Communication method and communication apparatus

Abstract

The present application provides a communication method and a communication apparatus. The method may comprise: a first network element (such as a P-CSCF network element in an IMS) in an IMS receives a first request message from a first terminal, wherein the first request message is used for requesting to establish a call with a second terminal; and the first network element in the IMS sends a second request message to an access gateway deployed on a satellite in a first network, so as to request a first access gateway to allocate transmission resources for transmitting media data between the first terminal and the second terminal, wherein the first terminal and the second terminal both access a network by means of the satellite. On this basis, the media data between the first terminal and the second terminal cannot pass through the ground, thereby shortening the time delay of satellite calls, and improving the user experience.

Description

Communication method and communication device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on January 12, 2024, with application number 202410054748.3, and priority to the Chinese patent application with the invention name “Communication Method and Communication Device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of wireless communications, and more particularly, to a communication method and a communication device. Background Art

[0003] Compared to terrestrial networks, satellite networks offer unique advantages. For example, they offer wider coverage, enabling communication services to areas beyond terrestrial coverage, such as oceans and forests. They are also less susceptible to natural disasters and external damage. Satellite communications have become a key feature of terminal devices, such as mobile phones, and making calls via satellite has become a fundamental requirement.

[0004] Currently, when a terminal device accesses a satellite network for a call, the call data must be routed through the terrestrial network. This not only increases latency and affects the user experience, but can also cause call interruptions if the terrestrial network experiences problems. Summary of the Invention

[0005] The present application provides a communication method and a communication device, which can enable call data to be exchanged directly on the satellite when a terminal device accesses the network via a satellite, without passing through the ground, thereby shortening the delay of satellite calls and improving the user experience.

[0006] In a first aspect, a communication method is provided, which can be performed by a device. The device can be a network element, or it can be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following is an example description using a network element as an example. The method may include: a first network element in an Internet Protocol Multimedia Subsystem IMS receives a first request message from a first terminal, where the first request message is used to request to establish a session with a second terminal; the first network element in the IMS sends a second request message to a first gateway in the IMS, where the second request message is used to request transmission resources, where the transmission resources are used to transmit media data between the first terminal and the second terminal, wherein the first gateway is deployed on a satellite, and the first terminal and the second terminal are both accessed via the satellite.

[0007] Optionally, the first network element is a session control network element in the IMS, or a functional module in the session control network element.

[0008] Based on the above technical solution, after receiving a request message from a first terminal accessed via a satellite, a first network element in the IMS (such as a session control network element in the IMS) can determine a gateway deployed on the satellite for the first terminal and request the gateway to allocate transmission resources for the first terminal's media data (or media data between the first terminal and the second terminal). In this way, the media data between the first terminal and the second terminal can be directly transmitted by the gateway deployed on the satellite, that is, the media data between the first terminal and the second terminal can be transmitted without passing through the ground (or without passing through the gateway on the ground). This shortens the latency of satellite calls and improves the user experience.

[0009] In combination with the first aspect, in certain implementations of the first aspect, the media data between the first terminal and the second terminal does not pass through a gateway deployed on the ground in the IMS.

[0010] In combination with the first aspect, in certain implementations of the first aspect, the first network element in the IMS sends a second request message to the first gateway in the IMS, including at least one of the following: when the first terminal is accessed via a satellite, the first network element in the IMS sends a second request message to the first gateway in the IMS; or, based on the subscription information of the first terminal or when the media data of the first terminal is allowed to not pass through a gateway deployed on the ground, the first network element in the IMS sends a second request message to the first gateway in the IMS, wherein the subscription information of the first terminal indicates that the media data of the first terminal is allowed to not pass through the ground and / or the first terminal is accessed via a satellite.

[0011] Based on the above technical solution, the first network element in the IMS can request the gateway deployed on the satellite to allocate transmission resources when it determines that certain conditions are met, thereby avoiding waste of resources.

[0012] In combination with the first aspect, in some implementations of the first aspect, the method further includes: the first network element in the IMS receives a registration request message from the first terminal, where the registration request message is used to request registration to the IMS; the first network element in the IMS sends the registration request message to the second network element in the IMS; and the first network element in the IMS receives a registration response message from the second network element in the IMS, where the registration response message includes subscription information of the first terminal.

[0013] Based on the above technical solution, the first network element in the IMS can obtain the contract information of the terminal during the terminal registration process (ie, registering with the IMS), and then directly read the contract information when using it, thereby reducing call delay.

[0014] In combination with the first aspect, in some implementations of the first aspect, the method further includes: the first network element in the IMS receives a first response message, where the first response message indicates that media data between the first terminal and the second terminal does not pass through a gateway deployed on the ground.

[0015] Optionally, the first network element in the IMS receives the first response message from the second terminal side. As an example, the second terminal side includes at least one of the following: the second terminal, a network element of the network where the second terminal is located (such as a P-CSCF network element, an S-CSCF network element, etc.), which is not limited to this.

[0016] In combination with the first aspect, in certain implementations of the first aspect, the method further includes: the first network element in the IMS sends a third request message to the second gateway in the IMS, the third request message being used to request transmission resources, the transmission resources being used to transmit media data between the first terminal and the second terminal, and the second gateway being deployed on the ground.

[0017] In combination with the first aspect, in some implementations of the first aspect, the method further includes: releasing the second gateway according to the first response message.

[0018] Based on the above technical solution, after receiving the first request message from the first terminal, the first network element in the IMS can also determine a gateway deployed on the ground for the first terminal. If the first terminal and the second terminal cannot communicate through the gateway deployed on the satellite, they can directly use the access network element on the ground to communicate, thereby reducing latency.

[0019] In combination with the first aspect, in certain implementations of the first aspect, at least one network element in the IMS is deployed in a visited network, the at least one network element includes the first network element and a border control network element, and at least one third network element in the IMS is deployed in a home network. The method also includes: the first network element in the IMS sends the first request message to the border control network element, requesting the border control network element to determine a gateway deployed on the ground for the first terminal.

[0020] The visited network is the visited network of the first terminal, and the home network is the home network of the first terminal.

[0021] In combination with the first aspect, in certain implementations of the first aspect, at least one network element in the IMS is deployed in a visited network, the at least one network element includes the first network element, and at least one third network element in the IMS is deployed in a home network. The method also includes: the first network element in the IMS sends a first indication message to a network element in the at least one third network element, and the first indication message indicates that the media data between the first terminal and the second terminal performs visited network routing.

[0022] Optionally, the first network element in the IMS sends the first indication information to the network element in the home network of the first terminal through other network elements (such as other network elements in the IMS).

[0023] In combination with the first aspect, in certain implementations of the first aspect, the method further includes: the first network element in the IMS sends second indication information to the network element in the first network, wherein the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground.

[0024] Based on the above technical solution, media data between the first terminal and the second terminal can be exchanged on the satellite through the configuration of the core network.

[0025] In combination with the first aspect, in certain implementations of the first aspect, the first network element in the IMS sends second indication information to the network element in the first network, including at least one of the following: when the first terminal is accessed via a satellite, the first network element in the IMS sends the second indication information to the network element in the first network; or, based on the subscription information of the first terminal or when the media data of the first terminal is allowed to not pass through a gateway deployed on the ground, the first network element in the IMS sends the second indication information to the network element in the first network, wherein the subscription information of the first terminal indicates that the media data of the first terminal is allowed to not pass through the ground and / or the first terminal is accessed via a satellite; or, when the first terminal and the second terminal are served by the same policy control network element and / or session control network element, the first network element in the IMS sends the second indication information to the network element in the first network.

[0026] Optionally, the network element in the first network is a core network element.

[0027] Based on the above technical solution, the first network element in the IMS can send second indication information to the network element in the first network when certain conditions are met. When it is determined that the same first terminal and the second terminal are served by the same policy control network element and / or session control network element, the second indication information is sent to the network element in the first network. This can increase the possibility that the network element in the first network can successfully configure the exchange of media data between the first terminal and the second terminal on the satellite.

[0028] In combination with the first aspect, in certain implementations of the first aspect, the first terminal and the second terminal satisfy any one of the following: the first terminal and the second terminal are served by the same satellite; or, the first terminal and the second terminal are served by different satellites, and there is an inter-satellite link between the different satellites.

[0029] In combination with the first aspect, in some implementations of the first aspect, the method further includes: when the media data between the first terminal and the second terminal is transmitted by the first gateway, sending a second response message to the first terminal, the second response message including the address of the first gateway.

[0030] In combination with the first aspect, in some implementations of the first aspect, the first network element in the IMS is deployed on a satellite.

[0031] In combination with the first aspect, in some implementations of the first aspect, the IMS is an Internet Protocol Multimedia Subsystem IMS; and / or the first network element in the IMS is a session control network element in the IMS.

[0032] In a second aspect, a communication method is provided, which can be performed by a device. The device can be a network element, or it can be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following is an example of an example of a network element. The method may include: a first network element in a second network receives a first request message from a first terminal through the first network, and the first request message is used to request to establish a session with the second terminal; the first network element in the second network sends a second request message to a first gateway in the second network, and the second request message is used to request transmission resources, and the transmission resources are used to transmit media data between the first terminal and the second terminal, wherein the first gateway is deployed on a satellite, and the first terminal and the second terminal are both accessed through the satellite.

[0033] Optionally, the second network is a network that provides services to the terminal, such as providing multimedia services to the terminal. As an example, the second network is an Internet Protocol (IP) Multimedia Subsystem (IMS). Further optionally, the first network element is a network element in the IMS, such as a session control network element in the IMS, or a functional module in the session control network element.

[0034] Optionally, the first network is used to establish a connection between the second network (such as IMS) and the terminal, that is, to enable the terminal to communicate with the second network.

[0035] Optionally, the first network is an IP connectivity access network (IP-CAN). As an example, the first network is an evolved packet system (EPS) or a 5G system (5th generation system, 5GS).

[0036] In combination with the second aspect, in certain implementations of the second aspect, the media data between the first terminal and the second terminal does not pass through a gateway deployed on the ground in the second network.

[0037] In combination with the second aspect, in certain implementations of the second aspect, the first network element in the second network sends a second request message to the first gateway in the second network, including at least one of the following: when the first terminal is accessed via satellite, the first network element in the second network sends a second request message to the first gateway in the second network; or, based on the contract information of the first terminal or when the media data of the first terminal is allowed to not pass through a gateway deployed on the ground, the first network element in the second network sends a second request message to the first gateway in the second network, wherein the contract information of the first terminal indicates that the media data of the first terminal is allowed to not pass through the ground and / or the first terminal is accessed via satellite.

[0038] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: the first network element in the second network receives a registration request message from the first terminal through the first network, and the registration request message is used to request registration to the second network; the first network element in the second network sends the registration request message to the second network element in the second network; the first network element in the second network receives a registration response message from the second network element in the second network, and the registration response message includes the subscription information of the first terminal.

[0039] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: a first network element in the second network receives a first response message, and the first response message indicates that the media data between the first terminal and the second terminal does not pass through a gateway deployed on the ground.

[0040] Optionally, the first network element in the second network receives a first response message from the second terminal side.

[0041] In combination with the second aspect, in certain implementations of the second aspect, the method also includes: the first network element in the second network sends a third request message to the second gateway in the second network, the third request message is used to request transmission resources, the transmission resources are used to transmit media data between the first terminal and the second terminal, and the second gateway is deployed on the ground.

[0042] In combination with the second aspect, in some implementations of the second aspect, the method further includes: releasing the second gateway while allowing media data between the first terminal and the second terminal to not pass through the second gateway.

[0043] In combination with the second aspect, in certain implementations of the second aspect, at least one network element in the second network is deployed in a visited network, the at least one network element includes the first network element and a border control network element, and at least one third network element in the second network is deployed in a home network. The method also includes: the first network element in the second network sends the first request message to the border control network element, requesting the border control network element to determine a gateway deployed on the ground for the first terminal.

[0044] In combination with the second aspect, in certain implementations of the second aspect, at least one network element in the second network is deployed in a visited network, the at least one network element includes the first network element, and at least one third network element in the second network is deployed in a home network. The method also includes: the first network element in the second network sends first indication information to a network element in the at least one third network element, and the first indication information indicates that the media data between the first terminal and the second terminal performs visited network routing.

[0045] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: the first network element in the second network sends second indication information to the first network, and the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground.

[0046] Optionally, the first network element in the second network sends second indication information to the first network element in the first network.

[0047] In combination with the second aspect, in certain implementations of the second aspect, the first network element in the second network sends second indication information to the first network, including at least one of the following: when the first terminal is accessed via a satellite, the first network element in the second network sends the second indication information to the first network; or, based on the contract information of the first terminal or when the media data of the first terminal is allowed to not pass through a gateway deployed on the ground, the first network element in the second network sends the second indication information to the first network, wherein the contract information of the first terminal indicates that the media data of the first terminal is allowed to not pass through the ground and / or the first terminal is accessed via a satellite; or, when the first terminal and the second terminal are served by the same policy control network element and / or session control network element, the first network element in the second network sends the second indication information to the first network.

[0048] In combination with the second aspect, in certain implementations of the second aspect, the first terminal and the second terminal satisfy any one of the following: the first terminal and the second terminal are served by the same satellite; or, the first terminal and the second terminal are served by different satellites, and there is an inter-satellite link between the different satellites.

[0049] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: when the media data between the first terminal and the second terminal is transmitted by the first gateway, the first network element in the second network sends a second response message to the first terminal through the first network, and the second response message includes the address of the first gateway.

[0050] In combination with the second aspect, in some implementations of the second aspect, the first network element in the second network is deployed on a satellite.

[0051] In combination with the second aspect, in some implementations of the second aspect, the second network is an Internet Protocol Multimedia Subsystem IMS; and / or the first network element in the second network is a session control network element in the IMS.

[0052] According to a third aspect, a communication method is provided, which can be performed by a device. The device can be a network element, or it can be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following is an example of an example of a network element in a first network. The method may include: the network element in the first network receives second indication information from the network element in the second network, and the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground; the network element in the first network sends a response message to the network element in the second network, and the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the satellite, or the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the ground.

[0053] For the first network, please refer to the relevant description in the second aspect and will not be repeated here.

[0054] In combination with the third aspect, in certain implementations of the third aspect, both the first terminal and the second terminal are accessed via a satellite.

[0055] In combination with the third aspect, in certain implementations of the third aspect, when the first terminal and the second terminal are served by the same policy control network element, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the satellite; or, when the first terminal and the second terminal are served by the same user-plane network element, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the satellite; or, when there is an inter-satellite link between the first terminal and the second terminal, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the satellite.

[0056] In a fourth aspect, a communication method is provided, which can be executed by an apparatus. The apparatus may be a network element, or may be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following is an example of an explanation using a network element. The method may include: a first network element in an IMS receives a first request message from a first terminal, wherein the first request message is used to request establishment of a session with a second terminal; the first network element in the IMS sends a second request message to a first gateway, wherein the second request message is used to request transmission resources, and the transmission resources are used to transmit media data between the first terminal device and the second terminal device, wherein the first gateway is deployed on a satellite, and the first terminal and the second terminal are both accessed via a satellite; in response to the second request message, the first gateway allocates the transmission resources for the media data between the first terminal device and the second terminal device.

[0057] For relevant solutions regarding the first network element in the IMS, reference may be made to the relevant description in the first aspect.

[0058] In a fifth aspect, a communication method is provided, which can be performed by an apparatus. The apparatus may be a network element, or may be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following is an example of an explanation taking a network element as an example. The method may include: a first network element in a second network receives a first request message from a first terminal through the first network, wherein the first request message is used to request to establish a session with the second terminal; the first network element in the second network sends a second request message to a first gateway, wherein the second request message is used to request transmission resources, and the transmission resources are used to transmit media data between the first terminal device and the second terminal device, wherein the first gateway is deployed on a satellite, and the first terminal and the second terminal are both accessed through the satellite; in response to the second request message, the first gateway allocates the transmission resources for the media data between the first terminal device and the second terminal device.

[0059] For relevant solutions regarding the first network element in the second network, reference may be made to the relevant description in the second aspect.

[0060] In a sixth aspect, a communication method is provided, which can be performed by a device. The device can be a gateway, or it can be a component of a gateway (such as a chip or a chip system or a circuit), which is not limited in this application. The following example is illustrated using a gateway as an example. The method may include: a first gateway in an IMS receives media data from a first terminal; the first gateway in the IMS sends the media data to a second terminal via an intersatellite link; wherein the first gateway is deployed on a satellite, and the first terminal and the second terminal are both accessed via a satellite.

[0061] In combination with the sixth aspect, in certain implementations of the sixth aspect, before the first gateway in the IMS receives media data from the first terminal, the method further includes: the first gateway in the IMS receives a second request message from the first network element in the IMS, the second request message being used to request transmission resources, and the transmission resources being used to transmit media data between the first terminal device and the second terminal device.

[0062] In a seventh aspect, a communication method is provided, which can be performed by a device. The device can be a network element, or it can be a component of a network element (such as a chip or a chip system or a circuit), which is not limited in this application. The following example is illustrated using a network element in a home network. The method may include: receiving a session call message from a first terminal; determining whether media data between the first terminal and the second terminal performs visited network routing or loopback; wherein the first terminal and the second terminal are both accessed via satellite.

[0063] In combination with the seventh aspect, in certain implementations of the seventh aspect, the media data between the first terminal and the second terminal passes through a first gateway and does not pass through the ground, and the first gateway is deployed on a satellite.

[0064] In combination with the seventh aspect, in certain implementations of the seventh aspect, the determination of whether the media data between the first terminal and the second terminal executes visited network routing or loopback includes: determining, based on the contract information of the first terminal, that the media data between the first terminal and the second terminal executes visited network routing or loopback; and / or receiving indication information from a network element in the visited network, and determining, based on the indication information, that the media data between the first terminal and the second terminal executes visited network routing or loopback.

[0065] In an eighth aspect, a device is provided, which is deployed on a satellite. The device includes a first gateway in an IMS, the first gateway is deployed on the satellite, and the first gateway is used to transmit media data between terminals accessed via the satellite.

[0066] Among them, the first gateway can refer to the relevant description in the first aspect or the sixth aspect.

[0067] In combination with the eighth aspect, in some implementations of the eighth aspect, the apparatus further includes a first network element in the IMS, and the first network element in the IMS communicates with the first gateway.

[0068] For the first network element in the IMS, reference may be made to the relevant description in the first aspect.

