FIG4A or FIG4B .

[0306] S806. The first IMS network element determines whether to allow the first UE and the second UE to exchange call data on the satellite based on the first condition; or, the first IMS network element determines whether the first UE meets the condition for exchanging call data on the satellite, for example, the condition is referred to as the first condition.

[0307] In various embodiments of the present application, exchanging call data on a satellite may also be understood or replaced by UE-satellite-UE (USU) communication, or understood or replaced by call data not returning to the ground network, or understood as performing local switching on a satellite, etc., without limitation.

[0308] The first IMS network element may execute S806 after receiving the first message, which may be, for example, the first request in S805a. The first request may be a request to conduct a call with the second UE, and may also be referred to as a call request or a conversation request. The first UE sends the first request, and the first request may reach the first IMS network element, as shown in S805a. The first IMS network element sends the first request to the second IMS network element, and the second IMS network element may receive the first request, as shown in S805b. In addition, the second IMS network element may also send the first request to the second UE, as shown in S805c. For more information about the first request, please refer to S405 in the embodiment shown in Figures 4A or 4B.

[0309] Alternatively, the first message may also be the response message in S818b, which is a response message to the first request. FIG8 takes this as an example.

[0310] For example, after receiving the first request, the first IMS network element may not temporarily execute S806. Instead, it may execute S806 after receiving a response message from the second UE. In this case, the response message may be referred to as a first message. The response message may be a response to the first request, for example, a SIP 183 (session progress message, sent by the called party to the calling party to indicate that a session is in progress), a SIP 180 (ringing message, sent by the called party to the calling party to indicate that the called party is ringing the user, and the calling party may generate a ringback tone for the user), or another response message. The first UE sends a message (e.g., a first request) requesting a call with the second UE. The first request may reach the first IMS network element (see S805a). The first IMS network element sends the first request to the second IMS network element, and the second IMS network element may receive the first request (see S805b). In addition, the second IMS network element may also send the first request to the second UE (see S805c). The first request may request a call with the second UE. After receiving the first request, the second UE can send a response message. When the response message arrives at the second IMS network element, the second IMS network element receives the response message, see S818a; the second IMS network element can send the response message to the first IMS network element, see S818b; the first IMS network element can send the response message to the first UE, see S818c.

[0311] Optionally, the first IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may include one or more of the following, or the first IMS network element may determine that the first UE and the second UE exchange call data on the satellite through one or more of the following: determining that the network allows the first UE to exchange call data on the satellite; or, determining that the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, determining that the first UE and the second UE are served by the same IMS network element; or, determining that the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, determining that the media description information supported (or adopted) by the first UE and the second UE matches; or, determining that the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN; or, determining that lawful interception is not performed on the call between the first UE and the second UE; or, determining that the first UE and the second UE are located on the same satellite; or, determining that the first UE and the second UE are located on different satellites, and there is an inter-satellite link (ISL) between the different satellites; or, determining that when the first UE is in a roaming state, the first UE does not perform home routing in the call. The first IMS network element needs to determine whether the network allows the first UE to exchange call data on the satellite, for example, based on the subscription information of the first UE and / or through information such as operator policy, without specific limitation.

[0312] Alternatively, the first condition may include one or more of the following: the network allows the first UE to exchange call data on the satellite; or, the first UE and the second UE are served by the same UPF, which is deployed on the satellite; or, the first UE and the second UE are served by the same IMS network element; or, the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, the media description information supported by the first UE and the second UE matches; or, the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN; or, no legal monitoring is performed on the call between the first UE and the second UE; or, the first UE and the second UE are located on the same satellite; or, the first UE and the second UE are located on different satellites, and there is an inter-satellite link between the different satellites; or, when the first UE is in roaming state, the first UE does not perform home routing in the call.

[0313] The above takes the example that the first IMS network element and the second IMS network element are different network elements. Alternatively, if the first IMS network element and the second IMS network element are the same network element, then the first IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may also include one or more of the following, or the first IMS network element may also determine that the first UE and the second UE exchange call data on the satellite through one or more of the following: determining that the first UE and the second UE are served by the same PCF; or, determining that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF; or, determining that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same SMF; or, determining that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF and by the same SMF; or, determining that the network allows the second UE to exchange call data on the satellite; or, determining that when the second UE is in roaming state, the second UE does not perform home routing in the call.

[0314] Alternatively, if the first IMS network element and the second IMS network element are the same network element, the first condition may also include one or more of the following: the first UE and the second UE are served by the same PCF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same SMF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF and by the same SMF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF and by the same SMF; or, the network allows the second UE to exchange call data on the satellite; or, when the second UE is in roaming state, the second UE does not perform home routing in the call.

[0315] The PCF serving a UE and the PCF serving the IMS PDU session for that UE may be the same PCF. For example, the PCF serving a UE may specifically refer to the PCF serving the IMS PDU session for that UE. The following description uses "the PCF serving the UE" as an example. Furthermore, the SMF serving a UE may specifically refer to the SMF serving the IMS PDU session for that UE. The following description uses "the SMF serving the UE" as an example.

[0316] As described above with respect to the first condition, if the first IMS network element and the second IMS network element are different network elements, the first IMS network element can determine information related to the first UE, but does not need to determine information related to the second UE and not related to the first UE (e.g., whether the second UE implements home routing or whether the network allows the second UE to exchange call data over a satellite). Similarly, the second IMS network element can determine information related to the second UE, but does not need to determine information related to the first UE and not related to the second UE (e.g., whether the first UE implements home routing or whether the network allows the first UE to exchange call data over a satellite). If the first IMS network element and the second IMS network element are the same network element, the first IMS network element can determine information related to the first UE and / or determine information related to the second UE.

[0317] The aforementioned first condition may include a condition related to the first PCF serving the first UE, and the first IMS network element may first obtain information about the first PCF. For example, the first IMS network element may request the UDM to obtain information about the first PCF; or, the first IMS network element may obtain information about the first PCF through a binding support function (BSF). For example, for a specific UE or a specific PDU session, the BSF may store one or more of the UE's identifier, the UE's IP address, the UE's data network name (DNN), the UE's slice information, or information about the PCF selected by the UE (such as information such as the PCF address and the associated PCF instance ID). Therefore, the first IMS network element may obtain information about the corresponding UE's PCF or information about the PCF corresponding to the UE's PDU session from the BSF through one or more of the above information. Alternatively, the first IMS network element may also obtain information about the first PCF through other means. Optionally, if the first IMS network element and the second IMS network element are the same network element, the aforementioned first condition may include a condition related to the second PCF serving the second UE, and the first IMS network element may also obtain information about the second PCF. For example, the first IMS network element may request the UDM to obtain information about the second PCF; alternatively, the first IMS network element may obtain information about the second PCF through the BSF, or the first IMS network element may obtain information about the second PCF through other means. The information about the first PCF may include, for example, an identifier of the first PCF and / or address information of the first PCF; the information about the second PCF may include, for example, an identifier of the second PCF and / or address information of the second PCF.

[0318] The aforementioned first condition may include a condition related to the first SMF serving the IMS PDU session of the first UE, and the first IMS network element may first obtain information about the first SMF. For example, the first IMS network element may request the UDM to obtain information about the first SMF; or, the first IMS network element may obtain information about the first SMF through the BSF. In this case, for a specific PDU session, the BSF may store one or more of the following: the identifier of the UE corresponding to the PDU session, the IP address of the UE, the DNN of the UE, the slice information of the UE, or information about the SMF selected by the UE (e.g., the address of the SMF and the associated SMF instance ID). Therefore, the first IMS network element may obtain information about the SMF corresponding to the corresponding UE's PDU session from the BSF using one or more of the above information. Alternatively, the first IMS network element may obtain information about the first SMF through other means. Optionally, if the first IMS network element and the second IMS network element are the same network element, the aforementioned first condition may include a condition related to the second SMF serving the second UE, and the first IMS network element may further obtain information about the second SMF. For example, the first IMS network element may request the UDM to obtain information about the second SMF; alternatively, the first IMS network element may obtain information about the second SMF through the BSF, or the first IMS network element may obtain information about the second SMF through other means. The information about the first SMF may include, for example, an identifier of the first SMF and / or address information of the first SMF; the information about the second SMF may include, for example, an identifier of the second SMF and / or address information of the second SMF.

[0319] The following introduces some of the contents included in the first condition.

[0320] For example, a UPF can be deployed on a satellite, or a satellite has the function of a UPF. If the first UE and the second UE are located under the same satellite, it can be considered that the first UE and the second UE can be served by the same UPF, and the UPF is deployed on the satellite.

[0321] If the first UE and the second UE are located under different satellites, it indicates that the first UE and the second UE are served by different UPFs, and the different UPFs are both located on the satellites. If there is an inter-satellite link between the different satellites, it can indicate that a data transmission channel can be established between the different UPFs.

[0322] If the first UE and the second UE are served by the same UPF, and that UPF is deployed on a satellite, the call data between the first UE and the second UE can be exchanged on the satellite. Alternatively, if the first UE and the second UE are served by different UPFs, and those different UPFs can communicate or establish a data transmission channel, the call data between the first UE and the second UE can be exchanged locally through the UPF. If both different UPFs are deployed on a satellite, the call data between the first UE and the second UE can be exchanged on the satellite.

[0323] Some current calls require lawful interception to enable behavioral control. Lawful interception is typically performed over terrestrial networks. Therefore, if a call is to be lawfully intercepted, it should be transmitted via a terrestrial path, rather than exchanging call data over a satellite. Whether a call of a first UE requires lawful interception can be determined by the first IMS network element serving the first UE. Therefore, if lawful interception is not required for the call between the first UE and the second UE, the call data corresponding to the call can be exchanged over a satellite. However, if lawful interception is to be performed on the call, the call data corresponding to the call should not be exchanged over a satellite.

[0324] If the first UE is in a roaming state, the first UE may or may not perform home routing (HPLMN routing) in a call with a second UE. Not performing home routing can also be understood as performing visited PLMN routing (VPLMN routing). If the first UE performs home routing in a call with a second UE, the transmission path of the call data must include a home path. In this case, the call data cannot be exchanged over the satellite. If the first UE does not perform home routing in a call with a second UE, the transmission path of the call data may not include a home path. In this case, the call data can be exchanged over the satellite.

