Communication method and apparatus

Abstract

The present application relates to a communication method and apparatus. The method comprises: a first IMS network element receiving a first call request from a first apparatus, wherein the first call request is used for requesting the execution of a call service with a second apparatus; and the first IMS network element determining that the first apparatus executes the call service by means of using a first coding mode, wherein the first coding mode corresponds to a satellite access mode; and the first apparatus accessing a network by means of a satellite. In the embodiments of the present application, a first coding mode is set for a satellite access mode, and if a media negotiation process is to be executed, since the coding mode of a first apparatus is known, it is not necessary for the first apparatus to participate in the media negotiation process. Thus, a satellite-ground signaling transmission process is reduced by the media negotiation process, such that the efficiency of media negotiation is improved, and the latency of a call service can be effectively reduced.

Description

A communication method and apparatus

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410320286.5, filed on March 19, 2024, entitled "A Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0004] Currently, user equipment (UE) can conduct calls via the Internet Protocol (IP) Multimedia Subsystem (IMS). For example, the UE first registers with the network in the 5th generation (5G) system, establishing an IMS protocol data unit (PDU) session to carry call data and signaling. This process mainly involves the interaction between the UE and the 5G core network (5GC). Afterward, the UE initiates IMS registration with the IMS through the established IMS PDU session, establishing an IMS session, and then performs call services through this IMS session.

[0005] During a call, the calling UE and the called UE must first perform media negotiation to determine the media information used for the call. If the UE accesses the network via satellite, the media negotiation process also involves signaling transmission between the satellite and the ground, resulting in a longer negotiation time and greater latency for the call. Summary of the Invention

[0006] This application provides a communication method and apparatus for reducing the latency of voice calls.

[0007] In a first aspect, a first communication method is provided. This method can be executed by an IMS network element, or by other devices including IMS network element functionality, or by a chip system (or chip) or other functional module capable of implementing the IMS network element's functionality. The chip system or functional module is, for example, located within the IMS network element. Optionally, the IMS network element is, for example, a P-CSCF or S-CSCF, or other network elements within the IMS. The IMS network element involved in the first aspect is, for example, a first IMS network element. In the following description, the method being executed by the first IMS network element is taken as an example. The method includes: receiving a first call request from a first device, the first call request being used to request to perform a call service with a second device, the first device accessing the network via satellite; determining that the first device performs the call service using a first encoding method, the first encoding method corresponding to the satellite access method.

[0008] This application embodiment sets a first encoding method for satellite access. For example, if it is determined that the first device accesses the network via satellite, it can be determined that the first device is performing call services using the first encoding method. If a media negotiation process needs to be performed, since the encoding method of the first device is known, the first device does not need to participate in the media negotiation process again; for example, the signaling of the media negotiation process does not need to be transmitted to the first device. Therefore, this media negotiation process reduces the signaling transmission process between satellite and ground, improves the efficiency of media negotiation, and can effectively reduce the latency of call services.

[0009] In one optional implementation, the data transmission rate corresponding to the first encoding method is less than or equal to a first threshold. This can be understood as the first encoding method being a low-rate encoding method. For example, if the data transmission rate corresponding to the first encoding method is low, the signaling overhead of the call data using the first encoding method is low, making the first encoding method suitable for communication networks with low bandwidth or limited resources.

[0010] In one optional implementation, the network is a narrowband network. Optionally, the narrowband network may be, for example, NB-IoT, or other narrowband networks. Furthermore, the embodiments of this application can be applied to narrowband networks or broadband networks, without limitation.

[0011] In an optional implementation, the method further includes: determining, based on first information included in the first call request, that the first device accesses the network via satellite, wherein the first information indicates the mode of network access for the first device; or, receiving a registration request from the first device and determining, based on second information included in the registration request, that the first device accesses the network via satellite, wherein the second information indicates the mode of network access for the first device; or, receiving fifth information from a third core network element and determining, based on the fifth information, that the first device accesses the network via satellite, wherein the fifth information indicates the mode of network access for the first device. The first IMS network element can determine the mode of network access for the first device using various methods. For example, it can be determined through the first call request, or through the registration request of the first device, or through information from the core network element, offering greater flexibility.

[0012] In an alternative implementation, the first call request does not include information about the first encoding method. For example, the first IMS network element can determine the method by which the first device accesses the network based on a registration request from the first device or information from a third core network element, without needing to be indicated by the first call request. In this case, the first call request may not include information about the first encoding method, thereby reducing the transmission overhead of the first call request.

[0013] In an optional implementation, the method further includes: sending a second call request to a second IMS network element serving the second device, the second call request indicating the first encoding method (e.g., the second call request includes information about the first encoding method), or indicating both the first and second encoding methods (e.g., the second call request includes information about both the first and second encoding methods), the second encoding method being an encoding method supported by the first IMS network element. Upon receiving the first call request, the first IMS network element can then transmit the second call request to the second IMS network element, enabling the information in the first call request to reach the second device. The second call request can specify only the first encoding method without specifying other encoding methods. This is equivalent to eliminating the need for the second device or the second IMS network element to select an encoding method, instead specifying the use of the first encoding method. This reduces the process of the second device or the second IMS network element selecting an encoding method and simplifies the processing of the second device or the second IMS network element. Alternatively, the second call request can specify more encoding methods in addition to the first encoding method, such as specifying the first encoding method and the second encoding method. This is equivalent to providing the second IMS network element or the second device with more encoding methods to choose from. For example, if the second device has strong capabilities or does not access the network via satellite, the second device can use an encoding method with a higher data transmission rate to improve the call performance of the second device.

[0014] In an optional implementation, the method further includes: receiving a first response message from the second IMS network element, the first response message indicating the encoding method supported by the second device (e.g., the first response message includes information about the encoding method supported by the second device); determining the encoding method used by the call service between the second device and the IMS where the first IMS network element is located; and sending a first confirmation message to the second device, the first confirmation message indicating the encoding method used by the call service between the second device and the IMS where the first IMS network element is located. It is evident that during the media negotiation process, since the encoding method of the first device is known, the first device does not need to participate in the media negotiation process again. For example, the signaling of the media negotiation process does not need to be transmitted between the first IMS network element and the first device; instead, the media negotiation process can be performed by the first IMS network element and the second device. If the first device accesses the network via satellite, the first device may be located on the ground, and the signaling interaction between the first IMS network element and the first device may involve a satellite-to-ground signaling transmission process. Since the first device does not participate in the media negotiation process, the signaling transmission between the first IMS network element and the first device is reduced. For example, the signaling transmission between satellite and ground is reduced, which improves the efficiency of media negotiation and can effectively reduce the latency of call services.

[0015] In an optional implementation, the first response message includes third information, and the method further includes: receiving a second response message from the second IMS network element; sending a third response message to the first device according to the second response message, the third response message including the third information, and the third response message further indicating the first encoding method (e.g., the third response message includes information about the first encoding method). If the first response message from the second device is intercepted by the first IMS network element and not sent to the first device (because the first device does not participate in the media negotiation process), and the first response message may include other information besides media negotiation-related information, such as the third information, then after receiving the second response message from the second device, the first IMS network element can add the third information to the third response message and send it to the first device, enabling the first device to perform call services with the second device.

[0016] In an optional implementation, the method further includes: receiving a first response message from the second IMS network element, the first response message including information about the encoding method supported by the second device; and sending a third response message to the first device based on the first response message, the third response message including information about the first encoding method. For example, if the second device does not send a second response message but only sends a first response message, and the encoding method supported by the second device indicated by the first response message is the first encoding method, then the first IMS network element and the second device do not need to negotiate further, but can determine that the call service uses the first encoding method between the first IMS network element and the second device. In this case, the first IMS network element can send a third response message to the first device based on the first response message.

[0017] Secondly, a second communication method is provided, which can be executed by a first device, or by other devices including the functions of the first device, or by a chip system (or chip) or other functional module capable of implementing the functions of the first device, such as being disposed in the first device. The first device is, for example, a calling device in a call service. Optionally, the first device is, for example, a UE. The method includes: determining that a first encoding method is used to perform the call service, the first encoding method corresponding to a satellite access method, wherein the first device accesses the network via a satellite; sending a first call request to a first IMS network element serving the first device through a service link, the first call request being used to request to perform a call service with a second device, and the first call request indicating the first encoding method (e.g., the first call request includes information about the first encoding method).

[0018] In one optional implementation, the data transmission rate corresponding to the first encoding method is less than or equal to a first threshold.

[0019] In one alternative implementation, the network is a narrowband network.

[0020] In an optional implementation, the method further includes: receiving a third response message, the third response message including third information, and the third response message further indicating the first encoding method (e.g., the third response message includes information about the first encoding method).

[0021] For the technical effects of the second aspect or various alternative implementation methods, please refer to the introduction of the technical effects of the first aspect or corresponding implementation methods.

[0022] Thirdly, a third communication method is provided, which can be executed by a second device, or by other devices including the functions of the second device, or by a chip system (or chip) or other functional module capable of implementing the functions of the second device, such as being disposed within the second device. The second device is, for example, a called device in a call service. Optionally, the second device is, for example, a UE. The method includes: receiving a third call request from a second IMS network element via a service link, the third call request being used to request the execution of a call service; determining that the call service is executed using a first encoding method, the first encoding method corresponding to a satellite access method; and sending a fourth response message, the fourth response message being used to indicate the first encoding method (e.g., the fourth response message includes information about the first encoding method).

[0023] In one alternative implementation, sending a fourth response message includes: transmitting call data with the first device, the call data corresponding to the call service, in the absence of other messages (e.g., no other messages received from the second IMS network element), the other messages including messages other than the third call request.

[0024] In an optional implementation, after sending the fourth response message, the method further includes: after receiving the first confirmation message, transmitting call data with the first device, the call data corresponding to the call service.

[0025] In one optional implementation, the data transmission rate corresponding to the first encoding method is less than or equal to a first threshold.

[0026] In one alternative implementation, the network is a narrowband network.

[0027] For information on the technical effects of the third aspect or various alternative implementation methods, please refer to the description of the technical effects of the first aspect or corresponding implementation methods.

[0028] Fourthly, a fourth communication method is provided, which can be executed by an IMS network element, or by other devices including IMS network element functionality, or by a chip system (or chip) or other functional module capable of implementing the IMS network element's functionality, for example, being located within the IMS network element. Optionally, the IMS network element is, for example, a P-CSCF or S-CSCF, or other network elements within the IMS. The IMS network element involved in the second aspect is, for example, a second IMS network element. In the following description, the method being executed by a second IMS network element is taken as an example. The method includes: receiving a second call request from a first IMS network element, the second call request indicating a first encoding method (e.g., the second call request includes information about the first encoding method), or indicating both a first and a second encoding method (e.g., the second call request includes information about both the first and second encoding methods); and, in the case where the second device accesses the network via satellite, sending a third call request to the second device according to the second call request, the third call request indicating the first encoding method but not the second encoding method.

[0029] For example, if the second call request from the first IMS network element indicates both a first and a second encoding method, and the second IMS network element determines, based on the second device's access to the network via satellite, that the second device should use the first encoding method, then the second IMS network element does not need to indicate the second encoding method to the second device; instead, it can simply indicate the first encoding method. This reduces the process of the second device selecting an encoding method and also reduces the transmission overhead of the third call request.

[0030] In one optional implementation, the data transmission rate corresponding to the first encoding method is less than or equal to a first threshold.

[0031] In one alternative implementation, the network is a narrowband network.

[0032] In an optional implementation, the method further includes: receiving a registration request from the second device, and determining, based on fourth information included in the registration request, that the second device accesses the network via satellite; or, receiving sixth information from a fourth core network element, and determining, based on the sixth information, that the second device accesses the network via satellite.

[0033] For the technical effects of the various alternative implementations of the fourth aspect, please refer to the description of the technical effects of the first aspect or the corresponding implementation.

[0034] Fifthly, a fifth communication method is provided. This method can be executed by a core network element, or by other devices including core network element functions, or by a chip system (or chip) or other functional module capable of implementing the core network element functions, for example, being located within a core network element. This core network element is, for example, a first core network element. In the following description, the method being executed by a first core network element is taken as an example. Optionally, the first core network element is, for example, an SMF, or other core network element capable of implementing similar functions. Alternatively, the method 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 capable of implementing the IMS network element functions, for example, being located within an IMS network element. Optionally, the IMS network element is, for example, a P-CSCF or S-CSCF, or other network elements within the IMS. In this context, the IMS network element involved in the second aspect is, for example, a third IMS network element, which may be, for example, the first or second IMS network element involved in the aforementioned aspect. In the following description, the method is described as being executed by a third IMS network element. The method includes: receiving a first request message from a third device, the first request message being used to request registration or to request the establishment of a session; and, in the case that the third device accesses the network via satellite, responding to the first request message by sending first information, the first information being used to establish a first dedicated bearer, wherein the first dedicated bearer is used to transmit the call service of the third device, and the third device is the calling device or the called device of the call service.

[0035] In this embodiment, the first dedicated bearer can be established before the call process (e.g., during the IMS PDU session establishment process or the IMS registration process). Therefore, the process of establishing the first dedicated bearer does not need to be repeated during the call process, thereby reducing call latency. Furthermore, during the call process, the third device can actively activate the first dedicated bearer without the network triggering its activation, reducing signaling interaction between the network and the UE and saving call transmission latency.

[0036] In one optional implementation, the network is a narrowband network. Optionally, the narrowband network may be, for example, NB-IoT, or other narrowband networks. Furthermore, the embodiments of this application can be applied to narrowband networks or broadband networks, without limitation.

[0037] In one optional implementation, the first information is used to establish a first dedicated bearer, including: the first information is used to configure the first dedicated bearer; or, the first information is used to request the core network to configure the first dedicated bearer. For example, the first request message is used to request the establishment of a session. After receiving the first request, the first core network element determines that the call service of the third device is transmitted through the first dedicated bearer, and can then send the first information for configuring the first dedicated bearer. As another example, the first request message is used for registration. After receiving the first request, the third IMS network element determines that the call service of the third device is transmitted through the first dedicated bearer, and can then send the first information for requesting configuration and suspending the first dedicated bearer to the corresponding core network element, thereby allowing the core network element to configure and suspend the first dedicated bearer.

[0038] In an optional implementation, the first information is further used to instruct the suspension of the first dedicated bearer. Since the first dedicated bearer is established before the call process begins but is only used during the call process, it can be suspended first. Therefore, the first information can also instruct the suspension of the first dedicated bearer, thus avoiding the need for further instructions to suspend it via other information, thereby saving signaling overhead.

[0039] In one optional implementation, the first request message is used to request the establishment of a session, and the method further includes: receiving second information, the second information being used to instruct the third device to access the network via satellite. For example, a first core network element can determine the method of network access for the third device based on the second information from the AMF or other core network elements.

[0040] In an optional implementation, the first request message is used to request the establishment of a session, and the method further includes: after the call service is initiated, receiving QoS parameters corresponding to the first dedicated bearer; sending an activation indication, the activation indication being used to instruct the activation of the suspended first dedicated bearer. If the first core network element receives the QoS parameters corresponding to the first dedicated bearer, it indicates that the call service is about to begin, and therefore the first dedicated bearer can be activated, allowing the call service to be transmitted.

[0041] In one alternative implementation, the first request message is used to request registration, and the first request message is also used to instruct the third device to access the network via satellite. For example, the third IMS network element can determine the method of network access for the third device based on the information in the registration request.

[0042] In an optional implementation, the first request message is used to request registration, and the method further includes: after the call service is initiated, receiving a response message from the called device of the call service, the response message being a response to a call request from the calling device of the call service; and sending an activation indication, the activation indication being used to instruct the activation of the suspended first dedicated bearer. If the first IMS network element receives the response message from the called device, it indicates that the call service is about to begin, and therefore the first dedicated bearer can be activated, allowing the call service to be transmitted.