[0069] In combination with the eighth aspect, in certain implementations of the eighth aspect, the device also includes a user plane network element in the first network, or the device also includes: a user plane network element in the first network and an access network network element in the first network; wherein, the terminal communicates with the first network through the user plane network element and / or the access network element. Exemplarily, the terminal sends registration information to the first network through the user plane network element or the access network element, and the registration information can be sent to the second network (such as an IMS network) through other network elements in the first network. The first network can be a 4G or 5G communication network.

[0070] Regarding the second to eighth aspects, reference may be made to the description of the first aspect, such as the description of the various implementation methods and corresponding technical effects in the first aspect, which will not be repeated here.

[0071] In a ninth aspect, a communication device is provided, the device being configured to execute the method of any possible implementation of aspects 1 to 8. Specifically, the device may include units and / or modules, such as a processing unit and / or a communication unit, for executing the method of any possible implementation of aspects 1 to 8.

[0072] In one implementation, the apparatus is a communications device (e.g., a first network element, a first gateway, or a core network element). When the apparatus is a communications device, the communications unit may be a transceiver or an input / output interface; the processing unit may be at least one processor. Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0073] In another implementation, the apparatus is a chip, chip system, or circuit for a communication device (e.g., a first network element, a first gateway, or a core network element). When the apparatus is a chip, chip system, or circuit for a communication device, the communication unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip, chip system, or circuit; and the processing unit may be at least one processor, processing circuit, or logic circuit.

[0074] In a tenth aspect, a communication device is provided, comprising: at least one processor configured to execute a computer program or instructions stored in a memory to perform the method of any possible implementation of aspects 1 to 8. Optionally, the device further comprises a memory configured to store the computer program or instructions. Optionally, the device further comprises a communication interface, and the processor reads the computer program or instructions in the memory through the communication interface.

[0075] In one implementation, the apparatus is a communication device (such as a first network element, a first gateway, or a core network element).

[0076] In another implementation, the device is a chip, a chip system, or a circuit used in a communication device (such as a first network element, a first gateway, or a core network element).

[0077] In the eleventh aspect, a processor is provided for executing the methods provided in the first to eighth aspects above.

[0078] For the operations such as sending and acquiring / receiving involved in the processor, unless otherwise specified, or if they do not conflict with their actual functions or internal logic in the relevant descriptions, they can be understood as processor output, reception, input and other operations, and can also be understood as sending and receiving operations performed by the radio frequency circuit and antenna. This application does not limit this.

[0079] Optionally, the device further includes: a memory for storing programs; accordingly, at least one processor is used to execute computer programs or instructions in the memory.

[0080] Optionally, the device further includes a communication interface, which is coupled to the processor and can be used to input information to the processor or output information from the processor.

[0081] In a twelfth aspect, a computer-readable storage medium is provided, which stores a program code for execution by a device, and the program code includes a method for executing any possible implementation of the above-mentioned first to eighth aspects.

[0082] In a thirteenth aspect, a computer program product comprising instructions is provided, which, when run on a computer, enables the computer to execute the method in any possible implementation of the first to eighth aspects above.

[0083] In the fourteenth aspect, a chip is provided, which includes a processor and a communication interface. The processor reads instructions on the memory through the communication interface and executes the method provided by any of the above-mentioned implementation methods of any of the above-mentioned aspects from the first to the eighth aspects.

[0084] Optionally, as an implementation method, the chip also includes a memory, in which a computer program or instruction is stored, and the processor is used to execute the computer program or instruction on the memory. When the computer program or instruction is executed, the processor is used to execute the method provided in any one of the above-mentioned implementation methods of any one of the first to eighth aspects.

[0085] In a fifteenth aspect, a computer program product comprising instructions is provided, which, when run on a computer, enables the computer to execute the method provided by any one of the above-mentioned implementations of the first aspect.

[0086] In the sixteenth aspect, a communication system is provided, comprising at least one of the aforementioned first network element, first gateway, network element in the first network, user plane network element in the first network and / or access network network element. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] FIG1 is a schematic diagram of a network architecture applicable to an embodiment of the present application.

[0088] FIG2 is a schematic diagram of another network architecture applicable to an embodiment of the present application.

[0089] (a)-(c) in FIG3 are schematic diagrams of another network architecture applicable to an embodiment of the present application.

[0090] (a)-(d) in FIG4 are schematic diagrams of a network architecture proposed according to an embodiment of the present application.

[0091] FIG5 is a schematic diagram of a communication method 500 provided in an embodiment of the present application.

[0092] FIG6 is a schematic diagram of a UE performing IMS registration applicable to an embodiment of the present application.

[0093] FIG. 7 is another schematic diagram of a UE performing IMS registration applicable to an embodiment of the present application.

[0094] FIG8 is a schematic diagram of a communication method 800 provided in an embodiment of the present application.

[0095] FIG9 is a schematic flowchart of a communication method 900 applicable to an embodiment of the present application.

[0096] FIG10 is a schematic flowchart of a communication method 1000 applicable to an embodiment of the present application.

[0097] FIG11 is a schematic flowchart of a communication method 1100 applicable to an embodiment of the present application.

[0098] FIG12 is a schematic flowchart of a communication method 1200 applicable to an embodiment of the present application.

[0099] FIG13 is a schematic flowchart of a communication method 1300 applicable to an embodiment of the present application.

[0100] FIG14 is a schematic diagram of an optimal media routing (OMR) mechanism applicable to an embodiment of the present application.

[0101] FIG15 is a schematic diagram of a communication device 1500 provided in an embodiment of the present application.

[0102] FIG16 is a schematic diagram of another communication device 1600 provided in an embodiment of the present application.

[0103] FIG17 is a schematic diagram of a chip system 1700 provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0104] The technical solution in this application will be described below with reference to the accompanying drawings.

[0105] The technical solution provided in this application can be applied to non-terrestrial network (NTN) systems such as intersatellite communication and satellite communication. As an example, a satellite communication system includes a satellite base station and a terminal device. The satellite base station provides communication services for the terminal device. The satellite base station can also communicate with other base stations. A satellite can serve as a base station or as a terminal device. Among them, a satellite can refer to a drone, a hot air balloon, a low-orbit satellite, a medium-orbit satellite, a high-orbit satellite, etc. A satellite can also refer to a non-ground base station or non-ground equipment, etc.

[0106] The technical solutions provided in this application can also be applied to various communication systems, such as: fifth generation (5G) or new radio (NR) systems, long term evolution (LTE) systems, etc. The technical solutions provided in this application can also be applied to future communication systems. The technical solutions provided in this application can also be applied to device to device (D2D) communication, vehicle to everything (V2X) communication, machine to machine (M2M) communication, machine type communication (MTC), and Internet of Things (IoT) communication systems. Among them, V2X can include: vehicle to vehicle (V2V) communication, vehicle to infrastructure (V2I) communication, vehicle to pedestrian (V2P) communication or vehicle to network (V2N) communication, etc.

[0107] A device in a communication system can send or receive signals to or from another device. The signals may include information, signaling, or data. The term "device" may also be replaced by an entity, network entity, network element, gateway, communication device, communication module, node, communication node, and the like.

[0108] Below, the network architecture applicable to the embodiments of the present application is introduced in conjunction with Figures 1 to 4.

[0109] Refer to FIG1 , which is a schematic diagram of a network architecture applicable to an embodiment of the present application.

[0110] As shown in Figure 1, the network architecture takes the 5G system (5GS) as an example. The network architecture can be divided into two parts: the access network and the core network. The network architecture may include but is not limited to: unified data management (UDM), network exposure function (NEF), network repository function (NRF), policy control function (PCF), application function (AF), access and mobility management function (AMF), session management function (SMF), user equipment (UE), radio access network equipment, UPF, and data network (DN). Among them, DN can be the Internet; UDM, NEF, NRF, PCF, AF, AMF, SMF, and UPF are network elements in the core network. Since Figure 1 takes the 5G system as an example, the core network can be called the 5G core network (5GC or 5GCN).

[0111] The following is a brief introduction to each network element.

[0112] 1. UE: can be referred to as terminal equipment, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The following description uses terminal equipment as an example.

[0113] Terminal devices include various devices with wireless communication functions, which can be used to connect people, objects, machines, etc. Terminal devices can be widely used in various scenarios, such as: cellular communication, D2D, V2X, peer to peer (P2P), M2M, MTC, IoT, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery, etc. Terminal devices can be terminals in any of the above scenarios, such as MTC terminals, IoT terminals, etc. Terminal devices can be 3GPP (3rd Generation Partnership Project) terminals. rdThe present invention relates to user equipment (UE), terminal, fixed device, mobile station device or mobile device, subscriber unit, handheld device, vehicle-mounted device, wearable device, cellular phone, smart phone, Session Initiation Protocol (SIP) phone, wireless data card, personal digital assistant (PDA), computer, tablet computer, notebook computer, wireless modem, handheld device, laptop computer, computer with wireless transceiver function, smart book, vehicle, satellite, global positioning system (GPS) device, target tracking device, aircraft (such as drone, helicopter, multi-copter, quadcopter, or airplane), ship, remote control device, smart home device, industrial equipment, or device built into the above devices (such as communication module, modem or chip in the above devices), or other processing devices connected to the wireless modem. For the convenience of description, the terminal device will be described below by taking the terminal or UE as an example.

[0114] It should be understood that in some scenarios, a UE can also be used to act as a base station. For example, a UE can act as a scheduling entity that provides sidelink signals between UEs in scenarios such as V2X, D2D, or P2P.

[0115] In the embodiments of the present application, the device for implementing the function of the terminal device, i.e., the terminal device, can be the terminal device, or a device capable of supporting the terminal device to implement the function, such as a chip system or chip, which can be installed in the terminal device. In the embodiments of the present application, the chip system can be composed of a chip, or can include a chip and other discrete devices.

[0116] The terminal device can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; it can also be deployed on the water surface; it can also be deployed on aircraft, balloons and satellites in the air. The embodiments of this application do not limit the scenario in which the terminal device is located. In addition, the terminal device can be a hardware device, or it can be a software function running on dedicated hardware, a software function running on general-purpose hardware, such as a virtualization function instantiated on a platform (for example, a cloud platform), or an entity including dedicated or general-purpose hardware devices and software functions. This application does not limit the specific form of the terminal device.

[0117] 2. (Radio) access network (R)AN): provides access to the communication network for authorized users in a specific area. It can include wireless network equipment in the 3rd Generation Partnership Project (3GPP) network and access points in non-3GPP networks.

[0118] The RAN manages radio resources, provides access services to user devices, and forwards control signals and user device data between the user device and the core network. The RAN can also be understood as a base station in a traditional network.

[0119] Exemplarily, the access network device in the embodiment of the present application can be any communication device with wireless transceiver functions for communicating with a user equipment. The access network device includes but is not limited to: an evolved Node B (eNB), a baseband unit (BBU), an access point (AP) in a wireless fidelity (WIFI) system, a wireless relay node, a wireless backhaul node, a transmission point (TP) or a transmission and reception point (TRP), etc., and can also be a gNB in ​​a 5G, such as NR, system, or a transmission point (TRP or TP), one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system, or a network node constituting a gNB or a transmission point, such as a baseband unit (BBU) or a distributed unit (DU), etc.

[0120] In some deployments, a gNB may include a centralized unit (CU) and a DU. The gNB may also include an active antenna unit (AAU). The CU implements some gNB functions, while the DU implements some gNB functions. For example, the CU is responsible for processing non-real-time protocols and services, implementing the functions of the radio resource control (RRC) and packet data convergence protocol (PDCP) layers. The DU is responsible for processing physical layer protocols and real-time services, implementing the functions of the radio link control (RLC), media access control (MAC), and physical (PHY) layers. The AAU implements some physical layer processing functions, RF processing, and active antenna-related functions. Because RRC layer information ultimately becomes PHY layer information, or is converted from PHY layer information, in this architecture, higher-layer signaling, such as RRC layer signaling, can also be considered to be sent by the DU, or by both the DU and the AAU. It is understood that an access network device can be a device that includes one or more of a CU node, a DU node, or an AAU node. In addition, the CU may be classified as an access network device in an access network (radio access network, RAN), or the CU may be classified as an access network device in a core network (core network, CN), which is not limited in this application.

[0121] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (O-RAN) system, CU may also be referred to as an open-central unit (O-CU); DU may also be referred to as an open-distributed unit (O-DU); CU-CP may also be referred to as O-CU-CP, CU-UP may also be referred to as O-CU-UP, and RU may also be referred to as O-RU. For the sake of convenience of description, this application uses CU, CU-CP, CU-UP, DU and RU as examples for description. Any of the CU (or CU-CP, CU-UP), DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0122] In the embodiments of the present application, the apparatus for implementing the RAN function may be a device, or a device capable of supporting the device in implementing the function, such as a system-on-chip (SoC) or a chip, which may be installed in the device. In the embodiments of the present application, the SoC may be composed of a chip, or may include a chip and other discrete components. The embodiments of the present application are described using the device as an example, and do not limit the embodiments of the present application.

[0123] RAN can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; it can also be deployed on the water surface; it can also be deployed on aircraft, balloons and satellites in the air. The embodiments of this application do not limit the scenario in which the RAN is located. In addition, the RAN can be a hardware device, or it can be a software function running on dedicated hardware, a software function running on general-purpose hardware, such as a virtualized function instantiated on a platform (e.g., a cloud platform), or an entity including dedicated or general-purpose hardware devices and software functions. This application does not limit the specific form of the RAN.

[0124] 3. UPF network element: This element is used for packet routing and forwarding, as well as quality of service (QoS) processing for user plane data. User data can be connected to the data network (DN) through this element. In the embodiments of the present application, it can be used to implement the functions of the user plane network element.

[0125] 4. Data network (DN): A network used to transmit data, such as operator service networks (such as the IP multimedia subsystem (IMS)), the Internet, and third-party service networks.

[0126] 5. Operations, administration and management (OAM) network element: Mainly used for network and service analysis, forecasting, planning and configuration, as well as testing and fault management of the network and its services.

[0127] 6. Access and mobility management function (AMF) network element: It is mainly used for mobility management and access management. It can be used to implement other functions of the mobility management entity (MME) in addition to session management, such as access authorization / authentication.

[0128] 7. Session management function (SMF) network element: mainly used for session management, network Internet protocol (IP) address allocation and management of terminal devices, selection and management of user plane functions, policy control and billing function interface endpoints, and downlink data notification.

[0129] 8. Policy control function (PCF) network element: A unified policy framework used to guide network behavior, providing policy rule information to network elements (such as AMF, SMF network elements, etc.) or terminal devices.

[0130] 9. Network repository function (NRF) network element: used to store descriptions of network function entities and the services they provide, and to support functions such as service discovery and network element entity discovery.

[0131] 10. Network exposure function (NEF) network element: used to securely expose services and capabilities provided by the Third Generation Partnership Project (3GPP) network function to the outside world.

[0132] 11. Unified data management (UDM) network element: used for unified data management, 5G user data management, processing user identification, access authentication, registration, or mobility management, etc.

[0133] 12. Application function (AF) network element: used for data routing affected by applications, accessing network open function network elements, and interacting with the policy framework for policy control.

[0134] 13. Network data analytics function (NWDAF) network element: NWDAF has data collection, training, analysis, and reasoning functions. It can be used to collect relevant data from network elements, third-party service servers, terminal devices, or network management systems, perform analysis and training based on the relevant data, and provide data analysis results to network elements, third-party service servers, terminal devices, or network management systems. The analysis results can assist the network in selecting service quality parameters, assist the network in executing traffic routing, or assist the network in selecting background data transmission strategies.

[0135] In the embodiment of the present application, the NWDAF may be a separate network element or may be co-located with other network elements. For example, the NWDAF network element may be co-located with the AMF or with the SMF.

[0136] It can be understood that the network elements included in the communication system listed above are only exemplary illustrations and the present application is not limited thereto.

[0137] In the above network architecture, the N2 interface is the interface between the RAN and AMF network elements, used for transmitting radio parameters and non-access stratum (NAS) signaling; the N3 interface is the interface between the RAN and UPF network elements, used for transmitting user plane data; the N4 interface is the interface between the SMF network element and the UPF network element, used for transmitting information such as service policies, tunnel identification information for N3 connections, data cache indication information, and downlink data notification messages. The N6 interface is the interface between the DN network element and the UPF network element, used for transmitting user plane data. It can be understood that in the above network architecture, network elements can also exchange information through service-based interfaces (such as Namf, Nsmf, Nnwdaf, etc.).

[0138] See FIG. 2 , which is a schematic diagram of another network architecture applicable to an embodiment of the present application.

[0139] As shown in Figure 2, the network architecture uses the NTN as an example. By way of example, the network architecture may include: a ground station (gateway, GW), a satellite, terminal devices, a ground network, etc. To distinguish it from a terrestrial communication system, the gateway is referred to here as a ground station. A ground station can provide functions similar to gateways in terrestrial communication systems, such as establishing connections with terminal devices and communicating with servers. A ground station also has functions such as satellite monitoring, fault detection, packet switching of communication data, and interface protocol conversion. By way of example, the link between the ground station and the satellite is called a feeder link, and the link between the satellite and the terminal device is called a service link.

[0140] See FIG3 , which is a schematic diagram of another network architecture applicable to an embodiment of the present application.

[0141] Before introducing Figure 3, let's first explain roaming. Taking carrier A and carrier B as an example, roaming refers to a situation where a mobile user belonging to carrier A accesses carrier B's network. For this user, carrier A's network is considered the home network (or home network), and carrier B's network is considered the visited network.

[0142] A cellular mobile communication network of a certain type and operating under a certain operator is called a public land mobile network (PLMN). The PLMN (i.e., home network) to which a user subscribes is called the home PLMN (HPLMN), and the PLMN to which a user roams (i.e., visited network) is called the visited PLMN (VPLMN).

[0143] For example, roaming scenarios can be divided into local breakout (LBO) roaming and home routed (HR) roaming. The difference between the two lies in whether the session (such as the protocol data unit (PDU) session) is connected to the user plane function (UPF) of the home network. For example, in the HR roaming scenario, the session is connected to the UPF of the home network; in the LBO roaming scenario, the session is not connected to the UPF of the home network. For details about HR roaming and LBO roaming, please refer to the relevant descriptions in the protocol and are not limited to them.

