A communication method and apparatus

Abstract

A communication method and device are used to provide a new routing manner of NAS message. In the application, a terminal sends a first uplink NAS message and first information, the first information is used to determine a first target network element, and the first target network element is a network element used for processing the first uplink NAS message. The first uplink NAS message and the first information are received by a first routing network element, the first routing network element can obtain an internal identifier of the first target network element according to the first information, and send the first uplink NAS message to the first target network element according to the internal identifier of the first target network element. After receiving a first downlink NAS message from the first target network element, the first routing network element sends the first downlink NAS message and a temporary identifier of the first target network element to the terminal, and the temporary identifier of the first target network element can be used for routing of a subsequent uplink NAS message.

Description

Technical Field

[0001] This application relates to the field of wireless communication, and more particularly to a communication method and apparatus. Background Technology

[0002] A terminal can establish an N1 connection with an Access and Mobility Management Function (AMF) network element in the core network (CN), and send non-access stratum (NAS) messages to that AMF network element. The AMF network element then determines the routing method based on the type of the NAS message. For example, if the NAS message is of session management type, the AMF network element can route the NAS message to a session management function (SMF) network element; or, if the NAS message is of mobility management type, the AMF network element can determine that the NAS message is addressed to itself and execute the corresponding service logic. In summary, the AMF network element not only needs to route NAS messages but also needs to process its own service logic.

[0003] Currently, discussions are underway to decouple the routing function of AMF network elements, for example, by assigning the routing function to a new network element. How to implement routing of NAS messages by this new network element is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application provides a communication method and apparatus for providing a new routing method for NAS messages.

[0005] In a first aspect, this application provides a communication method and apparatus, which can be executed by a first routing device.

[0006] The first routing device is, for example, the first routing network element or a module (e.g., a chip) in the first routing network element. The first routing network element may also be referred to as the first routing function network element, the first NAS routing network element, the first NAS routing function network element, the first core network portal function (CPF) network element, the first signaling routing function (SRF) network element, etc.

[0007] Taking the execution of this method by the first routing network element as an example, it should be understood that the first routing network element can be replaced by the first routing device. The method includes:

[0008] The first routing network element receives a first uplink NAS message and first information from the terminal. The first information is used to identify the first target network element, which is the network element used to process the first uplink NAS message. The first routing network element then sends the first uplink NAS message to the first target network element based on its internal identifier. After receiving the first downlink NAS message from the first target network element, the first routing network element sends the first downlink NAS message and a temporary identifier of the first target network element to the terminal.

[0009] It should be noted that the first information can be located outside or inside the first uplink NAS message. In both cases, it can be considered that the first routing network element receives both the first uplink NAS message and the first information from the terminal. Furthermore, when the first information is outside the first uplink NAS message, the first uplink NAS message and the first information can be sent through the same message. Alternatively, the first uplink NAS message and the first information can be sent through two separate messages, and the order of these two messages is not limited.

[0010] The temporary identifier of the first target network element can be located outside or inside the first downlink NAS message. In both cases, it can be considered that the first routing network element sends the first downlink NAS message and the temporary identifier of the first target network element to the terminal. Furthermore, when the temporary identifier of the first target network element is located outside the first downlink NAS message, the first downlink NAS message and the temporary identifier of the first target network element can be sent through the same message. Alternatively, the first downlink NAS message and the temporary identifier of the first target network element can be sent through two separate messages, and the order of these two messages is not limited.

[0011] For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0012] In the above technical solution, the first routing network element can receive a first uplink NAS message and first information from the terminal, wherein the first information can be used to determine a first target network element. Therefore, the first routing network element can send / route the first uplink NAS message to the first target network element based on the internal identifier of the first target network element. The first routing network element can also send a temporary identifier of the first target network element to the terminal. This temporary identifier is used for routing subsequent uplink NAS messages (e.g., a second uplink NAS message), thereby enabling the routing network element to route uplink NAS messages.

[0013] The first routing network element is used to route NAS messages. This first routing network element can be a different network element from the AMF network element. Thus, NAS message routing is not limited to being performed by the AMF network element. Compared to existing technologies where NAS messages can only be routed by the AMF network element, this application improves the flexibility of NAS message routing. For example, this application decouples the NAS message routing function from the AMF network element. When the AMF network element introduces new services / features and needs to be restarted, it can avoid affecting the normal routing of NAS messages.

[0014] The first routing network element sends a temporary identifier of the first target network element to the terminal. The temporary identifier of the first target network element can be used for routing subsequent uplink NAS messages (such as the second uplink NAS message). That is, the internal identifier of the first target network element is not exposed to the terminal, and the terminal cannot obtain the actual deployment information of each network element inside the core network, which helps to improve network security.

[0015] In one possible implementation, the first information includes one or more of the following: Extended Protocol Discriminator (EPD), message type, network element (or network function (NF)) type, slice identifier, subnet ID, and protocol data unit (PDU) session identifier. The EPD indicates the NAS type, which may include, for example, session management type or mobility management type.

[0016] For example, the first information is an EPD; or the first information is a combination of an EPD and a service identifier; or the first information is a message type; or the first information is a combination of a message type and a service identifier; or the first information is a combination of an EPD and a message type; or the first information is a combination of an EPD, a message type, and a service identifier. The service identifier includes one or more of the following: network element type, slice identifier, subnet identifier, and PDU session identifier.

[0017] In the above technical solution, the parameter types included in the first information are provided to identify the first target network element that helps meet business needs and improve communication quality. For example, when the first information includes a slice identifier, it can be used to ensure that the discovered first target network element can support specific service requirements (such as low latency and high bandwidth); for example, when the first information includes a subnet identifier, it can be used to limit the network range of the discovered first target network element, which helps optimize the use of network resources and reduce latency.

[0018] In one possible implementation, the first routing network element can also obtain the internal identifier of the first target network element based on the first information. Further, when obtaining the internal identifier of the first target network element, the first routing network element can specifically send a network element discovery request (NF discovery request) to the network repository function (NRF) network element. The NF discovery request includes second information, which is determined based on the first information, and is used to identify the first target network element. The first routing network element receives a discovery request response from the NRF network element, which includes the internal identifier of the first target network element. For example, the first routing network element determines the second information based on the first information.

[0019] In the above technical solution, the first routing network element can request the internal identifier of the first target network element from the NRF network element based on the network element discovery process, and then route the first uplink NAS message to the first target network element.

[0020] In one possible implementation, before sending a network element discovery request to the NRF network element, the first routing network element can determine that the first uplink NAS message does not include the temporary identifier of the first target network element. In one possible example, the first uplink NAS message not including the temporary identifier of the first target network element can specifically mean that the receiver information field in the first uplink NAS message is empty. That is, before sending a network element discovery request to the NRF network element, the first routing network element can determine that the receiver information field in the first uplink NAS message is empty.

[0021] In the above technical solution, the first routing network element can send a network element discovery request to the NRF network element if it determines that the first uplink NAS message does not contain the temporary identifier of the first target network element (for example, if it determines that the receiver information field in the first uplink NAS message is empty). Thus, the first routing network element can request the internal identifier of the first target network element from the NRF network element based on the network element discovery process.

[0022] In one possible implementation, the first routing network element can also obtain a temporary identifier of the first target network element. In one example, the network element discovery response also includes the temporary identifier of the first target network element. That is, the first routing network element can also obtain the temporary identifier of the first target network element from the network element discovery response. For example, the temporary identifier of the first target network element can be generated by the NRF network element after determining the first target network element (or, in other words, the internal identifier of the first target network element). In yet another example, the first routing network element can also generate the temporary identifier of the first target network element.

[0023] In the above technical solution, the first routing network element can also obtain a temporary identifier of the first target network element, which can be used for routing subsequent uplink NAS messages (such as the second uplink NAS message).

[0024] In one possible implementation, the network element discovery request is used to instruct the generation of a temporary identifier for the first target network element. For example, the network element discovery request instructs the NRF network element to generate a temporary identifier for the first target network element. As another example, the NRF network element can not only determine the internal identifier of the first target network element based on the network element discovery request, but also generate a temporary identifier for the first target network element based on the network element discovery request. Exemplarily, the network element discovery request may also carry third information; when the NRF network element determines that the network element discovery request carries third information, it generates a temporary identifier for the first target network element.

[0025] For example, the third information may include one or more of the following: NAS type, NAS message type, indication of generating a temporary identifier for the first target network element, indication of the existence of downlink NAS messages in the network, indication of the existence of other uplink NAS messages in the network, consumer field, and service name field; wherein the consumer field is the identifier of the first routing network element; and the service name field is the service that forwards the NAS message. The third information can be used to instruct the NRF network element to generate a temporary identifier for the first target network element.

[0026] In the above technical solution, the network element discovery request instructs the NRF network element to generate a temporary identifier for the first target network element, so that the first routing network element can obtain the temporary identifier of the first target network element from the network element discovery response. The temporary identifier of the first target network element can be used for routing of subsequent uplink NAS messages (e.g., the second uplink NAS message).

[0027] In one possible implementation, the temporary identifier of the first target network element includes one or more of the following: the identifier of the first routing device (i.e., the first routing network element), information on the first routing device (i.e., the first routing network element) used to uniquely identify the first target network element, the identifier of the NRF network element, and information on the NRF network element used to uniquely identify the first target network element.

[0028] For example, the temporary identifier of the first target network element consists of the identifier of the first routing network element and information on the first routing network element used to uniquely identify the first target network element; or, for another example, the temporary identifier of the first target network element consists of the identifier of the NRF network element and information on the NRF network element used to uniquely identify the first target network element. The identifier of the first routing network element may include one or more of the following: the area identifier of the first routing network element, the set identifier of the first routing network element, and a pointer to the first routing network element. The identifier of the NRF network element may include one or more of the following: the area identifier of the NRF network element, the set identifier of the NRF network element, and a pointer to the NRF network element.

[0029] The above technical solution provides the parameter types included in the temporary identifier of the first target network element. When the first routing network element or other routing network elements receive an uplink NAS message, they can determine which device / network element to request the internal identifier of the first target network element from, or which device / network element to forward the uplink NAS message to, based on the temporary identifier of the first target network element contained in the uplink NAS message. For example, when the temporary identifier of the first target network element includes the identifier of the first routing device, other routing network elements can request the mapping relationship from the first routing device, or forward the uplink NAS message to the first routing device; as another example, when the temporary identifier of the first target network element includes the identifier of the NRF network element, other routing network elements can request the mapping relationship from the NRF network element. This achieves the routing of the uplink NAS message.

[0030] In one possible implementation, the first routing network element may also store a mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element. Upon receiving a subsequent uplink NAS message (e.g., a second uplink NAS message), the first routing network element can determine the internal identifier of the first target network element based on the temporary identifier of the first target network element carried in the uplink NAS message, and the stored (or pre-stored) mapping relationship between the internal identifier and the temporary identifier of the first target network element, thereby routing the uplink NAS message.

[0031] In one possible implementation, when the first routing network element sends the temporary identifier of the first target network element to the terminal, it may specifically be that the temporary identifier of the first target network element is sent to the terminal if there are subsequent uplink NAS messages between the terminal and the first target network element. For example, the first routing network element determines that there are subsequent uplink NAS messages between the terminal and the first target network element.

[0032] In the above technical solution, the first routing network element can determine whether to send a temporary identifier of the first target network element to the terminal. For example, after obtaining the temporary identifier of the first target network element from the network element discovery response, the first routing network element can send the temporary identifier of the first target network element to the terminal if it determines that there are subsequent uplink NAS messages between the terminal and the first target network element. Alternatively, if the first routing network element determines that there are subsequent uplink NAS messages between the terminal and the first target network element, it generates a temporary identifier of the first target network element and sends it to the terminal. Thus, when the terminal subsequently needs to send an uplink NAS message (e.g., a second uplink NAS message) to the first target network element, it can carry the temporary identifier of the first target network element in the uplink NAS message for routing.

[0033] It is also understandable that, if no further uplink NAS messages occur between the terminal and the first target network element, the first routing network element may not send the temporary identifier of the first target network element to the terminal. For example, even if the first routing network element obtains the temporary identifier of the first target network element from the network element discovery response, it may not need to send the temporary identifier of the first target network element to the terminal, which helps reduce the signaling overhead between the first routing network element and the terminal. Furthermore, the first routing network element does not need to generate the temporary identifier of the first target network element, which helps save the computational load of the first routing network element and reduce the signaling overhead between the first routing network element and the terminal.

[0034] In one possible implementation, the first routing network element may also receive a second uplink NAS message from the terminal, wherein the second uplink NAS message includes a temporary identifier of the first target network element. The first routing network element can determine the internal identifier of the first target network element based on the temporary identifier of the first target network element, and then send the second uplink NAS message to the first target network element based on the internal identifier of the first target network element.

[0035] For example, the first routing network element can determine the internal identifier of the first target network element based on the temporary identifier of the first target network element and the mapping relationship between the temporary identifier and the internal identifier of the first target network element stored locally.

[0036] For example, the source of the second uplink NAS message is the terminal. This second uplink NAS message is sent by the terminal to the first routing network element, or it is sent by the terminal to the second routing network element and forwarded by the second routing network element to the first routing network element.

[0037] In the above technical solution, the terminal can carry a temporary identifier of the first target network element in the second uplink NAS message. The temporary identifier of the first target network element can be used by the first routing network element (or the second routing network element) to route the second uplink NAS message.

[0038] In one possible implementation, the first routing network element may also receive a first request from the second routing network element. The first request includes a temporary identifier of the first target network element, and is used to request the internal identifier of the first target network element. In one example, the first routing network element sends the internal identifier of the first target network element to the second routing network element based on the temporary identifier of the first target network element. In yet another example, the first routing network element sends a mapping relationship between the internal identifier and the temporary identifier of the first target network element to the second routing network element based on the temporary identifier of the first target network element.

[0039] In the above technical solution, the terminal can carry the temporary identifier of the first target network element in the second uplink NAS message, and the second uplink NAS message is sent by the terminal to the second routing network element. However, since the second routing network element does not store the mapping relationship between the temporary identifier and the internal identifier of the first target network element, the second routing network element also requests the internal identifier of the first target network element from the first routing network element, and then sends the second uplink NAS message to the first target network element according to the internal identifier of the first target network element, thereby realizing the routing of the second uplink NAS message.

[0040] In one possible implementation, the first routing network element may also receive a third uplink NAS message from the terminal. This third uplink NAS message includes a temporary identifier of the second target network element, which in turn includes the identifier of the third routing network element. The second target network element is the network element used to process the third uplink NAS message. The first routing network element sends a second request to the third routing network element. This second request includes the temporary identifier of the second target network element and is used to request the internal identifier of the second target network element. The first routing network element receives the internal identifier of the second target network element from the third routing network element and then sends the third uplink NAS message to the second target network element.

[0041] In the above technical solution, the first routing network element can also receive a third uplink NAS message from the terminal. Since the first routing network element does not store the mapping relationship between the temporary identifier and the internal identifier of the second target network element, the first routing network element can determine the routing network element indicated by the temporary identifier of the second target network element and request the internal identifier of the second target network element from that routing network element in order to realize the routing of the uplink NAS message.

[0042] Alternatively, the first routing network element sends a second request to the third routing network element. This second request requests a mapping between the internal identifier and temporary identifier of the second target network element, and includes the temporary identifier of the second target network element. The third routing network element receives the second request from the first routing network element and, based on the temporary identifier of the second target network element in the second request, sends the mapping between the temporary identifier and the internal identifier of the second target network element to the first routing network element. The first routing network element determines the internal identifier of the second target network element based on this mapping. The first routing network element then sends a third uplink NAS message to the second target network element based on the internal identifier of the second target network element.

[0043] In the above technical solution, the first routing network element can also determine the routing network element indicated by the temporary identifier of the second target network element, and request the mapping relationship between the temporary identifier of the second target network element and the internal identifier of the second target network element from the routing network element, so as to realize the routing of the uplink NAS message.

[0044] Alternatively, the first routing network element sends a third uplink NAS message to the third routing network element. The third routing network element receives the third uplink NAS message from the first routing network element, determines the internal identifier of the second target network element based on the mapping relationship between the temporary identifier of the second target network element and the internal identifier of the second target network element in the third uplink NAS message, and then sends the third uplink NAS message to the second target network element.

[0045] In the above technical solution, the first routing network element can also determine the routing network element indicated by the temporary identifier of the second target network element, send a third uplink NAS message to the routing network element, and the routing network element indicated by the temporary identifier routes the third uplink NAS message.

[0046] In one possible implementation, the first routing network element can also receive a third uplink NAS message from the terminal. This third uplink NAS message includes a temporary identifier of the second target network element, which in turn includes the identifier of the NRF network element. The second target network element is the network element used to process the third uplink NAS message. The first routing network element sends a second request to the NRF network element to request the internal identifier of the second target network element; or, to request the mapping relationship between the temporary identifier of the second target network element and the internal identifier of the second target network element. For details, please refer to the implementation method described above where the first routing network element sends a second request to the third routing network element; further elaboration is not required here.

[0047] Secondly, this application provides a communication method and apparatus, which can be executed by a terminal device.

[0048] Terminal devices include, for example, terminals or communication and / or computing modules within terminals, or circuits or chips within terminals responsible for communication functions (such as modem chips, also known as baseband chips, or system-on-chip (SoC) chips or system-in-package (SIP) chips containing modem cores), or circuits or chips within terminals responsible for communication and / or computing functions (such as graphics processing units (GPUs), AI processors, or application-specific integrated circuits (ASICs)), or logical nodes, logical modules, or software capable of implementing all or part of the terminal functions.

[0049] Taking the execution of this method by a terminal as an example, it should be understood that the terminal can be replaced by a terminal device, and the method includes:

[0050] The terminal sends a first uplink NAS message and first information. The first information is used to identify a first target network element, which is the network element used to process the first uplink NAS message. The terminal receives a first downlink NAS message and a temporary identifier of the first target network element. The temporary identifier of the first target network element is used for routing subsequent uplink NAS messages.

[0051] For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0052] It should be noted that the first information can be located outside or inside the first uplink NAS message. In both cases, it can be considered that the terminal sends the first uplink NAS message and the first information. Similarly, the temporary identifier of the first target network element can be located outside or inside the first downlink NAS message. In both cases, it can be considered that the terminal receives the first downlink NAS message and the temporary identifier of the first target network element.

[0053] In one possible implementation, the first information includes one or more of the following: EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. The EPD is used to indicate the NAS type, which may include, for example, session management type or mobility management type.

[0054] In one possible implementation, the temporary identifier of the first target network element includes one or more of the following: the identifier of the first routing device (i.e., the first routing network element), information on the first routing device (i.e., the first routing network element) used to uniquely identify the first target network element, the identifier of the NRF network element, and information on the NRF network element used to uniquely identify the first target network element. It can be understood that the first routing device is a device that stores the mapping relationship between the temporary identifier and the internal identifier of the first target network element (for example, the first routing device is used to route a second uplink NAS message, and the target network element of the second uplink NAS message is the first target network element; or, for example, the first routing device is used to provide the mapping relationship); the NRF network element is the network element used to discover the first target network element in the network element discovery process; furthermore, the NRF network element can also be a network element that stores the mapping relationship between the temporary identifier and the internal identifier of the first target network element (for example, it is also a network element that provides the mapping relationship).

[0055] In one possible implementation, the terminal may further determine that the temporary identifier of the first target network element is not included in the first uplink NAS message if it has not obtained the temporary identifier of the first target network element. That is, the first uplink NAS message does not include the temporary identifier of the first target network element. In one possible example, the terminal sets the value of the receiver information field in the first uplink NAS message to empty if it has not obtained the temporary identifier of the first target network element. For example, the receiver information field is located in the header of the first uplink NAS message.

[0056] In one possible implementation, the terminal determines that it has not obtained the temporary identifier of the first target network element before generating the first uplink NAS message. For example, before generating the first uplink NAS message, the terminal determines that it has not obtained the temporary identifier of the first target network element based on fourth information. The content of the fourth information may be the same as or different from the content of the first information. For example, the fourth information includes one or more of EPD, NAS type, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. For example, the fourth information is determined by the terminal based on the first uplink NAS message to be sent (or generated).

[0057] In one possible implementation, before generating the second uplink NAS message, the terminal may obtain a temporary identifier of the first target network element. For example, based on the second uplink NAS message to be sent (or generated), the terminal determines fourth information and obtains the temporary identifier of the first target network element according to the fourth information. The terminal sends the second uplink NAS message, which includes the temporary identifier of the first target network element. The temporary identifier of the first target network element is used for routing the second uplink NAS message. For example, the value of the receiver information field in the first uplink NAS message is set to the temporary identifier of the first target network element.

[0058] In one possible implementation, after receiving the first downlink NAS message and the temporary identifier of the first target network element, the terminal can also save the mapping relationship between the temporary identifier of the first target network element and the first information.

[0059] In one possible implementation, after the terminal saves the mapping relationship between the temporary identifier of the first target network element and the first information, it can also obtain the temporary identifier of the first target network element based on the saved mapping relationship and the fourth information before generating the second uplink NAS message. The terminal sends the second uplink NAS message, which includes the temporary identifier of the first target network element.

