Session management method and device

Abstract

Provided are a session management method and device, the method comprising: an access network element receiving a first message from a terminal device, the first message comprising an identifier of a first session and a first non-access stratum (NAS) message, the first NAS message being used for requesting to establish or activate the first session corresponding to the identifier; and the access network element sends a second message to the first session management function network element, wherein the second message comprises the first NAS message and the identifier of the terminal device. In the scheme, the network element of the access network can be directly connected with the network element of the first session management function (for example, direct connection based on a servitization interface), the network element of the access network and the network element of the first session management function directly interact the NAS message without AMF transfer, the flexibility of deployment of the network element of the core network can be improved, and the management and control efficiency of the related process of the network session can be improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a session management method and device. Background Art

[0002] At present, in wireless communication systems, the access and mobility management function (AMF) network element serves as the transit of non-access stratum (NAS) signaling. The interaction between terminal devices or access network devices and other core network elements needs to rely on AMF forwarding. The deployment of core network elements is inflexible, resulting in poor flexibility in the network's management and control of protocol data unit (PDU) session-related processes. Summary of the invention

[0003] A session management method and apparatus provided in an embodiment of the present application can realize a distributed connection between access network equipment and core network elements, thereby improving the flexibility of the network in managing and controlling session-related processes.

[0004] In a first aspect, a session management method is provided, which can be applied to an access network network element or a chip in an access network network element. Taking the application of the method to an access network network element as an example, the method includes: the access network network element receives a first message from a terminal device, the first message includes an identifier of a first session and a first non-access layer NAS message, and the first NAS message is used to request to establish or activate a first session corresponding to the identifier; the access network network element sends a second message to a first session management function network element, and the second message includes the first NAS message and the identifier of the terminal device.

[0005] In the above scheme, the access network element can be directly connected to the first session management function element (for example, directly connected based on a service-based interface). The access network element and the first session management function element directly exchange NAS messages without the need for AMF transit, which can improve the flexibility of core network element deployment and improve the efficiency of network session-related process management and control.

[0006] In one possible design, before the access network element sends the second message to the first session management function element, the access network element may also receive a third message from the registration function element, the third message including at least one information, and the registration function element is the registration function element for registering the terminal device. Accordingly, the access network element may send the second message to the first session management function element based on the at least one information.

[0007] In this way, the access network element forwards the first NAS message to the first session management function network element according to at least one information provided by the registration function network element, which can improve the reliability of the solution.

[0008] In one possible design, at least one information includes first information, and the first information is used to indicate that the terminal device is located in an allowed area or is not located in a non-allowed area, or the first information is used to indicate an allowed area and / or a non-allowed area. Accordingly, if the terminal device is located in an allowed area or is not located in a non-allowed area, the access network element sends a second message to the first session management function element.

[0009] In this way, only when the terminal device is located in the allowed area or not in the non-allowed area, the access network element will forward the NAS message sent by the terminal device to the corresponding session management function network element, thereby preventing the NAS message of the terminal device in the non-allowed area from being forwarded to the session management function network element.

[0010] In one possible design, at least one information includes second information; the second information is used to indicate an allowed message type, and accordingly, if the allowed message type includes a message type corresponding to the first NAS message, the access network network element sends the second message to the first session management function network element; or, the second information is used to indicate a non-allowed message type, and accordingly, if the non-allowed message type does not include a message type corresponding to the first NAS message, the access network network element sends the second message to the first session management function network element.

[0011] In this way, the access network element only forwards NAS messages of permitted message types to the session management function network, thereby preventing NAS messages of non-permitted message types from being forwarded to the session management function network element.

[0012] In one possible design, at least one information includes third information, and the third information is used to indicate whether the terminal device is allowed to access. Correspondingly, if the third information is used to indicate that the terminal device is allowed to access, the access network element sends a second message to the first session management function element.

[0013] In this way, only when the terminal device is allowed to access the domain, the access network element will forward the NAS message sent by the terminal device to the corresponding session management function network element, avoiding the NAS message of the terminal device that is not allowed to access from being forwarded to the session management function network element.

[0014] In one possible design, the third message also includes the identifier of the registration function network element, and the second message also includes the identifier of the registration function network element.

[0015] In this way, the access network element provides the identifier of the registration function network element to the first session management function network element.

[0016] In one possible design, the first NAS message is used to request the establishment of a first session corresponding to the identifier, the first NAS message is a session establishment request message, and the first NAS message includes the identifier of the first session. In other words, the method of the embodiment of the present application can be applied to the session establishment scenario.

[0017] In a possible design, in a session establishment scenario, after the access network element receives the first message from the terminal device and before the access network element sends the second message to the first session management function element, the access network element also sends a first request to the selection function element, the first request is used to request the selection of a session management function element for the first session; the access network element receives a first response from the selection function element, the first response includes identification information of the first session management function element. Accordingly, the access network element can send the second message to the first session management function element according to the identification information of the first session management function element.

[0018] In this way, it is possible to select a corresponding session management function network element (ie, the first session management function network element) for the first session, thereby ensuring the reliability of session establishment.

[0019] In one possible design, in a session establishment scenario, before the access network element receives the first message from the terminal device, the access network element may also send an access request message to the registration function network element, and the third message is a response message to the access request message.

[0020] In this way, the terminal device can be connected to the network so as to execute the session establishment process. In addition, carrying at least one information in the response message can save the interaction process, thereby improving the efficiency of session establishment.

[0021] In one possible design, the first NAS message is used to request activation of the first session corresponding to the identifier, and the first NAS message is a service request message or a session activation request message; the first NAS message includes the identifier of the first session. In other words, the method of the embodiment of the present application can be applied to the session activation scenario. It can be understood that the service request scenario requires the activation of the session.

[0022] In one possible design, in a session activation scenario, the access network element can obtain identification information of the first session management function network element, and the access network element sends a second message to the first session management function network element based on the identification information of the first session management function network element.

[0023] Exemplarily, the access network element may send a second request to the terminal context information storage function network element, where the second request is used to query the session management function network element corresponding to the first session; the access network element receives a second response from the terminal context information storage function network element, where the second response includes identification information of the first session management function network element.

[0024] In this way, the access network element can obtain the identification information of the first session management function element from the terminal context information storage function element, thereby improving the reliability of the solution.

[0025] Exemplarily, the first message includes identification information of the first session management function network element; the access network element may obtain the identification information of the first session management function network element from the first message.

[0026] In this way, the terminal device can provide the access network network element with the identification information of the first session management function network element, and the access network network element does not need to query the session management function network element from elsewhere, which can improve the interaction efficiency.

[0027] Of course, the above two methods of determining the first session management function network element are only examples and are not limited thereto.

[0028] In this way, it is possible to determine a corresponding session management function network element (ie, the first session management function network element) for the first session, thereby ensuring the reliability of session activation.

[0029] In one possible design, in a session activation scenario, before the access network element receives the third message from the registration function network element, the access network element may also send an access request message to the registration function network element, where the access request message includes an identifier of the terminal device, and the third message is a response message to the access request message.

[0030] In this way, the terminal device can be connected to the network so as to execute the session activation process. In addition, carrying at least one information in the response message can save the interaction process, thereby improving the efficiency of session establishment.

[0031] In one possible design, after the access network element receives the first message from the terminal device, the access network element sends an access request message to the registration function network element.

[0032] In other words, by sending the first message, the terminal device can trigger the access process and the session activation process at the same time, which can reduce the number of times the terminal device sends messages and save energy consumption of the terminal device.

[0033] In one possible design, before the access network element receives the first message from the terminal device, the access network element receives a fourth message from the terminal device, the fourth message includes a second NAS message, and the second NAS message is used to request access to the network or activate a control plane connection. Correspondingly, the access network element sends an access request message to the registration function element according to the fourth message, and the access request message includes the second NAS message.

[0034] In other words, the terminal device first sends the fourth message to connect the terminal device to the network, and then sends the first message to activate the session after connecting to the network. In this way, in the session activation process, the terminal device does not need to be connected again, which can improve the efficiency of the session activation process.

[0035] In one possible design, the first message includes an identifier of at least one session and at least one NAS message, the at least one NAS message corresponds to the at least one session, the NAS message corresponding to the first session in the at least one session is used to request to establish or activate the first session, and the first session is any one of the at least one session. Accordingly, the access network element sends a second message to the session management function element corresponding to each session.

[0036] In this way, multiple sessions can be established or activated simultaneously, which can further improve the efficiency of session management and control.

[0037] According to a second aspect, a session management method is provided. The method can be applied to a first session management function network element or a chip in the first session management function network element. Taking the application of the method to the first session management function network element as an example, the method includes: the first session management function network element receives a second message from an access network network element, the second message includes a first NAS message and an identifier of a terminal device, and the first NAS message is used to request to establish or activate a first session; the first session management function network element accepts or rejects the first NAS message according to the mobility restriction information of the terminal device.

[0038] In one possible design, the first session management function network element may obtain the mobility restriction information of the terminal device from the registration function network element according to the identifier of the registration function network element, where the registration function network element is the registration function network element where the terminal device is registered.

