Communication method and communication device

Abstract

This application provides a communication method and a communication device. In the method, a relay terminal determines that a network accessed by the relay terminal supports an emergency service. The relay terminal transmits a first message, and the first message is used for a remote terminal to discover the relay terminal. The first message is a first discovery message, and the first discovery message includes a relay service code corresponding to the emergency service, or the first message is a response message, and the response message is used to respond to a second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to the emergency service. According to the above technical solution, it is ensured that the network accessed by the relay terminal participating in the relay discovery procedure of the emergency service supports the emergency service, and it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide a relay service for the emergency service. This facilitates the transmission of the emergency service in the relay scenario.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the priority of Chinese Patent Application No. 202210443631.5, titled "COMMUNICATION METHOD AND COMMUNICATION APPARATUS", filed with the China National Intellectual Property Administration on April 26, 2022, and incorporates its content by reference. [Technical Field] Embodiments of this application relate to the field of communications, and more specifically, to communication methods and communication apparatuses.

Background Art

[0002] With the rapid development of mobile communications, the wide use of new service types (such as data services like video chat and virtual reality (VR) / augmented reality (AR)) has increased users' bandwidth requirements. Device - to - device (D2D) communication enables direct communication between terminals, and the terminals may share spectrum resources with cell users under the control of the cell network, thus effectively improving the utilization of spectrum resources.

[0003] When a terminal is outside the coverage of the network or the communication signal between the terminal and the network is weak, the terminal may communicate with the network through the assistance of other terminals. Specifically, the communication between the terminal and the network is realized through D2D communication between the terminal and other terminals and communication between other terminals and the network. This communication scenario may be called a relay scenario. A terminal outside the coverage of the network or with a weak communication signal with the network may be called a remote terminal, and a terminal that assists the remote terminal when communicating with the network may be called a relay terminal.

[0004] Currently, emergency services are not considered in service transmission in a relay scenario. SUMMARY OF THE INVENTION

[0005] This application provides a communication method and a communication device for facilitating the transmission of emergency services in a relay scenario.

[0006] According to a first aspect, a communication method is provided. The method may be executed by a relay terminal, or may be executed by a module or unit within the relay terminal. For ease of explanation, hereinafter the relay terminal is used as a unified name.

[0007] The method includes the following. The relay terminal determines that a network accessed by the relay terminal supports emergency services. The relay terminal transmits a first message, and the first message is used for a remote terminal to discover the relay terminal. The first message is a first discovery message, and the first discovery message includes a relay service code corresponding to the emergency service, or the first message is a response message, and the response message is used to respond to a second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to the emergency service.

[0008] The emergency service here may be a general service type (which may also be called an emergency service type), or may be a specific emergency service.

[0009] According to the above technical solution, it is ensured that a network accessed by a relay terminal participating in the relay discovery procedure of an emergency service supports the emergency service, and it can be ensured that the relay terminal selected by a remote terminal expecting to access the emergency service can provide a relay service for the emergency service. This facilitates the transmission of emergency services in a relay scenario.

[0010] Optionally, the relay terminal transmitting the first message includes the following. When the network accessed by the relay terminal supports an emergency service, the relay terminal transmits the first message. Alternatively, in other description methods, after determining that the network accessed by the relay terminal supports an emergency service, the relay terminal transmits the first message.

[0011] In other words, when the network accessed by the relay terminal does not support an emergency service, the relay terminal does not participate in the relay discovery procedure for the emergency service, and only when the network accessed by the relay terminal supports an emergency service, the relay terminal may participate in the relay discovery procedure for the emergency service (for example, transmit a first discovery message to the remote terminal or respond to a second discovery message transmitted by the remote terminal). In this way, it can be ensured that the network accessed by the relay terminal participating in the relay discovery procedure for the emergency service supports the emergency service.

[0012] Optionally, before the relay terminal determines that the network accessed by the relay terminal supports an emergency service, the method further includes the following. The relay terminal determines that the first message includes a relay service code corresponding to the emergency service.

[0013] In other words, if the relay service code included in the first message corresponds to an emergency service, the relay terminal may determine whether the network accessed by the relay terminal supports the emergency service. If the relay service code included in the first message does not correspond to an emergency service, the relay terminal may not determine whether the network accessed by the relay terminal supports the emergency service.

[0014] Referring to the first aspect, in a possible implementation manner, for the relay terminal to determine that the network accessed by the relay terminal supports emergency services includes the following. When at least one of the following cases is satisfied, the relay terminal determines that the network accessed by the relay terminal supports emergency services. The relay terminal has received an emergency service support indicator from an access and mobility management function network element or an access network device, or the relay terminal has stored an emergency service support indicator, or the relay terminal has established an emergency protocol data unit (PDU) session. The emergency service support indicator indicates that the network accessed by the relay terminal supports emergency services.

[0015] Referring to any one of the first aspect or the implementation manner of the first aspect, in another possible implementation manner, the relay terminal is in an emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicates that the relay terminal is in an emergency registration state, and the emergency registration time information indicates the time or remaining time when the relay terminal is in an emergency registration state.

[0016] The above technical solution helps the remote terminal select a more appropriate relay terminal. For example, the remote terminal preferentially selects a relay terminal in a non-emergency registration state. In another example, when all relay terminals that send discovery messages or response messages are in an emergency registration state, the remote terminal preferentially selects a relay terminal with a longer remaining time in the emergency registration state.

[0017] Referring to any one of the first aspect or the implementation manner of the first aspect, in another possible implementation manner, the method includes the following. The relay terminal receives first configuration information from a policy control function network element, and the first configuration information includes a relay service code corresponding to an emergency service.

[0018] In other words, the policy control function network element configures a relay service code for emergency services for the relay terminal.

[0019] Referring to either the first aspect or any one of the implementation manners of the first aspect, in other possible implementation manners, the first configuration information further includes the priority of the relay service code corresponding to the emergency service, and the method further includes the following. The relay terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority, and the connection is used for the transmission of the emergency service.

[0020] For example, the policy control function network element uses the first configuration information to configure, for the relay terminal, a plurality of relay service codes including the relay service code corresponding to the emergency service, and the priority of each of the plurality of relay service codes. The relay terminal establishes a plurality of connections to the remote terminal, and the plurality of connections have a one-to-one correspondence with the plurality of relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), and connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the relay terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the relay terminal are limited, the relay terminal may release the connection with the lower priority of the relay service code from the plurality of established connections.

[0021] The above technical solution helps the relay terminal to perform connection management.

[0022] Referring to either the first aspect or one of the implementation manners of the first aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a direct communication request message directly from the remote terminal. The direct communication request message is used to request the establishment of a direct communication connection, and the direct communication connection is used for the transmission of emergency services. The relay terminal sends a second message to the access and mobility management function network element. The second message is used to request the authorization for the remote terminal to access emergency services. The relay terminal receives an authorization result from the access and mobility management function network element. If the authorization result indicates that the remote terminal has successfully obtained authorization to access emergency services, the relay terminal sends a direct communication acceptance message to the remote terminal. Or, if the authorization result indicates that the remote terminal has failed to obtain authorization to access emergency services, the relay terminal sends a direct communication rejection message to the remote terminal.

[0023] According to the above technical solution, in the procedure of establishing a connection to the remote terminal, the relay terminal determines whether the network authorizes the remote terminal to access emergency services. The relay terminal establishes a connection to the remote terminal and provides a relay service for emergency services to the remote terminal only when the remote terminal is authorized to access emergency services. In this way, it can be ensured that the relay terminal selected by the remote terminal expecting to access emergency services can provide a relay service for emergency services, and access by unauthorized remote terminals to emergency services can be avoided.

[0024] Referring to either the first aspect or one of the implementation manners of the first aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a second discovery message from the remote terminal. The relay terminal sends the second message to the access and mobility management function network element, and the second message is used to request authorization for the remote terminal to access the emergency service. The relay terminal receives an authorization result from the access and mobility management function network element. The relay terminal's determination that the network accessed by the relay terminal supports the emergency service includes the following. When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the relay terminal determines that the network accessed by the relay terminal supports the emergency service.

[0025] In the above technical solution, after receiving the second discovery message of the remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access the emergency service. When the network normally authorizes the remote terminal to access the emergency service, the relay terminal further determines whether the network accessed by the relay terminal supports the emergency service. Then, depending on whether the network accessed by the relay terminal supports the emergency service, the relay terminal sends or does not send a response message to the second discovery message. In this way, it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide a relay service for the emergency service, and unauthorized access of the remote terminal to the emergency service can be avoided.

[0026] Referring to either the first aspect or any one of the implementation manners of the first aspect, in other possible implementation manners, before the relay terminal determines that the network accessed by the relay terminal supports the emergency service, the method further includes the following. The relay terminal receives a second discovery message from the remote terminal. After the relay terminal determines that the network accessed by the relay terminal supports the emergency service, the method further includes the following. The relay terminal sends a second message to the access and mobility management function network element, and the second message is used to request to authorize the remote terminal to access the emergency service. The relay terminal receives an authorization result from the access and mobility management function network element. The relay terminal sending the first message includes the following. When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the relay terminal sends a response message to the remote terminal.

[0027] In the above technical solution, after receiving the second discovery message of the remote terminal, the relay terminal first determines whether the network accessed by the relay terminal supports the emergency service. When the network accessed by the relay terminal supports the emergency service, the relay terminal further determines whether the network authorizes the remote terminal to access the emergency service. Then, depending on whether the network authorizes the remote terminal to access the emergency service, the relay terminal sends or does not send a response message to the second discovery message. In this way, it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide a relay service for the emergency service, and unauthorized access of the remote terminal to the emergency service can be avoided.

[0028] Referring to either the first aspect or one of the implementation manners of the first aspect, in other possible implementation manners, the method includes the following. The relay terminal transmits first information to an access and mobility management function network element, where the first information indicates that the relay service of the relay terminal is used for an emergency service, or the first information indicates that the relay terminal provides an emergency service to a remote terminal.

[0029] In other words, the relay terminal reports to the access and mobility management function network element that the relay terminal is in a state of providing a relay service for an emergency service or the relay terminal is in a state of providing an emergency service to a remote terminal, so that as a result, the access and mobility management function network element does not restrict the relay terminal regarding access management or mobility management. For example, the relay terminal may provide a relay service to a remote terminal within an unauthorized area.

[0030] Optionally, after receiving the first information, the access and mobility management function network element stores the first information in the context of the relay terminal.

[0031] Optionally, the first information may be carried in a service request message, a PDU session establishment message, or a registration message.

[0032] Optionally, when the PDU session establishment message carries the first piece of information, the first piece of information indicates that the PDU session is used for the transmission of emergency services. In this case, the access and mobility management function network element selects a session management function network element that can provide emergency services based on the first piece of information, or the access and mobility management function network element sends the first piece of information to the session management function network element. When the access and mobility management function network element sends the first piece of information to the session management function network element, the session management function network element selects a user plane function network element that can provide emergency services based on the first piece of information.

[0033] Referring to either the first aspect or any one of the implementation manners of the first aspect, in other possible implementation manners, the method further includes the following. The relay terminal sends the second piece of information to the access and mobility management function network element, and the second piece of information indicates that the relay terminal's providing emergency services to the remote terminal is cancelled, or the second piece of information indicates that the relay terminal does not provide emergency services to the remote terminal.

[0034] In other words, the relay terminal reports to the access and mobility management function network element that the relay terminal is not in a state of providing relay services for emergency services or that the relay terminal is not in a state of providing emergency services to the remote terminal, so that the access and mobility management function network element restricts the relay terminal regarding access management or mobility management.

[0035] Optionally, after receiving the second piece of information, the access and mobility management function network element deletes the first piece of information from the context of the relay terminal.

[0036] Optionally, the relay terminal accessing and transmitting the second information to the access and mobility management function network element includes the following. After the relay terminal releases the connection used for the transmission of the emergency service, the relay terminal either transmits the second information to the access and mobility management function network element, or if the relay terminal no longer has the connection used for the transmission of the emergency service, the relay terminal transmits the second information to the access and mobility management function network element.

[0037] Referring to either the first aspect or any one of the implementation manners of the first aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a seventh message from the remote terminal, and the seventh message is used to request to establish a connection to the relay terminal, and the connection is used for the transmission of the emergency service. After receiving the seventh message, if the relay terminal does not have an emergency PDU session, the relay terminal requests to establish an emergency PDU session. Further, if the relay terminal has established an emergency PDU session, the relay terminal may not request to establish an emergency PDU session.

[0038] Optionally, the connection is a direct communication connection, and the seventh message is a direct communication request message.

[0039] According to a second aspect, a communication method is provided. The method may be executed by a policy control function network element, or may be executed by a module or unit within the policy control function network element. For the sake of easy explanation, hereinafter the policy control function network element is used as a unified name.

[0040] The method includes the following. The policy control function network element obtains a relay service code corresponding to the emergency service. The policy control function network element transmits first configuration information to the relay terminal, and the first configuration information includes a relay service code corresponding to the emergency service.

[0041] The emergency service here may be a general service type (which may also be called an emergency service type), or a specific emergency service.

[0042] In the above technical solution, the policy control function network element configures a relay service code corresponding to the emergency service for the relay terminal, so that the relay terminal can participate in the relay discovery procedure of the emergency service and facilitate the transmission of the emergency service in the relay scenario.

[0043] Referring to the second aspect, in a possible implementation manner, the first configuration information further includes the priority of the relay service code corresponding to the emergency service.

[0044] The above technical solution helps the relay terminal to perform connection management. For example, the policy control function network element uses the first configuration information to configure, for the relay terminal, a plurality of relay service codes including the relay service code corresponding to the emergency service and the priority of each of the plurality of relay service codes. The relay terminal establishes a plurality of connections to the remote terminal, and the plurality of connections have a one-to-one correspondence with the plurality of relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), and connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the relay terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the relay terminal are limited, the relay terminal may release the connection with a lower priority of the relay service code from the plurality of established connections.

[0045] Referring to either the second aspect or any one of the implementation manners of the second aspect, in other possible implementation manners, the policy control function network element sending the first configuration information to the relay terminal includes the following. When the network accessed by the relay terminal supports an emergency service, the policy control function network element sends the first configuration information to the relay terminal.

[0046] According to the above technical solution, the policy control function network element provides the relay service code corresponding to the emergency service to the relay terminal only when the network accessed by the relay terminal supports the emergency service. In other words, when the network accessed by the relay terminal does not support the emergency service, the policy control function network element does not provide the relay service code corresponding to the emergency service to the relay terminal. Therefore, the relay terminal does not participate in the relay discovery procedure for the emergency service. In this way, it is ensured that the network accessed by the relay terminal participating in the relay discovery procedure for the emergency service supports the emergency service, and it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide the relay service for the emergency service. This facilitates the transmission of the emergency service in the relay scenario.

[0047] Referring to either the second aspect or any one of the implementation manners of the second aspect, in other possible implementation manners, the method further includes the following. When at least one of the following cases is satisfied, the policy control function network element determines that the network accessed by the relay terminal supports the emergency service. The policy control function network element has received an emergency service support indicator from the access and mobility management function network element, or the policy control function network element stores or pre-configures the emergency service support indicator. The emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service.

[0048] Referring to either the second aspect or any one of the implementation manners of the second aspect, in other possible implementation manners, the method further includes the following. The policy control function network element sends second configuration information to the remote terminal, and the second configuration information includes a relay service code corresponding to the emergency service.

[0049] In other words, the policy control function network element configures a relay service code corresponding to the emergency service for the remote terminal.

[0050] Referring to either the second aspect or any one of the implementation manners of the second aspect, in other possible implementation manners, the second configuration information further includes the priority of the relay service code corresponding to the emergency service.

[0051] The above technical solution is helpful for the remote terminal to perform connection management. For example, the policy control function network element configures, for the remote terminal, by using the second configuration information, a plurality of relay service codes including a relay service code corresponding to the emergency service, and the priority of each of the plurality of relay service codes. The remote terminal establishes a plurality of connections to the relay terminal, and the plurality of connections have a one-to-one correspondence with the plurality of relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), and connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the remote terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the remote terminal are limited, the remote terminal may release the connections with a lower priority of the relay service code from the plurality of established connections.

[0052] Referring to either the second aspect or one of the implementation manners of the second aspect, in other possible implementation manners, for the policy control function network element to obtain the relay service code corresponding to the emergency service includes the following. The policy control function network element obtains the relay service code corresponding to the emergency service from the application function network element.