[0043] A sixth aspect provides a sixth communication method, which can be executed by a first device, or by other devices including the functions of the first device, or by a chip system (or chip) or other functional module capable of implementing the functions of the first device, such as being disposed in the first device. The first device is, for example, a calling device in a call service. Optionally, the first device is, for example, a UE. The method includes: sending a first request message, the first request message being used to request registration or to request the establishment of a session; receiving first information, the first information being used to configure a first dedicated bearer, and the first information further being used to indicate suspending the first dedicated bearer, wherein the first dedicated bearer is used to transmit call services. For the technical effects of the sixth aspect, refer to the description of the technical effects of the fifth aspect or corresponding embodiments.

[0044] In an optional implementation, the method further includes: sending a first call request, the first call request being used to request to perform the call service with the second device; and activating the first dedicated bearer. In this embodiment, the first device can activate the first dedicated bearer automatically, without needing network triggering, reducing the signaling transmission process between the network and the first device and saving signaling overhead. If the first device accesses the network via satellite, the signaling transmission between the first device and the network may involve satellite-to-ground transmission; reducing this transmission process can significantly reduce the latency of the call service.

[0045] A seventh aspect provides a seventh communication method. This method can be executed by an IMS network element, or by other devices including IMS network element functionality, or by a chip system (or chip) or other functional module capable of implementing the IMS network element's functionality, for example, being located within the IMS network element. Optionally, the IMS network element is, for example, a P-CSCF or S-CSCF, or other network elements within the IMS. The IMS network element involved in the second aspect is, for example, a third IMS network element, which is, for example, the first or second IMS network element involved in the aforementioned aspect. In the following description, the method is executed by a third IMS network element as an example. The method includes: receiving a first call request from a first device, the first call request being used to request to perform a call service with a second device; before receiving a response message from the second device, sending a first request message to a core network element according to the first device or the second device accessing the network via a satellite, the first request message being used to request the configuration of a first dedicated bearer for transmitting the call service, and the response message being a response to the first call request.

[0046] In the traditional process, the third IMS network element would establish the first dedicated bearer after receiving the response message from the second device. However, in this embodiment, the first dedicated bearer can be established before that. Therefore, the third IMS network element does not need to trigger the establishment of the first dedicated bearer after receiving the response message, which can enable the call service to be transmitted as soon as possible and reduce the latency of the call service.

[0047] In one optional implementation, the network is a narrowband network. Optionally, the narrowband network may be, for example, NB-IoT, or other narrowband networks. Furthermore, the embodiments of this application can be applied to narrowband networks or broadband networks, without limitation.

[0048] In an optional implementation, the method further includes: determining, based on first information included in the first call request, that the first device accesses the network via satellite, wherein the first information indicates the method by which the first device accesses the network; or, receiving a registration request from the first device and determining, based on second information included in the registration request, that the first device accesses the network via satellite, wherein the second information indicates the method by which the first device accesses the network; or, receiving fifth information from a third core network element and determining, based on the fifth information, that the first device accesses the network via satellite, wherein the fifth information indicates the method by which the first device accesses the network. For example, the third IMS network element may be the first IMS network element. The first IMS network element can determine the method by which the first device accesses the network using various methods. For example, it can be determined through the first call request, or through the registration request of the first device, or through information from the core network element, which is quite flexible.

[0049] In an optional implementation, the method further includes: receiving a registration request from the second device, and determining, based on fourth information included in the registration request, that the second device accesses the network via satellite; or, receiving sixth information from a fourth core network element, and determining, based on the sixth information, that the second device accesses the network via satellite. For example, the third IMS network element is the second IMS network element. The second IMS network element can use various methods to determine how the second device accesses the network, which is quite flexible.

[0050] Eighthly, an eighth communication method is provided. This method can be executed by a core network element, or by other devices including core network element functions, or by a chip system (or chip) or other functional module capable of implementing the core network element's functions, for example, being located within a core network element. This core network element is, for example, a first core network element. In the following description, the method being executed by a first core network element is taken as an example. Optionally, the first core network element is, for example, an SMF, or other core network element capable of implementing similar functions. The method includes: receiving a session establishment request from a third device; determining, based on the third device accessing the network via satellite, that the call service of the third device is transmitted via a default bearer, wherein the third device is the calling device or the called device of the call service; and sending first indication information to the third device, the first indication information indicating that the call service is transmitted via the default bearer.

[0051] The embodiments of this application can transmit call services through the default bearer, thus eliminating the need to establish a dedicated bearer for transmitting call services. This reduces the signaling overhead and latency caused by establishing a first dedicated bearer, thereby improving the quality of call services.

[0052] In one optional implementation, the network is a narrowband network. Optionally, the narrowband network may be, for example, NB-IoT, or other narrowband networks. Furthermore, the embodiments of this application can be applied to narrowband networks or broadband networks, without limitation.

[0053] In one optional implementation, after the call service is initiated, the QoS parameters of the call service are received; and it is determined that the third device transmits the call service through the default bearer.

[0054] A ninth aspect provides a ninth communication method, which can be executed by a third device, or by other devices including the functions of a third device, or by a chip system (or chip) or other functional module capable of implementing the functions of the third device, such as being disposed within the third device. The third device is, for example, a calling device or a called device in a call service. Optionally, the third device is, for example, a UE. The method includes: sending a session establishment request; receiving first indication information, the first indication information being used to indicate that a call service is transmitted through a default bearer.

[0055] In one alternative implementation, the third device accesses the network via satellite.

[0056] In one alternative implementation, the network is a narrowband network.

[0057] In one optional implementation, the third device is the calling device of the call service, and the method further includes: after receiving a response message from the called device of the call service, sending a call resource reservation success message to the called device based on the first indication information.

[0058] In one optional implementation, the third device is the called device of the call service, and the method further includes: after receiving a call resource reservation success message from the calling device of the call service, sending a call resource reservation success response to the calling device based on the first indication information.

[0059] For the technical effects of the ninth aspect or various alternative implementations, please refer to the description of the technical effects of the eighth aspect or corresponding implementations.

[0060] A tenth aspect provides a communication device. The communication device may be a first IMS network element as described in any one of the first to ninth aspects. The communication device possesses the functions of the first IMS network element. The communication device may be, for example, a first IMS network element, or a larger device including a first IMS network element, or a functional module within a first IMS network element, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). The transceiver unit is capable of transmitting and receiving functions. When the transceiver unit performs the transmitting function, it may be called a transmitting unit (sometimes also called a transmitting module), and when the transceiver unit performs the receiving function, it may be called a receiving unit (sometimes also called a receiving module). The transmitting unit and the receiving unit may be the same functional module, which is called the transceiver unit and can perform both transmitting and receiving functions; or, the transmitting unit and the receiving unit may be different functional modules, and the transceiver unit is a collective term for these functional modules.

[0061] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a first call request from a first device, the first call request being used to request to perform a call service with a second device; the processing unit is configured to determine that the first device performs the call service using a first encoding method, the first encoding method corresponding to a satellite access method, and the first device accessing the network via a satellite.

[0062] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the first IMS network element described in any one of the first to ninth aspects above.

[0063] Eleventhly, a communication device is provided. The communication device may be a second IMS network element as described in any one of the first to ninth aspects. The communication device possesses the functions of the aforementioned second IMS network element. The communication device may be, for example, a second IMS network element, a larger device including a second IMS network element, or a functional module within a second IMS network element, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0064] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a second call request from a first IMS network element, the second call request indicating a first encoding method, or indicating both a first encoding method and a second encoding method; the processing unit is configured to send a third call request to a second device according to the second call request, wherein when the second device accesses the network via satellite, the third call request indicates the first encoding method and does not indicate the second encoding method.

[0065] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the second IMS network element described in any one of the first to ninth aspects above.

[0066] In a twelfth aspect, a communication device is provided. The communication device may be the first device described in any one of the first to ninth aspects. The communication device possesses the functions of the first device. The communication device may be, for example, a UE, a larger device including a UE, or a functional module within a UE, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0067] In one optional implementation, the processing unit is configured to determine that a first encoding method is used to perform a call service, the first encoding method corresponding to a satellite access method, wherein the first device accesses the network via a satellite; the transceiver unit (or the sending unit) is configured to send a first call request to a first IMS network element serving the first device, the first call request being used to request to perform a call service with the second device, and the first call request indicating the first encoding method.

[0068] In one optional implementation, the transceiver unit (or the sending unit) is configured to send a first request message, the first request message being used to request registration or to request the establishment of a session; the transceiver unit (or the receiving unit) is configured to receive first information, the first information being used to configure a first dedicated bearer, and the first information is also used to indicate suspending the first dedicated bearer, wherein the first dedicated bearer is used to transmit call services.

[0069] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the first device described in any one of the first to ninth aspects.

[0070] In a thirteenth aspect, a communication device is provided. The communication device may be the second device described in any one of the first to ninth aspects. The communication device possesses the functions of the second device. The communication device may be, for example, a UE, a larger device including a UE, or a functional module within a UE, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0071] In one optional implementation, the processing unit is configured to determine that a first encoding method is used to perform the call service, the first encoding method corresponding to a satellite access method, wherein the second device accesses the network via a satellite; the transceiver unit (or the sending unit) is configured to send a fourth response message, the fourth response message being used to indicate the first encoding method.

[0072] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the second device described in any one of the first to ninth aspects.

[0073] In a fourteenth aspect, a communication device is provided. The communication device may be a third IMS network element as described in any of the first to ninth aspects above. The communication device possesses the functions of the aforementioned third IMS network element. The communication device may be, for example, a third IMS network element, a larger device including a third IMS network element, or a functional module within a third IMS network element, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0074] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a first request message from a third device, the first request message being used to request registration; the transceiver unit (or the sending unit) is configured to respond to the first request message by sending first information, the first information being used to establish a first dedicated bearer, wherein the first dedicated bearer is used to transmit the call service of the third device, the first dedicated bearer being determined by the third device through a satellite access network, and the third device being the calling device or the called device of the call service.

[0075] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a first call request from a first device, the first call request being used to request to perform a call service with a second device; the transceiver unit (or the sending unit) is configured to, before receiving a response message from the second device, send a first request message to a core network element via a satellite access network, depending on whether the first device or the second device accesses the network, the first request message being used to request the configuration of a first dedicated bearer for transmitting the call service, and the response message being a response to the first call request.

[0076] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the third IMS network element described in any of the first to ninth aspects above.

[0077] In a fifteenth aspect, a communication device is provided. The communication device may be a first core network element as described in any 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, a first core network element, a larger device including a first core network element, or a functional module within a first core network element, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0078] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a first request message from a third device, the first request message being used to request the establishment of a session; the transceiver unit (or the sending unit) is configured to respond to the first request message by sending first information, the first information being used to establish a first dedicated bearer, wherein the first dedicated bearer is used to transmit the call service of the third device, the first dedicated bearer being determined by the third device through a satellite access network, and the third device being the calling device or the called device of the call service.

[0079] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive a session establishment request from a third device; the processing unit is configured to determine, based on the fact that the third device accesses the network via satellite, that the call service of the third device is transmitted via a default bearer, wherein the third device is the calling device or the called device of the call service; the transceiver unit (or the sending unit) is configured to send first indication information to the third device, wherein the first indication information is used to indicate that the call service is transmitted via the default bearer.

[0080] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the first core network element described in any one of the first to ninth aspects.

[0081] In a sixteenth aspect, a communication device is provided. The communication device may be a third device as described in any of the first to ninth aspects above. The communication device possesses the functions of the aforementioned third device. The communication device may be, for example, a UE, a larger device including a UE, or a functional module within a UE, such as a baseband device or a chip system. 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 called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the description in the tenth aspect.

[0082] In one optional implementation, the transceiver unit (or the sending unit) is configured to send a session establishment request; the transceiver unit (or the receiving unit) is configured to receive first indication information, the first indication information being used to indicate that call services are transmitted through the default bearer.

[0083] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the third device described in any one of the first to ninth aspects.

[0084] In a seventeenth aspect, a communication device is provided, which can be a first IMS network element, or a chip or chip system used in the first IMS network element. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the first IMS network element as described in the preceding aspects.

[0085] Eighteenthly, a communication device is provided, which can be a second IMS network element, or a chip or chip system used in a second IMS network element. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the second IMS network element as described in the above aspects.

[0086] In a nineteenth aspect, a communication device is provided, which may be a first device or a chip or chip system for use in a first device. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the first device as described in the preceding aspects.

[0087] In a twentieth aspect, a communication device is provided, which may be a second device or a chip or chip system for use in a second device. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the second device in the aforementioned aspects.

[0088] In a twenty-first aspect, a communication device is provided, which can be a first core network element, or a chip or chip system used in a first core network element. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the first core network element in the aforementioned aspects.

[0089] In a twenty-second aspect, a communication device is provided, which can be a third IMS network element, or a chip or chip system used in a third IMS network element. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the third IMS network element as described in the preceding aspects.

[0090] In a twenty-third aspect, a communication device is provided, which may be a third device or a chip or chip system for use in a third device. The communication device includes a communication interface and a processor, and optionally, a memory. The memory stores a computer program, and the processor is coupled to the memory and the communication interface. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the third device in the aforementioned aspects.

[0091] In a twenty-fourth aspect, a communication system is provided, comprising a first IMS network element and a second IMS network element. The first IMS network element is used to execute the method described in any one of the first to fourth aspects, and the second IMS network element is used to execute the method described in any one of the first to fourth aspects. For example, the first IMS network element can be implemented using the communication device described in the tenth or seventeenth aspect; the second IMS network element can be implemented using the communication device described in the eleventh or eighteenth aspect.

[0092] In an alternative embodiment, the communication system may further include a first device. The first device is used to perform the method described in any one of the first to fourth aspects. For example, the first device may be implemented using the communication device described in the twelfth or nineteenth aspect.

[0093] In an alternative embodiment, the communication system may further include a second device. The second device is used to perform the method described in any of the first to fourth aspects. For example, the first device may be implemented using the communication device described in the thirteenth or twentieth aspect.

[0094] In a twenty-fifth aspect, another communication system is provided, including a third IMS network element, which is used to perform the method described in any one of the fifth to sixth aspects above. For example, the third IMS network element can be implemented by the communication device described in the fourteenth or twenty-second aspect.

[0095] In an alternative embodiment, the communication system may further include a first device. The first device is used to perform the method described in any of the fifth to sixth aspects above. For example, the first device may be implemented using the communication device described in the thirteenth or twentieth aspect.

[0096] In a twenty-sixth aspect, another communication system is provided, including a first core network element, which performs the methods described in any one of the fifth to sixth aspects above. For example, the first core network element can be implemented using the communication apparatus described in the fifteenth or twenty-first aspect.

[0097] In an alternative embodiment, the communication system may further include a first device. The first device is used to perform the method described in any of the fifth to sixth aspects above. For example, the first device may be implemented using the communication device described in the thirteenth or twentieth aspect.

[0098] In a twenty-seventh aspect, another communication system is provided, including a third IMS network element, which is used to perform the method described in the seventh aspect above. For example, the third IMS network element can be implemented by the communication device described in the fourteenth or twenty-second aspect.

[0099] In a twenty-eighth aspect, another communication system is provided, including a first core network element. The first core network element is used to perform the methods described in any one of the eighth to ninth aspects above. For example, the first core network element can be implemented using the communication apparatus described in the fifteenth or twenty-first aspect.

[0100] In an alternative embodiment, the communication system may further include a third device. The third device is used to perform the method described in any of the eighth to ninth aspects above. For example, the third device may be implemented using the communication device described in the sixteenth or twenty-third aspect.

[0101] In a twentieth aspect, a computer-readable storage medium is provided for storing a computer program or instructions that, when executed, cause the method performed by the first core network element, the first IMS element, the second IMS element, the third IMS element, the first device, the second device, or the third device in the foregoing aspects to be implemented.