[0060] In one possible implementation, the terminal further sends a third uplink NAS message, which includes a temporary identifier of the second target network element. The temporary identifier of the second target network element includes an identifier of a third routing network element, which is a network element used to process the third uplink NAS message. The identifier of the third routing network element is used by the routing network element (e.g., the first routing network element) to route the third uplink NAS message to the third routing network element, or to request the internal identifier of the second target network element from the third routing network element.

[0061] In one possible implementation, the terminal further sends a third uplink NAS message, which includes a temporary identifier of the second target network element. The temporary identifier of the second target network element may also include the identifier of the NRF network element. The second target network element is a network element used to process the third uplink NAS message. The identifier of the NRF network element is used by the routing network element (e.g., the first routing network element) to request the internal identifier of the second target network element from the NRF network element.

[0062] Thirdly, this application provides a communication method and apparatus, which can be executed by a second routing device.

[0063] The second routing device is, for example, a second routing network element or a module (e.g., a chip) within a second routing network element. The second routing network element may also be referred to as a second routing function network element, a second NAS routing network element, a second NAS routing function network element, a second CPF network element, a second SRF network element, etc.

[0064] Taking the execution of this method by a second routing network element as an example, it should be understood that the second routing network element can be replaced by a second routing device. The methods include:

[0065] The second routing network element receives a second uplink NAS message from the terminal. This second uplink NAS message includes a temporary identifier of the first target network element, which in turn includes the identifier of the first routing network element. The first target network element is the network element used to process the second uplink NAS message. Based on the identifier of the first routing network element, the second routing network element sends the second uplink NAS message to the first routing network element, which then routes the second uplink NAS message to the first target network element. Alternatively,

[0066] The second routing network element receives a second uplink NAS message from the terminal. This second uplink NAS message includes a temporary identifier of the first target network element, which in turn includes the identifier of the first routing network element. The first target network element is the network element used to process the second uplink NAS message. The second routing network element sends a first request to the first routing network element. This first request includes the temporary identifier of the first target network element and is used to request the internal identifier of the first target network element. The second routing network element receives the internal identifier of the first target network element from the first routing network element and sends the second uplink NAS message to the first target network element. Alternatively, the second routing network element receives a mapping relationship between the internal identifier and the temporary identifier of the first target network element from the first routing network element and sends the second uplink NAS message to the first target network element according to the mapping relationship.

[0067] Fourthly, this application provides a communication method and apparatus, which can be executed by a third routing device.

[0068] The third routing device is, for example, a third routing network element or a module (e.g., a chip) within a third routing network element. The third routing network element can also be referred to as a third routing function network element, a third NAS routing network element, a third NAS routing function network element, a third CPF network element, a third SRF network element, etc.

[0069] Taking the execution of this method by a third-party routing network element as an example, it should be understood that the third-party routing network element can be replaced by a third-party routing device. The methods include:

[0070] The third routing network element receives a second request from the first routing network element. The second request includes a temporary identifier for the second target network element and is used to request the internal identifier of the second target network element. The third routing network element sends the internal identifier of the second target network element to the first routing network element. For example, the third routing network element determines the internal identifier of the second target network element based on its temporary identifier. Alternatively,

[0071] The third routing network element receives a second request from the first routing network element. The second request includes a temporary identifier for the second target network element and is used to request the internal identifier of the second target network element. The third routing network element sends the mapping relationship between the internal identifier and the temporary identifier of the second target network element to the first routing network element. For example, the third routing network element determines the mapping relationship between the internal identifier and the temporary identifier of the second target network element based on the temporary identifier and sends the mapping relationship to the first routing network element. Alternatively,

[0072] The third routing network element receives a third uplink NAS message from the first routing network element. This third uplink NAS message includes a temporary identifier of the second target network element, which in turn includes the identifier of the third routing network element. The second target network element is the network element used to process the third uplink NAS message. Based on the temporary identifier of the second target network element, the third routing network element determines the internal identifier of the second target network element and sends the third uplink NAS message to it. The third uplink NAS message is sent from the terminal to the first routing network element.

[0073] Fifthly, this application provides a communication method and apparatus, which can be executed by a network element storage device.

[0074] Network element storage devices are used to provide network element information during the network element discovery process. Network element storage devices are, for example, NRF network elements or modules (e.g., chips) within NRF network elements.

[0075] Taking the execution of this method on an NRF network element as an example, it should be understood that the NRF network element can be replaced with a network element storage device. The methods include:

[0076] The NRF network element receives a network element discovery request from the first routing network element. Based on the network element discovery request, the NRF network element sends a temporary identifier and an instance identifier of the first target network element to the first routing network element.

[0077] In one possible implementation, the temporary identifier of the first target network element includes one or more of the following: the identifier of the first routing device (i.e., the first routing network element), information on the first routing device (i.e., the first routing network element) used to uniquely identify the first target network element, the identifier of the network element storage device (i.e., the NRF network element), and information on the network element storage device (i.e., the NRF network element) used to uniquely identify the first target network element.

[0078] In one possible implementation, the network element discovery request is used to instruct the NRF network element to generate a temporary identifier for the first target network element.

[0079] For example, an NRF network element can not only determine the first target network element based on the network element discovery request, but also generate a temporary identifier for the first target network element based on the network element discovery request.

[0080] For example, the network element discovery request may also carry third information, which may include one or more of the following: NAS type, NAS message type, indication of generating a temporary identifier for the first target network element, indication of the existence of downlink NAS messages in the network, indication of the existence of other uplink NAS messages in the network, consumer field, and service name field. The consumer field is the identifier of the first routing network element; the service name field is the service that forwards the NAS message. The third information can be used to instruct the NRF network element to generate a temporary identifier for the first target network element.

[0081] Sixthly, embodiments of this application provide a communication device.

[0082] The device has the function of implementing the first aspect or any possible implementation of the first aspect. The device can be a first routing network element or a module (such as a chip) in the first routing network element.

[0083] The device has the function of implementing the terminal in the second aspect or any possible implementation of the second aspect. The device can be a terminal or a module (such as a chip) in the terminal.

[0084] The device has the function of implementing the second routing device in the third aspect or any possible implementation of the third aspect. The device can be a second routing network element or a module (such as a chip) in the second routing network element.

[0085] The device has the function of implementing the third routing device in the fourth aspect or any possible implementation of the fourth aspect. The device can be a third routing network element or a module (such as a chip) in the third routing network element.

[0086] The device has the function of implementing the network element storage device in the fifth aspect or any possible implementation of the fifth aspect. The device can be an NRF network element or a module (such as a chip) in an NRF network element.

[0087] The functions of the aforementioned communication device can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules, units, or means corresponding to the aforementioned functions.

[0088] In one possible implementation, the device includes a processing module and a transceiver module, wherein the processing module is configured to support the device.

[0089] Perform the corresponding method of the first routing device in the first aspect or any implementation thereof, or

[0090] Perform the corresponding method of the terminal device in the second aspect or any implementation thereof, or

[0091] Perform the corresponding method of the second routing device in the third aspect or any implementation thereof, or

[0092] Perform the corresponding method of the third routing device in the fourth aspect or any implementation thereof, or

[0093] The method for performing the network storage function device in the fifth aspect or any implementation thereof.

[0094] The transceiver module supports communication between the device and other communication devices. For example, when the device is a first routing device, it can receive the first uplink NAS message from the terminal. The communication device may also include a storage module coupled to the processing module, which stores the necessary program instructions and data for the device. As an example, the processing module can be a processor, the communication module can be a transceiver, and the storage module can be a memory. The memory can be integrated with the processor or separated from it.

[0095] In another possible implementation, the device includes a processor and may also include a memory. The processor is coupled to the memory and can be used to execute computer program instructions stored in the memory to enable the device...

[0096] Perform the corresponding method of the first routing device in the first aspect or any implementation thereof, or

[0097] Perform the corresponding method of the terminal device in the second aspect or any implementation thereof, or

[0098] Perform the corresponding method of the second routing device in the third aspect or any implementation thereof, or

[0099] Perform the corresponding method of the third routing device in the fourth aspect or any implementation thereof, or

[0100] The method for performing the network storage function device in the fifth aspect or any implementation thereof described above.

[0101] Optionally, the device further includes a communication interface, to which the processor is coupled. When the device is a network element / device, the communication interface can be a transceiver or an input / output interface; when the device is a chip included in a network element / device, the communication interface can be the chip's input / output interface. Optionally, the transceiver can be a transceiver circuit, and the input / output interface can be an input / output circuit.

[0102] In a seventh aspect, embodiments of this application provide a chip system, including: a processor and a memory, wherein the processor is coupled to the memory, and the memory is used to store programs or instructions, and when the program or instructions are executed by the processor, the chip system causes...

[0103] Perform the corresponding method of the first routing device in the first aspect or any implementation thereof, or

[0104] Perform the corresponding method of the terminal device in the second aspect or any implementation thereof, or

[0105] Perform the corresponding method of the second routing device in the third aspect or any implementation thereof, or

[0106] Perform the corresponding method of the third routing device in the fourth aspect or any implementation thereof, or

[0107] The method for performing the network storage function device in the fifth aspect or any implementation thereof described above.

[0108] Optionally, the chip system also includes an interface circuit for exchanging code instructions with the processor.

[0109] Optionally, the chip system may include one or more processors, which can be implemented in hardware or software. When implemented in hardware, the processor may be a logic circuit, integrated circuit, etc. When implemented in software, the processor may be a general-purpose processor that reads software code stored in memory.

[0110] Optionally, the chip system may contain one or more memories. These memories may be integrated with the processor or disposed separately. For example, the memory may be a non-transitory processor, such as read-only memory (ROM), which may be integrated with the processor on the same chip or disposed on separate chips.

[0111] Eighthly, this application provides a computer-readable storage medium storing a computer program or instructions, which, when executed by a communication device, cause the communication device to...

[0112] Perform the corresponding method of the first routing device in the first aspect or any implementation thereof, or

[0113] Perform the corresponding method of the terminal device in the second aspect or any implementation thereof, or

[0114] Perform the corresponding method of the second routing device in the third aspect or any implementation thereof, or

[0115] Perform the corresponding method of the third routing device in the fourth aspect or any implementation thereof, or

[0116] The method for performing the network storage function device in the fifth aspect or any implementation thereof described above.

[0117] Ninthly, this application provides a computer program product comprising a computer program or instructions, which, when executed by a communication device,

[0118] The method for implementing the first routing device in the first aspect or any implementation of the first aspect, or

[0119] The method for implementing the terminal device in the second aspect or any implementation of the second aspect, or

[0120] The method for implementing the second routing device in the third aspect or any implementation of the third aspect, or

[0121] The method for implementing the third routing device in the fourth aspect or any implementation of the fourth aspect, or

[0122] A method for implementing the network storage function device in the fifth aspect or any of the implementations of the fifth aspect.

[0123] Tenthly, embodiments of this application provide a communication system, which includes one or more of the following:

[0124] The first routing device in the first aspect or any implementation thereof;

[0125] The terminal device in the second aspect or any implementation thereof;

[0126] The second routing device in the third aspect or any implementation thereof;

[0127] The third routing device in the fourth aspect or any implementation thereof; or,

[0128] The network storage function device in the fifth aspect or any implementation thereof.

[0129] Eleventhly, embodiments of this application provide a communication system, the communication system comprising: a first routing device and a first target network element; wherein, the first routing device is configured to execute the method in the first aspect or any implementation thereof; the first target network element is configured to receive a first uplink NAS message from the first routing device, and to send a first downlink NAS message to the first routing device.

[0130] In one possible implementation, the communication system further includes a terminal device for implementing the method in the second aspect or any implementation thereof.

[0131] In one possible implementation, the communication system further includes a network storage function device, which is used to implement the method in the fifth aspect or any implementation of the fifth aspect.

[0132] The technical effects that can be achieved by any of the second to eleventh aspects mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0133] Figure 1 This is a schematic diagram of a communication network architecture;

[0134] Figure 2 This is a schematic diagram of a possible terminal registration process;

[0135] Figure 3 This is a schematic diagram of a 5G GUTI structure;

[0136] Figure 4 A schematic diagram illustrating the process of establishing a possible session;

[0137] Figure 5 This is a schematic diagram illustrating the routing process of uplink NAS messages by an AMF network element.

[0138] Figure 6 A schematic diagram of a message routing architecture provided for this application;

[0139] Figure 7 A flowchart illustrating the first communication method provided in this application;

[0140] Figure 8 A flowchart illustrating the second communication method provided in this application;

[0141] Figure 9 A flowchart illustrating the third communication method provided in this application;

[0142] Figure 10 A flowchart illustrating the fourth communication method provided in this application;

[0143] Figure 11 A flowchart illustrating the fifth communication method provided in this application;

[0144] Figure 12 A flowchart illustrating the sixth communication method provided in this application;

[0145] Figure 13 A schematic diagram of the structure of the seventh type of communication device provided in this application;

[0146] Figure 14 A schematic diagram of the structure of a communication device provided in this application;

[0147] Figure 15 A schematic diagram of another communication device provided in this application. Detailed Implementation

[0148] The relevant technical features involved in the embodiments of this application will be explained below. It should be noted that these explanations are for the purpose of making the embodiments of this application easier to understand, and should not be regarded as a limitation on the scope of protection claimed by this application.

[0149] I. Communication Network Architecture

[0150] Figure 1 This is a schematic diagram of a communication network architecture. Figure 1 The communication network architecture shown can be divided into three parts: the terminal part, the data network (DN), and the carrier network part. The functions of some of these network elements are briefly described below.

[0151] The operator network may include one or more of the following network elements (or devices, functions, nodes): radio access node (RAN), authentication server function (AUSF) network element, network exposure function (NEF) network element, policy control function (PCF) network element, unified data management (UDM) network element, unified data repository (UDR) network element, NRF network element, AMF network element, SMF network element, user plane function (UPF) network element, application function (AF) network element, etc.

[0152] A terminal, also known as user equipment (UE) or terminal device, is a device with wireless transceiver capabilities. It can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water (such as on ships); and in the air (such as on airplanes, balloons, and satellites). Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, virtual reality (VR) terminals, augmented reality (AR) terminals, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, and wireless terminals in smart homes, among others.

[0153] The aforementioned terminals can establish connections with the operator's network through interfaces provided by the operator's network (such as N1), and use data and / or voice services provided by the operator's network. The terminals can also access the DN (Network Provider) through the operator's network, and use operator services deployed on the DN, and / or services provided by third parties. These third parties can be service providers outside of the operator's network and the terminals, and can provide data and / or voice services to the terminals. The specific form of these third parties can be determined according to the actual application scenario and is not limited here.

[0154] RAN (Radio Access Registry) is used to provide network access functionality for authorized terminals in a specific area, and can use transmission tunnels with different quality of service based on the terminal's level and service requirements. RAN manages radio resources, provides access services to terminals, and forwards control signals and data between the terminal and the core network. RAN can also be understood as a base station in a traditional network. For example, RAN can be any communication device with wireless transceiver capabilities used to communicate with terminals. This RAN includes, but is not limited to, evolved Node B (eNB), next-generation Node B (gNB) in a 5G system, or transmission reception point (TRP), or one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system. It can also be a network node constituting a gNB or transmission point, such as a base band unit (BBU), or a distributed unit (DU), or it can be a pole station, micro base station, macro station, integrated access and backhaul (IAB) node, etc.

[0155] The core network includes user plane functions and control plane functions.

[0156] User plane functions include UPF network elements. As the interface with the data network, UPF network elements perform functions such as forwarding user plane data (e.g., packet data packets), quality of service (QoS) control, session / flow-based billing statistics, and bandwidth limiting.

[0157] The control plane functions primarily handle user registration and authentication, mobility management, and the distribution of packet forwarding policies and QoS control policies to the user plane functions. The control plane functions can be further refined to include other network elements besides the UPF element, such as the AMF and SMF elements.

[0158] The AMF (Application Function Provider) network element primarily handles the user registration process upon access, as well as location management and access authentication / authorization during user movement. Additionally, it is responsible for transmitting user policies between the terminal and the PCF (Application Processing Provider) network element.

[0159] The SMF network element is mainly responsible for establishing corresponding session connections when users initiate services and providing specific services to users, such as sending data packet forwarding policies and QoS policies to the UPF network element based on the NG4 interface between the SMF network element and the UPF network element.

[0160] The AUSF network element is mainly responsible for authenticating users and determining the legitimacy of the terminal in order to decide whether to allow the terminal to access the network.

[0161] UDM network elements are mainly responsible for storing terminal subscription data, user access authorization, and other functions.

[0162] The UDR network element is mainly responsible for storing and retrieving data of various types, such as contract data, policy data, and application data.

[0163] The PCF network element is mainly responsible for issuing service-related policies to the AMF or SMF network elements.

[0164] NEF network elements are primarily used to support the opening of capabilities and events.

[0165] The AF (Application Provider) network element primarily transmits application-side requirements to the PCF (Application Function) network element, enabling the PCF network element to generate corresponding policies. The AF network element can be a third-party functional entity or an application service deployed by the operator, such as Internet Protocol (IP) Multimedia Subsystem (IMS) voice call services.

[0166] NRF network elements can be used to provide network element discovery functionality, providing network element information corresponding to the network element type based on requests from other network elements. NRF network elements also provide network element management services, such as network element registration, updates, deregistration, and network element status subscription and push.

[0167] A Domain Provider (DN) is a network located outside of the carrier's network. A carrier's network can connect to multiple DNs, and various services can be deployed on a DN, providing data and / or voice services to terminals. For example, a DN might be the private network of a smart factory. Sensors installed in the workshop can act as terminals, and a control server for these sensors is deployed within the DN. The control server provides services to the sensors. Sensors can communicate with the control server, receive instructions from it, and transmit the collected sensor data back to the control server accordingly. Another example is a DN serving as an internal office network for a company. Employees' mobile phones or computers can act as terminals, accessing information and data resources on the company's internal office network.

[0168] Figure 1 Nnssf, Nausf, Nnef, Nnrf, Npcf, Nudm, Naf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface sequence numbers. The meanings of these interface sequence numbers can be found in the definitions of the 3rd Generation Partnership Project (3GPP) protocol, and are not limited here.

[0169] It is understood that the aforementioned network element can be a network component in a hardware device, a software function running on dedicated hardware, or a virtualization function instantiated on a platform (e.g., a cloud platform). Optionally, the aforementioned network element can be implemented by a single device, multiple devices working together, or a functional module within a single device; this application does not specifically limit this.

[0170] The network element involved in the embodiments of this application can be Figure 1 The AMF, SMF, and NRF network elements mentioned above can also refer to network elements in future communication networks that possess the functions of the aforementioned AMF, SMF, and NRF network elements. In future communication networks, these network elements may retain their original names or be referred to by other names. This application does not limit the specific names used in its embodiments.

[0171] In this application, a network element may also be referred to as a network function (NF) device, NF node, NF network element, etc.

[0172] II. Terminal Registration Process

[0173] Figure 2 This is a schematic diagram of a possible terminal registration process provided in an embodiment of this application, wherein, Figure 2 The main focus is on how AMF network elements route NAS messages (such as messages between AMF network elements and terminals) and N2 messages (such as messages between AMF network elements and RAN). This process includes:

[0174] Step 201: The terminal sends a registration request message to the RAN.

[0175] For example, the terminal and the RAN can establish an air interface (also simply called the air interface). The RAN stores the terminal's identifier, such as (e.g., the terminal's temporary identifier on the air interface, the radio network temporary identity (RNTI), etc.). When initiating registration, the terminal can send a registration request message to the RAN. For example, the registration request message includes the terminal's subscription concealed identifier (SUCI), access network (AN) parameters, etc. The registration request message is a NAS message.

[0176] Step 202: RAN selects AMF network element.

[0177] In one specific implementation, the RAN selects an AMF network element that has already established a next-generation application protocol (NGAP) connection with the RAN, based on the radio access technology (RAT) information currently accessed by the terminal and the terminal's slice information in the AN parameters.

[0178] Step 203: The RAN sends an initial UE message to the AMF network element.

[0179] The initial terminal message may include the RAN UE NGAP ID (i.e., the NGAP identifier (identity, ID) assigned to the terminal by the RAN) and the terminal's registration request message (i.e., the NAS message, which includes the terminal's SUCI).

[0180] Step 204: The AMF network element sends an initial context setup request message to the RAN.

[0181] The initial context establishment request message may include the RAN UE NGAP ID, the AMF UE NGAP ID (i.e., the NGAP identifier assigned to the terminal by the AMF network element), and a registration accept message sent to the terminal. The registration accept message may include, for example, a 5G-Globally Unique Temporary UE Identity (GUTI) assigned to the terminal by the AMF network element (i.e., 5G-GUTI). The registration accept message is a NAS message.

[0182] In step 205, the RAN sends a registration acceptance message to the terminal.

[0183] For example, the structure of 5G GUTI can be as follows: Figure 3 As shown, the 5G GUTI includes the mobile country code (MCC), mobile network code (MNC), AMF region ID, AMF set ID, AMF pointer, and 5G temporary mobile subscriber identity (TMSI).