[0144] As shown in Figure 3, the network architecture uses LBO roaming in the IMS architecture as an example. This network architecture may include, but is not limited to: a proxy-call session control function (P-CSCF) network element, a serving-call session control function (S-CSCF) network element, an interconnection border control function (IBCF) network element, a policy and charging rules function (PCRF), a transition gateway (TrGW) network element, a multimedia resource function processor (MRFP), and an IMS-access gateway (IMS-AGW). The following mainly introduces the P-CSCF network element and the S-CSCF network element.

[0145] 1. P-CSCF network element: This is the entry point (or first access point) for terminal devices to access the IMS network. It is primarily responsible for forwarding Session Initiation Protocol (SIP) signaling between the terminal device and the home or visited network. The P-CSCF network element acts like a proxy, accepting requests and servicing them internally or forwarding them upstream.

[0146] The P-CSCF network element may be located in a visited network, as shown in (a) or (c) of FIG3 ; the P-CSCF network element may also be located in a home network, as shown in (b) of FIG3 .

[0147] 2. S-CSCF network element: This is the central node of the IMS network, primarily performing session control services for terminal devices. The S-CSCF network element maintains session state to support services as required by the network operator.

[0148] The S-CSCF network element may be located in the home network, as shown in (a) to (c) of FIG. 3 .

[0149] Regarding the IMS architecture, the above is only an example and is not limiting. Other forms of IMS architecture can also be applied to the embodiments of the present application. For a detailed description of the IMS architecture, reference can be made to the IMS architecture involved in protocol TS23.228.

[0150] In addition, FIG3 above illustrates a roaming scenario as an example, but is not limited thereto. The embodiments of the present application can also be applied to a non-roaming scenario, which is similar to FIG3 , except that the evolved packet system (EPS) / 5GS is located within the HPLMN and there is no visited PCRF (V-PCRF) network element or visited PCF (V-PCF) network element.

[0151] The above-mentioned Figures 1 to 3 are merely schematic diagrams, and the system architecture applicable to the embodiments of the present application is not limited thereto.

[0152] When a terminal device accesses the network via satellite for call services, the call data must be routed to the terrestrial network. This not only increases latency and affects user experience, but also makes calls impossible when problems occur on the terrestrial network.

[0153] In light of this, this application proposes a solution that uses a UE-satellite-UE (USU) method for calls between terminal devices. This allows media data (such as voice data) to be transmitted directly between terminal devices via satellite, without passing through the ground. This reduces satellite call latency and improves the user experience.

[0154] First, the network architecture proposed in the embodiment of the present application is introduced.

[0155] Refer to Figure 4, which is a schematic diagram of the network architecture proposed according to an embodiment of the present application. As shown in Figure 4, the IMS-AGW can be deployed on a satellite, so that when a call is made between terminal devices (such as UE-A and UE-B) accessed via a satellite, the call data can be transmitted using the USU method. Specifically, UE-A and UE-B can exchange call data through the IMS-AGW deployed on the satellite, and the call data can pass through the ground. There is no limitation on the deployment of the P-CSCF network element. A few examples are listed below.

[0156] In one example, the P-CSCF network element may be deployed on a satellite, as shown in (a) of FIG4 .

[0157] In another example, the P-CSCF network element may be deployed on the ground, as shown in (b) of FIG4 .

[0158] In another example, some functions of the P-CSCF network element are deployed on the satellite, and some functions are deployed on the ground.

[0159] For example, as shown in (c) in Figure 4, the P-CSCF network element is deployed on a satellite, and the application level gateway (ALG) in the P-CSCF network element is divided into two parts: satellite and ground. For example, the ALG deployed on the satellite is called ALG-sat, and the ALG deployed on the ground is called ALG-ground.

[0160] For another example, as shown in (d) in Figure 4, the P-CSCF network element is deployed on the ground, and the ALG in the P-CSCF network element is divided into two parts: satellite and ground. For example, the ALG deployed on the satellite is called ALG-sat, and the ALG deployed on the ground is called ALG-ground.

[0161] Optionally, core network elements are also deployed on the satellite, or the satellite can be considered to have the functions of access network elements. For example, core network elements include at least one of the following: a UPF element, an SMF element, a PCF element, etc. As shown in Figure 4, the UPF element is deployed on the satellite.

[0162] Optionally, the access network element is also deployed on the satellite, or the satellite is considered to have the function of the access network element. As an example, the access network element can be RAN.

[0163] In addition, based on the deployment scenarios of satellites and terrestrial networks, satellite network architectures can be divided into three categories: transparent satellite architecture, satellite backhaul architecture, and regenerative satellite architecture. The architecture in which the UE connects to the terrestrial access network via satellite can be called a transparent satellite architecture. The architecture in which the UE connects to the terrestrial access network and then connects to the terrestrial network via satellite can be called a satellite backhaul architecture. Furthermore, the architecture in which the access network equipment is included on the satellite is called a regenerative satellite architecture. All three of the above architectures are applicable to the embodiments of the present application.

[0164] The specific solution of this application is introduced below. Before introducing the specific solution of this application, the following points are explained.

[0165] (1) In this application, “indication” may include direct indication, indirect indication, explicit indication, and implicit indication. When describing that a certain indication information is used to indicate A, it can be understood that the indication information carries A, directly indicates A, or indirectly indicates A.

[0166] In this application, the information indicated by the indication information is referred to as the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein there is an association between the other information and the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, the indication of specific information can also be achieved with the help of the arrangement order of each information agreed in advance (for example, stipulated by the protocol), thereby reducing the indication overhead to a certain extent. In addition, the information to be indicated can be sent together as a whole, or it can be divided into multiple sub-information and sent separately, and the sending period and / or sending time of these sub-information can be the same or different.

[0167] (2) In this application, "sending" and "receiving" indicate the direction of signal transmission. For example, "sending information to XX" can be understood as the destination of the information being XX, which can include direct sending through the air interface, and also include indirect sending through the air interface by other units or modules. "Receiving information from YY" can be understood as the source of the information being YY, which can include direct receiving from YY through the air interface, and also include indirect receiving from YY through the air interface from other units or modules. "Sending" can also be understood as the "output" of the chip interface, and "receiving" can also be understood as the "input" of the chip interface. In other words, sending and receiving can be carried out between devices, for example, between a network device and a terminal device, or can be carried out within a device, for example, sending or receiving between components, modules, chips, software modules or hardware modules within the device through a bus, a line or an interface.

[0168] (3) In the various embodiments of this application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0169] (4) In this application, the terms "first" and "second" are used for convenience of description only and are not intended to limit the scope of the embodiments of this application. They are not used to describe the order or precedence of features. It should be understood that the terms described in this manner may be interchangeable, where appropriate, to describe solutions other than the embodiments of this application.

[0170] The method provided by the embodiment of the present application is described in detail below with reference to the accompanying drawings. The embodiment provided by the present application can be applied to the architecture shown in Figures 1 to 4 above, without limitation.

[0171] The embodiments described below do not specifically limit the specific structure of the execution subject of the method provided by the embodiments of the present application. As long as it is possible to communicate according to the method provided by the embodiments of the present application by running a program that records the code of the method provided by the embodiments of the present application, it is sufficient. For example, the execution subject of the method provided by the embodiments of the present application can be a receiving device or a sending device, or a functional module in the receiving device or the sending device that can call and execute the program. Without loss of generality, the communication method provided by the embodiments of the present application is described in detail below using the interaction between network elements as an example.

[0172] Referring to Figure 5, Figure 5 is a schematic diagram of a communication method 500 provided in an embodiment of the present application. The method 500 shown in Figure 5 may include the following steps.

[0173] 501. A first network element in an IMS receives a first request message from a first terminal, where the first request message is used to request establishment of a session with a second terminal.

[0174] The first terminal is accessed via satellite. In the embodiments of this application, it is mentioned multiple times that a terminal is accessed via satellite, which means that the terminal accesses a network via satellite, or that the terminal accesses a serving network (such as a serving PLMN) via satellite, or that the terminal's access technology is satellite access. The network accessed by the terminal via satellite may be an NTN network.

[0175] As an example, the IMS can also be replaced by a second network. For example, in step 501, a first network element in the second network receives a first request message from a first terminal, or a first network element in the second network receives a first request message from a first terminal via the first network. The first network is used to establish a connection between the second network (such as the IMS) and the terminal, that is, to enable communication between the terminal and the second network. As an example, the first network is an IP-CAN. As an example, the first network is EPS or 5GS.

[0176] In the embodiments of this application, IMS is used as an example for description. It should be understood that IMS is merely an example and its name does not limit the scope of protection of this application. This application does not exclude the possibility of using other names to replace IMS in future protocols to achieve the same or similar functions.

[0177] As an example, the first network element is a session control network element (such as a session control network element in an IMS). For example, the first network element is a P-CSCF network element, or a functional module (such as an ALG) in the P-CSCF network element.

[0178] As an example, the session control network element may be deployed on the ground, or the session control network element may be deployed on a satellite, or some functions of the session control network element may be deployed on a satellite and / or on the ground.

[0179] As an example, the first request message may also be referred to as a session request message or a session initiation message. The first request message is used to request establishment of a session with the second terminal. Alternatively, the first request message may be understood as requesting establishment of a call between the first terminal and the second terminal. In other words, the first request message is used to request establishment of a call with the second terminal. As an example, the first request message is a SIP request (SIP INVITE) message.

[0180] Optionally, method 500 further includes step 502 .

[0181] 502. A first network element in the IMS determines a first gateway in the IMS for a first terminal. The first gateway is used to transmit media data between the first terminal and a second terminal. The first gateway is deployed on a satellite.

[0182] The first network element in the IMS determines the first gateway for the first terminal, which can also be understood as: the first network element in the IMS determines the transmission resources for the first terminal, or the first network element in the IMS obtains (or determines, or requests) the transmission resources of the first terminal. Taking the first network element in the IMS determining the transmission resources for the first terminal as an example, the manner in which the first network element in the IMS determines the transmission resources for the first terminal may include: the first network element in the IMS determines the first gateway, and the first gateway determines the transmission resources for the first terminal. The transmission resources are used to transmit media data of the first terminal, that is, media data between the first terminal and the second terminal.

[0183] The first gateway, which may also be referred to as a satellite gateway, refers to a gateway deployed on a satellite, ie, a gateway on a satellite. As an example, the first gateway is an access gateway, such as an AGW or an IMS-AGW.

[0184] The second terminal refers to the terminal called by the first terminal. The second terminal may be accessed via a satellite.

[0185] 503. The first network element in the IMS sends a second request message to the first gateway, where the second request message is used to request transmission resources.

[0186] The transmission resource is used to transmit media data (such as call data) between the first terminal and the second terminal.

[0187] As an example, the transmission resource includes at least one of the following: an address (such as a source address, a destination address), or a port number (such as a source port number, a destination port number), etc.

[0188] Based on the above technical solution, after receiving a request message from a first terminal accessing via a satellite, a first network element in the IMS (such as a session control network element in the IMS) can determine a gateway deployed on the satellite for the first terminal and the transmission resources allocated by the gateway for the first terminal's media data (or media data between the first terminal and the second terminal). In this way, the media data between the first terminal and the second terminal can be transmitted directly by the gateway deployed on the satellite, that is, the media data between the first terminal and the second terminal does not need to pass through the ground. This shortens the latency of satellite calls and improves the user experience.

[0189] For ease of understanding, the following describes relevant solutions of the embodiments of the present application by taking the first network element as a P-CSCF network element as an example.

[0190] The session control network element serving the first terminal and the second terminal may be the same session control network element or different session control network elements. For example, if the first terminal and the second terminal may be registered or connected to the same session control network element, the session control network element of the first terminal and the second terminal is the same session control network element; for another example, if the first terminal and the second terminal are registered to different session control network elements, the session control network elements of the first terminal and the second terminal are different session control network elements. If the session control network element of the first terminal and the second terminal is the same session control network element, the session control network element (i.e., the session control network element in step 501) may know whether the first terminal and the second terminal are accessed via satellite; if the session control network elements of the first terminal and the second terminal are different session control network elements, the session control network element of the first terminal (i.e., the session control network element in step 501) may not know whether the second terminal is accessed via satellite, or the session control of the first terminal may learn whether the second terminal is accessed via satellite from the session control network element of the second terminal.

[0191] In one example, a first terminal and a second terminal are served by the same satellite. For example, the first terminal and the second terminal have the same serving PLMN. The serving PLMN of a terminal can be understood as the network currently accessed by the terminal. If the serving PLMN of the two terminals is the same, it can be understood that the two terminals are currently accessing the same network.

[0192] In one possible scenario, neither the first terminal nor the second terminal is roaming. In this scenario, both the serving PLMNs of the first terminal and the second terminal are HPLMNs, and the two HPLMNs are the same PLMN.

[0193] Another possible scenario is that the first terminal or the second terminal roams. In this case, for the roaming terminal, its serving PLMN is the VPLMN of the roaming terminal; for the non-roaming terminal, its serving PLMN is the HPLMN of the non-roaming terminal, and the VPLMN of the roaming terminal is the same as the HPLMN of the non-roaming terminal.

[0194] In another possible scenario, both the first terminal and the second terminal are roaming. In this scenario, the VPLMNs of the first terminal and the second terminal are the same. In addition, in this scenario, the HPLMNs of the first terminal and the second terminal may be the same or different, and this is not limited.

[0195] In another example, a link (e.g., an inter-satellite link) exists between the first terminal and the second terminal. For example, the first terminal and the second terminal are served by different satellites, and the satellite serving the first terminal and the satellite serving the second terminal belong to the same constellation. In another example, the first terminal and the second terminal are served by different satellites, and a link (e.g., an inter-satellite link) exists between the satellite serving the first terminal and the satellite serving the second terminal.

[0196] As an example, the media data between the first terminal and the second terminal includes: call data between the first terminal and the second terminal.

[0197] The session control network element determines the first gateway for the first terminal, which can also be understood as: in response to the first request message of the first terminal, the session control network element determines the first gateway; or, in response to the first request message of the first terminal, the session control network element allocates the first gateway.

[0198] Optionally, media data between the first terminal and the second terminal does not pass through the ground. In one possible implementation, media data between the first terminal and the second terminal does not pass through a second gateway in the IMS, and the second gateway is deployed on the ground. The second gateway, also referred to as a ground gateway, refers to a gateway deployed on the ground, i.e., a ground gateway. As an example, the second gateway is an access gateway, such as an AGW (e.g., an IMS-AGW) and / or a TrGW.

[0199] Based on this, media data between terminals can be exchanged directly via satellite without passing through the ground, which greatly shortens the satellite call delay and will not affect calls between terminals when problems occur in the ground network.

[0200] The phrase “media data does not pass through the ground” in the following embodiments may also be replaced with “media data does not pass through a gateway deployed on the ground”.

[0201] Among them, the session control network element determines the first gateway, which can be determined directly, that is, after the session control network element receives the request message from the first terminal, it directly determines the gateway deployed on the satellite; or it can also be determined under certain conditions, that is, after the session control network element receives the request message from the first terminal, it determines the gateway deployed on the satellite when it determines that certain conditions are met. In addition, as an example, the session control network element determines the first gateway, which can also be replaced by the session control network element determining that the first terminal and the second terminal perform USU communication (or are capable of performing USU communication), or can be replaced by the session control network element sending a second request message to the first gateway. USU communication means that media data (such as call data) can be transmitted directly between terminal devices via satellite, that is, media data between terminal devices can not pass through the ground. Taking the session control network element determining the first gateway as an example, several possible implementation methods are listed below.

[0202] In a first possible implementation, the session control network element determines the first gateway when the first terminal accesses via satellite. Based on this implementation, the session control network element determines the first gateway for the first terminal after determining that the first terminal accesses via satellite. Specifically, the first terminal may not use a gateway deployed on the satellite when accessing via terrestrial access. Therefore, the session control network element determines the first gateway deployed on the satellite after determining that the first terminal accesses via satellite, thus avoiding resource waste.

[0203] In one example, the session control network element can determine whether the first terminal accesses the network via satellite. For example, the SIP INVITE message in step 501 includes private (P)-access-network-info. The session control network element determines whether the first terminal accesses the network via satellite based on the P-access-network-info. For example, if the access type in the P-access-network-info includes satellite, the session control network element determines that the first terminal accesses the network via satellite.

[0204] In another example, the session control network element may learn from other network elements whether the first terminal accesses via satellite. For example, the session control network element learns from the UDM whether the first terminal accesses via satellite.

[0205] In a second possible implementation method, the session control network element determines the first gateway based on the contract information of the first terminal, wherein the contract information of the first terminal indicates that the media data of the first terminal is allowed to be transmitted without passing through the ground, or the contract information of the first terminal indicates that the first terminal has USU authorization.

[0206] As an example, the subscription information of the first terminal indicates the USU authorization information of the first terminal. As an example, the USU authorization information of the first terminal includes at least one of the following: whether the first terminal has USU authorization, the first terminal is accessed via satellite and can use the USU when satellite accesses a specific PLMN, or information about the session control network element registered with the first terminal. Alternatively, the first terminal having USU authorization may mean that media data of the first terminal does not pass through the ground.

[0207] Whether the first terminal has USU authorization indicates whether the first terminal supports USU communication (or USU calls), that is, whether the first terminal's media data (such as call data) is allowed (or can be) transmitted directly via satellite, that is, whether the first terminal's media data is allowed to be transmitted without going through the ground. USU communication means communicating directly via satellite, that is, without going through the ground.

[0208] Based on this, when the first terminal has USU authorization, the session control network element determines a gateway deployed on the satellite for the first terminal to avoid waste of resources.

[0209] The session control network element may store the contract information of the first terminal locally, or may read the contract information of the first terminal from another network element, which is not limited to this. The implementation method of the session control network element obtaining the contract information of the first terminal will be described later in conjunction with Figures 6 and 7.

[0210] In a third possible implementation, when the media data of the first terminal is allowed not to pass through the ground, the session control network element determines the first gateway.

[0211] In a fourth possible implementation, when the second terminal accesses via a satellite, or when both the first terminal and the second terminal access via a satellite, the session control network element determines the first gateway.

[0212] If the session control network element for the first terminal and the second terminal is the same, the session control network element can determine whether the first terminal and the second terminal are accessed via satellite. Regarding the manner in which the session control network element determines whether the first terminal and the second terminal are accessed via satellite, reference can be made to the description in the first possible implementation manner and is not further described here.

[0213] If the session control network elements of the first terminal and the second terminal are different, as an example, the session control network element of the first terminal can learn from the session control network element of the second terminal whether the second terminal is accessed via satellite.