[0102] In a thirtieth aspect, a computer program product containing instructions is provided that, when run on a computer, enables the methods described in the above aspects to be implemented.

[0103] In a thirty-first aspect, a chip system is provided, including a processor and an interface, the processor being configured to call and execute instructions from the interface to enable the chip system to implement the methods of the above aspects. Attached Figure Description

[0104] Figure 1A is a schematic diagram of the 5G network architecture;

[0105] Figure 1B is a schematic diagram of an IMS structure;

[0106] Figures 2A to 2C are schematic diagrams of several application scenarios of the embodiments of this application;

[0107] Figures 3, 4, 6, 7, and 8 are flowcharts of several communication methods provided in the embodiments of this application;

[0108] Figure 5 is a flowchart of the overall process of a UE making a call through IMS;

[0109] Figure 9 is a schematic diagram of a device provided in an embodiment of this application;

[0110] Figure 10 is a schematic diagram of another device provided in an embodiment of this application. Detailed Implementation

[0111] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0112] In this application embodiment, the number of nouns, unless otherwise specified, refers to "singular nouns or plural nouns," that is, "one or more." "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single 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, and c can be single or multiple.

[0113] The ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects and are not used to limit the size, content, order, timing, priority, or importance of the multiple objects. Furthermore, the numbering of steps in the various embodiments described in this application is only to distinguish different steps and is not used to limit the order in which the steps are performed. For example, S301 may occur before S302, or may occur after S302, or may occur simultaneously with S302.

[0114] The following explanations of some terms or concepts used in the embodiments of this application are provided to facilitate understanding by those skilled in the art.

[0115] In this embodiment, the terminal device is a device with wireless transceiver capabilities, which can be a fixed device, a mobile device, a handheld device (e.g., a mobile phone), a wearable device, an in-vehicle device, or a wireless device (e.g., a communication module, a modem, or a chip system, etc.) built into the aforementioned devices. The terminal device is used to connect people, objects, machines, etc., and can be widely used in various scenarios, including but not limited to the following: sensing scenarios, cellular communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, machine-to-machine / machine-type communications (M2M / MTC) communication, Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical care, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, drones, robots, and indoor commercial scenarios (such as mobile phone screen mirroring, file sharing, and mobile phone to VR glasses video transmission). When the terminal equipment is applied to V2X, it can also be called a V2X device, such as a smart car, digital car, unmanned car, driverless car, pilotless car, or automobile, self-driving car, or autonomous car, pure electric vehicle (EV), hybrid electric vehicle (HEV), range-extended electric vehicle (REEV), plug-in hybrid electric vehicle (PHEV), new energy vehicle, or roadside unit (RSU). The terminal equipment can also be a device used in D2D communication, such as an electricity meter or water meter.

[0116] Furthermore, in this embodiment, the terminal device can also be a terminal device in an IoT system. IoT is an important component 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.

[0117] The various terminal devices described above, if located in a vehicle (e.g., placed inside or installed inside a vehicle), can all be considered in-vehicle terminal devices, also known as on-board units (OBUs). The terminal device of this application can also be an in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit built into a vehicle as one or more components or units. The vehicle can implement the methods of this application through the built-in in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit.

[0118] The terminal equipment may sometimes be referred to as UE, terminal, access station, UE station, remote station, wireless communication equipment, or user equipment, etc.

[0119] In this application embodiment, the communication device used to implement the terminal device function can be the terminal device itself, or it can be a device capable of supporting the terminal device in implementing the function, such as a chip system. This device can be installed in the terminal device. In the technical solutions provided in this application embodiment, the terminal device is used as an example to describe the technical solutions provided in this application embodiment. Furthermore, for ease of description, the terminal device in this application embodiment is described using a UE as an example.

[0120] The network devices in this application embodiment include, for example, access network devices and / or core network devices. The access network devices are devices with wireless transceiver capabilities, used to communicate with the terminal devices. The access network devices include, but are not limited to, base stations (base transceiver stations (BTS), Node B, evolved Node B (eNodeB) / eNB, or the next generation Node B (gNodeB) / gNB), transmission reception points (TRPs), base stations evolved from the 3rd generation partnership project (3GPP), access nodes in wireless fidelity (Wi-Fi) systems, wireless relay nodes, wireless backhaul nodes, etc. The base stations can be: macro base stations, micro base stations, pico base stations, small cells, relay stations, etc. Multiple base stations can support networks using the same access technology or networks using different access technologies. A base station can contain one or more co-located or non-co-located transmission and reception points. The access network equipment can also be a radio controller, centralized unit (CU), and / or distributed unit (DU) in a cloud radio access network (CRAN) scenario. The access network equipment can also be a server, etc. For example, the network equipment in V2X technology can be a roadside unit (RSU). The following description uses a base station as an example to illustrate the access network equipment. A base station can communicate with a terminal device, or it can communicate with a terminal device through a relay station. A terminal device can communicate with multiple base stations in different access technologies. The core network equipment is used to implement functions such as mobility management, data processing, session management, policy and billing. The names of the equipment implementing core network functions may differ in systems using different access technologies; this application does not limit this. Taking the 5th generation (5G) mobile communication technology 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.

[0121] In the CU-DU architecture, access network equipment can include one or more logical network elements such as a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). CUs and DUs can be separate entities or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio equipment or radio units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs).

[0122] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an open RAN (ORAN) system, CU can also be called open CU (open CU, O-CU), DU can also be called open DU (open DU, O-DU), CU-CP can also be called open CU-CP (open CU-CP, O-CU-CP), CU-UP can also be called open CU-UP (open CU-CP, O-CU-UP), and RU can also be called open RU (open RU, O-RU). For ease of description, the embodiments of this application use CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in the embodiments of this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0123] In this application embodiment, the communication device used to implement the network device function can be a network device itself, or it can be a device capable of supporting the network device in implementing that function, such as a chip system. This device can be installed within the network device. In the technical solutions provided in this application embodiment, the example of a network device being used to implement the network device function is used to describe the technical solutions provided in this application embodiment.

[0124] The technical features involved in the embodiments of this application are described below.

[0125] During a call service executed via IMS, the calling UE and the called UE first perform media negotiation to determine the media information used for the call service, including the encoding method. The current media negotiation process involves two rounds of signaling interaction between the calling and called UEs. For example, in the first round of signaling interaction, the calling UE sends a call request, which includes the media information supported by the calling UE. This call request reaches the called UE via the calling party's IMS and the called party's IMS. After receiving the call request, the called UE sends a media response to the calling UE, which includes the media information supported by the called UE. This media response reaches the calling UE via the called party's IMS and the calling party's IMS, thus completing the first round of signaling interaction. Next, the calling UE sends a media response confirmation, for example, called media response confirmation a. This media response confirmation a may include the media information selected by the calling UE, for example, the calling UE selects media information based on the media information supported by both the calling and called UEs, and sends this confirmation to the called UE. The media response confirmation 'a' reaches the called UE via the calling party's IMS and the called party's IMS. Upon receiving media response confirmation 'a', the called UE sends a media response confirmation to the calling UE, for example, called media response confirmation 'b'. This media response confirmation 'b' confirms the media information indicated by media response confirmation 'a'. This media response confirmation 'b' reaches the calling UE via the called party's IMS and the calling party's IMS, thus completing the second round of signaling interaction and the media negotiation process.

[0126] If the UE participating in media negotiation (e.g., the calling UE) accesses the network via satellite, the media negotiation process may involve signaling transmission between satellite and ground, resulting in a longer duration of the media negotiation process and significant latency for the call service.

[0127] Therefore, this application embodiment sets a first encoding method for satellite access. For example, if it is determined that the first device accesses the network via satellite, it can be determined whether the first device uses the first encoding method to perform the call service based on information such as the transmission bandwidth and rate supported by the satellite access method. If a media negotiation process needs to be performed, since the encoding method of the first device is known, the first device does not need to participate in the media negotiation process again. For example, the signaling of the media negotiation process does not need to be transmitted to the first device. Thus, the media negotiation process reduces the signaling transmission process between satellite and ground, improves the efficiency of media negotiation, and can effectively reduce the latency of the call service.

[0128] The technical solutions provided in this application can be applied to fourth-generation (4G) mobile communication systems, such as Long Term Evolution (LTE) systems, or to fifth-generation (5G) mobile communication systems, such as NR systems. They can also be applied to next-generation mobile communication systems or other similar communication systems, such as future communication systems, without specific limitations. Furthermore, the technical solutions provided in this application can be applied to sidelinks (SL). For example, this SL belongs to a D2D scenario, such as an NR-D2D scenario, or to a V2X scenario, such as an NR-V2X scenario. For example, the embodiments of this application can be used in fields such as factory manufacturing, smart homes, intelligent driving, assisted driving, intelligent connected vehicles, or indoor commercial scenarios.

[0129] Please refer to Figure 1A, which is a schematic diagram of a 5G network architecture, and is also a network architecture applied in the embodiments of this application. Figure 2A shows the interaction relationships between network functions and entities, as well as the corresponding interfaces. For example, the UE and AMF can interact through the N1 interface, and the interaction message is called an N1 message. Some interfaces in Figure 1A can be implemented using service-oriented interfaces. Figure 1A includes network slice selection function (NSSF), network exposure function (NEF), network repository function (NRF), PCF, unified data management (UDM), application function (AF), AMF, SMF, UE, (R)AN, UPF, data network (DN), etc.

[0130] In Figure 1A, the UE, (R)AN, UPF, and data network (DN) are generally referred to as data plane network functions and entities. User data traffic can be transmitted through protocol data unit (PDU) sessions established between the UE and DN, passing through the (R)AN and UPF network function entities. The other parts in Figure 1A are referred to as control plane network functions and entities, mainly responsible for authentication and authorization, registration management, session management, mobility management, and policy control, thereby achieving reliable and stable transmission of user layer traffic. The user plane is used for carrying service data, while the control plane is used for carrying signaling messages.

[0131] Access network elements, such as (R)AN, are primarily responsible for functions such as radio resource management, quality of service management, data compression, and encryption on the air interface side. These access network devices can include various types of base stations, such as macro base stations, micro base stations, relay stations, and access points. In systems employing different radio access technologies, the names of devices with base station functions may differ; for example, in 5G systems, they are called gNBs.

[0132] The Access and Mobility Management Entity (AMF) is a core network element 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 network elements in the core network, and is responsible for maintaining and managing the UE's state information. When the AMF provides services for a UE's session, it provides control plane storage resources for that session to store the session identifier, the associated SMF network element identifier, etc.

[0133] SMF, Session Management Entity, is responsible for the signaling processing portion of session management, including 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.

[0134] The User Plane Entity (UPF) is responsible for forwarding and receiving user data in the User Equipment (UE). It can receive user data from the Data Network Entity (DN) and transmit it to the UE through access network elements. The UPF can also receive user data from the UE through access network elements and then forward that data to the DN. The transmission resources and scheduling functions within the UPF that provide services to the UE are managed and controlled by the Service Provider Function (SMF).

[0135] DN, for example, carrier services such as IMS, internet access, or third-party services.

[0136] PCF is responsible for policy control decisions, providing policy rules for control plane functions, as well as traffic-based billing control functions.

[0137] UDM is primarily responsible for managing UE subscription data, including the storage and management of UE identifiers and UE access authorization.

[0138] The interfaces between network element functions involved in the embodiments of this application include:

[0139] N1: The interface between the UE and the core network control plane.

[0140] N2: Communication interface between (R)AN and the core network control plane.

[0141] N3: The communication interface between (R)AN and UPF, used to transmit user plane data.

[0142] N4: Communication interface between SMF and UPF, used by SMF to configure policies for UPF, etc.

[0143] N6: Communication port between UPF and DN.

[0144] Please refer to Figure 1B, which is a schematic diagram of an IMS structure. This network architecture is also one of the network architectures used in the embodiments of this 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 (P-CSCF), service-call session control function (S-CSCF), telecom application server (TAS), interconnection border control functions (IBCF), breakout gateway control function (BGCF), media gateway control function (MGCF), and called party (B party), etc. Figure 1B shows two transmission paths. The bold solid line shows the control plane transmission path, and the dashed line shows the media plane transmission path. In addition, Sh, Cx, Rx, N5, Mw, ISC, N5, etc. in Figure 1B all represent interface names.

[0145] The P-CSCF is the first access point in IMS. The P-CSCF behaves like a proxy, accepting requests and serving them internally or forwarding them upwards.

[0146] The S-CSCF performs session control services for the UE. It maintains session state as needed by the network operator to support services.

[0147] This application embodiment can utilize non-terrestrial network (NTN) technology. As one possible application scenario, an NTN system can include a satellite system. Based on satellite altitude, i.e., satellite orbital altitude, satellites can be categorized into highly elliptical orbit (HEO) satellites, geosynchronous orbit (GEO) satellites, medium Earth orbit (MEO) satellites, and low Earth orbit (LEO) satellites, etc. Furthermore, an NTN system can also include non-terrestrial network equipment such as high altitude platform stations (HAPS). The non-terrestrial network equipment involved in this application embodiment is not limited to the examples above. The non-terrestrial network equipment in this application can also be referred to as airborne network equipment.

[0148] Based on the architecture shown in Figures 1A and 1B, please refer to Figures 2A to 2C for several NTN network architectures used in the embodiments of this application.

[0149] Based on the deployment scenarios of satellite and terrestrial networks, satellite network architectures can be divided into three categories: transparent satellite architecture, satellite backhaul architecture, and regenerative satellite architecture. An architecture where the UE connects to the terrestrial access network via satellite can be called a transparent satellite architecture (e.g., Figure 2A). An architecture where the UE connects to the terrestrial access network and then connects to the terrestrial network via satellite can be called a satellite backhaul architecture (e.g., Figure 2B). Additionally, an architecture where the access network equipment is located on a satellite (or the satellite has the functionality of access network equipment) is called a regenerative satellite architecture (e.g., Figure 2C).

[0150] In a transparent satellite architecture, the UE accesses the network via satellite, which can be understood as the UE connecting to a terrestrial network via a satellite. In a regenerative satellite architecture, the UE accesses the network via satellite, which can be understood as the UE connecting to an access network element located on the satellite, or as the UE connecting to a satellite with access network element functionality.

[0151] In Figure 2A, the network equipment used for transmitting services (such as access network equipment and / or core network equipment) are all located on the ground. The UE accesses the network through the access network equipment located on the ground via satellite, which has a pass-through function.

[0152] In Figure 2B, the access network equipment is located on the ground. The UE communicates with the satellite through the ground access network and then connects to the ground network through the satellite.

[0153] In Figure 2C, the access network equipment is located on a satellite, or the underlying processing module of the access network equipment is located on a satellite, or the satellite has some or all of the functions of the access network equipment. Besides the access network equipment, other network equipment used for transmitting services (such as core network equipment) is located on the ground. Alternatively, some or all of the equipment in the core network can also be located on a satellite, or the satellite can have some or all of the functions of the equipment in the core network.

[0154] Alternatively, all or part of the network elements (including one or more of the access network equipment, core network equipment, or IMS network elements) used for transmitting voice services may be located on the satellite, and this application embodiment does not limit this.

[0155] In addition, Figures 2A to 2C are examples of calling UE and called UE accessing the network through the same satellite.

[0156] To better illustrate the embodiments of this application, the methods provided by the embodiments of this application are described below with reference to the accompanying drawings. In various embodiments of this application, transmitting a call service can also be understood as transmitting the call data corresponding to the call service. The call data includes, for example, voice data and / or video data and / or IMS data channel data. In various embodiments of this application, the IMS network element may include one or more network elements located within the IMS, such as P-CSCF, S-CSCF, etc., which can all be referred to as IMS network elements.