[0184] Among them, MCC and MNC constitute the public land mobile network (PLMN) identifier, which can be used to represent the identifier of the PLMN where the AMF network element is located or the identifier of the PLMN accessed by the terminal; AMF area identifier, AMF set identifier, and AMF pointer constitute the AMF network element identifier; 5G-TMSI is a temporary identifier assigned to the terminal; MCC, MNC, and AMF network element identifier constitute the globally unique AMF identifier (GUAMI); AMF set identifier, AMF pointer, and 5G-TMSI constitute the 5G short-temporary mobile subscriber identity (5G-S-TMSI).

[0185] At this point, the RAN can store the terminal's identifiers on the air interface connection (such as RNTI), the terminal's identifiers on the NGAP connection (i.e., AMF UE NGAP ID and RAN UE NGAP ID), and information about the AMF network elements serving the terminal (such as identifiers). All of this information is stored in the terminal context (UE context) and is interconnected. The AMF network elements store the terminal's subscription permanent identifier (SUPI), the terminal's identifiers on the NGAP connection (i.e., AMF UE NGAP ID and RAN UE NGAP ID), and information about the RAN serving the terminal (such as identifiers). All of this information is stored in the terminal context and is also interconnected. The SUPI can be decrypted from the terminal's SUCI. The AMF UE NGAP ID and RAN UE NGAP ID can be called an NGAP ID pair.

[0186] It should be noted that the terminal registration process may also involve other network elements, such as PCF network elements, SMF network elements, AUSF network elements, etc.; there may also be other steps before step 204, such as the selection of AUSF network elements and security authentication.

[0187] After the terminal registration process, the following steps can also be performed:

[0188] (1) Other network elements (e.g., SMF network elements) can send messages to the terminal through AMF network elements. Specifically, other network elements can request the Communication_N1N2MessageTransfer service of AMF network elements and specify the target terminal using SUPI. AMF network elements determine the RAN and NGAP ID pair serving the terminal based on SUPI and then route the message down.

[0189] (2) Other network elements (e.g., SMF network elements) can send messages to the RAN serving the terminal through the AMF network element. Specifically, other network elements also request the Communication_N1N2MessageTransfer service of the AMF network element, use SUPI to specify the target terminal, the AMF network element determines the RAN serving the terminal through SUPI, and then routes the message down.

[0190] III. Session Establishment Process

[0191] Figure 4 This is a schematic diagram of a possible session establishment process provided in an embodiment of this application. Figure 4 The main focus is on the transmission path of uplink messages from the terminal. For example, uplink messages may be sent to AMF network elements as well as SMF network elements. This process includes:

[0192] Step 401: The terminal sends a Protocol Data Unit (PDU) session establishment request message to the AMF network element through the RAN. This message can be expressed as PDU session establishment request.

[0193] For example, after a terminal registers with the network, it can send a NAS PDU to the AMF network element via the RAN. Upon receiving the NAS PDU from the terminal, the RAN can send an uplink NAS transport (UL NAStransport) message to the AMF network element. This uplink NAS transport message includes information such as the RAN UE NGAP ID, AMF UE NGAP ID, terminal location, and the NAS PDU. The NAS PDU may include parameters such as the PDU session identifier, data network name (DNN), and slice information, as well as an N1 session management (SM) container. The N1 SM container may encapsulate NAS messages sent by the terminal to the SMF network element (e.g., PDU session establishment request messages).

[0194] Step 402: The AMF network element selects the SMF network element. For example, the AMF network element can select the SMF network element based on parameters such as "DNN and slice information" to obtain information such as the identifier of the SMF network element.

[0195] Step 403: The AMF network element sends a PDU session createSM context request to the SMF network element.

[0196] The request to create a session management context may include information such as the N1 SM container, the terminal's SUPI, and the identifier of the AMF network element.

[0197] AMF network elements can store the PDU session identifier and the corresponding SMF network element information (such as identifiers) in the terminal's context. SMF network elements store the terminal's SUPI, PDU session identifier, and AMF network element information (such as identifiers).

[0198] It is understandable that the session establishment process may also involve other network elements, such as UPF network elements, PCF network elements, UDM network elements, etc.; the session establishment process may also include other steps, such as the SMF network element sending a PDU session create SM context response to the AMF network element, PCF network element selection, UPF network element selection, N4 session establishment, etc.

[0199] After the session establishment process, when the terminal sends a NAS message to the SMF network element, the NAS message includes a PDU session identifier. The AMF network element can determine which SMF network element to send the NAS message to based on this PDU session identifier. The message type of this NAS message is session management (SM), meaning that this NAS message is of session management type.

[0200] Figure 5 An example is provided of an AMF network element routing NAS messages.

[0201] For NAS messages, AMF network elements can determine the routing method based on the NAS type (e.g., extended protocol discriminator, EPD) field in the header of the NAS message.

[0202] For example, if it is a NAS message of the session management type, the AMF network element can send the NAS message to the SMF network element associated with the PDU session identifier carried in the NAS message;

[0203] If it is a NAS message of the mobility management (MM) type, the AMF network element then determines whether the NAS message is sent to itself based on the message type field in the header.

[0204] For example, when the message type field indicates that the NAS message is a registration request message, service request message, etc., the AMF network element can determine that the NAS message is sent to itself.

[0205] For example, if the message type field indicates that the NAS message is an uplink NAS transmission message, then the NAS message may be sent to other network elements. In cases where the message type field indicates that the NAS message is an uplink NAS transmission message, the AMF network element can also open the NAS message's payload to view the payload containertype field. Furthermore, if the payload container type field is 0010, indicating a Short Message Service (SMS) type, the payload contains an encapsulated SMS-related message. The AMF network element routes the content of the NAS message to an SMS-related network element (such as a Short Message Service Function (SMSF) network element). If it is 0101, indicating a terminal policy container type, it means the message needs to be routed to a Policy Control Function (PCF) network element. Since the AMF network element stores the identifier of the terminal's PCF network element in the terminal context, it can use this identifier to route the content of the NAS message to the PCF network element. If it is 0111, indicating a Location Service (LCS) message container type, the AMF network element needs to route the NAS message to an LMF network element. For example, the AMF network element parses the payload of the NAS message, examines the routing identifier element within the payload, which indicates the identifier of the LMF network element, and then routes the content of the NAS message to that LMF network element.

[0206] It's important to note that a NAS message sent to an SMF network element can also be understood as an MM-type NAS message containing an SM-type NAS message. This MM NAS message is also a UL NAS transmission message. If the payload container type field is 0001, indicating N1 SM information type, then the payload contains an encapsulated SM NAS message. The AMF network element routes the content of the NAS message to the corresponding SMF network element based on the PDU session identifier in the header of this encapsulated SM NAS message.

[0207] Combination Figures 2 to 5As seen in the relevant embodiments, the AMF network element, in addition to routing messages destined for the SMF network element, also routes messages destined for other network elements. Currently, there is discussion about decoupling the routing function of the AMF network element. For example, the routing function could be handled by a new network element (this new network element is a network element / entity with routing capabilities, which can be referred to as the routing network element). For instance, this routing network element could be a different network element from the AMF network element. This would help avoid affecting the normal routing of NAS messages when the AMF network element needs to be restarted.

[0208] Optionally, routing can be understood as forwarding received messages without altering their content. Alternatively, it can be understood as performing some processing on the received messages, such as adding, deleting, or modifying fields or content before sending them to other network elements. For example, modifying the header and / or payload of a NAS message before sending it to other network elements.

[0209] like Figure 6 This is a schematic diagram of a message routing architecture. Terminals can communicate with other network elements (including AMF, SMF, LMF, etc.) through routing network elements. For example, a routing network element can forward NAS messages between an AMF network element and a terminal, or a routing network element can forward NAS messages between an SMF network element and a terminal.

[0210] Among them, routing network elements can also be called routing function network elements, NAS routing network elements, NAS routing function network elements, core network portal function (CPF) network elements, signaling routing function (SRF) network elements, etc.

[0211] based on Figure 6 In this message routing architecture, a terminal can establish a NAS connection with a single network element of the same type, such as an AMF network element or an SMF network element; alternatively, a terminal can establish NAS connections with multiple network elements of the same type, such as two AMF network elements or three SMF network elements. In this application, the architecture in which a terminal establishes NAS connections with multiple network elements is referred to as a distributed NAS architecture.

[0212] How to implement the routing of NAS messages by this routing network element is a technical problem that urgently needs to be solved.

[0213] like Figure 7 This is a flowchart illustrating a first communication method provided by example in this application. This communication method can be executed interactively by a routing device, a terminal device, and a first target network element.

[0214] The routing device has routing functionality. The routing device is, for example, a routing network element or a module (e.g., a chip) within a routing network element. Optionally, the routing network element can be implemented by one device or by multiple devices working together.

[0215] Terminal devices include, for example, terminals or communication and / or computing modules within terminals, or circuits or chips within terminals responsible for communication functions (such as modem chips, also known as baseband chips, or system-on-chip (SoC) chips or system-in-package (SIP) chips containing modem cores), or circuits or chips within terminals responsible for communication and / or computing functions (such as graphics processing units (GPUs), AI processors, or application-specific integrated circuits (ASICs)), or logical nodes, logical modules, or software capable of implementing all or part of the terminal functions.

[0216] The first target network element is the destination of the terminal sending the first uplink NAS message. The first target network element can be a network element that has established a NAS connection with the terminal. The first target network element can be an AMF network element, SMF network element, LMF network element, UPF network element, PCF network element, SMSF network element, etc. It is understood that in future communication systems, any network element capable of establishing a NAS connection with the terminal may be the first target network element in this application.

[0217] For ease of description, the following explanation uses routing network elements, NRF network elements, and terminals as examples. Furthermore, to distinguish between different routing network elements, Figure 7 The routing network element in the relevant embodiments can be referred to as the first routing network element.

[0218] Step 701: The terminal sends a first uplink NAS message and first information. This first uplink NAS message and first information are received by the first routing network element; that is, the first routing network element receives the first uplink NAS message and first information from the terminal.

[0219] The first information is used to determine the first target network element, which is the network element used to process the first uplink NAS message.

[0220] In one possible example, the terminal is unaware of the routing network element. The terminal can send a first uplink NAS message and a first information to the RAN, which then forwards the first uplink NAS message and the first information to the first routing network element. For example, the terminal sends an uplink RRC message to the RAN, which includes the first uplink NAS message and the first information; the RAN then sends an N2 message to the first routing network element, which further includes the first uplink NAS message and the first information.

[0221] It should be noted that the first information can be located outside or inside the first uplink NAS message. In both cases, it can be considered that the terminal sends both the first uplink NAS message and the first information. Furthermore, when the first information is outside the first uplink NAS message, the first uplink NAS message and the first information can be sent through the same message. Alternatively, the first uplink NAS message and the first information can be sent through two separate messages, and the order of these two messages is not limited.

[0222] In one possible approach, the first information includes or specifically includes one or more of the following: Extended Protocol Discriminator (EPD), message type, network element type, slice identifier, subnet ID, and protocol data unit (PDU) session identifier. The meaning of each parameter is illustrated below with examples:

[0223] 1. EPD is an Extended Protocol Identifier. The value of EPD indicates the extended protocol identifier corresponding to the NAS message. It can be understood that EPD indicates the NAS type of the first uplink NAS message, which can be a session management type, a mobility management type, or a sensing management type, etc. When EPD indicates that the NAS type of the first uplink NAS message is a session management type, it can be designated as EPD1, and the first uplink NAS message belongs to the session management message category; when EPD indicates that the NAS type of the first uplink NAS message is a mobility management type, it can be designated as EPD2, and the first uplink NAS message belongs to the mobility management message category; when EPD indicates that the NAS type of the first uplink NAS message is a sensing management type, it can be designated as EPD3, and the first uplink NAS message belongs to the sensing management message category. For example, based on the value of EPD, EPD can be divided into EPD1 and EPD2. For example, EPD occupies 8 bits, the value of EPD1 is 00101110, the value of EPD2 is 01111110, and the value of EPD3 is 00101100.

[0224] For example, when the first information is located inside the first uplink NAS message, the EPD is located in the header of the first uplink NAS message.

[0225] In this application, the first information can also be considered to include a NAS type, such as a session management type or a mobility management type. That is, the EPD can be replaced with the NAS type. Furthermore, the EPD can also indicate the NAS type of the downlink NAS message. Uplink NAS messages and downlink NAS messages of the same NAS type can have the same EPD.

[0226] 2. The message type is used to indicate the specific type of the first uplink NAS message.

[0227] For example, the message type is at least one or more of the following:

[0228] 1) PDU session establishment request;

[0229] 2) PDU session modification request;

[0230] 3) PDU session release request;

[0231] 4) Registration request;

[0232] 5) Service request.

[0233] For example, when the first information is located inside the first uplink NAS message, the message type can be located in the header or payload of the first uplink NAS message.

[0234] It is understood that when the first information includes EPD and message type, the two are related. For example, when the message type is any of 1) to 3) above, the EPD indicates that the first uplink NAS message is a session management type; when the message type is 4) or 5) above, the EPD indicates that the first uplink NAS message is a mobility management type.

[0235] 3. Network element type indicates the type of the first target network element, that is, from which type of network element should the first target network element be determined. Network element types include, for example, SMF network element type, AMF network element type, LMF network element type, etc.

[0236] For example, when the first information is located inside the first uplink NAS message, the network element type is located in the header of the first uplink NAS message.

[0237] It is understandable that when the first information includes EPD and network element type, the two are related. For example, when EPD indicates that the first uplink NAS message is of session management type, the network element type is SMF network element type; when EPD indicates that the first uplink NAS message is of mobility management type, the network element type is AMF network element type.

[0238] When the first information includes message type and network element type, the two are related. For example, when the message type is any one of 1) to 3) above, the network element type is SMF network element type; when the message type is 4) or 5) above, the network element type is AMF network element type.

[0239] 4. Slice identifiers are used to indicate slices. For example, the slice identifier in an uplink NAS message can be used to indicate the slice the terminal requests to access or the slice supported by the first target network element. That is, it indicates from which network elements supporting a slice the first target network element needs to be determined. Slice identifiers can be used to ensure that the discovered network elements can support the service requirements of a specific slice (such as low latency and high bandwidth). Slice identifiers can be, for example, single network slice selection assistance information (S-NSSAI).

[0240] For example, when the first information is located inside the first uplink NAS message, the slice identifier can be located in the header or payload of the first uplink NAS message.

[0241] 5. Subnet identifiers are used to indicate subnets. For example, the subnet identifier in an uplink NAS message can be used to indicate the subnet the terminal requests access to or the subnet where the first target network element is located; that is, it indicates from which subnet the first target network element needs to be determined. As another example, subnet identifiers can be used to limit the geographical, logical, or network scope of network element discovery, thereby optimizing the use of network resources and reducing latency.

[0242] For example, when the first information is located inside the first uplink NAS message, the subnet identifier is located in the header or payload of the first uplink NAS message.

[0243] 6. PDU Session Identifier: The PDU session identifier is used to identify the session. For example, when the first information is located inside the first uplink NAS message, the PDU session identifier can be located in the header or payload of the first uplink NAS message.

[0244] In this application, slice identifier, subnet identifier, and PDU session identifier can be collectively referred to as service identifier, scenario identifier, applicable scenario identifier, etc. The following explanation uses the service identifier as an example. That is, when the first information is located within the first uplink NAS message, the service identifier is, for example, located in the header or payload of the first uplink NAS message. For example, if the first uplink NAS message is in plaintext, the first routing network element can parse the payload of the first uplink NAS message even without obtaining the NAS key, thereby obtaining the service identifier.

[0245] Based on the parameters contained in the first information above, the following is an example of the first information containing parameters:

[0246] Example 1: The first piece of information is EPD.

[0247] Example 2: The first piece of information is a combination of EPD and service identifier. The service identifier can be one or more of the following: slice identifier, subnet identifier, and PDU session identifier. For example, the first piece of information is a combination of EPD and slice identifier, where EPD is EPD1 and slice identifier is S-NSSAI 1. Another example is a combination of EPD and PDU session identifier, where EPD is EPD1 and PDU session identifier is PDU session identifier 2. Yet another example is a combination of EPD and subnet identifier, where EPD is EPD1 and subnet identifier is subnet ID 2.

[0248] Example 3: The first piece of information is the message type.

[0249] Example 4: The first piece of information is a combination of message type and service identifier. The service identifier can be one or more of the following: slice identifier, subnet identifier, and PDU session identifier. For example, the first piece of information is a combination of message type and slice identifier; the message type is PDU session establishment request, and the slice identifier is S-NSSAI 1; or, the message type is registration request, and the slice identifier is S-NSSAI 2. Another example: the first piece of information is a combination of message type and subnet identifier; the message type is PDU session establishment request, and the subnet identifier is subnet ID 1; or the message type is registration request, and the subnet identifier is subnet ID 2. Yet another example: the first piece of information is a combination of message type and PDU session identifier; where the message type is PDU session establishment request, and the PDU session identifier is PDU session identifier 1.

[0250] Example 5: The first piece of information is a combination of EPD and message type. For example, the EPD is EPD1, and the message type is PDU session establishment request. Or, the EPD is EPD2, and the message type is registration request.

[0251] Example 6: The first piece of information is a combination of EPD, message type, and service identifier. The service identifier can be one or more of the following: slice identifier, subnet identifier, and PDU session identifier. For example, the first piece of information is a combination of EPD, message type, and slice identifier, where EPD is EPD1, message type is PDU session establishment request, and slice identifier is S-NSSAI 1; or, EPD is EPD2, message type is registration request, and slice identifier is S-NSSAI 2. Another example: the first piece of information is a combination of EPD, message type, and subnet identifier, where EPD is EPD1, message type is PDU session establishment request, and subnet identifier is subnetID 1; or, EPD is EPD2, message type is registration request, and subnet identifier is subnetID 2. Yet another example: the first piece of information is a combination of EPD, message type, and PDU session identifier, where EPD is EPD1, message type is PDU session establishment request, and PDU session identifier is PDU session identifier 1.

[0252] In one possible example, before the terminal sends the first uplink NAS message and the first information, it can be determined that the identifier of the first target network element has not been obtained, and thus it can be determined that the identifier of the first target network element is not included in the first uplink NAS message. That is, the identifier of the first target network element is not included in the first uplink NAS message generated by the terminal (or the first uplink NAS message sent by the terminal).

[0253] The terminal did not obtain the identifier of the first target network element. Specifically, the terminal did not obtain the identifier of the first target network element according to the fourth information.

[0254] The fourth information includes, or specifically includes, one or more of the following: EPD, NAS type, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. For explanations of each parameter, please refer to the above description of the parameters in the first information. The content of the first information and the fourth information may be the same or different. The fourth information can be determined by the terminal based on the first uplink NAS message to be generated (or sent). The main difference between the fourth information and the first information is that the fourth information is used by the terminal before generating the first uplink NAS message to characterize the NAS type, message type, etc., of the first uplink NAS message; the first information is used by the terminal after generating the first uplink NAS message to characterize the NAS type, message type, etc., of the first uplink NAS message.

[0255] It is understandable that before generating the first uplink NAS information, the terminal can determine the identifier of the first target network element that has not been obtained based on the fourth information, and then generate a first uplink NAS message that does not contain the identifier of the first target network element.

[0256] In one specific implementation, the identifier of the first target network element can be a temporary identifier of the first target network element. If the terminal does not obtain the temporary identifier of the first target network element, it can be determined that the temporary identifier of the first target network element is not included in the first uplink NAS message. For example, the header of the first uplink NAS message does not include the temporary identifier of the first target network element.

[0257] In one specific implementation, the first uplink NAS message includes a receiver information field, the value of which indicates the receiver of the first uplink NAS message. If the terminal does not obtain the identifier of the first target network element, the terminal can determine that the receiver information field (or the value of the receiver information field) in the first uplink NAS message is set to empty.

[0258] For example, the receiver information field in the header of the first uplink NAS message is set to empty.

[0259] In this application, the "recipient information field" is a field in the first uplink NAS message used to indicate the target network element. "Recipient information field" is an exemplary name for this field, and it can also be referred to by other names, such as "recipient field," "target network element field," or "target network element information field." The statement "the value of this field is set to empty" can also be replaced with "the field is all 0s (or, as understood, when the field is all 0s, the recipient field is a special field)," or "the recipient information field has other preset values." Furthermore, if the terminal does not obtain the identifier of the first target network element, this field may not be included in the first uplink NAS message.

[0260] For the first routing network element, it can determine whether the received uplink NAS message includes a temporary identifier of the target network element. This target network element is the network element that processes the uplink NAS message. For example, the first routing network element determines whether the uplink NAS message includes a temporary identifier of the target network element based on the value of the receiver field in the uplink NAS message. When the first routing network element determines that the uplink NAS message includes a temporary identifier of the target network element, it can determine the internal identifier of the target network element from the locally stored mapping relationship between temporary identifiers and internal identifiers of the target network element based on the temporary identifier included in the uplink NAS message. Based on the internal identifier of the target network element, it forwards the uplink NAS message to the target network element. Alternatively, the first routing network element can request the internal identifier of the target network element from other routing network elements / NRF network elements based on the temporary identifier of the target network element. When the first routing network element determines that the uplink NAS message does not include a temporary identifier of the target network element, the first routing network element needs to first discover the target network element from the NRF network elements through the network element discovery process before forwarding the uplink NAS message to the target network element.