[0039] In one possible design, the second message also includes an identifier of the registration function network element.

[0040] In one possible design, the first session management function network element can also obtain the terminal context information of the registration function network element from the terminal context information storage function network element based on the terminal context information of the terminal device. The terminal context information storage function network element stores the correspondence between the terminal context information of the registration function network element and the terminal context information of the terminal device.

[0041] In a possible design, the first session management function network element may also obtain the mobility restriction information of the terminal device from the terminal context information storage function network element according to the terminal context information of the terminal device.

[0042] In a possible design, the mobility restriction information may include fourth information, and the fourth information is used to indicate whether the terminal device is in an allowed area or a non-allowed area. Accordingly, when the terminal device is in an allowed area or not in a non-allowed area, the first session management function network element accepts the first NAS message; otherwise, the first session management function network element rejects the first NAS message.

[0043] In a possible design, the mobility restriction information may include fifth information, and the fifth information is used to indicate the allowed area or non-allowed area of ​​the terminal device. Accordingly, the first session management function network element can determine whether the terminal device is located in the allowed area and / or the non-allowed area based on the location information of the terminal device and the fifth information. When the terminal device is located in the allowed area or not in the non-allowed area, the first session management function network element accepts the first NAS message; otherwise, the first session management function network element rejects the first NAS message.

[0044] In one possible design, the second message also includes an identifier of the data network and / or an identifier of the network slice; the fifth information is specifically used to indicate an allowed area or a non-allowed area of ​​a terminal device corresponding to the data network and / or the network slice.

[0045] In a possible design, the mobility restriction information includes sixth information, and the sixth information is used to indicate an allowed wireless access technology or an unallowed wireless access technology. Accordingly, when the wireless access technology of the access network element belongs to an allowed wireless access technology, or the wireless access technology of the accessed network element does not belong to an unallowed wireless access technology, the first session management function network element accepts the first NAS message; otherwise, the first NAS message is rejected.

[0046] On the third aspect, a session management method is provided, which can be applied to a registration function network element or a chip in a registration function network element. Taking the application of the method to a registration function network element as an example, the method includes: the registration function network element receives an access request message from an access network network element, and the access request message is used to request that a terminal device be connected to the registration function network element (or network); the registration function network element sends a third message to the access network network element, and the third message includes at least one information, and the at least one information is used by the access network network element to determine whether to forward the first NAS message.

[0047] In a possible design, the at least one information includes but is not limited to at least one of the following:

[0048] First information, the first information is used to indicate that the terminal device is located in the allowed area or is not located in the non-allowed area, or the first information is used to indicate the allowed area and / or the non-allowed area;

[0049] second information, the second information is used to indicate an allowed message type or an unallowed message type;

[0050] The third information is used to indicate whether the terminal device is allowed to access.

[0051] In one possible design, the registration function network element can also determine the allowed message type or the non-allowed message type based on the location information of the terminal device.

[0052] In one possible design, the registration function network element may also send mobility restriction information of the terminal device to the first session management function network element.

[0053] The mobility restriction information includes at least one of the following:

[0054] Fourth information, used to indicate whether the terminal device is in an allowed area or a non-allowed area;

[0055] The fifth information is used to indicate the allowed area or non-allowed area of ​​the terminal device.

[0056] The sixth information is used to indicate an allowed wireless access technology or an unallowed wireless access technology.

[0057] In a possible design, the third message also includes an identifier of the registration function network element. Alternatively, the registration function network element sends the identifier of the registration function network element to the terminal context information storage function network element.

[0058] In one possible design, the third message is a response message to the access request message.

[0059] In a fourth aspect, a session management method is provided. The method can be applied to a terminal device or a chip in a terminal device. Taking the method applied to a terminal device as an example, the method includes: the terminal device generates a first message; the terminal device sends the first message to an access network element; wherein the first message includes an identifier of at least one session and at least one NAS message, and the at least one NAS message corresponds to at least one session one-to-one, and the NAS message corresponding to each session in the at least one session is used to request to establish or activate each session.

[0060] In one possible design, the first message also includes identification information of at least one session management function network element, the identification information of at least one session management function network element corresponds one-to-one to at least one session, and each session management function network element in the at least one session management function network element is responsible for managing the session corresponding to the identification information of each session management function network element.

[0061] In one possible design, the terminal device may also receive identification information of each session management function network element from each session management function network element in at least one session management function network element.

[0062] In one possible design, before the terminal device sends the first message, the terminal device may also send a fourth message to the access network element, where the fourth message includes a second NAS message, and the second NAS message is used to request access to the network or activate a control plane connection.

[0063] According to a fifth aspect, a communication device is provided, comprising a module, a unit or a means for executing a method according to the first aspect or any possible design of the first aspect.

[0064] Exemplarily, the device may include:

[0065] A transceiver unit is used to receive a first message from a terminal device, the first message including an identifier of a first session and a first non-access layer NAS message, the first NAS message being used to request establishment or activation of a first session corresponding to the identifier; and send a second message to a first session management function network element, the second message including the first NAS message and the identifier of the terminal device.

[0066] According to a sixth aspect, a communication device is provided, comprising a module, a unit or a means for executing a method as in the second aspect or any possible design of the second aspect.

[0067] Exemplarily, the device may include:

[0068] A transceiver unit, configured to receive a second message from an access network element, wherein the second message includes a first NAS message and an identifier of a terminal device, and the first NAS message is used to request to establish or activate a first session;

[0069] A processing unit is used to accept or reject the first NAS message according to the mobility restriction information of the terminal device.

[0070] In a seventh aspect, a communication device is provided, comprising a module, a unit or a means for executing a method as in the third aspect or any possible design of the third aspect.

[0071] Exemplarily, the device may include:

[0072] A transceiver unit is used to receive an access request message from an access network element, where the access request message is used to request that the terminal device be connected to a registration function network element (or network) where the device is located; and send a third message to the access network element, where the third message includes at least one information, and the at least one information is used by the access network element to determine whether to forward the first NAS message.

[0073] In an eighth aspect, a terminal device is provided, comprising a module, a unit or a means for executing the method in the fourth aspect or any possible design of the fourth aspect.

[0074] Exemplarily, the terminal device may include:

[0075] A processing unit, configured to generate a first message;

[0076] A transceiver unit, used to send a first message to an access network element; wherein the first message includes an identifier of at least one session and at least one NAS message, the at least one NAS message corresponds to at least one session, and the NAS message corresponding to each session in the at least one session is used to request to establish or activate each session.

[0077] In the ninth aspect, a communication device is provided, comprising: a processor, the processor being coupled to a memory, the memory being used to store programs or instructions, and when the program or instructions are executed by the processor, the communication device executes the method in the first aspect or any possible design of the first aspect, the second aspect or any possible design of the second aspect, the third aspect or any possible design of the third aspect, or the fourth aspect or any possible design of the fourth aspect.

[0078] In the tenth aspect, a computer-readable storage medium is provided, which stores a computer program or instruction. When the computer program or instruction is executed by a communication device, the method described in the first aspect or any possible design of the first aspect, the second aspect or any possible design of the second aspect, the third aspect or any possible design of the third aspect, or the fourth aspect or any possible design of the fourth aspect is implemented.

[0079] In the eleventh aspect, a chip is provided, which includes a processor for executing program instructions in a storage device to perform a method as described in the first aspect or any possible design of the first aspect, the second aspect or any possible design of the second aspect, the third aspect or any possible design of the third aspect, or the fourth aspect or any possible design of the fourth aspect.

[0080] In the twelfth aspect, a computer program product comprising instructions is provided. The computer program product stores instructions that, when executed on a computer, cause the computer to execute a method as described in the first aspect or any possible design of the first aspect, the second aspect or any possible design of the second aspect, the third aspect or any possible design of the third aspect, or the fourth aspect or any possible design of the fourth aspect.

[0081] In the thirteenth aspect, a communication system is provided, comprising the communication device described in the fifth aspect, the communication device described in the sixth aspect, the communication device described in the seventh aspect, and the communication device described in the eighth aspect.

[0082] For the technical effects that can be achieved by the above-mentioned second to thirteenth aspects, please refer to the description of the technical effects that can be achieved by the corresponding design scheme in the above-mentioned first aspect, and this application will not repeat them here. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 This is a schematic diagram of the network architecture of the 5G communication system;

[0084] Figure 2 An example diagram of the process of establishing a PDU session;

[0085] Figure 3 This is an example diagram of the business request process;

[0086] Figure 4 A schematic diagram of a network architecture of a communication system applicable to an embodiment of the present application;

[0087] Figure 5 A flowchart of a session management method provided in an embodiment of the present application;

[0088] Figure 6 A flowchart of a network element selection method provided in an embodiment of the present application;

[0089] Figure 7 A flowchart of a session establishment method provided in an embodiment of the present application;

[0090] Figure 8 A flowchart of a service request method provided in an embodiment of the present application;

[0091] Fig. 9 A flowchart of a session management method provided in an embodiment of the present application;

[0092] Fig.10 A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0093] Fig.11 A schematic diagram of the structure of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0094] See also Figure 1, is a network architecture diagram of the fifth generation (5th Generation, 5G) communication system. The network functions and entities included in the system mainly include: terminal equipment (user equipment, UE), radio access network ((radio) access network, (R) AN) network element, user plane function (UPF) network element, data network (Data Network, DN), access and mobility management function (access and mobility management function, AMF) network element, session management function (session management function, SMF) network element, policy control function (policy control function, PCF) network element, application function (application function, AF) network element, network slice selection function (network slice selection function, NSSF) network element, authentication server function (authentication server function, AUSF) network element and unified data management (unified data management, UDM) network element, network exposure function (network exposure function, NEF) network element, network repository function (network repository function, NRF) network element, unified data storage function (unified data repository, UDR) network element, etc.