[0053] According to the above technical solution, it can be ensured that the relay service codes of different public land mobile networks (PLMNs) are consistent. Therefore, the inter-PLMN relay service used for emergency services can be better supported.

[0054] According to the third aspect, a communication method is provided. The method may be executed by a remote terminal, or may be executed by a module or unit within the remote terminal. For the sake of easy explanation, hereinafter the remote terminal is used as a unified name.

[0055] The method includes the following. The remote terminal receives a first message from a first relay terminal, and the first message is used by the remote terminal to discover the first relay terminal. The first message includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the first relay terminal is in an emergency registration state, and the emergency registration time information indicates the time or remaining time when the first relay terminal is in an emergency registration state. The remote terminal selects a relay terminal based on the first message. The first message is a first discovery message, and the first discovery message includes a relay service code corresponding to the emergency service, or the first message is a response message, and the response message is used to respond to a second discovery message sent by the remote terminal. The second discovery message includes a relay service code corresponding to the emergency service.

[0056] The above technical solution helps the remote terminal select a more appropriate relay terminal and facilitates the transmission of emergency services in the relay scenario. For example, the remote terminal preferentially selects a relay terminal in a non-emergency registration state. In another example, when all relay terminals that send discovery messages or response messages are in an emergency registration state, the remote terminal preferentially selects a relay terminal with a longer remaining time in the emergency registration state.

[0057] Referring to the third aspect, in a possible implementation manner, the method further includes the following. The remote terminal receives second configuration information from a policy control function network element, and the second configuration information includes a relay service code corresponding to an emergency service.

[0058] In other words, the policy control function network element configures a relay service code corresponding to an emergency service for the remote terminal.

[0059] Referring to any one of the third aspect or the implementation manner of the third aspect, in another possible implementation manner, the second configuration information further includes the priority of the relay service code corresponding to the emergency service, and the method further includes the following. The remote terminal maintains or releases the connection between the remote terminal and the relay terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service.

[0060] For example, the policy control function network element configures, for the remote terminal, a plurality of relay service codes including an emergency service relay service code and the priority of each of the plurality of relay service codes by using the second configuration information. The remote terminal establishes a plurality of connections to the relay terminal, and the plurality of connections have a one-to-one correspondence with the plurality of relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), and connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the remote terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the remote terminal are limited, the remote terminal may release the connections with a lower priority of the relay service codes from the plurality of established connections.

[0061] The above technical solution helps the remote terminal to perform connection management.

[0062] According to a fourth aspect, a communication method is provided. The method may be executed by a relay terminal, or may be executed by a module or unit in the relay terminal. For ease of explanation, hereinafter the relay terminal is used as a unified name.

[0063] The method includes the following. The relay terminal generates a first message. The relay terminal is in an emergency registration state. The first message includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the relay terminal is in an emergency registration state. The emergency registration time information indicates the time or remaining time that the relay terminal is in an emergency registration state. The relay terminal transmits the first message, and the first message is used for the remote terminal to discover the relay terminal. The first message is a first discovery message, and the first discovery message includes a relay service code corresponding to an emergency service. Or the first message is a response message, and the response message is used to respond to a second discovery message from the remote terminal. The second discovery message includes a relay service code corresponding to an emergency service.

[0064] The above technical solution helps the remote terminal select a more appropriate relay terminal and facilitates the transmission of emergency services in a relay scenario. For example, the remote terminal preferentially selects a relay terminal in a non-emergency registration state. In another example, when all relay terminals that transmit discovery messages or response messages are in an emergency registration state, the remote terminal preferentially selects a relay terminal with a longer remaining time in the emergency registration state.

[0065] Referring to the fourth aspect, in a possible implementation manner, the method further includes the following. The relay terminal receives first configuration information from a policy control function network element, and the first configuration information includes a relay service code corresponding to an emergency service.

[0066] In other words, the policy control function network element configures a relay service code corresponding to an emergency service for the relay terminal.

[0067] Referring to either the fourth aspect or the implementation manner of the fourth aspect, in other possible implementation manners, the first configuration information further includes the priority of the relay service code corresponding to the emergency service, and the method further includes the following. The relay terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service.

[0068] For example, the policy control function network element constructs, for the relay terminal, a plurality of relay service codes including the relay service code corresponding to the emergency service and the priority of each of the plurality of relay service codes by using the first configuration information. The relay terminal establishes a plurality of connections to the remote terminal, and the plurality of connections have a one-to-one correspondence with the plurality of relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), and connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the relay terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the relay terminal are limited, the relay terminal may release the connections with a lower priority of the relay service code from the plurality of established connections.

[0069] The above technical solution is helpful for the relay terminal to perform connection management.

[0070] Referring to either the fourth aspect or one of the implementation manners of the fourth aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a direct communication request message directly from the remote terminal. The direct communication request message is used to request to establish a direct communication connection, and the direct communication connection is used for the transmission of emergency services. The relay terminal sends a second message to the access and mobility management function network element. The second message is used to request the access and mobility management function network element to authorize the remote terminal to access emergency services. The relay terminal receives an authorization result from the access and mobility management function network element. If the authorization result indicates that the remote terminal has successfully been authorized to access emergency services, the relay terminal sends a direct communication acceptance message to the remote terminal. Or, if the authorization result indicates that the remote terminal has failed to be authorized to access emergency services, the relay terminal sends a direct communication rejection message to the remote terminal.

[0071] According to the above technical solution, in the procedure of establishing a connection to the remote terminal, the relay terminal determines whether the network authorizes the remote terminal to access emergency services. The relay terminal establishes a connection to the remote terminal and provides a relay service for emergency services to the remote terminal only when the remote terminal is authorized to access emergency services. This helps to avoid the access of unauthorized remote terminals to emergency services.

[0072] Referring to either the fourth aspect or one of the implementation manners of the fourth aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a second discovery message from the remote terminal. The relay terminal sends the second message to the access and mobility management function network element, and the second message is used to request authorization for the remote terminal to access the emergency service. The relay terminal receives an authorization result from the access and mobility management function network element. The relay terminal sending the first message includes the following. When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the relay terminal sends a response message to the remote terminal.

[0073] In the above technical solution, after receiving the second discovery message of the remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access the emergency service. When the network successfully authorizes the remote terminal to access the emergency service, the relay terminal sends a response message to the second discovery message. This helps to avoid unauthorized access of the remote terminal to the emergency service.

[0074] Referring to either the fourth aspect or one of the implementation manners of the fourth aspect, in other possible implementation manners, the method includes the following. The relay terminal sends first information to the access and mobility management function network element, where the first information indicates that the relay service of the relay terminal is used for the emergency service, or the first information indicates that the relay terminal provides the emergency service to the remote terminal.

[0075] In other words, the relay terminal reports to the access and mobility management function network element that it is in a state of providing a relay service for an emergency service or a state of providing an emergency service to a remote terminal, and as a result, the access and mobility management function network element refrains from restricting the relay terminal regarding access management or mobility management. For example, the relay terminal may provide a relay service within an unauthorized area.

[0076] Optionally, after receiving the first information, the access and mobility management function network element stores the first information in the context of the relay terminal.

[0077] Optionally, the first information may be carried in a service request message, a PDU session establishment message, or a registration message.

[0078] Optionally, when the PDU session establishment message carries the first information, the first information indicates that the PDU session is used for the transmission of an emergency service. In this case, the access and mobility management function network element selects a session management function network element capable of providing an emergency service based on the first information, or the access and mobility management function network element transmits the first information to the session management function network element. When the access and mobility management function network element transmits the first information to the session management function network element, the session management function network element selects a user plane function network element capable of providing an emergency service based on the first information.

[0079] Referring to either the fourth aspect or any one of the implementation manners of the fourth aspect, in other possible implementation manners, the method further includes the following. The relay terminal sends the second information to the access and mobility management function network element, where the second information indicates that the relay terminal is canceled from providing emergency services to the remote terminal, or the second information indicates that the relay terminal does not provide emergency services to the remote terminal.

[0080] In other words, the relay terminal reports to the access and mobility management function network element that the relay terminal is not in a state of providing a relay service for emergency services or that the relay terminal is in a state of not providing emergency services to the remote terminal, so that as a result, the access and mobility management function network element restricts the relay terminal regarding access management or mobility management.

[0081] Optionally, after receiving the second information, the access and mobility management function network element deletes the first information from the context of the relay terminal.

[0082] Optionally, the relay terminal sending the second information to the access and mobility management function network element includes the following. After the relay terminal releases the connection used for the transmission of emergency services, the relay terminal sends the second information to the access and mobility management function network element, or if the relay terminal no longer has the connection used for the transmission of emergency services, the relay terminal sends the second information to the access and mobility management function network element.

[0083] Referring to either the fourth aspect or one of the implementation manners of the fourth aspect, in other possible implementation manners, the method further includes the following. The relay terminal receives a seventh message from the remote terminal, and the seventh message is used to request to establish a connection to the relay terminal, and the connection is used for the transmission of emergency services. After receiving the seventh message, if the relay terminal does not have an emergency PDU session, the relay terminal requests to establish an emergency PDU session. Further, if the relay terminal has established an emergency PDU session, the relay terminal may not need to request to establish an emergency PDU session.

[0084] Optionally, the connection is a direct communication connection, and the seventh message is a direct communication request message.

[0085] According to a fifth aspect, a communication method is provided. The method may be executed by an application function network element, or may be executed by a module or unit within the application function network element. For the sake of easy explanation, hereinafter, the application function network element is used as a unified name.

[0086] The method includes the following. The application function network element determines a relay service code corresponding to the emergency service. The application function network element transmits the relay service code corresponding to the emergency service to the policy control function network element.

[0087] According to the above technical solution, it can be ensured that the relay service codes of different PLMNs are consistent. Therefore, the PLMN - to - PLMN relay service used for emergency services can be better supported.

[0088] According to the sixth aspect, a communication device is provided. The device is configured to execute the method provided in any one of the above aspects or the implementation manners of the above aspects. Specifically, the device may include a unit and / or a module configured to execute the method provided in any one of the above aspects or the implementation manners of the above aspects, for example, a processing unit and / or a communication unit.

[0089] In the implementation manner, the device is a relay terminal, a policy control function network element, a remote terminal, or an application function network element. When the device is a relay terminal, a policy control function network element, a remote terminal, or an application function network element, the communication unit may be a transceiver, an input / output interface, or a communication interface, and the processing unit may be at least one processor. Optionally, the transceiver is a transceiver circuit. Optionally, the input / output interface is an input / output circuit.

[0090] In another implementation manner, the device is a chip, a chip system, or a circuit used in a relay terminal, a policy control function network element, a remote terminal, or an application function network element. When the device is a chip, a chip system, or a circuit used in a relay terminal, a policy control function network element, a remote terminal, or an application function network element, the communication unit may be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, a related circuit, etc. on the chip, the chip system, or the circuit, and the processing unit may be at least one processor, a processing circuit, a logic circuit, etc.

[0091] According to a seventh aspect, a communication device is provided. The device includes a memory configured to store a program, and at least one processor configured to execute a computer program or instruction stored in the memory to execute the method provided in any one of the above aspects or the implementation manner of the above aspect.

[0092] In an implementation manner, the device is a relay terminal, a policy control function network element, a remote terminal, or an application function network element.

[0093] In another implementation manner, the device is a chip, a chip system, or a circuit used in a relay terminal, a policy control function network element, a remote terminal, or an application function network element.

[0094] According to an eighth aspect, a communication device is provided. The device includes at least one processor and a communication interface. The at least one processor is configured to obtain a computer program or instruction stored in a memory through the communication interface and execute the method provided in any one of the above aspects or the implementation manner of the above aspect. The communication interface may be implemented by hardware or software.

[0095] In an implementation manner, the device further includes a memory.

[0096] According to a ninth aspect, a processor is provided and configured to execute the method provided in the above aspect.

[0097] Operations such as transmission and acquisition / reception related to the processor may be understood as operations such as the output and reception or input of the processor, or as operations such as transmission and reception performed by the radio frequency circuit and the antenna, unless otherwise specified or unless the operations conflict with the actual functions or internal logic of the operations in the related description. This is not limited in this application.

[0098] According to a tenth aspect, a computer-readable storage medium is provided. The computer-readable medium stores program code to be executed by a device, and the program code is used to execute the method provided in any one of the above aspects or the implementation manner of the above aspects.

[0099] According to an eleventh aspect, a computer program product including instructions is provided. When the computer program product is executed on a computer, the computer can execute the method provided in any one of the above aspects or the implementation manner of the above aspects.

[0100] According to a twelfth aspect, a chip is provided. The chip includes a processor and a communication interface. The processor reads instructions stored in the memory through the communication interface and executes the method provided in any one of the above aspects or the implementation manner of the above aspects. The communication interface may be implemented by hardware or software.

[0101] Optionally, in the implementation manner, the chip further includes a memory. The memory stores a computer program or instructions. The processor is configured to execute the computer program or instructions stored in the memory. When the computer program or instructions are executed, the processor is configured to execute the method provided in any one of the above aspects or the implementation manner of the above aspects.

[0102] According to the 13th aspect, a communication system is provided, including at least one of the relay terminal, policy control function network element, remote terminal, or application function network element described above.

Brief Description of the Drawings

[0103]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

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

[0105] To facilitate the understanding of the embodiments of this application, the following explanations are provided first before the embodiments of this application are described.

[0106] In this application, "indicating" may include directly indicating and indirectly indicating, or "indicating" may be explicitly and / or implicitly indicating. For example, when a piece of information is described as indicating information I, the information may directly indicate I or may indirectly indicate I, but this does not mean that the information clearly conveys I. In other examples, implicit indication may be based on the position and / or resources used for transmission, and explicit indication may be based on one or more parameters, one or more indexes, and / or one or more bit patterns represented by the information.

[0107] The definitions listed for many features in this application are used merely by way of example to explain the functions of the features. For details of the definitions, refer to the prior art.

[0108] In the following embodiments, the first, second, third, fourth, and various numbers are used merely for the purpose of easy distinction for explanation and are not used to limit the scope of the embodiments of this application. For example, they are used for distinction between different fields and different information.

[0109] "Pre - definition" may be realized by pre - storing the corresponding code or table in a device (including, for example, a terminal or a network device), or may be realized in other ways that can indicate relevant information. The specific realization method of pre - definition is not limited in this application. "Storage" may be storage in one or more memories. The type of memory may be any form of storage medium. This is not limited in this application.

[0110] The "protocol" in the embodiments of this application may be a standard protocol in the field of communication. For example, it may include the Long Term Evolution (LTE) protocol, the New Radio (NR) protocol, and related protocols applicable to future communication systems. This is not limited in this application.

[0111] Aspects, embodiments, or features are presented in this application by describing systems that include multiple devices, components, modules, etc. It should be recognized and understood that each system may include other devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. discussed with reference to the accompanying drawings. Furthermore, combinations of these solutions may be used.

[0112] In the embodiments of this application, words such as "example" or "for example" are used to represent giving an example, illustration, or explanation. Any embodiment or design approach described as an "example" in this application should not be described as being more preferred or having more advantages than other embodiments or design approaches. Exactly, the use of the word "example" is intended to present a concept in a specific way.

[0113] The terms "comprising", "having", and their variants mean "including but not limited to" unless otherwise emphasized.

[0114] "At least one" means one or more, and "a plurality" means two or more. "And / or" describes the associative relationship between related objects and indicates that three relationships can exist. For example, A and / or B may represent the following cases, namely, only A exists, both A and B exist, and only B exists, and A and B may be singular or plural. The character " / " usually indicates an "or" relationship between related objects. "At least one of the following items" or similar expressions mean any combination of these items and include any combination of a single item or multiple items. For example, at least one of a, b, and c may represent a, b, c, a and b, a and c, b and c, or a, b, and c. Each of a, b, and c may be singular or plural.

[0115] The technical solutions provided in this application may be applied to various communication systems, such as the 5th generation (5G) or NR system, LTE system, LTE frequency division duplex (FDD) system, and LTE time division duplex (TDD) system. The technical solutions provided in this application may further be applied to non-terrestrial network (NTN) communication systems such as satellite communication systems. The technical solutions provided in this application may further be applied to device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, machine-to-machine (M2M) communication, machine type communication (MTC), internet of things (IoT) communication systems, or other communication systems. The technical solutions provided in this application may further be applied to future communication systems, such as the 6th generation mobile communication system.