[0261] In one possible example, the first uplink NAS message sent by the terminal does not include the temporary identifier of the first target network element. Therefore, the first routing network element can determine that it needs to discover the first target network element from the NRF network elements through the network element discovery process (i.e., execute step 702).

[0262] Step 702: The first routing network element obtains the internal identifier and the temporary identifier of the first target network element.

[0263] Step 702 is an optional step.

[0264] In one possible implementation, the first routing network element obtains the internal identifier of the first target network element based on the first information. For example, the first routing network element obtains the internal identifier of the first target network element based on the first information and the network element discovery process, as detailed in steps A to C below:

[0265] Step A: The first routing network element sends a network element discovery request to the NRF network element, and correspondingly, the NRF network element receives the network element discovery request from the first routing network element. The network element discovery request includes second information, which is used to determine the first target network element.

[0266] For example, the second information includes or specifically includes one or more of the following: EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. For a description of each parameter, please refer to the description of each parameter in the first information above.

[0267] For example, the second information is determined based on the first information. For instance, the first routing network element determines the second information based on the first information.

[0268] In the first possible example, the second information is the first information, and the first routing network element can carry the first information in the network element discovery request.

[0269] For example, the first piece of information is EPD. The second piece of information is also EPD.

[0270] Alternatively, the first piece of information is a combination of EPD and service identifier. The second piece of information is also a combination of EPD and service identifier.

[0271] Alternatively, the first piece of information is a combination of message type and service identifier. The second piece of information is also a combination of message type and service identifier.

[0272] Alternatively, the first piece of information is a combination of EPD, message type, and service identifier. The second piece of information is also a combination of EPD, message type, and service identifier.

[0273] In the second possible example, the second information is different from the first information. That is, the first routing network element can process the first information to obtain the second information, and then carry the second information in the network element discovery request.

[0274] For example, the first routing network element can replace the EPD in the first information with the network element type. The first routing network element may have a pre-defined mapping relationship between EPD and network element type, or the protocol may specify the mapping relationship between EPD and network element type.

[0275] For example, if EPD is EPD1, the first routing network element can replace EPD1 with an SMF network element type; or, if EPD is EPD2, the first routing network element can replace EPD2 with an AMF network element type.

[0276] For example, the first routing network element can replace the message type in the first information with the network element type. The first routing network element may have a pre-defined mapping relationship between message types and network element types, or the protocol may specify the mapping relationship between message types and network element types.

[0277] For example, if the message type is a PDU session establishment request, the first routing network element can replace the PDU session establishment request with an SMF network element type; or, if the message type is a registration request, the first routing network element can replace the registration request with an AMF network element type.

[0278] Optionally, the network element discovery request can be used not only by the NRF network element to determine the first target network element, but also to instruct the NRF network element to generate a temporary identifier for the first target network element.

[0279] The temporary identifier of the first target network element is understood to be an identifier assigned to the terminal from a core network security perspective to prevent the internal identifier of the first target network element from being exposed to the terminal. In other words, the temporary identifier of the first target network element is an identifier used to temporarily identify the first target network element. The temporary identifier of the first target network element can be used by network element consumers to index / identify the first target network element. It can be understood that when the first target network element does not want to expose its permanent identifier, it can use a temporary identifier as its identifier. The first target network element can have one or more temporary identifiers. For example, when the network element consumer is a network entity (e.g., a terminal) outside the 3GPP management domain or core network, the temporary identifier of the first target network element can be used by the terminal to index / identify the first target network element. The network element consumer can obtain multiple different identifiers corresponding to the first target network element at different times. Furthermore, the network element consumer cannot determine or directly determine whether the multiple temporary identifiers it obtains correspond to the same network element.

[0280] For example, the network element discovery request may also carry third information, which may include one or more of the following: NAS type (values ​​may be session management type, mobility management type, awareness management type, etc.), NAS message type (values ​​may be PDU session establishment request, PDU session modification request, PDU session release request, registration request, service request, etc.), indication of generating a temporary identifier for the first target network element, indication of the existence of downlink NAS messages in the network, indication of the existence of other uplink NAS messages in the network, first field, consumer field, and service name field. The consumer field is valued as "identifier of the first routing network element"; the service name field is valued as "service that forwards NAS messages"; and the first field is valued as "NAS message type".

[0281] The NAS type can also be replaced with EPD, and the corresponding values ​​can be EPD1, EPD2 or EPD3.

[0282] For example, the third information can be used to instruct an NRF network element to generate a temporary identifier for a first target network element. For example, when an NRF network element determines that the network element discovery request carries third information, it generates a temporary identifier for the first target network element.

[0283] The "instruction to generate a temporary identifier for the first target network element" can be considered a visible instruction in the network element discovery request. When this instruction exists, the NRF network element can generate a temporary identifier for the discovered network element (i.e., the first target network element) based on this instruction. For example, this instruction can indicate whether the NRF should return the temporary identifier of the first target network element, or request the NRF to return the temporary identifier of the first target network element. For instance, the instruction can be a Boolean type, where a value of True indicates that the NRF should return the temporary identifier of the first target network element, and a value of False indicates that the NRF does not need to return the temporary identifier of the first target network element. When this instruction is absent or omitted, it indicates that the NRF does not need to return the temporary identifier of the first target network element.

[0284] The following parameters can be considered implicit indications in the network element discovery request: “NAS type”, “NAS message message type”, “indication that downlink NAS messages exist in the network”, “indication that other uplink NAS messages exist in the network”, “consumer field value is “identifier of the first routing network element””, “service name field value is “service that forwards NAS messages”, and “first field value is “NAS message type””. When the NRF network element sees this information in the network element discovery request, it can determine that there are other uplink NAS messages sent to the first target network element by the terminal. Then the NRF network element can generate a temporary identifier for the first target network element.

[0285] Step B: The NRF network element determines the first target network element based on the second information in the network element discovery request.

[0286] Specifically, the NRF network element determines the internal identifier of the first target network element based on the second information in the network element discovery request.

[0287] In one possible implementation, multiple network elements register their respective configuration files with the NRF network element. That is, the NRF network element includes configuration files for multiple network elements. Each network element's configuration file includes, but is not limited to, one or more of the following: the network element's instance ID (NF Instance ID), network element type, subnet identifier, list of S-NSSAIs supported by the network element, the network element's IP address, the network element's port number, and the network element's geographical location information. Based on this second information and the configuration files of the multiple network elements, the NRF network element can determine a first target network element from among the multiple network elements, and then determine the internal identifier of the first target network element. For example, the network element's configuration file may also include a temporary identifier for the network element; that is, the network element generates its own temporary identifier. For instance, the configuration file of an AMF network element includes a temporary identifier for the AMF network element.

[0288] The internal identifier of the first target network element can be considered as an identifier that uniquely identifies the first target network element within a 3GPP management domain (e.g., within a PLMN). It can be understood that this internal identifier is information within the core network and is not disclosed to terminals. Examples of internal identifiers for the first target network element include its instance identifier (NF Instance ID) and IP address. The internal identifier of the first target network element can also be referred to as the PLMN internal identifier or simply the network identifier.

[0289] For example, when a network element discovery request is used to instruct an NRF network element to generate a temporary identifier for a first target network element, the NRF network element may generate the temporary identifier for the first target network element after determining the first target network element, or before determining the first target network element. As another example, the NRF network element may generate the temporary identifier for the first target network element after receiving the network element discovery request, or before receiving the network element discovery request. As yet another example, after the first target network element sends a network element registration request to the NRF network element, the NRF network element generates the temporary identifier for the first target network element.

[0290] It is understood that in this application, "NRF network element generates temporary identifier" can also be replaced with "NRF network element determines temporary identifier".

[0291] For example, the temporary identifier of the first target network element may include one or more of the following: the identifier of the first routing network element, information used to uniquely identify the first target network element on the first routing network element, the identifier of the NRF network element, information used to uniquely identify the first target network element on the NRF network element, the identifier of the first target network element, and information used to uniquely identify the first target network element on the first target network element. It can be understood that the first routing network element is a network element that stores the mapping relationship between the temporary identifier and the internal identifier of the first target network element (for example, the first routing network element is used to route a second uplink NAS message, and the target network element of the second uplink NAS message is the first target network element; or, for example, the first routing network element is used to provide the mapping relationship); the NRF network element is a network element used to discover the first target network element in the network element discovery process; furthermore, the NRF network element may also be a network element that stores the mapping relationship between the temporary identifier and the internal identifier of the first target network element (for example, it may also be a network element that provides the mapping relationship).

[0292] The identifier of the first routing network element is a globally unique identifier used to identify the first routing network element. The identifier of the first routing network element may include one or more of the following: the region ID of the first routing network element, the set ID of the first routing network element, and the pointer of the first routing network element. The region ID identifies the region, the set ID uniquely identifies the set within the region, and the pointer identifies one or more routing network elements within the set. The region ID of the first routing network element allows operators to reuse the same set ID and pointer for different regions. Operators need to ensure that the combination of the set ID and pointer is unique within the region of the routing network element, and also unique within the regions of overlapping routing network elements. Furthermore, the identifier of the first routing network element also includes MCC and MNC, where MCC and MNC constitute the PLMN identifier, which can be used to represent the identifier of the PLMN where the first routing network element is located or the identifier of the PLMN to which the terminal is accessed. Furthermore, the identifiers of the MCC, MNC, and the first routing element constitute a globally unique routing element identifier.

[0293] The NRF element identifier is a globally unique identifier used to identify an NRF element. An NRF element identifier can consist of one or more of the following: an NRF element region identifier, an NRF element set identifier, or an NRF element pointer. The region identifier identifies the region, the set identifier uniquely identifies a set within that region, and the pointer identifies one or more NRF elements within that set. The region identifier allows operators to reuse the same set identifier and pointer across different regions. Operators must ensure that the combination of the NRF element set identifier and pointer is unique within the NRF element's region, and also unique within the overlapping regions if overlapping NRF element regions are used. Furthermore, the NRF element identifier also includes the MCC and MNC, which constitute the PLMN identifier and can be used to represent the PLMN where the NRF element resides or the PLMN to which the terminal is accessed. Finally, the MCC, MNC, and NRF element identifier together constitute a globally unique NRF element identifier.

[0294] The identifier of the first target network element is distinct from either a temporary identifier (e.g., composed of the identifier of the first target network element and information used to uniquely identify the first target network element) or an internal identifier of the first target network element (e.g., the instanceID of the first target network element). The identifier of the first target network element is a globally unique identifier used to identify the first target network element. The identifier of the first target network element may include one or more of the following: a region identifier of the first target network element, a set identifier of the first target network element, and a pointer to the first target network element. The region identifier of the first target network element is used to identify a region, the set identifier of the first target network element is used to uniquely identify a set within the region, and the pointer to the first target network element is used to identify one or more target network elements within the set. The region identifier of the first target network element allows the operator to reuse the same set identifier and pointer of the target network element in different regions. The operator needs to ensure that the combination of the set identifier and pointer of the target network element is unique within the region of the target network element, and that if overlapping regions of target network elements are used, it is also unique within the overlapping regions of the target network elements. In addition, the identifier of the first target network element also includes MCC and MNC. MCC and MNC constitute the PLMN identifier, which can be used to represent the identifier of the PLMN where the first target network element is located or the identifier of the PLMN to which the terminal is connected. MCC, MNC and the identifier of the first target network element constitute a globally unique target network element identifier.

[0295] It is understandable that the area identifier of the first routing network element, the set identifier of the first routing network element, the pointer of the first routing network element, the area identifier of the NRF network element, the set identifier of the NRF, the pointer of the NRF, the area identifier of the first target network element, the set identifier of the first target network element, the pointer of the first target network element, the MCC and MNC can be exposed to the terminal without affecting the security of the core network.

[0296] In the first possible example, the temporary identifier of the first target network element is a combination of the identifier of the first routing network element and information on the first routing network element used to uniquely identify the first target network element. Furthermore, the identifier of the first routing network element can be composed of the area identifier of the first routing network element, the set identifier of the first routing network element, and a pointer to the first routing network element. For example, the temporary identifier of the first target network element is generated by the first routing network element.

[0297] In the second possible example, the temporary identifier of the first target network element is a combination of the identifier of the NRF network element and information used to uniquely identify the first target network element on the NRF network element. Furthermore, the identifier of the NRF network element can be composed of the region identifier of the NRF network element, the set identifier of the NRF network element, or a pointer to the NRF network element. For example, the temporary identifier of the first target network element is generated by the NRF network element.

[0298] In a third possible example, the temporary identifier of the first target network element is a combination of the identifier of the first target network element and information used to uniquely identify the first target network element. Furthermore, the identifier of the first target network element can be composed of a region identifier, a set identifier, or a pointer to the first target network element. For example, the temporary identifier of the first target network element is generated by the first target network element itself.

[0299] In the fourth possible example, the temporary identifier of the first target network element is a combination of the identifier of the first routing network element, the identifier of the NRF network element, and information on the NRF network element used to uniquely identify the first target network element. Further, the identifier of the first routing network element can be composed of the area identifier of the first routing network element, the set identifier of the first routing network element, and a pointer to the first routing network element; similarly, the identifier of the NRF network element can be composed of the area identifier of the NRF network element, the set identifier of the NRF network element, and a pointer to the NRF network element. Here, it can be considered that the identifier of the NRF network element is used to characterize the generator of the temporary identifier of the first target network element, and the identifier of the first routing network element is used to characterize the user of the temporary identifier of the first target network element. In other words, the temporary identifier of the first target network element is generated by the NRF network element and used by the first routing network element.

[0300] In addition, the temporary identifier of the first target network element may also include second information.

[0301] The temporary identifier of the first target network element can be used for the forwarding of subsequent uplink NAS messages, as described in the following embodiments.

[0302] In step C, the NRF network element sends a network element discovery response to the first routing network element, and correspondingly, the first routing network element receives the network element discovery response from the NRF network element. The network element discovery response includes the internal identifier of the first target network element. For example, when the NRF network element also generates a temporary identifier for the first target network element, the network element discovery response may also include the temporary identifier of the first target network element.

[0303] In one possible implementation, the network element discovery response includes a profile of the first target network element, which includes its internal identifier. Alternatively, the first target network element's profile includes both its internal identifier and a temporary identifier. For example, the temporary identifier can be generated by the NRF network element; or it can be generated by the first target network element and carried in its profile, thus being obtained by the NRF network element. For example, the first target network element's profile may also include its fully qualified domain name (FQDN). The FQDN is a fully qualified domain name used to precisely identify the location of the first target network element in the network. For example, the FQDN may include one or more of the following: top-level domain (TLD), second-level domain (SLD), subdomain, hostname, and root domain.

[0304] It is understandable that before the NRF network element sends a network element discovery response to the first routing network element, the first target network element sends a network element registration request to the NRF network element. The network element registration request includes the profile of the first target network element. The NRF network element can send a network element discovery response to the first routing network element based on the profile of the first target network element included in the network element registration request. Furthermore, the profile of the first target network element carried in the network element discovery response can be all or part of the profile of the first target network element carried in the network element registration request.

[0305] For example, the internal identifier of the first target network element can be used by the first routing network element to determine the profile of the first target network element, and send a first uplink NAS message to the first target network element according to the profile of the first target network element (e.g., the FQDN of the first target network element).

[0306] In this application, the English term for NF discovery request can be expressed as "NF discovery request," and the English term for NF discovery response can be expressed as "NF discovery request response." Both the NF discovery request and the NF discovery response are service-based interface (SBI) messages. In this application, the NF discovery request can also be replaced by a receiver request message, and the NF discovery response can also be replaced by a receiver response message. In this case, it can be considered that the first routing NF element can also request the internal identifier of the first target NF element through other procedures.

[0307] In another possible implementation, the first routing network element may discover the first target network element without going through the network element discovery process. Instead, it may forward the first information and information from the first uplink NAS message (e.g., all or part of the NAS message) to the NRF network element to request the internal identifier of the first target network element. Optionally, it may also request the temporary identifier of the first target network element. For example, when the first information is outside the first uplink NAS message, the first routing network element may forward the first information and information from the first uplink NAS message to the NRF network element. As another example, when the first information is inside the first uplink NAS message, the first routing network element forwards the information from the first uplink NAS message to the NRF network element, and the forwarded information includes the first information. For example, the information forwarded by the first routing network element to the NRF network element is contained in an SBI message. The NRF network element determines the first target network element based on the first information and sends the profile of the first target network element to the first routing network element. The profile of the first target network element includes the internal identifier of the first target network element. Optionally, the profile of the first target network element may also include the temporary identifier of the first target network element.

[0308] Furthermore, in another possible example, when the network element discovery request is also used to request a temporary identifier of the first target network element (e.g., the network element discovery request includes third information), or when the first routing network element also forwards information from the first uplink NAS message to the NRF network element, the profile of the first target network element sent by the NRF network element to the first routing network element may include a temporary identifier of the first target network element. For example, the profile of the first target network element may not include an internal identifier of the first target network element. The temporary identifier of the first target network element is used by the first routing network element to determine the profile of the first target network element and then send the first uplink NAS message. See [link to relevant documentation] for details. Figure 14 The description in the relevant embodiments.

[0309] For example, the NRF network element sends the internal identifier of the first target network element to the first routing network element. Specifically, this could be sending the profile of the first target network element to the first routing network element, where the profile of the first target network element includes the internal identifier of the first target network element. For instance, after determining the first target network element, the NRF network element sends the profile of the first target network element to the first routing network element, where the profile of the first target network element includes the internal identifier of the first target network element. For example, the profile of the first target network element may include both the internal identifier of the first target network element and a temporary identifier of the first target network element.

[0310] For another example, after receiving the internal identifier of the first target network element from the NRF network element, the first routing network element requests the profile of the first target network element from the NRF network element based on the internal identifier of the first target network element.

[0311] For another example, after receiving the temporary identifier of the first target network element from the NRF network element, the first routing network element requests the profile of the first target network element from the NRF network element based on the temporary identifier of the first target network element.

[0312] It should be added that the network element discovery response may not include the temporary identifier of the first target network element. For example, the NRF network element may send the temporary identifier of the first target network element and the network element discovery response as two separate messages, and the order of these two messages is not limited.

[0313] For example, the NRF network element may not generate a temporary identifier for the first target network element. Exemplarily, the first routing network element generates a temporary identifier for the first target network element after receiving a network element discovery response, or before receiving such a response. It is understood that in this application, "the first routing network element generates a temporary identifier" can also be replaced with "the first routing network element determines a temporary identifier."

[0314] For example, the temporary identifier of the first target network element may include one or more of the following: an identifier of the first routing network element, and information on the first routing network element used to uniquely identify the first target network element. For instance, the temporary identifier of the first target network element is a combination of the identifier of the first routing network element and the information on the first routing network element used to uniquely identify the first target network element. Further, the identifier of the first routing network element may be one or more of the following: a region identifier of the first routing network element, a set identifier of the first routing network element, and a pointer to the first routing network element.

[0315] In addition, the temporary identifier of the first target network element may also include first information or second information.

[0316] In other words, when the first routing network element obtains the internal identifier and the temporary identifier of the first target network element, it can do so in the following ways:

[0317] Example a: The first routing network element obtains the internal identifier and temporary identifier of the first target network element from the network element discovery response.

[0318] Example b: The first routing network element obtains the internal identifier of the first target network element from the network element discovery response, and the first routing network element generates a temporary identifier for the first target network element.

[0319] Example c: The first routing network element obtains the internal identifier of the first target network element from the network element discovery response, and the first routing network element also receives the temporary identifier of the first target network element from the NRF network element.

[0320] In Examples b and c, the order in which the first routing network element obtains the internal identifier of the first target network element and the temporary identifier of the first target network element is not restricted.

[0321] Optionally, the first routing network element may also store the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element. Alternatively, the NRF network element may store the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element. When the first routing network element needs to obtain the internal identifier of the first target network element again, it can request it from the NRF network element based on the temporary identifier of the first target network element. Here, the temporary identifier of the first target network element may originate from the terminal, as described in the following embodiments.

[0322] Step 703: The first routing network element sends a first uplink NAS message to the first target network element based on the internal identifier of the first target network element. Correspondingly, the first target network element receives the first uplink NAS message from the first routing network element.

[0323] In a specific example, a first routing network element sends a first message to a first target network element, and correspondingly, the first target network element receives the first message from the first routing network element. The first message includes a first uplink NAS message, for example, a first SBI message. Exemplarily, the first routing network element may also send a temporary identifier of the first target network element to the first target network element.