[0095] It can be understood that in this document, for the sake of ease of description, the name of each network function or entity can be represented by its English abbreviation. For example, the session management function network element can be represented by SMF or SMF network element.

[0096] Figure 1 The interaction relationship between network functions and entities and the corresponding interfaces are shown in the figure. For example, UE and AMF can interact through the N1 interface, and (R)AN and AMF can interact through the N2 interface. The interaction message is called N2 message. The interfaces between network elements such as AMF, SMF, PCF, AF, NSSF, AUSF, UDM, and UDR are implemented in the form of service-oriented interfaces.

[0097] UE, (R)AN, UPF and DN are generally referred to as data plane network functions and entities. The user's data traffic can be transmitted through the PDU session (Protocol Data Unit Session) established between UE and DN, and the transmission will pass through the two network function entities (R)AN and UPF; the other parts are called control plane network functions and entities, which are mainly responsible for authentication and authorization, registration management, session management, mobility management and policy control, so as to achieve reliable and stable transmission of user layer traffic. The user plane is used to carry business data, and the control plane is used to carry signaling messages.

[0098] UE: It can also be called terminal, user equipment, mobile station, mobile terminal, etc. Terminal devices can be widely used in various scenarios, for example, device-to-device (D2D), vehicle to everything (V2X) communication, machine-type communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wear, smart transportation, smart city, etc. The terminal device can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a wearable device, a vehicle, a drone, a helicopter, an airplane, a ship, a robot, a robotic arm, a smart home device, etc. In vehicle networking communication, the communication terminal uploaded by the vehicle is a terminal device, and the roadside unit (RSU, Road Side Unit) can also be a terminal device. The embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal device.

[0099] (R)AN: sometimes also called access network equipment or access network node or (R)AN node or (R)AN entity or access node or (R)AN network element, etc., used to help terminal devices achieve wireless access.

[0100] Access network equipment such as a base station (BS), or a base station and a wireless resource management device for controlling the base station, etc. The base station may include an evolved NodeB (NodeB or eNB or e-NodeB, evolved Node B) in a long term evolution (LTE) system or an advanced long term evolution (LTE-A), or may also include a next generation node B (next generation node B, gNB) or a next generation evolved node B (next generation evolved nodeB, ng-eNB), en-gNB (enhanced next generation node B, gNB) in a fifth generation mobile communication technology (the 5th generation, 5G) new radio (new radio, NR) system: an enhanced next generation base station; it may also include a centralized unit (centralized unit, CU) and a distributed unit (distributed unit, DU) in a cloud access network (cloud radio access network, Cloud (R) AN) system, etc., which is not limited in the embodiments of the present application.

[0101] In one possible scenario, multiple (R)AN nodes collaborate to assist the terminal in achieving wireless access, and different (R)AN nodes respectively implement part of the functions of the base station. For example, the (R)AN node can be a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU) or a remote radio head (RRH).

[0102] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the O(R)AN system, CU may also be called O-CU (open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, CU, CU-CP, CU-UP, DU and RU are described as examples in this application. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0103] AMF: Mainly responsible for signaling processing, such as access control, mobility management, attachment and detachment, and gateway selection. When AMF provides services for a session in a terminal device, it will provide control plane storage resources for the session to store the session identifier, the SMF identifier associated with the session identifier, etc.

[0104] SMF: responsible for user plane network element selection, user plane network element redirection, Internet protocol (IP) address allocation, bearer establishment, modification and release, and QoS control.

[0105] UPF: Responsible for forwarding and receiving user data in terminal devices. It can receive user data from the data network and transmit it to the terminal device through the access network device; UPF can also receive user data from the terminal device through the access network device and forward it to the data network. The transmission resources and scheduling functions that provide services to terminal devices in UPF are managed and controlled by SMF.

[0106] NEF: Mainly supports secure interaction between 3GPP networks and third-party applications.

[0107] Application Function (AF): mainly supports interaction with the 3GPP core network to provide services, such as influencing data routing decisions, policy control functions or providing some third-party services to the network side.

[0108] PCF: Responsible for policy control decisions, providing policy rules for control plane functions, and flow-based charging control functions.

[0109] NSSF: Mainly responsible for network slice selection, determining the network slice instance that the UE is allowed to access based on the UE's slice selection auxiliary information, contract information, etc.

[0110] UDM: Mainly responsible for UE subscription data management, including storage and management of UE identification, UE access authorization, etc.

[0111] AUSF: supports 3GPP and non-3GPP access authentication.

[0112] NRF: Supports registration and discovery of network functions.

[0113] UDR: Stores and retrieves contract data used by UDM and PCF.

[0114] certainly, Figure 1 The network elements in the figure are only some examples, and other network elements may be included in practice.

[0115] from Figure 1 It can be seen that the access and mobility management function (AMF) serves as the transit of non-access stratum (NAS) signaling, and the interaction between terminal devices or access network devices and other core network elements needs to rely on AMF forwarding.

[0116] The following takes the PDU session establishment process and service request process as examples:

[0117] See also Figure 2 , which is an example diagram of the PDU session establishment process, includes the following steps:

[0118] S201, UE->AN->AMF: A NAS message is sent from the UE to the AMF, which may include: single network slice selection information (S-NSSAI(s)), data network name (DNN), PDU session ID, request type, old PDU session ID, N1 session management (SM) container (the container includes PDU Session Establishment Request).

[0119] Specifically, to establish a new PDU session, the UE generates a new PDU session ID. The UE initiates the UE Request PDU Session Establishment process by passing an N1 SM container containing a NAS message of PDU Session Establishment Request. PDU Session Establishment Request may include the requested PDU type (Request PDU Type), the requested service and session continuity (SSC) mode (Requested SSC mode), the protocol configuration options (ProtocolConfiguration Options), and the session management PDU data network request container (SM PDU DN RequestContainer).

[0120] S202. AMF selects SMF and allocates SMF to manage PDU session.

[0121] There are two types of SMF selection: AMF contains available SMF information (such as local configuration); when there is no available SMF information, SMF selection is performed through the SMF selection function.

[0122] S203, AMF->SMF: AMF sends a PDU session create context request (SMF Nsmf_PDUSession_CreateSMContext Request) message.

[0123] If AMF and SMF have no association for the PDU Session ID provided by the UE (such as when the Request Type indicates an initial request (Initial Request)), AMF calls Nsmf_PDUSession_CreateSMContext Request; if AMF has already associated with SMF for the PDU Session ID provided by the UE (such as when the Request Type indicates an existing PDU session (Existing PDU Session)), AMF will call the PDU session update context request (Nsmf_PDUSession_UpdateSMContext Request).

[0124] S204, SMF<->UDM: SMF subscribes to data from UDM.

[0125] S205. According to the request received in S203, SMF sends a PDU session create context response (Nsmf_PDUSession_CreateSMContext Response) or a PDU session update context response (Nsmf_PDUSession_UpdateSMContext Response) to AMF.

[0126] S206: The network performs secondary auxiliary authentication / authentication.

[0127] S206 is an optional step, and S207a may be directly executed after S205 is executed.

[0128] S207a. SMF selects PCF.

[0129] S207b, SMF<->PCF: establish a session management policy.

[0130] S208. SMF selects UPF.

[0131] S209, SMF<->PCF: SMF can execute the Session Management Policy Modification process to report some events to the previously subscribed PCF.

[0132] S209 is an optional step, and S210 may be directly executed after S208 is executed.

[0133] S210, SMF<->UPF, N4 Session Establishment process. If RequestType is Initial Request, SMF initiates N4 Session Establishment process, otherwise initiates N4 Session Modification process.

[0134] S211. SMF->AMF: N1N2 message transmission (Namf_Communication_N1N2MessageTransfer).

[0135] The message can include: PDU Session ID; Access Type; N2 SM information (PDUSession ID, QFI (s), QoS Profile (Profile (s)), CN Tunnel Info, S-NSSAI, Session-AMBR, PDU Session Type); N1 SM container (PDU Session Establishment Accept (QoSRule (s), selected SSC mode, S-NSSAI, allocated IPv4 address,interfaceidentifier,Session-AMBR,selected PDU Session Type)).