[0214] A fifth possible implementation is that the session control network element determines the first gateway based on the contract information of the second terminal, or the session control network element determines the first gateway based on the contract information of the first terminal and the contract information of the second terminal, wherein the contract information of the first terminal indicates that the media data of the first terminal is allowed to not pass through the ground, and the contract information of the second terminal indicates that the media data of the second terminal is allowed to not pass through the ground. For example, the first terminal and the second terminal are registered to the same session control network element, so that the session control network element can obtain the contract information of the first terminal and the second terminal at the same time. For another example, the first terminal and the second terminal are registered to different session control network elements. As an example, the session control network element of the first terminal can obtain the contract information of the second terminal from the session control network element of the second terminal. This implementation method can refer to the second possible implementation method and will not be repeated here.

[0215] In a sixth possible implementation manner, when the first terminal and the second terminal are served by the same satellite, the session control network element determines the first gateway.

[0216] In a seventh possible implementation manner, when there is a link (such as an inter-satellite link) between the first terminal and the second terminal, the session control network element determines the first gateway.

[0217] The above-mentioned several possible implementations are illustrative and non-limiting. Any variation of the above-mentioned several methods is applicable to the embodiments of the present application. In addition, the above-mentioned several possible implementations can be used independently or in combination. For example, the above-mentioned sixth possible implementation or the seventh possible implementation can be used in combination with at least one of the above-mentioned first possible implementation to the fifth possible implementation.

[0218] Optionally, when the first terminal executes the IMS registration process, the session control network element obtains the subscription information of the terminal (such as the first terminal or the second terminal). In one possible implementation, the session control network element receives a registration request message from the first terminal, where the registration request message is used to request registration with the IMS; the session control network element sends a registration request message to the second network element in the IMS; and the session control network element receives a registration response message from the second network element in the IMS, where the registration response message includes the subscription information of the first terminal. As an example, the second network element in the IMS is an S-CSCF network element, or a functional module (such as an ALG) in the S-CSCF network element.

[0219] Taking the session control network element as a P-CSCF network element as an example, the schematic flow of the P-CSCF obtaining the subscription information is given below in conjunction with FIG6 and FIG7.

[0220] 6 , which is a schematic diagram of a UE performing IMS registration applicable to an embodiment of the present application. As an example, method 600 may be used in a non-roaming scenario. The method 600 shown in FIG6 may include the following steps.

[0221] 601. The UE sends a SIP registration message to the P-CSCF network element.

[0222] For example, the UE sends a SIP registration message to the P-CSCF network element through the established IMS PDU session and quality of service (QoS) flow to perform SIP registration.

[0223] As an example, the UE may be a calling UE (ie, a first terminal) or a called UE (ie, a second terminal). That is, both the calling UE and the called UE may perform SIP registration using method 600 .

[0224] 602. The P-CSCF network element sends a SIP registration message to the S-CSCF network element.

[0225] That is, the P-CSCF network element may forward the UE's SIP registration message to the S-CSCF network element.

[0226] 603. The S-CSCF network element obtains the subscription information of the UE from the UDM network element or the home subscriber server (HSS).

[0227] 604. The S-CSCF network element determines, based on the UE's subscription information, that the UE has USU authorization.

[0228] The UE's subscription information indicates the UE's USU authorization information. For example, the UE's USU authorization information includes at least one of the following: whether the UE has USU authorization, whether the UE is accessed via satellite and can use the USU when accessing a specific PLMN via satellite, or information about the P-CSCF network element with which the UE is registered.

[0229] Among them, whether the UE has USU authorization indicates whether the UE supports USU communication (or USU call), that is, whether the UE's media data (such as call data) is allowed (or can) be transmitted directly through the satellite, that is, whether the UE's media data is allowed to be transmitted without going through the ground.

[0230] Whether the UE has USU authorization can be implemented by one or more bits. For example, assuming that one bit is used to indicate whether the UE has USU authorization, if the bit is set to "0", it means that the UE has USU authorization; if the bit is set to "1", it means that the UE does not have USU authorization. It should be understood that the above is only an example and is not limiting.

[0231] In the embodiment of the present application, as an example, it is assumed that the authorization information of the UE indicates that the UE has USU authorization.

[0232] 605 , the S-CSCF network element sends a response message of the SIP registration message and the USU authorization information of the UE to the P-CSCF network element.

[0233] For example, assuming that the UE is successfully registered, the S-CSCF network element sends a SIP registration success message (such as 200 ok) to the P-CSCF network element.

[0234] Further optionally, the S-CSCF network element sends the USU authorization information of the UE to the P-CSCF network element. For example, if the UE has USU authorization, the S-CSCF network element may send the USU authorization information of the UE to the P-CSCF network element, where the USU authorization information of the UE includes at least one of the following: the UE has USU authorization (that is, the UE can support USU communication), the UE accesses via satellite and can use the USU when accessing a specific PLMN via satellite, or information about the P-CSCF network element with which the UE is registered.

[0235] The UE's USU authorization information and the response message of the SIP registration message can be transmitted through the same signaling or through different signaling, which is not limited. As an example, the SIP registration response message includes the UE's USU authorization information.

[0236] It can be understood that in step 605, an example is given in which the S-CSCF network element sends the USU authorization information of the UE to the P-CSCF network element, and this is not limited to this. For example, in step 605, the S-CSCF network element sends the UE's contract information to the P-CSCF network element, and the UE's contract information indicates the UE's USU authorization information.

[0237] 606. The P-CSCF network element saves the USU authorization information of the UE.

[0238] 607. The P-CSCF network element sends a response message of the SIP registration message to the UE.

[0239] As can be seen from the above, the P-CSCF network element can obtain the USU authorization information of the UE when the UE performs the IMS registration process, so that the USU authorization information can be directly read according to needs later.

[0240] For the specific process of UE performing IMS registration, please refer to the relevant description in 3GPP TS23.228, which is not limited to this.

[0241] 7 , which is another schematic diagram of a UE performing IMS registration applicable to an embodiment of the present application. As an example, method 700 may be used in a roaming scenario. Method 700 shown in FIG7 may include the following steps.

[0242] 701. The UE sends a SIP registration message to the P-CSCF network element in the VPLMN.

[0243] 702. The P-CSCF network element in the VPLMN forwards the SIP registration message to the IBCF network element in the HPLMN.

[0244] 703. The IBCF network element in the HPLMN forwards the SIP registration message to the S-CSCF network element in the HPLMN.

[0245] 704. The S-CSCF network element in the HPLMN obtains the UE's subscription information from the UDM network element or HSS in the HPLMN.

[0246] 705. The S-CSCF network element in the HPLMN determines that the UE has USU authorization based on the UE's subscription information.

[0247] 706. The S-CSCF network element in the HPLMN sends a response message of the SIP registration message and the USU authorization information of the UE to the IBCF network element in the HPLMN.

[0248] 707. The IBCF network element in the HPLMN saves the USU authorization information of the UE.

[0249] 708. The IBCF network element in the HPLMN sends a response message of the SIP registration message and the USU authorization information of the UE to the P-CSCF network element in the VPLMN.

[0250] 709. The P-CSCF network element in the VPLMN saves the USU authorization information of the UE.

[0251] 710. The P-CSCF network element in the VPLMN sends a response message of the SIP registration message to the UE.

[0252] Method 700 is similar to method 600, except that, in method 700, the IBCF network element in the HPLMN may also store the UE's USU authorization information. Furthermore, since this is a roaming scenario, as an example, when network elements in the VPLMN interact with network elements in the HPLMN, the interaction may be performed through the IBCF network element in the HPLMN.

[0253] Optionally, the session control network element also determines a second gateway, wherein the second gateway is deployed on the ground. Specifically, after receiving the first request message from the first terminal, the session control network element can also determine a gateway deployed on the ground for the first terminal. If the first terminal and the second terminal cannot communicate by USU, they can directly use the access network element on the ground to communicate, thereby reducing latency. In one possible implementation, the first network element in the IMS sends a third request message to the second gateway in the IMS, where the third request message is used to request transmission resources, and the transmission resources are used to transmit media data between the first terminal and the second terminal, and the second gateway is deployed on the ground.

[0254] Further optionally, if it is determined that the media data between the first terminal and the second terminal is allowed to not pass through the ground, the session control network element releases (or deallocates) the second gateway. Alternatively, if it is possible (or satisfied) to transmit the media data between the first terminal and the second terminal via a satellite (e.g., via a first gateway deployed on a satellite, or via the first gateway deployed on a satellite and other network elements deployed on a satellite), the session control network element releases the second gateway. Releasing the second gateway can also be understood as releasing the transmission resources allocated by the second gateway for the media data between the first terminal and the second terminal.

[0255] Optionally, if the first terminal is a roaming terminal, the second gateway may be determined by the session control network element or the border control network element (such as the IBCF network element) in the visited network. Specifically, the session control network element is deployed in the visited network, and the session control network element sends a first request message to the border control network element in the visited network, requesting the border network element to determine the second gateway for the first terminal. Accordingly, if it is determined that the media data between the first terminal and the second terminal is allowed not to pass through the ground, the session control network element or the border control network element may delete the second gateway. Alternatively, if it is possible (or satisfied) to transmit the media data between the first terminal and the second terminal via a satellite (such as through a first gateway deployed on a satellite, or through a first gateway deployed on a satellite and other network elements deployed on a satellite), the session control network element or the border control network element may delete the second gateway.

[0256] Optionally, if the first terminal is a roaming terminal, the session control network element in the visited network may further send instruction information to the network element in the home network, instructing whether to perform visited network routing. It is understood that the session control network element in the visited network may further send instruction information to the network element in the home network, and the visited network may send the instruction information to the network element in the home network via other network elements.

[0257] The indication information indicates whether to perform visited routing, which may also be replaced by: the indication information indicates whether to perform visited network routing for media data between the first terminal and the second terminal.

[0258] Executing visited network routing means that the media data of the first terminal can be directly forwarded by a network element in the visited network (such as a first gateway in the visited network) without passing through the home network.

[0259] In one possible implementation, indicating whether visited network routing is performed can be implemented using one or more bits. For example, assuming that a single bit indicates whether visited network routing is performed, if this bit is set to "0," it indicates that visited network routing is performed; if this bit is set to "1," it indicates that visited network routing is not performed. It should be understood that the above description is merely illustrative and not limiting.

[0260] Another possible implementation method is to indicate whether to perform visited network routing by whether to send a specific field. For example, assuming that whether to perform visited network routing is indicated by whether to send Field #1, if the session control network element in the visited network sends Field #1 to the network element in the home network, it indicates that visited network routing is performed; if the session control network element in the visited network does not send Field #1 to the network element in the home network, it indicates that visited network routing is not performed. It should be understood that the above description is merely an example and is not limiting.

[0261] The relevant solutions on whether to execute visited network routing will be described in detail later in conjunction with method X300.

[0262] Optionally, if the first terminal is a roaming terminal, the session control network element in the visited network may further receive instruction information sent from a network element in the home network, indicating whether to perform a loopback.

[0263] Executing loopback means that the media data of the first terminal can be directly forwarded by a network element in the visited network (such as a first gateway in the visited network) without passing through the home network.

[0264] In one possible implementation, indicating whether to execute a loopback can be implemented using one or more bits. For example, assuming a single bit indicates whether to execute a loopback, if the bit is set to "0," the loopback is executed; if the bit is set to "1," the loopback is not executed. It should be understood that the above is merely an example and not limiting.

[0265] Another possible implementation method is to indicate whether to execute a loopback by whether to send a specific field. For example, if the sending of field #2 indicates whether to execute a loopback, if the network element in the home network element sends field #2 to the session control network element in the visited network, it indicates that a loopback is executed; if the network element in the home network element does not send field #2 to the session control network element in the visited network, it indicates that a loopback is not executed. It should be understood that the above description is merely an example and is not limiting.

[0266] Regarding whether to execute loopback, the relevant solutions will be described in detail later in conjunction with method X400.

[0267] The above description is based on the perspective of session calls in conjunction with method 500. The following description focuses on the configuration of USU communication and is based on method 800. Method 800 and method 500 can be used in combination or separately. Any content not described in detail in method 800 can refer to the description of method 500.

[0268] Referring to Figure 8, Figure 8 is a schematic diagram of a communication method 800 provided in an embodiment of the present application. The method 800 shown in Figure 8 may include the following steps.

[0269] The method 800 includes step 802. Optionally, the method 800 includes step 801.

[0270] 801. An IMS network element determines a first gateway, where the first gateway is used to transmit media data between a first terminal and a second terminal. The first gateway is deployed on a satellite, and the first terminal and the second terminal are accessed via the satellite.

[0271] The IMS network element may be a network element located within the IMS. For example, the IMS network element may include at least one of the following: a session control network element, a gateway (such as an IMS-AGW), or other network elements within the IMS. For example, the IMS network element may be a P-CSCF network element or an S-CSCF network element.

[0272] Step 801 is similar to step 502. For example, the IMS network element may determine the first gateway according to the first to seventh possible implementations mentioned in method 500. For another example, the IMS network element may further determine the second gateway for the first terminal, etc. For the sake of brevity, detailed description is omitted here.

[0273] Optionally, before step 801, method 800 further includes: the IMS network element receives a session call message from the first terminal. This step is similar to step 501 and will not be described in detail here.

[0274] Optionally, before step 801, method 800 further includes: the IMS network element determining whether USU communication is performed between the first terminal and the second terminal. In other words, the IMS network element determines whether USU communication can be performed between the first terminal and the second terminal, or the IMS network element determines whether USU communication is possible between the first terminal and the second terminal. Specific determination methods, as examples, may refer to the first to seventh possible implementation methods mentioned in method 500, and are not described in detail here.

[0275] 802. The IMS network element sends information #A to the core network element. The information #A indicates whether USU communication is performed between the first terminal and the second terminal.

[0276] For example, if the IMS network element determines that USU communication may be performed between the first terminal and the second terminal, the IMS network element sends information #A to the core network element, where the information #A indicates that USU communication is performed between the first terminal and the second terminal.

[0277] For another example, if the IMS network element determines that USU communication is not possible between the first terminal and the second terminal, the IMS network element sends information #A to the core network element, where information #A indicates that USU communication is not performed between the first terminal and the second terminal; or, the IMS network element does not send information #A to the core network element.

[0278] As an example, the core network element includes at least one of the following: SMF, PCF, UPF, or other core network elements.

[0279] As an example, the IMS network elements in steps 801 and 802 may be the same or different. For example, the IMS network elements in steps 801 and 802 may both be session control network elements (such as P-CSCF network elements); or the IMS network element in step 801 may be a P-CSCF network element, and the IMS network element in step 802 may be an S-CSCF network element.

[0280] Among them, information #A indicates whether USU communication is performed between the first terminal and the second terminal, which can be replaced by: information #A indicates whether the first terminal and the second terminal exchange media data on the satellite, or information #A indicates whether the media data between the first terminal and the second terminal is exchanged on the satellite, or information #A indicates whether the media data between the first terminal and the second terminal passes through the ground. In addition, information #A indicates whether USU communication is performed between the first terminal and the second terminal, which can be a direct indication or an indirect indication. For example, information #A includes information that can be used to assist the core network element in determining whether USU communication is performed between the first terminal and the second terminal. Therefore, information #A can realize the function of indicating whether USU communication is performed between the first terminal and the second terminal.

[0281] As an example, information #A can be implemented using one or more bits. For example, assuming that one bit indicates whether USU communication is performed between the first terminal and the second terminal, if this bit is set to "0," it indicates that USU communication is performed between the first terminal and the second terminal; if this bit is set to "1," it indicates that USU communication is not performed between the first terminal and the second terminal. It should be understood that the above is merely an example and is not limiting.

[0282] As an example, information #A may be used to assist a core network element in determining whether USU communication is performed between the first terminal and the second terminal.

[0283] Optionally, the information #A includes at least one of the following: USU authorization information of the terminal (such as the first terminal and / or the second terminal), an identifier of the terminal (such as the first terminal and / or the second terminal), an address of the terminal (such as the first terminal and / or the second terminal), an access method of the terminal (such as the first terminal and / or the second terminal), a satellite providing service for the terminal (such as the first terminal and / or the second terminal), or description information. For details about the USU authorization information of the terminal, refer to the description of method 500. The following briefly introduces other information.

[0284] 1) Terminal identification: can be used to indicate (or identify) a terminal in a communication system, for example, to uniquely indicate a terminal in a communication system.

[0285] As an example, the identifier of the terminal includes at least one of the following: a uniform resource locator (URL) of the terminal (such as a SIP URL); a uniform resource identifier (URI) of the terminal (such as a telephone (TEL) URI); an IP multimedia private identity (IMPI) of the terminal, or including some bits within the IMPI; an IP multimedia public identity (IMPU) of the terminal, or including some bits within the IMPU; an international mobile subscriber identity (IMSI) of the terminal, or including some bits within the IMSI; a subscription permanent identifier (SUPI) of the terminal, or including some bits within the SUPI; or a subscription concealed identifier (SUCI) of the terminal, or including some bits within the SUCI.

[0286] 2) Terminal access method: Indicates whether the terminal accesses the network via the ground or via satellite.

[0287] 3) Satellite providing services to the terminal: indicates relevant information of the satellite providing services to the terminal, such as at least one of the following: satellite identifier, satellite constellation, whether there is an intersatellite link between the satellite constellation and other constellations, etc.

[0288] 4) Description information: This is description information of media data (such as call data) between the first terminal and the second terminal. The description information may indicate the media data that needs to be exchanged on the satellite (ie, USU communication).

[0289] As an example, the description information includes a service data flow (SDF) template, wherein the SDF template may include an IP triplet (source / destination address, source port number, protocol type) or an IP quintuple (destination address, destination port number, source address, source port number, protocol type). Taking the media data as call data as an example, for example, for the call data of the first terminal, the description information of the call data may include {source address = calling address / destination address = called address, source port number = calling port number / destination port number = called port number, protocol type = UDP} or IP quintuple {destination address = called address, destination port number = called port number, source address = calling address, source port number = calling port number, protocol type = UDP}; for the call data of the second terminal, the description information of the call data may include {source address = called address / destination address = calling address, source port number = called port number / destination port number = calling port number, protocol type = UDP} or IP quintuple {destination address = calling address, destination port number = calling port number, source address = called address, source port number = called port number, protocol type = UDP}.