[0157] Various embodiments of this application relate to a first device and a second device, where the first device is the calling device for a call service, and the second device is the called device for a call service. The first device may be, for example, a UE or a functional module (e.g., a chip) within a UE, or a network device or a functional module (e.g., a chip) within a network device; the second device may be, for example, a UE or a functional module (e.g., a chip) within a UE, or a network device or a functional module (e.g., a chip) within a network device. The following description assumes that both the first and second devices are UEs; that is, "first UE" can be replaced with "first device," and "second UE" can be replaced with "second device."

[0158] Unless otherwise specified below, the steps indicated by dashed lines in the accompanying drawings of the various embodiments of this application are all optional steps.

[0159] The methods provided in the various embodiments of this application can be applied to the network architecture shown in any of Figures 2A to 2C. For example, the first UE involved in the various embodiments of this application can be the calling UE shown in any of Figures 2A to 2C; the second UE involved in the various embodiments of this application can be the called UE shown in any of Figures 2A to 2C; the IMS network element involved in the various embodiments of this application can be the P-CSCF in the IMS shown in any of Figures 2A to 2C, or the IM shown in any of Figures 2A to 2C. The S-CSCF in S, or any other network element in the IMS shown in any of Figures 2A to 2C besides the P-CSCF and S-CSCF; the first core network element involved in the various embodiments of this application can be the SMF in the core network shown in any of Figures 2A to 2C. In the following description, the first core network element is the SMF as an example; the second core network element involved in the various embodiments of this application can be the PCF in the core network shown in any of Figures 2A to 2C. In the following description, the second core network element is the PCF as an example.

[0160] This application provides a first communication method, as shown in Figure 3, which is a flowchart of the method.

[0161] S301. The first UE determines that the first UE uses the first encoding method to perform the call service.

[0162] For example, since the first UE accesses the network via satellite, it can determine that it will use a first encoding method to perform a call service. The first encoding method is, for example, an encoding method corresponding to the satellite access method, which is the method of accessing the network via satellite. Essentially, this application embodiment sets a corresponding (or associated) first encoding method for the satellite access method. This first encoding method is determined, for example, based on information such as the transmission bandwidth and / or data transmission rate supported by the satellite access method. Therefore, if a UE accesses the network via satellite, it can be determined that the UE will use the first encoding method to perform a call service. When performing the call service, since the encoding method used by the UE has been determined, the UE does not need to participate in the media negotiation process. That is, even if the media negotiation process is performed, the signaling involved in the process does not need to reach the UE, thereby reducing the signaling transmission process between the UE and other network elements, reducing call service latency, and saving signaling overhead. Especially when the UE accesses via satellite, if the UE participates in the media negotiation process, since the signaling needs to be transmitted to the UE, the media negotiation process may involve one or more satellite-to-ground signaling transmission processes. If the UE does not participate in the media negotiation process, the signaling transmission process between the satellite and the ground is reduced, which can significantly reduce the latency of the call service and also reduce the signaling overhead.

[0163] Optionally, the supported transmission bandwidth and / or data transmission rate may differ for different satellite access methods. For example, the network accessed by the first UE via satellite may be a narrowband network, which may have a supported bandwidth less than or equal to a second threshold. For instance, S301 could also be replaced by the first UE determining that it will use a first encoding method to perform call services based on its access to the narrowband network via satellite. Therefore, if the first UE does not access a narrowband network, it may not need to use the first encoding method to perform call services, or the data transmission rate corresponding to the encoding method used may not need to be adapted to the bandwidth supported by the narrowband network. Narrowband networks support limited bandwidth and provide limited network resources; therefore, using a fixed UE encoding method for narrowband networks can reduce signaling overhead during media negotiation and save network resources. Optionally, the narrowband network may be, for example, narrowband (NB)-IoT, or other narrowband networks; there are no restrictions.

[0164] As mentioned above, satellites are also categorized into high-orbit satellites, medium-orbit satellites, and low-orbit satellites. Optionally, in this embodiment, the first UE may access the network via a high-orbit satellite, such as a HEO or GEO satellite. For example, S301 can also be replaced by the first UE determining that it uses a first encoding method to perform call services based on its access to the network via a high-orbit satellite. Therefore, even if the first UE accesses the network via a satellite, it may not use the first encoding method to perform call services if it does not access the network via a high-orbit satellite. High-orbit satellites are far from the ground, offering limited network resources or poor coverage. Therefore, using a fixed encoding method for UEs accessing the network via high-orbit satellites can reduce signaling overhead during media negotiation and save network resources.

[0165] Optionally, if factors such as narrowband networks and high-orbit satellites are considered simultaneously, S301 can also be replaced by the first UE determining the first encoding method for performing call services based on whether the first UE accesses the narrowband network via a high-orbit satellite. Therefore, even if the first UE accesses the network via satellite, if the first UE does not access the network via a high-orbit satellite, and / or does not access a narrowband network, then the first encoding method may not be used to perform call services.

[0166] As an optional implementation, the encoding method in this application embodiment (e.g., the first encoding method) can be a media encoding method corresponding to a call service, such as a voice encoding method or a video encoding method. For example, voice encoding methods include adaptive multi-rate (AMR)-NB or AMR-wideband (WB) encoding methods. In this application embodiment, the encoding method can be understood as corresponding to the data transmission rate or rate range; that is, one encoding method can correspond to one or more data transmission rates, or one or more rate ranges; different encoding methods can correspond to the same or different data transmission rates (or rate ranges). In this case, once the encoding method is determined, the data transmission rate is also determined. For AMR-NB, it can correspond to multiple data transmission rates, such as 1.2 kilobits per second (kbps), 2.4 kbps, or 4.75 kbps, etc. For example, the AMR-NB encoding method corresponding to 1.2k can be called AMR(-NB)1.2k; the AMR-NB encoding method corresponding to 2.4kbps can be called AMR(-NB)2.4k; the AMR-NB encoding method corresponding to 4.75kbps can be called AMR(-NB)4.75k, and so on.

[0167] For example, the data transmission rate corresponding to the first encoding method can be less than or equal to a first threshold. This can be understood as the first encoding method being a low-rate encoding method. For example, by using the first threshold, the first encoding method can be made suitable for communication networks with smaller bandwidth, such as NB-IoT. Once it is determined that the first UE adopts the first encoding method, the data transmission rate corresponding to the first encoding method can be determined, and this data transmission rate is less than or equal to the first threshold. For example, if the first encoding method is AMR(-NB)1.2k, the corresponding data transmission rate is 1.2kbps; or, for example, if the first encoding method is AMR(-NB)2.4k, the corresponding data transmission rate is 2.4kbps; or, for example, if the first encoding method is AMR(-NB)4.75k, the corresponding data transmission rate is 4.75kbps, etc.

[0168] In the following introduction, taking the correspondence between encoding method and rate or rate range as an example, the first UE or other network element can determine the encoding method.

[0169] S302, the first UE sends a first call request to the first IMS network element. Correspondingly, the first IMS network element receives the first call request from the first UE. For example, the first UE can send the first call request to the first IMS network element via a service link.

[0170] The first IMS network element is, for example, the IMS network element serving the first UE. The first call request can be used to request to perform a call service with the second UE. For example, the first call request is a Session Initialization Protocol (SIP) invitation.

[0171] S303. The first IMS network element determines that the first UE uses the first encoding method to perform the call service.

[0172] Optionally, the first call request may indicate the encoding method adopted by the first UE. For example, the first call request may include information about the first encoding method and / or first information. The information about the first encoding method may include, for example, an identifier and / or index of the first encoding method. For instance, if the first call request is a SIP invite, the SIP invite may include a Session Description Protocol (SDP) offer, and the information about the first encoding method may be included in the SDP offer. Upon receiving the first call request, the first IMS network element can determine that the first UE is using the first encoding method based on the information about the first encoding method or the first information. The first information may be information included in the first call request indicating the method by which the first UE accesses the network. For example, if the first call request includes information about the first encoding method, the first IMS network element can determine that the first UE uses the first encoding method; or, if the first call request does not include information about the first encoding method but includes first information, the first IMS network element can determine the encoding method used by the first UE based on the way the first UE accesses the network. For example, if the way the first UE accesses the network is satellite access network, satellite access narrowband network, high-orbit satellite access network, or high-orbit satellite access narrowband network, the first IMS network element can determine that the first UE uses the first encoding method.

[0173] Alternatively, the first call request may not indicate a first encoding method. The first IMS network element can determine the encoding method used by the first UE based on other information from the first UE. For example, before initiating a call service (e.g., sending the first call request), the first UE has already performed IMS registration in the IMS where the first IMS network element is located. Optionally, the first IMS network element can determine the encoding method used by the first UE based on this IMS registration process. Here, the IMS where the first IMS network element is located refers to the IMS that includes the first IMS network element, that is, the first IMS network element is located within that IMS. For example, during the IMS registration process, the first UE can send a message to the first IMS network element requesting registration. This message, for example, is a registration request. This registration request can be used to request registration with the first IMS network element or to request registration with the IMS where the first IMS network element is located. This registration request includes second information, which can indicate the method by which the first UE accesses the network. The first IMS network element can then determine the encoding method used by the first UE based on the method by which the first UE accesses the network. For example, if the first UE accesses the network via satellite access network, satellite access narrowband network, high-orbit satellite access network, or high-orbit satellite access narrowband network, then the first IMS network element can determine that the first UE adopts the first encoding method.

[0174] Alternatively, the first IMS network element can also determine the encoding method adopted by the first UE based on information from other network elements. For example, the first IMS network element can receive fifth information from the third core network element, which indicates the method by which the first UE accesses the network. The first IMS network element can then determine the encoding method adopted by the first UE based on this method. For instance, if the first UE accesses the network via satellite, narrowband satellite, or high-orbit satellite, the first IMS network element can determine that the first UE uses a first encoding method.

[0175] The third core network element is, for example, a PCF or a UDM. For instance, during the process of the third UE performing IMS registration or IMS PDU session establishment, the first IMS network element can interact with the PCF or UDM to obtain the fifth information. For example, if the third core network element is a PCF, the fifth information can be included in the Npcf_PolicyAuthorization_Create / Update message; or, if the third core network element is a UDM, the fifth information can be included in the Cx_Put Resp / Cx_Pull Resp message.

[0176] S304. The first IMS network element sends a second call request to the second IMS network element. Correspondingly, the second IMS network element receives the second call request from the first IMS network element.

[0177] The second IMS network element is the IMS network element serving the second UE. The second call request can be determined based on the first call request. Optionally, the second call request can indicate a first encoding method but not other encoding methods (e.g., the second call request includes information about the first encoding method but does not include information about other encoding methods), which is equivalent to fixing the encoding method of this call service to the first encoding method; or, the second call request can indicate both the first and second encoding methods (e.g., the second call request includes information about both the first and second encoding methods). The second encoding method can include one or more encoding methods, and it can be an encoding method supported by the first IMS network element, such as an encoding method supported by the transcoding capability of the first IMS network element. The reason why the second call request can indicate a second encoding method is that although the first UE accesses the network via satellite or via a narrowband network or a high-orbit satellite network, the way the second UE accesses the network is still uncertain. For example, the second UE may support more efficient or better encoding methods. Therefore, the first IMS network element can provide multiple encoding methods for the second UE to choose from to improve the call performance of the second UE.

[0178] One of the call requests indicates an encoding method. For example, one indication method is that the call request includes information about the encoding method, such as the identifier and / or index of the encoding method. For example, the second call request is a SIP invite, which may include an SDP offer, and the information about the first encoding method (or, the information about the first encoding method and the information about the second encoding method) may be included in the SDP offer.

[0179] S305. The second IMS network element sends a third call request to the second UE based on the second call request. Correspondingly, the second UE receives the third call request from the second IMS network element.

[0180] The third call request may be determined based on the second call request. Optionally, if the second call request indicates a first encoding method and does not indicate other encoding methods, the third call request may also indicate a first encoding method and not indicate other encoding methods.

[0181] Alternatively, if the second call request indicates the first and second encoding methods, then the third call request can also indicate the first and second encoding methods. This is equivalent to the second IMS network element not processing the request but instead continuing to indicate the encoding method of the second call request to the second UE.

[0182] Alternatively, the second call request may indicate the first and second encoding methods, but the third call request may indicate the first encoding method without indicating the second encoding method. For example, the second call request may indicate both the first and second encoding methods, while the second IMS network element determines that the second UE uses the first encoding method (e.g., the second IMS network element determines that the second UE accesses the network via satellite, or via a narrowband network, or via a high-orbit satellite, or via a narrowband network, thus determining that the second UE uses the first encoding method). Optionally, the second IMS network element may determine the second UE's network access method based on the IMS registration process performed by the second UE within the IMS where the second IMS network element is located. For example, the network access method of the second UE can be determined based on the fourth information included in the registration request from the second UE. The fourth piece of information can indicate the method by which the second UE accesses the network; or, the second IMS network element can receive the sixth piece of information from the fourth core network element, which indicates the method by which the second UE accesses the network. The second IMS network element can then determine the method by which the second UE accesses the network based on the sixth piece of information. The fourth core network element can be a core network element serving the second UE, such as an AMF serving the second UE. (For related content, please refer to the previous introduction on how the first IMS network element determines the method by which the first UE accesses the network). Therefore, the second IMS network element does not need to indicate other encoding methods to the second UE, but only needs to indicate the first encoding method, thereby saving the transmission overhead of the third call request. Here, the IMS where the second IMS network element is located refers to the IMS that includes the second IMS network element; that is, the second IMS network element is located within that IMS.

[0183] For example, the third call request is a SIP invite, which may include an SDP offer, and information about the first encoding method (or, information about the first encoding method and information about the second encoding method) may be included in the SDP offer.

[0184] S306. The second UE sends a fourth response message. Correspondingly, the second IMS network element receives the fourth response message. The fourth response message can indicate the encoding methods supported by the second UE.

[0185] Optionally, the second UE may determine the encoding method supported by the second UE based on one or more of the following: the way the second UE accesses the network, the encoding capability of the second UE, or the encoding method indicated by the SDP offer received by the second UE (e.g., the SDP offer included in the third call request).

[0186] For example, if the second UE accesses the network via satellite, or via a narrowband network, or via a high-orbit satellite, or via a narrowband network, the second UE can determine that it uses the first encoding method. Therefore, regardless of whether the third call request indicates the first encoding method without indicating other encoding methods, or whether the third call request indicates both the first and second encoding methods, the fourth response message can indicate the first encoding method without indicating other encoding methods.

[0187] Alternatively, if the second UE does not access the network via satellite, or the second UE does not access the narrowband network, or the second UE does not access the network via a high-orbit satellite, or the second UE does not access the narrowband network via a high-orbit satellite, then the second UE can determine the encoding method supported by the second UE based on the second UE's encoding capabilities and / or the encoding method indicated by the SDP offer received by the second UE. Regardless of whether the third call request indicates the first encoding method without indicating another encoding method, or the third call request indicates the first encoding method and the second encoding method, the encoding method indicated by the fourth response message may include one or more of the following: the first encoding method, the second encoding method, or other encoding methods besides the first and second encoding methods. For example, if the second UE determines the encoding method it supports based on its encoding capabilities and the encoding method indicated by the received SDP offer, or if it determines the encoding method it supports based on the encoding method indicated by the received SDP offer, then the encoding method indicated by the fourth response message may be a subset of the encoding method indicated by the third call request; or, if the second UE determines the encoding method it supports based on its encoding capabilities, then the encoding method indicated by the fourth response message may be a subset of the encoding method indicated by the third call request, or may include encoding methods not indicated by the third call request.