[0324] In a specific example, the first routing network element sends a first uplink NAS message to the first target network element based on the internal identifier of the first target network element. Specifically, the first routing network element determines the profile of the first target network element based on its internal identifier, and then sends the first uplink NAS message to the first target network element based on that profile. For example, the first routing network element sends the first uplink NAS message to the first target network element based on the FQDN in the first target network element's profile.

[0325] Step 704: The first target network element sends a first downlink NAS message to the first routing network element; correspondingly, the first routing network element receives the first downlink NAS message from the first target network element. For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0326] In a specific example, a first target network element sends a second message to a first routing network element, and the first routing network element receives the second message from the first target network element. The second message is a response message to the first message. Optionally, the second message includes a first downlink NAS message; for example, the second message is a second SBI message.

[0327] For example, the first downlink NAS message includes a sender information field, which contains information about the sender of the first downlink NAS message. For instance, the value of the sender information field is the internal identifier of the first target network element; or, for example, when the first routing network element sends a temporary identifier of the first target network element to the first target network element, the value of the sender information field is the temporary identifier of the first target network element.

[0328] The following are four examples of the first target network element sending the first downlink NAS message to the first routing network element:

[0329] Example A: Considering the integrity protection and encryption of NAS messages, when the first routing network element sends the temporary identifier of the first target network element to the first target network element, after the first target network element sets the value of the sender information field to the temporary identifier of the first target network element, it can perform integrity protection and encryption on the first downlink NAS message (including the sender information field) to obtain the first downlink NAS message after integrity protection and encryption, and send the first downlink NAS message after integrity protection and encryption to the first routing network element.

[0330] Example B: Considering the integrity protection and encryption of NAS messages, after setting the value of the sender information field to the internal identifier of the first target network element, the first target network element performs integrity protection and encryption on the first downlink NAS message (excluding the sender information field) to obtain the integrity-protected and encrypted first downlink NAS message, and sends the integrity-protected and encrypted first downlink NAS message to the first routing network element.

[0331] Example C: The first target network element sends a first downlink NAS message and its internal identifier to the first routing network element. That is, the internal identifier of the first target network element is located outside the first downlink NAS message. For example, the sender information field in the first downlink NAS message is empty. Another example is that both the first downlink NAS message and the internal identifier of the first target network element are included in the second SBI message.

[0332] Example D: The first target network element sends a first downlink NAS message and a temporary identifier of the first target network element to the first routing network element. That is, the temporary identifier of the first target network element is located outside the first downlink NAS message. For example, the sender information field in the first downlink NAS message is empty. Another example is that both the first downlink NAS message and the temporary identifier of the first target network element are included in the second SBI message.

[0333] For example, the first target network element executes the corresponding processing logic based on the first uplink NAS message, and then sends the first downlink NAS message to the first routing network element. The following example provides an example of the first uplink NAS message, the first target network element, and the first downlink NAS message:

[0334] When the first uplink NAS message is a PDU session establishment request message, the first target network element is an SMF network element, and the first downlink NAS message is a PDU session establishment accept message or a PDU session establishment reject message. Alternatively,

[0335] When the first uplink NAS message is a PDU session modification request message, the first target network element is an SMF network element, and the first downlink NAS message is a PDU session modification accept message or a PDU session modification reject message.

[0336] When the first uplink NAS message is a PDU session release request message, the first target network element is an SMF network element, and the first downlink NAS message is a PDU session release command message or a PDU session release complete message.

[0337] When the first uplink NAS message is a registration request message, the first target network element is the AMF network element, and the first downlink NAS message is a registration accept message or a registration reject message.

[0338] When the first uplink NAS message is a service request message, the first target network element is the AMF network element, and the first downlink NAS message is a service accept message or a service reject message.

[0339] When the first uplink NAS message is a registration request message, the first target network element is the AMF network element, and the first downlink NAS message is a registration accept message.

[0340] Step 705: The first routing network element sends a first downlink NAS message and a temporary identifier of the first target network element to the terminal. Correspondingly, the terminal receives the first downlink NAS message and the temporary identifier of the first target network element.

[0341] For example, if the first routing network element determines that there are still uplink NAS messages between the terminal and the first target network element, it can send a temporary identifier of the first target network element to the terminal. For instance, after obtaining the temporary identifier of the first target network element from the network element discovery response, the first routing network element can determine that there are still uplink NAS messages between the terminal and the first target network element, and then send the temporary identifier of the first target network element to the terminal; or, if the first routing network element determines that there are still uplink NAS messages between the terminal and the first target network element, it can generate a temporary identifier of the first target network element and send the temporary identifier of the first target network element to the terminal.

[0342] In other words, if there are no more uplink NAS messages between the terminal and the first target network element, the first routing network element may not send the temporary identifier of the first target network element to the terminal even if it obtains the temporary identifier of the first target network element from the network element discovery response; or, for example, the first routing network element does not need to generate the temporary identifier of the first target network element.

[0343] For example, the first routing network element can determine, based on pre-configuration information or protocol provisions, whether there are other uplink NAS messages sent by the terminal to the first target network element after the first uplink NAS message.

[0344] For example, in the first uplink NAS message, which is a registration request message, the first target network element is specifically the AMF network element, and the first routing network element can obtain the temporary identifier of the AMF network element. Based on the protocol, the first routing network element determines that after the terminal sends the registration request message to the AMF network element, it also needs to send a service request message to the AMF network element. Therefore, the first routing network element can send the temporary identifier of the AMF network element to the terminal.

[0345] In Example B above, after receiving the first downlink NAS message from the first target network element, the first routing network element can replace the value of the sender information field in the first downlink NAS message from "the internal identifier of the first target network element" to "the temporary identifier of the first target network element". In Example C above, after receiving the first downlink NAS message and the internal identifier of the first target network element, the first routing network element can also replace the internal identifier of the first target network element with the temporary identifier of the first target network element. For example, in Example C or Example D above, the first routing network element can also perform integrity protection and encryption on the first downlink NAS message and the temporary identifier of the first target network element.

[0346] Alternatively, the temporary identifier of the first target network element can be located outside the first downlink NAS message. The first downlink NAS message and the temporary identifier of the first target network element can be sent not only through the same message but also through two separate messages, and the order of these two messages is not limited. The temporary identifier of the first target network element can also be located inside the first downlink NAS message. For example, the temporary identifier of the first target network element is located in the header of the first downlink NAS message. It can be understood that both methods can be considered as the first routing network element sending the first downlink NAS message and the temporary identifier of the first target network element to the terminal. In a possible example, the first routing network element sends an N2 message to the RAN, which carries the first downlink NAS message and the temporary identifier of the first target network element; the RAN then sends a downlink RRC message to the terminal, which carries the first downlink NAS message and the temporary identifier of the first target network element.

[0347] For the terminal, it can also store the mapping relationship between the first information and the temporary identifier of the first target network element. For example, if the first information is EPD1, the terminal stores the mapping relationship "EPD1 and the temporary identifier of the first target network element"; or if the first information is a combination of EPD and slice identifier, where EPD is EPD1 and slice identifier is S-NSSAI 1, the terminal stores the mapping relationship "EPD1, S-NSSAI 1 and the temporary identifier of the first target network element"; or if the first information is a combination of message type and slice identifier, where the message type is PDU session establishment request and slice identifier is S-NSSAI 1, the terminal stores the mapping relationship "PDU session establishment request, S-NSSAI 1 and the temporary identifier of the first target network element".

[0348] Alternatively, the terminal may also store the mapping relationship between the fifth piece of information and the temporary identifier of the first target network element. The fifth piece of information and the first piece of information are associated.

[0349] For example, the first information is the message type, and the fifth information is the EPD corresponding to the message type; for example, the message type is PDU session establishment request, the PDU session establishment request corresponds to EPD1, and the terminal saves the mapping relationship "EPD1 and the temporary identifier of the first target network element".

[0350] For example, the first information is a combination of message type and service identifier, and the fifth information is a combination of EPD and service identifier corresponding to the message type. For instance, the first information is a combination of message type and slice identifier, the message type is PDU session establishment request, the PDU session establishment request corresponds to EPD1, the slice identifier is S-NSSAI 1, and the terminal stores the mapping relationship "EPD1, S-NSSAI 1 and temporary identifier of the first target network element".

[0351] For example, the first information is a combination of message type and service identifier, and the fifth information is a combination of network element type and service identifier corresponding to the message type. For instance, the first information is a combination of message type and slice identifier, the message type is PDU session establishment request, the PDU session establishment request corresponds to SMF network element type, the slice identifier is S-NSSAI 1, and the terminal stores the mapping relationship "SMF network element type, S-NSSAI 1 and temporary identifier of the first target network element".

[0352] For ease of description, the following explanation will use the mapping relationship between the terminal storing the first information and the temporary identifier of the first target network element as an example.

[0353] Subsequently, before sending the second uplink NAS message, the terminal can determine the fourth information corresponding to the second uplink NAS message based on the message to be sent. Based on the mapping relationship between the fourth information, the stored first information, and the temporary identifier of the first target network element, the terminal determines the temporary identifier of the first target network element and carries this temporary identifier in the second uplink NAS message. The fourth information includes, or specifically includes, one or more of the following: EPD, NAS type, message type, network element type, slice identifier, subnet identifier, and PDU session identifier.

[0354] It is understandable that the second uplink NAS message is another uplink NAS message sent by the terminal to the first target network element, and the second uplink NAS message is located after the first uplink NAS message.

[0355] For example, the fourth information corresponding to the second uplink NAS message is the same as the fourth information corresponding to the first uplink NAS message.

[0356] For example, when the first piece of information is an EPD, the first uplink NAS message and the second uplink NAS message correspond to the same EPD, such as both being EPD1, meaning they are both session management type. Alternatively, when the fourth piece of information is a combination of an EPD and a service identifier, the first uplink NAS message and the second uplink NAS message correspond to the same EPD and service identifier, such as both being EPD1 and S-NSSAI 1, meaning they are both session management type and both need to be routed to an SMF network element that supports S-NSSAI 1. Another example is that the first uplink NAS message and the second uplink NAS message are two consecutive uplink NAS messages in the same process, such as a registration process or a PDU session establishment process.

[0357] For example, the terminal carries the temporary identifier of the first target network element in the header of the second uplink NAS message. For example, the first routing network element can receive the second uplink NAS message, obtain the temporary identifier of the first target network element from the header of the second uplink NAS message, and then obtain the internal identifier of the first target network element based on the temporary identifier, and then forward the second uplink NAS message to the first target network element. The first routing network element does not need to parse the payload of the second uplink NAS message. For example, the second uplink NAS message can be ciphertext.

[0358] Understandably, the terminal can determine whether it can obtain the temporary identifier of the target network element corresponding to the fourth information based on its stored mapping relationship and the fourth information of the uplink NAS message to be sent.

[0359] For example, as shown in Table 1, if the uplink NAS message to be sent by the terminal is a session management message (corresponding to EPD1) and the service type requires network element support for S-NSSAI 1, then the terminal can determine the temporary identifier of SMF network element 1 based on this fourth information (EPD1, S-NSSAI 1) and carry the temporary identifier of SMF network element 1 in the uplink NAS message. As another example, if the uplink NAS message to be sent by the terminal is a mobility management message (corresponding to EPD2) and the service type requires network element support for S-NSSAI 1, then the terminal can determine the temporary identifier of AMF network element 1 based on this fourth information (EPD2, S-NSSAI 1) and carry the temporary identifier of AMF network element 1 in the uplink NAS message. And as yet another example, if the uplink NAS message to be sent by the terminal is a mobility management message (corresponding to EPD2) and the service type requires network element support for S-NSSAI 3, then the terminal can determine the temporary identifier of AMF network element 1 based on this fourth information (EPD2, S-NSSAI 1). 3) If it is determined that the temporary identifier of the target network element cannot be obtained, it is determined that the temporary identifier of the target network element is not included in the uplink NAS message. For example, the value of the receiver information field in the uplink NAS message is set to empty.

[0360] Table 1

[0361] EPD1, S-NSSAI 1 Temporary identifier for SMF network element 1 EPD1, S-NSSAI 2 Temporary identifier for SMF network element 2 EPD2, S-NSSAI 1 Temporary identifier for AMF network element 1 EPD2, S-NSSAI 2 AMF Network Element 2 Temporary Identifier

[0362] The following example illustrates how a first routing network element obtains the internal identifier of the first target network element based on the temporary identifier of the first target network element after receiving a second uplink NAS message:

[0363] Method 1: The first routing network element stores the mapping relationship between the internal identifier and the temporary identifier of the first target network element. The first routing network element can determine the internal identifier of the first target network element based on the temporary identifier of the first target network element and the mapping relationship between the internal identifier and the temporary identifier of the first target network element stored in the first routing network element.

[0364] Method 2: The NRF network element stores a mapping relationship between the internal identifier and temporary identifier of the first target network element. The first routing network element can send a retrieval request to the NRF network element, including the temporary identifier of the first target network element. The NRF network element receives the retrieval request and, based on the temporary identifier of the first target network element in the retrieval request and the mapping relationship between the internal identifier and temporary identifier of the first target network element stored in the NRF network element, determines the internal identifier of the first target network element. The NRF network element then sends the internal identifier of the first target network element to the first routing network element. In this method, the first routing network element does not store a mapping relationship between the internal identifier and temporary identifier of the first target network element.

[0365] For example, after receiving the acquisition request, the NRF network element can also send the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element to the first routing network element according to the temporary identifier of the first target network element in the acquisition request. Thus, after the first routing network element receives the uplink NAS message, it can also determine the internal identifier of the first target network element according to the temporary identifier of the first target network element in the uplink NAS message and the saved mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element.

[0366] It should be added that the second uplink NAS message sent by the terminal can be received not only by the first routing network element but also by other routing network elements (denoted as the second routing network element). At this time, the second routing network element does not store the mapping relationship between the internal identifier and the temporary identifier of the first target network element. The second routing network element can determine which device / network element to request the internal identifier of the first target network element from based on the information carried in the temporary identifier of the first target network element.

[0367] Example (1): The temporary identifier of the first target network element includes the identifier of the first routing network element.

[0368] For example, the temporary identifier of the first target network element also includes information used to uniquely identify the first target network element on the first routing network element.

[0369] After the second routing network element obtains the temporary identifier of the first target network element from the second uplink NAS message, for example, after determining that there is no mapping relationship between the internal identifier and the temporary identifier of the first target network element stored locally, it can proceed in the following three ways:

[0370] Method a: The second routing network element obtains the identifier of the first routing network element from the temporary identifier of the first target network element, and forwards the second uplink NAS message to the first routing network element according to the identifier of the first routing network element. The first routing network element receives the second uplink NAS message from the second routing network element (or, from the terminal and forwarded by the second routing network element), determines the internal identifier of the first target network element according to the temporary identifier in the second uplink NAS message, and the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element stored in the first routing network element, and sends the second uplink NAS message to the first target network element.

[0371] Specifically, when the second routing network element forwards the second uplink NAS message to the first routing network element based on the first routing network element's identifier, it can do so by requesting the first routing network element's profile from the NRF network element based on the first routing network element's identifier, and then forwarding the second uplink NAS message to the first routing network element based on the first routing network element's profile. It is understandable that when the second routing network element subsequently sends other information to the first routing network element based on the first routing network element's identifier, it can also do so by requesting the first routing network element's profile from the NRF network element, and then sending other information to the first routing network element based on the first routing network element's profile; this will not be elaborated further. Furthermore, the method by which the first routing network element sends information to the third routing network element is similar to the method by which the second routing network element sends information to the first routing network element; this will not be elaborated further.

[0372] Method b: The second routing network element obtains the identifier of the first routing network element from the temporary identifier of the first target network element. Based on the identifier of the first routing network element, it sends a first request to the first routing network element. The first request is used to request the internal identifier of the first target network element. For example, the first request includes the temporary identifier of the first target network element. The first routing network element receives the first request from the second routing network element, determines the internal identifier of the first target network element based on the temporary identifier of the first target network element included in the first request, and the mapping relationship between the internal identifier and the temporary identifier of the first target network element, and sends the internal identifier of the first target network element to the second routing network element. The second routing network element then sends a second uplink NAS message to the first target network element based on the internal identifier of the first target network element.

[0373] For example, when the second routing network element sends a second uplink NAS message to the first target network element based on the internal identifier of the first target network element, it can specifically be that the second routing network element requests the profile of the first target network element from the NRF network element based on the internal identifier of the first target network element, and then sends the second uplink NAS message to the first target network element based on the requested profile of the first target network element (e.g., the FQDN of the first target network element).

[0374] For example, when the first routing network element sends the internal identifier of the first target network element to the second routing network element, it can specifically send the profile of the first target network element to the second routing network element. The profile of the first target network element carries the internal identifier of the first target network element. The second routing network element can then send a second uplink NAS message to the first target network element based on the profile of the first target network element (e.g., the FQDN of the first target network element).

[0375] Method c: The second routing network element obtains the identifier of the first routing network element from the temporary identifier of the first target network element. Based on the identifier of the first routing network element, it sends a first request to the first routing network element. The first request is used to request the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element. For example, the first request includes the temporary identifier of the first target network element. Based on the temporary identifier of the first target network element included in the first request, the first routing network element sends the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element to the second routing network element. The second routing network element then sends a second uplink NAS message to the first target network element based on the requested mapping relationship. Here, the first request can also be considered as the second routing network element requesting the internal identifier of the first target network element.

[0376] For example, when the second routing network element sends a second uplink NAS message to the first target network element based on the requested mapping relationship, the second routing network element may request the profile of the first target network element from the NRF network element based on the internal identifier of the first target network element in the mapping relationship, and then send the second uplink NAS message to the first target network element based on the requested profile of the first target network element (e.g., the FQDN of the first target network element).

[0377] For example, when the first routing network element sends this mapping relationship to the second routing network element, it can specifically send the profile of the first target network element to the second routing network element. The profile of the first target network element carries the mapping relationship, or in other words, it carries the internal identifier and temporary identifier of the first target network element. Correspondingly, the second routing network element can send a second uplink NAS message to the first target network element based on the profile of the first target network element (e.g., the FQDN of the first target network element).

[0378] Method d: The second routing network element sends a network element discovery request to the NRF network element (different from the network element discovery request in step 702; this network element discovery request can be referred to as network element discovery request 1). Network element discovery request 1 includes a temporary identifier of the first target network element. The NRF network element can send the internal identifier of the first target network element to the second routing network element based on the temporary identifier of the first target network element in network element discovery request 1. The second routing network element sends a second uplink NAS message to the first target network element based on the internal identifier of the first target network element.

[0379] It is understandable that the second routing network element can perform a network element discovery process based on the temporary identifier of the first target network element to discover the internal identifier of the first target network element. Here, the NRF network element includes a mapping relationship between the temporary identifier and the internal identifier of the first target network element. The temporary identifier of the first target network element can be generated by the NRF network element, or generated by the first target network element and sent to the NRF network element.

[0380] For example, the NRF network element sends the profile of the first target network element to the second routing network element. The profile of the first target network element includes the internal identifier of the first target network element. For example, the first target network element then sends a second uplink NAS message to the first target network element based on its profile (e.g., the FQDN of the first target network element).

[0381] The second routing network element is pre-configured with information about the NRF network element (e.g., the FQDN of the NRF network element), which can be used by the second routing network element to send a network element discovery request 1 to the NRF network element.

[0382] In example (2), the temporary identifier of the first target network element includes the identifier of the NRF network element. For example, the temporary identifier of the first target network element also includes information used to uniquely identify the first target network element on the NRF network element. The specific implementation is similar to method b, method c, or method d in example (1), and the above "first routing network element" can be understood by replacing "NRF network element". Alternatively,

[0383] The temporary identifier of the first target network element includes the identifier of the first target network element. For example, the temporary identifier of the first target network element also includes information used to uniquely identify the first target network element. The specific implementation is similar to method b, method c or method d in example (1), and the above "first routing network element" can be replaced with "first target network element" for understanding.

[0384] Example (3) shows that the temporary identifier of the first target network element includes the identifier of the first routing network element, the identifier of the NRF network element, and information on the NRF network element used to uniquely identify the first target network element. The specific implementation is similar to that in Example (1).

[0385] Example (4): The temporary identifier of the first target network element includes the identifier of the first target network element. For example, the temporary identifier of the first target network element also includes information used to uniquely identify the first target network element.

[0386] The second routing network element sends a network element discovery request (different from the network element discovery request in step 702, this network element discovery request can be referred to as network element discovery request 2) to the NRF network element. Network element discovery request 2 includes a temporary identifier of the first target network element. The NRF network element can send the profile of the first target network element to the second routing network element based on the temporary identifier of the first target network element in network element discovery request 2. The first routing network element then sends a second uplink NAS message to the first target network element based on the profile of the first target network element (e.g., the FQDN of the first target network element).

[0387] It should be added that the terminal can obtain the temporary identifier of the first target network element not only from the first routing network element, but also from other routing network elements (denoted as the third routing network element). For specific implementation details, please refer to the above. Figure 7 The descriptions in the relevant embodiments can be understood by replacing "first target network element" with "second target network element" and "first routing network element" with "third routing network element".

[0388] The temporary identifier of the second target network element may include the identifier of the third routing network element. For example, the temporary identifier of the second target network element may also include information used on the third routing network element to uniquely identify the second target network element.