[0116] In one example, FIG. 1 is a diagram of a network architecture.

[0117] As shown in FIG. 1, a 5G system (5th generation system, 5GS) is used as an example of a network architecture. The network architecture may include three parts, namely, a user equipment (UE) part, a data network (DN) part, and an operator network part. The operator network may include one or more of the following network elements, namely, a (radio) access network ((R)AN) device, a user plane function (UPF) network element, an authentication server function (AUSF) network element, an access and mobility management function (AMF) network element, a session management function (SMF) network element, a network slice selection function (NSSF) network element, a network exposure function (NEF) network element, a network repository function (NRF) network element, a policy control function (PCF) network element, a unified data management (UDM) network element, and an application function (AF) network element. In the above operator network, the parts other than the RAN part may be referred to as the core network part.

[0118] In this application, the user equipment, (radio) access network device, UPF network element, AUSF network element, AMF network element, SMF network element, NSSF network element, NEF network element, NRF network element, PCF network element, UDM network element, and AF network element are respectively abbreviated as UE, (R)AN, UPF, AUSF, UDR, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, and AF for short.

[0119] The UE, (R)AN, UPF, and DN in FIG. 1 are generally referred to as data plane network functions or entities. The transmission of UE data may be performed by using a PDU session established between the UE and the DN. The network elements in FIG. 1 are briefly described below.

[0120] 1. UE

[0121] The UE in this application may also be referred to as a terminal, user, access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal device, wireless communication device, user agent, user equipment, etc. For the sake of simplicity in description, the terminal is used as a unified name hereinafter.

[0122] A terminal is a device that can access a network. The terminal and the (R)AN may communicate with each other by using air interface technology (e.g., NR or LTE technology). Terminals may also communicate with each other by using air interface technology (e.g., NR or LTE technology). The terminal may be a mobile phone, a pad, a computer with a wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a terminal in satellite communication, a terminal in an integrated access and backhaul (IAB) link system, a terminal in a Wi-Fi communication system, a terminal in industrial control, a terminal in self-driving, a terminal in remote medical, a terminal in a smart grid, a terminal in transportation safety, a terminal in a smart city, a terminal in a smart home, etc.

[0123] The specific technology and specific device form used by the UE are not limited in this embodiment of this application.

[0124] 2. (R)AN

[0125] The (R)AN in this application may be a device configured to communicate with a terminal, or may be a device that connects a terminal to a wireless network.

[0126] (R)AN may be a node in a radio access network. (R)AN may be a base station, evolved NodeB (eNodeB), transmission reception point (TRP), home base station (e.g., home evolved NodeB or home NodeB, HNB), Wi-Fi access point (AP), mobile switching center, next generation NodeB (gNB) in a 5G mobile communication system, next generation NodeB in a 6th generation (6G) mobile communication system, base station in a future mobile communication system, etc. Alternatively, the network device may be a module or unit that completes some functions of the base station, e.g., a central unit (CU), a distributed unit (DU), a remote radio unit (RRU), or a baseband unit (BBU). Alternatively, (R)AN may be a device that undertakes the base station function in a D2D communication system, a V2X communication system, an M2M communication system, and an IoT communication system. Alternatively, (R)AN may be a network device in an NTN. In other words, (R)AN may be deployed on a high-altitude platform or a satellite. (R)AN may be a macro base station, a micro base station or an indoor base station, or a relay node, a donor node, etc.

[0127] The specific technologies, device forms, and names used by (R)AN are not limited in the embodiments of this application. For ease of explanation, the access network device is used as the unified name of (R)AN hereinafter.

[0128] 3. UPF

[0129] The UPF is mainly responsible for the transfer and reception of user data at the terminal. For example, the UPF may receive user plane data from the DN and transmit the user plane data to the terminal via the access network device. The UPF may further receive user plane data from the terminal via the access network device and transfer the user plane data to the DN. The transmission resources and scheduling functions used by the UPF network element to provide services to the terminal are managed and controlled by the SMF.

[0130] 4.DN

[0131] The DN is mainly used as an operator network that provides data services to the terminal, such as the Internet, a third-party service network, or an IP multimedia service (IMS) network.

[0132] 5.AUSF

[0133] 3rd generation partnership project (3GPP) and non-3GPP access authentication are supported.

[0134] 6.AMF

[0135] The AMF is mainly responsible for signaling processing, such as functions like access control, mobility management, attach and detach, and gateway selection. When providing services for a session at the terminal, the AMF provides control plane storage resources for the session and stores session identifiers, SMF network element identifiers associated with the session identifiers, etc.

[0136] 7.SMF

[0137] The SMF is mainly responsible for user plane network element selection, user plane network element redirection, Internet Protocol (IP) address allocation, bearer establishment, modification and release, quality of service (QoS) control, etc.

[0138] 8. NSSF

[0139] The NSSF is mainly responsible for network slice selection and determines the network slice instances to which the terminal is permitted to access based on the slice selection assistance information of the terminal, subscription information, etc.

[0140] 9. NEF

[0141] The NEF mainly supports secure interactions between the 3GPP network and third-party applications.

[0142] 10. NRF

[0143] The NRF is mainly configured to store network function entities, description information of services provided by network function entities, etc.

[0144] 11. PCF

[0145] The PCF is mainly responsible for policy control decisions, providing policy rules for control plane functions, traffic-based charging control functions, etc.

[0146] 12. UDM

[0147] The UDM is mainly responsible for subscription data management of the terminal, including storage and management of terminal identifiers, access permission of the terminal, etc.

[0148] 13. AF

[0149] The AF mainly supports interacting with the 3GPP core network to provide services, for example, influencing data routing decisions, providing policy control functions, or providing third-party services for the network. The AF may be an AF deployed in the operator network or a third-party AF.

[0150] In the network architecture shown in FIG. 1, network elements may communicate with each other through interfaces. The interfaces between network elements may be point-to-point interfaces or service-based interfaces. This is not limited in this application.

[0151] It should be understood that the network architecture shown above is merely an example for explanation, and the network architectures applicable to the embodiments of this application are not limited thereto. Any network architecture capable of implementing the functions of the above network elements is applicable to the embodiments of this application.

[0152] The functions or network elements such as AMF, SMF, UPF, PCF, UDM, AUSF, NSSF, NEF, NRF, and AF shown in FIG. 1 may be understood as network elements configured to perform different functions. For example, it should be further understood that they may be combined into network slices as needed. These network elements may be independent devices, integrated into the same device to implement different functions, network elements within a hardware device, software functions executed on dedicated hardware, or virtualized functions instantiated on a platform (such as a cloud platform). The specific form of the network element is not limited in this application.

[0153] It should be further understood that the above names are defined merely to facilitate the distinction of different functions and do not constitute any limitation to this application. This application does not exclude the possibility of using other names in 6G networks and other future networks. For example, in a 6G network, some or all of the above network elements may still use the terms in 5G, or use other names.

[0154] The technical solution provided in this application may be applied to a relay scenario where a remote terminal is connected to a network via a relay terminal.

[0155] In one example, FIG. 2 is a diagram of a network architecture in a relay scenario. The network architecture shown in FIG. 2 may be based on, but not limited to, the 5G architecture shown in FIG. 1.

[0156] As shown in FIG. 2, the network architecture includes a remote terminal, a relay terminal, an access network device, a UPF, and a data network. The remote terminal may also be referred to as a remote UE, and is a terminal that obtains a relay service, such as a wristwatch, a band, or an augmented reality (AR) headset / virtual reality (VR) headset. The relay terminal may also be referred to as a relay UE, and is a terminal that provides a relay service, such as a smartphone or customer-premises equipment (CPE). The remote terminal may exchange data with the data network via the relay terminal, the access network device, and the UPF. The remote terminal may communicate with the relay terminal, for example, through a PC5 interface. The relay terminal may communicate with the UPF by using the PDU session of the relay terminal, and the relay terminal may communicate with the access network device through the Uu interface. The UPF may communicate with the data network, for example, through an N6 interface.

[0157] It should be noted that the embodiments of this application may be applied to the network architecture shown in FIG. 1 or the network architecture shown in FIG. 2, but are not limited thereto.

[0158] To facilitate the understanding of the technical solutions in this application, the layer-3 relay in this application is first described.

[0159] In the 5G system, indirect communication (i.e., a communication mode in which a remote terminal accesses the network via a relay terminal) supports a layer-3 relay (L3 relay) method. In the layer-3 relay, the relay terminal establishes a PDU session with the UPF and transfers the uplink data and downlink data of the remote terminal based on IP routing.

[0160] Figure 3 is a schematic flowchart of connection establishment of the Layer 3 relay.

[0161] In the Layer 3 relay scenario, the remote terminal is described as a remote UE, and the relay terminal is described as a proximity-based service (ProSe) UE-to-NW relay. For the sake of brevity, the description methods of the remote terminal and the relay terminal are still used hereinafter.

[0162] Step 1: The remote terminal and the relay terminal register with the network separately and obtain the authorization information and parameter information used for D2D communication.

[0163] For the remote terminal, the authorization information includes information indicating whether the terminal is authorized to function as a remote terminal and access the network via the relay terminal. For the relay terminal, the authorization information includes information indicating whether the terminal is authorized to function as a relay terminal and provide a relay service to the remote terminal.

[0164] The parameter information used for D2D communication includes QoS mapping configuration, relay service code (RSC), and PDU session parameters corresponding to each RSC. The RSC identifies a relay connection (e.g., a PC5 connection). For a relay terminal, the RSC may identify the connection service provided by the relay terminal for a remote terminal. For a remote terminal, the RSC may identify the connection service that the remote terminal is interested in or expects. The PDU session parameters corresponding to the RSC may include at least one of the following, namely, PDU session type, data network name (DNN), session and service continuity (SSC) mode, single network slice selection assistance information (S-NSSAI), or access type preference.

[0165] Step 2: The relay terminal establishes a PDU session.

[0166] After the PDU session is established, the SMF may allocate an IP address to the relay terminal, and the relay terminal may perform data transmission between the relay terminal and the UPF by using the PDU session. The PDU session may be a PDU session dedicated to the relay service.

[0167] It should be noted that Step 2 is an optional step.

[0168] Step 3: The remote terminal and the relay terminal execute a relay discovery procedure.

[0169] The remote terminal and the relay terminal may discover each other through a relay discovery procedure. There may be two types of relay discovery procedures, namely, model A and model B.

[0170] (1) Relay discovery procedure using model A

[0171] The relay terminal actively sends a discovery message (e.g., an announcement message), and the remote terminal listens for and receives the discovery message. The discovery message includes the RSC of the connection service that can be provided by the relay terminal.

[0172] In this way, the remote terminal may perform a comparison between the RSC of the expected connection service and the RSC in the discovery message, and select a relay terminal whose RSC matches the RSC of the expected connection service.

[0173] The RSC of the connection service that can be provided by the relay terminal may be configured by the PCF.

[0174] (2) Relay discovery procedure using model B

[0175] The remote terminal actively sends a discovery message (e.g., a solicitation message), and the relay terminal listens for and receives the discovery message. The discovery message includes the RSC of the connection service expected by the remote terminal. The relay terminal may perform a comparison between the RSC of the connection service it can provide and the RSC in the discovery message. If the RSC of the connection service that can be provided by the relay terminal matches the RSC in the discovery message, the relay terminal responds to the discovery message. In other words, the relay terminal may send a response message to the remote terminal.

[0176] In this way, the remote terminal may select a relay terminal from one or more relay terminals that send response messages.

[0177] The remote terminal may determine the RSC of the expected connection service based on the correspondence between the application and the RSC. The correspondence may be configured by the PCF. The RSC of the connection service that can be provided by the relay terminal may be configured by the PCF.

[0178] Step 4: The remote terminal establishes a PC5 connection to the relay terminal.

[0179] PC5 is an interface between terminals, and the PC5 connection is used for communication between terminals.

[0180] Optionally, the relay terminal determines whether to establish a new PDU session based on the correspondence between the RSC and the PDU session parameters, in other words, whether the PDU session established by the relay terminal (for example, the PDU session established in Step 2) meets the session requirements of the remote terminal. If the PDU session established by the relay terminal does not meet the session requirements of the remote terminal, the relay terminal establishes a new PDU session for the remote terminal. The new PDU session may be dedicated to the relay service, and the session parameters of the new PDU session may be determined by the relay terminal based on the correspondence between the RSC and the PDU session parameters.

[0181] Step 5: The relay terminal assigns an IP address used for PC5 communication to the remote terminal.

[0182] Step 6: The relay terminal reports the identifier and IP information of the remote terminal to the AMF and the SMF.

[0183] The IP information includes the address assigned by the relay terminal to the remote terminal for network-side communication. For example, when the IP address assigned by the SMF to the relay terminal is IPv4, the IP information is a specific port number (e.g., transmission control protocol (TCP) / user datagram protocol (UDP) port). This means that the relay terminal uses the IPv4 address and the specific port number to execute the transmission of the remote terminal's data. In another example, when the IP address assigned by the SMF to the relay terminal is an IPv6 prefix, the IP information is a longer IPv6 prefix. This means that the relay terminal uses the longer IPv6 prefix to execute the transmission of the remote terminal's data.

[0184] In the implementation method, the relay terminal may report the identifier and IP information of the remote terminal to the AMF and SMF via the PDU session modification process.

[0185] Thereafter, the relay terminal may transfer the uplink data and downlink data of the remote terminal based on the IP address.

[0186] For example, assume that the IP address used by the remote terminal on the PC5 connection is IP3, the IP address corresponding to the PDU session of the relay terminal is IP1, and the IP information assigned by the relay terminal to the remote terminal is IP1-1. In this way, the remote terminal sends data to the data network by using IP3, the data network sends data to the remote terminal by using IP1-1, and the relay terminal generates an association relationship between IP3 and IP1-1. In the uplink direction, after receiving data with the IP address IP3, the relay terminal changes the IP address from IP3 to IP1-1 and sends the data to the UPF by using the PDU session corresponding to IP1, and then sends the data to the data network. In the downlink direction, after receiving data with the IP address IP1-1 from the UPF, the relay terminal determines that the data belongs to the remote terminal, changes the IP address from IP1-1 to IP3, and sends the data to the remote terminal through the PC5 connection.

[0187] For a more detailed description of the layer 3 relay, refer to the prior art. Details will not be described again here.

[0188] In this application, the PC5 connection may also be referred to as a PC5 communication connection, a PC5 link, or a PC5 communication link, and the PC5 connection will be uniformly used hereinafter.

[0189] It should be noted that the embodiments of this application may be applied to the above layer 3 relay scenario, or may be applied to other relay scenarios, such as a layer 2 relay scenario. This is not limited. For the description of the layer 2 relay, refer to the prior art. Details will not be described again here.

[0190] Hereinafter, with reference to the accompanying drawings, the communication method provided in this application will be described in detail.

[0191] The technical solution in this application is applicable to the transmission of abnormal services in a relay scenario. The abnormal service may be understood as a service other than a normal service. For example, the abnormal service may be an emergency service, a multimedia priority service, or a mission critical service. This is not limited. Hereinafter, an example where the abnormal service is an emergency service will be used to explain the technical solution in this application. Furthermore, in this application, "service" may be replaced by "service". For example, the emergency service may alternatively be described as an emergency service.

[0192] FIG. 4 is a diagram of a communication method 400 according to this application. The method 400 may include at least a part of the following content.

[0193] Step 401: The relay terminal determines that the network accessed by the relay terminal supports an emergency service.

[0194] "Network" may include an access network and / or a core network. "The network supports an emergency service" may be understood as that the access network device and / or the core network element supports an emergency service. The access network device and / or the core network element here may be any access network device and / or any core network device, any core network element and / or any access network device related to the DN providing the emergency service, or the core network element and / or the access network device related to the DN providing the emergency service and configured to transmit the emergency service to the relay terminal. This is not limited in this application.

[0195] The network supporting emergency services may be understood as the network supporting the transmission of emergency services, the network supporting the configuration or control of emergency services, the network having the capabilities or resources for the transmission of emergency services, etc.

[0196] The emergency service may be a general service type or may be called an emergency service type. The emergency service type may include one or more emergency services. For example, the emergency service type includes an emergency voice service, an emergency video service, and an emergency short message service. In this case, the network accessed by the relay terminal supporting the emergency service may be understood as the network accessed by the relay terminal supporting any emergency service in the emergency service type.