[0325] If the PCF serving the first UE is different from the PCF serving the second UE, or the PCF of the IMS PDU session serving the first UE is different from the PCF of the IMS PDU session serving the second UE, then the first UE and the second UE may exchange call data on the satellite, which may involve information and policy interaction between the two PCFs. This increases the complexity of the system. Therefore, in an embodiment of the present application, if the PCF serving the first UE is different from the PCF serving the second UE, or the PCF of the IMS PDU session serving the first UE is different from the PCF of the IMS PDU session serving the second UE, then the first UE and the second UE may not exchange call data on the satellite; however, if the PCF serving the first UE and the PCF serving the second UE are the same, and the PCF of the IMS PDU session serving the first UE is the same as the PCF of the IMS PDU session serving the second UE, then the first UE and the second UE may exchange call data on the satellite.

[0326] If the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are different, the exchange of call data between the first UE and the second UE on the satellite may involve information interaction between the two SMFs. The embodiment of the present application can enable information interaction between SMFs. Then, whether the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are the same or not, it does not affect the exchange of call data between the first UE and the second UE on the satellite, that is, the first UE and the second UE can exchange call data on the satellite, or they may not exchange call data on the satellite. In this case, the conditions related to the SMF may not be included in the first condition. Alternatively, considering that the interaction between SMFs will also bring complexity to the system, the embodiment of the present application may also stipulate that if the first UE and the second UE want to exchange call data on the satellite, the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE should be the same. In this case, if the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are different, the first UE and the second UE may not exchange call data on the satellite; or, if the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are the same, the first UE and the second UE may exchange call data on the satellite.

[0327] Among them, if the embodiment of the present application stipulates that if the first UE and the second UE want to exchange call data on the satellite, the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE should be the same, then combined with the limitation of PCF, it can be understood that if the first UE and the second UE want to exchange call data on the satellite, the PCF serving the first UE and the PCF serving the second UE should be the same, the PCF of the IMS PDU session serving the first UE and the PCF of the IMS PDU session serving the second UE should be the same, and the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE should be the same. Then, if the first condition includes a condition related to the PCF and a condition related to the SMF, then, if one or more of the following is met, the first UE and the second UE may not exchange call data on the satellite: the PCF serving the first UE and the PCF serving the second UE are different, the PCF of the IMS PDU session serving the first UE and the PCF of the IMS PDU session serving the second UE are different, or the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are different; or, if the following are met, the first UE and the second UE may exchange call data on the satellite: the PCF serving the first UE and the PCF serving the second UE are the same, the PCF of the IMS PDU session serving the first UE and the PCF of the IMS PDU session serving the second UE are the same, and the SMF of the IMS PDU session serving the first UE and the SMF of the IMS PDU session serving the second UE are the same.

[0328] For more details about S806 , such as other conditions included in the first condition, please refer to the relevant introduction of the embodiment shown in FIG. 4A or FIG. 4B .

[0329] Alternatively, the first IMS network element may not need to determine whether the first UE and the second UE can exchange call data over the satellite, but may instead directly configure the first UE and the second UE to exchange call data over the satellite. Therefore, step S806 is optional. For example, the first IMS network element may execute steps S807 and other steps described below without making a determination. If this determination is not performed, the failure rate of the first UE and the second UE exchanging call data over the satellite may increase because the first UE and the second UE may not actually meet the conditions for exchanging call data over the satellite. However, not making a determination can save time and improve the efficiency of UE call execution.

[0330] S807: The first IMS network element sends a second message to the first PCF serving the first UE. Correspondingly, the first PCF receives the second message.

[0331] The first PCF and the second PCF serving the second UE may be the same, that is, they are the same PCF. In this case, the first PCF in S807 is the PCF. As previously mentioned, the first IMS network element and the second IMS network element may be the same network element, or they may be different network elements. Then, if the first IMS network element and the second IMS network element are the same network element (for example, the first IMS network element), the first IMS network element may send the second message and the third message to the first PCF; or, if the first IMS network element and the second IMS network element are different network elements, the first IMS network element may send the second message to the first PCF. In addition, the second IMS network element may send the third message to the first PCF, and the first PCF may receive the second message and the third message. When the first IMS network element and the second IMS network element are the same, the first IMS network element sends the second message and the third message to the first PCF. This can be understood as the first IMS network element requesting USU communication for the first UE and the second UE respectively, and the contents of the second message and the third message may not be exactly the same. In addition, if the first IMS network element and the second IMS network element are the same, and the first PCF and the second PCF are the same, then optionally, the first IMS network element can combine the second message and the third message into one message and send it, for example, carry the information included in the second message and the information included in the third message in one message and send it.

[0332] Optionally, the second message may also be called a UE policy request, or may have other names. The second message may include an identifier of the first UE, an identifier of the second UE, and fourth information. The fourth information may be used to request the first UE and the second UE to exchange call data on the satellite. For example, the fourth information may also be called a USU communication request (the USU communication request may be considered as a USU communication request for the first UE, or as a USU communication request for the first UE and the second UE), etc., and there is no limitation on the name.

[0333] The identifier of the first UE may include one or more of the first identifier of the first UE, the second identifier of the first UE, or the third identifier of the first UE, and may also include other identifiers of the first UE. The identifier of the second UE may include one or more of the first identifier of the second UE, the second identifier of the second UE, or the third identifier of the second UE, and may also include other identifiers of the second UE. The third identifier of the UE, for example, includes address information of the UE, such as the IP address of the UE. For example, the third identifier of the first UE may include the IP address of the first UE; the third identifier of the second UE may include the IP address of the second UE. In addition, for an introduction to the first identifier and the second identifier, please refer to the embodiment shown in Figure 4A or Figure 4B.

[0334] If the first IMS network element determines in S806 that the first UE and the second UE exchange call data on the satellite, S807 may be executed; alternatively, if the first IMS network element determines in S806 that the first UE and the second UE do not exchange call data on the satellite, S807 may not be executed.

[0335] S808. The second IMS network element determines whether to allow the first UE and the second UE to exchange call data on the satellite based on the first condition; or, the second IMS network element determines whether the first UE meets the condition for exchanging call data on the satellite, for example, the condition is referred to as the first condition.

[0336] The second IMS network element may execute S808 after receiving the first message. For the second IMS network element, as an optional implementation of the first message, the first message may, for example, originate from the first UE. This first message may be, for example, the first request in S805b. The first UE sends the first request, which may reach the first IMS network element (see S805a). The first IMS network element sends the first request to the second IMS network element, which may receive the first request (see S805b). Furthermore, the second IMS network element may also send the first request to the second UE (see S805c).

[0337] Alternatively, as another optional implementation of the first message, the first message comes from the second UE, such as the response message in S818a, and Figure 8 takes this as an example. The response message may be a response to a message for requesting a call with the second UE, such as a response to the first request. Among them, the first UE sends a message (such as a first request) for requesting a call with the second UE, and the first request may reach the first IMS network element, refer to S805a; the first IMS network element sends the first request to the second IMS network element, and the second IMS network element may receive the first request, refer to S805b; in addition, the second IMS network element may also send the first request to the second UE, refer to S805c. The first request may request a call with the second UE. After receiving the first request, the second UE can send a response message. When the response message arrives at the second IMS network element, the second IMS network element receives the response message, see S818a; the second IMS network element can send the response message to the first IMS network element, see S818b; the first IMS network element can send the response message to the first UE, see S818c.

[0338] Optionally, the second IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may include one or more of the following, or the second IMS network element may determine that the first UE and the second UE exchange call data on the satellite by one or more of the following: determining that the network allows the second UE to exchange call data on the satellite; or, determining that the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, determining that the first UE and the second UE are served by the same IMS network element; or, determining that the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, determining The first UE and the second UE may match the media description information supported by the first UE and the second UE; or determine that the serving PLMN of the first UE and the serving PLMN of the second UE are the same PLMN; or determine that lawful interception is not performed on the call between the first UE and the second UE; or determine that the first UE and the second UE are located on the same satellite; or determine that the first UE and the second UE are located on different satellites and that there is an inter-satellite link between the different satellites; or determine that when the second UE is in a roaming state, the second UE does not perform home routing for the call; or determine that the first UE and the second UE are served by the same PCF; or determine that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF; or determine that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF and the same SMF; or determine that the first UE and the second UE are served by the same PCF and the same SMF. The second IMS network element may determine whether the network allows the second UE to exchange call data on the satellite, for example, based on the subscription information of the first UE and / or information such as operator policy, without limitation.

[0339] Alternatively, the first condition may include one or more of the following: the network allows the second UE to exchange call data on the satellite; or, the first UE and the second UE are served by the same UPF, which is deployed on the satellite; or, the first UE and the second UE are served by the same IMS network element; or, the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, the media description information supported by the first UE and the second UE matches; or, the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN; or, no legal interception is performed on the call between the first UE and the second UE; or, the first UE and the second UE are located under the same satellite; or, the first UE and the second UE are located under different satellites, and there is an inter-satellite link between the different satellites; or, when the second UE is in a roaming state, the second UE does not perform home routing in the call; or, the first UE and the second UE are served by the same PCF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF; or, the first UE and the second UE are served by the same PCF and by the same SMF; or, the IMS PDU session of the first UE and the IMS A PDU session is served by the same PCF and by the same SMF.

[0340] The above example assumes that the first IMS network element and the second IMS network element are different network elements. If they are the same network element, S808 may not be executed, and S806 may be executed instead. For details, please refer to the introduction of S806.

[0341] For more information about S808, such as the first condition, etc., please refer to the introduction of S806.

[0342] S809: The second IMS network element sends a third message to the second PCF serving the second UE. Correspondingly, the second PCF receives the third message.

