Communication methods and communication devices

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] [ Technical Field Embodiments of this application relate to the field of communications, and more specifically, to communication methods and communication devices.

Background Art

[0002] With the rapid development of mobile communications, the widespread 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, thereby 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. The 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 the 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 the first embodiment, a communication method is provided. This method may be performed by a relay terminal, or by a module or unit within a relay terminal. For ease of explanation, the term "relay terminal" will be used as a unified term below.

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

[0008] The emergency services referred to here may be general service types (which may also be called emergency service types) or specific emergency services.

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

[0010] Optionally, a relay terminal sending the first message includes the following: The relay terminal sends the first message when the network accessed by the relay terminal supports emergency services. Alternatively, in other descriptions, the relay terminal sends the first message after it has determined that the network accessed by the relay terminal supports emergency services.

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

[0012] Optionally, before the relay terminal determines that the network accessed by the relay terminal supports emergency services, the method further includes: The relay terminal determines that the first message contains a relay service code corresponding to an 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 decide whether the network accessed by the relay terminal supports an emergency service. If the relay service code included in the first message does not correspond to an emergency service, the relay terminal does not need to decide whether the network accessed by the relay terminal supports an emergency service.

[0014] Referring to the first aspect, in a possible implementation, a relay terminal's determination that the network accessed by the relay terminal supports emergency services includes: A relay terminal determines that the network accessed by the relay terminal supports emergency services when at least one of the following conditions is met: The relay terminal has received an emergency service support indicator from an access and mobility management function network element or access network device; 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] Referencing either the first embodiment or an implementation of the first embodiment, in other possible implementations, 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 indicating that the relay terminal is in an emergency registration state, and the emergency registration time information indicating the time or remaining time that the relay terminal has been in an emergency registration state.

[0016] The technical solutions described above help the remote terminal select a more suitable relay terminal. For example, the remote terminal may preferentially select a relay terminal that is in a non-urgent registration state. In another example, if all relay terminals sending discovery or response messages are in an urgent registration state, the remote terminal may preferentially select a relay terminal that has a longer remaining time in the urgent registration state.

[0017] Referencing either the first embodiment or an implementation of the first embodiment, other possible implementations include: a relay terminal receives first configuration information from a policy control function network element, 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 relay service code to respond to emergency services for relay terminals.

[0019] Referencing either the first embodiment or an implementation of the first embodiment, in other possible implementations, the first configuration information further includes priority of relay service codes corresponding to emergency services, the method further includes: a relay terminal maintains or releases a connection between the relay terminal and a remote terminal based on priority, and the connection is used for the transmission of emergency services.

[0020] For example, a policy control function network element configures, for a relay terminal, multiple relay service codes, including relay service codes corresponding to emergency services, and the respective priorities of the multiple relay service codes, by using first configuration information. The relay terminal establishes multiple connections to remote terminals, and the multiple connections have a one-to-one correspondence with the multiple relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the relay terminal releases some of the established connections, for example, when the relay terminal's transmission resources or capacity are limited, the relay terminal may release connections with lower relay service code priorities from the multiple established connections.

[0021] The above technical solutions help relay terminals perform connection management.

[0022] Referencing either the first embodiment or an implementation of the first embodiment, other possible implementations further include: a relay terminal receives a direct communication request message from a remote terminal, the direct communication request message is used to request the establishment of a direct communication connection, the direct communication connection is used for the transmission of emergency services. The relay terminal transmits a second message to an access and mobility management function network element, the second message is used to request 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 been successfully authorized to access emergency services, the relay terminal transmits a direct communication accept 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 transmits a direct communication reject message to the remote terminal.

[0023] According to the technical solution described above, in the procedure for establishing a connection to a 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 the remote terminal with relay services for emergency services only when the remote terminal is authorized to access emergency services. In this way, it is ensured that the relay terminal selected by the remote terminal expecting to access emergency services can provide relay services for emergency services, and unauthorized access to emergency services by remote terminals is avoided.

[0024] Referencing either the first embodiment or an implementation of the first embodiment, other possible implementations further include: The relay terminal receives a second discovery message from the remote terminal. The relay terminal transmits the second message to an access and mobility management network element, which is used to request authorization for the remote terminal to access emergency services. The relay terminal receives an authorization result from the access and mobility management network element. The relay terminal's determination that the network accessed by the relay terminal supports emergency services includes: The relay terminal determines that the network accessed by the relay terminal supports emergency services when the authorization result indicates that the remote terminal has been successfully authorized to access emergency services.

[0025] In the above technical solution, after receiving a second discovery message from a remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access emergency services. If the network successfully authorizes the remote terminal to access emergency services, the relay terminal then further determines whether the network accessed by the relay terminal supports emergency services. Subsequently, the relay terminal may or may not send a response message to the second discovery message, depending on whether the network accessed by the relay terminal supports emergency services. In this way, it is ensured that the relay terminal selected by the remote terminal expecting to access emergency services can provide relay services for emergency services, and unauthorized access to emergency services by remote terminals is 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 emergency services, 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 emergency services, 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 emergency services. 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 emergency services, 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 emergency services, and when the network accessed by the relay terminal supports emergency services, further determines whether the network authorizes the remote terminal to access emergency services. Then, the relay terminal sends or does not send a response message to the second discovery message depending on whether the network authorizes the remote terminal 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.

[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 a PDU session establishment message carries first information, the first information indicates that the PDU session will be used for the transmission of emergency services. In this case, the access and mobility management function network element either selects a session management function network element capable of providing emergency services based on the first information, or 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 emergency services based on the first information.

[0033] Referencing either the first embodiment or an implementation of the first embodiment, other possible implementations further include: the relay terminal transmits second information to an access and mobility management function network element, the second information indicating that the relay terminal is withdrawing from providing emergency services to the remote terminal, or the second information indicating that the relay terminal will not provide emergency services to the remote terminal.

[0034] In other words, the relay terminal reports to the access and mobility management network element that it is not in a state to provide relay services for emergency services, or that it is not in a state to provide emergency services to remote terminals, and as a result, the access and mobility management network element restricts the relay terminal with respect to 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 relay terminal's context.

[0036] Optionally, the relay terminal transmitting second information to the access and mobility management network element includes: the relay terminal transmitting second information to the access and mobility management network element after releasing the connection used for transmitting emergency services, or, if the relay terminal no longer has a connection used for transmitting emergency services, the relay terminal transmitting second information to the access and mobility management network element.

[0037] Referencing either the first embodiment or an implementation of the first embodiment, other possible implementations further include: a relay terminal receives a seventh message from a remote terminal, the seventh message is used to request the establishment of a connection to the relay terminal, the connection is used for the transmission of emergency services. If the relay terminal does not have an emergency PDU session after receiving the seventh message, the relay terminal requests the establishment of an emergency PDU session. Furthermore, if the relay terminal has established an emergency PDU session, the relay terminal does not need to request the establishment of 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 embodiment, a communication method is provided. This method may be performed by a policy control function network element, or by a module or unit within the policy control function network element. For ease of explanation, the term "policy control function network element" will be used as a unified name below.

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

[0041] The emergency services referred to here may be general service types (which may also be called emergency service types) or specific emergency services.

[0042] In the above technical solution, the policy control function network element configures relay service code for emergency services for relay terminals, thereby enabling relay terminals to participate in emergency service relay discovery procedures and facilitate the transmission of emergency services in relay scenarios.

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

[0044] The above technical solutions help relay terminals perform connection management. For example, a policy control function network element configures multiple relay service codes, including relay service codes corresponding to emergency services, and the respective priorities of the multiple relay service codes, for a relay terminal by using first configuration information. A relay terminal establishes multiple connections to remote terminals, and the multiple connections have a one-to-one correspondence with multiple relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When a relay terminal releases some of its established connections, for example, when the relay terminal's transmission resources or capacity are limited, the relay terminal may release connections with lower relay service code priorities from among the multiple established connections.

[0045] Referencing either the second embodiment or an implementation of the second embodiment, in other possible implementations, the transmission of the first configuration information by the policy control function network element to the relay terminal includes: When the network accessed by the relay terminal supports emergency services, the policy control function network element transmits the first configuration information to the relay terminal.

[0046] According to the technical solution described above, the policy control network element provides the relay terminal with a relay service code corresponding to an emergency service 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 network element does not provide the relay terminal with a relay service code corresponding to the emergency service. Therefore, the relay terminal does not participate in the relay discovery procedure that supports 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 that the relay terminal selected by the remote terminal expecting to access the emergency service can provide relay services for the emergency service. This facilitates the transmission of emergency services in relay scenarios.

[0047] Referencing either the second aspect or an implementation of the second aspect, other possible implementations further include: The policy control function network element determines that the network accessed by the relay terminal supports emergency services when at least one of the following conditions is met: The policy control function network element has received an emergency services support indicator from the access and mobility management function network element, or the policy control function network element has stored or pre-configured an emergency services support indicator. The emergency services support indicator indicates that the network accessed by the relay terminal supports emergency services.

[0048] Referencing either the second embodiment or an implementation of the second embodiment, other possible implementations further include: a policy control function network element transmits a second configuration information to a remote terminal, the second configuration information including a relay service code corresponding to an emergency service.

[0049] In other words, the policy control function network element constitutes relay service code that responds to emergency services for remote terminals.

[0050] Referencing either the second embodiment or an implementation of the second embodiment, in other possible implementations, the second configuration information further includes the priority of relay service codes corresponding to emergency services.

[0051] The above technical solutions help the remote terminal perform connection management. For example, a policy control function network element configures multiple relay service codes, including relay service codes corresponding to emergency services, and the respective priorities of the multiple relay service codes, for the remote terminal by using second configuration information. The remote terminal establishes multiple connections to the relay terminal, and the multiple connections have a one-to-one correspondence with the multiple relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the remote terminal releases some of the established connections, for example, when the remote terminal's transmission resources or capacity are limited, the remote terminal may release connections with lower relay service code priorities from among the multiple established connections.