[0197] Alternatively, the emergency service may be a specific emergency service, such as an emergency voice service, an emergency video service, or an emergency short message service. In this case, the network accessed by the relay terminal supporting the emergency service may be understood as the network accessed by the relay terminal supporting the specific emergency service. For example, the network accessed by the relay terminal supports the emergency voice service.

[0198] In a possible implementation manner, before the relay terminal determines that the network accessed by the relay terminal supports the emergency service, method 400 further includes the following. The relay terminal determines that the first message includes a relay service code corresponding to the emergency service.

[0199] In other words, when the relay service code included in the first message corresponds to an emergency service, the relay terminal may determine whether the network accessed by the relay terminal supports the emergency service. When the relay service code included in the first message does not correspond to an emergency service, the relay terminal may not need to determine whether the network accessed by the relay terminal supports the emergency service.

[0200] In this application, there are many ways for the relay terminal to determine whether the network accessed by the relay terminal supports the emergency service. This is not limited.

[0201] In a possible implementation manner, when at least one of the following cases is satisfied, the relay terminal determines that the network accessed by the relay terminal supports the emergency service. The relay terminal has received an emergency service support indicator from the AMF or the access network device, the relay terminal stores an emergency service support indicator, or the relay terminal has established an emergency PDU session.

[0202] In another possible implementation manner, when none of the following cases is satisfied, the relay terminal determines that the network accessed by the relay terminal does not support the emergency service. The relay terminal has received an emergency service support indicator from the AMF or the access network device, the relay terminal stores an emergency service support indicator, or the relay terminal has established an emergency PDU session.

[0203] The emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service.

[0204] The "emergency PDU session" here may be understood as a PDU session used for the transmission of emergency services, or may be understood as a PDU session corresponding to an emergency data network name (DNN).

[0205] Optionally, the relay terminal is a layer 3 relay terminal or a layer 2 relay terminal.

[0206] Step 402: The relay terminal sends a first message to the remote terminal.

[0207] Correspondingly, the remote terminal receives the first message from the relay terminal.

[0208] The first message is used for the remote terminal to discover the relay terminal.

[0209] In a possible implementation, the first message is a first discovery message, and the first discovery message includes an RSC corresponding to the emergency service. For example, when the remote terminal and the relay terminal use the relay discovery procedure using model A, the first message is the first discovery message. For the description of the relay discovery procedure using model A, refer to the related description in FIG. 3. Details will not be described again here.

[0210] In another possible implementation, the first message is a response message, and the response message is used to respond to a second discovery message from the remote terminal. The second discovery message includes a relay service code corresponding to the emergency service. For example, when the remote terminal and the relay terminal use the relay discovery procedure using model B, the first message is the response message. For the description of the relay discovery procedure using model B, refer to the related description in FIG. 3. Details will not be described again here.

[0211] The RSC for emergency service (RSC for emergency service) may alternatively be described as the RSC for emergency service, the RSC used for emergency service, etc.

[0212] Based on different meanings of emergency services, correspondingly, the RSC for emergency service may also have different meanings.

[0213] Specifically, when the emergency service is a service type, the RSC for emergency service is the RSC corresponding to the emergency service type. In this case, the services of the emergency service type correspond to the same RSC. For example, assume that the emergency service type includes emergency voice service, emergency video service, and emergency short message service. In this case, the RSCs corresponding to the emergency voice service, emergency video service, and emergency short message service are the same.

[0214] When the emergency service is a specific emergency service, the RSC for emergency service may alternatively be the RSC corresponding to the specific emergency service. In this case, the different services of the emergency service type may correspond to the same RSC or different RSCs. For example, assume that the emergency service type includes emergency voice service, emergency video service, and emergency short message service. In this case, the emergency voice service corresponds to RSC1, the emergency video service corresponds to RSC2, and the emergency short message service corresponds to RSC3, or the emergency voice service corresponds to RSC1, and the emergency video service and the emergency short message service correspond to RSC2. This is not limited.

[0215] Optionally, when the relay terminal is in the emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the relay terminal is in the emergency registration state. The emergency registration time information indicates at least one of the time that the relay terminal has been in the emergency registration state, the remaining time that the relay terminal will be in the emergency registration state, or the time that the relay terminal was in the emergency registration state. The time that the relay terminal has been in the emergency registration state may be understood as the total time that the relay terminal can maintain the emergency registration state.

[0216] For example, when the total time that the relay terminal can maintain the emergency registration state is 5s, the remaining time that the relay terminal is in the emergency registration state is 3s, and the time that the relay terminal was in the emergency registration state is 2s, the emergency registration time information may indicate at least one of 5s, 3s, or 2s.

[0217] In the registration process, the terminal includes the registration type in the registration request message, and the emergency registration is one of the registration types. Therefore, the fact that the relay terminal is in the emergency registration state may be understood as the relay terminal being in the emergency registration process.

[0218] Optionally, method 400 further includes the following. The relay terminal generates or determines the first message.

[0219] Step 403: The remote terminal selects a relay terminal based on the first message.

[0220] In a possible implementation, the remote terminal receives one or more first messages and selects a relay terminal from the relay terminals that send one or more first messages.

[0221] Optionally, one or more first messages received by the remote terminal include a first message from a first relay terminal, and the first message from the first relay terminal includes an emergency registration indicator and / or emergency registration time information. When selecting a relay terminal from relay terminals that transmit one or more first messages, the remote terminal considers that the first message from the first relay terminal includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the first relay terminal is in an emergency registration state. The emergency registration time information indicates at least one of the time when the first relay terminal is in an emergency registration state, the remaining time when the first relay terminal is in an emergency registration state, or the time when the first relay terminal was in an emergency registration state.

[0222] For example, the remote terminal preferentially selects a relay terminal in a non-emergency registration state.

[0223] In another example, when all relay terminals that transmit the first message are in an emergency registration state, the remote terminal preferentially selects a relay terminal with a longer remaining emergency registration time.

[0224] In this application, the first relay terminal may be one relay terminal or a plurality of relay terminals.

[0225] It should be noted that the order of step 401 and step 402 is not limited in this application.

[0226] In a possible implementation, step 401 is executed before step 402. Specifically, after determining that the network accessed by the relay terminal supports emergency services, the relay terminal transmits a first message to the remote terminal.

[0227] In one example, when the relay terminal determines that the network accessed by the relay terminal supports emergency services, the relay terminal transmits a first message to the remote terminal. For example, in the relay discovery procedure using Model A, when the relay terminal determines that the network accessed by the relay terminal supports emergency services, the relay terminal transmits a first discovery message to the remote terminal. Further, when the relay terminal determines that the network accessed by the relay terminal does not support emergency services, the relay terminal may not transmit the first discovery message to the remote terminal, or the relay terminal transmits the first discovery message to the remote terminal, but the first discovery message does not carry the RSC corresponding to the emergency service.

[0228] In another example, when the relay terminal determines that the network accessed by the relay terminal supports emergency services and determines that other conditions are met (for example, the RSC of the connection service that can be provided by the relay terminal matches the RSC in the discovery message received from the remote terminal), the relay terminal transmits a first message to the remote terminal. For example, in the relay discovery procedure using Model B, when the relay terminal determines that the network accessed by the relay terminal supports emergency services and the RSC of the connection service that can be provided by the relay terminal matches the RSC in the discovery message received from the remote terminal, the relay terminal transmits a response message to the second discovery message to the remote terminal.

[0229] In other words, when the network accessed by the relay terminal does not support emergency services, the relay terminal does not participate in the relay discovery procedure for emergency services, and only when the network accessed by the relay terminal supports emergency services, the relay terminal may participate in the relay discovery procedure for emergency services (for example, transmit the first discovery message to the remote terminal, or respond to the second discovery message transmitted by the remote terminal).

[0230] According to the above technical solution, it is ensured that the network accessed by the relay terminal participating in the relay discovery procedure of the emergency service supports the emergency service, and it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide a relay service for the emergency service. This facilitates the transmission of the emergency service in the relay scenario.

[0231] In some other embodiments of this application, the relay terminal may further determine whether the network authorizes the remote terminal to access the emergency service, so as to avoid the access of the unauthorized remote terminal to the emergency service. In this application, "access to the emergency service" may alternatively be replaced with "use the emergency service", "acquire the emergency service", etc.

[0232] In a possible implementation manner, in the procedure of establishing a connection to the remote terminal, the relay terminal determines whether the network authorizes the remote terminal to access the emergency service.

[0233] In this case, method 400 further includes the following. The remote terminal sends a third message to the relay terminal. Correspondingly, the relay terminal receives the third message from the remote terminal. The third message is used to request establishing a connection to the relay terminal, and the connection is used for the transmission of emergency services. After receiving the third message, the relay terminal sends the second message to the AMF. Correspondingly, the AMF receives the second message from the relay terminal. The second message is used to request authorizing the remote terminal to access emergency services. After receiving the second message, the AMF sends the authorization result to the relay terminal. Correspondingly, the relay terminal receives the authorization result from the AMF. If the authorization result indicates that the remote terminal has successfully been authorized to access emergency services, the relay terminal sends a fifth message to the remote terminal. Correspondingly, the remote terminal receives the fifth message from the relay terminal. The fifth message includes information indicating that the connection has been successfully established. Alternatively, if the authorization result indicates that the remote terminal has failed to be authorized to access emergency services, the relay terminal sends a sixth message to the remote terminal. Correspondingly, the remote terminal receives the sixth message from the relay terminal. The sixth message includes information indicating that the connection has not been established. Optionally, the sixth message further includes a cause value, and the cause value is an authorization failure.

[0234] Optionally, the connection between the remote terminal and the relay terminal is a direct communication connection. The third message is a direct communication request (DCR) message. The fifth message is a direct communication accept message. The sixth message is a direct communication reject message.

[0235] Optionally, the second message and the fourth message are authorization request messages, and the authorization result is conveyed in an authorization response message.

[0236] In other possible implementation manners, in a relay discovery procedure (for example, a relay discovery procedure using Model B), the relay terminal determines whether the network authorizes the remote terminal to access the emergency service. It should be noted that in this application, the order in which the relay terminal determines whether the network accessed by the relay terminal supports the emergency service and whether the network authorizes the remote terminal to access the emergency service is not limited.

[0237] In one example, method 400 further includes the following. The remote terminal sends a second discovery message to the relay terminal, and correspondingly, the relay terminal receives the second discovery message from the remote terminal, and the second discovery message includes an RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal sends a second message to the AMF, and correspondingly, the AMF receives the second message from the relay terminal, and the second message is used to request authorization for the remote terminal to access the emergency service. After receiving the second message, the AMF sends the authorization result to the relay terminal, and correspondingly, the relay terminal receives the authorization result from the AMF. Step 401 may specifically include the following. When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the relay terminal executes step 401.

[0238] Furthermore, when the authorization result indicates that the remote terminal has failed to obtain authorization to access the emergency service, the relay terminal may not execute step 401.

[0239] In other words, after receiving the second discovery message of the remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access the emergency service. When the network normally authorizes the remote terminal to access the emergency service, the relay terminal further determines whether the network accessed by the relay terminal supports the emergency service. Thereafter, the relay terminal transmits or does not transmit a response message to the second discovery message depending on whether the network accessed by the relay terminal supports the emergency service. Obviously, when determining whether to transmit a response message to the second discovery message, the relay terminal may further consider other factors, such as whether the RSC matches.

[0240] In another example, method 400 further includes the following. The remote terminal sends a second discovery message to the relay terminal, and correspondingly, the relay terminal receives the second discovery message from the remote terminal, and the second discovery message includes an RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal determines whether the network accessed by the relay terminal supports the emergency service. If the network accessed by the relay terminal supports the emergency service, the relay terminal sends the second message to the AMF, and correspondingly, the AMF receives the second message from the relay terminal, and the second message is used to request that the remote terminal be authorized to access the emergency service. After receiving the second message, the AMF sends the authorization result to the relay terminal, and correspondingly, the relay terminal receives the authorization result from the AMF. Step 402 may specifically include the following. When the authorization result indicates that the remote terminal has successfully been authorized to access the emergency service, the relay terminal sends a response message to the second discovery message to the remote terminal. Further, when the authorization result indicates that the remote terminal has failed to be authorized to access the emergency service, the relay terminal may not send a response message to the second discovery message to the remote terminal. Apparently, when determining whether to send a response message to the second discovery message, the relay terminal may further consider other factors, such as whether the RSCs match.

[0241] Further, if the network accessed by the relay terminal does not support the emergency service, the relay terminal may not send the second message to the AMF.

[0242] In other words, after receiving the second discovery message from the remote terminal, the relay terminal first determines whether the network accessed by the relay terminal supports emergency services. When the network accessed by the relay terminal supports emergency services, the relay terminal further determines whether the network authorizes the remote terminal to access the emergency services. Thereafter, the relay terminal sends a response message to the second discovery message or does not send it depending on whether the network authorizes the remote terminal to access the emergency services.

[0243] In yet another example, method 400 further includes the following. The remote terminal sends a second discovery message to the relay terminal. Correspondingly, the relay terminal receives the second discovery message from the remote terminal, and the second discovery message includes an RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal determines whether the network accessed by the relay terminal supports emergency services, and sends a second message to the AMF. The second message is used to request authorization for the remote terminal to access the emergency services. After receiving the second message, the AMF sends the authorization result to the relay terminal. Correspondingly, the relay terminal receives the authorization result from the AMF. Step 402 may specifically include the following. When the network accessed by the relay terminal supports emergency services and the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency services, the relay terminal sends a response message to the second discovery message to the remote terminal. Obviously, when determining whether to send a response message to the second discovery message, the relay terminal may further consider other factors, such as whether the RSCs match.

[0244] Furthermore, when the network accessed by the relay terminal does not support emergency services and / or the authorization result indicates that the remote terminal has failed to obtain authorization to access the emergency services, the relay terminal may not send a response message to the second discovery message to the remote terminal.

[0245] In other words, after receiving the second discovery message of the remote terminal, the relay terminal determines whether the network accessed by the relay terminal supports emergency services, and determines whether the network authorizes the remote terminal to access emergency services. Then, the relay terminal comprehensively considers factors such as whether the network accessed by the relay terminal supports emergency services and whether the network authorizes the remote terminal to access emergency services, and sends or does not send a response message to the second discovery message.

[0246] Optionally, method 400 further includes the following. The AMF obtains the authorization result before sending the authorization result to the relay terminal, and the authorization result indicates whether the remote terminal has successfully obtained authorization to access emergency services or has failed to obtain authorization to access emergency services.

[0247] In a possible implementation, the AMF obtains the authorization result from the authorization network element. Specifically, the AMF sends a fourth message to the authorization network element, and correspondingly, the authorization network element receives the fourth message from the AMF, and the fourth message is used to request authorization for the remote terminal to access emergency services. The authorization network element sends the authorization result to the AMF, and correspondingly, the AMF receives the authorization result from the authorization network element.

[0248] The specific type of the authorization network element is not limited in this application. For example, the authorization network element may be a UDM, a PCF, or an AUSF.

[0249] Optionally, method 400 further includes the following. The remote terminal transmits a seventh message to the relay terminal, and correspondingly, the relay terminal receives the seventh message from the remote terminal. The seventh message is used to request establishing a connection to the relay terminal, and the connection is used for the transmission of emergency services. After receiving the seventh message, if the relay terminal does not have an emergency PDU session, the relay terminal requests to establish an emergency PDU session, or if the relay terminal has established an emergency PDU session, the relay terminal may not need to request to establish an emergency PDU session.

[0250] Optionally, the connection between the remote terminal and the relay terminal is a direct communication connection, and the seventh message is a direct communication request message.

[0251] It should be noted that the seventh message and the third message may be the same message or different messages. This is not limited.

[0252] In some other embodiments of this application, method 400 may further include the following. The PCF obtains a relay service code corresponding to an emergency service. The PCF transmits first configuration information to the relay terminal, and correspondingly, the relay terminal receives the first configuration information from the PCF, where the first configuration information includes a relay service code corresponding to the emergency service, and / or the PCF transmits second configuration information to the remote terminal, and correspondingly, the remote terminal receives the second configuration information from the PCF, where the second configuration information includes a relay service code corresponding to the emergency service. In other words, the PCF configures a relay service code corresponding to the emergency service for the relay terminal and / or the remote terminal. It should be noted that the steps here only indicate that the PCF configures a relay service code corresponding to the emergency service for the relay terminal and the remote terminal. The fact that the PCF configures a relay service code corresponding to the emergency service for the relay terminal and the fact that the PCF configures a relay service code corresponding to the emergency service for the relay terminal and the remote terminal are independent processes. In the configuration process, the PCF does not consider whether the connection will be established between the relay terminal and the remote terminal later.