[0343] Among them, the first PCF and the second PCF serving the second UE can be the same, that is, the two are the same PCF, and the following embodiments of this application will take this as an example. In this case, the second PCF in S809 and the first PCF in S807 both refer to the same PCF. As mentioned above, the first IMS network element and the second IMS network element can be the same network element, or they can be different network elements. Then, if the first IMS network element and the second IMS network element are the same network element (for example, the first IMS network element), the first IMS network element can send the second message and the third message to the first PCF; or, if the first IMS network element and the second IMS network element are different network elements, the first IMS network element can send the second message to the first PCF, and the second IMS network element can send the third message to the first PCF.

[0344] Optionally, the third message may also be called a UE policy request, or may have other names. The third message may include an identifier of the first UE, an identifier of the second UE, and fourth information. The fourth information may be used to request the first UE and the second UE to exchange call data on the satellite. For example, the fourth information may also be called a USU communication request (the USU communication request may be considered as a USU communication request for the second UE, or as a USU communication request for the first UE and the second UE), etc., and there is no limitation on the name.

[0345] The identifier of the first UE may include the first identifier of the first UE, the second identifier of the first UE, or the third identifier of the second UE, and may also include other identifiers of the first UE. The identifier of the second UE may include the first identifier of the second UE, the second identifier of the second UE, or the third identifier of the second UE, and may also include other identifiers of the second UE. The third identifier of the UE may, for example, include address information of the UE, such as the IP address of the UE. For example, the third identifier of the first UE may include the IP address of the first UE; the third identifier of the second UE may include the IP address of the second UE. For an introduction to the first identifier and the second identifier, etc., please refer to the embodiment shown in Figure 4A or Figure 4B.

[0346] If the second IMS network element determines in S808 that the first UE and the second UE exchange call data on the satellite, S809 may be executed; otherwise, if the second IMS network element determines in S808 that the first UE and the second UE do not exchange call data on the satellite, S809 may not be executed.

[0347] S810: The first PCF sends fifth information to the first SMF based on the second condition. Correspondingly, the first SMF receives the fifth information.

[0348] For example, the first PCF may determine whether to allow the first UE and the second UE to exchange call data on the satellite based on the second condition. If the first UE and the second UE are allowed to exchange call data on the satellite (or the second condition is met), the first PCF sends the fifth information to the first SMF. If the first UE and the second UE are not allowed to exchange call data on the satellite (or the second condition is not met), the first PCF may not send the fifth information to the first SMF. This embodiment of the application takes the first PCF and the second PCF as the same PCF as an example, and the following description will be based on the first PCF.

[0349] Optionally, the second condition includes one or more of the following: the PCF serving the first UE is the same as the PCF serving the second UE; or, the PCF of the IMS PDU session serving the first UE is the same as the PCF of the IMS PDU session serving the second UE; or, the SMF of the IMS PDU session serving the first UE is the same as the SMF of the IMS PDU session serving the second UE; or, both the first UE and the second UE access the network via satellite; the first UE and the second UE are located on the same satellite; or, the first UE and the second UE are located on different satellites, and there is an inter-satellite link between the different satellites.

[0350] Optionally, the first PCF can determine whether the first PCF serving the first UE and the second PCF serving the second UE are the same (or, whether they are the same PCF). The second message may include the identifier of the first UE and the identifier of the second UE. The first PCF can determine whether the first PCF is the PCF serving the first UE (or, whether it is the PCF serving the IMS PDU session of the first UE) based on the identifier of the first UE. In addition, the first PCF can determine whether the first PCF is the PCF serving the second UE (or, whether it is the PCF serving the IMS PDU session of the second UE) based on the identifier of the second UE. If the first PCF is both the PCF serving the first UE (or, the PCF serving the IMS PDU session of the first UE) and the PCF serving the second UE (or, the PCF serving the IMS PDU session of the second UE), the first PCF can determine that the first PCF and the second PCF are the same, or determine that the first PCF serves the first UE and the second UE.

[0351] Optionally, the first PCF may determine whether the first SMF serving the first UE and the second SMF serving the second UE are the same (or whether they are the same SMF). For example, the first PCF may determine the first SMF based on the identifier of the first UE and the second SMF based on the identifier of the second UE, thereby determining whether the first SMF and the second SMF are the same SMF.

[0352] The first condition is introduced in both S806 and S808, and the second condition can be included in the first condition. Therefore, optionally, the first PCF may not have to judge the second condition. For example, the first PCF may send the fifth information to the first SMF without judging the second condition. Alternatively, regardless of whether the first IMS network element has judged the first condition, the first PCF may judge the second condition again. Alternatively, optionally, if the first PCF judges the second condition, the first IMS network element may not have to judge the first condition (or, it is not necessary to judge the items in the first condition that are similar or related to the second condition). Which network element specifically judges the corresponding condition may be the default of the communication system, or predefined by the protocol, or determined by negotiation between network elements, or stipulated by the operator's policy.

[0353] Optionally, if the first PCF determines that the second condition is met and the first PCF receives the second message from the first IMS network element and the third message from the second IMS network element (or, if the first IMS network element and the second IMS network element are the same IMS network element, the first PCF can receive the second message and the third message from the IMS network element), the first PCF believes that the first UE and the second UE can exchange call data on the satellite, and the first PCF can execute S810. Alternatively, if one or more of the following conditions are met, the first PCF considers that the first UE and the second UE cannot exchange call data on the satellite, and the first PCF may not execute S810: the second condition is not met, the first PCF does not receive the second message from the first IMS network element and / or the third message from the second IMS network element (for example, the first PCF and the second PCF are the same, and the first PCF does not receive the second message from the first IMS network element and / or the third message from the second IMS network element. For another example, the first PCF and the second PCF are different, the first PCF can receive the second message from the first IMS network element, but cannot receive the third message from the second IMS network element; similarly, the second PCF can receive the third message from the second IMS network element, but cannot receive the second message from the first IMS network element), or the first PCF does not receive the second message and / or the third message from the first IMS network element (for example, the first PCF and the second PCF are the same, and the first IMS network element and the second IMS network element are the same IMS network element). It can be understood that if the first PCF receives the second message and the third message, indicating that the first IMS network element and the second IMS network element both determine that the first UE and the second UE exchange call data on the satellite, then if the first PCF also determines that the second condition is met, the first PCF can execute S810.

[0354] Alternatively, if the first PCF does not determine the second condition, then the first PCF may, if it receives the second message from the first IMS network element and the third message from the second IMS network element (or, if the first IMS network element and the second IMS network element are the same IMS network element, the first PCF may receive the second message and the third message from the IMS network element), deem that the first UE and the second UE can exchange call data over the satellite, and the first PCF may execute S810. Alternatively, if one or more of the following conditions are met, the first PCF deems that the first UE and the second UE cannot exchange call data over the satellite, and the first PCF may not execute S810: the first PCF does not receive the second message from the first IMS network element and / or the third message from the second IMS network element, or the first PCF does not receive the second message and / or the third message from the first IMS network element (wherein the first IMS network element and the second IMS network element are the same IMS network element).

[0355] As described above, the first PCF determines whether only one of the second and third messages has been received. For example, if the first PCF receives one of the second and third messages, it may start a timer. If the other of the second and third messages is received within the timer, it is determined that the second and third messages have been received, and the timer may be stopped. If the other of the second and third messages has not been received when the timer expires, it is determined that the other message has not been received.

[0356] If the first PCF believes that the first UE and the second UE cannot exchange call data on the satellite, the first PCF may optionally send a first rejection message to the first IMS network element. The first rejection message may indicate that the first UE and the second UE are rejected from exchanging call data on the satellite, or indicate that the first UE and the second UE are not allowed or supported to exchange call data on the satellite, or indicate that the first UE and the second UE cannot be configured to exchange call data on the satellite, or indicate that the configuration of exchanging call data on the satellite between the first UE and the second UE has failed, etc.

[0357] S811: The first PCF sends sixth information to the second SMF. Correspondingly, the second SMF receives the sixth information.

[0358] If the first SMF and the second SMF are the same SMF, the first PCF can send the fifth and sixth information to the SMF, and the SMF can receive the fifth and sixth information. Alternatively, the first PCF only needs to send the fifth information to the SMF without sending the sixth information, and the SMF can receive the fifth information. If the first SMF and the second SMF are different SMFs, the first PCF can send the sixth information to the second SMF in addition to the fifth information to the first SMF. Figure 8 uses the example of the first and second SMFs being different SMFs. The conditions required for the first PCF to send the sixth information are similar to those required to send the fifth information, and will not be elaborated on here.

[0359] Both the fifth information and the sixth information may indicate that the first UE and the second UE are exchanging call data over the satellite. For example, the fifth information may include the identifier of the first UE, the identifier of the second UE, and indication information C; the sixth information may include the identifier of the first UE, the identifier of the second UE, and indication information C. The indication information C may indicate that the first UE and the second UE are exchanging call data over the satellite. Optionally, the fifth information may be included in the first PCC rule, and the sixth information may be included in the second PCC rule.

[0360] Next, the SMF can configure the user plane of the IMS PDU session, that is, configure the UPF. For example, the SMF can configure the UPF on the satellite for the IMS PDU session of the first UE and the second UE based on the third condition, and configure the routing forwarding rules of the call data between the first UE and the second UE to be forwarded through the UPF on the satellite. The UPF is, for example, an uplink classifier (UL) UPF, a branching point (BP) UPF, or a local PDU session anchor (LPSA) UPF, thereby enabling the call data of the first UE and the second UE to be exchanged on the satellite without passing through the ground network. The configuration process may include the following S812 to S815. Wherein, if the first SMF and the second SMF are different SMFs, the SMF described above may include the first SMF and the second SMF, and the two SMFs may respectively perform configuration processes, for example, the first SMF configures the first UPF, and the second SMF configures the second UPF, thereby creating a transmission channel between the first UPF and the second UPF through the interaction between the first SMF and the second SMF; or, if the first SMF and the second SMF are the same, the SMF described above may include the SMF, and the SMF may configure the first UPF and the second UPF. Wherein, the first UPF and the second UPF may be the same UPF, or different UPFs.

[0361] S812: The first SMF sends third configuration information to the first UPF based on the third condition. In response, the first UPF receives the third configuration information. The third configuration information may configure the first UPF to directly forward call data between the first UE and the second UE.