[0052] Referencing either the second embodiment or an implementation of the second embodiment, in other possible implementations, the acquisition of a relay service code corresponding to an emergency service by a policy control function network element includes: The policy control function network element acquires a relay service code corresponding to an emergency service from an application function network element.

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

[0054] According to a third aspect, a communication method is provided. This method may be performed by a remote terminal, or by a module or unit within a remote terminal. For ease of explanation, "remote terminal" will be used as a unified term below.

[0055] The method includes the following: A remote terminal receives 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 an emergency registration state. The remote terminal selects a relay terminal based on the first message. The first message is a first discovery message, the first discovery message including a relay service code corresponding to an emergency service, or the first message is a response message, the response message being used to respond to a second discovery message sent by the remote terminal, the second discovery message including a relay service code corresponding to an emergency service.

[0056] The technical solutions described above help the remote terminal select a more appropriate relay terminal, facilitating the transmission of emergency services in relay scenarios. For example, the remote terminal may preferentially select a relay terminal that is in a non-emergency registration state. In another example, if all relay terminals sending a discovery or response message are in an emergency registration state, the remote terminal may preferentially select a relay terminal that has a longer remaining time in the emergency registration state.

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

[0058] In other words, the policy control function network element constitutes relay service code that responds to emergency services for remote terminals.

[0059] Referencing either the third embodiment or an implementation of the third embodiment, in other possible implementations, the second configuration information further includes the priority of relay service codes corresponding to emergency services, and the method further includes: the remote terminal maintains or releases a connection between the remote terminal and the relay terminal based on the priority of relay service codes corresponding to emergency services, and the connection is used for the transmission of emergency services.

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

[0061] The above technical solutions help the remote terminal perform connection management.

[0062] According to a fourth aspect, a communication method is provided. This method may be performed by a relay terminal, or by a module or unit within a relay terminal. For ease of explanation, "relay terminal" will be used as a unified term below.

[0063] The method includes the following: A 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, and the emergency registration time information indicates the time or remaining time that the relay terminal has been in an emergency registration state. The relay terminal transmits a first message, the first message is used by a remote terminal to discover the relay terminal. 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 a remote terminal, the second discovery message includes a relay service code corresponding to an emergency service.

[0064] The technical solutions described above help the remote terminal select a more appropriate relay terminal, facilitating the transmission of emergency services in relay scenarios. For example, the remote terminal may preferentially select a relay terminal that is in a non-emergency registration state. In another example, if all relay terminals sending a discovery or response message are in an emergency registration state, the remote terminal may preferentially select a relay terminal that has a longer remaining time in the emergency registration state.

[0065] Referring to the fourth aspect, in possible implementations, the method further includes: a relay terminal receives first configuration information from a policy control function network element, 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 relay service code to respond to emergency services for relay terminals.

[0067] Referencing either the fourth embodiment or an implementation of the fourth embodiment, in other possible implementations, the first configuration information further includes the priority of relay service codes corresponding to emergency services, and the method further includes: a relay terminal maintains or releases a connection between the relay terminal and a remote terminal based on the priority of relay service codes corresponding to emergency services, and the connection is used for the transmission of emergency services.

[0068] For example, a policy control function network element configures, for a relay terminal, multiple relay service codes, including relay service codes corresponding to emergency services, and the respective priorities of the multiple relay service codes, by using first configuration information. The relay terminal establishes multiple connections to remote terminals, and the multiple connections have a one-to-one correspondence with the multiple relay service codes (for example, connection 1 corresponds to relay service code 1 (the context of connection 1 includes relay service code 1), connection 2 corresponds to relay service code 2 (the context of connection 2 includes relay service code 2)). When the relay terminal releases some of the established connections, for example, when the relay terminal's transmission resources or capacity are limited, the relay terminal may release connections with lower relay service code priorities from the multiple established connections.

[0069] The above technical solutions help relay terminals perform connection management.

[0070] Referencing either the fourth aspect or an implementation of the fourth aspect, other possible implementations further include: a relay terminal receives a direct communication request message from a remote terminal, the direct communication request message is used to request the establishment of a direct communication connection, the direct communication connection is used for the transmission of emergency services. The relay terminal transmits a second message to an access and mobility management function network element, the second message is used to request 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 been successfully authorized to access emergency services, the relay terminal transmits a direct communication accept 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 transmits a direct communication reject message to the remote terminal.

[0071] According to the technical solution described above, in the procedure for establishing a connection to a 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 the remote terminal with relay services for emergency services only when the remote terminal is authorized to access emergency services. This helps prevent unauthorized remote terminals from accessing emergency services.

[0072] Referencing either the fourth aspect or an implementation of the fourth aspect, other possible implementations further include: The relay terminal receives a second discovery message from the remote terminal. The relay terminal transmits the second message to the Access and Mobility Management Function Network Element, which is used to request 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. The relay terminal transmitting the first message includes: If the authorization result indicates that the remote terminal has been successfully authorized to access emergency services, the relay terminal transmits a response message to the remote terminal.

[0073] In the technical solution described above, after receiving a second discovery message from a remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access emergency services. If the network successfully authorizes the remote terminal to access emergency services, it sends a response message to the second discovery message. This helps prevent unauthorized remote terminal access to emergency services.

[0074] Referencing either the fourth aspect or an implementation of the fourth aspect, other possible implementations include: the relay terminal transmits first information to an access and mobility management function network element, the first information indicating that the relay service of the relay terminal is to be used for emergency services, or the first information indicating that the relay terminal provides emergency services to a remote terminal.

[0075] In other words, the relay terminal reports to the access and mobility management network element that it is providing relay services for emergency services, or that it is providing emergency services to a remote terminal, so that the access and mobility management network element does not restrict the relay terminal with respect to access management or mobility management. For example, the relay terminal may provide relay services in an unauthorized area.

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

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

[0078] Optionally, when a PDU session establishment message carries first information, the first information indicates that the PDU session will be used for the transmission of emergency services. In this case, the access and mobility management function network element either selects a session management function network element capable of providing emergency services based on the first information, or 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 emergency services based on the first information.

[0079] Referencing either the fourth aspect or an implementation of the fourth aspect, other possible implementations further include: the relay terminal transmits second information to an access and mobility management function network element, the second information indicating that the relay terminal is withdrawing from providing emergency services to the remote terminal, or the second information indicating that the relay terminal will not provide emergency services to the remote terminal.

[0080] In other words, the relay terminal reports to the access and mobility management network element that it is not in a state to provide relay services for emergency services, or that it is not in a state to provide emergency services to remote terminals, and as a result, the access and mobility management network element restricts the relay terminal with respect to access management or mobility management.

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

[0082] Optionally, the relay terminal transmitting second information to the access and mobility management network element includes: the relay terminal transmitting second information to the access and mobility management network element after releasing the connection used for transmitting emergency services, or, if the relay terminal no longer has a connection used for transmitting emergency services, the relay terminal transmitting second information to the access and mobility management network element.

[0083] Referencing either the fourth aspect or an implementation of the fourth aspect, other possible implementations further include: a relay terminal receives a seventh message from a remote terminal, the seventh message is used to request the establishment of a connection to the relay terminal, the connection is used for the transmission of emergency services. If the relay terminal does not have an emergency PDU session after receiving the seventh message, the relay terminal requests the establishment of an emergency PDU session. Furthermore, if the relay terminal has established an emergency PDU session, the relay terminal does not need to request the establishment of 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. This method may be performed by an application function network element, or by a module or unit within an application function network element. For ease of explanation, the term "application function network element" will be used as a unified name below.

[0086] The method includes the following: The application function network element determines the 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 technical solution described above, it is possible to ensure that relay service codes across different PLMNs are consistent. Therefore, inter-PLMN relay services used for emergency services can be better supported.

[0088] According to a sixth aspect, a communication device is provided. The device is configured to perform a method provided in either one of the above aspects or an implementation of the above aspects. Specifically, the device may include units and / or modules configured to perform a method provided in either one of the above aspects or an implementation of the above aspects, such as a processing unit and / or a communication unit.

[0089] In the implementation, 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, a transceiver is a transceiver circuit. Optionally, an input / output interface is an input / output circuit.

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

[0091] According to the 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 instructions stored in the memory and to perform a method provided in either of the above aspects or an implementation of the above aspects.

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

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

[0094] According to the 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 retrieve computer programs or instructions stored in memory through the communication interface and to execute a method provided in either the above aspect or an implementation of the above aspect. The communication interface may be implemented in hardware or software.

[0095] In this implementation, the device further includes memory.

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

[0097] Unless otherwise specified, or unless the operation is inconsistent with the actual function or internal logic of the operation in the relevant description, operations such as transmit and receive or input of a processor may be understood as such, or as such as transmit and receive operations performed by radio frequency circuits and antennas. This is not limited to 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 a method provided in any one of the above aspects or an implementation of the above aspects.

[0099] According to the eleventh aspect, a computer program product including instructions is provided. When the computer program product is executed on a computer, the computer becomes capable of performing the method provided in either the above aspect or the implementation of the above aspect.

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

[0101] Optionally, in the implementation, the chip further includes memory. The memory stores computer programs or instructions. The processor is configured to execute computer programs or instructions stored in memory. When a computer program or instruction is executed, the processor is configured to perform a method provided in either the above embodiment or the implementation of the above embodiment.