[0136] The N2 SM information carries the information forwarded by the AMF to the (R)AN. The CN Tunnel Info corresponds to the core network address of the N3 tunnel (Tunnel) of the PDUSession, the QoS profile and the corresponding QFI, and the PDU Session ID is used to indicate to the UE the association between the AN resources and the PDU Session, and the association between the PDU Session and the S-NSSAI and DNN.

[0137] The N1 SM container contains the information provided by the AMF to the UE, including PDU Session Establishment Accept.

[0138] S212. AMF->(R)AN: N2 PDU Session Request.

[0139] The request may include N2 SM information, NAS message (PDU Session ID, N1 SMcontainer (PDU Session Establishment Accept)).

[0140] The AMF sends a NAS message containing the PDU Session ID and PDU Session Establishment Accept for the UE, and the N2 SM information received from the SMF in the N2 PDU Session Request to the (R)AN. The N2 SM information contains the CN Tunnel Info.

[0141] S213, (R)AN->UE: the (R)AN initiates an AN-specific signaling exchange with the UE, which is related to the information received from the SMF.

[0142] S214. (R)AN->AMF: N2 PDU Session Response.

[0143] The response may include PDU Session ID, cause, N2 SM information (PDUSession ID, AN Tunnel Info, List of accepted / rejected QFI(s), etc. Among them, AN Tunnel Info corresponds to the access network address of the N3 Tunnel of the PDU session.

[0144] S215, AMF->SMF: Nsmf_PDUSession_UpdateSMContext Request.

[0145] The request may include N2 SM information and Request Type. The AMF forwards the N2SM information received from the (R)AN to the SMF.

[0146] S216, SMF<->UPF: N4 Session Modification process.

[0147] SMF sends an N4 Session Modification Request to UPF, and SMF provides UPF with AN Tunnel info and corresponding forwarding rules. UPF sends an N4 Session Modification Response to SMF.

[0148] S217, SMF->AMF: Nsmf_PDUSession_UpdateSMContext Response (Cause).

[0149] After this, SMF can subscribe to UE mobility event notifications from AMF by calling the Namf_EventExposure_Subscribe service operation. For local area data network (LADN), SMF subscribes to event notifications of UE moving into or out of the LADN service domain. AMF forwards the relevant events subscribed by SMF.

[0150] It can be seen from the above steps S201 to S203, S205, S211 to S212, S214 to S215 that the interaction between (R)AN and SMF depends on AMF transit.

[0151] See also Figure 3 , is an example diagram of the business request process, including the following steps:

[0152] S301, UE->AN: Access network message (AN Message).

[0153] The message may include: access network parameters (AN parameters), service request (Service Request). The Service Request may include:

[0154] List of PDU Sessions to be activated (List Of PDU Sessions To Be Activated), List Of Allowed PDU Sessions (List Of Allowed PDU Sessions), security parameters, PDU Session status, 5G-system architecture evolution temporary mobile identity (system architecture evolution-TMSI, S-TMSI).

[0155] If the service request is triggered by user data transmission, the UE needs to reactivate the PDU session and provide a list of PDU sessions to be activated. If it is only triggered by signaling reasons, no PDU session is required. The PDU session status (PDU Sessionstatus) identifies all available PDU sessions in the UE. If the UE is not in the LADN area, the UE should not trigger the PDU session request process corresponding to the LADN. For UEs in the connected (CM-CONNECTED) state, the Service Request only needs to include a list of PDU sessions to be activated and a list of allowed PDU sessions. For the NG-(R)AN scenario, the AN parameters include 5G-S-TMSI, the selected PLMN identifier (Selected PLMN ID) and the establishment cause (Establishment cause).

[0156] Among them, 5G-S-TMSI is a shortened form of 5G-globally unique temporary identity (GUTI). The introduction of 5G-S-TMSI is to make the air interface signaling message smaller and improve the air interface efficiency.

[0157] 5G-GUTI: The purpose of using 5G-GUTI in the 5G system is to reduce the use of UE's permanent identification in communications and improve security.

[0158] 5G-GUTI consists of two parts: 1) The first part GUAMI indicates which AMF allocates the 5G-GUTI, 2) The second part 5G-TMSI indicates the unique identifier of the UE within the AMF.

[0159] S302, AN->AMF: N2 message, including N2 parameters and service request.

[0160] For the NG-(R)AN scenario, the N2 parameters include 5G-S-TMSI, Selected PLMN ID, Location information and Establishment cause, and UEContext Request.

[0161] If the UE is in CM-IDLE state, the (R)AN obtains the 5G-GUTI in the RRC process. The (R)AN selects the AMF based on the 5G-GUTI. The location information is related to the cell where the UE resides. Based on the PDU Session status, the AMF initiates the PDU Session Release process in the network to release the PDUs marked as available by the UE.

[0162] S303. If the Service Request is not sent with integrity protection or the integrity protection check fails, the AMF initiates the NAS authentication / security process. If the UE in the CM-IDLE state triggers the service request only to establish a signaling connection, after successfully establishing the signaling connection between the network and the UE, steps S304-S310 and steps S313-S320 are skipped.

[0163] S304, AMF->SMF: Nsmf_PDUSession_UpdateSMContext Request.

[0164] The request may include: PDU Session IDs, Operation Type, UE location information, Access Type, RAT Type, UE presence in LADN service area, and Indication of Access Type can be changed.

[0165] AMF determines the PDU sessions to be reactivated and sends a Nsmf_PDUSession_UpdateSMContext request to the SMF related to these PDU sessions, and marks the reason as creating resources for the user plane. Nsmf_PDUSession_UpdateSMContext is called in the following cases: If the UE identifies the List Of PDUSessions To Be Activated in the service request information; This process is triggered by the SMF, but the PDU session identified by the UE is different from the PDU session that triggered the process, and the AMF decides which PDU sessions will be activated. This process is triggered by the SMF, but the current UE location is outside the legal area provided by the SMF in the N2 information, and the AMF decides which PDU sessions will be activated.

[0166] AMF can establish a new NAS signaling connection by receiving a Service Request, triggering the release of the old NAS signaling connection. For a PDU session marked as to be reactivated, AMF requests SMF to activate the PDU session immediately; for a PDU session marked as activating the N3 user plane, if it is not in the list of PDU sessions to be reactivated, AMF requests SMF to activate the PDU session.

[0167] S305. SMF establishes a policy association with PCF and selects UPF.

[0168] S306-S310, SMF configures the selected UPF.

[0169] S311, SMF->AMF:Nsmf_PDUSession_UpdateSMContext Response.

[0170] The response includes: N2 SM information, N1 SM Container, Cause. Among them, N2 SMinformation includes: PDU Session ID, QFI(s), QoS profile(s), CN N3 Tunnel Info, S-NSSAI, User Plane Security Enforcement, UE Integrity Protection Maximum Data Rate, redundancy sequence number (RSN), PDU Session Pair ID.

[0171] S312, AMF->(R)AN: N2 request (N2 Request).

[0172] The request includes: N2 SM information received from SMF, security context, Mobility Restriction List, Aggregate Maximum Bit Rate (AMBR), UE-Slice Maximum Bit Rate (MBR) list (List of UE-Slice-MBR(s)), MM NAS service acceptance (Service Accept), list of recommended cells / TAs / NG-(R)AN nodeidentifiers, UE Radio Capability, Core Network Assistance Information, Tracing Requirements, and UE Radio Capability ID.

[0173] S313, (R)AN->UE: NG-(R)AN performs RRC connection reconfiguration.

[0174] Through steps S302 to S304, S311 to S312, etc., the interaction between (R)AN and SMF relies on AMF transit. In order to solve the problem that the deployment of the core network network elements is inflexible, resulting in poor flexibility in the control of PDU session-related processes, a technical solution of the embodiment of the present application is provided, which can realize a distributed connection between access network equipment and core network network elements, thereby improving the flexibility of the network's control over PDU session-related processes.

[0175] The embodiments of the present application can be applied to wireless mobile cellular networks, including sixth generation (6G) mobile communication systems and their evolution systems.

[0176] See also Figure 4, which is a schematic diagram of a network architecture of a communication system applicable to an embodiment of the present application, and the network architecture may include some or all of the following multiple devices or network elements: terminal equipment, access network equipment, registration function network element, SMF network element (SMF for short), UPF network element (UPF for short), PCF network element (PCF for short), short message service function (SMSF) network element (SMSF for short), UDM network element (UDM for short), selection function network element and terminal context information storage function network element.

[0177] Among them, there are interfaces between the access network equipment and the registration function network element, SMF, UPF, PCF, SMSF, selection function network element, and terminal context information storage function network element to achieve distributed connection and flexible deployment of core network elements. For example, if the network architecture is a network architecture after the introduction of (R)AN service, the interfaces between the access network equipment and the registration function network element, SMF, UPF, PCF, SMSF, selection function network element, and terminal context information storage function network element can all be service-oriented interfaces.

[0178] Registration function network element: used to provide access management function or registration management function for users (or terminal devices). The registration function network element can also be called access management function network element. In a possible implementation, the registration function network element is AMF.