[0362] Optionally, the third condition may include one or more of the following: the first UE and the second UE both access the network via satellite; or, the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, the first UE and the second UE are served by different UPFs, and the different UPFs are all deployed on the satellite, and data transmission channels can be established between the different UPFs; or, the first UE and the second UE are located on the same satellite; or, the first UE and the second UE are located on different satellites, and there is an inter-satellite link between the different satellites.

[0363] For example, a UPF can be deployed on a satellite, or a satellite has the function of a UPF. If the first UE and the second UE are located under the same satellite, it can be considered that the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite.

[0364] If the first UE and the second UE are located under different satellites, it indicates that the first UE and the second UE are served by different UPFs, and the different UPFs are both located on the satellites. If there is an inter-satellite link between the different satellites, it can indicate that a data transmission channel can be established between the different UPFs.

[0365] If the first UE and the second UE are served by the same UPF, and that UPF is deployed on a satellite, this indicates that call data between the first UE and the second UE can be exchanged on the satellite. Alternatively, if the first UE and the second UE are served by different UPFs, and those different UPFs can communicate or establish a data transmission channel, this indicates that call data between the first UE and the second UE can be exchanged locally via the UPFs. If both different UPFs are deployed on a satellite, call data between the first UE and the second UE can be exchanged on the satellite. Therefore, based on the third condition, the first SMF can determine whether the first UE and the second UE can exchange call data on the satellite.

[0366] For example, if the third condition is met, it indicates that the first UE and the second UE can exchange call data on the satellite, and the first SMF can send the third configuration information to the first UPF; if the third condition is not met, it indicates that the first UE and the second UE are not allowed to exchange call data on the satellite, and the first SMF may not send the third configuration information to the first UPF.

[0367] Optionally, if the third condition is not met, for example, if the first SMF determines that the first UE and the second UE cannot exchange call data over the satellite, the first SMF may optionally send eighth information to the first PCF, and the first PCF may receive the eighth information. For this, see S813. The eighth information may indicate the configuration result of the first SMF for the first UE and the second UE to exchange call data over the satellite. For example, if the first UE and the second UE cannot exchange call data over the satellite, the configuration result indicated by the eighth information may be unsupported configuration, unconfigurable configuration, or configuration failure.

[0368] Or, optionally, after executing S812, the first SMF may also execute S813. The configuration result indicated by the eighth information at this time may be configuration supported, configuration capable, configuration successful, or configured, etc.

[0369] If the first SMF and the second SMF are different SMFs, the first SMF may further receive configuration information A from the second SMF before sending the third configuration information, and the first SMF may obtain the third configuration information based on the configuration information determined by the first SMF and the configuration information A. For example, the first SMF may determine the third configuration information based on the configuration information of the first UPF by the first SMF and the configuration information of the first UPF by the second SMF.

[0370] The first SMF may send a request message to the second SMF to request configuration information A. Optionally, the request message may include configuration information B, which may be used by the second SMF to configure the second UPF. For example, if the configuration information B includes the configuration information of the first SMF for the second UPF, the second SMF may determine information for configuring the second UPF, such as the fourth configuration information, based on the configuration information of the second SMF for the second UPF and the configuration information B.

[0371] Alternatively, the first SMF may also receive configuration information A from the second SMF without request. Optionally, the configuration information A may also request the first SMF to provide configuration information for the second UPF. The first SMF may then send configuration information B to the second SMF, and the second SMF may determine the fourth configuration information based on the configuration information for the second UPF provided by the second SMF and the configuration information B.

[0372] S814: The second SMF sends fourth configuration information to the second UPF based on the third condition. Accordingly, the second UPF receives the fourth configuration information. The fourth configuration information may configure the second UPF to directly forward call data between the first UE and the second UE.

[0373] The second SMF may also perform similar processing as the first SMF, so for more details about S814, please refer to S812.

[0374] For example, if the third condition is met, it indicates that the first UE and the second UE can exchange call data on the satellite, and the second SMF can send the fourth configuration information to the second UPF; if the third condition is not met, it indicates that the first UE and the second UE are not allowed to exchange call data on the satellite, and the second SMF may not send the fourth configuration information to the second UPF.

[0375] Optionally, if the third condition is not met, for example, if the second SMF determines that the first UE and the second UE cannot exchange call data on the satellite, then optionally, the second SMF may send ninth information to the second PCF, and the second PCF may receive the ninth information. For this, reference may be made to S815. In this embodiment of the present application, the first PCF and the second PCF are the same PCF. The ninth information may indicate the configuration result of the second SMF for the first UE and the second UE to exchange call data on the satellite. For example, if the first UE and the second UE cannot exchange call data on the satellite, the configuration result indicated by the ninth information may be that the configuration is not supported, cannot be configured, or the configuration fails.

[0376] Or, optionally, after executing S814, the second SMF may also execute S815. The configuration result indicated by the ninth information at this time may be configuration supported, configuration capable, configuration successful, or configured, etc.

[0377] If the first SMF and the second SMF are different SMFs, the second SMF may further receive configuration information B from the first SMF before sending the fourth configuration information. The second SMF may obtain the fourth configuration information based on the configuration information determined by the second SMF and the configuration information B. For example, the second SMF may determine the fourth configuration information based on the configuration information of the second UPF by the second SMF and the configuration information of the second UPF by the first SMF. For more information on this, please refer to S812.

[0378] The foregoing text uses the example of a case where the first SMF and the second SMF are different SMFs. Alternatively, if the first SMF and the second SMF are the same SMF, the SMF may send the third configuration information to the first UPF and the fourth configuration information to the second UPF. In addition, the SMF may also send the eighth configuration information to the first PCF. In addition, if the first UPF and the second UPF are the same UPF, the first SMF may send the third configuration information to the UPF, and the second SMF may send the fourth configuration information to the UPF. Alternatively, if the first UPF and the second UPF are the same UPF and the first SMF and the second SMF are the same SMF, the SMF may send the third configuration information to the UPF.

[0379] S816: The first PCF sends the seventh information to the first IMS network element. Correspondingly, the first IMS network element receives the seventh information.

[0380] The seventh information may indicate a configuration result for the first UE and the second UE to exchange call data on the satellite.

[0381] Optionally, if the first SMF and the second SMF are the same SMF, the first PCF may send the seventh information to the first IMS network element after receiving the eighth information. Alternatively, if the first SMF and the second SMF are different SMFs, the first PCF may optionally send the seventh information to the first IMS network element after receiving the eighth information and the ninth information. If the first IMS network element and the second IMS network element are different IMS network elements, then after receiving the eighth information (or after receiving the eighth information and the ninth information), in addition to sending the seventh information to the first IMS network element, the first PCF may also send the seventh information to the second IMS network element. For this, refer to S817. The seventh information may indicate a configuration result for exchanging call data between the first UE and the second UE on the satellite.

[0382] For example, if the configuration result indicated by the eighth information is that configuration is supported or can be configured or configuration is successful or has been configured, etc., and the configuration result indicated by the ninth information is that configuration is supported or can be configured or configuration is successful or has been configured, etc., then the configuration result indicated by the seventh information may be that configuration is supported or can be configured or configuration is successful or has been configured, etc.; or, if the configuration result indicated by the eighth information is that configuration is not supported or cannot be configured or configuration fails, etc., and / or the configuration result indicated by the ninth information is that configuration is not supported or cannot be configured or configuration fails, etc., then the configuration result indicated by the seventh information may be that configuration is not supported or cannot be configured or configuration fails, etc.

[0383] Optionally, the method may further include S819, completing IMS session establishment or completing call establishment. After S819, the first UE and the second UE may start a call. S819 may include other related steps for establishing a call, which will not be described in detail in this embodiment of the application.

[0384] The UPF in the embodiment of the present application can locally exchange call data between the first UE and the second UE. Both the first UE and the second UE access the network through a satellite. For example, the UPF can exchange call data between the first UE and the second UE on the satellite. As a result, call data can be exchanged on the satellite without being routed to the ground network, shortening the transmission path of the call data and reducing latency. Since the UPF can perform local exchange of call data between devices, the call data can directly reach the call counterpart device from the UPF without having to pass through the transmission of network elements such as the IMS network element, thereby further shortening the transmission path and further reducing latency. In addition, network elements such as the IMS network element, PCF, and SMF can all make corresponding judgments on whether the first UE and the second UE can exchange call data on the satellite, so that the first UE and the second UE can exchange call data on the satellite if the conditions are met, which meets the requirements of communication scenarios and various communication parameters.

[0385] In the embodiment shown in FIG8 , it is described that the first IMS network element and the second IMS network element can be the same network element or different network elements. FIG8 mainly describes the case where the first IMS network element and the second IMS network element are the same network element, and describes the processing steps of the first IMS network element when the first IMS network element and the second IMS network element are different network elements. However, if the first IMS network element and the second IMS network element are different network elements, the second IMS network element can also perform similar processing as the first IMS network element.

[0386] In the embodiment shown in FIG8 , if the first IMS network element and the second IMS network element are different network elements, the first IMS network element may not be able to obtain information about the second UE when determining whether the first condition is satisfied, and the second IMS network element may also be unable to obtain information about the first UE when determining whether the first condition is satisfied. The following describes another communication method provided in an embodiment of the present application. By using this method, the first IMS network element can obtain information about the second UE, and the second IMS network element can obtain information about the first UE, thereby enabling the IMS network elements to perform more determination processes, resulting in more accurate determination results.

[0387] Please refer to Figure 9, which is a flowchart of the method. In the embodiment of the present application, the first IMS network element and the second IMS network element are different IMS network elements. The embodiment shown in Figure 9 can be included in the embodiment shown in Figure 8. For example, it is an improvement of some steps in the embodiment shown in Figure 8. Therefore, other steps other than the aforementioned steps are not described in detail in the embodiment shown in Figure 9. Reference may be made to the embodiment shown in Figure 8. For example, S901 described below may be the same step as S806 in the embodiment shown in Figure 8, and S903 described below may be the same step as S808 in the embodiment shown in Figure 8.

[0388] S901. A first IMS network element determines, based on a first condition, whether to allow a first UE and a second UE to exchange call data over a satellite. Alternatively, the first IMS network element determines whether the second UE meets a condition for exchanging call data over a satellite, for example, the condition is referred to as the first condition.