[0102] According to the 13th aspect, a communication system is provided, which includes at least one of the relay terminal, policy control function network element, remote terminal, or application function network element. [Brief explanation of the drawing]

[0103] [Figure 1] This is a diagram of a network architecture to which the technical solution of this application may be applied. [Figure 2] This is a diagram of another network architecture to which the technical solutions of this application may be applied. [Figure 3] This is a schematic flowchart for establishing a Layer 3 relay connection. [Figure 4] This is a diagram of the communication method 400 according to this application. [Figure 5] This is a diagram of the communication method 500 according to this application. [Figure 6] This is a diagram of the communication method 600 according to this application. [Figure 7] This is a diagram of the communication method 700 according to this application. [Figure 8] This is a diagram of the communication method 800 according to this application. [Figure 9] This is a diagram showing the structure of the apparatus according to an embodiment of this application. [Figure 10] This is a diagram of another structure of the apparatus according to an embodiment of this application. [Modes for carrying out the invention]

[0104] The technical solutions in this application are described below with reference to the attached drawings.

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

[0106] In this application, “to indicate” may include direct and indirect indication, or “to indicate” may be explicit and / or implicit. For example, when a statement indicates that certain information indicates information I, the information may directly indicate I or indirectly indicate I, but this does not mean that the information explicitly carries I. In other examples, implicit indication may be based on a location and / or resource used for transmission, and explicit indication may be based on one or more parameters, one or more indices and / or one or more bit patterns represented by the information.

[0107] The definitions of many features listed in this application are used simply to illustrate the function of the features by using examples. For detailed definitions, refer to the prior art.

[0108] In the following embodiments, the numbers 1, 2, 3, 4 and various others are used simply to distinguish them for the sake of clarity and are not used to limit the scope of the embodiments of this application, but rather, for example, to distinguish between different fields and different information.

[0109] "Pre-defined" may be implemented by pre-storing corresponding codes or tables in a device (e.g., including terminals or network devices), or by other means that can indicate relevant information. Specific implementations of pre-defined are 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] In embodiments of this application, “protocol” may be a standard protocol in the field of communications, and may include, for example, long-term evolution (LTE) protocols, new radio (radio NR) protocols, and related protocols applicable to future communications systems. This is not limited to this application.

[0111] The aspects, embodiments, or features presented in this application are described by describing systems comprising a plurality of 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 embodiments of this application, words such as “example” or “for example” are used to indicate that an example, illustration, or explanation is being given. No embodiment or design described as “example” in this application should be described as being preferable to or having more advantages than other embodiments or designs. More precisely, the use of the word “example” is intended to present a concept in a particular manner.

[0113] The terms “includes,” “possess,” and their variations, unless otherwise specifically emphasized, mean “includes, but not limited to.”

[0114] "At least one" means one or more, and "plural" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships are possible. For example, A and / or B may mean that only A exists, both A and B exist, or only B exists, and A and B may be singular or plural. The letter " / " usually indicates an "or" relationship between related objects. "At least one of the following items" or similar expressions means any combination of these items, including either a single item or a combination of multiple items. For example, at least one of a, b and c may mean 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 5th generation (5G) or NR systems, LTE systems, LTE frequency division duplex (FDD) systems, and LTE time division duplex (TDD) systems. The technical solutions provided in this application may be further applied to non-terrestrial network (NTN) communication systems, such as satellite communication systems. The technical solutions provided in this application may be further 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 be further applied to future communication systems, such as 6th generation mobile communication systems.

[0116] For example, Figure 1 is a diagram of a network architecture.

[0117] As shown in Figure 1, a 5G system (5th generation system, 5GS) is used as an example of a network architecture. The network architecture may include three parts: 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: 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 part other than the RAN portion may be called the core network portion.

[0118] In this application, user equipment, (wireless) access network devices, UPF network elements, AUSF network elements, AMF network elements, SMF network elements, NSSF network elements, NEF network elements, NRF network elements, PCF network elements, UDM network elements, and AF network elements are abbreviated as UE, (R)AN, UPF, AUSF, UDR, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, and AF, respectively.

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

[0120] 1.UE

[0121] In this application, the UE may also be called 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 ease of explanation, "terminal" will be used as a unified term below.

[0122] A terminal is a device that can access a network. Terminals and (R)AN may communicate with each other using air interface technology (e.g., NR or LTE technology). Terminals may also communicate with each other using air interface technology (e.g., NR or LTE technology). Terminals may include mobile phones, tablets, computers with wireless receiver functionality, virtual reality (VR) terminals, augmented reality (AR) terminals, terminals in satellite communications, terminals in integrated access and backhaul (IAB) link systems, terminals in Wi-Fi communication systems, terminals in industrial control, terminals in self-driving, terminals in telemedicine, terminals in smart grids, terminals in transportation safety, terminals in smart cities, terminals in smart homes, and the like.

[0123] The specific technologies and device configurations used by the UE are not limited to these embodiments of this application.

[0124] 2. (R)AN

[0125] In this application, (R)AN may be a device configured to communicate with a terminal, or 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 exchange, next generation NodeB (gNB) in a 5G mobile communication system, next generation NodeB in a 6th generation (6G) mobile communication system, a base station in a future mobile communication system, etc. Alternatively, the network device may be a module or unit that completes some of the functions of a base station, for example, 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 performs base station functions in D2D communication systems, V2X communication systems, M2M communication systems, and IoT communication systems. Alternatively, (R)AN may be a network device within NTN. In other words, (R)AN may be deployed on a high-altitude platform or satellite. (R)AN may be a macro base station, a micro base station or an indoor base station, or a relay node, donor node, etc.

[0127] The specific technologies, device types, and names used by (R)AN are not limited to the embodiments of this application. For ease of explanation, access network devices will be used hereafter as a unified name for (R)AN.

[0128] 3. UPF

[0129] The UPF is primarily responsible for transferring and receiving user data at terminals. For example, the UPF may receive user plane data from the DN and transmit it to the terminal via the access network device. The UPF may also receive user plane data from the terminal via the access network device and transfer it back to the DN. The transmission resources and scheduling functions used by the UPF network element to provide services to terminals are managed and controlled by the SMF.

[0130] 4.DN

[0131] DNs are primarily used as operator networks that provide data services to terminals, such as the Internet, third-party service networks, or IP multimedia service (IMS) networks.

[0132] 5. AUSF

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

[0134] 6. AMF

[0135] The AMF primarily handles signaling processes, such as access control, mobility management, attaching and detaching, and gateway selection. When providing services for a session at a terminal, the AMF provides control plane memory resources for the session, storing the session identifier, the SMF network element identifier associated with the session identifier, and so on.

[0136] 7. SMF

[0137] SMF is primarily responsible for user plane network element selection, user plane network element redirection, Internet Protocol (IP) address assignment, bearer establishment, correction and release, and quality of service (QoS) control.

[0138] 8. NSSF

[0139] NSSF is primarily responsible for network slice selection, determining which network slice instances a terminal is permitted to access based on terminal slice selection support information, subscription information, etc.

[0140] 9.NEF

[0141] NEF primarily supports secure interaction between 3GPP networks and third-party applications.

[0142] 10. NRF

[0143] The NRF is primarily configured to store information such as network function entities and descriptions of services provided by those network function entities.

[0144] 11. PCF

[0145] PCF is primarily responsible for policy control decisions, providing policy rules for control plane functions, and traffic-based billing control functions.

[0146] 12. UDM

[0147] UDM is primarily responsible for managing device enrollment data, including storing and managing device identifiers and granting device access permissions.

[0148] 13.AF

[0149] An AF primarily interacts with the 3GPP core network to provide services, such as influencing data routing decisions, providing policy control functions, or supporting the provision of third-party services for the network. An AF may be an AF deployed within the operator network or a third-party AF.

[0150] In the network architecture shown in Figure 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; however, this is not limited to this application.

[0151] The network architecture described above is merely an illustrative example, and it should be understood that the network architectures applicable to the embodiments of this application are not limited thereto. Any network architecture capable of realizing the functions of the network elements described above is applicable to the embodiments of this application.

[0152] Functional or network elements such as AMF, SMF, UPF, PCF, UDM, AUSF, NSSF, NEF, NRF, and AF shown in Figure 1 may also be understood as network elements configured to perform different functions, and may, for example, be combined into network slices as needed. These network elements may be independent devices, integrated into the same device to perform different functions, network elements within a hardware device, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (e.g., 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 solely to facilitate the distinction between different functions and do not constitute any limitation to this application. This application does not preclude 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 terminology used in 5G, or other names may be used.

[0154] The technical solutions provided in this application may be applied to relay scenarios in which a remote terminal is connected to a network via a relay terminal.

[0155] For example, Figure 2 shows a network architecture in a relay scenario. The network architecture shown in Figure 2 may be based on, but is not limited to, the 5G architecture shown in Figure 1.

[0156] As shown in Figure 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 called a remote UE and is a terminal that obtains relay services, such as a wristwatch, a band, or an augmented reality (AR) headset / virtual reality (VR) headset. The relay terminal may also be called a relay UE and is a terminal that provides relay services, 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 the PC5 interface. The relay terminal may communicate with the UPF by using the relay terminal's PDU session, 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 the N6 interface.

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

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

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

[0160] Figure 3 is a schematic flowchart of the connection establishment process for Layer 3 relays.

[0161] In Layer 3 relay scenarios, remote terminals are described as remote UEs, and relay terminals are described as proximity-based service (ProSe) UE-to-NW relays. For brevity, the descriptions of remote and relay terminals are still used below.

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

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

[0164] The parameter information used for D2D communication includes the QoS mapping configuration, relay service code (RSC), and PDU session parameters corresponding to each RSC. The RSC identifies the relay connection (e.g., PC5 connection). For a relay terminal, the RSC may identify the connection service provided by the relay terminal for the 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: 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 a PDU session is established, the SMF may assign an IP address to the relay terminal, and the relay terminal may use the PDU session to transmit data between the relay terminal and the UPF. The PDU session may also 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 relay terminal perform the relay discovery procedure.

[0169] Remote terminals and relay terminals may discover each other through a relay discovery procedure. Two types of relay discovery procedures may exist, namely Model A and Model B.

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

[0171] The relay terminal actively transmits discovery messages (e.g., announcement messages), the remote terminal listens to and receives discovery messages, and the discovery messages include RSCs for connectivity services that can be provided by the relay terminal.