[0179] Selecting functional network element: used to select core network elements for terminal devices. Core network elements in the network can be registered to selecting functional network elements, and then the selecting functional network element can select target core network elements for the terminal device from the registered core network elements. The selecting functional network element can obtain the contract data of the terminal device from the UDM network element, and then select the target core network element for the terminal device based on the core network element registration information and the contract data. The selecting functional network element can also be called the network element selecting functional network element. In one possible implementation, the selecting functional network element is NRF.

[0180] Terminal context information storage function network element: used to store the context information of the terminal device (UE contextinfomation), including the context information generated when other core network elements manage the terminal device. For example, the terminal context information storage function network element is used to store the correspondence between the temporary identifier and the permanent identifier of the terminal device. Among them, after the registration function network element generates or obtains the correspondence between the temporary identifier and the permanent identifier of the terminal device, the correspondence between the temporary identifier and the permanent identifier of the terminal device can be stored in the terminal context information storage function network element, and the terminal context information storage function network element can also be called an identifier storage function network element. For another example, the terminal context information storage function network element is used to store session identifier information and the identifier information of the session management function network element responsible for managing the session. In one possible implementation, the terminal context information storage function network element is a UDR or an unstructured data storage function (UDSF).

[0181] Figure 4 For other network elements in the network, please refer to the above introduction and will not be repeated here.

[0182] See also Figure 5 , is a flow chart of a session management method provided in an embodiment of the present application, the method is applied to Figure 4 Taking the network architecture shown as an example, the method includes steps S501 to S503.

[0183] S501. A terminal device sends a first message, and a (R)AN receives the first message. The first message includes an identifier of a first session and a first NAS message.

[0184] The first message may be an access network (AN) message.

[0185] The first NAS message is related to the first session. For example, the first NAS message is used to request the establishment of the first session. In other words, the embodiment of the present application can be applied to the session establishment scenario; or the first NAS message is used to request the activation of the first session. In other words, the embodiment of the present application can be applied to the session activation scenario (such as a service request scenario, where the session needs to be activated).

[0186] The first session may be a PDU session, a computing session, or an artificial intelligence (AI) session, etc., which is not limited in this application. Among them, a computing session is a session related to a computing task, and an AI session is a session related to an AI task. For ease of description, this article mainly takes the PDU session as an example.

[0187] It can be understood that the (R)AN may not parse (or perceive) the content of the NAS message, so the first message includes the identifier of the first session, which allows the (R)AN to determine that the first NAS message is related to the first session, and then determine that the first NAS message needs to be forwarded to the SMF that manages the first session (or the SMF corresponding to the first session). For ease of expression, the SMF that manages the first session is referred to as the first SMF hereinafter.

[0188] In some embodiments, the RAN may directly forward the first NAS message to the first SMF (for example, executing step S502). In other embodiments, the (R)AN may first determine whether it is possible (or capable or necessary) to forward the first NAS message to the SMF, and when it is determined that it is possible (or capable or necessary) to forward the first NAS message to the SMF, it may then forward the first NAS message to the first SMF (for example, executing step S502).

[0189] In one possible implementation, when one or more of the following conditions are met, the (R)AN may (or is able to or needs to) forward the first NAS message to the first SMF.

[0190] (1) The terminal device is located in the allowed area and / or not in the non-allowed area;

[0191] In one possible example, the allowed area and / or the non-allowed area is a service restriction area (Service Area Restriction) in the mobility restriction information (MobilityRestrictions). When the terminal device is in the allowed area, the terminal device is allowed to initiate PDU session-related services. When the terminal device is in the non-allowed area, the terminal device is not allowed to initiate PDU session-related services. Therefore, only when the terminal device is located in the allowed area and / or is not located in the non-allowed area, the terminal device is allowed to initiate PDU session-related services, and thus the (R)AN can forward the first NAS message to the first SMF to execute the relevant processes of the first session (such as the establishment process or activation process of the first session).

[0192] In specific implementation, (R)AN can determine whether the terminal device is located in an allowed area or a non-allowed area based on the first information. The first information can directly indicate the result of whether the terminal device is located in an allowed area or a non-allowed area, for example, the first information indicates that the terminal device is located in an allowed area or not in a non-allowed area; or, the first information can indicate an allowed area and / or a non-allowed area, and (R)AN determines whether the terminal device is located in an allowed area or a non-allowed area based on the location information of the terminal device and the first information.

[0193] In another possible example, the service restriction area distinguishes DNN / S-NSSAI. When the terminal device is in the allowed area corresponding to DNN / S-NSSAI, the terminal device is allowed to initiate a session corresponding to DNN / S-NSSAI. When the terminal device is in the non-allowed area corresponding to DNN / S-NSSAI, the terminal device is not allowed to initiate a session corresponding to DNN / S-NSSAI. The first message includes session attribute information such as DNN / S-NSSAI. Therefore, only when the terminal device is located in the allowed area corresponding to DNN / S-NSSAI and / or is not located in the non-allowed area, the terminal device is allowed to initiate a session corresponding to DNN / S-NSSAI, and thus the (R)AN can forward the first NAS message to the first SMF to execute the relevant processes of the first session (such as the establishment process or activation process of the first session).

[0194] In specific implementation, (R)AN can determine whether the terminal device is located in the allowed area (allowed area) or non-allowed area (non-allowed area) corresponding to DNN / S-NSSAI based on the first information. Among them, the first information can directly indicate the result of whether the terminal device is located in the allowed area or non-allowed area corresponding to DNN / S-NSSAI, for example, the first information indicates that the terminal device is located in the allowed area corresponding to DNN / S-NSSAI or is not located in the non-allowed area; or, the first information can indicate the allowed area and / or non-allowed area corresponding to DNN / S-NSSAI, and (R)AN determines whether the terminal device is located in the allowed area or non-allowed area corresponding to DNN / S-NSSAI based on the location information of the terminal device and the first information.

[0195] (2) The allowed message types include the message type corresponding to the first NAS message (or the message type corresponding to the first NAS message is an allowed message type), or the non-allowed message types do not include the message type corresponding to the first NAS message (or the message type corresponding to the first NAS message is not a non-allowed message type). In other words, the (R)AN may forward NAS messages of the allowed message types but not forward NAS messages of the non-allowed message types.

[0196] The allowed message type may specifically be an allowed NAS message type. The non-allowed message type may specifically be a non-allowed NAS message type, which is not limited in this application.

[0197] The message types of NAS messages include, for example, but are not limited to, session management non-access layer messages (SM NAS messages), policy non-access layer messages (Policy NAS messages), etc. The allowed message types and / or the disallowed message types can be set according to the requirements, for example, SM NAS messages are allowed message types, and Policy NAS messages are not allowed message types, or SM NAS messages are not allowed message types, and Policy NAS messages are allowed message types, etc., and the embodiments of the present application do not make specific limitations.

[0198] In specific implementation, the (R)AN may determine whether the message type corresponding to the first NAS message is an allowed message type or an unallowed message type based on the second information. The second information may directly indicate whether the message type corresponding to the first NAS message is an allowed message type or an unallowed message type, for example, the second information indicates that the message type corresponding to the first NAS message is an allowed message type or the message type corresponding to the first NAS message is not an unallowed message type; or, the second information may indicate an allowed message type and / or an unallowed message type, and the (R)AN determines whether the message type corresponding to the first NAS message is an allowed message type or an unallowed message type based on the allowed message type and / or the unallowed message type.

[0199] Optionally, the first message includes a message type of the first NAS message.

[0200] In some embodiments, the allowed message type and / or the disallowed message type may be associated with the allowed area and / or the non-allowed area. The (R)AN or AMF may determine the allowed message type or the non-allowed message type based on the location information of the terminal device. For example, when the (R)AN or AMF determines that the terminal device is in the non-allowed area based on the location information of the terminal device, the allowed area and / or the non-allowed area, the SM NAS message is determined to be an allowed message type, and the Policy NAS message is determined to be a non-allowed message type, that is, the (R)AN can forward the SM NAS message to the SMF, and the (R)AN cannot forward the Policy NAS message to the SMF. Of course, this is just an example, and is not limited to this.

[0201] (3) The terminal device is allowed to access.

[0202] The terminal device is allowed to access, which may refer to the terminal device being allowed to access the network or being allowed to access the AMF or being allowed to access other network elements. The terminal device is allowed to access may be replaced by the terminal device being allowed to establish a session service.

[0203] In one implementation, the (R)AN determines whether the terminal device is allowed to access based on the third information. The third information can directly indicate the result of whether the terminal device is allowed to access, for example, the third information indicates that the terminal device is allowed to access. Alternatively, the third information is reference information for determining whether the terminal device is allowed to access. Exemplarily, the third information may include radio access technology (RAT) restriction information, and the RAT restriction information is used to indicate the radio access technology that the terminal device is allowed to use when accessing the network, such as 3GPP access. The (R)AN can determine whether the terminal device is allowed to access based on the third information and the radio access technology used by the terminal device (for example, the terminal device accesses through the (R)AN, and the radio access technology corresponding to the (R)AN is 3GPP access). Of course, the RAT restriction information here is only an example, and the actual third information may also include other content, such as an allowed area and / or a non-allowed area (the terminal device is allowed to access when it is located in an allowed area or not in a non-allowed area), etc., and the embodiments of the present application are not limited.