[0389] Optionally, the first IMS network element determines that the first UE and the second UE exchange call data on the satellite, which may include one or more of the following, or the first IMS network element may determine that the first UE and the second UE exchange call data on the satellite by one or more of the following: determining that the network allows the first UE to exchange call data on the satellite; or, determining that the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, determining that the first UE and the second UE are served by the same IMS network element; or, determining that the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, determining The method comprises the following steps: matching media description information supported by a UE and a second UE; determining that a serving PLMN of the first UE and a serving PLMN of the second UE are the same PLMN; determining that lawful interception is not performed on a call between the first UE and the second UE; determining that the first UE and the second UE are located on the same satellite; determining that the first UE and the second UE are located on different satellites and that there is an inter-satellite link between the different satellites; determining that when the first UE is in a roaming state, the first UE does not perform home routing in the call; determining that the first UE and the second UE are served by the same PCF; determining that an IMS PDU session of the first UE and an IMS PDU session of the second UE are served by the same PCF; determining that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same SMF; determining that the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF and by the same SMF; determining that the network allows the second UE to exchange call data on the satellite; or determining that when the second UE is in a roaming state, the second UE does not perform home routing in the call.

[0390] Alternatively, the first condition may include one or more of the following: the network allows the first UE to exchange call data on the satellite; or, the first UE and the second UE are served by the same UPF, which is deployed on the satellite; or, the first UE and the second UE are served by the same IMS network element; or, the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, the media description information supported by the first UE and the second UE matches; or, the service PLMN of the first UE and the service PLMN of the second UE are the same PLMN; or, no legal interception is performed on the call between the first UE and the second UE; or, the first UE and the second UE are located under the same satellite; or, the first UE and the second UE are located under different satellites, and there is an inter-satellite link between the different satellites; or, when the first UE is in roaming state, the first UE does not perform home routing in the call; or, the first UE and the second UE are served by the same PCF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same PCF; or, the IMS PDU session of the first UE and the IMS PDU session of the second UE are served by the same SMF; or, the IMS The PDU session and the IMS PDU session of the second UE are served by the same PCF and the same SMF; or, the network allows the second UE to exchange call data on the satellite; or, when the second UE is in a roaming state, the second UE does not perform home routing in the call.

[0391] In the embodiment of the present application, the first IMS network element and the second IMS network element are different network elements, but the two IMS network elements can interact to obtain relevant information of the opposite UE, thereby performing the determination of the first condition.

[0392] As an optional implementation, the first IMS network element may send information D to the second IMS network element. For this, see S902. Information D may include one or more of the following: information about the first PCF, information about the first SMF, an identifier of a satellite serving the first UE, information about the serving PLMN of the first UE, an identifier of a serving cell of the first UE, or indication information. This indication information, for example, is referred to as indication information A, which may instruct the first UE and the second UE to exchange call data over the satellite.

[0393] For example, the first IMS network element may send the information D to the second IMS network element after determining, based on the first condition, that the first UE and the second UE can exchange call data over the satellite. Alternatively, the first IMS network element may send the information D to the second IMS network element upon determining that the first UE accesses the network via the satellite and / or upon determining that the first UE is permitted to exchange call data over the satellite. Therefore, if the first IMS network element sends the information D, it can indicate that the first IMS network element permits the first UE and the second UE to exchange call data over the satellite. For the second IMS network element, if it receives the information D from the first IMS network element, it can determine that the first IMS network element permits the first UE and the second UE to exchange call data over the satellite; if it does not receive the information D, it can determine that the first IMS network element does not permit the first UE and the second UE to exchange call data over the satellite.

[0394] After receiving the information D from the first IMS network element, the second IMS network element may determine whether the first condition is met, or whether the first UE and the second UE are permitted to exchange call data over the satellite. For this, see S903. For example, if the first condition is met, the second IMS network element may send a confirmation message to the first IMS network element. For this, see S904. Alternatively, if the first condition is not met, the second IMS network element may send an indication message B to the first IMS network element. For this, see S905. Optionally, if the first condition is met, or if it is determined whether the first UE and the second UE are permitted to exchange call data over the satellite, the second IMS network element may also execute S809 in the embodiment shown in FIG. 8 .

[0395] Furthermore, for the first IMS network element, if the confirmation information in S904 is received, S807 in the embodiment shown in Figure 8 may be executed. Thus, if the first IMS network element and the second IMS network element are different network elements, the first IMS network element may execute S807 if, based on the first condition, it determines that the first UE and the second UE are permitted to exchange call data over the satellite, and if it receives confirmation information from the second IMS network element. If, based on the first condition, the first IMS network element determines that the first UE and the second UE are not permitted to exchange call data over the satellite, and / or if it does not receive confirmation information from the second IMS network element, S807 may not be executed. In this case, it can also be considered that, for the first IMS network element, the first condition may also include receiving confirmation information from the second IMS network element.

[0396] Among them, the confirmation information can be used to confirm or instruct the first UE and the second UE to exchange call data on the satellite; the indication information B can be used to reject the first UE and the second UE from exchanging call data on the satellite, or indicate that the first UE and the second UE are not allowed or supported to exchange call data on the satellite.

[0397] Optionally, for the second IMS network element, the first condition may include one or more of the following: allowing the second UE to exchange call data on the satellite; or, the first UE and the second UE are served by the same UPF, and the UPF is deployed on the satellite; or, the first UE and the second UE are served by different UPFs, and the different UPFs are both deployed on the satellite; or, the first UE and the second UE are served by the same IMS network element; or, the media description information used by the first UE and the second UE matches; or, the service PLMN of the first UE is the same as the service PLMN of the second UE; or, the first UE and the second UE are located under the same satellite; or, the first UE and the second UE are located under different satellites, and there is an inter-satellite link between the different satellites; or, lawful interception of the call of the second UE is not performed; or, when the first UE is in roaming state, the first UE does not perform home routing in the call; or, the PCF serving the first UE is the same as the PCF serving the second UE; or, the PCF serving the IMS PDU session of the first UE is the same as the PCF serving the IMS PDU session of the second UE; or, the SMF serving the IMS PDU session of the first UE is the same as the IMS serving the second UE. The SMF of the IMS PDU session serving the first UE is the same as that of the IMS PDU session serving the second UE; or, the SMF of the IMS PDU session serving the first UE is the same as the PCF and the SMF of the IMS PDU session serving the second UE. It can be seen that the content included in the fourth condition is similar to that included in the first condition, for example, the fourth condition is the same as the first condition.

[0398] For example, the information D sent by the first IMS network element to the second IMS network element includes the information of the first PCF and the indication information A. After receiving the indication information A and the information of the first PCF, the second IMS network element can determine whether the first PCF and the second PCF are the same PCF (wherein, the second IMS network element can first obtain the information of the second PCF, and the acquisition method can refer to the method in which the first IMS network element obtains the information of the first PCF). If the first PCF and the second PCF are the same PCF, the second IMS network element can send a confirmation message to the first IMS network element; or, if the first PCF and the second PCF are different PCFs, the second IMS network element can send an indication message B to the first IMS network element.

[0399] For another example, the information D sent by the first IMS network element to the second IMS network element includes the information of the first PCF, the information of the first SMF, and the indication information A. After receiving the indication information A, the information of the first SMF, and the information of the first PCF, the second IMS network element can determine whether the first PCF and the second PCF are the same PCF, and determine whether the first SMF and the second SMF are the same SMF (wherein, the second IMS network element can first obtain the information of the second PCF and the information of the second SMF, and the acquisition method can refer to the method in which the first IMS network element obtains the information of the first PCF and the information of the first SMF). If the first PCF and the second PCF are the same PCF, and the first SMF and the second SMF are the same SMF, the second IMS network element can send a confirmation message to the first IMS network element; or, if the first PCF and the second PCF are different PCFs, and / or the first SMF and the second SMF are different SMFs, the second IMS network element can send an indication message B to the first IMS network element.

[0400] For another example, the information D sent by the first IMS network element to the second IMS network element includes the identifier of the satellite serving the first UE. After receiving the information D, the second IMS network element can determine the identifier of the satellite serving the second UE. For example, if the identifier of the satellite serving the first UE and the identifier of the satellite serving the second UE are the same, indicating that the two UEs are served by the same satellite, the second IMS network element can send a confirmation message to the first IMS network element. Alternatively, if the identifier of the satellite serving the first UE and the identifier of the satellite serving the second UE are different, indicating that the two UEs are served by different satellites, the second IMS network element can send an indication message B to the first IMS network element. Alternatively, if the identifier of the satellite serving the first UE and the identifier of the satellite serving the second UE are different, but there is an inter-satellite link between the two satellites, the second IMS network element can send a confirmation message to the first IMS network element. Alternatively, if the identifier of the satellite serving the first UE and the identifier of the satellite serving the second UE are different, and there is no inter-satellite link between the two satellites, the second IMS network element can send an indication message B to the first IMS network element.

[0401] For another example, the first IMS network element sends information D to the second IMS network element, including information about the serving PLMN of the first UE. After receiving information D, the second IMS network element can determine the serving PLMN of the second UE. For example, if the serving PLMN of the first UE and the serving PLMN of the second UE are the same, the second IMS network element can send a confirmation message to the first IMS network element; alternatively, if the serving PLMN of the first UE and the serving PLMN of the second UE are different, the second IMS network element can send an indication message B to the first IMS network element.

[0402] For another example, the information D sent by the first IMS network element to the second IMS network element includes the identifier of the serving cell of the first UE. After receiving the information D, the second IMS network element can determine the identifier of the serving cell of the second UE. For example, if the identifier of the serving cell of the first UE and the identifier of the serving cell of the second UE are the same, the second IMS network element can send a confirmation message to the first IMS network element; or, if the identifier of the serving cell of the first UE and the identifier of the serving cell of the second UE are different, the second IMS network element can send an indication message B to the first IMS network element.