[0253] Optionally, the PCF obtaining a relay service code corresponding to an emergency service includes the following. The PCF obtains a relay service code corresponding to the emergency service locally or from the AF. The local relay service code corresponding to the emergency service in the PCF may be pre-configured or pre-defined.

[0254] When the PCF obtains the RSC corresponding to the emergency service from the AF, it can ensure that the RSCs of different public land mobile networks (PLMNs) are consistent. Therefore, the inter-PLMN relay service used for the emergency service can be better supported (specifically, the relay terminal and the remote terminal access different PLMNs, and the relay terminal provides the relay service of the emergency service to the remote terminal).

[0255] Optionally, the first configuration information further includes the priority of the relay service code corresponding to the emergency service. In this case, method 400 further includes the following. The relay terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service. That the connection is used for the transmission of the emergency service may be understood as that the RSC included in the context of the connection corresponds to the emergency service. The connection may be understood as a PC5 connection.

[0256] For example, the PCF configures, for the relay terminal, a plurality of RSCs including the RSC corresponding to the emergency service and the priority of each of the plurality of RSCs by using the first configuration information. The relay terminal establishes a plurality of connections to the remote terminal, and the plurality of connections have a one-to-one correspondence with the plurality of RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), and connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the relay terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the relay terminal are limited, the relay terminal may release the connection with the lower priority of the RSCs from the plurality of established connections.

[0257] Optionally, the second configuration information further includes the priority of the relay service code corresponding to the emergency service. In this case, method 400 further includes the following. The remote terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service. That the connection is used for the transmission of the emergency service may be understood as that the RSC included in the context of the connection corresponds to the emergency service. The connection may be understood as a PC5 connection.

[0258] For example, the PCF configures, for a remote terminal, a plurality of RSCs including an RSC for emergency services and priorities of the respective plurality of RSCs by using second configuration information. The remote terminal establishes a plurality of connections to a relay terminal, and the plurality of connections have a one-to-one correspondence with the plurality of RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), and connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the remote terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the remote terminal are limited, the remote terminal may release the connection with a lower priority of the RSC from the plurality of established connections.

[0259] In some other embodiments of this application, method 400 further includes the following. The relay terminal transmits first information to the AMF, and correspondingly, the AMF receives the first information from the relay terminal, and the first information indicates that the relay service of the relay terminal is used for an emergency service (relay service for emergency service), or the first information indicates that the relay terminal provides an emergency service to the remote terminal. In other words, the relay terminal reports to the AMF that the relay terminal is in a state of providing a relay service for an emergency service or the relay terminal is in a state of providing an emergency service to the remote terminal, so that the AMF does not restrict the relay terminal regarding access management or mobility management. For example, the relay terminal may provide a relay service for an emergency service within a non-allowed area. Similarly, the emergency service here may be a general service type or a specific emergency service.

[0260] Optionally, after the AMF receives the first information, the AMF stores the first information in the context of the relay terminal.

[0261] Optionally, the first information may be carried in a service request message, a PDU session establishment message, or a registration message.

[0262] Optionally, when the PDU session establishment message carries the first information, the first information indicates that the PDU session is used for the transmission of emergency services. In this case, the AMF selects an SMF that can provide emergency services based on the first information, or alternatively, the AMF sends the first information to the SMF. When the AMF sends the first information to the SMF, the SMF knows that the PDU session is used for the transmission of emergency services based on the first information, and then selects a UPF that can provide emergency services.

[0263] In some other embodiments of this application, the method 400 further includes the following. The relay terminal sends second information to the AMF, and correspondingly, the AMF receives the second information from the relay terminal. The second information indicates that the relay terminal's provision of emergency services to the remote terminal is cancelled, or the second information indicates that the relay terminal does not provide emergency services to the remote terminal. In other words, the relay terminal reports to the AMF that the relay terminal is not in a state of providing relay services for emergency services or that the relay terminal is not in a state of providing emergency services to the remote terminal, so that the AMF restricts the relay terminal regarding access management or mobility management.

[0264] Optionally, after the AMF receives the second information, the AMF deletes the first information from the context of the relay terminal.

[0265] Optionally, after the relay terminal releases the connection used for the transmission of emergency services, the relay terminal sends the second information to the AMF. Alternatively, if the relay terminal no longer has the connection used for the transmission of emergency services, the relay terminal sends the second information to the AMF.

[0266] It should be noted that in method 400, "the network accessed by the relay terminal supports emergency services" may alternatively be replaced by "the network supports emergency services".

[0267] In method 400, the relay terminal determines whether the network accessed by the relay terminal supports emergency services. In some other embodiments of this application, the PCF may alternatively determine whether the network accessed by the relay terminal supports emergency services, and when the network accessed by the relay terminal supports emergency services, provide the relay terminal with the RSC corresponding to the emergency service. A detailed description will be provided below with reference to FIG. 5.

[0268] FIG. 5 is a diagram of a communication method 500 according to this application. The method 500 may include at least a part of the following content.

[0269] Step 501: The PCF determines that the network accessed by the relay terminal supports emergency services.

[0270] For the description of "the network supports emergency services" and the description of "emergency services", refer to step 401. Details will not be described again here.

[0271] In this application, there are many ways for the PCF to determine whether the network accessed by the relay terminal supports emergency services. This is not limited.

[0272] In a possible implementation, when at least one of the following cases is satisfied, the PCF determines that the network accessed by the relay terminal supports emergency services. The PCF has received an emergency service support indicator from the AMF, or the PCF has stored or pre-configured the emergency service support indicator. In another possible implementation, when none of the following cases is satisfied, the PCF determines that the network accessed by the relay terminal does not support emergency services. The PCF has received an emergency service support indicator from the AMF, or the PCF has stored or pre-configured the emergency service support indicator.

[0273] The emergency service support indicator indicates that the network accessed by the relay terminal supports emergency services.

[0274] Optionally, the emergency service support indicator stored or pre-configured in the PCF is network capability information.

[0275] Optionally, the network capability information is from an operation administration and maintenance (OAM) network element.

[0276] Step 502: When the network accessed by the relay terminal supports emergency services, the PCF sends the first configuration information to the relay terminal.

[0277] Correspondingly, the relay terminal receives the first configuration information from the PCF.

[0278] The first configuration information includes the RSC corresponding to the emergency service.

[0279] For the description of the "RSC corresponding to the emergency service", refer to Step 402. Details are not described again here.

[0280] Optionally, method 500 further includes the following. The PCF obtains a relay service code corresponding to an emergency service. In a possible implementation, the PCF obtaining a relay service code corresponding to an emergency service includes the following. The PCF obtains the relay service code corresponding to the emergency service locally or from the AF. The local relay service code corresponding to the emergency service in the PCF may be pre-configured or pre-defined.

[0281] When the PCF obtains the RSC corresponding to the emergency service from the AF, it can be ensured that the RSCs of different PLMNs are consistent. Therefore, the inter-PLMN relay service used for emergency services can be better supported (specifically, the relay terminal and the remote terminal access different PLMNs, and the relay terminal provides the relay service of the emergency service to the remote terminal).

[0282] In other words, the PCF configures the relay service code corresponding to the emergency service for the relay terminal only when the network accessed by the relay terminal supports the emergency service, so that the relay terminal participates in the relay discovery procedure of the emergency service.

[0283] Step 503: The relay terminal sends a first message to the remote terminal.

[0284] Correspondingly, the remote terminal receives the first message from the relay terminal.

[0285] The first message is used for the remote terminal to discover the relay terminal.

[0286] In a possible implementation manner, the first message is the first discovery message, and the first discovery message includes an RSC corresponding to an emergency service. For example, when a remote terminal and a relay terminal use a relay discovery procedure using model A, the first message is the first discovery message. For the description of the relay discovery procedure using model A, refer to the relevant description in FIG. 3. Details will not be described again here.

[0287] In another possible implementation manner, the first message is a response message, and the response message is used to respond to a second discovery message from a remote terminal. The second discovery message includes a relay service code corresponding to an emergency service. For example, when a remote terminal and a relay terminal use a relay discovery procedure using model B, the first message is a response message. For the description of the relay discovery procedure using model B, refer to the relevant description in FIG. 3. Details will not be described again here.

[0288] Optionally, when the relay terminal is in an emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the relay terminal is in an emergency registration state. The emergency registration time information indicates at least one of the time when the relay terminal is in an emergency registration state, the remaining time when the relay terminal is in an emergency registration state, or the time when the relay terminal was in an emergency registration state. The time when the relay terminal is in an emergency registration state may be understood as the total time that the relay terminal can maintain the emergency registration state.

[0289] For example, when the total time that the relay terminal can maintain the emergency registration state is 5 s, the remaining time when the relay terminal is in an emergency registration state is 3 s, and the time when the relay terminal was in an emergency registration state is 2 s, the emergency registration time information may indicate at least one of 5 s, 3 s, or 2 s.

[0290] In the registration process, the terminal includes the registration type in the registration request message, and emergency registration is one of the registration types. Therefore, the fact that the relay terminal is in the emergency registration state may be understood as the relay terminal being in the emergency registration process.

[0291] Optionally, method 500 further includes the following. The relay terminal generates or determines a first message.

[0292] Step 504: The remote terminal selects a relay terminal based on the first message.

[0293] The implementation manner of step 504 is the same as that of step 403. Reference may be made to the description of step 403. Details will not be described again here.

[0294] According to the above technical solution, it is ensured that the network accessed by the relay terminal participating in the relay discovery procedure of the emergency service supports the emergency service, and it can be ensured that the relay terminal selected by the remote terminal expecting to access the emergency service can provide a relay service for the emergency service. This facilitates the transmission of emergency services in the relay scenario.

[0295] In some other embodiments of this application, the relay terminal may further determine whether the network authorizes the remote terminal to access the emergency service, so as to avoid the access of unauthorized remote terminals to the emergency service.

[0296] In a possible implementation manner, in the procedure of establishing a connection to the remote terminal, the relay terminal determines whether the network authorizes the remote terminal to access the emergency service.

[0297] In this case, method 500 further includes the following. The remote terminal sends a third message to the relay terminal, and correspondingly, the relay terminal receives the third message from the remote terminal. The third message is used to request the establishment of a connection to the relay terminal, and the connection is used for the transmission of emergency services. After receiving the third message, the relay terminal sends a second message to the AMF, and correspondingly, the AMF receives the second message from the relay terminal. The second message is used to request the authorization for the remote terminal to access emergency services. After receiving the second message, the AMF sends the authorization result to the relay terminal, and correspondingly, the relay terminal receives the authorization result from the AMF. If the authorization result indicates that the remote terminal has successfully obtained authorization to access emergency services, the relay terminal sends a fifth message to the remote terminal, and correspondingly, the remote terminal receives the fifth message from the relay terminal. The fifth message includes information indicating that the connection has been successfully established. Alternatively, if the authorization result indicates that the remote terminal has failed to obtain authorization to access emergency services, the relay terminal sends a sixth message to the remote terminal, and correspondingly, the remote terminal receives the sixth message from the relay terminal. The sixth message includes information indicating that the connection has not been established. Optionally, the sixth message further includes a cause value, and the cause value is an authorization failure.

[0298] Optionally, the connection between the remote terminal and the relay terminal is a direct communication connection, the third message is a direct communication request message, the fifth message is a direct communication acceptance message, and the sixth message is a direct communication rejection message.

[0299] Optionally, the second message and the fourth message are authorization request messages, and the authorization result is carried in an authorization response message.

[0300] In another possible implementation, in the relay discovery procedure (for example, the relay discovery procedure using Model B), the relay terminal determines whether the network authorizes the remote terminal to access the emergency service.

[0301] In this case, method 500 further includes the following. The remote terminal sends a second discovery message to the relay terminal. Correspondingly, the relay terminal receives the second discovery message from the remote terminal, and the second discovery message includes the RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal sends the second message to the AMF. Correspondingly, the AMF receives the second message from the relay terminal, and the second message is used to request that the remote terminal be authorized to access the emergency service. After receiving the second message, the AMF sends the authorization result to the relay terminal. Correspondingly, the relay terminal receives the authorization result from the AMF. Step 503 may specifically include the following. When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the relay terminal sends a response message to the second discovery message to the remote terminal. Obviously, when determining whether to send the response message to the second discovery message, the relay terminal may further consider other factors, such as whether the RSCs match.

[0302] Furthermore, when the authorization result indicates that the remote terminal has failed to obtain authorization to access the emergency service, the relay terminal may not send a response message to the second discovery message to the remote terminal.

[0303] Optionally, method 500 further includes the following. The AMF obtains the authorization result before the AMF sends the authorization result to the relay terminal, and the authorization result indicates whether the remote terminal has successfully obtained authorization to access the emergency service or has failed to obtain authorization to access the emergency service.

[0304] In a possible implementation manner, the AMF obtains an authorization result from an authorization network element. Specifically, the AMF sends a fourth message to the authorization network element. Correspondingly, the authorization network element receives the fourth message from the AMF, and the fourth message is used to request authorization for the remote terminal to access the emergency service. The authorization network element sends the authorization result to the AMF, and correspondingly, the AMF receives the authorization result from the authorization network element.

[0305] The specific type of the authorization network element is not limited in this application. For example, the authorization network element may be a UDM, a PCF, or an AUSF.

[0306] Optionally, method 500 further includes the following. The remote terminal sends a seventh message to the relay terminal. Correspondingly, the relay terminal receives the seventh message from the remote terminal, and the seventh message is used to request establishing a connection to the relay terminal, and the connection is used for the transmission of the emergency service. After receiving the seventh message, if the relay terminal does not have an emergency PDU session, the relay terminal requests to establish an emergency PDU session, or if the relay terminal has established an emergency PDU session, the relay terminal may not need to request to establish an emergency PDU session.

[0307] Optionally, the connection between the remote terminal and the relay terminal is a direct communication connection, and the seventh message is a direct communication request message.

[0308] It should be noted that the seventh message and the third message may be the same message or different messages. This is not limited.

[0309] In some other embodiments of this application, the first configuration information further includes the priority of the relay service code corresponding to the emergency service. In this case, method 500 further includes the following. The relay terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service. That the connection is used for the transmission of the emergency service may be understood as that the RSC included in the context of the connection corresponds to the emergency service. The connection may be understood as a PC5 connection.

[0310] For example, the PCF configures, for the relay terminal, a plurality of RSCs including the RSC corresponding to the emergency service and the priority of each of the plurality of RSCs by using the first configuration information. The relay terminal establishes a plurality of connections to the remote terminal, and the plurality of connections have a one-to-one correspondence with the plurality of RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), and connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the relay terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the relay terminal are limited, the relay terminal may release the connection with a lower priority of the RSC from the plurality of established connections.

[0311] In some other embodiments of this application, method 500 further includes the following. The PCF transmits the second configuration information to the remote terminal, and correspondingly, the remote terminal receives the second configuration information from the PCF, and the second configuration information includes the relay service code corresponding to the emergency service.

[0312] Optionally, the second configuration information further includes the priority of the relay service code corresponding to the emergency service. In this case, method 500 further includes the following. The remote terminal maintains or releases the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service. That the connection is used for the transmission of the emergency service may be understood as that the RSC included in the context of the connection corresponds to the emergency service. The connection may be understood as a PC5 connection.

[0313] For example, the PCF configures, for the remote terminal, a plurality of RSCs including the RSC corresponding to the emergency service and the priority of each of the plurality of RSCs by using the second configuration information. The remote terminal establishes a plurality of connections to the relay terminal, and the plurality of connections have a one-to-one correspondence with the plurality of RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), and connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the remote terminal releases a part of the established connections, for example, when the transmission resources or capabilities of the remote terminal are limited, the remote terminal may release the connection with a lower priority of the RSC from the plurality of established connections.