[0188] The fourth response message may be, for example, SIP183 or SIP180. SIP183 or SIP180 may include an SDP answer or SDP response, and information about the first encoding method (or, information about the first encoding method and information about the second encoding method) may be included in the SDP answer or SDP response. Optionally, if the fourth response message indicates the first encoding method and the second encoding method, then the fourth response message may be SIP183; or, if the fourth response message indicates the first encoding method but not the second encoding method, then the fourth response message may be SIP180. Both SIP183 and SIP180 are temporary response messages defined by the SIP protocol, that is, temporary response messages sent by the called UE (e.g., the second UE) after receiving a call request (e.g., a third call request) from the calling UE. SIP 183 can convey information about the session progress, and is also known as a session progress message; SIP 180 can also be called a ringing message. For example, after the called UE receives a ring, it can send a SIP 180. After passing through the second IMS network element and the first IMS network element, the SIP 180 can reach the calling UE, and the calling UE can generate a ringback tone.

[0189] Optionally, the second IMS network element can also send a first response message to the first IMS network element based on the fourth response message. Correspondingly, the first IMS network element can receive the first response message from the second IMS network element. This step can be referred to in S307. The first response message can indicate the encoding method supported by the second UE. For example, the encoding method indicated by the first response message is consistent with the encoding method indicated by the fourth response message. Through the first response message, the first IMS network element can clearly understand the encoding method supported by the second UE.

[0190] If the fourth response message indicates the first encoding method and does not indicate other encoding methods, then the first response message can also indicate the first encoding method and not indicate other encoding methods (in this case, the fourth response message is, for example, SIP 180, and the first response message is also, for example, SIP 180. For example, for the second UE, this SIP 180 is sent without receiving other messages from the second IMS network element. These other messages may include messages other than the third call request, that is, the second UE can send the SIP 180 after receiving the third call request). This indicates that the second UE only supports the first encoding method, or that the second UE selects to use the first encoding method in the call service. Since the first IMS network element has determined that the first UE also uses the first encoding method in the call service, it is equivalent to the encoding methods used by both the first UE and the second UE in the call service being determined. Therefore, optionally, in this case, the media negotiation process can be considered to have ended, for example, it is not necessary to perform steps S308 and S309, which will be introduced later. In this scenario, the media negotiation process can be completed in one round of signaling interaction, eliminating the need for a second round. This significantly reduces signaling overhead and call latency.

[0191] Optionally, after the media negotiation process concludes, for example after S307, the first IMS network element may also send a third response message to the first UE based on the first response message, as described in S311. This third response message may include third information, which may be information included in the first response message, such as an SDP answer or SDP response included in the first response message. For example, if the first response message includes information related to the call service, but the first response message did not reach the first UE (it can be considered intercepted by the first IMS network element), then the first IMS network element may send the third information from the first response message to the first UE. Optionally, the third response message is SIP180. For example, SIP180 as the third response message may include an SDP answer or SDP response, and the third information may be included in the SDP answer or SDP response. Optionally, the third response message can be used to determine whether to perform a call service with the second UE using the first encoding method. For example, the third response message may also indicate the first encoding method, so that the first UE knows that the call service uses the first encoding method; or, the third response message may not indicate any encoding method, so that the first UE can also know that the call service uses the first encoding method determined by the first UE. This method can reduce the transmission overhead of the third response message.

[0192] For S306, S307 and S311 above, please refer to Case 1 in Figure 3.

[0193] Alternatively, if the fourth response message indicates both the first and second encoding methods, then the first response message can also indicate both the first and second encoding methods. Optionally, the fourth response message may be, for example, SIP 183, and the first response message may also be, for example, SIP 183. In this case, although the encoding method for the call service between the first UE and the IMS where the first IMS network element is located has been determined to be the first encoding method, the encoding method for the call service between the second UE and the IMS where the first IMS network element is located is still uncertain (i.e., it is uncertain whether the first or second encoding method will be used). Therefore, optionally, the first IMS network element can negotiate with the second UE the encoding method for the call service between the second UE and the IMS where the first IMS network element is located. For example, the first IMS network element can determine the encoding method used for the call service between the second device and the IMS where the first IMS network element is located, and this encoding method is considered to be the encoding method that the first IMS network element prefers to choose. Optionally, the first IMS network element can determine the encoding method used by the call service between the second device and the IMS where the first IMS network element is located without sending information about the encoding method supported by the second UE to the first UE. This can be understood as the first UE not participating in the process of negotiating the encoding method. The first IMS network element can send a first confirmation message to the second IMS network element, and the second IMS network element can send a second confirmation message to the second UE based on the first confirmation message, as shown in S308. The first confirmation message and / or the second confirmation message can indicate the encoding method of the call service between the second UE and the IMS where the first IMS network element is located. This encoding method is, for example, a first encoding method or a second encoding method (if the second encoding method includes multiple encoding methods, indicating the second encoding method can be indicating one of the encoding methods). The encoding method indicated by the first confirmation message and / or the second confirmation message can be the encoding method that the first IMS network element prefers to select. For example, the first confirmation message and / or the second confirmation message may include an SDP, which may be a subset of the SDP included in the first response message. For instance, the SDP included in the first confirmation message and / or the second confirmation message may indicate the encoding method of the call service between the second UE and the IMS where the first IMS network element is located. Optionally, the first confirmation message and the second confirmation message may both be SIP provisional response acknowledgement (PRACK), for example. After receiving the second confirmation message, the second UE may send a fifth response message to the second IMS network element. The second IMS network element may then send a sixth response message to the first IMS network element based on the fifth response message, as described in S309. The fifth or sixth response message may indicate the encoding method selected by the second UE, or it may not indicate any encoding method, but rather indicate whether the second UE allows or disallows the use of the encoding method indicated by the aforementioned confirmation message.Optionally, both the sixth and fifth response messages can be SIP PRACK responses (ACK). At this point, the encoding methods used by the first and second UEs in the call service have been determined, and the media negotiation process can be considered complete, equivalent to the media negotiation process being completed through two rounds of signaling interaction. However, the first UE does not need to participate in this media negotiation process; that is, the signaling involved in the media negotiation process does not need to reach the first UE. This reduces the signaling transmission process between the first UE and other network elements (such as the first IMS network element), thereby reducing call service latency and saving signaling overhead.

[0194] Optionally, after the media negotiation process concludes, for example after S309 (for the second UE, for example, after the second UE sends the fifth response message), the second UE can also send a seventh response message to the second IMS network element. The second IMS network element can then send a second response message to the first IMS network element based on the seventh response message, as described in S310. Next, the first IMS network element can send a third response message to the first UE based on the second response message, and the first UE will receive the third response message accordingly, as described in S311. Optionally, the seventh, second, and third response messages can all be SIP 180. For details regarding the third response message, please refer to the preceding description.

[0195] For S306 to S311 above, please refer to Case 2 in Figure 3. Case 1 and Case 2 can be regarded as two parallel schemes.

[0196] Optionally, after S311, the first UE and the second UE can begin transmitting call data corresponding to the call service. For example, in the aforementioned case 1, after the second UE sends the fourth response message, it can transmit call data with the first UE without receiving any other messages from the second IMS network element, resulting in lower call service latency. As another example, in the aforementioned case 1, after the second UE sends the seventh response message, it can transmit call data with the first UE without receiving any other messages from the second IMS network element.

[0197] This application embodiment sets a first encoding method for satellite access. For example, if it is determined that the first UE accesses the network via satellite (or via a narrowband network, or via a high-orbit satellite, or via a narrowband network), it can be determined that the first UE is using the first encoding method to perform the call service. If a media negotiation process needs to be performed, since the encoding method of the first UE is known, the first UE does not need to participate in the media negotiation process again; for example, the signaling of the media negotiation process does not need to be transmitted to the first UE. Therefore, this media negotiation process reduces the signaling transmission process between satellite and ground, improves the efficiency of media negotiation, and can effectively reduce the latency of the call service.

[0198] The technical solution of the embodiment shown in Figure 3 reduces the latency caused by the media negotiation process. However, during call services, in addition to the media negotiation process, the establishment of a dedicated bearer also introduces significant latency. This dedicated bearer is, for example, a voice-dedicated bearer, and its corresponding QoS class identifier (QCI) and 5G QoS identifier (5QI) level is 1. Specifically, during a call service, the calling UE first sends a call request to request a call with the called UE. After receiving the call request, the called UE can send a response message, which reaches the calling UE via the IMS network elements serving both the called and called UEs. Both the IMS network elements serving the calling and called UEs trigger the core network to establish a dedicated bearer for transmitting the call service only after receiving the response message. The establishment of this dedicated bearer involves sending configuration information to the corresponding UE. If the UE accesses the network via satellite, it involves satellite-to-ground signaling transmission, resulting in significant latency.

[0199] To address this, this application provides a second communication method to reduce the latency caused by the establishment process of the dedicated bearer for call services. Please refer to Figure 4, which is a flowchart of this method.

[0200] S401, the third UE sends a first request message. Correspondingly, the SMF receives this first request message.

[0201] The first request message can be used to request the establishment of a session. For example, the first request message can be a session establishment request, and the session requested to be established can be a protocol data unit (PDU) session, or it can be other types of sessions. Taking the session as a PDU session as an example, the session establishment request can be a PDU session establishment request, and the data network name (DNN) included in the PDU session establishment request can indicate IMS. S401 can also be understood as the third UE initiating a session establishment procedure. This session establishment procedure can occur before the call procedure. Refer to Figure 5 for the overall procedure of a UE conducting a call through IMS. As shown in this process, the UE first registers with the core network through the 5G system (5GS) registration process, as shown in "1" of Figure 5. Next, the UE and the core network perform a session establishment process, which can be used to establish a PDU session, as shown in "2" of Figure 5. Since this PDU session can transmit call services between the UE and IMS, it can also be called an IMS PDU session. Then, the UE can register with IMS, as shown in "3" of Figure 5. For example, this process shows that the UE registers with IMS through the IMS registration process. Afterwards, the UE can perform a call process through IMS, as shown in "4" of Figure 5. This call process can include the call establishment process and the data transmission process after the call is established. The media negotiation process and the dedicated bearer establishment process mentioned above can both occur during the call establishment process.

[0202] The third UE is, for example, the first UE or the second UE described above. Since no call service has been initiated at this time, either the first UE or the second UE can execute the technical solution provided in the embodiments of this application; therefore, it is described as the third UE.

[0203] Optionally, the first request message sent by the third UE may first reach the AMF, and then the AMF may send the first request message to the SMF. For example, the AMF may send an Nsmf_PDUSession_CreateSMContext_Request to the SMF. This Nsmf_PDUSession_CreateSMContext_Request can also be regarded as a session establishment request, or the Nsmf_PDUSession_CreateSMContext_Request may include a session establishment request, or include information within the session establishment request.

[0204] S402, SMF determines, based on the fact that the third UE accesses the network via satellite, that the third UE's call service is transmitted through the first dedicated bearer, and / or determines the parameters of the first dedicated bearer used to transmit the third UE's call service.

[0205] Optionally, the SMF can determine, based on the second information from the AMF, whether the third UE accesses the network via satellite, narrowband network, high-orbit satellite, or narrowband network. A description of the determination method can be found in the embodiment shown in Figure 3. The second information, for example, indicates the method by which the third UE accesses the network. For instance, the second information may be included in Nsmf_PDUSession_CreateSMContext_Request, or it may be included in other messages sent by the AMF to the SMF.

[0206] Optionally, in this embodiment, the satellite access network method, satellite access narrowband network method, high-orbit satellite access network method, or high-orbit satellite access narrowband network method can correspond to media information. For example, the satellite access network method or satellite access narrowband network method can correspond to a first encoding method. A description of the first encoding method can be found in the embodiment shown in Figure 3. Therefore, if the third UE accesses the network via satellite, or the third UE accesses the narrowband network via satellite, or the third UE accesses the network via high-orbit satellite, or the third UE accesses the narrowband network via high-orbit satellite, the SMF can determine that the third UE's call service corresponds to the first encoding method. Thus, the SMF can determine the parameters that should be used for the first dedicated bearer used to transmit the call service, including, for example, quality of service (QoS) parameters. Therefore, the SMF can establish the first dedicated bearer based on the determined parameters before the call process begins, without waiting for the call to start.

[0207] S403, SMF sends first information. The first information can be used to establish a first dedicated bearer. For example, in the embodiments of this application, the first information can configure the first dedicated bearer, so the first information can also be called configuration information. For example, the first information may include information for instructing an access network element to configure the first dedicated bearer, and / or information for instructing a third UE to configure the first dedicated bearer, wherein the access network element is an access network element serving the third UE.

[0208] For example, in S403, the SMF sends first information to the AMF; after receiving the first information, the AMF can send the first information to the access network element serving the third UE. The first information sent by the SMF to the AMF can be included in the Namf_Communication_N1N2MessageTransfer. This Namf_Communication_N1N2MessageTransfer can include message A, which is received by the access network element serving the third UE, and / or message B, which is received by the third UE.

[0209] Message A may include information from the first information used to instruct the access network element to configure the first dedicated bearer. For example, the information used to instruct the access network element to configure the first dedicated bearer may include the QoS flow identifier (QFI) corresponding to the first dedicated bearer. For example, message A may be N2 session management (N2 SM information). Message B may include a non-access stratum (NAS) message, which may include information from the first information used to instruct the third UE to configure the first dedicated bearer. For example, the information used to instruct the third UE to configure the first dedicated bearer may include the QFI corresponding to the first dedicated bearer. Message B may be, for example, an N1 session container (SM container).

[0210] Optionally, the first information may also indicate the suspension (or deactivation) of the first dedicated bearer. For example, the first information includes first indication information, which may indicate the suspension (or deactivation) of the first dedicated bearer. The first indication information may also be called dedicated bearer suspension indication information, suspension indication information, or deactivation indication information, etc., and there is no limitation on the name. Taking the inclusion of the first information in Namf_Communication_N1N2 MessageTransfer as an example, if Namf_Communication_N1N2MessageTransfer includes message A, then message A may include the first indication information; if Namf_Communication_N1N2MessageTransfer includes message B, then message B may include the first indication information. For example, if Namf_Communication_N1N2MessageTransfer includes messages A and B, then messages A and B may each include the first indication information, so that both the access network element and the third UE can clearly indicate that the first dedicated bearer should be suspended (or deactivated). Here, taking message B as an example, the SM container may include NAS messages, and the first indication information may be included in the NAS message.

[0211] Suspending (or deactivating) the first dedicated bearer can be understood as the first dedicated bearer being created but unable to transmit data. Accordingly, for access network elements, if the first dedicated bearer is suspended (or deactivated), there is no need to reserve transmission resources for the first dedicated bearer.

[0212] S404, AMF sends the first information to the access network element. Correspondingly, the access network element receives the first information.

[0213] The access network element is, for example, the access network element serving the third UE. The first information sent by the AMF is, for example, included in the N2Message. For example, if the Namf_Communication_N1N2MessageTransfer includes message A, then the N2Message may also include message A, which is, for example, N2 SM information; if the Namf_Communication_N1N2MessageTransfer includes message B, then the N2Message may also include information in message B, for example, the NAS message in message B.

[0214] If the N2Message from the AMF includes the information in message B, the access network element may optionally send this information to the third UE. For example, the access network element may send an Access Layer Resource Setup (AN resource setup) to the third UE, as described in S405. The AN resource setup may include the NAS message. Optionally, the AN resource setup may also include the QFI corresponding to the first dedicated bearer, or include the QFI and first indication information, etc.

[0215] For the third UE, after receiving information from the access network element, it can set the first dedicated bearer to a suspended or deactivated state. For example, the access network element sends information to the third UE to enable the third UE to configure the first dedicated bearer, but the third UE, according to the first indication information, can temporarily not configure the first dedicated bearer, or configure the first dedicated bearer but not transmit data. This processing method can be understood as setting the first dedicated bearer to a suspended or deactivated state. In the suspended or deactivated state, the first dedicated bearer will not be used.