[0204] In another implementation, the terminal device being allowed to access can be replaced by the terminal device being allowed to establish a session service. (R)AN can determine whether the terminal device is allowed to establish a session service based on the third information. The third information can directly indicate the result of whether the terminal device is allowed to establish a session service, for example, the third information indicates that the terminal device is allowed to establish a session service. Alternatively, the third information is reference information for determining whether the terminal device is allowed to establish a session service. Exemplarily, the third information may include S-NSSAI restriction information, and the S-NSSAI restriction information is used to indicate the slice information that the terminal device is allowed to access or the slice information that the terminal device is not allowed to access. (R)AN can determine whether the terminal device is allowed to establish a session service based on the third information and the S-NSSAI carried in the first message. For example, if the S-NSSAI carried in the first message belongs to the slice information that is allowed to access or does not belong to the slice information that is not allowed to access, the (R)AN determines that the terminal device is allowed to establish the session service.

[0205] It can be understood that the (R)AN can determine whether it can (or is able to or needs to) forward the first NAS message to the SMF after receiving the first message, or it can determine whether it can (or is able to or needs to) forward the NAS message to the SMF or determine which types of NAS messages can be forwarded to the SMF before receiving the first message (for example, in the registration process), and after receiving the first message, directly forward the first NAS message to the first SMF (for example, execute step S502) or not forward the first NAS message to the first SMF according to the previously obtained judgment result.

[0206] In a possible implementation, the (R)AN may obtain or receive at least one of the first information, the second information and / or the third information from the registration function network element. For ease of description, the registration function network element is taken as AMF as an example below.

[0207] Before the (R)AN sends the second message to the first SMF, the (R)AN may send an access request message to the AMF registered by the terminal device, wherein the access request message is used to request the terminal device to access the AMF (or request the terminal device to access the network), and the access request message may include the terminal device identifier (the identifier may be a permanent identifier or a temporary identifier of the terminal device); after receiving the access request message, the AMF returns a third message to the (R)AN, the third message is a response message to the access request message or an initial context setup request message (INITIAL CONTEXT SETUP REQUEST MESSAGE), and the third message includes at least one of the first information, the second information or the third information, and the AMF is the AMF registered by the terminal device or the AMF responsible for the access management of the terminal device. It can be understood that the access request message here may be an initial access request message, that is, an access request message initiated by the terminal device for the first time, such as a registration request message or an initial terminal message (INITIAL UE MESSAGE), or may not be an initial access request message (such as an access request message initiated by a terminal device in an idle state), and this application does not limit this.

[0208] Example 1: Taking a session establishment scenario as an example: the first NAS message is used to request the establishment of a first session. For example, the first NAS message is a session establishment request message (eg, PDU Session Establishment Request Message), and the first NAS message includes an identifier of the first session.

[0209] In the registration process of the terminal device (the registration process occurs before the (R)AN receives the first message from the terminal device), the (R)AN can receive at least one of the first information, the second information or the third information from the registration function network element. Specifically, the terminal device sends an AN message to the (R)AN, and the AN message includes an access request message (also called a registration request message); the (R)AN sends an access request message to the AMF, and the AMF receives the access request message; the AMF sends a response message to the access request message (i.e., a third message, such as a registration acceptance message) to the (R)AN, and the (R)AN receives the response message, and the response message includes at least one of the first information, the second information and / or the third information.

[0210] Example 2: Taking the session activation scenario as an example: the first NAS message is used to request activation of the first session. The first NAS message may be a service request message (eg, Service Request Message) or a session activation request message (eg, PDUSession Activation Message). The first NAS message includes an identifier of the first session.

[0211] In the session activation scenario, the terminal device can directly initiate the service request process, or initiate the access process first and then initiate the service request process.

[0212] When the terminal device directly initiates the service request process, after the (R)AN receives the first message from the terminal device, the (R)AN first sends an access request message (also called an access notification message, etc.) to the AMF, and the (R)AN receives a third message from the AMF, which is a response message to the access request message. After the (R)AN determines that the terminal device is connected to the AMF (or network), it continues the activation process of the first session.

[0213] When the terminal device first initiates the access process and then initiates the service request process, before sending the first message, the terminal device will first send a fourth message to the (R)AN, the fourth message includes the second NAS message, and the second NAS message is used to request access to the network or activate the control plane connection; after receiving the fourth message, the (R)AN sends an access request message (also called an access notification message) to the AMF according to the fourth message, and the access request message includes the second NAS message; after receiving the fourth message, the AMF returns a third message to the (R)AN, and the (R)AN receives the third message, which is a response message to the access request message, and the (R)AN forwards the response message to the terminal device. After the terminal device accesses the network or the control plane connection is activated, the terminal device sends the first message to the (R)AN again.

[0214] The AMF registered with the terminal device may send its own identifier (such as AMF ID) to the (R)AN, for example, the third message carries the identifier of the AMF, so that the (R)AN can subsequently provide the identifier of the AMF to the first SMF. Alternatively, the AMF registered with the terminal device may send its own identifier to the terminal context information storage function network element (such as UDR), so that the first SMF can subsequently obtain the identifier of the AMF from the terminal context information storage function network element.

[0215] In an embodiment of the present application, before the (R)AN forwards the first NAS message to the SMF corresponding to the first session (ie, the first SMF), the (R)AN needs to first determine the SMF corresponding to the first session, such as the first SMF.

[0216] Here are some possible implementations:

[0217] Method 1: (R)AN may obtain identification information of the SMF corresponding to the first session from the selection function network element.

[0218] Take the session establishment scenario as an example, see Figure 6 , after the (R)AN receives the first message from the terminal device and before sending the second message to the first SMF, steps S601 to S604 may also be performed.

[0219] S601. (R)AN sends a first request to a selection function network element (eg, NRF), where the first request is used to request selection of an SMF for a first session (or for a terminal device).

[0220] The first request may include the terminal device identifier and network element type information, wherein the network element type information is used to indicate the type of target core network element to be selected, such as SMF. Optionally, the first request may also include a network element selection container, and the network element selection container includes session attribute information such as DNN and S-NSSAI. Accordingly, the first message may also include the network element selection container. Optionally, the first request may also include session attribute information such as DNN and S-NSSAI. Accordingly, the first message also includes session attribute information such as DNN and S-NSSAI.

[0221] The identifier of the terminal device can be a permanent identifier or a temporary identifier, which is not limited in the embodiments of the present application. Among them, the temporary identifier can include an identifier assigned by the (R)AN to the terminal device, or an identifier assigned by the registration function network element (such as AMF) to the terminal device. If the temporary identifier includes an identifier assigned by the registration function network element to the terminal device, the registration function network element can send the identifier assigned to the terminal device to the (R)AN so that the (R)AN can learn the temporary identifier of the terminal device; if the temporary identifier includes an identifier assigned by the (R)AN to the terminal device, the (R)AN can send the identifier assigned to the terminal device to the registration function network element so that the registration function network element can learn the temporary identifier of the terminal device.

[0222] S602: This step is a selectively executable process, and the selected functional network element can obtain the contract data of the terminal device according to the identifier of the terminal device.

[0223] Among them, the subscription data of the terminal device may include network element selection subscription data, access and mobility management subscription data, slice selection subscription data, etc. If the identifier of the terminal device is a temporary identifier, the selection function network element needs to first obtain the permanent identifier corresponding to the temporary identifier, and then obtain the subscription data of the terminal device from the UDM based on the permanent identifier.

[0224] S603. The selection function network element selects the first SMF as the target SMF.

[0225] The selection function network element determines to select the SMF network element according to the network element type information in the first request. Specifically, the network element type information is the SMF network element type.

[0226] For example, the functional network element is selected based on the terminal device subscription data and the first SMF is selected as the target SMF.

[0227] For another example, the selection function network element selects the first SMF as the target SMF according to the network element selection container. Specifically, the selection function network element selects the first SMF responsible for managing the session attributes such as DNN and S-NSSAI according to the session attribute information such as DNN and S-NSSAI included in the network element selection container.

[0228] For another example, the selection function network element selects the first SMF responsible for managing session attributes such as DNN and S-NSSAI according to the session attribute information such as DNN and S-NSSAI included in the first request.

[0229] S604: The selection function network element sends a first response to the (R)AN, the first response including the identification information of the first SMF; accordingly, the (R)AN receives the identification information of the first SMF. Exemplarily, the identification information of the first SMF may be the address information of the first SMF.

[0230] Method 2: (R)AN may obtain the identification information of the SMF corresponding to the first session from a terminal context information storage function network element (such as UDR).