[0290] 5) Terminal address: This may include the terminal's address information in an IP triplet or an IP quintuple. The IMS network element may obtain the terminal's address information through messages (such as session call messages, registration messages, etc.) sent by the terminal to the IMS network element, for example, by obtaining it from a SIP message sent by the terminal to the IMS network element (for example, from the message body of a SIP registration message or a SIP invite message). In addition, the terminal's SIP message may be sent to the IMS network element in the form of a data packet (such as an IP data packet). The IMS network element may also obtain the terminal's address information through the source address information carried in the packet header of the data packet (the packet header of the IP data packet carrying the SIP message. Alternatively, because the SIP message is implemented in the form of a data packet, the packet header of the data packet may also be understood as the message header of the SIP message). There are two ways to obtain the address information of the terminal based on the IMS. The address information of the terminal, for example, indicates the address of the terminal in the private network, such as the IP address assigned to the terminal by the SMF or UPF during the process of establishing the IMS PDU session. The terminal can carry the private network address when sending a SIP message to the IMS network element; or, the address information of the terminal can also indicate the address of the terminal in the public network, for example, the UPF serving the terminal can assign an address in the public network to the terminal. For example, when the terminal sends a SIP message to the IMS network element, the IP address in the packet header of the data packet carrying the SIP message (the private network address of the terminal at this time) is converted by the UPF through network address translation (NAT) to obtain the address in the public network after conversion; or, the address information of the terminal can also indicate an address determined based on the private network address and public network address of the terminal, such as a combination of the private network address and the public network address of the terminal. Correspondingly, the address information of the terminal in the first information may include the IP address in the message body of the SIP message from the terminal received by the IMS network element, and / or include the source address in the header of the data packet carrying the SIP message of the terminal received by the IMS network element.

[0291] Further optionally, if the IMS network element determines that the first terminal and the second terminal are served by the same PCF network element, the IMS network element sends information #A to the core network network element; or if the first terminal and the second terminal are served by the same PCF network element and the same SMF network element, the IMS network element sends information # to the core network network element. Based on this, when the IMS network element determines that the same first terminal and the second terminal are served by the same PCF network element (or: the same PCF network element and the same SMF network element), it sends information #A to the core network network element, which can increase the possibility of the core network network element successfully configuring USU communication. Specifically, if the IMS PDU sessions of the first terminal and the second terminal are served by different PCF network elements or different SMF network elements, it is difficult for the core network network element to configure USU communication. Therefore, in this case, USU communication can be achieved through other methods (such as the OMR mechanism). The IMS network element can determine whether the first and second terminals are served by the same PCF network element (or the same PCF network element and the same SMF network element). Alternatively, the IMS network element can request another network element to check, such as requesting the PCF network element of the first terminal to inquire whether the PCF network element of the second terminal is the same as the PCF network element of the first terminal. Furthermore, whether the PCF network element or SMF network element is the same can be determined by the core network element, which will be described in detail later.

[0292] Further, optionally, if the IMS network element determines that USU communication may be performed between the first terminal and the second terminal (e.g., through the first to seventh possible implementations mentioned in the above method 500), the IMS network element sends information #A to the core network element. For example, if the IMS network element determines that an inter-satellite link exists between the first terminal and the second terminal, or the IMS network element determines that the first terminal and the second terminal are served by the same satellite, or the IMS network element determines that the first terminal and the second terminal have USU authorization, the IMS network element sends information #A to the core network element.

[0293] Optionally, method 800 further includes step 803 .

[0294] 803. The core network element determines whether USU communication is performed between the first terminal and the second terminal.

[0295] Several possible ways in which a core network element determines whether USU communication is performed between a first terminal and a second terminal are described below.

[0296] In a possible implementation manner, the core network element determines whether to perform USU communication between the first terminal and the second terminal according to whether the first terminal and the second terminal are served by the same PCF network element.

[0297] For example, if the first terminal and the second terminal are served by the same PCF network element, the core network element determines that USU communication is performed between the first terminal and the second terminal. If the first terminal and the second terminal are served by different PCF network elements, the core network element may determine that USU communication is not performed between the first terminal and the second terminal, or the core network element may determine whether USU communication is performed between the first terminal and the second terminal according to other implementation methods.

[0298] Another possible implementation method is that the core network network element determines whether USU communication is performed between the first terminal and the second terminal based on whether the first terminal and the second terminal are served by the same PCF network element and SMF network element.

[0299] For example, if the first terminal and the second terminal are served by the same PCF network element and the same SMF network element, the core network network element determines that USU communication is performed between the first terminal and the second terminal. If the first terminal and the second terminal are served by different PCF network elements and / or different SMF network elements, the core network network element may determine that USU communication is not performed between the first terminal and the second terminal, or the core network network element may determine whether USU communication is performed between the first terminal and the second terminal according to other implementation methods.

[0300] In another possible implementation, the core network element determines whether USU communication is performed between the first terminal and the second terminal based on whether the first terminal and the second terminal are served by the same UPF network element.

[0301] For example, if the first terminal and the second terminal are served by the same UPF network element, the core network element determines that USU communication is performed between the first terminal and the second terminal. If the first terminal and the second terminal are served by different UPF network elements, the core network element may determine that USU communication is not performed between the first terminal and the second terminal. Alternatively, the core network element may determine whether USU communication is performed between the first terminal and the second terminal according to other implementation methods. For example, if there is a constellation link between the first terminal and the second terminal, the core network element may determine that USU communication is performed between the first terminal and the second terminal.

[0302] In another possible implementation manner, the core network element determines whether USU communication is performed between the first terminal and the second terminal according to whether a constellation link exists between the first terminal and the second terminal.

[0303] For example, if there is a constellation link between the first terminal and the second terminal, the core network network element determines that USU communication is performed between the first terminal and the second terminal. If there is no constellation link between the first terminal and the second terminal, the core network network element may determine that USU communication is not performed between the first terminal and the second terminal, or the core network network element may determine whether USU communication is performed between the first terminal and the second terminal according to other implementation methods.

[0304] In another possible implementation, information #A indicates whether USU communication is performed between the first terminal and the second terminal, and the core network element can directly learn whether USU communication is performed between the first terminal and the second terminal based on information #A.

[0305] In another possible implementation, the core network element may determine whether the terminal performs USU communication based on the USU authorization information of the terminal (such as the first terminal and / or the second terminal). As an example, information #A includes the USU authorization information of the terminal (such as the first terminal and / or the second terminal).

[0306] For example, if information #A includes USU authorization information of the first terminal, and the first terminal's USU authorization information indicates that the first terminal has USU authorization, the core network element determines that the first terminal and the second terminal can perform USU communication. In this case, the core network element may assume that the second terminal has USU authorization, or the core network element may learn that the second terminal has USU authorization through other means.

[0307] For another example, if information #A includes USU authorization information of the second terminal, then if the USU authorization information of the second terminal indicates that the second terminal has USU authorization, the core network element determines that the first terminal and the second terminal can perform USU communication. In this case, the core network element may assume that the first terminal has USU authorization, or the core network element may learn that the first terminal has USU authorization through other means.

[0308] For another example, information #A includes USU authorization information of the first terminal and USU authorization information of the second terminal. At this time, if the USU authorization information of the first terminal indicates that the first terminal has USU authorization, and the USU authorization information of the second terminal indicates that the second terminal has USU authorization, the core network network element determines that the first terminal and the second terminal can perform USU communication.

[0309] In another possible implementation, the core network element may determine whether the terminal performs USU communication based on the access mode of the terminal. As an example, the information #A includes the access mode of the terminal.

[0310] For example, if information #A includes the access method of the first terminal, and the access method of the first terminal indicates that the first terminal accesses via satellite, the core network element determines that the first terminal and the second terminal can perform USU communication. In this case, the core network element may assume that the second terminal also accesses via satellite, or the core network element may learn through other means that the second terminal also accesses via satellite.

[0311] For another example, if information #A includes the access method of the second terminal, and the access method of the second terminal indicates that the second terminal accesses via satellite, the core network element determines that the first terminal and the second terminal can perform USU communication. In this case, the core network element may assume that the first terminal also accesses via satellite, or the core network element may learn through other means that the first terminal also accesses via satellite.

[0312] For another example, information #A includes the access method of the first terminal and the access method of the second terminal. At this time, if the access method of the first terminal indicates that the first terminal accesses via satellite, and the access method of the second terminal indicates that the second terminal accesses via satellite, the core network network element determines that the first terminal and the second terminal can perform USU communication.

[0313] In another possible implementation, the core network element may determine whether the terminal performs USU communication based on information about a satellite providing services to the terminal (e.g., the first terminal and / or the second terminal). As an example, information #A includes information about a satellite providing services to the terminal (e.g., the first terminal and / or the second terminal).

[0314] For example, information #A includes information about satellites providing services for the first terminal and the second terminal. In this case, if the first terminal and the second terminal are served by the same satellite, or by different satellites and there are constellation links between different satellites, the core network element determines that the first terminal and the second terminal can perform USU communication.

[0315] The above-mentioned several implementations are for illustration only and are not intended to be limiting. Any variation of the above-mentioned several implementations is applicable to the embodiments of the present application. In addition, the above-mentioned several possible implementations can be used independently or in combination.

[0316] Assuming that the core network element determines that USU communication is performed between the first terminal and the second terminal, optionally, the method 800 further includes step 804.

[0317] 804. The core network element configures on-board switching routing.

[0318] Specifically, the core network element configures the media data between the first terminal and the second terminal to be exchanged and routed on board the satellite, that is, USU communication is performed between the first terminal and the second terminal.

[0319] Among them, the on-board switching route can also be replaced by on-board local routing, which means that data is exchanged on the satellite without passing through the ground.

[0320] Specifically, if the core network element determines that USU communication is performed between the first terminal and the second terminal, the core network element can be configured to perform satellite exchange of media data between the first terminal and the second terminal. For example, an on-board (local) UPF can be configured for the IMS PDU session of the first terminal and the second terminal, as well as rules for filtering data and / or for forwarding data, so that the terminal data is forwarded from the on-board UPF to the on-board gateway, thereby realizing USU communication. Among them, the rules for filtering data include, for example, packet detection rules (PDR), and the rules for forwarding data include, for example, forwarding action rules (FAR). The specific configuration method can refer to various existing or future defined methods and is not limited to this.

[0321] Optionally, method 800 further includes step 805 .

[0322] 805. The core network element sends a response of information #A to the IMS network element.

[0323] Specifically, after the core network element determines whether USU communication is performed between the first terminal and the second terminal, it can also send a response of information #A to the session control network element to notify the session control network element whether USU communication is performed between the first terminal and the second terminal.

[0324] Further optionally, after the core network element determines whether USU communication is performed between the first terminal and the second terminal, the core network element and / or the IMS network element may also notify the first terminal side and the second terminal side.

[0325] For example, if the core network element determines that USU communication is to be performed between the first terminal and the second terminal, and the core network element configures USU communication successfully, the core network element can notify the IMS network element, and then the IMS network element can send the address information of the first gateway (i.e., the gateway deployed on the satellite) to the terminal (such as the first terminal and / or the second terminal), so that the terminal can set the destination address to the address of the gateway on the satellite when sending data, thereby realizing USU communication. Similarly, as an example, if the media data between the first terminal and the second terminal passes through the ground, the IMS network element can send the address information of the second gateway (i.e., the gateway deployed on the ground) to the terminal (such as the first terminal and / or the second terminal), so that the terminal can set the destination address to the address of the gateway on the ground when sending data.

[0326] For ease of understanding, the following takes the first network element in IMS as the P-CSCF network element, the first gateway as the IMS-AGW (that is, unless otherwise specified below, IMS-AGW represents a gateway deployed on a satellite), the second gateway (that is, a gateway deployed on the ground) as a terrestrial access gateway (such as TrGW or IMS-AGW), the first terminal as the calling UE, and the second terminal as the called UE as an example to introduce the specific process applicable to the embodiments of the present application in combination with different scenarios. It can be understood that the process described below is only an example, and the embodiments of the present application are not limited to this. For the content not described in detail below, please refer to the description in method 500 or method 800, which will not be repeated below.

[0327] 9 is a schematic flow chart of a communication method 900 applicable to an embodiment of the present application. As an example, the method 900 can be used in a non-roaming scenario. The method 900 shown in FIG9 may include the following steps.

[0328] 901. The calling UE sends a SIP INVITE message to the P-CSCF network element.

[0329] Specifically, the calling UE initiates a SIP session, and the SIP INVITE message may be routed to the P-CSCF network element by the IP connectivity access network (IP-CAN). As an example, the IP-CAN may include EPS / 5GS.

[0330] 902. The P-CSCF network element interacts with the IMS-AGW to obtain transmission resources.

[0331] Among them, IMS-AGW is deployed on satellite.

[0332] The transmission resources may be used to transmit media data (e.g., call data) of the calling UE. Specifically, the transmission resources may be used to transmit media data between the calling UE and the called UE. Acquiring transmission resources may also be replaced by acquiring IMS-AGW resources, i.e., transmission resources used by the IMS-AGW to transmit media data of the calling UE.

[0333] The interaction refers to the transmission of signaling between the P-CSCF network element and the IMS-AGW network element.

[0334] For example, after receiving the SIP INVITE message, the P-CSCF network element determines (or selects) the IMS-AGW deployed on the satellite, and interacts with the IMS-AGW to obtain the transmission resource.

[0335] In one possible implementation, the P-CSCF network element may directly determine the IMS-AGW deployed on the satellite and interact with the IMS-AGW to obtain transmission resources.

[0336] In another possible implementation, if the calling UE is accessed via satellite, the P-CSCF network element determines an IMS-AGW deployed on the satellite and interacts with the IMS-AGW to obtain transmission resources. In other words, if the calling UE is not accessed via satellite, the IMS-AGW deployed on the satellite may not be selected, and step 902 is not performed.

[0337] In another possible implementation, the P-CSCF network element determines the IMS-AGW deployed on the satellite based on the USU authorization information and interacts with the IMS-AGW to obtain transmission resources. Regarding how the P-CSCF network element obtains USU authorization information, reference can be made to the aforementioned method 600 and will not be detailed here. Several possible scenarios are described below.

[0338] In a first possible scenario, the USU authorization information includes the USU authorization information of the calling UE.

[0339] For example, after the P-CSCF network element receives a SIP INVITE message from the calling UE, the P-CSCF network element queries the USU authorization information of the calling UE, and based on the USU authorization information of the calling UE, learns that the calling UE is accessed via a satellite and has USU authorization. Therefore, the P-CSCF network element determines the IMS-AGW deployed on the satellite and interacts with the IMS-AGW to obtain transmission resources.

[0340] On the contrary, if the calling UE is not accessed via a satellite and / or the calling UE does not have USU authorization, step 902 may not be performed.

[0341] In a second possible scenario, the USU authorization information includes the USU authorization information of the called UE.

[0342] If the called UE and the calling UE are registered with the same P-CSCF network element, the P-CSCF network element may store the USU authorization information of the called UE.

[0343] For example, after the P-CSCF network element receives a SIP INVITE message from a calling UE, the P-CSCF network element queries the USU authorization information of the called UE called by the calling UE, and based on the USU authorization information of the called UE, learns that the called UE is accessed via a satellite and has USU authorization. Therefore, the P-CSCF network element determines the IMS-AGW deployed on the satellite and interacts with the IMS-AGW to obtain transmission resources.

[0344] On the contrary, if the called UE is not accessed via a satellite and / or the called UE does not have USU authorization, step 902 may not be performed.

[0345] In addition, in this case, it may be assumed that the calling UE is accessed via satellite and has USU authorization.

[0346] In a third possible scenario, the USU authorization information includes the USU authorization information of the calling UE and the USU authorization information of the called UE.

[0347] If the called UE and the calling UE are registered with the same P-CSCF network element, the P-CSCF network element may store the USU authorization information of the calling UE and the called UE.

[0348] For example, after the P-CSCF network element receives a SIP INVITE message from a calling UE, the P-CSCF network element queries the USU authorization information of the calling UE and the USU authorization information of the called UE called by the calling UE, and based on the USU authorization information of the calling UE and the called UE, learns that the calling UE and the called UE are accessed via satellite and have USU authorization. Therefore, the P-CSCF network element determines the IMS-AGW deployed on the satellite and interacts with the IMS-AGW to obtain transmission resources.

[0349] On the contrary, if the calling UE and / or the called UE is not accessed via a satellite, step 902 may not be performed. In addition, if the calling UE and / or the called UE does not have USU authorization, step 902 may not be performed.

[0350] In the above-mentioned scenarios, the P-CSCF network element determines whether the UE accesses via satellite based on the UE's USU authorization information, which is not a limitation. As described in method 500, the P-CSCF network element may also determine whether the UE accesses via satellite based on the P-access-network info field or header field in the SIP INVITE message, or may obtain whether the UE accesses via satellite from the UDM.

[0351] 903. The P-CSCF network element interacts with the ground access gateway to obtain transmission resources.

[0352] The terrestrial access gateway refers to an access gateway deployed on the ground. This means that if media data between the calling and called UEs passes through the ground, it is forwarded by the terrestrial access gateway. For example, media data is sent to an AGW deployed on the ground, then from the AGW to a TrGW deployed on the ground, and then onwards. Another example is that media data is sent to a TrGW deployed on the ground and then onwards.

[0353] The transmission resources can be used to transmit media data (such as call data) between the calling UE and the called UE. Acquiring the transmission resources can also be replaced by acquiring the ground access gateway resources, that is, the transmission resources used by the ground access gateway to transmit the media data of the calling UE. It can be understood that the transmission resources in step 902 and step 903 are different. Specifically, the transmission resources in step 902 are used by the IMS-AGW to transmit the media data of the calling UE, and the transmission resources in step 903 are used by the ground access gateway to transmit the media data of the calling UE.

[0354] For example, after receiving the SIP INVITE message, the P-CSCF network element determines a ground access gateway deployed on the ground, and interacts with the ground access gateway to obtain transmission resources for transmitting media data.

[0355] For example, the P-CSCF network element follows the OMR mechanism when forwarding a SIP INVITE message, allowing subsequent media data transmission to bypass the terrestrial access gateway. For example, OMR can be used to add or remove IP address and domain information during the Session Description Protocol (SDP) offer / answer signaling exchange. The OMR mechanism is defined in TS 23.228 Annex Q and is not detailed here.

[0356] It is understandable that step 903 may not be performed. For example, if the P-CSCF network element determines in step 902 that the calling UE and the called UE are accessed via satellite and have USU authorization, then the media data between the calling UE and the called UE may not pass through the ground, and therefore there is no need to determine a ground access gateway, that is, there is no need to allocate ground transmission resources, and step 903 may not be performed.