[0216] Through the above process, the first dedicated bearer for transmitting call services is established before the call process begins. Therefore, after the call process starts, it is unnecessary to perform the step of establishing the first dedicated bearer again, thereby reducing the latency of establishing the call service. To clarify how the call process is executed in this application embodiment, optionally, this application embodiment may also include the following steps S406 to S410.

[0217] [Corrected according to Rule 91, April 21, 2025] S406: The first UE sends a first call request. The first call request can reach the second UE via the first IMS network element and the second IMS network element. The first call request can adopt the implementation method provided in the embodiment shown in FIG3, or it can also adopt the conventional implementation method. In S406 of FIG4, the third UE is the first UE as an example.

[0218] S407, The first UE activates the first dedicated bearer.

[0219] For example, the first UE may activate the first dedicated bearer before sending the first call request, or at the same time as sending the first call request, or after the first call request has been sent. For example, if the first UE suspends the first dedicated bearer, specifically by not configuring the first dedicated bearer according to the information used to configure the first dedicated bearer, then activating the first dedicated bearer may include the first UE configuring the first dedicated bearer according to the information used to configure the first dedicated bearer.

[0220] Based on the first call request, the first UE can know that the call service is about to begin transmission. In this case, the first UE can actively activate the first dedicated bearer. That is, in this embodiment, it is not necessary for other devices (such as access network elements, core network elements, or IMS elements) to instruct the first UE to activate the first dedicated bearer; instead, the first UE can actively activate the first dedicated bearer, thereby reducing the signaling interaction process between the first UE and other network elements and saving signaling overhead. Moreover, if the first UE accesses the network via satellite, the interaction between the first UE and other network elements may also involve satellite-to-ground transmission, while this embodiment reduces this transmission process, which can save transmission overhead to a significant extent.

[0221] Optionally, after activating the first dedicated bearer, the first UE can send a calling resource reservation success message to the second UE, or this calling resource reservation success message can also be called a call resource reservation success message. For the second UE, after activating the first dedicated bearer and receiving the calling resource reservation success message, it can also send a called resource reservation success response to the first UE, or this called resource reservation success response can also be called a call resource reservation success response. When the second UE activates the first dedicated bearer will be described in S410 later.

[0222] S408, the second UE sends a response message.

[0223] For example, the response message can reach the second IMS network element and the first IMS network element sequentially. The processing method of the first IMS network element and the second IMS network element after receiving the response message is the same, so it is represented as the third IMS network element in Figure 4. The third IMS network element is, for example, the first IMS network element or the second IMS network element. The response message is, for example, the fourth response message introduced in the embodiment shown in Figure 3, or the seventh response message introduced in the embodiment shown in Figure 3. If the traditional dedicated bearer establishment method is followed, the second IMS network element and the first IMS network element will establish the first dedicated bearer after receiving the response message. However, in the embodiment of this application, the first dedicated bearer has been established in advance. Therefore, the second IMS network element and the first IMS network element do not need to perform the step of establishing the first dedicated bearer after receiving the response message.

[0224] S409. The third IMS network element sends the parameters of the first dedicated bearer to the SMF. Correspondingly, the SMF receives these parameters. These parameters may include, for example, the QoS parameters of the first dedicated bearer.

[0225] For example, in S409, the third IMS network element can send an application function (AF) request to the PCF, which may include parameters of the first dedicated bearer; the PCF sends a policy control and charging (PCC) rule to the SMF, which includes parameters of the first dedicated bearer.

[0226] S410 and SMF send a second instruction message. The second instruction message can instruct the activation of the first dedicated bearer.

[0227] For example, in S410, the SMF can send a second indication message to the AMF, which then sends the second indication message to the access network element serving the third UE. Upon receiving the second indication message, the access network element can activate the first dedicated bearer.

[0228] If the third UE is the called UE, i.e., the second UE, then optionally, the access network element serving the second UE, after receiving the second indication information, can also send the second indication information to the second UE, and the second UE can activate the first dedicated bearer after receiving the second indication information. Alternatively, if the third UE is the second UE, the access network element may not need to send the second indication information to the second UE. For example, after receiving the first call request in S406, the second UE can actively activate the first dedicated bearer without the network triggering the second UE to activate the first dedicated bearer, thereby reducing signaling overhead and saving call latency.

[0229] Alternatively, if the third UE is the calling UE, i.e., the first UE, as described in S407 above, the first UE has already actively activated the first dedicated bearer. Therefore, after receiving the second indication information, the access network element serving the first UE does not need to send the second indication information to the first UE. This reduces signaling overhead and saves call latency.

[0230] In this embodiment, the first dedicated bearer can be established before the call process (e.g., during the IMS PDU session establishment process). Therefore, the process of establishing the first dedicated bearer does not need to be repeated during the call process, thereby reducing call latency. Furthermore, during the call process, the first UE (or both the first UE and the second UE) can actively activate the first dedicated bearer, without the network triggering its activation. This reduces the signaling interaction between the network and the UE, saving transmission latency for the call process.

[0231] This application provides a third communication method, which can also reduce the latency caused by the establishment process of the dedicated bearer for call services. Please refer to Figure 6, which is a flowchart of the method.

[0232] S601, the third UE sends a first request message. Correspondingly, the third IMS network element receives the first request message.

[0233] The first request message is, for example, a registration request, which can be used to request the establishment of a Protocol Data Unit (PDU) session. For example, this registration request is a SIP registration. S601 can also be understood as the third UE initiating an IMS registration process. This IMS registration process can occur before the call process, as shown in Figure 5.

[0234] In this context, the third IMS network element is the IMS network element serving the third UE, which is, for example, the first UE or the second UE described above. Since no call service has been initiated at this time, either the first UE or the second UE can execute the technical solution provided in the embodiments of this application; therefore, it is described as the third UE.

[0235] S602, the third IMS network element determines, based on the third UE's access to the network via satellite, that the third UE's call service is transmitted through the first dedicated bearer, and / or determines the parameters of the first dedicated bearer used to transmit the third UE's call service.

[0236] For example, the first request message may include information indicating the method by which the third UE accesses the network. The third IMS network element may determine the method by which the third UE accesses the network based on this information. For example, the third UE may access the network via satellite, or the third UE may access the narrowband network via satellite, or the third UE may access the network via a high-orbit satellite, or the third UE may access the narrowband network via a high-orbit satellite. For an introduction to the method of determination, please refer to the embodiment shown in Figure 3.

[0237] Optionally, in this embodiment, the satellite access network method, satellite access narrowband network method, high-orbit satellite access network method, or high-orbit satellite access narrowband network method can correspond to media information. For example, the satellite access network method or satellite access narrowband network method can correspond to a first encoding method. A description of the first encoding method can be found in the embodiment shown in Figure 3. Then, if the third UE accesses the network via satellite, or the third UE accesses the narrowband network via satellite, or the third UE accesses the network via high-orbit satellite, or the third UE accesses the narrowband network via high-orbit satellite, the third IMS network element can determine that the third UE's call service corresponds to the first encoding method. Therefore, the third IMS network element can determine the parameters that should be used for the first dedicated bearer used to transmit the call service, such as QoS parameters. Thus, the third IMS network element can trigger (or request) the establishment of the first dedicated bearer before the call process begins, without waiting for the call process to start.

[0238] S603, the third IMS network element sends first information. The first information can be used to establish a first dedicated bearer. For example, in the embodiments of this application, the first information can request the configuration (or establishment) of a first dedicated bearer, so the first information can also be called request information.

[0239] Optionally, the first information may include information for configuring the first dedicated bearer by an access network element, and / or information for configuring the first dedicated bearer by a third UE, wherein the access network element is the access network element serving the third UE. For example, the parameters of the first dedicated bearer mentioned in S602 can be used to configure the first dedicated bearer by an access network element, and / or to configure the first dedicated bearer by a third UE.

[0240] Optionally, the first information may indicate that the first dedicated bearer be suspended (or deactivated). For example, the first information may include first indication information, which may indicate that the first dedicated bearer be suspended (or deactivated). The first indication information may also be called dedicated bearer suspension indication information, suspension indication information, or deactivation indication information, etc., and there is no limitation on the name. For example, the first information may be included in an AF request, the receiving end of which may be a PCF.

[0241] After receiving the AF request, the PCF can send the first message to the SMF. For example, this first message may be included in the PCC rule, as can be found in S604.

[0242] After receiving the first information, the SMF can establish (or configure) the first dedicated bearer. Therefore, optionally, the embodiments of this application may also include S607 to S610.

[0243] S605 and SMF send the first configuration information.

[0244] For example, the first configuration information may include information for configuring the first dedicated bearer for an access network element, and / or information for configuring the first dedicated bearer for a third UE, wherein the access network element is the access network element serving the third UE. Wherein, if the first information includes information for configuring the first dedicated bearer for an access network element, and / or information for configuring the first dedicated bearer for a third UE, then the first configuration information may include the same information as the first information; for example, the first configuration information is the same as the first information. Alternatively, if the first information does not include information for configuring the first dedicated bearer, then the SMF may independently determine the information for configuring the first dedicated bearer for an access network element, and / or the information for configuring the first dedicated bearer for a third UE, and include the determined information in the first configuration information.

[0245] Optionally, the first configuration information may also indicate that the first dedicated bearer be suspended (or deactivated). For example, the first configuration information may include first indication information that indicates that the first dedicated bearer be suspended (or deactivated).

[0246] For more details about S605, such as the SMF sending the first configuration information to the AMF via S605, and other corresponding steps, such as the AMF sending the first configuration information to the access network element via S606, and the access network element sending corresponding information to the third UE via S607, please refer to S403 to S405 in the embodiment shown in Figure 4.

[0247] For the third UE, after receiving information from the access network element (e.g., receiving AN resource setup from the access network element, see S405 in the embodiment shown in Figure 4), it can set the first dedicated bearer to a suspended or deactivated state. For example, the information sent by the access network element to the third UE includes information for the third UE to configure the first dedicated bearer, but the third UE can temporarily not configure the first dedicated bearer according to the first indication information. This processing method can be understood as setting the first dedicated bearer to a suspended or deactivated state. In the suspended or deactivated state, the first dedicated bearer will not be used.

[0248] Through the above process, the first dedicated bearer for transmitting call services is established before the call process begins. Therefore, after the call process starts, it is unnecessary to perform the step of establishing the first dedicated bearer again, thereby reducing the latency of establishing the call service. To clarify how the call process is executed in this embodiment, optionally, this embodiment may also include the following steps S608 to S612.

[0249] S608. The first UE sends a first call request. The first call request can reach the second UE via the first IMS network element and the second IMS network element. The first call request can be implemented using the embodiment shown in Figure 3, or it can be implemented using a conventional method.

[0250] S609, The first UE activates the first dedicated bearer.

[0251] For more information on S609, please refer to S406 of the embodiment shown in FIG4.

[0252] S610, the second UE sends a response message.

[0253] For example, the response message can reach the second IMS network element and the first IMS network element sequentially. The processing method of the first IMS network element and the second IMS network element after receiving the response message is the same, so it is represented as the third IMS network element in Figure 4. The third IMS network element is, for example, the first IMS network element or the second IMS network element. The response message is, for example, the fourth response message introduced in the embodiment shown in Figure 3, or the seventh response message introduced in the embodiment shown in Figure 3. In the traditional dedicated bearer establishment method, both the second IMS network element and the first IMS network element would establish the first dedicated bearer after receiving the response message, but in the embodiment of this application, the first dedicated bearer has been established in advance.

[0254] S611, the third IMS network element sends third information to the SMF. Correspondingly, the SMF receives the third information.

[0255] The third information may include, for example, parameters of the first dedicated bearer, and / or, an activation indication. These parameters may include, for example, QoS parameters of the first dedicated bearer. The activation indication can be used to indicate the activation of the suspended first dedicated bearer. For example, since the first dedicated bearer has already been established, the third information may not include the parameters of the first dedicated bearer, but only the activation indication, thereby saving the overhead of the third information. In S611, the third IMS network element may send an AF request to the PCF, and this third information may be included in the AF request; the PCF may also send a PCC rule to the SMF, and this PCC rule may include, for example, the third information.

[0256] S612, SMF sends a second instruction message. The second instruction message can instruct the activation of the first dedicated bearer.

[0257] For example, in S612, the SMF can send a second indication message to the AMF, which then sends the second indication message to the access network element serving the third UE. Upon receiving the second indication message, the access network element can activate the first dedicated bearer.

[0258] For more information on S612, please refer to S410 of the embodiment shown in FIG4.

[0259] In this embodiment, the first dedicated bearer can be established before the call process (e.g., during the IMS registration process). Therefore, the process of establishing the first dedicated bearer does not need to be repeated during the call process, thereby reducing call latency. Furthermore, during the call process, the first UE (or both the first UE and the second UE) can actively activate the first dedicated bearer, without the network triggering its activation. This reduces the signaling interaction between the network and the UE, saving call transmission latency.

[0260] This application provides a fourth communication method, which can also reduce the latency caused by the establishment process of the dedicated bearer for call services. Please refer to Figure 7, which is a flowchart of the method.

[0261] S701, The first UE sends a first call request. The first call request can be used to request to perform a call service with the second UE.

[0262] The first call request can reach the first IMS network element.

[0263] S702. Before receiving the response message from the second UE, the first IMS network element sends a first request message based on the first UE accessing the network via satellite. Alternatively, before receiving the response message from the second UE, the first IMS network element sends a first request message based on the first UE accessing the narrowband network via satellite. Alternatively, before receiving the response message from the second UE, the first IMS network element sends a first request message based on the first UE accessing the network via a high-orbit satellite. Alternatively, before receiving the response message from the second UE, the first IMS network element sends a first request message based on the first UE accessing the narrowband network via a high-orbit satellite. The first request message may request the configuration (or establishment) of a first dedicated bearer for transmitting the call service of the first UE. For a description of narrowband networks or high-orbit satellites, please refer to the embodiment shown in Figure 3. S702 can also be understood as the first IMS network element triggering the core network serving the first UE to establish (or configure) a first dedicated bearer before receiving the response message from the second UE, or before receiving the response message from the second UE.

[0264] Regarding the method by which the first IMS network element determines the first UE accessing the network, please refer to the relevant introduction of the method by which the first IMS network element determines the first UE accessing the network in the embodiment shown in Figure 3.

[0265] Optionally, in this embodiment, the satellite access network method, satellite access narrowband network method, high-orbit satellite access network method, or high-orbit satellite access narrowband network method can correspond to media information. For example, the satellite access network method or satellite access narrowband network method can correspond to a first encoding method. A description of the first encoding method can be found in the embodiment shown in Figure 3. Therefore, if the first UE accesses the network via satellite, or the first UE accesses the narrowband network via satellite, or the first UE accesses the network via high-orbit satellite, or the first UE accesses the narrowband network via high-orbit satellite, the first IMS network element can determine that the first UE's call service corresponds to the first encoding method. Consequently, the first IMS network element can send a first request message to request the configuration of a first dedicated bearer.

[0266] The receiving end of the first request message can be a core network element serving the first UE, such as an SMF. For example, in S702, the first IMS network element can send a first request message to the PCF serving the first UE. The first request message may include parameters of the first dedicated bearer, such as QoS parameters. The PCF then sends the parameters to the SMF, which may be included in the PCC rules sent by the PCF.

[0267] Upon receiving information from the PCF, such as PCC rules, the SMF can establish a first dedicated bearer. For example, the SMF can send information for configuring the first dedicated bearer. This information may include parameters of the first dedicated bearer. If the first request message includes these parameters, the SMF does not need to determine them automatically; or, if the first request message does not include the parameters but only requests the establishment or configuration of the first dedicated bearer, the SMF can determine these parameters automatically. Further details regarding this establishment process can be found in the embodiments shown in Figures 4 and 6. In this embodiment, since the first dedicated bearer is established during the call flow, it is not necessary to suspend or deactivate it; that is, the first dedicated bearer can be in an active state.