[0403] Among them, if the information D includes multiple parameters, the second IMS network element needs to determine these multiple parameters separately, and will only send a confirmation message if these multiple parameters all meet the conditions. If any one or more of these multiple parameters do not meet the conditions, the second IMS network element can send an indication message B. For example, the information D sent by the first IMS network element to the second IMS network element includes the information of the service PLMN of the first UE and the information of the first PCF. After receiving the information D, the second IMS network element can determine the information of the service PLMN of the second UE, and determine whether the first PCF and the second PCF are the same PCF. For example, if the service PLMN of the first UE and the service PLMN of the second UE are the same, and the first PCF and the second PCF are the same PCF, the second IMS network element can send a confirmation message to the first IMS network element; or, if the service PLMN of the first UE and the service PLMN of the second UE are different, and / or the first PCF and the second PCF are different PCFs, the second IMS network element can send an indication message B to the first IMS network element.

[0404] If the first IMS network element receives confirmation information from the second IMS network element, it can be determined that the first UE and the second UE can exchange call data on the satellite; if the first IMS network element receives indication information B from the second IMS network element or does not receive confirmation information, it can be determined that the first UE and the second UE are not allowed to exchange call data on the satellite.

[0405] For more details about S901 and S903, such as related information about the first condition, please refer to S806 and / or S808 of the embodiment shown in Figure 8. Other steps involved in the embodiment of the present application will not be described in detail, and please refer to the relevant introduction of the embodiment shown in Figure 8.

[0406] The UPF in the embodiments of the present application can locally exchange call data between a first UE and a second UE. Both the first UE and the second UE access the network via a satellite. For example, the UPF can exchange call data between the first UE and the second UE on the satellite. Thus, call data can be exchanged on the satellite without having to be routed to the terrestrial network, shortening the call data transmission path and reducing latency. Because the UPF can perform local exchange of call data between devices, the call data can directly reach the other end device from the UPF without having to be transmitted through network elements such as IMS network elements, further shortening the transmission path and reducing latency. In addition, network elements such as IMS network elements, PCF, and SMF can all perform corresponding judgments on whether the first UE and the second UE can exchange call data on the satellite. This allows the first UE and the second UE to exchange call data on the satellite if the conditions are met, meeting the requirements of communication scenarios and various communication parameters. Moreover, in the embodiments of the present application, different IMS network elements can exchange information, allowing the IMS network elements to obtain more information to perform more judgment processes, which helps to improve the accuracy of the judgment results.

[0407] FIG6 shows a schematic diagram of the structure of a communication device provided in an embodiment of the present application. The communication device 600 may be the first UE or the circuit system of the first UE as described in the embodiment shown in any one of FIG. 4A , FIG. 4B , or FIG. 5A , for implementing the method corresponding to the first UE in the above method embodiment. Alternatively, the communication device 600 may be the second UE or the circuit system of the second UE as described in the embodiment shown in any one of FIG. 4A , FIG. 4B , FIG. 5A , FIG. 8 , or FIG. 9 , for implementing the method corresponding to the second UE in the above method embodiment. Alternatively, the communication device 600 may be the IMS network element or the circuit system of the IMS network element as described in the embodiment shown in any one of FIG. 4A , FIG. 4B , FIG. 5A , FIG. 8 , or FIG. 9 , for implementing the method corresponding to the IMS network element in the above method embodiment. Alternatively, the communication device 600 may be the SMF or the circuit system of the SMF as described in the embodiment shown in any one of FIG. 4A , FIG. 4B , FIG. 5A , FIG. 8 , or FIG. 9 , for implementing the method corresponding to the SMF in the above method embodiment. Alternatively, the communication device 600 may be the UPF or the circuit system of the UPF as described in any of the embodiments shown in Figures 4A, 4B, 5A, 8, or 9, for implementing the method corresponding to the UPF in the above method embodiments. Alternatively, the communication device 600 may be the PCF or the circuit system of the PCF as described in any of the embodiments shown in Figures 4A, 4B, 5A, 8, or 9, for implementing the method corresponding to the PCF in the above method embodiments. For example, one circuit system is a chip system.

[0408] The communication device 600 includes at least one processor 601. Processor 601 can be used for internal processing of the device, implementing certain control processing functions. Optionally, processor 601 includes instructions. Optionally, processor 601 can store data. Optionally, different processors can be independent devices, located in different physical locations, or on different integrated circuits. Optionally, different processors can be integrated into one or more processors, for example, on one or more integrated circuits.

[0409] Optionally, the communication device 600 includes one or more memories 603 for storing instructions. Optionally, data may also be stored in the memories 603. The processor and memory may be provided separately or integrated together.

[0410] Optionally, the communication device 600 includes a communication line 602 and at least one communication interface 604. Since the memory 603, the communication line 602 and the communication interface 604 are all optional, they are indicated by dotted lines in FIG6 .

[0411] Optionally, the communication device 600 may further include a transceiver and / or an antenna. The transceiver may be used to send information to or receive information from other devices. The transceiver may be referred to as a transceiver, a transceiver circuit, an input / output interface, etc., and is used to implement the transceiver function of the communication device 600 via an antenna. Optionally, the transceiver includes a transmitter and a receiver. For example, the transmitter may be used to generate a radio frequency signal from a baseband signal, and the receiver may be used to convert the radio frequency signal into a baseband signal.

[0412] The processor 601 may include a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program of the present application.

[0413] Communication link 602 may include a pathway for transmitting information between the aforementioned components.

[0414] The communication interface 604 uses any transceiver or other device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area network (WLAN), wired access network, etc.

[0415] The memory 603 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including a compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 603 may exist independently and be connected to the processor 601 via the communication line 602. Alternatively, the memory 603 may be integrated with the processor 601.

[0416] The memory 603 is used to store computer-executable instructions for executing the solution of the present application, and the execution is controlled by the processor 601. The processor 601 is used to execute the computer-executable instructions stored in the memory 603, thereby implementing the steps performed by the first UE or the second UE or the IMS network element or the SMF or the UPF or the PCF in the embodiment shown in any one of Figures 4A, 4B, 5A, 8, or 9.

[0417] Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application code, which is not specifically limited in the embodiments of the present application.

[0418] In a specific implementation, as an embodiment, the processor 601 may include one or more CPUs, such as CPU0 and CPU1 in FIG6 .

[0419] In a specific implementation, as an embodiment, the communication device 600 may include multiple processors, such as processor 601 and processor 605 in FIG6 . Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0420] When the device shown in FIG6 is a chip, for example, a chip of a first UE, a chip of a second UE, a chip of an IMS network element, a chip of an SMF, a chip of a UPF, or a chip of a PCF, the chip includes a processor 601 (and may also include a processor 605), a communication circuit 602, and a communication interface 604. Optionally, the chip may include a memory 603. Specifically, the communication interface 604 may be an input interface, a pin, or a circuit. The memory 603 may be a register, a cache, or the like. The processor 601 and the processor 605 may be a general-purpose CPU, a microprocessor, an ASIC, or one or more integrated circuits for controlling the execution of the program of the communication method of any of the above embodiments.

[0421] In the embodiment of the present application, the functional modules of the device can be divided according to the above method examples. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation. For example, in the case of dividing each functional module according to each function, Figure 7 shows a schematic diagram of a device. The device 700 can be the first UE or the second UE or the IMS network element or the SMF or the UPF or the PCF involved in the above method embodiments, or a chip in the first UE or the chip in the second UE or the chip in the SMF or the chip in the IMS network element or the chip in the UPF or the chip in the PCF. The device 700 includes a processing unit 702 and a transceiver unit 701.

[0422] It should be understood that the device 700 can be used to implement the steps performed by the first UE or the second UE or the IMS network element or the SMF or the UPF or the PCF in the communication method of the embodiment of the present application. The relevant features can refer to the embodiments shown in any of Figures 4A, 4B, 5A, 8 or 9 above, and will not be repeated here.

[0423] Optionally, the functions / implementation processes of the transceiver unit 701 and the processing unit 702 in FIG7 may be implemented by the processor 601 in FIG6 calling computer-executable instructions stored in the memory 603. Alternatively, the functions / implementation processes of the processing unit 702 in FIG7 may be implemented by the processor 601 in FIG6 calling computer-executable instructions stored in the memory 603, and the functions / implementation processes of the transceiver unit 701 in FIG7 may be implemented by the communication interface 604 in FIG6.

[0424] Optionally, when the device 700 is a chip or circuit, the functions / implementation processes of the transceiver unit 701 may also be implemented via pins or circuits. Optionally, the transceiver unit 701 may include a transmitting unit and / or a receiving unit, where the transmitting unit is configured to implement the transmitting function and the receiving unit is configured to implement the receiving function. Alternatively, the transceiver unit 701 may be an integral module capable of implementing the transmitting function and / or the receiving function. Optionally, the transceiver unit 701 may be implemented via a transceiver.

[0425] The present application also provides a computer-readable storage medium, which stores a computer program or instruction. When the computer program or instruction is executed, the method performed by the first UE or the second UE or the SMF or the UPF or the IMS network element or the PCF in the above-mentioned method embodiment is implemented. In this way, the functions described in the above embodiments can be implemented in the form of software functional units and sold or used as independent products. Based on this understanding, the technical solution of the present application can be essentially or in other words, the part that contributes to or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0426] The present application also provides a computer program product, which includes: computer program code, which, when running on a computer, enables the computer to execute the method performed by the first UE or the second UE or the SMF or the UPF or the IMS network element or the PCF in any of the aforementioned method embodiments.

[0427] An embodiment of the present application also provides a processing device, including a processor and an interface; the processor is used to execute the method executed by the first UE or second UE or SMF or UPF or IMS network element or PCF involved in any of the above method embodiments.

[0428] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0429] The various illustrative logic units and circuits described in the embodiments of the present application can be implemented or operated by a general-purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor, and optionally, the general-purpose processor can also be any conventional processor, controller, microcontroller or state machine. The processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other similar configuration.

[0430] The steps of the methods or algorithms ...

Claims

1. A communication method, characterized in that: The method comprises: Receiving first information from an Internet Protocol Multimedia Subsystem (IMS) network element, wherein the first information is used to instruct the first device and the second device to perform a call; According to the first information, first configuration information is sent to the user plane function UPF, wherein the first configuration information is used to configure the UPF to perform local switching of call data between the first device and the second device, wherein both the first device and the second device access the network via a satellite.