[0357] 904. The P-CSCF network element forwards the SIP INVITE message to the S-CSCF network element.

[0358] 905. The S-CSCF network element forwards the SIP INVITE message to the remote side (terminating side).

[0359] The remote end refers to a network element related to the called UE. As an example, the remote end includes the called UE and a network element of the network where the called UE is located (such as an S-CSCF network element, etc.), which is not limited to this.

[0360] 906. The remote end sends an SDP response message to the S-CSCF network element.

[0361] Specifically, in response to the SIP INVITE message, the remote end sends an SDP answer message.

[0362] 907 , the S-CSCF network element forwards the SDP response message to the P-CSCF network element.

[0363] 908. The P-CSCF network element determines, based on the SDP response message, that media data is allowed to not pass through the ground access gateway, and deletes the allocated ground access gateway.

[0364] Specifically, after the P-CSCF network element receives the SDP response message, it learns from the SDP response message that the media data (such as call data) between the calling UE and the called UE can not pass through the ground (that is, the ground access gateway), that is, based on the IP address in the SDP response message, the information of the IP domain determines that the data bypasses (bypasses) the ground access gateway. Therefore, the allocated ground access gateway is deleted, that is, the transmission resources obtained by interacting with the ground access gateway in step 903 are released.

[0365] 909. The P-CSCF network element sends an SDP response message to the calling UE.

[0366] 910. The calling UE and the called UE complete session establishment.

[0367] It is understandable that step 910 may also include other steps to complete the session establishment, for example, reference may be made to the relevant description in Section 5.6.2 of standard TS23.228, which will not be described in detail here.

[0368] After the calling UE and the called UE complete the session establishment, the media data between the calling UE and the called UE can be locally exchanged through the IMS-AGW deployed on the satellite, that is, the media data between the calling UE and the called UE does not need to pass through the ground.

[0369] Based on the above solution, the media plane of the IMS system, such as the IMS-AGW, is deployed on the satellite. This allows the calling and called UEs to exchange media data via the satellite-based IMS-AGW, bypassing the ground-based media data flow. This reduces satellite call latency and improves the user experience. Furthermore, on-board switching can be achieved through OMR (Open Mobile Message Service). This means that the default path is from the satellite access gateway to the terrestrial access gateway. However, if both the calling and called UEs access the network via satellite, the terrestrial access gateway can be bypassed using the OMR mechanism.

[0370] Referring to Figure 10, Figure 10 is a schematic flow chart of a communication method 1000 applicable to an embodiment of the present application. As an example, the method 1000 can be used in a non-roaming scenario. The method 1000 shown in Figure 10 may include the following steps.

[0371] 1001. The calling UE sends a SIP INVITE message to the P-CSCF network element.

[0372] 1002. The P-CSCF network element interacts with the IMS-AGW to obtain transmission resources.

[0373] 1003. The P-CSCF network element interacts with the ground access gateway to obtain transmission resources.

[0374] 1004. The P-CSCF network element forwards the SIP INVITE message to the S-CSCF network element.

[0375] 1005. The S-CSCF network element forwards the SIP INVITE message to the remote end.

[0376] 1006. The remote end sends an SDP response message to the S-CSCF network element.

[0377] 1007. The S-CSCF network element forwards the SDP response message to the P-CSCF network element.

[0378] 1008. The P-CSCF network element sends information #A to the core network element (ie, the IP-CAN in the figure).

[0379] Optionally, when the P-CSCF network element determines that the calling UE and the called UE are served by the same PCF network element, it sends information #A to the core network network element; or, when the P-CSCF network element determines that the calling UE and the called UE are served by the same PCF network element and the same SMF network element, it sends information #A to the core network network element.

[0380] Optionally, if the P-CSCF network element determines that USU communication may be performed between the first terminal and the second terminal (e.g., through the first to seventh possible implementations mentioned in the above method 500), the P-CSCF network element sends information #A to the core network element. For example, if the P-CSCF network element determines that an inter-satellite link exists between the first terminal and the second terminal, or the P-CSCF network element determines that the first terminal and the second terminal are served by the same satellite, or the P-CSCF network element determines that the first terminal and the second terminal have USU authorization, the P-CSCF network element sends information #A to the core network element.

[0381] The information #A indicates whether USU communication is performed between the calling UE and the called UE. For information about the information #A, please refer to the relevant description in method 800 and will not be repeated here.

[0382] It is understood that the example of the P-CSCF network element sending information #A to the core network element is used for illustration and is not limiting. For example, other IMS network elements (such as the S-CSCF network element) can also send information #A to the core network element.

[0383] It can also be understood that step 1008 can also be performed before step 1002.

[0384] 1009. The core network element determines that USU communication is performed between the calling UE and the called UE, and configures on-board switching routing.

[0385] Specifically, after the core network element determines that USU communication is performed between the calling UE and the called UE, it can configure on-board switching routes for the calling UE and the called UE to enable on-board switching of media data between the calling UE and the called UE.

[0386] In method 1000 , it is assumed that USU communication can be performed between the calling UE and the called UE, that is, the core network element determines that USU communication is performed between the calling UE and the called UE.

[0387] Regarding step 1009, please refer to the relevant description in method 800, such as step 803, which will not be repeated here.

[0388] 1010. The core network element sends a response message of information #A to the P-CSCF element.

[0389] 1011. The P-CSCF network element sends an SDP response message to the calling UE.

[0390] Optionally, the P-CSCF network element further sends the address information of the IMS-AGW to the calling UE. The address information of the IMS-AGW is included in the SDP response message.

[0391] After receiving the response to message #A, the P-CSCF network element learns that USU communication can be performed between the calling UE and the called UE. Therefore, the P-CSCF network element can send the address information of the IMS-AGW deployed on the satellite to the calling UE, so that the calling UE can set the destination address to the address of the access gateway on the satellite when sending data, thereby achieving USU communication. On the other hand, when the P-CSCF learns that USU communication is not performed between the calling UE and the called UE, it can send the address information of the IMS-AGW deployed on the ground to the calling UE, so that the calling UE can set the destination address to the address of the access gateway on the ground when sending data, thereby achieving data routing through the ground.

[0392] 1012. The calling UE and the called UE complete session establishment.

[0393] It is understandable that step 1012 may also include other steps to complete the session establishment, for example, reference may be made to the relevant description in Section 5.6.2 of standard TS23.228, which will not be repeated here.

[0394] After the calling UE and the called UE complete the session establishment, the media data between the calling UE and the called UE can be locally exchanged through the IMS-AGW deployed on the satellite, that is, the media data between the calling UE and the called UE does not need to pass through the ground.

[0395] Based on the above solution, the media plane in the IMS system, such as the IMS-AGW, is deployed on a satellite. This allows the calling UE and the called UE to exchange media data via the satellite-based IMS-AGW, eliminating the need for ground-based communication. This reduces satellite call latency and improves user experience. Furthermore, core network configuration enables the exchange of media data between the calling and called UEs on the satellite. Furthermore, on-satellite switching can be implemented through core network configuration. Specifically, media data sent by the UE is routed to the satellite-based access gateway based on the core network configuration and the destination IP address entered by the UE. Furthermore, as an example, implementing on-satellite switching through core network configuration is applicable to scenarios where there are two anchor points (anchors) for the corresponding IMS PDU session. To distinguish these two anchor points, they are referred to as UPF anchor1 and UPF anchor2. On the satellite are the I (Intermediate) UPF, ULCL (Uplink Classification), BranchPoint (Branch Point), and LPSA UPF (Local PDU Session Anchor).

[0396] It is understood that the above method 1000 is illustrated using the calling UE side as an example. It should be noted that the logic of the IMS network element and the core network in this method is also applicable to the called UE side, that is, the IMS network element on the called UE side interacts with the core network element to enable on-board switching through the core network element. For example, when the P-CSCF network element of the called UE receives the SDP answer response sent by the called UE, it can send information #A to the core network element, so that the core network element determines that USU communication is performed between the calling UE and the called UE, and configures the on-board switching route.

[0397] It should be noted that the core network element may determine that USU communication is performed between the calling UE and the called UE based on a request from the P-CSCF serving the calling UE and / or the P-CSCF of the called UE.

[0398] 11 is a schematic flow chart of a communication method 1100 applicable to an embodiment of the present application. The method 1100 may be used in roaming scenarios, such as when a calling UE roams from an HPLMN to a VPLMN. The method 1100 shown in FIG11 may include the following steps.

[0399] 1101. The calling UE sends a SIP INVITE message to the P-CSCF network element in the VPLMN.

[0400] 1102. The P-CSCF network element in the VPLMN interacts with the IMS-AGW in the VPLMN to obtain transmission resources.

[0401] For example, the P-CSCF network element in the VPLMN can allocate transmission resources on the IMS-AGW according to the operator's policy.

[0402] 1103 , the P-CSCF network element in the VPLMN forwards the SIP INVITE message to the IBCF network element in the VPLMN.

[0403] 1104. The IBCF network element in the VPLMN interacts with the ground access gateway in the VPLMN to obtain transmission resources.

[0404] It is understandable that step 1104 may not be performed. For example, it may be assumed that the calling UE and the called UE can communicate using USU, and therefore step 1104 may not be performed.

[0405] 1105. The IBCF network element in the VPLMN forwards the SIP INVITE message to the IBCF network element in the HPLMN.

[0406] When a UE roams to a satellite PLMN (i.e., a VPLMN), the HPLMN (e.g., the HPLMN's IBCF network element) may decide not to perform home routing (i.e., not allocate terrestrial access gateway resources in the HPLMN) based on operator policy. For example, if the UE accesses via satellite, the HPLMN may decide not to perform home routing. For another example, if the UE has USU authorization, the HPLMN may decide not to perform home routing. For another example, if the UE accesses via satellite and has USU authorization, the HPLMN may decide not to perform home routing. This solution will be described in detail later in conjunction with steps 1200 and 1300.

[0407] 1106. The IBCF network element in the HPLMN forwards the SIP INVITE message to the S-CSCF network element in the HPLMN.

[0408] 1107. The S-CSCF network element in the HPLMN forwards the SIP INVITE message to the remote end.

[0409] 1108. The remote end sends an SDP response message to the S-CSCF network element in the HPLMN.

[0410] 1109. The S-CSCF network element in the HPLMN forwards the SDP response message to the IBCF network element in the HPLMN.

[0411] 1110. The IBCF network element in the HPLMN forwards the SDP response message to the IBCF network element in the VPLMN.

[0412] In addition, the IBCF network element in the VPLMN determines based on the SDP response message that the media data between the calling UE and the called UE may not pass through the ground (i.e., the ground access gateway allocated in step 1104), so the ground access gateway allocated between the VPLMN and the HPLMN can be deleted through the OMR.

[0413] 1111. The IBCF network element in the VPLMN forwards the SDP response message to the P-CSCF network element in the VPLMN.

[0414] 1112. The P-CSCF network element in the VPLMN sends an SDP response message to the calling UE.

[0415] For example, the P-CSCF network element in the VPLMN modifies the SDP answer message and sends the modified SDP answer message to the calling UE.

[0416] 1113. The calling UE and the called UE complete session establishment.

[0417] After the calling UE and the called UE complete the session establishment, the media data between the calling UE and the called UE can be locally exchanged through the IMS-AGW deployed on the satellite, that is, the media data between the calling UE and the called UE does not need to pass through the ground.

[0418] Method 1100 is similar to method 900, except that, in method 1100, network elements in the VPLMN and network elements in the HPLMN may interact via IBCF network elements. Furthermore, in method 1100, the P-CSCF network element may obtain the UE's USU authorization information in the manner described in method 700. Furthermore, during roaming, the HPLMN may determine not to perform home routing based on at least one of the following: the UE has satellite access, the UE has USU authorization, and an indication of on-board switching is possible.

[0419] Based on this solution, the media plane of the IMS system, such as the IMS-AGW, is deployed on the satellite. This allows the calling and called UEs to exchange media data via the satellite-based IMS-AGW, bypassing the ground-based network. This reduces satellite call latency and improves user experience. Furthermore, when the calling UE is roaming, LBO roaming can be used for routing, enabling media data exchange over the satellite.

[0420] Referring to Figure 12 , Figure 12 is a schematic flow chart of a communication method 1200 applicable to an embodiment of the present application. This method 1200 can be used in roaming scenarios, such as when both the calling UE and the called UE roam from the HPLMN to the VPLMN. In method 1200, a network element in the HPLMN can determine to perform VPLMN routing based on USU authorization information and on-board exchange indication information. Method 1200 shown in Figure 12 may include the following steps.

[0421] 1201. The calling UE sends a SIP INVITE message to the P-CSCF network element in the calling VPLMN.

[0422] For the sake of distinction, the calling VPLMN is referred to as the calling VPLMN, and the HPLMN corresponding to the calling is referred to as the calling HPLMN. Similarly, the called VPLMN is referred to as the called VPLMN, and the HPLMN corresponding to the called is referred to as the called HPLMN.

[0423] 1202. The P-CSCF network element in the calling VPLMN determines to perform USU communication based on the USU authorization information, and determines the IMS-AGW deployed on the satellite.

[0424] Specifically, if the P-CSCF network element in the calling VPLMN determines that the calling UE and the called UE can perform USU communication based on the USU authorization information, the IMS-AGW deployed on the satellite can be determined to transmit media data (such as call data) between the calling UE and the called UE.

[0425] As described in step 502, the P-CSCF network element in the calling VPLMN may also directly determine the IMS-AGW deployed on the satellite, or determine the IMS-AGW deployed on the satellite when certain conditions are met (such as the first to seventh possible implementations in the above method 500), without limitation. As an example, method 1200 only shows a solution in which the P-CSCF network element in the calling VPLMN determines the IMS-AGW deployed on the satellite based on the USU authorization information.

[0426] 1203 , the P-CSCF network element in the calling VPLMN interacts with the IMS-AGW in the calling VPLMN to obtain transmission resources.

[0427] Specifically, the P-CSCF network element in the calling VPLMN interacts with the IMS-AGW deployed on the satellite determined in step 1202 to obtain transmission resources for transmitting media data of the calling UE and the called UE.

[0428] Steps 1202-1203 may refer to step 902 in method 900 and are not described in detail here.

[0429] 1204. The P-CSCF network element in the calling VPLMN interacts with the terrestrial access gateway in the calling VPLMN to obtain transmission resources.

[0430] It is understandable that step 1204 may not be performed. For example, it may be assumed that the calling UE and the called UE can communicate using USU, so step 1204 may not be performed. For details, please refer to step 903 in method 900, which will not be described in detail here.

[0431] 1205. The P-CSCF network element in the calling VPLMN sends a SIP INVITE message to the IBCF network element in the calling HPLMN.

[0432] Optionally, the P-CSCF network element in the calling VPLMN sends an on-satellite switching indication message to the IBCF network element in the calling HPLMN. The on-satellite switching indication message may be carried in a SIP INVITE message or sent via separate signaling, which is not limited.

[0433] The on-satellite exchange indication information (or simply the indication information) indicates that media data can be exchanged (or allowed, or requested) on the satellite, that is, the media data of the calling UE and the called UE does not pass through the ground. The calling party can notify the called party through the on-satellite exchange indication information that the calling method can perform USU communication; accordingly, after the called party learns that the calling party can perform USU communication, it can also perform USU communication. For example, the called party can determine whether to perform USU communication based on the methods mentioned in method 500 (such as the first possible implementation method to the seventh possible implementation method).

[0434] It can be understood that the name of the on-board exchange indication information is only an example, and the name does not limit the protection scope of the embodiments of the present application.

[0435] 1206. The IBCF network element in the calling HPLMN determines to execute VPLMN routing according to the USU authorization information and / or the on-board switching indication information.

[0436] Among them, the IBCF network element in the calling HPLMN can obtain the USU authorization information of the UE (such as the calling UE) during the IMS registration process of the UE. For details, please refer to the relevant description in method 700, which will not be repeated here.

[0437] Implementation of VPLMN routing means that the calling UE's media data can be forwarded directly by network elements in the VPLMN (such as the IMS-AGW in the VPLMN) without passing through the HPLMN. Specifically, the calling UE's media data can be sent directly from the calling VPLMN to the called party, without having to be sent from the calling VPLMN to the calling HPLMN and then from the calling HPLMN to the called party.

[0438] Specifically, after the IBCF network element in the calling HPLMN determines to implement VPLMN routing, media data between the calling UE and the called UE may not pass through the HPLMN. Therefore, terrestrial access gateway resources (terrestrial access gateway resources) in the HPLMN may not be allocated. Conversely, if the IBCF network element in the calling HPLMN determines not to implement VPLMN routing, that is, media data between the calling UE and the called UE must pass through the HPLMN, then the IBCF network element in the calling HPLMN must allocate terrestrial access gateway resources in the HPLMN.

[0439] In one possible implementation, the IBCF network element in the calling HPLMN determines to execute VPLMN routing based on USU authorization information. For example, the USU authorization information includes USU authorization information of the calling UE. If the USU authorization information of the calling UE indicates that the calling UE has USU authorization, the IBCF network element in the calling HPLMN determines to execute VPLMN routing. Conversely, if the USU authorization information of the calling UE indicates that the calling UE does not have USU authorization, the IBCF network element in the calling HPLMN determines not to execute VPLMN routing.

[0440] In another possible implementation, the IBCF network element in the calling HPLMN determines to execute VPLMN routing based on the on-satellite switching indication information. For example, if the IBCF network element in the calling HPLMN receives an on-satellite switching indication from the P-CSCF network element in the calling VPLMN, the IBCF network element in the calling HPLMN determines to execute VPLMN routing. Conversely, if the IBCF network element in the calling HPLMN does not receive an on-satellite switching indication from the P-CSCF network element in the calling VPLMN (or if the IBCF network element in the calling HPLMN receives an on-satellite switching non-indication from the P-CSCF network element in the calling VPLMN), the IBCF network element in the calling HPLMN determines not to execute VPLMN routing.

[0441] In another possible implementation, the IBCF network element in the calling HPLMN determines to execute VPLMN routing based on the USU authorization information and the on-satellite switching indication information. For example, if the IBCF network element in the calling HPLMN receives an on-satellite switching indication from the P-CSCF network element in the calling VPLMN, and the USU authorization information of the calling UE indicates that the calling UE has USU authorization, the IBCF network element in the calling HPLMN determines to execute VPLMN routing; otherwise, the IBCF network element in the calling HPLMN determines not to execute VPLMN routing.