[0172] Thus, the remote terminal may perform a match 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 (Relay Service Center) of the connection services that can be provided by the relay terminal may be configured using a PCF (Peace-Controlled Function).

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

[0175] The remote terminal proactively sends a discovery message (e.g., a solicitation message), and the relay terminal listens for and receives the discovery message, which includes the RSC of the connection services expected by the remote terminal. The relay terminal may perform a comparison between the RSC of the connection services it can provide and the RSC in the discovery message. If the RSC of the connection services the relay terminal can provide 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] Thus, the remote terminal may select a relay terminal from one or more relay terminals to which it will send a response message.

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

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

[0179] PC5 is an interface between terminals, and PC5 connections are used for communication between terminals.

[0180] Optionally, the relay terminal decides 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 (e.g., the PDU session established in step 2) satisfies the session requirements of the remote terminal. If the PDU session established by the relay terminal does not satisfy 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 relay services, 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 the remote terminal an IP address to be used for PC5 communication.

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

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

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

[0185] Subsequently, the relay terminal may forward the uplink and downlink data of the remote terminal based on its IP address.

[0186] For example, suppose the IP address used by the remote terminal on the PC5 connection is IP3, the IP address corresponding to the relay terminal's PDU session is IP1, and the IP information assigned to the remote terminal by the relay terminal is IP1-1. In this way, the remote terminal sends data to the data network using IP3, the data network sends data to the remote terminal using IP1-1, and the relay terminal creates an association 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, sends the data to the UPF 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 explanation of Layer 3 relays, please refer to the prior art documentation. Further details will not be provided here.

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

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

[0190] The communication method provided in this application will be described in detail below with reference to the attached drawings.

[0191] The technical solution in this application is applicable to the transmission of abnormal services in relay scenarios. Abnormal services may be understood as services other than normal services. For example, abnormal services may be emergency services, multimedia priority services, or mission-critical services. This is not limited to these. The technical solution in this application will be described below using an example where the abnormal service is an emergency service. ru.

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

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

[0194] "Network" may include access networks and / or core networks. "Network supports emergency services" may be understood as access network devices and / or core network elements supporting emergency services. Access network devices and / or core network elements here may be any access network device and / or any core network device, any core network element and / or any access network device associated with a DN providing emergency services, or a core network element and / or access network device associated with a DN providing emergency services and configured to transmit emergency services to relay terminals. This is not limited to this application.

[0195] The fact that a network supports emergency services may be understood as the network supporting the transmission of emergency services, the network supporting the configuration or control of emergency services, or the network having the capacity or resources for the transmission of emergency services.

[0196] Emergency services may be general service types, or they may be called emergency service types. An emergency service type may include one or more emergency services. For example, an emergency service type may include emergency voice services, emergency video services, and emergency short message services. In this case, the network accessed by the relay terminal supporting emergency services may be understood as the network accessed by the relay terminal supporting any of the emergency services 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 a specific emergency service. For example, the network accessed by the relay terminal supports an emergency voice service.

[0198] In possible implementations, before the relay terminal determines that the network accessed by the relay terminal supports emergency services, Method 400 further includes: The relay terminal determines that the first message contains a relay service code corresponding to an emergency service.

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

[0200] This application describes many ways in which a relay terminal can determine whether the network it accesses supports emergency services. This is not limited to these methods.

[0201] In possible implementations, a relay terminal determines that the network it accesses supports emergency services if at least one of the following conditions is met: the relay terminal has received an emergency service support indicator from the AMF or access network device; the relay terminal has stored an emergency service support indicator; or the relay terminal has established an emergency PDU session.

[0202] In other possible implementations, a relay terminal determines that the network accessed by the relay terminal does not support emergency services if none of the following conditions are met: the relay terminal has received an emergency service support indicator from the AMF or access network device; the relay terminal has stored 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 emergency services.

[0204] Here, "emergency PDU session" may be understood as a PDU session used for transmitting emergency services, or as a PDU session corresponding to an emergency data network name (DNN).

[0205] Optionally, the relay terminal can be either a Layer 3 relay terminal or a Layer 2 relay terminal.

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

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

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

[0209] In possible implementations, the first message is the first discovery message, which 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 a description of the relay discovery procedure using Model A, see the relevant explanation in Figure 3. Further details will not be explained here again.

[0210] In other possible implementations, the first message is a response message, which is used to respond to a second discovery message from the remote terminal, the second discovery message containing a relay service code corresponding to an emergency service. For example, when the remote terminal and relay terminal use a relay discovery procedure using Model B, the first message is a response message. For a description of the relay discovery procedure using Model B, see the relevant explanation in Figure 3. Further details are not provided here.

[0211] An RSC for emergency service may be described as an RSC for emergency services, an RSC used for emergency services, or other alternatives.

[0212] Based on the different meanings of emergency services, the RSC (Responsible Service Center) that responds to emergency services may also have different meanings.

[0213] Specifically, when an emergency service is a service type, the RSC corresponding to an 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, suppose the emergency service type includes emergency voice service, emergency video service, and emergency short message service. In this case, the RSCs corresponding to emergency voice service, emergency video service, and emergency short message service are the same.

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

[0215] Optionally, when a 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 following: the time the relay terminal has been in an emergency registration state, the remaining time the relay terminal will be in an emergency registration state, or the time the relay terminal was in an emergency registration state. The time the relay terminal has been in an emergency registration state may be understood as the total time the relay terminal can maintain an emergency registration state.

[0216] For example, if the total time a relay terminal can maintain an emergency registration state is 5 seconds, the remaining time the relay terminal is in an emergency registration state is 3 seconds, and the time the relay terminal was in an emergency registration state is 2 seconds, the emergency registration time information may show at least one of 5 seconds, 3 seconds, or 2 seconds.

[0217] 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, a relay terminal being in an emergency registration state may be understood as the relay terminal being in the emergency registration process.

[0218] Optionally, method 400 further includes: The relay terminal generates or determines a 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 selects a relay terminal from among relay terminals that receive one or more first messages and send one or more first messages.

[0221] Optionally, one or more first messages received by a 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 a remote terminal selects a relay terminal from among relay terminals that send one or more first messages, the remote terminal assumes 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 following: the time the first relay terminal is in an emergency registration state, the remaining time the first relay terminal is in an emergency registration state, or the time the first relay terminal was in an emergency registration state.

[0222] For example, a remote terminal will prioritize selecting a relay terminal that is in a non-emergency registration state.

[0223] In another example, if all relay terminals sending the first message are in an emergency registration state, the remote terminal will prioritize selecting the relay terminal with the longest remaining time in the emergency registration state.

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

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

[0226] In possible implementations, step 401 is performed before step 402. Specifically, after the relay terminal determines that the network accessed by the relay terminal supports emergency services, the relay terminal sends a first message to the remote terminal.

[0227] In one example, if the relay terminal determines that the network it accesses supports emergency services, the relay terminal sends a first message to the remote terminal. For example, in a relay discovery procedure using Model A, if the relay terminal determines that the network it accesses supports emergency services, the relay terminal sends a first discovery message to the remote terminal. Furthermore, if the relay terminal determines that the network it accesses does not support emergency services, the relay terminal does not need to send a first discovery message to the remote terminal, or the relay terminal sends a first discovery message to the remote terminal, but the first discovery message does not carry an RSC corresponding to emergency services.

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

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

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

[0231] In some other embodiments of this application, the relay terminal may further determine whether the network authorizes a remote terminal to access emergency services, thereby preventing unauthorized remote terminal access to emergency services. In this application, “accessing emergency services” may be replaced by alternatives such as “using emergency services” or “acquire emergency services.”

[0232] In a possible implementation, during the procedure for establishing a connection to a remote terminal, the relay terminal determines whether the network authorizes the remote terminal to access emergency services.

[0233] In this case, method 400 further includes: The remote terminal sends a third message to the relay terminal, and in response, the relay terminal receives the third message from the remote terminal, which is used to request the establishment of a connection to the relay terminal, which is used for the transmission of emergency services. After receiving the third message, the relay terminal sends a second message to the AMF, and in response, the AMF receives the second message from the relay terminal, which is used to request authorization for the remote terminal to access emergency services. After receiving the second message, the AMF sends an authorization result to the relay terminal, and in response, the relay terminal receives the authorization result from the AMF. If the authorization result indicates that the remote terminal has been successfully authorized to access emergency services, the relay terminal sends a fifth message to the remote terminal, and in response, the remote terminal receives the fifth message from the relay terminal, which includes information indicating that the connection has been successfully established. Alternatively, if the authorization result indicates that the remote terminal failed to authorize access to the emergency service, the relay terminal sends a sixth message to the remote terminal, and in response, the remote terminal receives a sixth message from the relay terminal, which includes information indicating that the connection could not be established. Optionally, the sixth message may further include a cause value, which is 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, and the sixth message is a direct communication reject message.

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

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

[0237] In one example, method 400 further includes: The remote terminal sends a second discovery message to the relay terminal, and in response, the relay terminal receives a second discovery message from the remote terminal, the second discovery message including an RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal sends a second message to the AMF, and in response, the AMF receives a second message from the relay terminal, 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 an authorization result to the relay terminal, and in response, the relay terminal receives an authorization result from the AMF. Step 401 may specifically include: When the authorization result indicates that the remote terminal has been successfully authorized to access the emergency service, the relay terminal performs step 401.

[0238] Furthermore, if the authorization result indicates that the remote terminal failed to be authorized to access the emergency service, the relay terminal does not need to perform step 401.

[0239] In other words, after receiving the second discovery message from the remote terminal, the relay terminal first determines whether the network authorizes the remote terminal to access emergency services, and if the network successfully authorizes the remote terminal to access emergency services, it further determines whether the network accessed by the relay terminal supports emergency services. The relay terminal then decides whether or not to send a response message to the second discovery message, depending on whether the network accessed by the relay terminal supports emergency services. Obviously, when deciding whether or not to send a response message to the second discovery message, the relay terminal may further consider other factors, such as whether the RSC matches.