2. The method according to claim 1, characterized in that The UPF is located on the satellite.

3. The method according to claim 1 or 2, characterized in that: The method further comprises: In a case where the first information is also used to indicate that the first device and the second device exchange call data on a satellite, determining, according to the first information, that the first device and the second device exchange call data on a satellite; or, According to the UPF serving the first device and the second device, it is determined that the first device and the second device exchange call data on the satellite.

4. The method according to claim 3, characterized in that Determining, according to the UPF serving the first device and the second device, that the first device and the second device exchange call data on a satellite includes: Determining that the first device and the second device are served by the same UPF; or, Determine that the first device and the second device are served by different UPFs, wherein the different UPFs support establishing data transmission channels.

5. The method according to any one of claims 1 to 4, characterized in that: The first information also includes one or more of the following: a first identifier of the first device; a second identifier of the first device; address information of the first device; a first identifier of the second device; a second identifier of the second device; address information of the second device; Caller information; Called information, or Description information of the call data.

6. A communication method, characterized in that: The method comprises: receiving a first request from a first device, wherein the first request is for requesting a call with a second device; Sending first information to a first core network element, wherein the first information is used to instruct the first device and the second device to perform a call, wherein the first information is also used to instruct the first device and the second device to exchange call data on a satellite.

7. The method according to claim 6, characterized in that The method further comprises: It is determined that the first device and the second device exchange call data on a satellite.

8. The method according to claim 7, characterized in that Determining that the first device and the second device exchange call data on the satellite includes one or more of the following: Determining that the first device and the second device are served by the same UPF, and the UPF is located on a satellite; Determining that the first device and the second device are served by the same IMS network element; determining that the first device and the second device are served by different UPFs, wherein the different UPFs are both located on a satellite; or, It is determined that media description information of the first device matches that of the second device.

9. The method according to claim 8, characterized in that Determining that the first device and the second device are served by the same IMS network element includes: According to the second identifier of the second device carried in the first request, it is determined that the first device and the second device are served by the same IMS network element, and the IMS network element uniquely corresponds to one UPF.

10. The method according to claim 9, characterized in that Determining, according to the second identifier of the second device carried in the first request, that the first device and the second device are served by the same IMS network element includes: According to the second identifier of the second device and the second identifier of the first device, it is determined that both the first device and the second device perform IMS registration through the same IMS network element.

11. The method according to claim 9 or 10, characterized in that: The second identifier of the second device includes a uniform resource locator and / or a uniform resource identifier of the second device.

12. The method according to claim 8, characterized in that Determining that the first device and the second device are served by the same UPF includes: Determine that the first request and the request from the second device come from the same UPF.

13. The method according to any one of claims 6 to 12, characterized in that: Determining that the first device and the second device exchange call data on a satellite includes: When the call between the first device and the second device corresponds to a delay processing strategy, determining that the first device and the second device exchange call data on a satellite; and / or, When the disaster recovery strategy is executed, it is determined that the first device and the second device exchange call data on the satellite.

14. The method according to any one of claims 6 to 13, characterized in that: The method further comprises: Determining, based on the subscription information of the first device, that the network allows the call data of the first device to be exchanged on the satellite, and / or determining, based on the subscription information of the second device, that the network allows the call data of the second device to be exchanged on the satellite; or, receiving second information, wherein the second information is used to indicate that the first device requests that the call data of the first device be exchanged on a satellite, and / or indicates that the second device requests that the call data of the second device be exchanged on a satellite; or, Third information is received, wherein the third information is used to indicate that a network allows the call data of the first device to be exchanged on a satellite, and / or indicates that the network allows the call data of the second device to be exchanged on a satellite.

15. The method according to any one of claims 6 to 14, characterized in that: The call data is not transmitted via IMS.

16. A communication method, characterized in that: The method comprises: receiving first configuration information; Local switching of call data between a first device and a second device is performed according to the first configuration information configuration, wherein both the first device and the second device access a network via a satellite.

17. The method according to claim 16, characterized in that The UPF is located on the satellite.

18. The method according to claim 16 or 17, characterized in that Configuring the local switching of call data between the first device and the second device according to the first configuration information includes one or more of the following: For call data from a communication device, setting a rule for filtering data to filter out call data between the first device and the second device, wherein the communication device is the first device or the second device; For call data from the communication device, setting a rule for forwarding data to forward to the UPF; For the call data received by the UPF and forwarded by the UPF, the destination address of the call data is set to the address information of the communication peer device, wherein if the call data comes from the first device, the communication peer device is the second device, or if the call data comes from the second device, the communication peer device is the first device; or, For the call data received by the UPF and forwarded by the UPF, a rule for forwarding the call data is set to forward the call data to a communication peer device.

19. A communication method, characterized in that: The method comprises: Receiving a first request from a first device, the first request being used to request a call with a second device, wherein both the first device and the second device access a network via a satellite; determining that the first device and the second device exchange call data on the satellite; The address information of the second device is sent to the first device, and the address information of the first device is sent to the second device.

20. The method according to claim 19, characterized in that The method further comprises: A registration request is received from a communication device, wherein a message header of the registration request includes address information of the communication device, and the communication device includes the first device or the second device.

21. The method according to claim 19 or 20, characterized in that Determining that the first device and the second device exchange call data on a satellite includes: Determining that the first device and the second device are served by the same UPF, wherein the UPF is located on a satellite; and / or, It is determined that the first device and the second device are served by the same IMS network element.

22. The method according to claim 21, characterized in that Determining that the first device and the second device exchange call data on a satellite further includes: It is determined that media description information of the first device matches that of the second device.

23. The method according to claim 21 or 22, characterized in that Determining that the first device and the second device are served by the same IMS network element includes: According to the second identifier of the second device carried in the first request, it is determined that the first device and the second device are served by the same IMS network element.

24. The method according to claim 23, characterized in that Determining, according to the second identifier of the second device carried in the first request, that the first device and the second device are served by the same IMS network element includes: According to the second identifier of the second device and the second identifier of the first device, it is determined that both the first device and the second device perform IMS registration through the same IMS network element.

25. The method according to claim 23 or 24, characterized in that The second identifier of the second device includes a uniform resource locator and / or a uniform resource identifier of the second device.

26. The method according to claim 21 or 22, characterized in that Determining that the first device and the second device are served by the same UPF includes: Determine that the first request and the request from the second device come from the same UPF.

27. The method according to any one of claims 19 to 26, characterized in that: Determining that the first device and the second device exchange call data on a satellite includes: When the call between the first device and the second device corresponds to a delay processing strategy, determining that the first device and the second device exchange call data on a satellite; and / or, When the disaster recovery strategy is executed, it is determined that the first device and the second device exchange call data on the satellite.

28. The method according to any one of claims 19 to 27, characterized in that: The method may further include one or more of the following: Determining, based on the subscription information of the first device, that the network allows the call data of the first device to be exchanged on the satellite, and / or determining, based on the subscription information of the second device, that the network allows the call data of the second device to be exchanged on the satellite; or, receiving second information, wherein the second information is used to indicate that the first device requests that the call data of the first device be exchanged on a satellite, and / or indicates that the second device requests that the call data of the second device be exchanged on a satellite; or, Third information is received, wherein the third information is used to indicate that a network allows the call data of the first device to be exchanged on a satellite, and / or indicates that the network allows the call data of the second device to be exchanged on a satellite.

29. The method according to any one of claims 19 to 28, characterized in that: The call data is not transmitted via IMS.

30. A communication method, characterized in that: Applied to a communication device, the method comprises: receiving a second request from an IMS network element, wherein the second request includes address information of a communication peer device, wherein the communication device is a calling device and the communication peer device is a called device, or the communication device is a called device and the communication peer device is a calling device, and both the communication device and the communication peer device access a network via a satellite; Send call data to UPF, the destination address information of the call data is the address information of the communication peer device.

31. The method according to claim 30, characterized in that The method further comprises: Sending second information to the IMS network element, where the second information is used to instruct the communication device to request that the call data of the communication device be exchanged on the satellite.

32. The method according to claim 30 or 31, characterized in that The method further comprises: A registration request is sent to the IMS network element, where the registration request is used to request registration with the IMS network element, wherein the registration request is also used to instruct the communication device to access a network via a satellite.

33. A communication method, characterized in that: The method comprises: receiving a first message, wherein the first message is used by the first device to request a call with the second device, or by the second device to respond to the call request from the first device; Based on a first condition, determining to allow the first device and the second device to exchange call data on the satellite; A second message is sent to a second core network element, where the second message includes an identifier of the first device, an identifier of the second device, and fourth information, where the fourth information is used to request the first device and the second device to exchange call data on a satellite. The second core network element is a second core network element that serves an IMS PDU session of the first device and / or serves the second device.

34. The method according to claim 33, characterized in that The first condition includes one or more of the following: allowing the first device and / or the second device to exchange call data on the satellite; The first device and the second device are served by a same user plane function entity, and the same user plane function entity is deployed on a satellite; The first device and the second device are served by the same IMS network element; The first device and the second device are served by different user plane function entities, and the different user plane function entities are deployed on a satellite; The media description information used by the first device and the second device matches; The serving PLMN of the first device is the same as the serving PLMN of the second device; The first device and the second device are located under the same satellite; The first device and the second device are located under different satellites, and there is an inter-satellite link between the different satellites; not conduct lawful interception of the call; When at least one of the first device or the second device accesses a roaming network, the device accessing the roaming network does not perform home routing in the call; The IMS PDU session of the first device and the IMS PDU session of the second device are served by the same second core network element; or, The IMS PDU session of the first device and the IMS PDU session of the second device are served by the same second core network element and the same first core network element.

35. The method according to claim 34, characterized in that The method further comprises: Acquire information of a second core network element serving the IMS PDU session of the first device, and / or acquire information of a second core network element serving the IMS PDU session of the second device; or, Obtain information about the second core network element and the first core network element that serve the IMS PDU session of the first device, and / or obtain information about the second core network element and the first core network element that serve the IMS PDU session of the second device.