[0314] In some other embodiments of this application, method 500 further includes the following. The relay terminal sends the first information to the AMF, and correspondingly, the AMF receives the first information from the relay terminal. The first information indicates that the relay service of the relay terminal is used for emergency services, or the first information indicates that the relay terminal provides emergency services to the remote terminal. In other words, the relay terminal reports to the AMF that the relay terminal is in a state of providing a relay service for emergency services or a state of providing emergency services to the remote terminal, so that the AMF does not restrict the relay terminal regarding access management or mobility management. For example, the relay terminal may provide a relay service for emergency services within a non-allowed area. The emergency service here may be a general service type or a specific emergency service.

[0315] Optionally, after the AMF receives the first information, the AMF stores the first information in the context of the relay terminal.

[0316] Optionally, the first information may be carried in a service request message, a PDU session establishment message, or a registration message.

[0317] Optionally, when the PDU session establishment message carries the first information, the first information indicates that the PDU session is used for the transmission of emergency services. In this case, the AMF selects an SMF that can provide emergency services based on the first information, or the AMF sends the first information to the SMF. When the AMF sends the first information to the SMF, the SMF knows that the PDU session is used for the transmission of emergency services based on the first information, and then selects a UPF that can provide emergency services.

[0318] In some other embodiments of this application, method 500 further includes the following. The relay terminal transmits second information to the AMF. Correspondingly, the AMF receives the second information from the relay terminal, and the second information indicates that the relay terminal is cancelled from providing emergency services to the remote terminal, or the second information indicates that the relay terminal does not provide emergency services to the remote terminal. In other words, the relay terminal reports to the AMF that the relay terminal is not in a state of providing a relay service for emergency services or that the relay terminal is in a state of not providing emergency services to the remote terminal, and as a result, the AMF restricts the relay terminal regarding access management or mobility management.

[0319] Optionally, after the AMF receives the second information, the AMF deletes the first information from the context of the relay terminal.

[0320] Optionally, after the relay terminal releases the connection used for the transmission of emergency services, the relay terminal transmits the second information to the AMF. Alternatively, if the relay terminal no longer has the connection used for the transmission of emergency services, the relay terminal transmits the second information to the AMF.

[0321] It should be noted that "the network accessed by the relay terminal supports emergency services" in method 500 may alternatively be replaced with "the network supports emergency services".

[0322] Hereinafter, with reference to specific examples, the technical solutions in this application will be described.

[0323] Example 1

[0324] In Example 1, the relay terminal determines to participate in the relay discovery procedure for emergency services based on the fact that the network accessed by the relay terminal supports emergency services.

[0325] FIG. 6 is a diagram of a communication method 600 according to this application.

[0326] Step 601: The AF provides emergency service parameters to the PCF.

[0327] The emergency service parameters include an RSC corresponding to the emergency service.

[0328] In a possible implementation, the AF provides the emergency service parameters to the PCF via the NEF.

[0329] The AF provides the emergency service parameters to the PCF to ensure the consistency of the RSCs of different PLMNs. Therefore, the PLMN inter-relay service used for emergency services can be better supported.

[0330] It should be noted that step 601 is an optional step, and the PCF may alternatively obtain the RSC corresponding to the emergency service in other ways. For example, the RSC corresponding to the emergency service in the PCF may be predefined or preconfigured.

[0331] Step 602: The PCF provides the RSC corresponding to the emergency service to the remote terminal.

[0332] Optionally, the PCF further provides the priorities of different RSCs to the remote terminal, so that when resources are limited, the remote terminal preferentially releases the PC5 connection corresponding to the RSC with a lower priority.

[0333] The PC5 connection corresponding to the RSC may alternatively be understood as the PC5 connection identified by the RSC.

[0334] The "different RSCs" here are the RSCs provided by the PCF to the remote terminal, and may include the RSCs corresponding to normal services and / or the RSCs corresponding to emergency services.

[0335] In a possible implementation manner, as shown in FIG. 6, when providing a UE policy to a remote terminal, the PCF provides the RSC corresponding to the emergency service to the remote terminal, and the RSC corresponding to the emergency service is carried in a UE policy container.

[0336] Step 603: The PCF provides the RSC corresponding to the emergency service to the relay terminal.

[0337] Optionally, the PCF further provides the priorities of different RSCs to the relay terminal, so that when resources are limited, the relay terminal preferentially releases the PC5 connection corresponding to the RSC with a lower priority.

[0338] The "different RSCs" here are the RSCs provided by the PCF to the relay terminal, and may include the RSCs corresponding to normal services and / or the RSCs corresponding to emergency services.

[0339] In a possible implementation manner, as shown in FIG. 6, when providing a UE policy to a relay terminal, the PCF provides the RSC corresponding to the emergency service to the relay terminal, and the RSC corresponding to the emergency service is carried in a UE policy container.

[0340] Step 604: The network notifies the relay terminal that the network supports the emergency service.

[0341] In a possible implementation manner, the AMF sends an emergency service support indicator to the relay terminal. The emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service. In one example, the AMF sends the emergency service support indicator to the relay terminal during the registration process of the relay terminal. For example, the AMF includes the emergency service support indicator in a registration accept message.

[0342] In a possible implementation manner, the RAN device sends an emergency service support indicator to the relay terminal. The emergency service support indicator indicates that the network accessed by the relay terminal supports emergency services. In one example, the access network device sends the emergency service support indicator to the relay terminal during the network access process of the relay terminal. For example, the access network device includes the emergency service support indicator in an RRC configuration message (radio resource control configuration message). In other examples, the access network device sends the emergency service support indicator in a broadcast message, and the relay terminal receives the emergency service support indicator included in the broadcast message.

[0343] In this way, when the relay terminal receives an emergency service support indication, this means that the relay terminal can establish an emergency PDU session to obtain emergency services. The "emergency PDU session" here may be understood as a PDU session used for the transmission of emergency services, or may be understood as a PDU session corresponding to an emergency DNN.

[0344] It should be noted that step 603 and step 604 may be two independent steps, or may be executed together. For example, when the PCF provides the relay terminal with an RSC corresponding to an emergency service via the AMF during the registration process of the relay terminal, the AMF may provide the relay terminal with both the RSC corresponding to the emergency service and the emergency service support indicator.

[0345] Next, the remote terminal and the relay terminal may execute a relay discovery procedure. In Method 600, there may also be two methods of the relay discovery procedure, namely, Model A and Model B. When the relay discovery procedure using Model A is used, the following steps 605 and 606 are executed. When the relay discovery procedure using Model B is used, the following steps 607-609 are executed.

[0346] Step 605: The relay terminal determines that the network accessed by the relay terminal supports emergency services.

[0347] In a possible implementation, when an emergency service support indicator is received, when the emergency service support indicator is locally stored, or when an emergency PDU session is established, the relay terminal determines that the network accessed by the relay terminal supports emergency services.

[0348] Step 606: The relay terminal actively sends a discovery message (e.g., an announcement message).

[0349] Correspondingly, the remote terminal listens for and receives the discovery message.

[0350] The discovery message carries an RSC corresponding to the emergency service. The discovery message may correspond to the above first discovery message.

[0351] Optionally, when the relay terminal is in an emergency registration state, the discovery message further carries an emergency registration indicator and / or emergency registration time information for the remote terminal to perform relay selection. Obviously, when the relay terminal is in a non-emergency registration state, the discovery message does not carry the emergency registration indicator and / or emergency registration time information.

[0352] The emergency registration indicator indicates that the relay terminal is in the emergency registration state. In the registration process, the terminal includes the registration type in the registration request message, and emergency registration is one of the registration types. Therefore, the fact that the relay terminal is in the emergency registration state may be understood as the relay terminal being in the emergency registration process.

[0353] The emergency registration time information indicates at least one of the time when the relay terminal is in the emergency registration state, the remaining time (left time) when the relay terminal is in the emergency registration state, or the time when the relay terminal was in the emergency registration state. When the relay terminal performs emergency registration, the AMF assigns a periodic registration update timer to the relay terminal. The periodic registration update timer is the maximum value of the remaining time. After the periodic registration update timer expires, the relay terminal enters the deregistered state.

[0354] Step 607: When the remote terminal obtains an emergency service, the remote terminal actively sends a discovery message (e.g., a solicitation message).

[0355] Correspondingly, the relay terminal listens for and receives the discovery message.

[0356] The discovery message carries the RSC corresponding to the emergency service. The discovery message may correspond to the second discovery message described above.

[0357] Step 608: The relay terminal determines that the accessed network supports the emergency service.

[0358] In a possible implementation, when an emergency service support indicator is received, when the emergency service support indicator is locally stored, or when an emergency PDU session is established, the relay terminal determines that the network accessed by the relay terminal supports the emergency service.

[0359] It should be noted that the order of step 607 and step 608 is not limited in this application.

[0360] Step 609: When the network accessed by the relay terminal supports emergency services and the RSC of the relay terminal matches the RSC in the discovery message, the relay terminal sends a response message to the remote terminal.

[0361] Correspondingly, the remote terminal receives a response message from the relay terminal.

[0362] The response message here may correspond to the above response message.

[0363] Optionally, when the relay terminal is in an emergency registration state, the response message further carries an emergency registration indicator and / or emergency registration time information for the remote terminal to perform relay selection. Obviously, when the relay terminal is in a non-emergency registration state, the response message does not carry the emergency registration indicator and / or emergency registration time information. For the description of the emergency registration indicator and emergency registration time information, refer to step 606. Details will not be described again here.

[0364] Step 610: The remote terminal performs relay selection.

[0365] Specifically, the remote terminal may perform a comparison between the expected RSC and the RSC in the discovery message, and select a relay terminal whose RSC matches the expected RSC from one or more relay terminals that send the discovery message, or the remote terminal may select a relay terminal from one or more relay terminals that send the response message.

[0366] Optionally, the remote terminal further selects a relay terminal based on an emergency registration indicator and / or emergency registration time information carried in a discovery message or a response message. For example, the remote terminal preferentially selects a relay terminal in a non-emergency registration state. In another example, if all relay terminals transmitting discovery messages or response messages are in an emergency registration state, the remote terminal preferentially selects a relay terminal with a longer remaining time in the emergency registration state.

[0367] In Example 1, when the network accessed by the relay terminal supports an emergency service, the relay terminal participating in the relay discovery procedure for the emergency service includes transmitting an RSC corresponding to the emergency service in a discovery message or responding to a discovery message carrying an RSC corresponding to the emergency service. This helps to avoid the case where the relay terminal discovered by the remote terminal does not support the emergency service.

[0368] Example 2

[0369] In Example 2, based on the fact that the network accessed by the relay terminal supports an emergency service, the PCF determines to provide the relay terminal with an RSC corresponding to the emergency service, so that the relay terminal participates in the relay discovery procedure for supporting the emergency service.

[0370] FIG. 7 is a diagram of a communication method 700 according to this application.

[0371] Step 701: The AF provides emergency service parameters to the PCF.

[0372] The emergency service parameters include an RSC corresponding to the emergency service.

[0373] Step 702: The PCF provides the RSC corresponding to the emergency service to the remote terminal.

[0374] The implementation methods of steps 701 and 702 are the same as those of steps 601 and 602. Reference may be made to the descriptions of steps 601 and 602. Details will not be elaborated here again.

[0375] Step 703: The relay terminal registers with the network.

[0376] Specifically, the relay terminal sends a registration request message to the AMF. Correspondingly, the AMF receives the registration request message from the relay terminal.

[0377] Step 704: After receiving the registration request message, the AMF obtains the access information of the relay terminal from the UDM.

[0378] The access information includes information indicating whether the relay terminal is authorized to function as a relay terminal.

[0379] Step 705: If the relay terminal is authorized to function as a relay terminal, the AMF sends an emergency service support indicator to the PCF.

[0380] The emergency service support indicator indicates that the network accessed by the relay terminal supports emergency services.

[0381] In a possible implementation method, the AMF sends the emergency service support indicator to the PCF in an access management policy association (AM policy association) process.

[0382] It should be noted that step 705 is an optional step.

[0383] Step 706: The PCF determines that the network accessed by the relay terminal supports emergency services.

[0384] In a possible implementation manner, based on the emergency service support indicator in step 705, the PCF determines that the network accessed by the relay terminal supports emergency services.

[0385] In another possible implementation manner, based on the locally pre-configured network capability information, the PCF determines that the network accessed by the relay terminal supports emergency services, and the network capability information indicates that the network accessed by the relay terminal supports emergency services.

[0386] Step 707: If the network accessed by the relay terminal supports emergency services, the PCF provides the relay terminal with the RSC corresponding to the emergency service.

[0387] Optionally, the PCF further provides the relay terminal with the priorities of different RSCs, so that when resources are limited, the relay terminal preferentially releases the PC5 connection corresponding to the RSC with a lower priority.

[0388] The "different RSCs" here are the RSCs provided by the PCF to the relay terminal, and may include the RSCs corresponding to normal services and / or the RSCs corresponding to emergency services.

[0389] In a possible implementation manner, as shown in FIG. 7, when providing the UE policy to the relay terminal, the PCF provides the relay terminal with the RSC corresponding to the emergency service, and the RSC corresponding to the emergency service is carried in the UE policy container.

[0390] Next, the remote terminal and the relay terminal may execute a relay discovery procedure. In method 700, there may also be two methods for the relay discovery procedure, namely, model A and model B. When the relay discovery procedure using model A is used, the following step 708 is executed. When the relay discovery procedure using model B is used, the following steps 709 and 710 are executed.

[0391] Step 708: The relay terminal actively sends a discovery message (e.g., an announcement message).

[0392] Correspondingly, the remote terminal listens for and receives the discovery message.

[0393] The discovery message carries the RSC corresponding to the emergency service. The discovery message may correspond to the above-mentioned first discovery message.

[0394] Optionally, when the relay terminal is in the emergency registration state, the discovery message further carries an emergency registration indicator and / or emergency registration time information for the remote terminal to perform relay selection. Obviously, when the relay terminal is in the non-emergency registration state, the discovery message does not carry the emergency registration indicator and / or emergency registration time information.

[0395] The emergency registration indicator indicates that the relay terminal is in the emergency registration state.

[0396] The emergency registration time information indicates at least one of the time when the relay terminal is in the emergency registration state, the remaining time when the relay terminal is in the emergency registration state, or the time when the relay terminal was in the emergency registration state. When the relay terminal performs emergency registration, the AMF assigns a periodic registration update timer to the relay terminal. The periodic registration update timer is the maximum value of the remaining time. After the periodic registration update timer expires, the relay terminal enters the deregistration state.

[0397] Step 709: When the remote terminal obtains the emergency service, the remote terminal actively sends a discovery message (e.g., a solicitation message).

[0398] Correspondingly, the relay terminal listens for and receives the discovery message.

[0399] The discovery message conveys the RSC for the emergency service. The discovery message may correspond to the second discovery message described above.

[0400] Step 710: If the RSC of the relay terminal matches the RSC in the discovery message, the relay terminal sends a response message to the remote terminal.

[0401] Correspondingly, the remote terminal receives the response message from the relay terminal.

[0402] Optionally, if the relay terminal is in the emergency registration state, the response message further conveys an emergency registration indicator and / or emergency registration time information for the remote terminal to perform the relay selection. Obviously, if the relay terminal is in the non-emergency registration state, the response message does not convey the emergency registration indicator and / or emergency registration time information. For the description of the emergency registration indicator and emergency registration time information, refer to Step 708. Details will not be described again here.

[0403] Step 711: The remote terminal performs the relay selection.

[0404] The implementation method of Step 711 is the same as that of Step 610. Reference may be made to the description of Step 610. Details will not be described again here.

[0405] In Example 2, when the network accessed by the relay terminal supports the emergency service, the PCF determines to provide the relay terminal with the RSC for the emergency service. When the network accessed by the relay terminal does not support the emergency service, the PCF does not provide the relay terminal with the RSC for the emergency service. Therefore, the relay terminal does not participate in the relay discovery procedure where the emergency service is supported. This helps to avoid the case where the relay terminal discovered by the remote terminal does not support the emergency service. Furthermore, according to the method shown in Example 2, the decision logic of the relay terminal can be simplified.

[0406] Example 3

[0407] FIG. 8 is a diagram of a communication method 800 according to this application.

[0408] The steps in method 800 may be steps executed after the remote terminal selects a relay terminal. For example, as shown in FIG. 8, the steps in method 800 may be executed after the procedures of Example 1 or Example 2.

[0409] Step 801: The remote terminal directly sends a communication request message to the relay terminal.

[0410] Correspondingly, the relay terminal receives a direct communication request message from the remote terminal.