[0240] In other examples, method 400 further includes: The remote terminal sends a second discovery message to the relay terminal, and in response, the relay terminal receives a second discovery message from the remote terminal, the second discovery message containing an RSC corresponding to emergency services. After receiving the second discovery message, the relay terminal determines whether the network accessed by the relay terminal supports emergency services. If the network accessed by the relay terminal supports emergency services, the relay terminal sends a second message to the AMF, and in response, the AMF receives a second message from the relay terminal, the second message used to request authorization for the remote terminal to access emergency services. After receiving the second message, the AMF sends an authorization result to the relay terminal, and in response, the relay terminal receives an authorization result from the AMF. Step 402 may specifically include: When the authorization result indicates that the remote terminal has been successfully authorized to access emergency services, the relay terminal sends a response message to the second discovery message to the remote terminal. Furthermore, if the authorization result indicates that the remote terminal failed to authorize access to the emergency service, the relay terminal does not need to send a response message to the remote terminal for the second discovery message. Obviously, when deciding whether or not to send a response message for the second discovery message, the relay terminal may further consider other factors, such as whether the RSC matches.

[0241] Furthermore, if the network accessed by the relay terminal does not support emergency services, the relay terminal does not need to send a 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, and if the network accessed by the relay terminal supports emergency services, it further determines whether the network authorizes the remote terminal to access emergency services. The relay terminal then either sends a response message to the second discovery message or not, depending on whether the network authorizes the remote terminal to access emergency services.

[0243] In yet another example, method 400 further includes: The remote terminal sends a second discovery message to the relay terminal, and in response, the relay terminal receives a second discovery message from the remote terminal, the second discovery message including an RSC corresponding to emergency services. 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 used to request authorization for the remote terminal to access emergency services. After receiving the second message, the AMF sends an authorization result to the relay terminal, and in response, the relay terminal receives an authorization result from the AMF. Step 402 may specifically include: If the network accessed by the relay terminal supports emergency services and the authorization result indicates that the remote terminal has been successfully authorized to access emergency services, the relay terminal sends a response message to the second discovery message to the remote terminal. Obviously, when deciding whether or not to send a response message to the second discovery message, the relay terminal may further consider other factors, such as whether or not the RSCs match.

[0244] Furthermore, if the network accessed by the relay terminal does not support emergency services, and / or if the authorization result indicates that the remote terminal failed to be authorized to access emergency services, the relay terminal does not need to send a response message to the remote terminal for the second discovery message.

[0245] In other words, after receiving the second discovery message from the remote terminal, the relay terminal determines whether the network accessed by the relay terminal supports emergency services and whether the network authorizes the remote terminal to access emergency services. The relay terminal then 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 decides whether or not to send a response message to the second discovery message.

[0246] Optionally, Method 400 further includes: The AMF obtains an authorization result before transmitting the authorization result to the relay terminal, and the authorization result indicates whether the remote terminal was successfully authorized to access the emergency service or failed to be authorized to access the emergency service.

[0247] In a possible implementation, the AMF obtains authorization results from the authorization network element. Specifically, the AMF sends a fourth message to the authorization network element, and in response, the authorization network element receives the fourth message from the AMF, which 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 in response, the AMF receives the authorization result from the authorization network element.

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

[0249] Optionally, method 400 further includes: the remote terminal sends a seventh message to the relay terminal, the relay terminal receives the seventh message from the remote terminal, the seventh message is used to request the relay terminal to establish a connection, the connection is used for the transmission of emergency services. If the relay terminal does not have an emergency PDU session after receiving the seventh message, the relay terminal requests to establish an emergency PDU session, or if the relay terminal has an emergency PDU session, the relay terminal does 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 and third messages may be the same message or different messages. This is not limited to these two.

[0252] In some other embodiments of this application, Method 400 may further include: The PCF obtains a relay service code corresponding to an emergency service; the PCF transmits first configuration information to a relay terminal, to which the relay terminal receives first configuration information from the PCF, the first configuration information including a relay service code corresponding to an emergency service, and / or the PCF transmits second configuration information to a remote terminal, to which the remote terminal receives second configuration information from the PCF, the second configuration information including a relay service code corresponding to an emergency service. In other words, the PCF configures a relay service code corresponding to an emergency service for the relay terminal and / or the remote terminal. It should be noted that the step here merely indicates that the PCF configures a relay service code corresponding to an emergency service for the relay terminal and the remote terminal. The PCF configuring a relay service code corresponding to an emergency service for the relay terminal and the PCF configuring a relay service code corresponding to an emergency service for the relay terminal and the remote terminal are independent processes. In the configuration process, the PCF does not consider whether a connection will subsequently be established between the relay terminal and the remote terminal.

[0253] Optionally, PCF obtaining relay service codes for emergency services includes: PCF obtaining relay service codes for emergency services locally or from AF. Local relay service codes for emergency services within PCF may be pre-configured or pre-defined.

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

[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 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. The use of the connection for the transmission of the emergency service may be understood as the RSC included in the context of the connection corresponding to the emergency service. The connection may be understood as a PC5 connection.

[0256] For example, the PCF configures multiple RSCs, including an RSC for emergency services, and the respective priorities of the multiple RSCs, by using first configuration information for a relay terminal. The relay terminal establishes multiple connections to remote terminals, and the multiple connections have a one-to-one correspondence with the multiple RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the relay terminal releases some of its established connections, for example, when the relay terminal's transmission resources or capacity are limited, the relay terminal may release connections with lower priority RSCs from among the multiple 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 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. The use of the connection for the transmission of the emergency service may be understood as the RSC included in the context of the connection corresponding to the emergency service. The connection may be understood as a PC5 connection.

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

[0259] In some other embodiments of this application, Method 400 further includes: The relay terminal transmits a first information to the AMF, and in response, the AMF receives the first information from the relay terminal, the first information indicating that the relay terminal's relay service is used for emergency services (relay service for emergency services), or the first information indicating that the relay terminal provides emergency services to a remote terminal. In other words, the relay terminal reports to the AMF that it is in a state where it is providing relay services for emergency services, or that it is providing emergency services to a remote terminal, so that the AMF does not restrict the relay terminal with respect to access control or mobility control. For example, the relay terminal may provide relay services for emergency services in a non-allowed area. Similarly, the emergency services here may be a general type of service, or a specific emergency service.

[0260] Optionally, after the AMF receives the first piece of information, it stores that information in the relay terminal's context.

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

[0262] Optionally, when the PDU session establishment message carries first information, the first information indicates that the PDU session will be used for emergency service transmission. In this case, the AMF may, based on the first information, select an SMF that can provide emergency service, or the AMF may send the first information to the SMF. When the AMF sends the first information to the SMF, the SMF, based on the first information, learns that the PDU session will be used for emergency service transmission and then selects a UPF that can provide emergency service.

[0263] In some other embodiments of this application, Method 400 further includes: a relay terminal transmits a second information to the AMF, and in response, the AMF receives the second information from the relay terminal, the second information indicating that the relay terminal is withdrawn from providing emergency services to a remote terminal, or the second information indicating that the relay terminal will not provide emergency services to a remote terminal. In other words, the relay terminal reports to the AMF that it is not in a state to provide relay services for emergency services, or that it will not provide emergency services to a remote terminal, causing the AMF to restrict the relay terminal with respect to access control or mobility control.

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

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

[0266] It should be noted that in Method 400, the phrase "the network accessed by the relay terminal supports emergency services" can be replaced with "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, if the network accessed by the relay terminal supports emergency services, provide the relay terminal with an RSC corresponding to the emergency service. A detailed description is provided below with reference to Figure 5.

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

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

[0270] For explanations of "the network supports emergency services" and "emergency services," see Step 401. Further details will not be provided here.

[0271] This application describes many methods by which the PCF determines whether a network accessed by a relay terminal supports emergency services. These methods are not limited to the above.

[0272] In possible implementations, the PCF determines that the network accessed by the relay terminal supports emergency services if at least one of the following conditions is met: the PCF has received an emergency service support indicator from the AMF, or the PCF has stored or preconfigured an emergency service support indicator. In other possible implementations, the PCF determines that the network accessed by the relay terminal does not support emergency services if none of the following conditions are met: the PCF has received an emergency service support indicator from the AMF, or the PCF has stored or preconfigured an 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 indicators stored or pre-configured in the PCF are network capability information.

[0275] Optionally, network capability information may be derived from operation, administration, and maintenance (OAM) network elements.

[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] In response, the relay terminal receives the first configuration information from the PCF.

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

[0279] For a description of "RSCs responding to emergency services," see Step 402. Further details will not be provided here.

[0280] Optionally, method 500 further includes: The PCF obtains a relay service code corresponding to an emergency service. In possible implementations, the PCF obtaining a relay service code corresponding to an emergency service includes: The PCF obtains a relay service code corresponding to an emergency service locally or from an AF. Local relay service codes corresponding to emergency services within the PCF may be preconfigured or predefined.

[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, inter-PLMN relay services 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 for emergency services to the remote terminal).

[0282] In other words, the PCF configures a relay service code for the relay terminal that corresponds to emergency services only when the network accessed by the relay terminal supports emergency services, and as a result, the relay terminal participates in the relay discovery procedure for emergency services.

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

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

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

[0286] In a possible implementation, the first message is the first discovery message, and the first discovery message includes an RSC corresponding to an 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 relevant description in FIG. 3. Details are not described again here.

[0287] In another possible implementation, the first message is a response message, and the response message is used to respond to the second discovery message from the remote terminal. The second discovery message includes a relay service code corresponding to an emergency service. For example, when the remote terminal and the relay terminal use the 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 are not 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 the emergency registration state is 3 s, and the time when the relay terminal was in the 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 for emergency services supports emergency services, and it is ensured that the relay terminal selected by the remote terminal expecting to access emergency services can provide relay services for emergency services. 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 emergency services, so as to avoid the access of un-authorized remote terminals to emergency services.