36. The method according to claim 35, characterized in that The method further comprises: Sending at least one of the following to a second IMS network element serving the second device: Instruction information, where the instruction information is used to instruct the first device and the second device to exchange call data on the satellite; Information of a user plane functional entity serving the first device; Information of a serving PLMN of the first device; an identification of a satellite serving the first device; an identifier of a serving cell of the first device; Information of a second core network element serving the IMS PDU session of the first device; or, Information of the first core network element serving the IMS PDU session of the first device.

37. The method according to claim 36, characterized in that Sending at least one of the following to a second IMS network element serving the second device, including: When the first device accesses a network via a satellite and / or allows the first device to exchange call data on a satellite, at least one of the following items is sent to the second IMS.

38. The method according to claim 36 or 37, characterized in that The method further comprises: Receive confirmation information from the second IMS network element, where the confirmation information is used to confirm that the first device and the second device exchange call data on the satellite.

39. The method according to claim 35, characterized in that The method further comprises: Receiving at least one of the following from the first IMS network element: Instruction information, where the instruction information is used to instruct the first device and the second device to exchange call data on the satellite; Information of a user plane functional entity serving the first device; Information of a serving PLMN of the first device; an identification of a satellite serving the first device; The identifier of the serving cell of the first device Information of a second core network element serving the IMS PDU session of the first device; or, Information of the first core network element serving the IMS PDU session of the first device.

40. The method according to claim 39, characterized in that The method further comprises: Sending confirmation information to the first IMS network element, where the confirmation information is used to confirm that the first device and the second device exchange call data on the satellite.

41. The method according to claim 40, characterized in that Sending confirmation information to the first IMS network element includes: When at least one of the following conditions is met, sending the confirmation information to the first IMS network element: allowing the second device to exchange call data on the satellite; The first device and the second device are served by a same user plane function entity, and the same user plane function entity is deployed on a satellite; The first device and the second device are served by different user plane function entities, and the different user plane function entities are deployed on a satellite; The media description information used by the first device and the second device matches; The serving PLMN of the first device is the same as the serving PLMN of the second device; The first device and the second device are located under the same satellite; The first device and the second device are located under different satellites, and there is an inter-satellite link between the different satellites; not performing lawful interception on the call of the second device; The second core network element serving the IMS PDU session of the first device is the same as the second core network element serving the IMS PDU session of the second device; or, The second core network element serving the IMS PDU session of the first device is the same as the second core network element serving the IMS PDU session of the second device, and the first core network element serving the IMS PDU session of the first device is the same as the first core network element serving the IMS PDU session of the second device.

42. The method according to any one of claims 33 to 35, characterized in that: The method further comprises: Receive seventh information from the network element of the second core network, where the seventh information is used to indicate a configuration result for exchanging call data between the first device and the second device on a satellite.

43. The method according to any one of claims 33 to 42, characterized in that: The first device is a calling device of the call, and the second device is a called device of the call.

44. A communication method, characterized in that: The method comprises: receiving a second message, wherein the second message includes an identifier of the first device, an identifier of the second device, and fourth information, wherein the fourth information is used to request the first device and the second device to exchange call data on the satellite; Based on the second condition, fifth information is sent to the first core network element serving the first device, wherein the fifth information is used to instruct the first device and the second device to exchange call data on the satellite, wherein the first core network element serving the first device also serves the second device, or the first core network element serving the first device does not serve the second device.

45. The method according to claim 44, characterized in that The first core network element serving the first device does not serve the second device, and the method further includes: Send sixth information to a first core network element serving the second device, where the sixth information is used to instruct the first device and the second device to exchange call data on the satellite.

46. ​​The method according to claim 44 or 45, characterized in that The second condition includes one or more of the following: The second core network element serving the IMS PDU session of the first device is the same as the second core network element serving the IMS PDU session of the second device; The first core network element serving the IMS PDU session of the first device is the same as the first core network element serving the IMS PDU session of the second device; The first device and the second device both access the network via a satellite; Determining that the first device and the second device are located under the same satellite; or, It is determined that the first device and the second device are located under different satellites, and that there is an inter-satellite link between the different satellites.

47. The method according to any one of claims 44 to 46, characterized in that The method further includes: receiving a third message, the third message including an identifier of the first device, an identifier of the second device, and the fourth information; Based on the second condition, sending fifth information to the first core network element serving the first device includes: based on the second condition, the second message and the third message, sending the fifth information to the first core network element serving the first device.

48. The method according to any one of claims 44 to 47, characterized in that The method further comprises: Determine that a second core network element serving the IMS PDU session of the first device is different from a second core network element serving the IMS PDU session of the second device, and / or a first core network element serving the IMS PDU session of the first device is different from a first core network element serving the IMS PDU session of the second device; Sending first rejection information to the IMS network element, where the first rejection information is used to indicate rejection of exchanging call data between the first device and the second device on the satellite.

49. The method according to any one of claims 44 to 48, characterized in that The method further comprises: receiving eighth information from a first core network element serving an IMS PDU session of the first device, the eighth information being used to indicate a configuration result for exchanging call data between the first device and the second device on a satellite; Sending seventh information to the IMS network element, where the seventh information is used to indicate a configuration result for exchanging call data between the first device and the second device on the satellite.

50. The method according to claim 49, characterized in that Before sending the eighth information to the IMS network element, the method further includes: Receive ninth information from a first core network element serving an IMS PDU session of the second device, where the ninth information is used to indicate a configuration result for exchanging call data between the first device and the second device on a satellite.

51. A communication method, characterized in that: The method comprises: receiving information from a second core network element, wherein the information is used to instruct the first device and the second device to exchange call data on a satellite; Based on the third condition, third configuration information is sent to the first user plane function entity, and the third configuration information is used to configure the first user plane function entity to directly forward call data between the first device and the second device. The first user plane function entity is deployed on a satellite, and the first user plane function entity serves the first device, or the first user plane function entity serves the first device and the second device.

52. The method according to claim 51, characterized in that The first user plane function entity serves the first device, and the method further includes: Send fourth configuration information to a second user plane function entity, wherein the fourth configuration information is used to configure the second user plane function entity to directly forward call data between the first device and the second device, the second user plane function entity being deployed on a satellite, and the second user plane function entity serving the second device.

53. The method according to claim 51 or 52, characterized in that The third condition includes one or more of the following: The first device and the second device both access the network via a satellite; The first device and the second device are served by a same user plane function entity, and the same user plane function entity is deployed on a satellite; The first device and the second device are served by different user plane function entities, the different user plane function entities are deployed on the satellite, and the different user plane function entities can establish data transmission channels; The first device and the second device are located under the same satellite; or, The first device and the second device are located under different satellites, and there is an inter-satellite link between the different satellites.

54. A communication method, characterized in that: The method comprises: Sending second information to the IMS network element, where the second information is used to request to exchange call data on the satellite.

55. A communication device, characterized in that: The communication device includes a processing unit and a transceiver unit, and the processing unit is coupled to the transceiver unit to execute the method as described in any one of claims 1 to 5, or the method as described in any one of claims 6 to 15, or the method as described in any one of claims 16 to 18, or the method as described in any one of claims 19 to 29, or the method as described in any one of claims 30 to 32, or the method as described in any one of claims 33 to 43, or the method as described in any one of claims 44 to 50, or the method as described in any one of claims 51 to 53, or the method as described in claim 54.

56. A communication device, characterized in that: The communication device includes a processor and a memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the communication device performs the method according to any one of claims 1 to 5, or the communication device performs the method according to any one of claims 6 to 15, or the communication device performs the method according to any one of claims 16 to 18, or the communication device performs the method according to any one of claims 19 to 29, or the communication device performs the method according to any one of claims 30 to 32, or the communication device performs the method according to any one of claims 33 to 43, or the communication device performs the method according to any one of claims 44 to 50, or the communication device performs the method according to any one of claims 51 to 53, or the communication device performs the method according to claim 54.

57. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store a computer program. When the computer program is run on a computer, the computer executes the method as claimed in any one of claims 1 to 5, or the method as claimed in any one of claims 6 to 15, or the method as claimed in any one of claims 16 to 18, or the method as claimed in any one of claims 19 to 29, or the method as claimed in any one of claims 30 to 32, or the method as claimed in any one of claims 33 to 43, or the method as claimed in any one of claims 44 to 50, or the method as claimed in any one of claims 51 to 53, or the method as claimed in claim 54.

58. A computer program product, characterized in that The computer program product comprises a computer program, which, when executed on a computer, enables the computer to execute the method as claimed in any one of claims 1 to 5, or the method as claimed in any one of claims 6 to 15, or the method as claimed in any one of claims 16 to 18, or the method as claimed in any one of claims 19 to 29, or the method as claimed in any one of claims 30 to 32, or the method as claimed in any one of claims 33 to 43, or the method as claimed in any one of claims 44 to 50, or the method as claimed in any one of claims 51 to 53, or the method as claimed in claim 54.

59. A chip system, characterized in that: The chip system comprises: A processor and an interface, the processor being used to call and run instructions from the interface, and when the processor executes the instructions, implementing the method as claimed in any one of claims 1 to 5, or implementing the method as claimed in any one of claims 6 to 15, or implementing the method as claimed in any one of claims 16 to 18, or implementing the method as claimed in any one of claims 19 to 29, or implementing the method as claimed in any one of claims 30 to 32, or implementing the method as claimed in any one of claims 33 to 43, or implementing the method as claimed in any one of claims 44 to 50, or implementing the method as claimed in any one of claims 51 to 53, or implementing the method as claimed in claim 54.

60. A communication system, characterized in that: The communication system includes a first core network element and an IMS network element, wherein: The first core network element is used to execute the method according to any one of claims 1 to 5; The IMS network element is used to execute the method according to any one of claims 6 to 15.

61. The communication system according to claim 60, characterized in that The communication system further comprises a UPF, wherein: The UPF is used to perform the method according to any one of claims 16 to 18.

62. A communication system, characterized in that: The communication system includes an IMS network element and a communication device, wherein: The IMS network element is used to execute the method according to any one of claims 19 to 29; The communication device is used to execute the method according to any one of claims 30 to 32.

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