[0268] Optionally, in addition to sending the first request message, the first IMS network element may also send a second call request to the second IMS network element, as described in S703. The second call request is determined based on the first call request. Specifically, the first IMS network element may send the first request message and the second call request simultaneously, or it may send the first request message first and then the second call request, or vice versa. Furthermore, the establishment process of the first dedicated bearer may occur before, during, or after the transmission of the second call request.

[0269] S704. Before receiving the response message from the second UE, the second IMS network element sends a first request message based on the second UE accessing the network via satellite. Alternatively, before receiving the response message from the second UE, the second IMS network element sends a first request message based on the second UE accessing the narrowband network via satellite. Alternatively, before receiving the response message from the second UE, the second IMS network element sends a first request message based on the second UE accessing the network via a high-orbit satellite. Alternatively, before receiving the response message from the second UE, the second IMS network element sends a first request message based on the second UE accessing the narrowband network via a high-orbit satellite. The first request message may request the configuration (or establishment) of a first dedicated bearer for transmitting the second UE's call services. For a description of narrowband networks or high-orbit satellites, please refer to the embodiment shown in Figure 3. In addition, to distinguish it from the first request message in S702, the first request message in S702 can be referred to as first request message A, and the first request message in S704 can be referred to as first request message B.

[0270] Regarding the method by which the second IMS network element determines the access network for the second UE, please refer to the relevant introduction of the method by which the second IMS network element determines the access network for the second UE in the embodiment shown in Figure 3.

[0271] In addition, regarding how the core network element serving the second UE establishes the first dedicated bearer, please refer to the relevant introduction in S702 on the establishment of the first dedicated bearer by the core network element serving the first UE. In this embodiment, since the first dedicated bearer is established during the call process, it is not necessary to suspend or deactivate the first dedicated bearer; that is, the first dedicated bearer can be in an active state.

[0272] If a traditional dedicated bearer establishment method is used, both the second IMS network element and the first IMS network element will establish the dedicated bearer only after receiving the response message. However, in this embodiment, either the first IMS network element or the second IMS network element can establish the first dedicated bearer after receiving the call request from the first UE. That is, although the process of establishing the first dedicated bearer in this embodiment also occurs during the call process, the first dedicated bearer can be established before receiving the response message from the second UE, thereby reducing the latency of the call service.

[0273] Optionally, in addition to sending the first request message B, the second IMS network element may also send a third call request to the second UE, as described in S705. The third call request is determined based on the second call request. Specifically, the second IMS network element may send both the first request message B and the third call request simultaneously, or it may send the first request message B first and then the third call request, or vice versa. Furthermore, the establishment process of the first dedicated bearer may occur before, during, or after the transmission of the third call request.

[0274] After receiving the third call request, the second UE can send a response message, as described in S706. This response message can be, for example, SIP183 or SIP180. Following the traditional procedure, the first and second IMS network elements would establish the first dedicated bearer only after receiving the response message. However, in this embodiment, the first dedicated bearer has already been established beforehand. Therefore, after receiving the response message, the first and second IMS network elements do not need to trigger the establishment of the first dedicated bearer again, allowing for faster transmission of call services and reducing call latency.

[0275] This application provides a fifth communication method, which can also reduce the latency caused by the establishment process of the dedicated bearer for call services. Please refer to Figure 8, which is a flowchart of the method.

[0276] S801, the third UE sends a first request message. Correspondingly, the SMF receives this first request message.

[0277] The first request message is, for example, a session establishment request, which can be used to request the establishment of a PDU session. For instance, this session establishment request is a PDU session establishment request, and the DNN included in the PDU session establishment request can indicate IMS. S801 can also be understood as a third UE initiating a session establishment procedure. This session establishment procedure can occur before the call procedure, as shown in Figure 5.

[0278] The third UE is, for example, the first UE or the second UE described above. Since no call service has been initiated at this time, either the first UE or the second UE can execute the technical solution provided in the embodiments of this application; therefore, it is described as the third UE. Regarding the method of sending the session establishment request, please refer to S401 of the embodiment shown in FIG4.

[0279] S802 and SMF determine that the third UE's call services will be transmitted through a default bearer based on the third UE's access to the network via satellite. This default bearer can be established during the session establishment process.

[0280] Optionally, the SMF can determine, based on the second information from the AMF, whether the third UE accesses the network via satellite, a narrowband network via satellite, a high-orbit satellite, or a narrowband network via a high-orbit satellite. For an explanation of narrowband networks, please refer to the embodiment shown in Figure 3. The second information, for example, indicates the method by which the third UE accesses the network. For instance, the second information may be included in Nsmf_PDUSession_CreateSMContext_Request, or it may be included in other messages sent by the AMF to the SMF.

[0281] If the third UE accesses the network via satellite, or via a narrowband network, or via a high-orbit satellite, or via a narrowband network, it may indicate that the third UE experiences significant latency when performing a call, and / or that the network resources are limited. Therefore, if the third UE accesses the network via satellite, or via a narrowband network, or via a high-orbit satellite, or via a narrowband network, or via a high-orbit satellite, it is not necessary to establish a dedicated bearer for this call service; instead, it can be transmitted through the default bearer. This saves on the signaling overhead associated with establishing a dedicated bearer and also reduces the latency of the call service.

[0282] Optionally, in this embodiment, the satellite access network method, satellite access narrowband network method, high-orbit satellite access network method, or high-orbit satellite access narrowband network method can correspond to the media information. For example, the satellite access network method or satellite access narrowband network method can correspond to the first encoding method, and a description of the first encoding method can be found in the embodiment shown in Figure 3. Alternatively, this embodiment may not limit the media information; for example, it does not limit the encoding method corresponding to the satellite access network, satellite access narrowband network, high-orbit satellite access network, or high-orbit satellite access narrowband network. The first encoding method can be used, or other encoding methods can also be used.

[0283] S803 and SMF send the first indication information. The first indication information can indicate that the call service is transmitted through the default bearer. The first indication information can also be called the default bearer voice transmission indication, or it can have other names, which are not limited.

[0284] Optionally, the first indication information may be included in the information used to configure the default bearer. For example, the SMF sends first information, which can be used to establish (or configure) the default bearer; therefore, the first information may also be called configuration information or default bearer configuration information, etc. The first information may include information for instructing an access network element to configure the default bearer, and / or information for instructing a third UE to configure the default bearer, wherein the access network element is the access network element serving the third UE. In addition, the first information may also include first indication information.

[0285] For example, in S803, SMF sends the first information to AMF, and AMF receives the first information accordingly.

[0286] The first message sent by the SMF to the AMF may be included in the Namf_Communication_N1N2 MessageTransfer. The Namf_Communication_N1N2MessageTransfer may include message A, which is received by the access network element serving the third UE, and / or message B, which is received by the third UE.

[0287] Message A may include information from the first information for configuring the default bearer of the access network element. For example, the information for configuring the default bearer of the access network element may include the QFI corresponding to the default bearer. For example, message A may be N2 SM information. Message B may include a NAS message, which may include information from the first information for configuring the default bearer of the third UE. For example, the information for configuring the default bearer of the third UE may include the QFI corresponding to the default bearer. Message B may be, for example, an SM container.

[0288] The first information may include first indication information. For example, if the first information is included in a Namf_Communication_N1N2 MessageTransfer, and the Namf_Communication_N1N2 MessageTransfer includes message A, then message A may include the first indication information; if the Namf_Communication_N1N2 MessageTransfer includes message B, then message B may include the first indication information. For instance, if the Namf_Communication_N1N2 MessageTransfer includes both message A and message B, then message A and message B may each include the first indication information, enabling both the access network element and the third UE to clearly specify that they want to transmit the call service through the default bearer. Specifically, if message B is an SM container, the SM container may include a NAS message, and the first indication information may be included in that NAS message.

[0289] S804 and AMF send the first information. Correspondingly, the access network element receives the first information.

[0290] The access network element is, for example, the access network element serving the third UE. The first information sent by the AMF is, for example, included in the N2Message. For example, if the Namf_Communication_N1N2MessageTransfer includes message A, then the N2Message may also include message A, which is, for example, N2 SM information; if the Namf_Communication_N1N2MessageTransfer includes message B, then the N2Message may also include information in message B, for example, the NAS message in message B.

[0291] If the N2Message from the AMF includes the information in message B, the access network element may optionally send this information to the third UE. For example, the access network element may send an AN resource setup to the third UE, as described in S805. This AN resource setup may include the NAS message. Optionally, the AN resource setup may also include the QFI corresponding to the default bearer, or include the QFI and first indication information, etc.

[0292] For the third UE, after receiving information from the access network element, it can be determined that the call service will be transmitted through the default bearer. This default bearer is a bearer that is originally established during the session establishment process, so it is not necessary to set the default bearer to a deactivated or suspended state.

[0293] As can be seen, the embodiments of this application do not require the step of establishing a first dedicated bearer; instead, the call service can be transmitted through a default bearer, thereby reducing the latency of establishing the call service. To clarify how the call process is executed in the embodiments of this application, optionally, the embodiments of this application may also include the following steps S806 to S810.

[0294] S806: The first UE sends a first call request. The first call request can reach the second UE via the first IMS network element and the second IMS network element. The first call request can be implemented using the embodiment shown in FIG3, or it can also be implemented using a conventional method. S806 in FIG8 uses the example of the third UE being the first UE, therefore S806 in FIG8 is the third UE sending the first call request. In addition, the IMS network element serving the third UE is called the third IMS network element. Since S806 in FIG8 uses the example of the third UE being the first UE, the third IMS network element in S806 in FIG8 can be the first IMS network element.

[0295] S807, the second UE sends a response message.

[0296] For example, the response message can reach the second IMS network element and the first IMS network element sequentially. The processing method of the first IMS network element and the second IMS network element after receiving the response message is the same, so it is represented as the third IMS network element in Figure 8. The third IMS network element is, for example, the first IMS network element or the second IMS network element. The response message is, for example, the fourth response message introduced in the embodiment shown in Figure 3, or the seventh response message introduced in the embodiment shown in Figure 3. If the traditional dedicated bearer establishment method is followed, both the second IMS network element and the first IMS network element will establish a dedicated bearer for transmitting call services after receiving the response message, but the embodiment of this application does not require a dedicated bearer.

[0297] S808, the third IMS network element sends the parameters of the first dedicated bearer to the SMF. Correspondingly, the SMF receives these parameters. These parameters may include, for example, the QoS parameters of the first dedicated bearer.

[0298] For example, in S808, the third IMS network element can send an AF request to the PCF, which may include parameters of the first dedicated bearer; the PCF sends a PCC rule to the SMF, which includes parameters of the first dedicated bearer.

[0299] Since the SMF determines to transmit call services through the default bearer, it does not need to perform the process of establishing a dedicated bearer, but can instead perform other steps in the call flow. For example, the SMF can send a response message to a third IMS element, as described in S809.

[0300] In S810, the third IMS network element sends a response message. Correspondingly, the third UE receives this response message. To distinguish it from the response message in S807, the response message in S807 can be called response message A, and the response message in S810 can be called response message B. Response message B is, for example, SIP 183, which may include SDP answer or SDP response. In this case, the third UE can be the first UE, and response message B can come from the second UE.

[0301] S811, the third UE (at this time, the third UE is, for example, the first UE) sends a call resource reservation success message to the peer UE (for example, the second UE) according to the first instruction information.

[0302] Since the default bearer has been established, after receiving the response message B from the second UE, the third UE can send a call resource reservation success message to the peer UE (since the third UE is now the first UE, the peer UE refers to the second UE). Alternatively, this call resource reservation success message can also be called a calling resource reservation success message. For example, the first UE sends this call resource reservation success message to the second UE through the default bearer.

[0303] Furthermore, since the default bearer has been established, after receiving the call resource reservation success message, the second UE can send a call resource reservation success response to the first UE, or this call resource reservation success response can also be called a called party resource reservation success response. For example, the second UE sends the call resource reservation success response to the first UE through the default bearer.

[0304] The embodiments of this application can transmit call services through the default bearer, thus eliminating the need to establish a dedicated bearer. This reduces the signaling overhead and latency caused by establishing a dedicated bearer, thereby improving the quality of call services.

[0305] Figure 9 shows a schematic diagram of a communication device provided in an embodiment of this application. The communication device 900 can be a first UE or its circuit system as described in any one of the embodiments shown in Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the first UE in the above method embodiments. Alternatively, the communication device 900 can be a second UE or its circuit system as described in any one of the embodiments shown in Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the second UE in the above method embodiments. Alternatively, the communication device 900 can be a third UE or its circuit system as described in any one of the embodiments shown in Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the third UE in the above method embodiments. Alternatively, the communication device 900 can be a first IMS network element or its circuit system as described in any one of the embodiments shown in Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the first IMS network element in the above method embodiments. Alternatively, the communication device 900 may be the second IMS network element or its circuit system as described in the embodiment shown in any of Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the second IMS network element in the above method embodiments. Alternatively, the communication device 900 may be the third IMS network element or its circuit system as described in the embodiment shown in any of Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the third IMS network element in the above method embodiments. Alternatively, the communication device 900 may be the SMF or its circuit system as described in the embodiment shown in any of Figures 3, 4, 6, 7, or 8, used to implement the method corresponding to the SMF in the above method embodiments. For example, one type of circuit system is a chip system.

[0306] The communication device 900 includes at least one processor 901. The processor 901 can be used for internal processing within the device to implement certain control processing functions. Optionally, the processor 901 includes instructions. Optionally, the processor 901 can store data. Optionally, different processors can be independent devices, located in different physical locations, or located on different integrated circuits. Optionally, different processors can be integrated into one or more processors, for example, integrated on one or more integrated circuits.

[0307] Optionally, the communication device 900 includes one or more memories 903 for storing instructions. Optionally, the memories 903 may also store data. The processor and the memories may be separate or integrated together.

[0308] Optionally, the communication device 900 includes a communication line 902 and at least one communication interface 904. Since the memory 903, communication line 902, and communication interface 904 are all optional, they are all represented by dashed lines in Figure 9.

[0309] Optionally, the communication device 900 may further include a transceiver and / or an antenna. The transceiver can be used to send information to or receive information from other devices. The transceiver may be referred to as a transceiver unit, transceiver circuit, input / output interface, etc., and is used to realize the transmission and reception functions of the communication device 900 via the antenna. Optionally, the transceiver includes a transmitter and a receiver. For example, the transmitter can be used to generate a radio frequency (RF) signal from a baseband signal, and the receiver can be used to convert the RF signal back into a baseband signal.

[0310] The processor 901 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 programs according to the present application.

[0311] Communication line 902 may include a path for transmitting information between the aforementioned components.

[0312] Communication interface 904 uses any transceiver-like 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.

[0313] Memory 903 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory 903 may exist independently and be connected to processor 901 via communication line 902. Alternatively, memory 903 may be integrated with processor 901.

[0314] The memory 903 stores computer execution instructions for implementing the scheme of this application, and the processor 901 controls the execution of these instructions. The processor 901 executes the computer execution instructions stored in the memory 903 to implement the steps performed by the first UE, second UE, third UE, first IMS network element, second IMS network element, third IMS network element, or SMF as described in any of the embodiments shown in Figures 3, 4, 6, 7, or 8.

[0315] Optionally, the computer execution instructions in the embodiments of this application may also be referred to as application code, and the embodiments of this application do not specifically limit this.

[0316] In a specific implementation, as one example, processor 901 may include one or more CPUs, such as CPU0 and CPU1 in FIG9.