[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 emergency services.

[0297] In this case, method 500 further includes: The remote terminal sends a third message to the relay terminal, and in response, the relay terminal receives the third message from the remote terminal, which is used to request the establishment of a connection to the relay terminal, which is used for the transmission of emergency services. After receiving the third message, the relay terminal sends a second message to the AMF, and in response, the AMF receives the second message from the relay terminal, which is used to request authorization for the remote terminal to access emergency services. After receiving the second message, the AMF sends an authorization result to the relay terminal, and in response, the relay terminal receives the authorization result from the AMF. If the authorization result indicates that the remote terminal has been successfully authorized to access emergency services, the relay terminal sends a fifth message to the remote terminal, and in response, the remote terminal receives the fifth message from the relay terminal, which includes information indicating that the connection has been successfully established. Alternatively, if the authorization result indicates that the remote terminal failed to authorize access to the emergency service, the relay terminal sends a sixth message to the remote terminal, and in response, the remote terminal receives a sixth message from the relay terminal, which includes information indicating that the connection could not be established. Optionally, the sixth message may further include a cause value, which is 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 and fourth messages are authorization request messages, and the authorization result is carried in the authorization response message.

[0300] In other possible implementations, in a relay discovery procedure (e.g., a relay discovery procedure using Model B), the relay terminal determines whether the network authorizes the remote terminal to access emergency services.

[0301] In this case, method 500 further includes: The remote terminal sends a second discovery message to the relay terminal, and in response, the relay terminal receives a second discovery message from the remote terminal, the second discovery message including an RSC corresponding to the emergency service. After receiving the second discovery message, the relay terminal sends a second message to the AMF, and in response, the AMF receives a second message from the relay terminal, the second message used to request authorization for the remote terminal to access the emergency service. After receiving the second message, the AMF sends an authorization result to the relay terminal, and in response, the relay terminal receives an authorization result from the AMF. Step 503 may specifically include: When the authorization result indicates that the remote terminal has been successfully authorized to access the emergency service, the relay terminal sends a response message to the second discovery message to the remote terminal. Obviously, when deciding whether or not to send a response message to the second discovery message, the relay terminal may further consider other factors, such as whether or not the RSCs match.

[0302] Furthermore, if the authorization result indicates that the remote terminal failed to be authorized to access the emergency service, the relay terminal does not need to send a response message to the remote terminal for the second discovery message.

[0303] Optionally, method 500 further includes: The AMF obtains an authorization result before transmitting the authorization result to the relay terminal, the authorization result indicating whether the remote terminal was successfully authorized to access the emergency service or failed to be authorized to access the emergency service.

[0304] In a possible implementation, the AMF obtains authorization results from the authorization network element. Specifically, the AMF sends a fourth message to the authorization network element, and in response, the authorization network element receives the fourth message from the AMF, which 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 in response, the AMF receives the authorization result from the authorization network element.

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

[0306] Optionally, method 500 further includes: the remote terminal sends a seventh message to the relay terminal, the relay terminal receives the seventh message from the remote terminal, the seventh message is used to request the relay terminal to establish a connection, the connection is used for the transmission of emergency services. If the relay terminal does not have an emergency PDU session after receiving the seventh message, the relay terminal requests to establish an emergency PDU session, or if the relay terminal has an emergency PDU session, the relay terminal does not have 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 and third messages may be the same message or different messages. This is not limited to these two.

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

[0310] For example, the PCF configures multiple RSCs, including an RSC for emergency services, and the respective priorities of the multiple RSCs, by using first configuration information for a relay terminal. The relay terminal establishes multiple connections to remote terminals, and the multiple connections have a one-to-one correspondence with the multiple RSCs (for example, connection 1 corresponds to RSC1 (the context of connection 1 includes RSC1), connection 2 corresponds to RSC2 (the context of connection 2 includes RSC2)). When the relay terminal releases some of its established connections, for example, when the relay terminal's transmission resources or capacity are limited, the relay terminal may release connections with lower priority RSCs from among the multiple established connections.

[0311] In some other embodiments of this application, Method 500 further includes: the PCF transmits second configuration information to a remote terminal, and in response, the remote terminal receives second configuration information from the PCF, the second configuration information includes a relay service code corresponding to an 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 the RSC included in the context of the connection corresponding 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 relay terminal transmits a first information to the AMF, and in response, the AMF receives the first information from the relay terminal, the first information indicating that the relay terminal's relay service is used for emergency services, or the first information indicating that the relay terminal provides emergency services to a remote terminal. In other words, the relay terminal reports to the AMF that it is in a state where it is providing relay services for emergency services, or that it is providing emergency services to a remote terminal, so that the AMF does not restrict the relay terminal with respect to access control or mobility control. For example, the relay terminal may provide relay services for emergency services in a non-allowed area. The emergency services here may be a general type of service, or a specific type of emergency service.

[0315] Optionally, after the AMF receives the first piece of information, it stores that information in the relay terminal's context.

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

[0317] Optionally, when the PDU session establishment message carries first information, the first information indicates that the PDU session will be used for emergency service transmission. In this case, the AMF may, based on the first information, select an SMF that can provide emergency service, or the AMF may send the first information to the SMF. When the AMF sends the first information to the SMF, the SMF, based on the first information, learns that the PDU session will be used for emergency service transmission and then selects a UPF that can provide emergency service.

[0318] In some other embodiments of this application, Method 500 further includes: a relay terminal transmits a second information to the AMF, and in response, the AMF receives the second information from the relay terminal, the second information indicating that the relay terminal is withdrawn from providing emergency services to a remote terminal, or the second information indicating that the relay terminal will not provide emergency services to a remote terminal. In other words, the relay terminal reports to the AMF that it is not in a state to provide relay services for emergency services, or that it will not provide emergency services to a remote terminal, causing the AMF to restrict the relay terminal with respect to access control or mobility control.

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

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

[0321] It should be noted that in Method 500, the phrase "the network accessed by the relay terminal supports emergency services" can be replaced with "the network supports emergency services."

[0322] The technical solutions in this application will be described below with reference to specific examples.

[0323] Example 1

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

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

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

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

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

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

[0330] Step 601 is an optional step, and it should be noted that the PCF may, as an alternative, obtain an RSC corresponding to emergency services in another manner. For example, the RSC corresponding to emergency services within the PCF may be predefined or preconfigured.

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

[0332] Optionally, PCF may provide remote terminals with different RSC priorities, so that when resources are limited, the remote terminal will preferentially release PC5 connections corresponding to RSCs with lower priority.

[0333] A PC5 connection corresponding to an RSC may, alternatively, be understood as a PC5 connection identified by an RSC.

[0334] Here, "different RSCs" refers to RSCs provided to remote terminals by PCF, and may include RSCs corresponding to normal services and / or RSCs corresponding to emergency services.

[0335] In a possible implementation, as shown in Figure 6, when a UE policy is provided to a remote terminal, the PCF provides an RSC corresponding to the emergency service to the remote terminal, and the RSC corresponding to the emergency service is transported in a UE policy container.

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

[0337] Optionally, the PCF may further provide relay terminals with different RSC priorities, so that when resources are limited, the relay terminals will preferentially release PC5 connections corresponding to RSCs with lower priority.

[0338] Here, "different RSCs" refers to RSCs provided to relay terminals by the PCF, and may include RSCs corresponding to normal services and / or RSCs corresponding to emergency services.

[0339] In a possible implementation, as shown in Figure 6, when a UE policy is provided to a relay terminal, the PCF provides the relay terminal with an RSC corresponding to the emergency service, and the RSC corresponding to the emergency service is transported in a UE policy container.

[0340] Step 604: The network notifies relay terminals that the network is supporting emergency services.

[0341] In possible implementations, 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 emergency services. For example, the AMF sends the Emergency Service Support Indicator to the relay terminal during the relay terminal registration process. For instance, the AMF includes the Emergency Service Support Indicator in the registration accept message.

[0342] In possible implementations, a RAN device sends an emergency service support indicator to a relay terminal. This indicator indicates that the network accessed by the relay terminal supports emergency services. For example, an access network device sends the emergency service support indicator to the relay terminal during the relay terminal's network access process. For instance, the access network device includes the emergency service support indicator in an RRC (radio resource control configuration message). In another example, the access network device sends the emergency service support indicator in a broadcast message, and the relay terminal receives the indicator included in the broadcast message.

[0343] Thus, when a relay terminal receives an emergency service support instruction, this means that the relay terminal can establish an emergency PDU session to obtain emergency services. Here, “emergency PDU session” may be understood as a PDU session used for transmitting emergency services, or as a PDU session corresponding to an emergency DNN.

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

[0345] Next, the remote terminal and the relay terminal may perform a relay discovery procedure. In method 600, there may also be two types of relay discovery procedures, namely Model A and Model B. When the relay discovery procedure using Model A is used, the following steps 605 and 606 are performed. When the relay discovery procedure using Model B is used, the following steps 607 to 609 are performed.

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

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

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

[0349] Accordingly, the remote terminal listens for and receives discovery messages.

[0350] The discovery message carries an RSC (Report Service Center) to respond to emergency services. The discovery message may correspond to the first discovery message described above.

[0351] Optionally, if 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, if the relay terminal is in a non-emergency registration state, the discovery message does not carry an emergency registration indicator and / or emergency registration time information.

[0352] The emergency registration indicator shows that a relay terminal is in an emergency registration state. During the registration process, the terminal includes the registration type in the registration request message, and emergency registration is one of the registration types. Therefore, a relay terminal being in an emergency registration state can be understood as the relay terminal being in the emergency registration process.

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

[0354] Step 607: If the remote terminal receives an emergency service, the remote terminal proactively sends a discovery message (e.g., a solicitation message).