[0231] Taking the session activation scenario as an example, after the first session is created, the first SMF or (R)AN can send the identification information of the first SMF and the identification of the first session to the network storage function network element, and the network storage function network element stores the identification information of the first SMF and the identification of the first session in correspondence. When the terminal device subsequently activates the first session, the (R)AN can obtain or query the SMF corresponding to the first session from the terminal context information storage function network element based on the identification of the first session, for example: the (R)AN sends a second request to the terminal context information storage function network element, the second request is used to query the SMF corresponding to the first session, and the second request includes the identification of the first session; the terminal context information storage function network element determines the identification information of the first SMF based on the identification of the first session, and sends a second response to the (R)AN, and the second response includes the identification information of the first SMF; the (R)AN receives the second response from the terminal context information storage function network element.

[0232] Method 3: The terminal device sends identification information of the first SMF to the (R)AN, and the (R)AN receives the identification information of the first SMF sent by the terminal device.

[0233] Taking the session activation scenario as an example, when creating the first session, the first SMF or (R)AN can send the identification information of the first SMF to the terminal device, and the terminal device stores the identification information of the first SMF. When the terminal device subsequently activates the first session, it can send the identification information of the first SMF, for example, carrying the identification information of the first SMF in the first message.

[0234] Of course, the above-mentioned ways in which the (R)AN obtains the identification information of the first SMF are merely examples and are not limited thereto.

[0235] It can be understood that in the session activation scenario, the terminal device can request to activate one session at a time, or can request to activate multiple sessions. Specifically, the first message can include at least one session identifier and at least one NAS message, the at least one NAS message corresponds to the at least one session, the NAS message corresponding to the first session in the at least one session is used to request to establish or activate the first session, and the first session is any one of the at least one session.

[0236] When the terminal device requests to activate multiple sessions, the terminal device may send the identifier and NAS message corresponding to each session to the (R)AN. For example, if the terminal device requests to activate session A, session B, and session C, the first message may include the identifier of session A and NAS message A (NAS message A is used to request to activate session A), the identifier of session B and NAS message B (NAS message B is used to request to activate session B), and the identifier of session C and NAS message C (NAS message C is used to request to activate session C).

[0237] In some embodiments, in the process of establishing each session, the SMF corresponding to each session can send its own identification information to the terminal device. Accordingly, the terminal device receives and saves the identification information of each SMF from at least one SMF. The terminal device carries the identification information of the corresponding SMF of each session in the at least one session in the first message.

[0238] When the terminal device requests to activate multiple sessions, the method performed by the network on each session is similar to the method performed on the first session, and will not be described in detail here.

[0239] S502. The (R)AN sends a second message to the first SMF, and the first SMF receives the second message; wherein the second message includes the first NAS message and an identifier of the terminal device.

[0240] (R)AN may send a second message to the first SMF according to the identification information of the first SMF. The identification of the terminal device in the second message may be a permanent identification or a temporary identification of the terminal device.

[0241] The second message may also include the identifier of the first session, or may also include the identifier of the AMF. For example, the (R)AN carries the AMF ID obtained from the third message in the second message and sends it to the first SMF.

[0242] It can be understood that when the terminal device requests to activate multiple sessions, the (R)AN can send a second message to the SMF corresponding to each session.

[0243] For example, the second message is an NG application protocol (NGAP) message or a service-based message (such as Nsmf_PDUSession_CreateSMContext Request).

[0244] In combination with the above example, the first message includes the identifier and NAS message A of session A, the identifier and NAS message B of session B, the identifier and NAS message C of session C, session A corresponds to SMF-A, session B corresponds to SMF-B, and session C corresponds to SMF-C, then (R)AN can send a second message to SMF-A, SMF-B, SMF-C, respectively, wherein the second message sent to SMF-A includes NAS message A, the second message sent to SMF-B includes NAS message B, and the second message sent to SMF-C includes NAS message C. It can be understood that when multiple NAS messages correspond to the same SMF, (R)AN can carry the multiple NAS messages in the same message or in different messages, which is not limited in the embodiment of the present application.

[0245] S503: The first SMF accepts or rejects the first NAS message according to the mobility restriction information of the terminal device.

[0246] It can be understood that when the first NAS message is used to request the establishment of the first session, the first SMF accepting the first NAS message means accepting the establishment of the first session. Accordingly, the first SMF will execute the relevant processes for establishing the first session, such as configuring the control plane resources for the first session (such as the first SMF creating the context of the first session), configuring the user plane resources for the first session (such as selecting PCF, establishing session management policy, selecting UPF, establishing N4 session, etc.). For details, please refer to Figure 2 The relevant process of S203 to S217 shown in .

[0247] When the first NAS message is used to request activation of the first session, the first SMF accepting the first NAS message means accepting activation of the first session. Accordingly, the first SMF will execute the relevant processes for activating the first session, such as activating control plane resources for the first session (such as the first SMF updating the context of the first session), configuring user plane resources for the first session (such as selecting a new UPF, establishing a new N4 session, etc.). For details, please refer to Figure 3 The related process of S305~S310 shown in .

[0248] In the embodiment of the present application, the mobility restriction information includes but is not limited to at least one of the following:

[0249] (1) Fourth information: The fourth information is used to indicate whether the terminal device is in the allowed area or the non-allowed area.

[0250] Specifically, when the first SMF determines that the terminal device is not located in the allowed area or in the non-allowed area according to the fourth information, the first SMF rejects the first NAS message. When the first SMF determines that the terminal device is located in the allowed area or not in the non-allowed area according to the fourth information, the first SMF can accept the first NAS message.

[0251] (2) Fifth information: The fifth information is used to indicate the allowed area or the non-allowed area of ​​the terminal device.

[0252] Specifically, the first SMF can determine whether the terminal device is located in the allowed area and / or the non-allowed area based on the location information of the terminal device and the fifth information. When the first SMF determines that the terminal device is not located in the allowed area or is located in the non-allowed area, the first SMF rejects the first NAS message; when the first SMF determines that the terminal device is located in the allowed area or is not located in the non-allowed area, the first SMF can accept the first NAS message. Among them, the first SMF can obtain the location information of the terminal device from the AMF; or the first SMF obtains the location information of the terminal device according to the second message, for example: the second message includes the location information of the terminal device or the second message includes the identifier of the (R)AN, and the first SMF obtains the location information of the terminal device according to the identifier of the (R)AN.

[0253] In some embodiments, the allowed area or the non-allowed area may also be associated with the data network and / or the network slice of the terminal device. For example, the second message also includes an identifier of the data network and / or an identifier of the network slice, or the first NAS message in the second message includes an identifier of the data network and / or an identifier of the network slice, the identifier of the data network is used to indicate the data network used by the terminal device, the identifier of the network slice is used to indicate the network slice used by the terminal device, and the fifth information is used to indicate the allowed area or non-allowed area of ​​the terminal device corresponding to the data network and / or the network slice. When the first SMF determines that the terminal device is not located in the allowed area or in the non-allowed area based on the location information and the fifth information of the terminal device, the first SMF rejects the first NAS message. When the first SMF determines that the terminal device is located in the allowed area of ​​the terminal device corresponding to the data network and / or the network slice included in the second message or the first NAS message based on the location information and the fifth information of the terminal device, or when the first SMF determines that the terminal device is not located in the non-allowed area of ​​the terminal device corresponding to the data network and / or the network slice included in the second message or the first NAS message based on the location information and the fifth information of the terminal device, the first SMF may accept the first NAS message, otherwise reject the first NAS message.

[0254] (3) sixth information, where the sixth information is used to indicate an allowed wireless access technology or an unallowed wireless access technology;

[0255] Specifically, the allowed wireless access technology refers to the wireless access technology that the terminal device is allowed to use when accessing the network, and the non-allowed wireless access technology refers to the wireless access technology that the terminal device is not allowed to use when accessing the network. Since the terminal device accesses the network through the (R)AN, when the wireless access technology of the (R)AN belongs to the allowed wireless access technology, or the wireless access technology of the (R)AN does not belong to the non-allowed wireless access technology, the first SMF can accept the first NAS message, otherwise, reject the first NAS message.

[0256] It can be understood that when the mobility restriction information includes at least two of the above items, each of the at least two items needs to meet the corresponding restriction conditions before the first SMF accepts the first NAS message. If any one of the at least two items does not meet the corresponding restriction conditions, the first SMF rejects the first NAS message.

[0257] For example, when the terminal device is located in the allowed area and the radio access technology of (R)AN belongs to the allowed radio access technology, the first SMF accepts the first NAS message. When the terminal device is located in the allowed area but the radio access technology of (R)AN belongs to the non-allowed radio access technology, or when the radio access technology of (R)AN belongs to the allowed radio access technology but the terminal device is located in the non-allowed area, or the terminal device is located in the non-allowed area and the radio access technology of (R)AN belongs to the non-allowed radio access technology, the first SMF rejects the first NAS message.

[0258] It can be understood that the above mobility restriction information is only an example and is not limited thereto.