[0411] The direct communication request message includes an identifier of the remote terminal and an RSC. The identifier of the remote terminal includes at least one of the following, namely, the subscription permanent identifier (SUPI) of the remote terminal, the subscription concealed identifier (SUCI), the generic public subscription identifier (GPSI), the permanent equipment identifier (PEI) or the mobile subscriber international ISDN / PSTN number (MSISDN), or an application layer identifier (for example, user information (user info)). ISDN is the Integrated Service Digital Network, and PSTN is the Public Switched Telephone Network. MSISDN may be understood as identification information that can be disclosed externally by the terminal, for example, the telephone number of the terminal. The RSC here is the RSC corresponding to the emergency service.

[0412] Step 802: After receiving the direct communication request message, the relay terminal sends an authorization request message to the AMF.

[0413] Correspondingly, the AMF receives the authorization request message from the relay terminal.

[0414] The authorization request message here may be a NAS message. The authorization request message includes the identifier of the remote terminal and the RSC. The authorization request message is used to request authorization for the remote terminal to access the service corresponding to the RSC. If the authorization is successful (success), this indicates that the remote terminal can access the service corresponding to the RSC, or if the authorization fails (failure), this indicates that the remote terminal cannot access the service corresponding to the RSC. The RSC here is the RSC carried in the direct communication request message.

[0415] Optionally, when it is determined that the RSC in the direct communication request message corresponds to an emergency service, the relay terminal sends an authorization request message to the AMF to request authorization for the remote terminal to access the service corresponding to the RSC.

[0416] Step 803: The AMF sends the authorization request message to the authorization network element.

[0417] Correspondingly, the authorization network element receives the authorization request message from the AMF.

[0418] The authorization request message here includes the identifier of the remote terminal and the RSC. The authorization request message is used to request authorization for the remote terminal to access the service corresponding to the RSC. The RSC here is the RSC carried in the authorization request message from the AMF.

[0419] The specific type of the authorization network element is not limited in this application. For example, the authorization network element may be a UDM, a PCF, or an AUSF.

[0420] Step 804: The authorization network element sends an authorization response message to the AMF.

[0421] Correspondingly, the AMF receives the authorization response message from the authorization network element.

[0422] The authorization response message includes an authorization result. The authorization result includes authorization success or authorization failure. If the authorization result is authorization success, this indicates that the remote terminal can access the service corresponding to the RSC, or if the authorization result is authorization failure, this indicates that the remote terminal cannot access the service corresponding to the RSC.

[0423] In a possible implementation, the authorization network element stores the subscription data of the remote terminal, and the authorization network element authorizes the remote terminal to access the service corresponding to the RSC based on the subscription data of the remote terminal. The subscription data of the remote terminal includes whether the remote terminal is permitted to access emergency services or whether the remote terminal is permitted to access the service corresponding to the RSC.

[0424] Step 805: The AMF sends the authorization response message to the relay terminal.

[0425] Correspondingly, the relay terminal receives the authorization response message from the AMF.

[0426] The authorization response message includes an authorization result. The authorization result includes authorization success or authorization failure. If the authorization result is authorization success, this indicates that the remote terminal can access the service corresponding to the RSC, or if the authorization result is authorization failure, this indicates that the remote terminal cannot access the service corresponding to the RSC.

[0427] Step 806: The relay terminal determines whether to establish a PC5 connection to the remote terminal based on the authorization result.

[0428] Specifically, if the authorization result is authorization success, the relay terminal determines to establish a PC5 connection to the remote terminal. If the authorization result is authorization failure, the relay terminal determines not to establish a PC5 connection to the remote terminal.

[0429] Step 807: If it is determined to establish a PC5 connection to the remote terminal, the relay terminal sends a direct communication acceptance message to the remote terminal.

[0430] Correspondingly, the remote terminal receives a direct communication acceptance message from the relay terminal.

[0431] Step 808: If it is determined not to establish a PC5 connection to the remote terminal, the relay terminal sends a direct communication rejection message to the remote terminal.

[0432] Correspondingly, the remote terminal receives a direct communication rejection message from the relay terminal.

[0433] Optionally, the direct communication rejection message includes a cause value, and the cause value is authorization failure.

[0434] Optionally, method 800 further includes step 809.

[0435] Step 809: The relay terminal sends the first information to the AMF.

[0436] Correspondingly, the AMF receives the first information from the relay terminal.

[0437] The first information indicates that the relay service of the relay terminal is used for emergency services. That is, the relay terminal notifies the network that the relay terminal is processing, executing, or relaying emergency services.

[0438] Optionally, the first information may be carried in a service request message, a PDU session establishment message, or a registration message.

[0439] For example, when method 800 is applied to a layer 2 relay scenario, method 800 may include step 809. Clearly, when method 800 is applied to other relay scenarios (e.g., a layer 3 relay scenario), method 800 may also include step 809.

[0440] It should be noted that the opportunity to execute step 809 is not limited in this application.

[0441] For example, the relay terminal executes step 809 in an authorization procedure where the remote terminal is authorized to access an emergency service (e.g., as shown in FIG. 8, step 809 may be executed after step 802).

[0442] In other examples, the relay terminal starts step 809 after executing step 801.

[0443] In other examples, the relay terminal starts step 809 after executing step 806.

[0444] In other examples, the relay terminal starts step 809 after receiving a discovery message (model B) of the remote terminal.

[0445] In other examples, the relay terminal starts step 809 after receiving a discovery message (model B) of the remote terminal and determining that the network accessed by the relay terminal supports an emergency service.

[0446] In other examples, the relay terminal starts step 809 after transmitting a discovery message (model A).

[0447] In Example 3, the relay terminal establishes a PC5 connection to the remote terminal and provides a relay service for the emergency service to the remote terminal only after determining that the remote terminal is authorized to access the emergency service. This helps to avoid unauthorized access of the remote terminal to the emergency service.

[0448] As described above, with reference to FIGS. 4 to 8, the method provided in this application has been described in detail. Hereinafter, with reference to FIGS. 9 and 10, embodiments of the apparatus of this application will be described in detail.

[0449] To implement the functions in the above embodiments, it can be understood that the apparatus in FIG. 9 or FIG. 10 includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should easily recognize that in this application, the units and method steps in the examples described with reference to the embodiments disclosed in this application may be implemented by hardware or a combination of hardware and computer software. Whether the function is executed by hardware or by hardware driven by computer software depends on the specific application scenario and design constraints of the technical solution.

[0450] FIGS. 9 and 10 are diagrams of the structures of possible apparatuses according to embodiments of this application. The apparatus may be configured to implement the functions of the relay terminal, the policy control function network element, the remote terminal, or the application function network element in the above method embodiments, and thus may also achieve the beneficial effects of the above method embodiments.

[0451] As shown in FIG. 9, the apparatus 900 includes a transceiver unit 910 and a processing unit 920.

[0452] In some implementation manners, when the device 900 is configured to implement the function of the relay terminal in the above method embodiment, the processing unit 920 is configured to determine that the network accessed by the relay terminal supports the emergency service. The transceiver unit 910 is configured to send a first message, and the first message is used for the remote terminal to discover the relay terminal.

[0453] The first message is a first discovery message, and the first discovery message includes a relay service code corresponding to the emergency service, or the first message is a response message, and the response message is used to respond to the second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to the emergency service.

[0454] Optionally, the processing unit 920 is specifically configured to determine that the network accessed by the relay terminal supports the emergency service when at least one of the following conditions is met. Whether the relay terminal has received an emergency service support indicator from an access and mobility management function network element or an access network device, whether the relay terminal stores an emergency service support indicator, or whether the relay terminal has established an emergency protocol data unit PDU session.

[0455] The emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service.

[0456] Optionally, the relay terminal is in an emergency registration state, and the first message includes an emergency registration indicator and / or emergency registration time information. The emergency registration indicator indicates that the relay terminal is in an emergency registration state, and the emergency registration time information indicates the time or remaining time when the relay terminal is in an emergency registration state.

[0457] Optionally, the transceiver unit 910 is further configured to receive first configuration information from a policy control function network element, the first configuration information including a relay service code corresponding to an emergency service.

[0458] Optionally, the first configuration information further includes a priority of the relay service code corresponding to the emergency service, and the processing unit 920 is further configured to maintain or release a connection between the relay terminal and the remote terminal based on the priority, the connection being used for transmission of the emergency service.

[0459] Optionally, the transceiver unit 910 is further configured to receive a direct communication request message directly from a remote terminal, the direct communication request message being used to request establishment of a direct communication connection, the direct communication connection being used for transmission of the emergency service, and is further configured to send a second message to an access and mobility management function network element, the second message being used to request authorization for the remote terminal to access the emergency service, receive an authorization result from the access and mobility management function network element, and if the authorization result indicates that the remote terminal has successfully been authorized to access the emergency service, send a direct communication acceptance message to the remote terminal, or if the authorization result indicates that the remote terminal has failed to be authorized to access the emergency service, send a direct communication rejection message to the remote terminal.

[0460] Optionally, the transceiver unit 910 is further configured to receive a second discovery message from the remote terminal and transmit the second message to an access and mobility management function network element, the second message being used to request authorization for the remote terminal to access emergency services, and further configured to receive an authorization result from the access and mobility management function network element. The processing unit 920 is specifically configured to determine that the network accessed by the relay terminal supports emergency services when the authorization result indicates that the remote terminal has successfully obtained authorization to access emergency services.

[0461] Optionally, before determining that the network accessed by the relay terminal supports emergency services, the transceiver unit 910 is further configured to receive a second discovery message from the remote terminal. After determining that the network accessed by the relay terminal supports emergency services, the transceiver unit 910 is further configured to transmit the second message to an access and mobility management function network element, the second message being used to request authorization for the remote terminal to access emergency services, and further configured to receive an authorization result from the access and mobility management function network element. The transceiver unit 910 is specifically configured to transmit a response message to the remote terminal when the authorization result indicates that the remote terminal has successfully obtained authorization to access emergency services.

[0462] Optionally, the transceiver unit 910 is further configured to transmit first information to an access and mobility management function network element, the first information indicating that the relay service of the relay terminal is used for emergency services.

[0463] In some other implementation manners, when the apparatus 900 is configured to implement the functions of the relay terminal in the above method embodiments, the processing unit 920 is configured to generate a first message, the relay terminal is in an emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicates that the relay terminal is in an emergency registration state, and the emergency registration time information indicates the time or remaining time when the relay terminal is in an emergency registration state. The transceiver unit 910 is configured to transmit the first message, and the first message is used for the remote terminal to discover the relay terminal.

[0464] The first message is a first discovery message, the first discovery message includes a relay service code corresponding to an emergency service, or the first message is a response message, the response message is used to respond to a second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to an emergency service.

[0465] Optionally, the transceiver unit 910 is further configured to receive first configuration information from a policy control function network element, and the first configuration information includes a relay service code corresponding to an emergency service.

[0466] Optionally, the first configuration information further includes the priority of the relay service code corresponding to the emergency service. The processing unit 920 is further configured to maintain or release the connection between the relay terminal and the remote terminal based on the priority of the relay service code corresponding to the emergency service, and the connection is used for the transmission of the emergency service.

[0467] Optionally, the transceiver unit 910 is further configured to receive a direct communication request message directly from a remote terminal, the direct communication request message being used to request establishment of a direct communication connection, the direct communication connection being used for transmission of an emergency service, and is further configured to send a second message to an access and mobility management function network element, the second message being used to request authorization for the remote terminal to access the emergency service, receive an authorization result from the access and mobility management function network element, and if the authorization result indicates that the remote terminal has successfully been authorized to access the emergency service, send a direct communication acceptance message to the remote terminal, or if the authorization result indicates that the remote terminal has failed to be authorized to access the emergency service, send a direct communication rejection message to the remote terminal.

[0468] Optionally, the transceiver unit 910 is further configured to receive a second discovery message from a remote terminal and send a second message to an access and mobility management function network element, the second message being used to request authorization for the remote terminal to access the emergency service, and is further configured to receive an authorization result from the access and mobility management function network element. The transceiver unit 910 is specifically configured to send a response message to the remote terminal when the authorization result indicates that the remote terminal has successfully been authorized to access the emergency service.

[0469] Optionally, the transceiver unit 910 is further configured to send first information to an access and mobility management function network element, the first information indicating that the relay service of the relay terminal is used for the emergency service.

[0470] When the device 900 is configured to implement the functions of the PCF in the above method embodiment, the transceiver unit 910 or the processing unit 920 is configured to obtain a relay service code corresponding to an emergency service. The transceiver unit 910 is configured to transmit first configuration information to the relay terminal, and the first configuration information includes a relay service code corresponding to an emergency service.

[0471] Optionally, the first configuration information further includes the priority of the relay service code corresponding to the emergency service.

[0472] Optionally, when the network accessed by the relay terminal supports an emergency service, it is specifically configured to transmit the first configuration information to the relay terminal.

[0473] Optionally, the processing unit 920 is further configured to determine that the network accessed by the relay terminal supports an emergency service when at least one of the following conditions is met. Whether the policy control function network element has received an emergency service support indicator from the access and mobility management function network element, or whether the policy control function network element has stored or pre-configured the emergency service support indicator.

[0474] The emergency service support indicator indicates that the network accessed by the relay terminal supports an emergency service.

[0475] Optionally, the transceiver unit 910 is further configured to transmit second configuration information to the remote terminal, and the second configuration information includes a relay service code corresponding to an emergency service.

[0476] Optionally, the second configuration information further includes the priority of the relay service code corresponding to the emergency service.

[0477] Optionally, the transceiver unit 910 is specifically configured to obtain a relay service code for emergency services from an application function network element.

[0478] When the device 900 is configured to implement the functions of a remote terminal in the above-described method embodiments, the transceiver unit 910 is configured to receive a first message from a first relay terminal, the first message being used by the remote terminal to discover the first relay terminal, the first message including an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicating that the first relay terminal is in an emergency registration state, and the emergency registration time information indicating the time or remaining time that the first relay terminal has been in the emergency registration state. The processing unit 920 is configured to select a relay terminal based on the first message.

[0479] The first message is a first discovery message, the first discovery message including a relay service code for emergency services, or the first message is a response message, the response message being used to respond to a second discovery message transmitted by the remote terminal, the second discovery message including a relay service code for emergency services.

[0480] Optionally, the transceiver unit 910 is further configured to receive second configuration information from a policy control function network element, the second configuration information including a relay service code for emergency services.

[0481] Optionally, the second configuration information further includes the priority of the relay service code for emergency services. The processing unit 920 is further configured to maintain or release the connection between the remote terminal and the relay terminal based on the priority of the relay service code for emergency services, the connection being used for the transmission of emergency services.

[0482] When the apparatus 900 is configured to implement the AF function in the above-described method embodiment, the processing unit 920 is configured to determine a relay service code corresponding to an emergency service, and the transceiver unit 910 is configured to transmit the relay service code corresponding to the emergency service to a policy control function network element.

[0483] For a more detailed description of the transceiver unit 910 and the processing unit 920, refer to the relevant description in the above-described method embodiment. Details are not described again here.

[0484] As shown in FIG. 10, the apparatus 1000 includes a processor 1010. The processor 1010 is coupled to a memory 1030, and the memory 1030 is configured to store instructions. When the apparatus 1000 is configured to implement the above-described method, the processor 1010 is configured to execute instructions in the memory 1030 to implement the functions of the above-described processing unit 920.

[0485] Optionally, the apparatus 1000 further includes a memory 1030.

[0486] Optionally, the apparatus 1000 further includes an interface circuit 1020. The processor 1010 and the interface circuit 1020 are coupled to each other. It can be understood that the interface circuit 1020 may be a transceiver or an input / output interface. When the apparatus 1000 is configured to implement the above-described method, the processor 1010 is configured to execute instructions to implement the functions of the above-described processing unit 920, and the interface circuit 1020 is configured to implement the functions of the above-described transceiver unit 910.

[0487] For example, when the device 1000 is a chip used in a relay terminal, the chip realizes the functions of the relay terminal in the embodiments of the above method. The chip receives information from other modules (such as a radio frequency module or an antenna) within the relay terminal, and the information is transmitted to the relay terminal by other devices, or alternatively, the chip transmits the information to other modules (such as a radio frequency module or an antenna) within the relay terminal, and the information is transmitted to other devices by the relay terminal.