[0355] Accordingly, the relay terminal listens for and receives discovery messages.

[0356] The discovery message carries an RSC (Report Service Center) to respond to emergency services. The discovery message may also correspond to the second discovery message mentioned above.

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

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

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

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

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

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

[0363] Optionally, if 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, if the relay terminal is in a non-emergency registration state, the response message does not carry an emergency registration indicator and / or emergency registration time information. See step 606 for a description of the emergency registration indicator and emergency registration time information. Further details are not provided 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 from one or more relay terminals that send the discovery message whose RSC matches the expected RSC, 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 relay terminals based on the emergency registration indicator and / or emergency registration time information carried in the discovery or response message. For example, the remote terminal preferentially selects relay terminals that are in a non-emergency registration state. In another example, if all relay terminals sending the discovery or response message are in an emergency registration state, the remote terminal preferentially selects relay terminals with a longer remaining time in the emergency registration state.

[0367] In Example 1, when the network accessed by the relay terminal supports emergency services, the relay terminal's participation in the emergency service relay discovery procedure includes sending an RSC corresponding to the emergency service in the discovery message, or responding to a discovery message that carries an RSC corresponding to the emergency service. This helps to avoid situations where the relay terminal discovered by the remote terminal does not support emergency services.

[0368] Example 2

[0369] In Example 2, the PCF decides to provide the relay terminal with an RSC that supports emergency services, based on the fact that the network accessed by the relay terminal supports emergency services, and as a result, the relay terminal participates in the relay discovery procedure that supports emergency services.

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

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

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

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

[0374] The implementation methods for steps 701 and 702 are the same as those for steps 601 and 602. References to the explanations for steps 601 and 602 may be made. Further details will not be explained again here.

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

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

[0377] Step 704: After receiving the registration request message, the AMF retrieves the relay terminal's subscription information from the UDM.

[0378] The subscription information includes information indicating whether or not 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, the AMF sends an emergency service support indicator to the PCF during the 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, the PCF determines, based on the emergency service support indicator in step 705, that the network accessed by the relay terminal supports emergency services.

[0385] In other possible implementations, the PCF determines, based on locally pre-configured network capability information, 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 an RSC corresponding to the emergency services.

[0387] Optionally, the PCF may further provide relay terminals with different RSC priorities, so that when resources are limited, the relay terminals will preferentially release PC5 connections corresponding to RSCs with lower priority.

[0388] Here, "different RSCs" refers to RSCs provided to relay terminals by the PCF, and may include RSCs corresponding to normal services and / or RSCs corresponding to emergency services.

[0389] In a possible implementation, as shown in Figure 7, when a UE policy is provided to a relay terminal, the PCF provides the relay terminal with an RSC corresponding to the emergency service, and the RSC corresponding to the emergency service is transported in the UE policy container.

[0390] Next, the remote terminal and the relay terminal may perform a relay discovery procedure. In method 700, there may also be two types of relay discovery procedures, namely Model A and Model B. If the relay discovery procedure using Model A is used, the following step 708 is performed. If the relay discovery procedure using Model B is used, the following steps 709 and 710 are performed.

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

[0392] Accordingly, the remote terminal listens for and receives discovery messages.

[0393] The discovery message carries an RSC (Report Service Center) to respond to emergency services. The discovery message may correspond to the first discovery message described above.

[0394] Optionally, if 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, if the relay terminal is in a non-emergency registration state, the discovery message does not carry an emergency registration indicator and / or emergency registration time information.

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

[0396] The emergency registration time information indicates at least one of the following: the time the relay terminal is in the emergency registration state, the remaining time (left time) the relay terminal is in the emergency registration state, or the time the relay terminal was in the emergency registration state. When a relay terminal performs emergency registration, the AMF assigns a periodic registration refresh timer to the relay terminal. The periodic registration refresh timer is the maximum remaining time. After the periodic registration refresh timer expires, the relay terminal enters the unregistered state.

[0397] Step 709: If the remote terminal receives an emergency service, the remote terminal proactively sends a discovery message (e.g., a solicitation message).

[0398] Accordingly, the relay terminal listens for and receives discovery messages.

[0399] The discovery message carries an RSC (Report Service Center) to respond to emergency services. The discovery message may also correspond to the second discovery message mentioned above.

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

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

[0402] Optionally, if 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, if the relay terminal is in a non-emergency registration state, the response message does not carry an emergency registration indicator and / or emergency registration time information. See step 708 for a description of the emergency registration indicator and emergency registration time information. Further details are not provided here.

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

[0404] The implementation method for step 711 is the same as that for step 610. Referencing the explanation for step 610 may be provided. Further details will not be explained again here.

[0405] In Example 2, when the network accessed by the relay terminal supports emergency services, the PCF decides to provide the relay terminal with an RSC corresponding to emergency services. When the network accessed by the relay terminal does not support emergency services, the PCF does not provide the relay terminal with an RSC corresponding to emergency services. Therefore, the relay terminal does not participate in relay discovery procedures that support emergency services. This helps to avoid situations where a relay terminal discovered by a remote terminal does not support emergency services. Furthermore, the method shown in Example 2 simplifies the relay terminal determination logic.

[0406] Example 3

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

[0408] The steps in method 800 may be performed after the remote terminal has selected the relay terminal. For example, as shown in Figure 8, the steps in method 800 may be performed after the procedure in Example 1 or Example 2.

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

[0410] In response, the relay terminal receives communication request messages directly from the remote terminal.

[0411] A direct communication request message includes the remote terminal identifier and RSC. The remote terminal identifier includes at least one of the following: the remote terminal's subscription permanent identifier (SUPI), subscription concealed identifier (SUCI), generic public subscription identifier (GPSI), permanent equipment identifier (PEI), or mobile subscriber international ISDN / PSTN number (MSISDN), or application layer identifier (e.g., user information, user info). ISDN is the Integrated Service Digital Network, and PSTN is the Public Switched Telephone Network. MSISDN may be understood as identifying information that the terminal can disclose externally, such as the terminal's telephone number. The RSC here is the RSC corresponding to emergency services.

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

[0413] In response, the AMF receives an authorization request message from the relay terminal.

[0414] The authorization request message here may also be a NAS message. The authorization request message includes the remote terminal identifier and RSC. The authorization request message is used to request authorization for the remote terminal to access the service corresponding to the RSC. If authorization is successful, this indicates that the remote terminal can access the service corresponding to the RSC; if authorization fails, 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, if the RSC in the direct communication request message is determined to correspond to an emergency service, the relay terminal sends an authorization request message to the AMF requesting authorization for the remote terminal to access the service corresponding to the RSC.

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

[0417] In response, the authorization network element receives an authorization request message from the AMF.

[0418] The authorization request message here includes the remote terminal identifier and 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 AMF.

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

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

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

[0422] The authorization response message includes the authorization result. The authorization result may be either successful or unsuccessful. If the authorization result is successful, it indicates that the remote terminal can access the RSC-corresponding service; if the authorization result is unsuccessful, it indicates that the remote terminal cannot access the RSC-corresponding service.

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

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

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

[0426] The authorization response message includes the authorization result. The authorization result may be either successful or unsuccessful. If the authorization result is successful, it indicates that the remote terminal can access the RSC-corresponding service; if the authorization result is unsuccessful, it indicates that the remote terminal cannot access the RSC-corresponding service.

[0427] Step 806: The relay terminal decides whether or not to establish a PC5 connection to the remote terminal based on the authorization result.

[0428] Specifically, if the authorization result is successful, the relay terminal decides to establish a PC5 connection to the remote terminal. If the authorization result is unsuccessful, the relay terminal decides not to establish a PC5 connection to the remote terminal.

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

[0430] Accordingly, the remote terminal receives a communication acceptance message directly from the relay terminal.

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

[0432] In response, the remote terminal receives a communication rejection message directly from the relay terminal.

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

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

[0435] Step 809: The relay terminal transmits the first piece of information to the AMF.

[0436] In response, the AMF receives the first piece of information from the relay terminal.

[0437] The first piece of information indicates that the relay terminal's relay service is being used for emergency services. That is, the relay terminal notifies the network that it is processing, performing, or relaying emergency services.

[0438] Optionally, the first information may be delivered 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. Obviously, 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 opportunities for performing step 809 are not limited in this application.

[0441] For example, the relay terminal performs step 809 in an authorization procedure that authorizes the remote terminal to access emergency services (for example, as shown in Figure 8, step 809 may be performed after step 802).

[0442] In another example, the relay terminal starts step 809 after performing step 801.

[0443] In another example, the relay terminal starts step 809 after performing step 806.

[0444] In another example, the relay terminal starts step 809 after receiving a discovery message (Model B) from the remote terminal.

[0445] In another example, the relay terminal receives a discovery message (Model B) from the remote terminal and, after determining that the network accessed by the relay terminal supports emergency services, initiates step 809.

[0446] In another example, the relay terminal initiates step 809 after sending a discovery message (Model A).

[0447] In Example 3, the relay terminal establishes a PC5 connection to the remote terminal only after it has determined that the remote terminal is authorized to access emergency services, thereby providing the remote terminal with relay services for emergency services. This helps prevent unauthorized remote terminals from accessing emergency services.

[0448] The method provided in this application is described in detail above with reference to Figures 4 to 8. Embodiments of the apparatus of this application are described in detail below with reference to Figures 9 and 10.

[0449] To realize the functions in the embodiments described above, it can be understood that the apparatus in Figure 9 or Figure 10 includes corresponding hardware structures and / or software modules for performing each function. Those skilled in the art will readily recognize that, in this application, the units and steps of the methods in the examples described with reference to the embodiments disclosed herein may be implemented by hardware or by a combination of hardware and computer software. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application scenario and design constraints of the technical solution.

[0450] Figures 9 and 10 illustrate the structure of a possible device according to an embodiment of this application. The device may be configured to implement the functions of a relay terminal, a policy control function network element, a remote terminal, or an application function network element in the embodiment of the method described above, and thus may also implement the beneficial effects of the embodiment of the method described above.