[0317] In a specific implementation, as one embodiment, the communication device 900 may include multiple processors, such as processors 901 and 905 in FIG. 9. Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. Here, a processor may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0318] When the device shown in Figure 9 is a chip, such as the chip of the first UE, the chip of the second UE, the chip of the third UE, the chip of the first IMS network element, the chip of the second IMS network element, the chip of the third IMS network element, or the chip of the SMF, then the chip includes a processor 901 (which may also include a processor 905), a communication line 902, and a communication interface 904. Optionally, it may include a memory 903. Specifically, the communication interface 904 may be an input interface, pins, or circuits, etc. The memory 903 may be a register, a cache, etc. The processor 901 and the processor 905 may be a general-purpose CPU, a microprocessor, an ASIC, or one or more integrated circuits for controlling the execution of a program that controls the communication method of any of the above embodiments.

[0319] This application embodiment can divide the device into functional modules according to the above method examples. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or software. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods. For example, when dividing each functional module according to each function, Figure 10 shows a schematic diagram of a device. The device 1000 can be the first UE, second UE, third UE, first IMS network element, second IMS network element, third IMS network element, or SMF involved in the above method embodiments, or it can be a chip in the first UE, second UE, third UE, SMF, first IMS network element, second IMS network element, or third IMS network element. The device 1000 includes a processing unit 1002 and a transceiver unit 1001.

[0320] It should be understood that the device 1000 can be used to implement the steps performed by the first UE, the second UE, the third UE, the first IMS network element, the second IMS network element, the third IMS network element, or the SMF in the communication method of the embodiments of this application. The relevant features can be referred to the embodiments shown in any one of the above figures 3, 4, 6, 7 or 8, and will not be repeated here.

[0321] Optionally, the functions / implementation processes of the transceiver unit 1001 and processing unit 1002 in Figure 10 can be implemented by the processor 901 in Figure 9 calling computer execution instructions stored in memory 903. Alternatively, the functions / implementation processes of the processing unit 1002 in Figure 10 can be implemented by the processor 901 in Figure 9 calling computer execution instructions stored in memory 903, and the functions / implementation processes of the transceiver unit 1001 in Figure 10 can be implemented by the communication interface 904 in Figure 9.

[0322] Optionally, when the device 1000 is a chip or circuit, the function / implementation process of the transceiver unit 1001 can also be implemented through pins or circuits, etc. Optionally, the transceiver unit 1001 may include a transmitting unit and / or a receiving unit, whereby the transmitting unit implements the transmitting function and the receiving unit implements the receiving function; or, the transceiver unit 1001 may be an integral module capable of implementing both transmitting and / or receiving functions. Optionally, the transceiver unit 1001 can be implemented using a transceiver.

[0323] This application also provides a computer-readable storage medium storing a computer program or instructions. When the computer program or instructions are executed, they implement the methods performed by the first UE, second UE, third UE, first IMS network element, second IMS network element, third IMS network element, or SMF in the aforementioned method embodiments. Thus, the functions described in the above embodiments can be implemented as software functional units and sold or used as independent products. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to it, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0324] This application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to perform the method executed by the first UE, the second UE, the third UE, the first IMS network element, the second IMS network element, the third IMS network element, or the SMF in any of the foregoing method embodiments.

[0325] This application also provides a processing device, including a processor and an interface; the processor is used to execute the method performed by the first UE, the second UE, the third UE, the first IMS network element, the second IMS network element, the third IMS network element, or the SMF involved in any of the above method embodiments.

[0326] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially 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, all or part of the processes or functions described in the embodiments of this application are generated. 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. 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 wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. 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 integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0327] The various illustrative logic units and circuits described in the embodiments of this application can be implemented or operate the described functions using a general-purpose processor, digital signal processor (DSP), ASIC, 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; alternatively, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented using a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0328] The steps of the methods or algorithms described in the embodiments of this application can be directly embedded in hardware, software units executed by a processor, or a combination of both. The software units can be stored in RAM, flash memory, ROM, erasable programmable read-only memory (EPROM), EEPROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and storage medium can be disposed in an ASIC, which can be disposed in the terminal device. Optionally, the processor and storage medium can also be disposed in different components of the terminal device.

[0329] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0330] The contents of the various embodiments of this application can be referenced to each other. Unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0331] It is understood that in the embodiments of this application, one or more network elements selected from the first UE, second UE, third UE, SMF, first IMS network element, second IMS network element, or third IMS network element may execute some or all of the steps in the embodiments of this application. These steps or operations are merely examples, and other operations or variations thereof may also be performed in the embodiments of this application. Furthermore, the steps may be performed in different orders as presented in the embodiments of this application, and it is not necessarily necessary to perform all the operations in the embodiments of this application.

Claims

1. A communication method, characterized in that, The method includes: The first Internet Protocol Multimedia Subsystem (IMS) network element receives a first call request from a first device, the first call request being used to request to perform a call service with a second device, the first device accessing the network via satellite; The first IMS network element determines that the first device uses a first encoding method to perform the call service, and the first encoding method corresponds to the satellite access method.

2. The method according to claim 1, characterized in that, The data transmission rate corresponding to the first encoding method is less than or equal to the first threshold.

3. The method according to claim 1 or 2, characterized in that, The network in question is a narrowband network.

4. The method according to any one of claims 1 to 3, characterized in that, The method further includes: Based on the first information included in the first call request, the first IMS network element determines that the first device accesses the network via satellite, and the first information is used to indicate the method by which the first device accesses the network; or... The first IMS network element receives a registration request from the first device, and determines, based on the second information included in the registration request, that the first device accesses the network via satellite, wherein the second information indicates the method by which the first device accesses the network; or... The first IMS network element receives fifth information from the third core network element, and determines that the first device accesses the network via satellite based on the fifth information. The fifth information is used to indicate the method by which the first device accesses the network.

5. The method according to claim 4, characterized in that, The first call request does not include information about the first encoding method.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: The first IMS network element sends a second call request to the second IMS network element serving the second device. The second call request includes information about the first encoding method, or includes information about the first encoding method and information about the second encoding method. The second encoding method is an encoding method supported by the first IMS network element.

7. The method according to claim 6, characterized in that, The method further includes: The first IMS network element receives a first response message from the second IMS network element, the first response message including information about the encoding methods supported by the second device; The first IMS network element determines the encoding method used by the call service between the second device and the IMS where the first IMS network element is located; The first IMS network element sends a first confirmation message to the second device. The first confirmation message is used to indicate the encoding method used by the call service between the second device and the IMS where the first IMS network element is located.

8. The method according to claim 7, characterized in that, The first response message includes third information, and the method further includes: The first IMS network element receives a second response message from the second IMS network element; The first IMS network element sends a third response message to the first device based on the second response message. The third response message includes the third information and also includes information about the first encoding method.

9. The method according to claim 7, characterized in that, The method further includes: The first IMS network element receives a first response message from the second IMS network element, the first response message including information about the encoding methods supported by the second device; The first IMS network element sends a third response message to the first device based on the first response message, and the third response message includes information about the first encoding method.

10. A communication method, characterized in that, The method includes: The call service is executed using a first encoding method, which corresponds to the satellite access method, wherein the first device accesses the network via satellite; A first call request is sent to a first IMS network element serving the first device via a service link. The first call request is used to request to perform a call service with the second device, and the first call request includes information about the first encoding method.

11. The method according to claim 10, characterized in that, The data transmission rate corresponding to the first encoding method is less than or equal to the first threshold.

12. The method according to claim 10 or 11, characterized in that, The network in question is a narrowband network.

13. The method according to any one of claims 10 to 12, characterized in that, The method further includes: A third response message is received, the third response message including third information, and the third response message also including information of the first encoding method.

14. A communication method, characterized in that, The method includes: The third call request is received from the second IMS network element through the service link. The third call request is used to request the execution of call service. The call service is determined to be executed using a first encoding method, which corresponds to the satellite access method. Send a fourth response message, which includes information about the first encoding method.

15. The method according to claim 14, characterized in that, After sending the fourth response message, the method further includes: In the absence of other messages, the first device performs the transmission of call data, which corresponds to the call service, and the other messages include messages other than the third call request.

16. The method according to claim 14, characterized in that, After sending the fourth response message, the method further includes: After receiving the first confirmation message, the system transmits call data with the first device, the call data corresponding to the call service.

17. The method according to any one of claims 14 to 16, characterized in that, The data transmission rate corresponding to the first encoding method is less than or equal to the first threshold.

18. A communication method, characterized in that, The method includes: Receive a second call request from a first IMS network element, the second call request including information of a first encoding method, or including information of a first encoding method and information of a second encoding method; When the second device accesses the network via satellite, a third call request is sent to the second device according to the second call request. The third call request includes information of the first encoding method but does not include information of the second encoding method.

19. The method according to claim 18, characterized in that, The data transmission rate corresponding to the first encoding method is less than or equal to the first threshold.

20. The method according to claim 18 or 19, characterized in that, The network in question is a narrowband network.

21. The method according to any one of claims 18 to 20, characterized in that, The method further includes: Upon receiving a registration request from the second device, and based on the fourth information included in the registration request, determining that the second device accesses the network via satellite; or, The system receives sixth information from the fourth core network element and determines, based on the sixth information, that the second device accesses the network via satellite.

22. A communication method, characterized in that, The method includes: Receive a first request message from a third device, the first request message being used to request registration or to request the establishment of a session; When the third device accesses the network via satellite, in response to the first request message, it sends first information, which is used to establish a first dedicated bearer, wherein the first dedicated bearer is used to transmit the call service of the third device, and the third device is the calling device or the called device of the call service.

23. The method according to claim 22, characterized in that, The network in question is a narrowband network.

24. The method according to claim 22 or 23, characterized in that, The first information is used to establish a first dedicated bearer, including: The first information is used to configure the first dedicated bearer; or, The first information is used to request the core network to configure the first dedicated bearer.

25. The method according to claim 24, characterized in that, The first information is also used to instruct the suspension of the first dedicated bearer.

26. The method according to any one of claims 22 to 25, characterized in that, The first request message is used to request the establishment of a session, and the method further includes: The device receives a second message, which instructs the third device to access the network via satellite.

27. The method according to any one of claims 22 to 26, characterized in that, The first request message is used to request the establishment of a session, and the method further includes: After the call service is initiated, the Quality of Service (QoS) parameters corresponding to the first dedicated bearer are received. Send an activation instruction, which is used to instruct the activation of the suspended first dedicated bearer.

28. The method according to any one of claims 22 to 25, characterized in that, The first request message is used to request registration. The first request message is also used to instruct the third device to access the network via satellite.

29. The method according to any one of claims 22-25, 28, characterized in that, The first request message is used to request registration, and the method further includes: After the call service is initiated, a response message is received from the called device of the call service, the response message being a response to the call request from the calling device of the call service; Send an activation instruction, which is used to instruct the activation of the suspended first dedicated bearer.

30. A communication method, characterized in that, The method includes: Send a first request message, which is used to request registration or to request the establishment of a session; Receive first information, the first information being used to configure a first dedicated bearer, and the first information also being used to instruct the suspension of the first dedicated bearer, wherein the first dedicated bearer is used to transmit call services.

31. The method according to claim 30, characterized in that, The method further includes: Send a first call request, the first call request being used to request to perform the call service with the second device; Activate the first dedicated bearer.

32. A communication method, characterized in that, The method includes: Receive a first call request from a first device, the first call request being used to request to perform a call service with a second device; Before receiving a response message from the second device, the first device or the second device sends a first request message to the core network element via the satellite access network. The first request message is used to request the configuration of a first dedicated bearer for transmitting the call service, and the response message is a response to the first call request.

33. The method according to claim 32, characterized in that, The network in question is a narrowband network.

34. The method according to claim 32 or 33, characterized in that, The method further includes: Based on the first information included in the first call request, it is determined that the first device accesses the network via satellite, wherein the first information indicates the method by which the first device accesses the network; or... Receive a registration request from the first device, and determine, based on the second information included in the registration request, that the first device accesses the network via satellite, wherein the second information indicates the method by which the first device accesses the network; or The system receives fifth information from a third core network element and determines, based on the fifth information, that the first device accesses the network via satellite. The fifth information is used to indicate the method by which the first device accesses the network.

35. The method according to any one of claims 32 to 34, characterized in that, The method further includes: Upon receiving a registration request from the second device, and based on the fourth information included in the registration request, determining that the second device accesses the network via satellite; or, The system receives sixth information from the fourth core network element and determines, based on the sixth information, that the second device accesses the network via satellite.

36. A communication method, characterized in that, The method includes: Receive a session establishment request from a third device; Based on the fact that the third device accesses the network via satellite, it is determined that the call service of the third device is transmitted through the default bearer, and the third device is the calling device or the called device of the call service. Send a first indication message to the third device, the first indication message being used to indicate that the call service is transmitted through the default bearer.

37. The method according to claim 36, characterized in that, The network in question is a narrowband network.

38. The method according to claim 36 or 37, characterized in that, The method further includes: After the call service is initiated, the QoS parameters of the call service are received; It is determined that the third device transmits the call service through the default bearer.

39. A communication method, characterized in that, The method includes: Send a session establishment request; Receive first indication information, which is used to indicate that the call service is transmitted through the default bearer.

40. The method according to claim 39, characterized in that, The third device connects to the network via satellite.

41. The method according to claim 39 or 40, characterized in that, The network in question is a narrowband network.

42. The method according to any one of claims 39 to 41, characterized in that, The third device is the calling device of the call service, and the method further includes: After receiving a response message from the called device in the call service, a call resource reservation success message is sent to the called device based on the first indication information.

43. The method according to any one of claims 39 to 41, characterized in that, The third device is the called device of the call service, and the method further includes: After receiving a successful call resource reservation message from the calling device of the call service, a successful call resource reservation response is sent to the calling device based on the first indication information.

44. A communication device, characterized in that, The communication device includes a processor and a memory, the memory for storing a computer program, and the processor for executing the computer program stored in the memory, causing the communication device to perform the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 13, or the method as described in any one of claims 14 to 17, or the method as described in any one of claims 18 to 21, or the method as described in any one of claims 22 to 29, or the method as described in any one of claims 30 to 31, or the method as described in any one of claims 32 to 35, or the method as described in any one of claims 36 to 38, or the method as described in any one of claims 39 to 43.

45. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program that, when run on a computer, causes the computer to perform the method as described in any one of claims 1 to 9, or causes the computer to perform the method as described in any one of claims 10 to 13, or causes the computer to perform the method as described in any one of claims 14 to 17, or causes the computer to perform the method as described in any one of claims 18 to 21, or causes the computer to perform the method as described in any one of claims 22 to 29, or causes the computer to perform the method as described in any one of claims 30 to 31, or causes the computer to perform the method as described in any one of claims 32 to 35, or causes the computer to perform the method as described in any one of claims 36 to 38, or causes the computer to perform the method as described in any one of claims 39 to 43.

46. ​​A computer program product, characterized in that, The computer program product includes a computer program that, when run on a computer, causes the computer to perform the method as described in any one of claims 1 to 9, or causes the computer to perform the method as described in any one of claims 10 to 13, or causes the computer to perform the method as described in any one of claims 14 to 17, or causes the computer to perform the method as described in any one of claims 18 to 21, or causes the computer to perform the method as described in any one of claims 22 to 29, or causes the computer to perform the method as described in any one of claims 30 to 31, or causes the computer to perform the method as described in any one of claims 32 to 35, or causes the computer to perform the method as described in any one of claims 36 to 38, or causes the computer to perform the method as described in any one of claims 39 to 43.

47. A chip system, characterized in that, The chip system includes: A processor and an interface, the processor being configured to invoke and execute instructions from the interface, wherein, when the processor executes the instructions, it implements the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 13, or the method as described in any one of claims 14 to 17, or the method as described in any one of claims 18 to 21, or the method as described in any one of claims 22 to 29, or the method as described in any one of claims 30 to 31, or the method as described in any one of claims 32 to 35, or the method as described in any one of claims 36 to 38, or the method as described in any one of claims 39 to 43.

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