[0488] For example, when the device 1000 is a chip used in a policy control function network element, the chip realizes the functions of the policy control function network element in the embodiments of the above method. The chip receives information from other modules (such as a radio frequency module or an antenna) within the policy control function network element, and the information is transmitted to the policy control function network element by other devices, or alternatively, the chip transmits the information to other modules (such as a radio frequency module or an antenna) within the policy control function network element, and the information is transmitted to other devices by the policy control function network element.

[0489] For example, when the device 1000 is a chip used in a remote terminal, the chip realizes the functions of the remote terminal in the embodiments of the above method. The chip receives information from other modules (such as a radio frequency module or an antenna) within the remote terminal, and the information is transmitted to the remote terminal by other devices, or alternatively, the chip transmits the information to other modules (such as a radio frequency module or an antenna) within the remote terminal, and the information is transmitted to other devices by the remote terminal.

[0490] For example, when the device 1000 is a chip used in an application function network element, the chip realizes the functions of the application function network element in the above method embodiments. The chip receives information from other modules (such as a radio frequency module or an antenna) within the application function network element, and the information is transmitted to the application function network element by other devices, or alternatively, the chip transmits the information to other modules (such as a radio frequency module or an antenna) within the application function network element, and the information is transmitted to other devices by the application function network element.

[0491] This application further provides a communication device including a processor. The processor is coupled to a memory. The memory is configured to store a computer program or instructions and / or data. The processor is configured to execute the computer program or instructions stored in the memory, or read the data stored in the memory to execute the method in the above method embodiments. Optionally, there is one or more processors. Optionally, the communication device includes a memory. Optionally, there is one or more memories. Optionally, the memory and the processor are integrated together or arranged separately.

[0492] This application further provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions for realizing the method executed by the relay terminal, policy control function network element, remote terminal or application function network element in the above method embodiments.

[0493] This application further provides a computer program product including instructions. When the instructions are executed by a computer, the method executed by the relay terminal, policy control function network element, remote terminal or application function network element in the above method embodiments is realized.

[0494] This application further provides a communication system. The communication system includes at least one of the relay terminal, the policy control function network element, the remote terminal, or the application function network element in the above embodiments.

[0495] For the description of the relevant content and the beneficial effects of any one of the devices provided above, refer to the embodiments of the corresponding method provided above. Details are not described again here.

[0496] It can be understood that the processor in the embodiments of this application may be a central processing unit (CPU), or any other general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0497] The steps of the method in the embodiments of this application may be implemented by hardware or by a processor executing software instructions. The software instructions may include corresponding software modules. The software modules may be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a removable hard disk, a compact disc read-only memory (CD-ROM), or any other form of storage medium well-known in the art. For example, the storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Obviously, the storage medium may alternatively be a component of the processor. The processor and the storage medium may be located in an ASIC. Further, the ASIC may be located in a relay terminal, a policy control function network element, a remote terminal, or an application function network element. Obviously, the processor and the storage medium may alternatively exist as discrete components in a relay terminal, a policy control function network element, a remote terminal, or an application function network element.

[0498] All or part of the above embodiments may be implemented by software, hardware, firmware, or any combination thereof. When software is used to implement an embodiment, all or part of the embodiment may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, all or part of the procedures or functions in the embodiments of this application are executed. The computer may be a general-purpose computer, a dedicated computer, a computer network, a network device, a user device, or other programmable devices. The computer program or instructions may be stored in a computer-readable storage medium, or may be transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions may be transmitted in a wired or wireless manner from a website, computer, server, or data center to another website, computer, server, or data center. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device integrating one or more available media, such as a server or a data center. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape, an optical medium, such as a digital video disc, or a semiconductor medium, such as a solid state drive.

[0499] In the embodiments of this application, unless otherwise specified or logically inconsistent, the terms and / or descriptions in different embodiments are consistent and may be cross-referenced to each other. The technical features in different embodiments may be combined based on their internal logical relationships to form new embodiments.

[0500] It should be understood that the various numbers in the embodiments of this application are used merely for distinction to facilitate the description and are not used to limit the scope of the embodiments of this application. The sequence numbers of the above processes do not mean the execution order, and the execution order of the processes should be determined based on the functions and internal logics of the processes.

[0501] Unless otherwise specified, the meanings of all technical and scientific terms used in the embodiments of this application are the same as those commonly understood by those skilled in the art of this application. The terms used in this application are merely intended to describe specific embodiments and are not intended to limit the scope of this application. The above are examples for illustration, and it should be understood that the above examples are merely intended to help those skilled in the art understand the embodiments of this application and are not intended to limit the embodiments of this application to examples of specific values or specific scenarios. It is obvious that those skilled in the art can make various equivalent modifications or deformations based on the above examples, and such modifications and deformations also fall within the scope of the embodiments of this application.

[0502] The above description is merely a specific implementation manner of this application and is not intended to limit the protection scope of this application. Any deformation or substitution that can be easily conceived by those skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall follow the protection scope of the claims.

Claims

1. A communication method, comprising: a step of determining, by a relay terminal, that a network accessed by the relay terminal supports an emergency service; and a step of transmitting, by the relay terminal, a first message, wherein the first message is used for a remote terminal to discover the relay terminal. The method further comprises: wherein the first message is a first discovery message, and the first discovery message includes a relay service code corresponding to the emergency service; or the first message is a response message, and the response message is used to respond to a second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to the emergency service.

2. The step of determining, by the relay terminal, that the network accessed by the relay terminal supports the emergency service includes: when at least one of the following conditions is satisfied: the relay terminal receives an emergency service support indicator from an access and mobility management function network element or an access network device; the relay terminal stores an emergency service support indicator; or the relay terminal has established an emergency protocol data unit (PDU) session. The step of determining, by the relay terminal, that the network accessed by the relay terminal supports the emergency service is included. The emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service. The method according to claim 1.

3. The relay terminal is in an emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicates that the relay terminal is in the emergency registration state, and the emergency registration time information indicates the time and / or remaining time when the relay terminal is in the emergency registration state. The method according to claim 1 or 2.

4. The method further comprises: ​ A step of receiving, by the relay terminal, first configuration information from a policy control function network element, where the first configuration information includes the relay service code corresponding to the emergency service, and the method according to any one of claims 1 to 3 further includes this step.

5. The first configuration information further includes the priority of the relay service code corresponding to the emergency service. The method includes: A step of maintaining or releasing, by the relay terminal, a connection between the relay terminal and the remote terminal based on the priority, where the connection is used for transmission of the emergency service, and the method according to claim 4 further includes this step.

6. The method includes: A step of receiving, by the relay terminal, a direct communication request message from the remote terminal, where the direct communication request message is used to request establishment of a direct communication connection, and the direct communication connection is used for transmission of the emergency service, and A step of transmitting, by the relay terminal, a second message to the access and mobility management function network element, where the second message is used to request authorization for the remote terminal to access the emergency service, and A step of receiving, by the relay terminal, an authorization result from the access and mobility management function network element, and When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, a step of transmitting, by the relay terminal, a direct communication acceptance message to the remote terminal, or When the authorization result indicates that the remote terminal has failed to obtain authorization to access the emergency service, a step of transmitting, by the relay terminal, a direct communication rejection message to the remote terminal and the method according to any one of claims 1 to 5 further includes this step.

7. The method includes: A step of receiving, by the relay terminal, the second discovery message from the remote terminal, and A step of transmitting, by the relay terminal, a second message to the access and mobility management function network element, where the second message is used to request authorization for the remote terminal to access the emergency service. receiving, by the relay terminal, an authorization result from the access and mobility management function network element further comprising The step of determining, by the relay terminal, that the network accessed by the relay terminal supports an emergency service The method according to any one of claims 1 to 5, further comprising, when the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, determining, by the relay terminal, that the network accessed by the relay terminal supports the emergency service

8. Before determining, by the relay terminal, that the network accessed by the relay terminal supports an emergency service, the method further comprises receiving, by the relay terminal, the second discovery message from the remote terminal After determining, by the relay terminal, that the network accessed by the relay terminal supports an emergency service, the method further comprises transmitting, by the relay terminal, a second message to the access and mobility management function network element, the second message being used to request authorization for the remote terminal to access the emergency service receiving, by the relay terminal, an authorization result from the access and mobility management function network element further comprising The step of transmitting, by the relay terminal, a first message The method according to any one of claims 1 to 5, further comprising, when the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, transmitting, by the relay terminal, the response message to the remote terminal

9. The method further comprises transmitting, by the relay terminal, first information to the access and mobility management function network element, the first information indicating that the relay service of the relay terminal is used for the emergency service, according to the method of any one of claims 1 to 8

10. The method further comprises A step of receiving, by the relay terminal, a seventh message from the remote terminal, where the seventh message is used to request establishing a connection to the relay terminal, and the connection is used for transmission of the emergency service After receiving the seventh message, if the relay terminal does not have an emergency protocol data unit (PDU) session, a step of requesting, by the relay terminal, to establish the emergency PDU session The method according to any one of claims 1 to 8, further comprising

11. The method according to claim 10, wherein the seventh message is a direct communication request message

12. A communication method, comprising A step of obtaining, by a policy control function network element, a relay service code corresponding to an emergency service A step of transmitting, by the policy control function network element, first configuration information to a relay terminal, where the first configuration information includes the relay service code corresponding to the emergency service A method comprising

13. The method according to claim 12, wherein the first configuration information further includes a priority of the relay service code corresponding to the emergency service

14. The step of transmitting, by the policy control function network element, the first configuration information to the relay terminal The method according to claim 12 or 13, wherein the step of transmitting, by the policy control function network element, the first configuration information to the relay terminal includes a step of transmitting, by the policy control function network element, the first configuration information to the relay terminal when a network accessed by the relay terminal supports the emergency service

15. The method includes In the following cases, that is When the policy control function network element receives an emergency service support indicator from an access and mobility management function network element, or When the policy control function network element stores or pre-configures an emergency service support indicator When at least one of the above is satisfied, the method further includes a step of determining, by the policy control function network element, that the network accessed by the relay terminal supports the emergency service The method according to claim 14, wherein the emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service.

16. The method further includes: a step of transmitting, by the policy control function network element, second configuration information to a remote terminal, where the second configuration information includes the relay service code corresponding to the emergency service, according to any one of claims 12 to 15.

17. The method according to claim 16, wherein the second configuration information further includes the priority of the relay service code corresponding to the emergency service.

18. The step of obtaining, by the policy control function network element, a relay service code corresponding to an emergency service includes: a step of obtaining, by the policy control function network element, the relay service code corresponding to the emergency service from an application function network element, according to any one of claims 12 to 17.

19. A communication method, comprising: a step of receiving, by a remote terminal, a first message from a first relay terminal, where the first message is used by the remote terminal to discover the first relay terminal, the first message includes an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicates that the first relay terminal is in an emergency registration state, and the emergency registration time information indicates the time and / or remaining time when the first relay terminal is in the emergency registration state; a step of selecting, by the remote terminal, a relay terminal based on the first message; and wherein the first message is a first discovery message, the first discovery message includes a relay service code corresponding to an emergency service, or the first message is a response message, the response message is used to respond to a second discovery message transmitted by the remote terminal, and the second discovery message includes a relay service code corresponding to an emergency service.

20. The method further includes: The step of receiving, by the remote terminal, second configuration information from a policy control function network element, where the second configuration information includes the relay service code corresponding to the emergency service, the method according to claim 19 further comprising this step.

21. The second configuration information further includes the priority of the relay service code corresponding to the emergency service, The method includes: The step of maintaining or releasing the connection between the remote terminal and the relay terminal by the remote terminal based on the priority of the relay service code corresponding to the emergency service, where the connection is used for the transmission of the emergency service, the method according to claim 20 further comprising this step.

22. A communication method, comprising: The step of generating, by a relay terminal, a first message, where the relay terminal is in an emergency registration state, the first message includes an emergency registration indicator and / or emergency registration time information, the emergency registration indicator indicates that the relay terminal is in the emergency registration state, and the emergency registration time information indicates the time and / or remaining time when the relay terminal is in the emergency registration state; The step of transmitting, by the relay terminal, the first message, where the first message is used for the remote terminal to discover the relay terminal; and The first message is a first discovery message, the first discovery message includes a relay service code corresponding to an emergency service, or the first message is a response message, the response message is used to respond to a second discovery message from the remote terminal, and the second discovery message includes a relay service code corresponding to an emergency service.

23. The method includes: The step of receiving, by the relay terminal, first configuration information from a policy control function network element, where the first configuration information includes the relay service code corresponding to the emergency service. The method according to claim 22 further comprising this step.

24. The first configuration information further includes the priority of the relay service code corresponding to the emergency service, The method includes: The step of maintaining or releasing a connection between the relay terminal and the remote terminal by the relay terminal based on the priority of the relay service code corresponding to the emergency service, wherein the connection is used for transmission of the emergency service, further includes the step of, the method according to claim 23.

25. The method includes: The step of receiving, by the relay terminal, a direct communication request message directly from the remote terminal, wherein the direct communication request message is used to request establishment of a direct communication connection, and the direct communication connection is used for transmission of the emergency service, and The step of transmitting, by the relay terminal, a second message to an access and mobility management function network element, wherein the second message is used to request authorization for the remote terminal to access the emergency service, and The step of receiving, by the relay terminal, an authorization result from the access and mobility management function network element, and When the authorization result indicates that the remote terminal has successfully obtained authorization to access the emergency service, the step of transmitting, by the relay terminal, a direct communication acceptance message to the remote terminal, or When the authorization result indicates that the remote terminal has failed to obtain authorization to access the emergency service, the step of transmitting, by the relay terminal, a direct communication rejection message to the remote terminal further includes the method according to any one of claims 22 to 24.

26. The method includes: The step of receiving, by the relay terminal, the second discovery message from the remote terminal, and The step of transmitting, by the relay terminal, a second message to an access and mobility management function network element, wherein the second message is used to request authorization for the remote terminal to access the emergency service, and The step of receiving, by the relay terminal, an authorization result from the access and mobility management function network element further includes, The step of transmitting, by the relay terminal, the first message is The method according to any one of claims 22 to 24, further comprising: when the authorization result indicates that the remote terminal has successfully accessed the emergency service, the relay terminal transmits the response message to the remote terminal.

27. The method comprises: a step of the relay terminal transmitting first information to the access and mobility management function network element, wherein the first information indicates that the relay service of the relay terminal is used for the emergency service, the method according to any one of claims 22 to 26.

28. The method comprises: a step of the relay terminal receiving a seventh message from the remote terminal, wherein the seventh message is used to request establishing a connection to the relay terminal, and the connection is used for transmission of the emergency service; and after receiving the seventh message, when the relay terminal does not have an emergency protocol data unit (PDU) session, a step of the relay terminal requesting to establish the emergency PDU session the method according to any one of claims 22 to 27.

29. The method according to claim 28, wherein the seventh message is a direct communication request message.

30. A communication device, comprising: a processor configured to execute a computer program stored in a memory, enabling the device to execute the method according to any one of claims 1 to 11, execute the method according to any one of claims 12 to 18, execute the method according to any one of claims 19 to 21, or execute the method according to any one of claims 22 to 29.

31. The device according to claim 30, further comprising a memory.

32. A computer-readable storage medium, The computer-readable storage medium stores a computer program, and when the computer program is executed on a computer, the computer is capable of executing the method according to any one of claims 1 to 11, executing the method according to any one of claims 12 to 18, executing the method according to any one of claims 19 to 21, or executing the method according to any one of claims 22 to 29. A computer-readable storage medium.

33. A computer program product, wherein the computer program product includes instructions for use in executing the method according to any one of claims 1 to 11, or includes instructions for use in executing the method according to any one of claims 12 to 18, or includes instructions for use in executing the method according to any one of claims 19 to 21, or includes instructions for use in executing the method according to any one of claims 22 to 29. A computer program product.

34. A communication system including a relay terminal and a remote terminal, wherein the relay terminal is configured to execute the method according to any one of claims 1 to 11. A system.

35. The remote terminal is configured to execute the method according to any one of claims 19 to 21. The system according to claim 34.

36. The communication system further includes a policy control function network element, wherein the policy control function network element is configured to execute the method according to any one of claims 12 to 18. The system according to claim 34 or 35.

37. A communication system including a relay terminal and a remote terminal, wherein the relay terminal is configured to execute the method according to any one of claims 22 to 29, and the remote terminal is configured to execute the method according to any one of claims 18 to 21. A system.

38. The communication system further includes a policy control function network element, wherein the policy control function network element is configured to execute the method according to any one of claims 14 to 18. A system.

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