[0442] The above-mentioned implementations are provided as examples and are not intended to be limiting. For example, the IBCF network element in the calling HPLMN may directly determine to execute VPLMN routing, or determine to execute VPLMN routing when certain conditions are met, without limitation. The conditions to be met may refer to the conditions referenced by the session control network element when determining the first access gateway in method 500 (i.e., the first to seventh possible implementations), and are not further described here.

[0443] Furthermore, the calling IMS may indicate to the called IMS whether "on-satellite exchange is possible", that is, whether the media data between the calling UE and the called UE can be exchanged on the satellite without passing through the ground. Optionally, when the calling VPLMN instructs the calling HPLMN to send the called IMS whether "on-satellite exchange is possible", for example, when the called UE is also a roaming UE (e.g., the calling VPLMN is not the called HPLMN), the instruction may be sent. When the called UE is a non-roaming UE (e.g., the calling VPLMN is the called HPLMN), no instruction may be given or an instruction may be given not to send.

[0444] As an example, the calling IMS may indicate to the called IMS whether "on-board exchange is possible", for details, refer to steps 1207-1209.

[0445] 1207. The IBCF network element in the calling HPLMN sends a SIP INVITE message to the S-CSCF network element in the calling HPLMN.

[0446] Optionally, the IBCF network element in the calling HPLMN further sends on-board switching indication information to the S-CSCF network element in the calling HPLMN.

[0447] 1208. The S-CSCF network element in the calling HPLMN sends a SIP INVITE message to the S-CSCF network element in the called HPLMN.

[0448] Optionally, the S-CSCF network element in the calling HPLMN further sends on-satellite switching indication information to the S-CSCF network element in the called HPLMN.

[0449] 1209. The S-CSCF network element in the called HPLMN sends a SIP INVITE message to the IBCF network element in the called HPLMN.

[0450] Optionally, the S-CSCF network element in the called HPLMN further sends on-board switching indication information to the IBCF network element in the called HPLMN.

[0451] 1210. The IBCF network element in the called HPLMN determines to execute VPLMN routing according to the USU authorization information and / or the on-board switching indication information.

[0452] As an example, the USU authorization information includes USU authorization information of the called UE.

[0453] It is understandable that if the called party also has a roaming UE, VPLMN routing can also be performed (ie, no terrestrial access gateway resources are allocated in the HPLMN).

[0454] The step 1210 may refer to the step 1206 and will not be described in detail here.

[0455] 1211. The IBCF network element in the called HPLMN sends a SIP INVITE message to the P-CSCF network element in the called VPLMN.

[0456] 1212. The P-CSCF network element in the called VPLMN determines to execute VPLMN routing and on-board switching.

[0457] 1213. The P-CSCF network element in the called VPLMN interacts with the IMS-AGW in the called VPLMN to obtain transmission resources.

[0458] 1214. The IMS-AGW in the called VPLMN sends a SIP INVITE message to the called UE.

[0459] Alternatively, in step 1214, the P-CSCF network element in the called VPLMN may send a SIP INVITE message to the called UE.

[0460] 1215. The called UE sends an SDP response message to the P-CSCF network element in the called VPLMN.

[0461] 1216. The P-CSCF network element in the called VPLMN sends an SDP response message to the IBCF network element in the called HPLMN.

[0462] 1217. The IBCF network element in the called HPLMN sends an SDP response message to the S-CSCF network element in the called HPLMN.

[0463] 1218. The S-CSCF network element in the called HPLMN sends an SDP response message to the S-CSCF network element in the calling HPLMN.

[0464] 1219. The S-CSCF network element in the calling HPLMN sends an SDP response message to the IBCF network element in the calling HPLMN.

[0465] 1220. The IBCF network element in the calling HPLMN sends an SDP response message to the P-CSCF network element in the calling VPLMN.

[0466] 1221. The P-CSCF network element in the calling VPLMN determines to perform on-board switching.

[0467] Specifically, the P-CSCF network element in the calling VPLMN can determine to perform on-satellite switching based on the SDP response message. This means that media data between the calling UE and the called UE is exchanged on the satellite without passing through the ground. Therefore, the P-CSCF network element in the calling VPLMN can further optionally delete the terrestrial access gateway in the calling VPLMN through the OMR. If a terrestrial access gateway is also assigned to the HPLMN, this terrestrial access gateway can also be deleted.

[0468] 1222. The P-CSCF network element in the calling VPLMN sends an SDP response message to the calling UE.

[0469] 1223. The calling UE and the called UE complete session establishment.

[0470] Based on the above solution, the media plane in the IMS system, such as the IMS-AGW, is deployed on the satellite. In this way, the calling UE and the called UE can exchange media data through the IMS-AGW deployed on the satellite, and the media data does not need to pass through the ground, which shortens the satellite call latency and improves the user experience. In addition, when the calling UE is a roaming UE, the calling HPLMN (such as the IBCF network element in the calling HPLMN) can determine whether to execute VPLMN routing based on USU authorization information (such as the USU authorization information of the calling UE) and the on-satellite exchange indication information. In addition, if the called UE is also a roaming UE, the called HPLMN (such as the IBCF network element in the called HPLMN) can also determine whether to execute VPLMN routing based on USU authorization information (such as the USU authorization information of the called UE) and the on-satellite exchange indication information. In addition, when VPLMN routing is executed, terrestrial access gateway resources may not be allocated in the HPLMN.

[0471] Referring to Figure 13 , Figure 13 is a schematic flow chart of a communication method 1300 applicable to an embodiment of the present application. This method 1300 can be used in roaming scenarios, such as when a calling UE roams from an HPLMN to a VPLMN. In method 1300 , a network element in the HPLMN can determine to execute loopback based on USU authorization information. Method 1300 shown in Figure 13 may include the following steps.

[0472] 1301. The calling UE sends a SIP INVITE message to the P-CSCF network element in the calling VPLMN.

[0473] 1302. The P-CSCF network element in the calling VPLMN determines to perform USU communication based on the USU authorization information, and determines the IMS-AGW deployed on the satellite.

[0474] Similar to step 1202, the P-CSCF network element in the calling VPLMN can also directly determine the IMS-AGW deployed on the satellite, or determine the IMS-AGW deployed on the satellite when certain conditions are met (such as the first to seventh possible implementation methods in the above method 500), which is not limited to this.

[0475] 1303 , the P-CSCF network element in the calling VPLMN interacts with the IMS-AGW in the calling VPLMN to obtain transmission resources.

[0476] Optionally, the P-CSCF network element in the calling VPLMN interacts with the terrestrial access gateway in the calling VPLMN to obtain transmission resources.

[0477] 1304. The P-CSCF network element in the calling VPLMN sends a SIP INVITE message to the IBCF network element in the calling HPLMN.

[0478] Optionally, the P-CSCF network element in the calling VPLMN may further send on-board exchange indication information to the IBCF network element in the calling HPLMN.

[0479] 1305. The IBCF network element in the calling HPLMN sends a SIP INVITE message to the S-CSCF network element in the calling HPLMN.

[0480] Optionally, the IBCF network element in the calling HPLMN further sends on-board switching indication information to the S-CSCF network element in the calling HPLMN.

[0481] 1306. The S-CSCF network element in the calling HPLMN determines to execute loopback according to the USU authorization information and / or the on-board exchange indication information.

[0482] Loopback, also known as VPLMN routing, means that the calling UE's call flow and media data can be directly routed and forwarded by network elements in the VPLMN (such as the IMS-AGW in the VPLMN) without passing through the HPLMN. Specifically, the calling UE's call flow and media data can be sent directly from the calling VPLMN to the called party, without having to be sent from the calling VPLMN to the calling HPLMN and then from the calling HPLMN to the called party.

[0483] In one possible implementation, the S-CSCF network element in the calling HPLMN determines to execute loopback based on USU authorization information. For example, the USU authorization information includes the USU authorization information of the calling UE. If the USU authorization information of the calling UE indicates that the calling UE has USU authorization, the S-CSCF network element in the calling HPLMN determines to execute loopback. Conversely, if the USU authorization information of the calling UE indicates that the calling UE does not have USU authorization, the S-CSCF network element in the calling HPLMN determines not to execute loopback. In this case, in step 1304, the P-CSCF network element in the calling VPLMN may also not send the on-board switching indication information.

[0484] In another possible implementation, the S-CSCF network element in the calling HPLMN determines to execute loopback based on the on-satellite switching indication information. For example, if the S-CSCF network element in the calling HPLMN receives an on-satellite switching indication from the P-CSCF network element in the calling VPLMN, the S-CSCF network element in the calling HPLMN determines to execute loopback. Conversely, if the S-CSCF network element in the calling HPLMN does not receive an on-satellite switching indication from the P-CSCF network element in the calling VPLMN (or the S-CSCF network element in the calling HPLMN receives an on-satellite switching indication from the P-CSCF network element in the calling VPLMN), the S-CSCF network element in the calling HPLMN determines not to execute loopback.

[0485] In another possible implementation, the S-CSCF network element in the calling HPLMN determines to execute loopback based on the USU authorization information and the on-satellite switching indication information. For example, if the S-CSCF network element in the calling HPLMN receives an on-satellite switching indication from the P-CSCF network element in the calling VPLMN, and the USU authorization information of the calling UE indicates that the calling UE has USU authorization, the S-CSCF network element in the calling HPLMN determines to execute loopback; otherwise, the S-CSCF network element in the calling HPLMN determines not to execute loopback.

[0486] The above-mentioned implementations are provided as examples and are not intended to be limiting. For example, the S-CSCF network element in the calling HPLMN may directly determine to execute a lookback, or determine to execute a lookback when certain conditions are met, without limitation. The conditions to be met may refer to the conditions used by the session control network element in determining the first access gateway in method 500 (i.e., the first to seventh possible implementations), and are not described in detail here.

[0487] Further optionally, the calling HPLMN may notify the calling VPLMN to execute loopback, as shown in steps 1307-1308.

[0488] 1307. The S-CSCF network element in the calling HPLMN sends loopback indication information to the IBCF network element in the calling HPLMN.

[0489] The loopback indication information indicates that loopback is allowed to be executed.

[0490] Optionally, the S-CSCF network element in the calling HPLMN may further send a SIP INVITE message of the calling UE to the IBCF network element in the calling HPLMN.

[0491] 1308. The IBCF network element in the calling HPLMN sends loopback indication information to the P-CSCF network element in the calling VPLMN.

[0492] Optionally, the IBCF network element in the calling HPLMN may further send a SIP INVITE message of the calling UE to the P-CSCF network element in the calling VPLMN.

[0493] 1309. The P-CSCF network element in the calling VPLMN sends a SIP INVITE message and an on-board switching indication to the remote end.

[0494] 1310. The remote end determines to execute a lookback based on the USU authorization information and / or the on-board exchange indication.

[0495] The USU authorization information may include the USU authorization information of the calling UE and / or the USU authorization information of the called UE.

[0496] For specific operations at the remote end, please refer to the relevant operations involving the called party (such as the called UE, the called VPLMN, and the network element in the called HPLMN) in 1200, which will not be described in detail here.

[0497] 1311. The remote end sends an SDP response message to the S-CSCF network element in the calling HPLMN.

[0498] 1312. The S-CSCF network element in the calling HPLMN sends an SDP response message to the P-CSCF network element in the calling VPLMN.

[0499] Specifically, the S-CSCF network element in the calling HPLMN may send an SDP response message to the P-CSCF network element in the calling VPLMN via an IBCF network element (such as an IBCF network element in the calling HPLMN and / or the calling VPLMN).

[0500] 1313. The P-CSCF network element in the calling VPLMN determines to perform on-board switching.

[0501] In other words, the P-CSCF network element in the calling VPLMN configures on-board switching.

[0502] 1314. The P-CSCF network element in the calling VPLMN sends an SDP response message to the calling UE.

[0503] 1315. The calling UE and the called UE complete session establishment.

[0504] Method 1300 is similar to method 1200, except that, in method 1300, when a UE (such as a calling UE) accesses a network via a satellite, the HPLMN (such as an S-CSCF network element in the HPLMN) determines to execute a loopback and sends a loopback indication to the VPLMN (such as a P-CSCF network element in the VPLMN).

[0505] The above text introduces several possible call flows by way of example in conjunction with Figures 9 to 13. The above steps are merely exemplary and are not strictly limited to this. For example, in the above 9 to 13, the P-CSCF network element mainly determines the IMS-AGW deployed on the satellite based on the USU authorization information, but this is not limited to this. For example, the P-CSCF network element can also directly determine the IMS-AGW deployed on the satellite. For details, please refer to the description of step 502. In addition, the size of the sequence number of each of the above processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application. In addition, the above schemes can be reasonably combined. For example, the operations involving the remote end in methods 900, 1100, and 1300 can refer to the description in method 1200.

[0506] The OMR mechanism was mentioned above. The following is a brief introduction to the OMR mechanism.

[0507] See Figure 14, which is a schematic diagram of an OMR mechanism applicable to an embodiment of the present application. Method 1400 is primarily described using the IMS-ALG functional module in the P-CSCF network element as an example. Assuming IMS-ALGs are deployed both on satellite and on the ground, for differentiation, the IMS-ALG deployed on the satellite on the calling side is referred to as IMS-ALG11, and the IMS-ALG deployed on the ground is referred to as IMS-ALG12; the IMS-ALG deployed on the satellite on the called side is referred to as IMS-ALG21, and the IMS-ALG deployed on the ground is referred to as IMS-ALG22. Method 1400 can be used in methods 900-1300 described above. Method 1400 shown in Figure 14 may include the following steps.

[0508] 1401. After receiving the SDPoffer from the calling UE, the IMS-ALG11 allocates the IMS-AGW1 deployed on the satellite.

[0509] For the purpose of distinction, the IMS-AGW deployed on the satellite on the calling side is referred to as IMS-AGW1, and the IMS-AGW deployed on the satellite on the called side is referred to as IMS-AGW2.

[0510] Specifically, the calling UE sends a SIP INVITE message to IMS-ALG 11, which includes an SDPoffer. After receiving the SDPoffer, IMS-ALG 11 allocates IMS-AGW 1, deployed on the satellite, to transmit media data between the calling and called UEs over the satellite. As shown in Figure 14, assume that IMS-ALG 11 and IMS-ALG 12 are in realm R1. That is, IMS-AGW 1 is in realm R1 and has an address of IP1. Rx represents the previously associated IP realm.

[0511] 1402. IMS-ALG11 forwards the SDPoffer to IMS-ALG12.

[0512] 1403, IMS-ALG12 allocates a ground access gateway.

[0513] Specifically, after receiving the SDPoffer, the IMS-ALG 12 may allocate an access gateway deployed on the ground to transmit media data between the calling UE and the called UE on the ground.

[0514] Assume that IMS-ALG12 and IMS-ALG21 are in realm R2. That is, the domain where the ground access gateway is located is R2, and the address is IP2.

[0515] 1404. IMS-ALG12 forwards the SDPoffer to IMS-ALG22.

[0516] 1405 , the outgoing realm of IMS-ALG 22 is R1, so IMS-ALG 22 bypasses the access network element on the ground.

[0517] Specifically, if the domain of the called party is the same as that of the calling party, that is, both are R1, the IMS-ALG 22 does not allocate a terrestrial access gateway. Alternatively, when the called UE is a roaming UE, no terrestrial access gateway is allocated.

[0518] 1406. IMS-ALG22 forwards the SDPoffer to IMS-ALG21.

[0519] As shown in FIG14 , since the domain of the called party and the domain of the calling party are both R1, when IMS-ALG22 forwards the SDPoffer to IMS-ALG21, R2 and IP2 are deleted (or bypassed) from the carried address information.

[0520] 1407, IMS-ALG21 allocates IMS-AGW2 deployed on the satellite.

[0521] Specifically, after receiving the SDPoffer from the calling UE, IMS-ALG21 allocates IMS-AGW2 deployed on the satellite to transmit media data between the calling UE and the called UE on the satellite. As shown in Figure 14, assume that the domain where IMS-AGW2 is located is R1 and its address is IP3.

[0522] 1408 , IMS-ALG21 sends an SDP response message to IMS-ALG22 .

[0523] In response to the SDPoffer, the IMS-ALG 21 sends an SDP answer message.

[0524] As shown in FIG14 , since the domains of the called party and the calling party are both R1, IMS-ALG21 sends an SDP response message to IMS-ALG22, which carries address information including IMS-AGW2's address IP3 and domain R1.

[0525] 1409 , IMS-ALG22 sends an SDP response message to IMS-ALG12 .

[0526] 1410, IMS-ALG12 releases the ground access gateway.

[0527] For example, after IMS-ALG12 receives the SDP response message, R2 and IP2 are deleted from the SDP response message. Therefore, IMS-ALG12 determines that it is possible (or meets the requirements) to transmit media data between the calling UE and the called UE via satellite (such as through the IMS-AGW deployed on the satellite, or through the IMS-AGW deployed on the satellite and other network elements deployed on the satellite), thereby releasing the terrestrial access gateway, that is, releasing the transmission resources allocated by the terrestrial access gateway for the media data between the calling UE and the called UE.

[0528] 1411. IMS-ALG12 forwards the SDP response message to IMS-ALG11.

[0529] 1412 , the calling UE and the called UE perform on-board switching through IMS-ALG11 and IMS-ALG12.

[0530] Specifically, media data between the calling UE and the called UE is exchanged through IMS-AGW1 and IMS-AGW2.

[0531] The OMR mechanism is briefly introduced above in conjunction with Figure 14, but the embodiments of the present application are not limited thereto. For a detailed introduction to the OMR mechanism, please refer to the relevant description in TS23.228, which will not be repeated here.

[0532] It will be appreciated that in some of the above embodiments, the calling UE side is primarily used as an example, and this is not limiting. For example, the P-CSCF network element on the called UE side may also determine whether USU communication is being performed between the calling UE and the called UE. In another example, the IMS network element on the called UE side (such as the P-CSCF network element) interacts with the core network element to enable on-board switching through the core network element.

[0533] It can also be understood that in some of the above embodiments, "forwarding" is mentioned. For example, the P-CSCF network element forwards the SIP registration message. It can be understood that forwarding here means that the P-CSCF network element forwards the received SIP registration message to other network elements. Specifically, when forwarding, the P-CSCF network element can also process the SIP registration message according to transmission requirements (for example, add, delete, or modify part or all of the information in the message header).