[0389] The terminal can also send a third uplink NAS message, which carries a temporary identifier of the second target network element. The second target network element is the network element used to process the third uplink NAS message. For the relationship between the third uplink NAS message and the second target network element, please refer to the description of the relationship between the second uplink NAS message and the first target network element in the above embodiments.

[0390] In one possible implementation, the terminal sends a third uplink NAS message. This third uplink NAS message is received by the first routing network element; that is, the first routing network element receives the third uplink NAS message from the terminal and obtains the temporary identifier of the second target network element from the third uplink NAS message. The first routing network element can determine that it does not have a mapping relationship between the temporary identifier and the internal identifier of the second target network element stored locally. Therefore, the first routing network element can send a second request to the third routing network element based on the identifier of the third routing network element in the temporary identifier of the second target network element. The second request is used to request the internal identifier of the second target network element, and the second request includes the temporary identifier of the second target network element. Correspondingly, the third routing network element receives the second request from the first routing network element, determines the internal identifier of the second target network element based on the temporary identifier of the second target network element in the second request and the mapping relationship between the temporary identifier and the internal identifier of the second target network element stored locally, and sends the internal identifier of the second target network element to the first routing network element. The first routing network element then sends a third uplink NAS message to the second target network element based on the internal identifier of the second target network element.

[0391] In this process, the first routing network element sends a third uplink NAS message to the second target network element based on the internal identifier of the second target network element. This is similar to the implementation of the second routing network element sending a second uplink NAS message to the first target network element based on the internal identifier of the first target network element in method b above, and will not be described in detail here.

[0392] Alternatively, after determining that it does not locally store the mapping relationship between the temporary identifier and the internal identifier of the second target network element, the first routing network element sends a second request to the third routing network element. This second request requests the mapping relationship between the temporary identifier and the internal identifier of the second target network element, and includes the temporary identifier of the second target network element. Correspondingly, the third routing network element receives the second request from the first routing network element and, based on the temporary identifier of the second target network element in the second request, sends the mapping relationship back to the first routing network element. The first routing network element then sends a third uplink NAS message to the second target network element based on this mapping relationship.

[0393] In this process, the first routing network element sends a third uplink NAS message to the second target network element according to the mapping relationship. This is similar to the implementation of the second routing network element sending a second uplink NAS message to the first target network element according to the mapping relationship in method c above, and will not be described in detail here.

[0394] Alternatively, after determining that the first routing network element does not have a mapping relationship between the temporary identifier and the internal identifier of the second target network element stored locally, it sends a third uplink NAS message to the third routing network element based on the identifier of the third routing network element in the temporary identifier of the second target network element. Correspondingly, the third routing network element receives the third uplink NAS message from the first routing network element, determines the internal identifier of the second target network element based on the mapping relationship between the temporary identifier and the internal identifier of the second target network element in the third uplink NAS message, and sends a third uplink NAS message to the second target network element.

[0395] Alternatively, the first routing network element sends a network element discovery request to the NRF network element (distinct from the network element discovery request in step 702; this network element discovery request can be referred to as network element discovery request 3). Network element discovery request 3 includes a temporary identifier of the second target network element. The NRF network element can send the internal identifier of the second target network element to the first routing network element based on the temporary identifier of the second target network element in network element discovery request 3. The first routing network element then sends a third uplink NAS message to the second target network element based on the internal identifier of the second target network element.

[0396] It is understandable that the first routing network element can perform a network element discovery process based on the temporary identifier of the second target network element to discover the internal identifier of the second target network element. Here, the NRF network element includes a mapping relationship between the temporary identifier and the internal identifier of the second target network element. The temporary identifier of the second target network element can be generated by the NRF network element, or generated by the second target network element and sent to the NRF network element.

[0397] For example, the NRF network element sends the profile of the second target network element to the first routing network element. The profile of the second target network element includes the internal identifier of the second target network element. For example, the second target network element then sends a third uplink NAS message to the second target network element based on its profile (e.g., the FQDN of the second target network element).

[0398] In this application, "the first routing network element determines that it does not have a mapping relationship between the temporary identifier of the second target network element and the internal identifier of the second target network element stored locally" can be replaced with "the first routing network element cannot determine the internal identifier of the second target network element", or "the first routing network element cannot determine the internal identifier of the second target network element based on the temporary identifier of the second target network element", or "the first routing network element cannot determine the second target network element", or "the first routing network element cannot determine the second target network element based on the temporary identifier of the second target network element", etc.

[0399] Similarly, "the second routing network element determines that it does not have a mapping relationship between the temporary identifier of the first target network element and the internal identifier of the first target network element stored locally" can be replaced with "the second routing network element cannot determine the internal identifier of the first target network element", or "the second routing network element cannot determine the internal identifier of the first target network element based on the temporary identifier of the first target network element", or "the second routing network element cannot determine the first target network element", or "the second routing network element cannot determine the first target network element based on the temporary identifier of the first target network element", etc.

[0400] In another possible implementation, the third uplink NAS message includes a temporary identifier of the second target network element, which may further include the identifier of the NRF network element. Correspondingly, after receiving the third uplink NAS message, the first routing network element may send a second request to the NRF network element to request the internal identifier of the second target network element; or, to request the mapping relationship between the temporary identifier of the second target network element and the internal identifier of the second target network element. The specific implementation of the first routing network element sending a second request to the third routing network element is described above and will not be elaborated further.

[0401] It should also be noted that in steps 704 and 705 above, the first target network element can also send a first downlink NAS message to other routing network elements. These other routing network elements then route the first downlink NAS message to the terminal. That is, this application does not limit the network element routing the first uplink NAS message and the network element routing the first downlink NAS message to the same routing network element. For example, after receiving the first downlink NAS message, the other routing network element can obtain the terminal identifier from the first routing network element and send the first downlink NAS message based on the terminal identifier. In other words, this application does not limit the network element routing the uplink NAS message and the network element routing the downlink NAS message to the same routing network element.

[0402] like Figure 8 This is a flowchart illustrating a second communication method provided as an example in this application. The first target network element is AMF network element 3, and the temporary identifier of AMF network element 3 is generated by the first routing network element. The first information is located outside the first uplink NAS message.

[0403] Understandable, Figure 8 The relevant embodiments are Figure 7 One specific implementation of the related embodiments, Figure 8 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments.

[0404] Step 801: The terminal sends a first uplink NAS message and first information. This first uplink NAS message and first information are received by the first routing network element; that is, the first routing network element receives the first uplink NAS message and first information from the terminal.

[0405] Before sending the first uplink NAS message, the terminal determines fourth information based on the first uplink NAS message to be sent. The fourth information includes one or more of the following: EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. For example, the fourth information could be a combination of EPD and slice identifier, such as "EPD2 and S-NSSAI 3". Further, the terminal's local storage mapping relationship is shown in Table 1 above. Based on the fourth information and the local storage mapping relationship, the terminal determines that there is no temporary identifier for the first target network element, and therefore sets the receiver information field in the first uplink NAS message to empty. The terminal can also determine that the first information is "EPD2 and S-NSSAI 3".

[0406] For example, the recipient information field is located in the header of the first uplink NAS message.

[0407] For example, the first uplink NAS message does not include the temporary identifier of the first target network element.

[0408] For example, the message type of the first uplink NAS message is a registration request. The first uplink NAS message can also be referred to as a registration request message.

[0409] For example, the terminal establishes an air interface connection with the RAN, and the RAN stores the terminal's temporary identifier (such as RNTI) on the air interface. When initiating registration, the terminal can send a registration request message to the RAN, which may include the terminal's SUCI, access network parameters, etc. The RAN sends an initial terminal message to the first routing network element, which may include the UE's identifier on the RAN (e.g., the RAN UE NGAP ID assigned to the terminal by the RAN) and the terminal's registration request message (which includes the terminal's SUCI and has an empty receiver information field).

[0410] For details not described in step 801, please refer to the description in step 701 above.

[0411] Step 802: If the first routing network element determines that the receiver information field in the first uplink NAS message is empty, it sends a network element discovery request to the NRF network element. Correspondingly, the NRF network element receives the network element discovery request from the first routing network element. The network element discovery request includes second information, which is determined based on the first information. For example, the second information is the same as the first information, i.e., the second information is "EPD2 and S-NSSAI 3".

[0412] Step 803: The NRF network element executes the network element discovery process based on the second information included in the network element discovery request, determines that the first target network element is AMF network element 3, and sends a network element discovery response to the first routing network element. The network element discovery response includes the internal identifier of AMF network element 3.

[0413] For details not described in steps 802 and 803, please refer to the description in step 702 above.

[0414] Step 804: The first routing network element sends the first uplink NAS message to AMF network element 3 according to the internal identifier of AMF network element 3.

[0415] For example, the first routing network element sends a first SBI message to AMF network element 3 based on the internal identifier of AMF network element 3. The first SBI message includes a first uplink NAS message. AMF network element 3 receives the first SBI message from the first routing network element.

[0416] For details not described in step 804, please refer to the description in step 703 above.

[0417] Step 805: AMF network element 3 sends the first downlink NAS message to the first routing network element.

[0418] For example, AMF element 3 processes the first uplink NAS message to obtain the response message (i.e., the first downlink NAS message) corresponding to the first uplink NAS message. AMF element 3 then sends the first downlink NAS message to the first routing element.

[0419] For example, AMF network element 3 obtains the first uplink NAS message from the first SBI message, processes the first uplink NAS message, and then sends a second SBI message to the first routing network element. The second SBI message includes the first downlink NAS message.

[0420] The first downlink NAS message can also be called the registration acceptance message.

[0421] For example, the temporary identifier of AMF element 3 can also be carried in the first downlink NAS message.

[0422] For details not described in step 805, please refer to the description in step 704 above.

[0423] Step 806: The first routing network element generates a temporary identifier for AMF network element 3. It is understood that step 806 is after step 802 and before step 807, but the order of step 806 and step 803 (or step 804, or step 805) is not limited.

[0424] For details not described in step 806, please refer to the description in step 702 above.

[0425] Step 807: The first routing network element sends a first downlink NAS message and a temporary identifier of AMF network element 3 to the terminal. Correspondingly, the terminal receives the first downlink NAS message and the temporary identifier of AMF network element 3.

[0426] For example, AMF element 3 sends an Initial Context Establishment Request (IPFR) message to the first routing element. The first routing element then forwards the IPR and the temporary identifier of AMF element 3 to the RAN. The IPR may include the RAN UE NGAP ID, the AMF UE NGAP ID (i.e., the NGAP identifier assigned to the terminal by the AMF element), and a registration acceptance message to the terminal (as an example of a first downlink NAS message). The RAN then sends the registration acceptance message and the temporary identifier of AMF element 3 to the terminal.

[0427] For details not described in step 807, please refer to the description in step 705 above.

[0428] Step 808: The terminal saves the mapping relationship between the first information and the temporary identifier of AMF network element 3.

[0429] For example, the terminal establishes a mapping relationship between "EPD2 and S-NSSAI 3" and the temporary identifier of AMF network element 3.

[0430] For details not described in step 808, please refer to the description in step 705 above.

[0431] Optional, also includes:

[0432] Step 809: The terminal sends a second uplink NAS message. This second uplink NAS message is received by the first routing network element; that is, the first routing network element receives the second uplink NAS message from the terminal.

[0433] Specifically, before sending the second uplink NAS message, the terminal determines the fourth information corresponding to the second uplink NAS message. For example, the fourth information is "EPD2 and S-NSSAI 3". Based on the mapping relationship between the fourth information and local storage, the terminal determines that "EPD2 and S-NSSAI 3" corresponds to the temporary identifier of AMF network element 3, and sets the receiver information field in the second uplink NAS message to the temporary identifier of AMF network element 3.

[0434] For example, the recipient information field (i.e., the temporary identifier of AMF element 3) is located in the header of the second uplink NAS message.

[0435] For example, the second uplink NAS message is encrypted.

[0436] Step 810: The first routing network element obtains the temporary identifier of AMF network element 3 from the second uplink NAS message, and determines the internal identifier of AMF network element 3 according to the mapping relationship between the temporary identifier and the internal identifier of AMF network element 3 stored locally.

[0437] Step 811: The first routing network element sends a second uplink NAS message to AMF network element 3 based on the internal identifier of AMF network element 3.

[0438] For example, the first routing element sends a third SBI message to AMF element 3 based on the internal identifier of AMF element 3. The third SBI message includes a second uplink NAS message. AMF element 3 receives the third SBI message from the first routing element.

[0439] Step 812: AMF network element 3 sends a second downlink NAS message to the first routing network element.

[0440] For example, AMF element 3 processes the second uplink NAS message to obtain the response message (i.e., the second downlink NAS message) corresponding to the second uplink NAS message. AMF element 3 then sends the second downlink NAS message to the first routing element.

[0441] For example, AMF network element 3 obtains the second uplink NAS message from the third SBI message, processes the second uplink NAS message, and then sends a fourth SBI message to the first routing network element. The fourth SBI message includes the second downlink NAS message.

[0442] The second downlink NAS message can also be called a service acceptance message.

[0443] Step 813: The first routing network element sends a second downlink NAS message to the terminal. The terminal receives the second downlink NAS message.

[0444] For details not described in steps 809 to 813, please refer to the description following step 705 above.

[0445] Figure 8Not all of the steps shown are mandatory, and the content transmitted between the two network elements / devices is also optional. These steps can be removed or additional steps or transmitted content can be added as needed. For example, in step 802, the first routing network element may not send a network element discovery request to the NRF network element, but instead forward all or part of the first information and the first uplink NAS message; for example, step 806 may not exist; for example, in step 807, the first routing network element may not send the temporary identifier of AMF network element 3 to the terminal; for example, steps 808 to 813 may not exist. Other variations can be found in [reference needed]. Figure 7 As described in the relevant embodiments.

[0446] like Figure 9 This is a flowchart illustrating a third communication method provided as an example in this application. The first target network element is AMF network element 3, and the temporary identifier of AMF network element 3 is generated by the NRF network element. The first information is located outside the first uplink NAS message.

[0447] Understandable, Figure 9 The relevant embodiments are Figure 7 One specific implementation of the related embodiments, Figure 9 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments. Figure 9 Related Implementation Examples and Figure 8 The difference between the related embodiments lies in the subject that generates the temporary identifier of the first target network element (e.g., AMF network element 3). Figure 9 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 8 The description in the relevant embodiments.

[0448] Step 901: The terminal sends a first uplink NAS message and first information. This first uplink NAS message and first information are received by the first routing network element; that is, the first routing network element receives the first uplink NAS message and first information from the terminal.

[0449] The message type of the first uplink NAS message is, for example, a registration request. See step 801 for a detailed implementation description.

[0450] Step 902: When the first routing network element determines that the receiver information field in the first uplink NAS message is empty, it sends a network element discovery request to the NRF network element. Correspondingly, the NRF network element receives the network element discovery request from the first routing network element.

[0451] The network element discovery request includes a second piece of information, which is determined based on the first piece of information. For example, the second piece of information is the same as the first piece of information, that is, the second piece of information is "EPD2 and S-NSSAI 3".

[0452] The network element discovery request also includes third information, which may include one or more of the following: NAS type (i.e., mobility management type), NAS message type (i.e., registration request), indication of generating a temporary identifier for the first target network element, indication of the existence of downlink NAS messages in the network, indication of the existence of other uplink NAS messages in the network, consumer field, and service name field; the value of the consumer field is the identifier of the first routing network element; the value of the service name field is the service that forwards the NAS message.

[0453] The definitions of each parameter in the network element discovery request can be found in the description in step 702 above.

[0454] Step 903: The NRF network element executes the network element discovery process based on the second information included in the network element discovery request, and determines that the first target network element is AMF network element 3. The NRF network element also generates a temporary identifier for AMF network element 3 based on the third information included in the network element discovery request. The NRF network element sends a network element discovery response to the first routing network element, which includes the internal identifier and temporary identifier of AMF network element 3.

[0455] Step 904: The first routing network element sends the first uplink NAS message to AMF network element 3 according to the internal identifier of AMF network element 3.

[0456] For example, the first routing network element obtains the internal identifier and temporary identifier of AMF network element 3 from the network element discovery response. The first routing network element then sends a first uplink NAS message to AMF network element 3 based on the internal identifier of AMF network element 3. Additionally, in step 906 below, the temporary identifier of AMF network element 3 is sent to the terminal. Other details not described in this step can be found in the description of step 804.

[0457] Step 905: AMF network element 3 sends the first downlink NAS message to the first routing network element.

[0458] For example, AMF element 3 processes the first uplink NAS message to obtain the response message (i.e., the first downlink NAS message) corresponding to the first uplink NAS message. AMF element 3 then sends the first downlink NAS message to the first routing element.

[0459] For a detailed implementation, please refer to the description in step 805.

[0460] Step 906: The first routing network element sends a first downlink NAS message and a temporary identifier of AMF network element 3 to the terminal. Correspondingly, the terminal receives the first downlink NAS message and the temporary identifier of AMF network element 3.

[0461] The temporary identifier of AMF element 3 can be located inside or outside the first downlink NAS message.

[0462] Step 907: The terminal saves the mapping relationship between the first information and the temporary identifier of AMF network element 3.

[0463] Optional, also includes:

[0464] Step 908: The terminal sends a second uplink NAS message. This second uplink NAS message is received by the first routing network element; that is, the first routing network element receives the second uplink NAS message from the terminal. The second uplink NAS message is, for example, a service request message.

[0465] Step 909: The first routing network element obtains the temporary identifier of AMF network element 3 from the second uplink NAS message, and determines the internal identifier of AMF network element 3 according to the mapping relationship between the temporary identifier and the internal identifier of AMF network element 3 stored locally.

[0466] Step 910: The first routing network element sends a second uplink NAS message to AMF network element 3 based on the internal identifier of AMF network element 3.

[0467] Step 911: AMF network element 3 sends a second downlink NAS message to the first routing network element.

[0468] For example, AMF element 3 processes the second uplink NAS message to obtain the response message (i.e., the second downlink NAS message) corresponding to the second uplink NAS message. AMF element 3 then sends the second downlink NAS message to the first routing element.

[0469] The second downlink NAS message is, for example, a service acceptance message.

[0470] Step 912: The first routing network element sends a second downlink NAS message to the terminal. The terminal receives the first downlink NAS message.

[0471] Steps 906 to 912 correspond to steps 807 to 813 above. For details not described in detail, please refer to the relevant documents. Figure 8 The descriptions in the relevant embodiments will not be repeated here.

[0472] Figure 9Not all of the steps shown are mandatory, and the content transmitted between the two network elements / devices is also optional. These steps can be removed or additional steps or transmitted content can be added as needed. For example, in step 902, the first routing network element may not send a network element discovery request to the NRF network element, but instead forward all or part of the first information and the first uplink NAS message; for example, in step 903, the network element discovery response does not include the temporary identifier of AMF network element 3; for example, in step 906, the first routing network element may not send the temporary identifier of AMF network element 3 to the terminal; for example, steps 907 to 912 are not present.

[0473] Other variations can be found in [the following text is also available]. Figure 7 As described in the relevant embodiments.

[0474] like Figure 10 This is a flowchart illustrating the fourth communication method provided as an example in this application. The first target network element is AMF network element 3, and the temporary identifier of AMF network element 3 is generated by the first routing network element. The first information is located within the first uplink NAS message.

[0475] Understandable, Figure 10 The relevant embodiments are Figure 7 One specific implementation of the related embodiments, Figure 10 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments. Figure 10 Related Implementation Examples and Figure 8 The difference between the related embodiments lies in whether the first information is located outside or inside the first uplink NAS message. Figure 10 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 8 The description in the relevant embodiments.

[0476] Step 1001: The terminal sends a first uplink NAS message and first information. This first uplink NAS message and first information are received by the first routing network element; that is, the first routing network element receives the first uplink NAS message and first information from the terminal.

[0477] The first information includes one or more of the following: EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. For example, the first information may be a combination of EPD and slice identifier, such as "EPD2 and S-NSSAI 3".

[0478] Before sending the first uplink NAS message, the terminal determines the first information corresponding to the first uplink NAS message, namely, "EPD2 and S-NSSAI 3" mentioned above. Further, the mapping relationship of the terminal's local storage is shown in Table 1 above. Based on the fourth information and the mapping relationship of the local storage, the terminal determines that there is no temporary identifier of the first target network element, and therefore sets the receiver information field in the first uplink NAS message to empty.

[0479] For example, the first uplink NAS message does not include a temporary identifier for the first target network element. For example, the receiver information field is located in the header of the first uplink NAS message, and the value of the receiver information field is empty.

[0480] For example, the message type of the first uplink NAS message is a registration request. The first uplink NAS message can also be referred to as a registration request message.

[0481] For example, the first information (e.g., “EPD2 and S-NSSAI 3”) is located in the header of the first uplink NAS message.

[0482] For example, part of the first information (e.g., “EPD2”) is located in the header of the first uplink NAS message, and another part (e.g., “S-NSSAI 3”) is located in the payload of the first uplink NAS message, which is in plaintext.