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

[0452] In some implementations, when the device 900 is configured to implement the functions of a relay terminal in an embodiment of the above method, the processing unit 920 is configured to determine that the network accessed by the relay terminal supports emergency services. The transceiver unit 910 is configured to transmit a first message, which is used by a remote terminal to discover the relay terminal.

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

[0454] Optionally, the processing unit 920 is specifically configured to determine that the network accessed by the relay terminal supports emergency services when at least one of the following conditions is met: the relay terminal has received an emergency service support indicator from an access and mobility management function network element or access network device; the relay terminal has stored an emergency service support indicator; or 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 emergency services.

[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 indicating that the relay terminal is in an emergency registration state, and the emergency registration time information indicating the time or remaining time the relay terminal has been 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 the priority of relay service codes corresponding to emergency services, and the processing unit 920 is further configured to maintain or release connections between relay terminals and remote terminals based on priority, and the connections are used for the transmission of emergency services.

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

[0460] Optionally, the transceiver unit 910 is further configured to receive a second discovery message from a 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 is 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 been authorized to access emergency services.

[0461] Optionally, before it is determined 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 it is determined that the network accessed by the relay terminal supports emergency services, the transceiver unit 910 is further configured to send a second message to the access and mobility management network element, which is used to request authorization for the remote terminal to access emergency services, and is further configured to receive an authorization result from the access and mobility management network element. Specifically, the transceiver unit 910 is configured to send a response message to the remote terminal when the authorization result indicates that the remote terminal has been successfully authorized 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 terminal's relay service is to be used for emergency services.

[0463] In some other implementations, when the device 900 is configured to implement the functions of a relay terminal in the embodiment of the above method, the processing unit 920 is configured to generate a first message in which 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 indicating that the relay terminal is in an emergency registration state, and the emergency registration time information indicating the time or remaining time that the relay terminal has been in an emergency registration state. The transceiver unit 910 is configured to transmit the first message, which is used by a remote terminal to discover the relay terminal.

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

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

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

[0468] Optionally, the transceiver unit 910 is further configured to receive a second discovery message from a 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 to receive an authorization result from the access and mobility management function network element. Specifically, the transceiver unit 910 is configured to transmit a response message to the remote terminal when the authorization result indicates that the remote terminal has been successfully authorized to access emergency services.

[0469] 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 terminal's relay service is to be used for emergency services.

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

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

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

[0473] Optionally, the processing unit 920 may be further configured to determine that a network accessed by a relay terminal supports emergency services when at least one of the following conditions is met: 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 has stored or pre-configured an emergency service support indicator.

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

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

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

[0477] Optionally, the transceiver unit 910 is specifically configured to obtain relay service codes corresponding to emergency services from application function network elements.

[0478] When the device 900 is configured to implement the functions of a remote terminal in the embodiment of the above method, 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 an 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, which includes a relay service code corresponding to an emergency service, or the first message is a response message, which is used to respond to a second discovery message sent by a remote terminal, which includes a relay service code corresponding to an emergency service.

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

[0481] Optionally, the second configuration information further includes the priority of relay service codes corresponding to 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 relay service codes corresponding to emergency services, and the connection is used for the transmission of emergency services.

[0482] When the device 900 is configured to implement the AF functions in the embodiment of the above method, 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 descriptions in the embodiments of the method described above. Further details will not be provided here.

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

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

[0486] Optionally, the device 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 device 1000 is configured to implement the above method, the processor 1010 is configured to execute instructions to implement the functions of the processing unit 920, and the interface circuit 1020 is configured to implement the functions of the transceiver unit 910.

[0487] For example, when device 1000 is a chip used in a relay terminal, the chip implements the functions of the relay terminal in the embodiment of the above method. The chip receives information from other modules in the relay terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the relay terminal by the other device, or the chip transmits information to other modules in the relay terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the other device by the relay terminal.

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

[0489] For example, when device 1000 is a chip used in a remote terminal, the chip implements the functions of the remote terminal in the embodiment of the above method. The chip receives information from other modules in the remote terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the remote terminal by the other device, or the chip transmits information to other modules in the remote terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the other device by the remote terminal.

[0490] For example, when device 1000 is a chip used in an application function network element, the chip implements the functions of the application function network element in the embodiment of the above method. The chip receives information from other modules in the application function network element (e.g., a radio frequency module or an antenna), and the information is transmitted to the application function network element by the other device, or the chip transmits information to other modules in the application function network element (e.g., a radio frequency module or an antenna), and the information is transmitted to the other device by the application function network element.

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

[0492] This application further provides a computer-readable storage medium that stores computer instructions for implementing a method performed by a relay terminal, a policy control function network element, a remote terminal, or an application function network element in an embodiment of the above method.

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

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

[0495] For a description of the relevant aspects and beneficial effects of any one of the devices provided above, please refer to the corresponding embodiments of the methods provided above. Further details will not be described again here.

[0496] The processor in the embodiments of this application may be a central processing unit (CPU), or it may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or another programmable logic device, a transistor logic device, a hardware component, 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 random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, removable hard disks, compact disc read-only memory (CD-ROM), or any other form of storage medium known in the art. For example, the storage medium may be coupled to a 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 storage medium may reside in an ASIC. Furthermore, the ASIC may reside in a relay terminal, a policy control function network element, a remote terminal, or an application function network element. Obviously, the processor and storage medium may, alternatively, reside 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 embodiments described above may be implemented by software, hardware, firmware, or a 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. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded into a computer and executed, 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, user equipment, or other programmable device. The computer program or instruction may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instruction may be transmitted by wired or wireless means from one 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 that integrates one or more available media, such as a server or data center. The usable media may be magnetic media, such as floppy disks, hard disks, or magnetic tapes; optical media, such as digital video discs; or semiconductor media, such as solid-state drives.

[0499] In the embodiments of this application, unless otherwise specified or unless there is a logical contradiction, the terminology and / or descriptions in different embodiments are consistent and may be referenced to one another, and the technical features in different embodiments may be combined on the basis of 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 the purpose of facilitating explanation and are not used to limit the scope of the embodiments of this application. The sequence numbers of the processes described above do not imply an execution order, and the execution order of the processes should be determined based on the function and internal logic of the processes.

[0501] Unless otherwise specified, the meaning of all technical and scientific terms used in the embodiments of this application is the same as that ordinarily understood by a person skilled in the art. The terms used in this application are intended solely to illustrate specific embodiments and not to limit the scope of this application. The above are illustrative examples, and it should be understood that these examples are intended solely to help a person skilled in the art understand the embodiments of this application and not to limit the embodiments of this application to specific values ​​or examples of specific scenarios. It will be apparent that a person skilled in the art can make various equivalent modifications or variations based on the above examples, and such modifications and variations also fall within the scope of the embodiments of this application.

[0502] The above description merely outlines a specific mode of implementation of this application and is not intended to limit the scope of protection of this application. Any modification or substitution that is readily conceivable to a person skilled in the art within the scope of the technical scope disclosed in this application shall fall within the scope of protection of this application. Accordingly, the scope of protection of this application shall be subject to the scope of protection of the claims.

Claims

1. A method of communication, The relay terminal determines that the network accessed by the relay terminal supports emergency services, The steps include: the relay terminal transmits a first message, the first message being used by a remote terminal to discover the relay terminal; and Includes, 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. A method wherein 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 that the relay terminal has been in the emergency registration state.

2. The step of a relay terminal determining that the network accessed by the relay terminal supports emergency services is: The relay terminal, upon receiving an emergency service support indicator from an access and mobility management function network element or access network device, includes the step of determining that the network accessed by the relay terminal supports the emergency service. The method according to claim 1, wherein the emergency service support indicator indicates that the network accessed by the relay terminal supports the emergency service.

3. The method according to claim 1, further comprising the step of receiving the second discovery message by the relay terminal.

4. This method is The method according to any one of claims 1 to 3, further comprising the step of receiving first configuration information from a policy control function network element by the relay terminal, wherein the first configuration information includes the relay service code corresponding to the emergency service.

5. This method is The relay terminal receives a seventh message from the remote terminal, the seventh message is used to request the establishment of a connection to the relay terminal, and the connection is used for the transmission of the emergency service, and the steps are as follows: If, after receiving the seventh message, the relay terminal does not have an emergency protocol data unit (PDU) session for the transmission of the emergency service, the relay terminal requests to establish the emergency PDU session. The method according to any one of claims 1 to 3, further comprising:

6. The method according to claim 5, wherein the seventh message is a direct communication request message.

7. The method is: The policy control function network element obtains the relay service code corresponding to the emergency service, The steps include: transmitting the first configuration information to the relay terminal using the policy control function network element, wherein the first configuration information includes the relay service code corresponding to the emergency service; The method according to claim 4, further comprising:

8. A communication device, A device including at least one processor configured to execute a computer program stored in memory, thereby enabling the device to perform the method described in any one of claims 1 to 3.

9. The apparatus according to claim 8, further comprising a memory.

10. A computer-readable storage medium, A computer-readable storage medium that stores a computer program, and when the computer program is executed on a computer, the computer is able to perform the method according to any one of claims 1 to 3.

11. It is a computer program, The computer program includes instructions that cause a computer to perform the method described in any one of claims 1 to 3.

12. A communication system including a relay terminal and a remote terminal, The relay terminal is configured to perform the method described in any one of claims 1 to 3, The remote terminal is configured to receive the first message, and the system is configured to do so.

13. The communication system further includes a policy control function network element, The aforementioned policy control function network element is Obtain the relay service code corresponding to the aforementioned emergency service, It is configured to transmit first configuration information to the relay terminal, and the first configuration information includes the relay service code corresponding to the emergency service, The system according to claim 12, wherein the relay terminal is configured to receive the first configuration information.

Images