[0534] It is also understood that in some of the above embodiments, network elements or gateways are repeatedly mentioned as being deployed on a satellite or on the ground. Taking the example of a gateway being deployed on a satellite, this can mean that the gateway is set up on the satellite, or that the satellite has the gateway function, and this is not limited to this.

[0535] It can also be understood that some optional features in the various embodiments of the present application may not depend on other features in certain scenarios, and may also be combined with other features in certain scenarios, without limitation.

[0536] It can also be understood that the solutions in the various embodiments of the present application can be reasonably combined and used, and the explanations or descriptions of the various terms appearing in the embodiments can be referenced or explained with each other in the various embodiments, without limitation to this.

[0537] It can also be understood that in the above-mentioned various method embodiments, the methods and operations implemented by devices (such as terminal devices, network devices) can also be implemented by components of the devices (such as chips or circuits) without limitation.

[0538] The method provided in the embodiments of the present application is described in detail above with reference to Figures 5 to 14. Below, the apparatus provided in the embodiments of the present application is described in detail with reference to Figures 15 to 17. It should be understood that the description of the apparatus embodiment corresponds to the description of the method embodiment. Therefore, for matters not described in detail, reference can be made to the method embodiment above, and for the sake of brevity, they will not be repeated here.

[0539] Referring to Figure 15 , Figure 15 is a schematic diagram of a communication device 1500 provided in an embodiment of the present application. Device 1500 includes a transceiver unit 1510. Transceiver unit 1510 can be used to implement corresponding communication functions. Transceiver unit 1510 can also be referred to as a communication interface or a communication unit. Optionally, device 1500 also includes a processing unit 1520. Processing unit 1520 can be used to perform processing, such as determining an access gateway or allocating transmission resources.

[0540] Optionally, the device 1500 may further include a storage unit, which may be used to store instructions and / or data. The processing unit 1520 may read the instructions and / or data in the storage unit so that the device implements the aforementioned method embodiment.

[0541] Optionally, the transceiver unit 1510 may include a receiving unit and a sending unit, wherein the receiving unit may be used to perform reception-related operations (such as receiving data or messages), and the sending unit may be used to perform transmission-related operations (such as sending data or messages).

[0542] In a first possible design, the apparatus 1500 may be the first network element (e.g., session control network element) in the IMS in the aforementioned embodiment. The apparatus 1500 may implement the steps or processes corresponding to those performed by the first network element (e.g., session control network element) in the IMS in the aforementioned method embodiment. For example, the apparatus 1500 may implement the steps or processes corresponding to those performed by the session control network element in the method embodiment shown in FIG. 5 or FIG. 8 , or the apparatus 1500 may implement the steps or processes corresponding to those performed by the P-CSCF network element in the method embodiments shown in FIG. 6 , FIG. 7 , and FIG. 9 to FIG. 14 . The transceiver unit 1510 may be configured to perform transceiver-related operations (e.g., operations of sending and / or receiving data or messages) of the first network element (e.g., session control network element) in the IMS in the aforementioned method embodiment. The processing unit 1520 may be configured to perform processing-related operations of the first network element (e.g., session control network element) in the IMS in the aforementioned method embodiment, or operations other than transceiver operations (e.g., operations other than sending and / or receiving data or messages).

[0543] In one possible implementation, the transceiver unit 1510 is used to receive a first request message from a first terminal, where the first request message is used to request establishment of a session with a second terminal; the transceiver unit 1510 is also used to send a second request message to a first gateway in the IMS, where the second request message is used to request transmission resources, where the transmission resources are used to transmit media data between the first terminal and the second terminal, wherein the first gateway is deployed on a satellite, and both the first terminal and the second terminal are accessed via the satellite.

[0544] In a second possible design, the device 1500 may be a core network element in the aforementioned embodiment, and the device 1500 may implement the steps or processes executed by the core network element in the above method embodiment. For example, the device 1500 may implement the steps or processes executed by the core network element in the method embodiment shown in Figures 8 to 13 above. Among them, the transceiver unit 1510 may be used to perform operations related to transceiving of the core network element in the above method embodiment (such as operations of sending and / or receiving data or messages). The processing unit 1520 may be used to perform operations related to processing of the core network element in the above method embodiment, or operations other than transceiving (such as operations other than sending and / or receiving data or messages).

[0545] In one possible implementation, the transceiver unit 1510 is used to receive second indication information from a network element in the IMS, where the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground; the transceiver unit 1510 is also used to send a response message to the network element in the IMS, where the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the satellite, or the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the ground.

[0546] It should be understood that the specific process of each unit executing the above corresponding steps has been described in detail in the above method embodiment, and for the sake of brevity, it will not be repeated here.

[0547] It should also be understood that the device 1500 here is embodied in the form of a functional unit. The term "unit" here can refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combined logic circuit and / or other suitable components that support the described functions. In an optional example, those skilled in the art will understand that the device 1500 can be specifically the communication device in the above-mentioned embodiment, and can be used to execute the various processes and / or steps corresponding to the communication device in the above-mentioned method embodiments. To avoid repetition, they will not be described here.

[0548] The apparatus 1500 of each of the above-described solutions has the function of implementing the corresponding steps performed by the communication device in the above-described method. The functions can be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above-described functions; for example, the transceiver unit can be replaced by a transceiver (for example, the transmitting unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver), and other units, such as the processing unit, can be replaced by a processor to respectively perform the transceiver operations and related processing operations in each method embodiment.

[0549] In addition, the transceiver unit 1510 may also be a transceiver circuit (for example, may include a receiving circuit and a transmitting circuit), and the processing unit may be a processing circuit.

[0550] It should be noted that the device in Figure 15 can be a network element in the aforementioned embodiment, or it can be a chip or chip system, such as a system on chip (SoC). The transceiver unit can be an input / output circuit or a communication interface; the processing unit can be a processor, microprocessor, or integrated circuit integrated on the chip. This is not limited here.

[0551] Referring to FIG. 16 , FIG. 16 is a schematic diagram of another communication device 1600 provided in an embodiment of the present application. The device 1600 includes a processor 1610 coupled to a memory 1620. The memory 1620 is configured to store computer programs or instructions and / or data. The processor 1610 is configured to execute the computer programs or instructions stored in the memory 1620, or read data stored in the memory 1620, to perform the methods described in the above method embodiments.

[0552] Optionally, there are one or more processors 1610 .

[0553] Optionally, there are one or more memories 1620 .

[0554] Optionally, the memory 1620 is integrated with the processor 1610 or provided separately.

[0555] Optionally, as shown in Figure 16, the apparatus 1600 further includes a transceiver 1630, which is configured to receive and / or transmit signals. For example, the processor 1610 is configured to control the transceiver 1630 to receive and / or transmit signals.

[0556] As an example, the processor 1610 may have the function of the processing unit 1520 shown in FIG. 15 , the memory 1620 may have the function of a storage unit, and the transceiver 1630 may have the function of the transceiver unit 1510 shown in FIG. 15 .

[0557] As a solution, the device 1600 is used to implement the operations performed by the communication device in the above various method embodiments.

[0558] For example, the processor 1610 is configured to execute the computer program or instructions stored in the memory 1620 to implement relevant operations of the first network element (such as the session control network element (such as the P-CSCF network element)) in the IMS in the above various method embodiments.

[0559] For another example, the processor 1610 is configured to execute the computer program or instructions stored in the memory 1620 to implement the relevant operations of the core network element in the above various method embodiments.

[0560] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0561] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory and / or a non-volatile memory. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM). For example, RAM can be used as an external cache. By way of example and not limitation, RAM includes the following forms: static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0562] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) can be integrated into the processor.

[0563] It should also be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0564] 17 , which is a schematic diagram of a chip system 1700 according to an embodiment of the present application. The chip system 1700 (or also referred to as a processing system) includes a logic circuit 1710 and an input / output interface 1720 .

[0565] Logic circuit 1710 may be a processing circuit within chip system 1700. Logic circuit 1710 may be coupled to a storage unit and invoke instructions within the storage unit, enabling chip system 1700 to implement the methods and functions of various embodiments of the present application. Input / output interface 1720 may be an input / output circuit within chip system 1700, outputting information processed by chip system 1700 or inputting data or signaling information to be processed into chip system 1700 for processing.

[0566] Alternatively, the logic circuit 1710 may be implemented by one or more processors, including the one or more processors or a processing portion in the one or more processors.

[0567] Optionally, the input / output interface 1720 may include a transceiver circuit, a transceiver, an input / output circuit, or a communication interface.

[0568] As a solution, the chip system 1700 is used to implement the operations performed by the communication device (such as the network element in IMS (such as the session control network element, such as the first gateway), such as the core network network element, and such as the terminal device) in the above method embodiments.

[0569] For example, the logic circuit 1710 is used to implement the processing-related operations performed by the communication device (such as the network element in the IMS (such as the session control network element, such as the first gateway), such as the core network network element, and such as the terminal device) in the above method embodiment; the input / output interface 1720 is used to implement the sending and / or receiving-related operations performed by the communication device (such as the network element in the IMS (such as the session control network element, such as the first gateway), such as the core network network element, and such as the terminal device) in the above method embodiment.

[0570] An embodiment of the present application also provides a computer-readable storage medium on which computer instructions are stored for implementing the methods executed by a communication device (such as a network element in an IMS (such as a session control network element, such as a first gateway), such as a core network network element, and such as a terminal device) in the above-mentioned method embodiments.

[0571] For example, when the computer program is executed by a computer, the computer can implement the method performed by a communication device (such as a network element in an IMS (such as a session control network element, such as a first gateway), such as a core network network element, and such as a terminal device) in each embodiment of the above method.

[0572] An embodiment of the present application also provides a computer program product comprising instructions, which, when executed by a computer, implement the methods performed by a communication device (such as a network element in an IMS (such as a session control network element, such as a first gateway), such as a core network element, and such as a terminal device) in the above-mentioned method embodiments.

[0573] An embodiment of the present application further provides a communications system, comprising at least one of the session control network element, the first gateway, the core network element, and the terminal device described in the above embodiments. For example, the system comprises the terminal and the session control network element shown in FIG5 . For another example, the system comprises the IMS network element and the core network element shown in FIG8 . For another example, the system comprises at least one of the network elements shown in FIG6 , FIG7 , and FIG9 through FIG14 .

[0574] The explanation of the relevant contents and beneficial effects of any of the above-mentioned devices can be referred to the corresponding method embodiments provided above, which will not be repeated here.

[0575] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0576] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. For example, the computer can be a personal computer, a server, or a network device, etc. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state disk (SSD)). For example, the aforementioned available medium includes, but is not limited to, various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0577] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that, The method includes: A first network element in the Internet Protocol Multimedia Subsystem (IMS) receives a first request message from a first terminal, where the first request message is used to request to establish a session with a second terminal. The first network element in the IMS sends a second request message to a first gateway in the IMS, where the second request message is used to request transmission resources for transmitting media data between the first terminal and the second terminal. Herein, the first gateway is deployed on a satellite, and both the first terminal and the second terminal access through the satellite.

2. The method according to claim 1, wherein The media data between the first terminal and the second terminal does not pass through the gateway deployed on the ground in the IMS.

3. The method according to claim 1 or 2, characterized in that The first network element in the IMS sending the second request message to the first gateway in the IMS includes at least one of the following: When the first terminal accesses through the satellite, the first network element in the IMS sends the second request message to the first gateway in the IMS. Or According to the subscription information of the first terminal or when allowing the media data of the first terminal not to pass through the gateway deployed on the ground, the first network element in the IMS sends the second request message to the first gateway in the IMS, where the subscription information of the first terminal indicates that the media data of the first terminal is allowed not to pass through the ground and / or the first terminal accesses through the satellite.

4. The method according to claim 3, wherein The method further includes: The first network element in the IMS receives a registration request message from the first terminal, where the registration request message is used to request registration to the IMS. The first network element in the IMS sends the registration request message to a second network element in the IMS. The first network element in the IMS receives a registration response message from the second network element in the IMS, where the registration response message includes the subscription information of the first terminal.

5. The method according to claim 3 or 4, characterized in that, The first request message includes an access type, and the access type indicates that the terminal device accesses through the satellite.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: The first network element in the IMS sends a third request message to a second gateway in the IMS, where the third request message is used to request transmission resources for transmitting media data between the first terminal and the second terminal, and the second gateway is deployed on the ground.

7. The method according to claim 6, wherein The method further includes: Releasing the second gateway according to the first response message.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: The first network element in the IMS receives a first response message, and the first response message indicates that the media data between the first terminal and the second terminal does not pass through the gateway deployed on the ground.

9. The method according to any one of claims 1 to 5, characterized in that, At least one network element in the IMS is deployed in a visited network, and the at least one network element includes the first network element and a border control network element. At least one third network element in the IMS is deployed in a home network. The method further includes: The first network element in the IMS sends the first request message to the border control network element to request the border control network element to determine a gateway deployed on the ground for the first terminal.

10. The method according to any one of claims 1 to 9, characterized in that, At least one network element in the IMS is deployed in a visited network, the at least one network element includes the first network element, and at least one third network element in the IMS is deployed in a home network. The method further includes: The first network element in the IMS sends first indication information to a network element in the at least one third network element, and the first indication information indicates that media data between the first terminal and the second terminal performs visited network routing.

11. The method according to any one of claims 1 to 10, characterized in that, The method further includes: The first network element in the IMS sends second indication information to a network element in the first network, and the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground.

12. The method according to claim 11, wherein The first network element in the IMS sending the second indication information to a network element in the first network includes at least one of the following: When the first terminal accesses through a satellite, the first network element in the IMS sends the second indication information to a network element in the first network; According to the subscription information of the first terminal or when allowing the media data of the first terminal not to pass through the gateway deployed on the ground, the first network element in the IMS sends the second indication information to a network element in the first network, where the subscription information of the first terminal indicates that the media data of the first terminal is allowed not to pass through the ground and / or the first terminal accesses through a satellite; Or When the first terminal and the second terminal are served by the same policy control network element and / or session control network element, the first network element in the IMS sends the second indication information to a network element in the first network.

13. The method according to any one of claims 1 to 12, characterized in that, The method further includes: When the media data between the first terminal and the second terminal is transmitted through the first gateway, a second response message is sent to the first terminal, and the second response message includes the address of the first gateway.

14. The method according to any one of claims 1 to 13, characterized in that, The first terminal and the second terminal satisfy any one of the following: The first terminal and the second terminal are served by the same satellite; or, The first terminal and the second terminal are served by different satellites, and there is an inter-satellite link between the different satellites.

15. The method according to any one of claims 1 to 14, characterized in that, The first network element in the IMS is a session control network element in the IMS, and / or the first network element in the IMS is deployed on a satellite.

16. A communication method, characterized in that, The method includes: A network element in the first network receives second indication information from a network element in the IMS, and the second indication information indicates whether the media data between the first terminal and the second terminal passes through a gateway deployed on the ground; The network element in the first network sends a response message to the network element in the IMS, and the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on a satellite, or the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on the ground.

17. The method according to claim 16, wherein Both the first terminal and the second terminal access through satellites.

18. The method according to claim 16 or 17, wherein When the first terminal and the second terminal are served by the same policy control element, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on a satellite; or, When the first terminal and the second terminal are served by the same user plane element, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on a satellite; or, When there is an inter-satellite link between the first terminal and the second terminal, the response message indicates that the media data between the first terminal and the second terminal is transmitted by a gateway deployed on a satellite.

19. A communication method, characterized in that, The method includes: A first gateway in an Internet Protocol Multimedia Subsystem (IMS) receives media data from a first terminal; The first gateway in the IMS sends the media data to a second terminal via an inter-satellite link; wherein, the first gateway is deployed on a satellite, and both the first terminal and the second terminal access via the satellite.

20. The method according to claim 19, wherein Before the first gateway in the IMS receives media data from the first terminal, the method further includes: The first gateway in the IMS receives a second request message from a first element in the IMS, where the second request message is used to request transmission resources for transmitting media data between the first terminal device and the second terminal device.

21. A communication method, characterized in that, The method includes: A first element in an Internet Protocol Multimedia Subsystem (IMS) receives a first request message from a first terminal, where the first request message is used to request to establish a session with a second terminal; The first element in the IMS sends a second request message to a first gateway, where the second request message is used to request transmission resources for transmitting media data between the first terminal device and the second terminal device, wherein the first gateway is deployed on a satellite, and both the first terminal and the second terminal access via the satellite; In response to the second request message, the first gateway allocates the transmission resources for the media data between the first terminal device and the second terminal device.

22. A communication device, characterized in that, The device is deployed on a satellite and includes a first gateway in the IMS, where the first gateway is used to transmit media data between terminals accessing via the satellite.

23. The communication device according to claim 22, wherein, The device further includes a first element in the IMS, and the first element in the IMS communicates with the first gateway.

24. The communication device according to claim 22 or 23, characterized in that, The device further includes a user plane element in a first network, or, the device further includes: a user plane element in the first network and an access network element in the first network; Wherein, the terminal communicates with the first network through the user plane element and / or the access network element.

25. The communication device according to any one of claims 22 to 24, characterized in that, The first element in the IMS is used to execute the method according to any one of claims 1 to 15.

26. A communication device, characterized in that, Includes a module or unit for executing the method according to any one of claims 1 to 21.

27. A communication device, characterized in that, Comprising a processor, the processor is configured to execute a computer program or instructions in a memory to cause the device to perform the method according to any one of claims 1 to 21.

28. The device according to claim 27, characterized in that, The device further comprises the memory and / or a communication interface, the communication interface being coupled to the processor, the communication interface being configured to input and / or output information.

29. A computer-readable storage medium, characterized in that, A computer program or instructions is stored on the computer-readable storage medium, and when the computer program or instructions runs on a communication device, it causes the communication device to perform the method according to any one of claims 1 to 21.

30. A computer program product, characterized in that, The computer program product comprises a computer program or instructions for performing the method according to any one of claims 1 to 21.

31. A communication system, characterized in that, The communication system comprises a first gateway and a first network element in an Internet Protocol Multimedia Subsystem (IMS), the first network element in the IMS being configured to perform the method according to any one of claims 1 to 15.

32. The communication system according to claim 31, the communication system further comprising a network element in a first network, the network element in the first network being configured to perform the method according to any one of claims 16 to 18.

33. The communication system according to claim 31 or 32, wherein the communication system further comprises a user plane network element and / or an access network element in a first network, where The terminal communicates with the first network through the user plane network element and / or the access network element.

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