[0483] Alternatively, it can be understood that one or more of the following are fields of existing NAS messages: EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. This application may not improve the fields / information elements in the NAS message, and the first routing network element may obtain the first information from the NAS message based on the plaintext NAS message, and then request the internal identifier of the first target network element (or the internal identifier and temporary identifier of the first target network element) according to the first information.

[0484] For other details not described in this step, please refer to the description in step 801.

[0485] Step 1002: When the first routing network element determines that the receiver information field in the first uplink NAS message is empty, it sends a network element discovery request to the NRF network element. Correspondingly, the NRF network element receives the network element discovery request from the first routing network element.

[0486] For example, the first routing network element first determines whether the receiver information field in the header of the first uplink NAS message is empty. If it is determined to be empty, it obtains the EPD (e.g., "EPD2") from the header and parses the payload of the first uplink NAS message to obtain the slice identifier (e.g., "S-NSSAI 3") in the payload. In addition, when the first information also includes one or more of the message type and network element type, the first routing network element can also obtain one or more of the message type and network element type from the header; when the first information also includes one or more of the subnet identifier and PDU session identifier, the first routing network element can also obtain one or more of the subnet identifier and PDU session identifier from the payload.

[0487] Steps 1003 to 1013 correspond to steps 803 to 813 above, respectively. For details not described in detail, please refer to the relevant documents. Figure 8 The descriptions in the relevant embodiments will not be repeated here.

[0488] Figure 10 Not all of the steps shown are mandatory, and the content transmitted between the two network elements / devices is also optional. These steps can be removed or additional steps or transmitted content can be added as needed. For example, in step 1002, the first routing network element may not send a network element discovery request to the NRF network element, but instead forward all or part of the first uplink NAS message, and this first uplink NAS message may include the first information. For example, in step 1006, the first routing network element may not generate a temporary identifier for AMF network element 3. For example, in step 1007, the first routing network element may not send the temporary identifier of AMF network element 3 to the terminal. For example, steps 1008 to 1013 may not exist. Other variations can be found in [reference needed]. Figure 7 As described in the relevant embodiments.

[0489] It is understandable that the first information is located within the first uplink NAS message, and the temporary identifier of AMF network element 3 is generated by the NRF network element, which can be based on... Figure 9 Related embodiments and Figure 10 The relevant embodiments were obtained. Further details will not be elaborated upon in this application.

[0490] like Figure 11 This is a flowchart illustrating the fifth communication method provided as an example in this application.

[0491] The first routing network element stores the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3. The terminal sends a second uplink NAS message, which is received by the second routing network element. The temporary identifier of AMF network element 3 is carried in the second uplink NAS message. AMF network element 3 is the network element that processes the second uplink NAS message.

[0492] Understandable, Figure 11 The relevant embodiments are Figure 7 One specific implementation of the related embodiments, Figure 11 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments.

[0493] Step 1101: The terminal sends a second uplink NAS message. This second uplink NAS message is received by the second routing network element; that is, the second routing network element receives the second uplink NAS message from the terminal.

[0494] Specifically, before sending the second uplink NAS message, the terminal determines the fourth information corresponding to the second uplink NAS message. For example, the fourth information is "EPD2 and S-NSSAI 3". Based on the mapping relationship between the fourth information and local storage, the terminal determines that "EPD2 and S-NSSAI 3" corresponds to the temporary identifier of AMF network element 3, and sets the receiver information field in the second uplink NAS message to the temporary identifier of AMF network element 3.

[0495] For example, the recipient information field (i.e., the temporary identifier of AMF element 3) is located in the header of the second uplink NAS message.

[0496] For example, the second uplink NAS message is encrypted.

[0497] Step 1102: The second routing network element obtains the temporary identifier of AMF network element 3 from the second uplink NAS message and sends a first request to the first routing network element. The first request includes the temporary identifier of AMF network element 3 and is used to request the internal identifier of AMF network element 3.

[0498] For example, the second routing network element does not store the mapping relationship between the temporary identifier of AMF network element 3 and the internal identifier of AMF network element 3.

[0499] For example, the temporary identifier of AMF network element 3 includes the identifier of the first routing network element and information used on the first routing network element to uniquely identify AMF network element 3. The second routing network element can first determine that it does not store a mapping relationship between the internal identifier and the temporary identifier of AMF network element 3 locally, then obtain the identifier of the first routing network element from the temporary identifier of AMF network element 3, and send a first request to the first routing network element according to the identifier of the first routing network element. The first request includes the temporary identifier of AMF network element 3.

[0500] Step 1103: The first routing network element sends the internal identifier of AMF network element 3 to the second routing network element.

[0501] For example, the first routing network element obtains the temporary identifier of AMF network element 3 from the first request, determines the internal identifier of AMF network element 3 based on the temporary identifier of AMF network element 3, the mapping relationship between the internal identifier of AMF network element 3 stored locally and the temporary identifier, and sends the internal identifier of AMF network element 3 to the second routing network element.

[0502] For another example, the first routing network element obtains the temporary identifier of AMF network element 3 from the first request, and based on the temporary identifier of AMF network element 3, obtains the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3 from the local storage, and sends the mapping relationship to the second routing network element.

[0503] Step 1104: The second routing network element sends a second uplink NAS message to AMF network element 3 based on the internal identifier of AMF network element 3.

[0504] For example, when the first routing network element sends the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3 to the second routing network element, the second routing network element can also determine the internal identifier of AMF network element 3 based on the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3, and then send a second uplink NAS message to AMF network element 3.

[0505] Step 1105: AMF network element 3 sends a second downlink NAS message to the second routing network element.

[0506] For example, AMF element 3 processes the second uplink NAS message to obtain the response message (i.e., the second downlink NAS message) corresponding to the second uplink NAS message. AMF element 3 then sends the second downlink NAS message to the second routing element.

[0507] Step 1106: The second routing network element sends a second downlink NAS message to the terminal. The terminal receives the second downlink NAS message from the second routing network element.

[0508] It is understandable that when the temporary identifier of AMF network element 3 includes the identifier of the NRF network element and the information used to uniquely identify AMF network element 3 on the NRF network element, the second routing network element can also request the internal identifier of AMF network element 3 from the NRF network element. For specific implementation details, please refer to the above. Figure 11 In the descriptions of the relevant embodiments, "first routing network element" can be replaced with "NRF network element" for better understanding.

[0509] Figure 11 Not all of the steps shown are mandatory, and the content transmitted between the two network elements / devices is also optional. These steps can be removed or additional steps or transmitted content can be added as needed. For example, steps 1105 and 1106 are not required; instead, AMF network element 3 sends a second downlink NAS message to the first routing network element, and the first routing network element sends a second downlink NAS message to the terminal.

[0510] Other variations can be found in [the following text is also available]. Figure 7 As described in the relevant embodiments.

[0511] like Figure 12 This is a flowchart illustrating the sixth communication method provided as an example in this application.

[0512] The first routing network element stores the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3. The terminal sends a second uplink NAS message, which is received by the second routing network element. The temporary identifier of AMF network element 3 is carried in the second uplink NAS message. AMF network element 3 is the network element that processes the second uplink NAS message.

[0513] Understandable, Figure 12 The relevant embodiments are Figure 7 One specific implementation of the related embodiments, Figure 12 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments.

[0514] Step 1201: The terminal sends a second uplink NAS message. This second uplink NAS message is received by the second routing network element; that is, the second routing network element receives the second uplink NAS message from the terminal. For a detailed implementation, please refer to the description in step 1101.

[0515] Step 1202: The second routing network element obtains the temporary identifier of AMF network element 3 from the second uplink NAS message and sends the second uplink NAS message to the first routing network element.

[0516] For example, the temporary identifier of AMF network element 3 includes the identifier of the first routing network element and information used to uniquely identify AMF network element 3 on the first routing network element. The second routing network element obtains the identifier of the first routing network element from the temporary identifier of AMF network element 3, and sends a second uplink NAS message to the first routing network element based on the identifier of the first routing network element. For example, the second routing network element may determine before sending the second uplink NAS message to the first routing network element that it does not locally store the mapping relationship between the internal identifier and the temporary identifier of AMF network element 3.

[0517] Step 1203: The first routing network element determines the internal identifier of AMF network element 3 based on the temporary identifier of AMF network element 3 carried in the second uplink NAS message and the mapping relationship between the internal identifier and temporary identifier of AMF network element 3 stored locally.

[0518] Step 1204: The first routing network element sends a second uplink NAS message to AMF network element 3 based on the internal identifier of AMF network element 3.

[0519] Step 1205: AMF network element 3 sends a second downlink NAS message to the first routing network element.

[0520] For example, AMF element 3 processes the second uplink NAS message to obtain the response message (i.e., the second downlink NAS message) corresponding to the second uplink NAS message. AMF element 3 then sends the second downlink NAS message to the first routing element.

[0521] Step 1206: The first routing network element sends a second downlink NAS message to the terminal. The terminal receives the second downlink NAS message.

[0522] Understandably, the second routing element can be a lightweight routing element. The second routing element does not store the mapping relationship between the element's temporary identifier and internal identifier. When the second routing element receives an uplink NAS message, it can forward the uplink NAS message to other routing elements, or request the element's internal identifier from other routing elements or NRF elements.

[0523] Figure 12 Not all of the steps shown are mandatory, and the content transmitted between the two network elements / devices is also optional. These steps can be removed or additional steps or transmitted content can be added as needed. For example, steps 1205 and 1206 are not required; instead, AMF network element 3 sends a second downlink NAS message to the second routing network element, and the second routing network element sends a second downlink NAS message to the terminal.

[0524] Other variations can be found in [the following text is also available]. Figure 7 As described in the relevant embodiments.

[0525] It should be added that, in the above Figures 7 to 12 In related embodiments, the network element discovery response may further include a temporary identifier of the first target network element. For example, the network element discovery response may include the profile of the first target network element, and the profile of the first target network element may include the temporary identifier of the first target network element. Alternatively, the profile of the first target network element may not include the internal identifier of the first target network element.

[0526] Figure 13 This is a flowchart illustrating the seventh communication method provided as an example in this application.

[0527] Understandable, Figure 13 Related Implementation Examples and Figure 7 The difference in the relevant embodiments lies in whether the first routing network element routes the first uplink NAS message based on the internal identifier of the first destination network element, or based on the temporary identifier of the first destination network element. Figure 13 For any terms or technical solutions not described in detail in the relevant embodiments, please refer to [link / reference needed]. Figure 7 The description in the relevant embodiments.

[0528] Step 1301: The terminal sends a first uplink NAS message and first information. This first uplink NAS message and first information are received by the first routing network element; that is, the first routing network element receives the first uplink NAS message and first information from the terminal.

[0529] For details not described in full, please refer to the description in step 701 above.

[0530] Optionally, prior to step 1301, the following steps are also included:

[0531] Step 1300: The first target network element sends its temporary identifier to the NRF network element.

[0532] For example, during the registration process of the first target network element with the NRF network element, a temporary identifier of the first target network element is sent to the NRF network element. For example, the first target network element sends a network element registration request (NF resister request) to the NRF network element, and the network element registration request includes the temporary identifier of the first target network element. For instance, the first target network element generates its own temporary identifier.

[0533] For example, the temporary identifier of the first target network element includes the identifier of the first target network element and information used to uniquely identify the first target network element. For example, the temporary identifier of the first target network element consists of the identifier of the first target network element and information used to uniquely identify the first target network element. The identifier of the first target network element is distinguished from the temporary identifier of the first target network element (e.g., composed of the identifier of the first target network element and information used to uniquely identify the first target network element) or the internal identifier of the first target network element (e.g., the instance ID of the first target network element). For details, please refer to the description in step B above.

[0534] In addition, the configuration file of the first target network element also includes one or more of the following: the internal identifier of the first target network element, the network element type, the subnet identifier where the network element is located, the S-NSSAI list supported by the network element, the IP address of the network element, the port number of the network element, and the geographical location information of the network element.

[0535] Optionally, the NRF network element stores the configuration file of the first target network element.

[0536] Of course, the temporary identifier of the first target network element can also be generated by the first routing network element or the NRF network element.

[0537] For example, the temporary identifier of the first target network element may also include one or more of the following: the identifier of the first routing network element, information used to uniquely identify the first target network element on the first routing network element, the identifier of the NRF network element, and information used to uniquely identify the first target network element on the NRF network element. For further explanation of each parameter, please refer to the description in step B above.

[0538] Step 1302: The first routing network element obtains the temporary identifier of the first target network element. Step 1302 is an optional step.

[0539] In one possible implementation, the first routing network element obtains the temporary identifier of the first target network element through the network element discovery process, as detailed in steps (A) to (C) below:

[0540] In step (A), the first routing network element sends a network element discovery request to the NRF network element, and correspondingly, the NRF network element receives the network element discovery request from the first routing network element. The network element discovery request includes second information, which is used to determine the first target network element.

[0541] For details not described in full, please refer to the description in step A of step 702 above.

[0542] In step (B), the NRF network element determines the first target network element based on the second information in the network element discovery request.

[0543] For details not described in full, please refer to step B of step 702 above.

[0544] In step (C), the NRF network element sends a network element discovery response to the first routing network element, and correspondingly, the first routing network element receives the network element discovery response from the NRF network element. The network element discovery response includes a temporary identifier of the first target network element.

[0545] For example, the network element discovery response includes the profile of the first target network element, and the profile of the first target network element includes a temporary identifier of the first target network element. For example, the network element discovery response does not include the internal identifier of the first target network element; however, for another example, the network element discovery response may also include the internal identifier of the first target network element, for example, the profile of the first target network element may also include the internal identifier of the first target network element.

[0546] For details not described in full, please refer to the description in step C of step 702 above.

[0547] In another possible implementation, the first routing network element forwards a first uplink NAS message to the NRF network element. The NRF network element parses the first uplink NAS message, obtains first information from it, and then determines the first target network element based on the first information. The NRF network element sends a temporary identifier of the first target network element to the first routing network element. Optionally, after determining that the received SBI message carries the first uplink NAS message, the NRF network element may decide to send a temporary identifier of the first target network element to the first routing network element. For example, the NRF network element may also send the profile of the first target network element to the first routing network element. For instance, after receiving the temporary identifier of the first target network element from the NRF network element, the first routing network element requests the profile of the first target network element from the NRF network element based on the temporary identifier.

[0548] Step 1303: The first routing network element sends a first uplink NAS message to the first target network element based on the temporary identifier of the first target network element. Correspondingly, the first target network element receives the first uplink NAS message from the first routing network element.

[0549] For example, the first routing network element determines the profile of the first target network element based on the temporary identifier of the first target network element, and sends the first uplink NAS message to the first target network element based on the profile of the first target network element (e.g., the FQDN of the first target network element).

[0550] For details not described in full, please refer to the description in step 703 above.

[0551] Step 1304: The first target network element sends a first downlink NAS message to the first routing network element. Correspondingly, the first routing network element receives the first downlink NAS message from the first target network element. For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0552] For example, the first downlink NAS message includes a sender information field, which contains information about the sender of the first downlink NAS message. For instance, the value of the sender information field is a temporary identifier of the first target network element.

[0553] The following are two examples of the first target network element sending the first downlink NAS message to the first routing network element:

[0554] Example (A): Considering the integrity protection and encryption of NAS messages, after the first target network element sets the value of the sender information field to the temporary identifier of the first target network element, it can perform integrity protection and encryption on the first downlink NAS message (containing the sender information field) to obtain the first downlink NAS message after integrity protection and encryption, and send the first downlink NAS message after integrity protection and encryption to the first routing network element.

[0555] Example (B): The first target network element sends a first downlink NAS message and a temporary identifier of the first target network element to the first routing network element. That is, the temporary identifier of the first target network element is located outside the first downlink NAS message. For example, the sender information field in the first downlink NAS message is empty. Another example is that both the first downlink NAS message and the temporary identifier of the first target network element are included in the second SBI message.

[0556] For details not described in full, please refer to the description in step 704 above.

[0557] Step 1305: The first routing network element sends a first downlink NAS message and a temporary identifier of the first target network element to the terminal. Correspondingly, the terminal receives the first downlink NAS message and the temporary identifier of the first target network element.

[0558] For example, if the first routing network element determines that there will be further uplink NAS messages between the terminal and the first target network element, it may send a temporary identifier of the first target network element to the terminal. In other words, if there are no further uplink NAS messages between the terminal and the first target network element, the first routing network element does not need to send the temporary identifier of the first target network element to the terminal.

[0559] Furthermore, in the example (B) above, the first routing network element can also perform integrity protection and encryption on the first downlink NAS message and the temporary identifier of the first target network element.

[0560] For details not described in full, please refer to the description in step 705 above.

[0561] For the terminal, it can also store the mapping relationship between the first information and the temporary identifier of the first target network element. Alternatively, the terminal can also store the mapping relationship between the fifth information and the temporary identifier of the first target network element, wherein the fifth information and the first information are associated. For ease of description, the following explanation uses the terminal storing the mapping relationship between the first information and the temporary identifier of the first target network element as an example.

[0562] Subsequently, before sending the second uplink NAS message, the terminal can determine the temporary identifier of the first target network element based on the mapping relationship between the saved first information and the temporary identifier of the first target network element, and carry the temporary identifier of the first target network element in the second uplink NAS message.

[0563] It can be understood that the second uplink NAS message is another uplink NAS message sent by the terminal to the first target network element, and the second uplink NAS message is located after the first uplink NAS message. For example, the fourth information corresponding to the second uplink NAS message is the same as the fourth information corresponding to the first uplink NAS message. See "Relationship between the first uplink NAS message and the second uplink NAS message" in step 705 above.

[0564] For example, after receiving the second uplink NAS message, the first routing network element obtains the profile of the first target network element based on the temporary identifier of the first target network element in the second uplink NAS message (for example, the first routing network element has the profile of the first target network element stored locally), and then sends the second uplink NAS message based on the profile of the first target network element (for example, the FQDN of the first target network element).

[0565] Of course, the second uplink NAS message sent by the terminal can be received not only by the first routing network element but also by the second routing network element. In this case, the second routing network element does not store the temporary identifier of the first target network element and cannot obtain its profile. Therefore, the second routing network element can request the first target network element's profile from the first routing network element or the NRF network element. Alternatively, the second routing network element can send the second uplink NAS message to the first routing network element, which in turn sends the second uplink NAS message to the first target network element.

[0566] The terminal can also send a third uplink NAS message. For example, the terminal sends a third uplink NAS message carrying a temporary identifier of the second target network element, which is the network element used to process the third uplink NAS message. This third uplink NAS message is received by the first routing network element. Correspondingly, after receiving the third uplink NAS message from the terminal, the first routing network element determines that it does not store the temporary identifier of the second target network element and cannot obtain the profile of the second target network element. Then, the first routing network element can request the profile of the second target network element from the third routing network element or the NRF network element, or it can send the third uplink NAS message to the third routing network element, which in turn sends the third uplink NAS message to the second target network element.

[0567] For details not described here, please refer to the description following step 705 above, and... Figures 11 to 12 As described in the relevant embodiments.

[0568] The step numbers in the flowcharts described in this application are merely examples of the execution flow and do not constitute a restriction on the order in which the steps are executed. There is no strict execution order between steps in the embodiments that do not have temporal dependencies. Not all steps shown in the flowcharts are mandatory; some steps may be deleted or added as needed.

[0569] The above focuses on describing the differences between different embodiments. Apart from the differences, the embodiments can be referred to each other. In addition, different implementations or different examples in the same embodiment can also be referred to each other.

[0570] Based on the above content and the same concept, Figure 14 and Figure 15 This is a schematic diagram of the possible communication devices provided in this application. These communication devices can be used to implement the functions of the first routing network element, the terminal, the second routing network element, the third routing network element, and the NRF network element in the above method embodiments, and therefore can also achieve the beneficial effects of the above method embodiments.

[0571] In this application, the communication device can be as follows: Figure 1 or Figure 6 The terminal shown can also be as follows: Figure 6 The routing network element shown can also be as follows: Figure 1 The NRF network element shown can also be a module (such as a chip) applied to a network element / device.

[0572] like Figure 15As shown, the communication device 1400 includes a processing module 1401 and a transceiver module 1402.

[0573] When the communication device 1400 is used to achieve the above Figures 7 to 12 In any of the method embodiments shown in the figure, the function of the first routing network element is as follows:

[0574] The transceiver module 1402 is used to: receive a first uplink NAS message and first information from the terminal, wherein the first information is used to determine a first target network element, and the first target network element is a network element used to process the first uplink NAS message;

[0575] The transceiver module 1402 is further configured to: send a first uplink NAS message to the first target network element based on the internal identifier of the first target network element; and receive a first downlink NAS message from the first target network element, and send the first downlink NAS message and a temporary identifier of the first target network element to the terminal. For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0576] In one possible implementation, the processing module 1401 is configured to: obtain the internal identifier of the first target network element based on the first information. For example, when obtaining the internal identifier of the first target network element based on the first information, the processing module 1401 is specifically configured to: control the transceiver module 1402 to send a network element discovery request to the NRF network element, the network element discovery request including second information determined based on the first information, the second information being used to determine the first target network element; and control the transceiver module 1402 to receive a network element discovery response from the NRF network element, the network element discovery response including the internal identifier of the first target network element.

[0577] In one possible implementation, before the transceiver module 1402 sends a network element discovery request to the NRF network element, the processing module 1401 is further configured to: determine that the first uplink NAS message does not include a temporary identifier of the first target network element.

[0578] In one possible implementation, before the transceiver module 1402 sends a network element discovery request to the NRF network element, the processing module 1401 is further configured to: determine that the value of the receiver information field in the first uplink NAS message is empty.

[0579] Alternatively, when the processing module 1401 determines that the temporary identifier of the first target network element is not included in the first uplink NAS message, it is specifically used to: determine that the value of the receiver information field in the first uplink NAS message is empty.

[0580] In one possible implementation, the network element discovery response also includes a temporary identifier for the first target network element. In another possible implementation, the network element discovery request is used to instruct the generation of a temporary identifier for the first target network element.

[0581] In one possible implementation, the processing module 1401 is further configured to: save the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element.

[0582] In one possible implementation, when the transceiver module 1402 sends the temporary identifier of the first target network element to the terminal, it is specifically used to: send the temporary identifier of the first target network element to the terminal if there are subsequent uplink NAS messages between the terminal and the first target network element. The processing module 1401 is further used to: determine if there are subsequent uplink NAS messages between the terminal and the first target network element.

[0583] In one possible implementation, the transceiver module 1402 is further configured to: receive a second uplink NAS message from the terminal, the second uplink NAS message including a temporary identifier of the first target network element; the processing module 1401 is further configured to: determine the internal identifier of the first target network element based on the temporary identifier of the first target network element; and the transceiver module 1402 is further configured to: send the second uplink NAS message to the first target network element based on the internal identifier of the first target network element.

[0584] In one possible implementation, the transceiver module 1402 is further configured to: receive a first request from a second routing network element, the first request including a temporary identifier of a first target network element, the first request being used to request an internal identifier of the first target network element; the transceiver module 1402 is further configured to: send the internal identifier of the first target network element to the second routing device.

[0585] In one possible implementation, the transceiver module 1402 is further configured to: receive a third uplink NAS message from the terminal, the third uplink NAS message including a temporary identifier of a second target network element, the temporary identifier of the second target network element including an identifier of a third routing network element, the second target network element being a network element used to process the third uplink NAS message; the transceiver module 1402 is further configured to: send a second request to the third routing network element, the second request including a temporary identifier of the second target network element, the second request being used to request an internal identifier of the second target network element; receive the internal identifier of the second target network element from the third routing network element; and send a third uplink NAS message to the second target network element according to the internal identifier of the second target network element.

[0586] In one possible implementation, the transceiver module 1402 is further configured to: receive a third uplink NAS message from the terminal, the third uplink NAS message including a temporary identifier of the second target network element, the temporary identifier of the second target network element including an identifier of the third routing device; and send a third uplink NAS message to the third routing device according to the identifier of the third routing device.

[0587] When the communication device 1400 is used to achieve the above Figures 7 to 12When the terminal functions in any of the method embodiments shown in the figure:

[0588] The transceiver module 1402 is used to: send a first uplink NAS message and first information, wherein the first information is used to determine a first target network element, and the first target network element is a network element used to process the first uplink NAS message;

[0589] The transceiver module 1402 is used to receive a first downlink NAS message and a temporary identifier of a first target network element. For example, the first downlink NAS message is a response message to the first uplink NAS message.

[0590] In one possible implementation, the processing module 1401 is used to: determine that the temporary identifier of the first target network element is not included in the first uplink NAS message if the temporary identifier of the first target network element is not obtained.

[0591] In one possible implementation, the processing module 1401 is used to: set the value of the receiver information field in the first uplink NAS message to empty if the temporary identifier of the first target network element is not obtained.

[0592] In one possible implementation, the transceiver module 1402 is further configured to: send a second uplink NAS message, the second uplink NAS message including a temporary identifier of the first target network element, the temporary identifier of the first target network element being used for routing the second uplink NAS message.

[0593] In one possible implementation, after the transceiver module 1402 receives the first downlink NAS message and the temporary identifier of the first target network element, the processing module 1401 is further configured to: save the mapping relationship between the temporary identifier of the first target network element and the first information.

[0594] In one possible implementation, after the processing module 1401 saves the mapping relationship between the temporary identifier of the first target network element and the first information, it is further used to: obtain the temporary identifier of the first target network element according to the mapping relationship; the transceiver module 1402 is further used to: send a second uplink NAS message, the second uplink NAS message including the temporary identifier of the first target network element, the temporary identifier of the first target network element being used for routing the second uplink NAS message.

[0595] In one possible implementation, the transceiver module 1402 is further configured to: send a third uplink NAS message, the third uplink NAS message including a temporary identifier of a second target network element, the temporary identifier of the second target network element including an identifier of a third routing network element, the second target network element being a network element used to process the third uplink NAS message; wherein, the identifier of the third routing network element is used to route the third uplink NAS message to the third routing network element, or to request an internal identifier of the second target network element from the third routing network element.

[0596] When the communication device 1400 is used to achieve the above Figures 7 to 12 When the function of the second routing network element in any of the method embodiments shown in the figure is as follows:

[0597] The transceiver module 1402 is configured to: receive a second uplink NAS message from the terminal, the second uplink NAS message including a temporary identifier of a first target network element, the temporary identifier of the first target network element including an identifier of a first routing network element, the first target network element being the network element used to process the second uplink NAS message; the processing module 1401 is configured to: control the transceiver module 1402 to send the second uplink NAS message to the first routing network element according to the identifier of the first routing network element, the first routing network element being used to route the second uplink NAS message to the first target network element. Alternatively,

[0598] The transceiver module 1402 is configured to: receive a second uplink NAS message from a terminal, the second uplink NAS message including a temporary identifier of a first target network element, the temporary identifier of the first target network element including an identifier of a first routing network element, the first target network element being a network element used to process the second uplink NAS message; and send a first request to the first routing network element, the first request including a temporary identifier of the first target network element, the first request being used to request an internal identifier of the first target network element; the transceiver module 1402 is further configured to: receive the internal identifier of the first target network element from the first routing network element, and send the second uplink NAS message to the first target network element. Alternatively, the transceiver module 1402 is further configured to: receive a mapping relationship between the internal identifier and the temporary identifier of the first target network element from the first routing network element; the processing module 1401 is configured to: control the transceiver module 1402 to send the second uplink NAS message to the first target network element according to the mapping relationship.

[0599] When the communication device 1400 is used to achieve the above Figures 7 to 12 When the third routing network element functions in any of the method embodiments shown in the diagram:

[0600] The transceiver module 1402 is configured to: receive a second request from a first routing network element, the second request including a temporary identifier of a second target network element, the second request being used to request an internal identifier of the second target network element; the processing module 1401 is configured to: determine the internal identifier of the second target network element based on the temporary identifier of the second target network element. The transceiver module 1402 is also configured to: send the internal identifier of the second target network element to the first routing network element. Alternatively,

[0601] The transceiver module 1402 is configured to: receive a second request from the first routing network element, the second request including a temporary identifier of the second target network element, the second request being used to request the internal identifier of the second target network element; the processing module 1401 is configured to: determine the mapping relationship between the internal identifier and the temporary identifier of the second target network element based on the temporary identifier of the second target network element. The transceiver module 1402 is also configured to: send the mapping relationship between the internal identifier and the temporary identifier of the second target network element to the first routing network element. Alternatively,

[0602] The transceiver module 1402 is configured to: receive a third uplink NAS message from the first routing network element, wherein the third uplink NAS message includes a temporary identifier of the second target network element, and the temporary identifier of the second target network element includes the identifier of the third routing network element; the second target network element is a network element used to process the third uplink NAS message. The processing module 1401 is configured to: determine the internal identifier of the second target network element based on the temporary identifier of the second target network element; the transceiver module 1402 is further configured to: send the third uplink NAS message to the second target network element based on the internal identifier of the second target network element.

[0603] When the communication device 1400 is used to achieve the above Figures 7 to 12 When the NRF network element functions in any of the method embodiments shown in the figure:

[0604] The transceiver module 1402 is used to: receive a network element discovery request from a first routing network element. The processing module 1401 is used to: determine the temporary identifier and the instance identifier of the first target network element based on the network element discovery request. The transceiver module 1402 is also used to: send the temporary identifier and the instance identifier of the first target network element to the first routing network element.

[0605] In one possible implementation, the network element discovery request is used to instruct the NRF network element to generate a temporary identifier for the first target network element. When determining the temporary identifier of the first target network element, the processing module 1401 specifically generates the temporary identifier for the first target network element if it determines that the network element discovery request includes third information. For example, the third information may include one or more of the following: NAS type, NAS message type, indication to generate a temporary identifier for the first target network element, indication that a downlink NAS message exists in the network, indication that other uplink NAS messages will subsequently exist in the network, a consumer field, and a service name field. The consumer field is the identifier of the first routing network element; the service name field is the service that forwards the NAS message. The third information can be used to instruct the NRF network element to generate a temporary identifier for the first target network element.

[0606] like Figure 15 The image shown is of the apparatus 1500 provided in an embodiment of this application. Figure 15 The device shown can be Figure 14The illustrated device represents one hardware circuit implementation. This device can be applied to the flowchart shown above to perform the functions of the terminal, routing network element, or NRF network element in the method embodiments described above. For ease of explanation, Figure 15 Only the main components of the device are shown.

[0607] Figure 15 The illustrated device 1500 includes a communication interface 1510, a processor 1520, and a memory 1530, wherein the memory 1530 is used to store program instructions and / or data. The processor 1520 may operate in conjunction with the memory 1530. The processor 1520 may execute program instructions stored in the memory 1530. When the instructions or program stored in the memory 1530 are executed, the processor 1520 is used to perform the operations performed by the processing module 1401 in the above embodiments, and the communication interface 1510 is used to perform the operations performed by the transceiver module 1402 in the above embodiments.

[0608] The memory 1530 and the processor 1520 are coupled. The coupling in this embodiment is an indirect coupling or communication connection between devices, units, or modules, and can be electrical, mechanical, or other forms, used for information exchange between devices, units, or modules. At least one of the memories 1530 may be included in the processor 1520.

[0609] In this embodiment, the communication interface can be a transceiver, circuit, bus, module, or other type of communication interface. In this embodiment, when the communication interface is a transceiver, the transceiver can include an independent receiver, an independent transmitter, or a transceiver integrating transceiver functions, or simply a communication interface.

[0610] Device 1500 may further include a communication line 1540. The communication interface 1510, processor 1520, and memory 1530 can be interconnected via the communication line 1540. The communication line 1540 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The communication line 1540 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 15 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0611] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0612] Based on the above content and the same concept, this application provides a computer-readable storage medium storing a computer program or instructions. When the computer program or instructions are executed by a communication device, the method of the terminal, the first routing network element, the second routing network element, the third routing network element, or the NRF network element in the above method embodiments is implemented.

[0613] Based on the above content and the same concept, this application provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are executed by a communication device, they implement the methods of the terminal, the first routing network element, the second routing network element, the third routing network element, or the NRF network element in the above method embodiments.

[0614] The method steps in the embodiments of this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can 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, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a base station or terminal. Of course, the processor and storage medium can also exist as discrete components in the base station or terminal.

[0615] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded and executed on a computer, all or part of the processes or functions of the embodiments of this application are performed. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, a computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0616] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0617] In this application embodiment, "including" can also be replaced with "specifically is", and "including one or more of A, B, and C" can also be replaced with "specifically is one or more of A, B, and C". For example, the first information includes one or more of EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier, which can also be understood as the first information specifically being one or more of EPD, message type, network element type, slice identifier, subnet identifier, and PDU session identifier. That is, the first information is specifically EPD, the first information is specifically message type, the first information is specifically network element type, the first information is specifically a combination of EPD and message type, the first information is specifically a combination of EPD and network element type, the first information is specifically a combination of EPD, message type, and network element type, the first information is specifically a combination of EPD, message type, and slice identifier, etc.

[0618] In this application embodiment, the number of nouns, unless otherwise specified, refers to "singular nouns or plural nouns," that is, "one or more." "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0619] In the embodiments of this application, "send" and "receive" indicate the direction of signal transmission. For example, "send information to XX" can be understood as the destination of the information being XX, which may include direct transmission via the air interface or indirect transmission by other units or modules via the air interface. "Receive information from YY" can be understood as the source of the information being YY, which may include direct reception from YY via the air interface or indirect reception from YY by other units or modules via the air interface. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface. In other words, sending and receiving can occur between devices, such as between access network devices and terminals, or within a device, such as between components, modules, chips, software modules, or hardware modules within the device via a bus, wiring, or interface.

[0620] In the embodiments of this application, "when," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, and are not time-limited, nor do they require the device to perform a judgment action, nor do they imply any other limitations. Unless otherwise specified, "if" and "if" can be substituted, and "when" and "in the case of" can be substituted. "When" and "if" / "if" can be substituted.

[0621] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0622] In this application's embodiments, ordinal numbers such as "first" and "second" are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority, or importance of the multiple objects. For example, "first information" and "second information" refer to two different pieces of information, and do not indicate a difference in priority or importance between the two pieces of information.

[0623] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, Applied to the first routing device side, including: Receive a first uplink non-access stratum (NAS) message and first information from the terminal, wherein the first information is used to determine a first target network element, and the first target network element is a network element used to process the first uplink NAS message; Based on the internal identifier of the first target network element, send the first uplink NAS message to the first target network element; Receive a first downlink NAS message from the first target network element, and send the first downlink NAS message and a temporary identifier of the first target network element to the terminal.

2. The method as described in claim 1, characterized in that, The first information includes one or more of the following: extended protocol identifier, message type, slice identifier, subnet identifier, and protocol data unit session identifier.

3. The method as described in claim 1 or 2, characterized in that, Also includes: The internal identifier of the first target network element is obtained based on the first information.

4. The method as described in claim 3, characterized in that, The step of obtaining the internal identifier of the first target network element based on the first information includes: Send a network element discovery request to a network storage function (NRF) network element. The network element discovery request includes second information, which is determined based on the first information. The second information is used to determine the first target network element. Receive a network element discovery response from the NRF network element, the network element discovery response including the internal identifier of the first target network element.

5. The method according to any one of claims 1-4, characterized in that, Before sending the network element discovery request to the NRF network element, the method further includes: It was determined that the value of the receiver information field in the first uplink NAS message was empty.

6. The method according to any one of claims 1-5, characterized in that, Before sending the network element discovery request to the NRF network element, the method further includes: It is determined that the first uplink NAS message does not include the temporary identifier of the first target network element.

7. The method according to any one of claims 4-6, characterized in that, The network element discovery response also includes a temporary identifier for the first target network element.

8. The method according to any one of claims 4-7, characterized in that, The network element discovery request is used to instruct the generation of a temporary identifier for the first target network element.

9. The method according to any one of claims 1-6, characterized in that, Also includes: Generate a temporary identifier for the first target network element.

10. The method according to any one of claims 1-9, characterized in that, The temporary identifier of the first target network element includes one or more of the following: the identifier of the first routing device, information used to uniquely identify the first target network element on the first routing device, the identifier of the NRF network element, and information used to uniquely identify the first target network element on the NRF network element.

11. The method according to any one of claims 1-10, characterized in that, Also includes: Save the mapping relationship between the internal identifier of the first target network element and the temporary identifier of the first target network element.

12. The method according to any one of claims 1-10, characterized in that, Sending the temporary identifier of the first target network element to the terminal includes: If there are subsequent uplink NAS messages between the terminal and the first target network element, a temporary identifier of the first target network element is sent to the terminal.

13. The method according to any one of claims 1-12, characterized in that, Also includes: Receive a second uplink NAS message from the terminal, the second uplink NAS message including a temporary identifier of the first target network element; Based on the temporary identifier of the first target network element, determine the internal identifier of the first target network element; Based on the internal identifier of the first target network element, the second uplink NAS message is sent to the first target network element.

14. The method according to any one of claims 1-13, characterized in that, Also includes: Receive a first request from a second routing device, the first request including a temporary identifier of the first target network element, the first request being used to request an internal identifier of the first target network element; The internal identifier of the first target network element is sent to the second routing device.

15. The method according to any one of claims 1-14, characterized in that, Also includes: Receive a third uplink NAS message from the terminal, the third uplink NAS message including a temporary identifier of a second target network element, the temporary identifier of the second target network element including an identifier of a third routing device, the second target network element being a network element used to process the third uplink NAS message; Send a second request to the third routing device, the second request including a temporary identifier of the second target network element, the second request being used to request the internal identifier of the second target network element; Receive the internal identifier of the second target network element from the third routing device; The third uplink NAS message is sent to the second target network element based on the internal identifier of the second target network element.

16. The method according to any one of claims 1-14, characterized in that, Also includes: Receive a third uplink NAS message from the terminal, the third uplink NAS message including a temporary identifier of a second target network element, the temporary identifier of the second target network element including an identifier of a third routing device, the second target network element being a network element used to process the third uplink NAS message; The third uplink NAS message is sent to the third routing device based on the identifier of the third routing device.

17. A communication method, characterized in that, Applied to the terminal device side, including: Send a first uplink non-access stratum (NAS) message and first information, wherein the first information is used to determine a first target network element, and the first target network element is a network element used to process the first uplink NAS message; Receive the first downlink NAS message and the temporary identifier of the first target network element.

18. The method as described in claim 17, characterized in that, The first information includes one or more of the following: extended protocol identifier, message type, slice identifier, subnet identifier, and protocol data unit session identifier.

19. The method as described in claim 17 or 18, characterized in that, The temporary identifier of the first target network element includes one or more of the following: the identifier of the first routing device, information on the first routing device used to uniquely identify the first target network element, the identifier of the Network Storage Function (NRF) network element, and information on the NRF network element used to uniquely identify the first target network element; Both the first routing device and the NRF network element are devices used to store the mapping relationship between the temporary identifier and the internal identifier of the first target network element.

20. The method according to any one of claims 17-19, characterized in that, Also includes: If the temporary identifier of the first target network element is not obtained, the value of the receiver information field in the first uplink NAS message is set to empty.

21. The method according to any one of claims 17-20, characterized in that, Also includes: If the temporary identifier of the first target network element is not obtained, it is determined that the temporary identifier of the first target network element is not included in the first uplink NAS message.

22. The method according to any one of claims 17-21, characterized in that, After receiving the first downlink NAS message and the temporary identifier of the first target network element, the method further includes: Send a second uplink NAS message, which includes a temporary identifier of the first target network element. The temporary identifier of the first target network element is used for routing the second uplink NAS message.

23. The method according to any one of claims 17-22, characterized in that, After receiving the first downlink NAS message and the temporary identifier of the first target network element from the first routing device, the method further includes: Save the mapping relationship between the temporary identifier of the first target network element and the first information.

24. The method as described in claim 23, characterized in that, After saving the mapping relationship between the temporary identifier of the first target network element and the first information, the method further includes: Based on the mapping relationship, obtain the temporary identifier of the first target network element; Send a second uplink NAS message, which includes a temporary identifier of the first target network element. The temporary identifier of the first target network element is used for routing the second uplink NAS message.

25. The method according to any one of claims 17-24, characterized in that, Also includes: Send a third uplink NAS message, the third uplink NAS message including a temporary identifier of the second target network element, the temporary identifier of the second target network element including the identifier of the third routing device, the second target network element being the network element used to process the third uplink NAS message; The identifier of the third routing device is used to route the third uplink NAS message to the third routing device, or to request the internal identifier of the second target network element from the third routing device.

26. A communication device, characterized in that, It includes a module for performing the method as described in any one of claims 1 to 16, or includes a module for performing the method as described in any one of claims 17 to 25.

27. A communication device, characterized in that, The device includes a processor and an interface circuit. The interface circuit is used to receive signals from other communication devices besides the communication device and transmit them to the processor, or to send signals from the processor to other communication devices besides the communication device. The processor is used to implement the method as described in any one of claims 1 to 16 through logic circuits or executable code instructions, or the processor is used to implement the method as described in any one of claims 17 to 25 through logic circuits or executable code instructions.

28. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 16, or implement the method as described in any one of claims 17 to 25.

29. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 16, or implement the method as described in any one of claims 17 to 25.

30. A communication system, characterized in that, include: The first routing device and the first target network element; The first routing device is used to implement the method as described in any one of claims 1 to 16; The first target network element is used to receive a first uplink NAS message from the first routing device, and to send a first downlink NAS message to the first routing device.

31. The system as described in claim 30, characterized in that, Also includes: A terminal device; the terminal device is used to implement the method as described in any one of claims 17 to 25.

32. The system as described in claim 30 or 31, characterized in that, Also includes: Network storage device; The network storage function device is used for: Receive a network element discovery request from the first routing device, the network element discovery request including first information, the first information being used to determine the first target network element; A network element discovery response is sent to the first routing device, the network element discovery response including the internal identifier of the first target network element.

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