[0259] In some embodiments, the first SMF can obtain (such as subscribing or querying) the mobility restriction information of the terminal device from the AMF according to the identifier of the AMF, and the AMF is the AMF registered by the terminal device or the AMF responsible for the access management of the terminal device. If the identifier of the AMF is included in the second message, the first SMF can directly obtain the mobility restriction information of the terminal device from the AMF based on the identifier of the AMF in the second message; or, if the identifier of the AMF is not included in the second message, the first SMF can obtain the identifier of the AMF from the terminal context information storage function network element according to the identifier of the terminal device, and the terminal context information storage function network element stores the correspondence between the identifier of the AMF and the identifier of the terminal device. For example, the identifier of the terminal device in the second message is a temporary identifier, and the first SMF obtains the identifier of the AMF from the terminal context information storage function network element according to the temporary identifier of the terminal device. For another example, the identifier of the terminal device in the second message is a temporary identifier, and the first SMF first obtains the permanent identifier of the terminal device according to the temporary identifier of the terminal device, and then obtains the identifier of the AMF from the terminal context information storage function network element according to the permanent identifier of the terminal device.

[0260] In some other embodiments, the first SMF may obtain (eg, subscribe to or query) the mobility restriction information of the terminal device from a terminal context information storage function network element (eg, UDR) according to the identifier of the terminal device.

[0261] Exemplarily, the context data of the terminal device is stored in the terminal context information storage function network element, and the context data includes mobility restriction information. The first SMF sends a query request to the terminal context information storage function network element, and the query request includes the identifier of the terminal device, and the query request is used to request to obtain the context data of the terminal device; the terminal context information storage function network element returns the context data of the terminal device to the first SMF according to the identifier of the terminal device; the first SMF determines the mobility restriction information of the terminal device from the context data. For example, the identifier of the terminal device in the second message is a temporary identifier, and the query request includes the temporary identifier of the terminal device. For another example, the identifier of the terminal device in the second message is a temporary identifier, and the first SMF first obtains the permanent identifier of the terminal device based on the temporary identifier of the terminal device, and the query request includes the permanent identifier of the terminal device.

[0262] In some embodiments, the first SMF accepting the first NAS message may further include: the first SMF sending a third NAS message to the (R)AN, the third NAS message is used to indicate that the first SMF accepts the first NAS message, and the (R)AN forwards the third NAS message (such as carried in the RRC message) to the terminal device. The third NAS message is, for example, a PDU session create context response (Nsmf_PDUSession_CreateSMContext Response) or a PDU session update context response (Nsmf_PDUSession_UpdateSMContext Response).

[0263] The first SMF rejecting the first NAS message may also include: the first SMF sending a fourth NAS message to the (R)AN, the fourth NAS message is used to indicate that the first SMF rejects the first NAS message, and the (R)AN forwards the fourth NAS message (such as carried in the RRC message) to the terminal device. The fourth NAS message is, for example, a PDU session creation context failure (Nsmf_PDUSession_CreateSMContext Failure) message or a PDU session update context failure (Nsmf_PDUSession_UpdateSMContext Failure) message.

[0264] It should be noted that the above takes the direct connection between (R)AN and SMF through a service-oriented interface as an example, introducing the specific implementation method of direct interaction of NAS messages between (R)AN and SMF. In actual applications, (R)AN and other core network elements (such as UPF, PCF, NRF, etc.) can also be directly connected through a service-oriented interface, thereby realizing direct interaction of NAS messages between (R)AN and other core network elements.

[0265] The embodiment of the present application directly connects the (R)AN with the core network element (such as SMF), so that the (R)AN and the core network element (such as SMF) can directly interact with each other without the need for AMF transit, thereby improving the efficiency of network session-related process management and control.

[0266] In order to better understand the technical solutions of the embodiments of the present application, several complete examples are listed below:

[0267] Example 1, see Figure 7 , is a flow chart of a session establishment method provided in an embodiment of the present application. The method takes AMF performing access registration management and mobility management as an example. The method includes:

[0268] S701, terminal device registration process.

[0269] During the terminal device registration process, the (R)AN can obtain the AMF selected by the network for the terminal device from the selection function network element (such as NRF).

[0270] Among them, the AMF or (R)AN can allocate a temporary identifier (such as UE temp ID) for the terminal device, and the UE tempID is used to identify the terminal device between the (R)AN and the core network element.

[0271] In one possible implementation, the AMF may send mobility restriction information to the terminal device, and the mobility restriction information includes an allowed area and / or a non-allowed area. When the terminal device UE is in an allowed area, it is allowed to initiate PDU session-related services. In another possible implementation, the AMF may notify the (R)AN that the terminal device is in an allowed area or a non-allowed area. Alternatively, the AMF sends a mobility restriction list (Mobility Restriction List) to the (R)AN, and the list includes information on service allowed areas or service non-allowed areas, and the (R)AN determines whether the terminal device is in an allowed area or a non-allowed area based on the list.

[0272] If the terminal is in a non-allowed area, the (R)AN determines not to forward a specific type of NAS message (for example, the (R)AN is pre-configured with which types of NAS messages the (R)AN does not forward or forwards when the terminal is in a non-allowed area). For example, the (R)AN determines not to forward the SM NAS message (nor requests the NRF to discover the SMF). For another example, the (R)AN can forward the Policy NAS message to the PCF network element.

[0273] In one possible implementation, the AMF may determine the type of NAS message that the (R)AN forwards or does not forward. For example, the AMF determines that the (R)AN does not forward the SM NAS message based on that the terminal is in a non-allowed area, and the AMF provides the (R)AN with type information on whether to forward or not forward the NAS message.

[0274] Optionally, the AMF may also send an AMF ID (such as an AMF IP address) to the (R)AN; or, the AMF may send an AMF ID and UE temp ID to the UDR.

[0275] S702, PDU session establishment process, including S702a~S702d:

[0276] S702a, the terminal device sends an AN message to the (R)AN, and the (R)AN receives the AN message from the UE, the AN message including the PDUsession ID (corresponding to the identifier of the first session mentioned above) and the first SM NAS message (corresponding to the first NAS message mentioned above).

[0277] (R)AN can also sense the first SM NAS message type, (R)AN initiates a request to NRF, NRF selects SMF, and NRF sends the identifier of the selected SMF (such as SMF ID) to (R)AN. (R)AN stores the correspondence between PDU session ID and SMF ID (the SMF is responsible for managing the PDU session).

[0278] Among them, the first SM NAS message can be a PDU Session Establishment Request message, which may include PDU session ID, Requested DNN, Requested PDU Session Type, Requested SSC mode, etc.

[0279] S702b. (R)AN sends a request message (corresponding to the second message above) to SMF to request a connection.

[0280] When AMF sends AMF ID (such as AMF IP address) to (R)AN in S701, the request message may include PDU Session ID, UE temp ID, first SM NAS message and AMF ID. Optionally, when AMF changes, (R)AN also notifies SMF of the new AMF ID.

[0281] When AMF sends AMF ID and UE temp ID to UDR in S701, the request message may include PDUSession ID, UE temp ID and the first SM NAS message. Subsequently, SMF may send UE temp ID to UDR, and UDR determines AMF ID based on UE temp ID and sends AMF ID to SMF. Optionally, when AMF changes, UDR also notifies SMF of the new AMF ID.

[0282] After SMF receives the request message, SMF can obtain the terminal's subscription data from UDM according to the UE temp ID, and determine whether to accept the PDU session establishment based on the subscription data and the information in the first SM NAS message.

[0283] S702c, SMF queries or subscribes to AMF whether the terminal is in the AllowedArea based on UE temp ID and AMF ID. If the terminal is in the Non-allowed area, SMF rejects the PDU session establishment. If the terminal is in the Allowed area, SMF accepts the PDU session establishment.

[0284] It can be understood that S702c is an optional step.

[0285] In some embodiments, the DNN that may be included in the first SM NAS message corresponds to a local service, and the SMF may query the AMF whether the terminal is in the LADN. If the terminal is not in the LADN, the SMF rejects the PDU session establishment. If the terminal is in the LADN, the SMF accepts the PDU session establishment.

[0286] In some embodiments, the SMF can also page the terminal device in the idle state according to the AMF ID.

[0287] It is understood that after receiving the first SM NAS message, the SMF can refer to Figure 2 The PDU session establishment process shown, for example, SMF also executes S204, S207a, S207b S208, S209 S210, etc.

[0288] S702d. SMF sends a response message to the (R)AN. The response message may include UE temp ID, N2 SMinfo and the second SM NAS message.

[0289] Among them, N2 SM info may include PDU Session ID, QoS flow identifier QFI, QoS profile QoSProfile, CN Tunnel Info, etc. The second SM NAS message may be a PDU Session EstablishmentAccept message, including QoS Rule, QoS parameters and IP address information, etc. The (R)AN performs the wireless air interface resource configuration of the terminal device according to the N2 SM info, and sends the second SM NAS message to the terminal device. The (R)AN then sends the PDU Session ID, AN Tunnel Info and which QoS flows are accepted to be established to the SMF.

[0290] S703. After receiving the response message, the (R)AN sends an RRC message to the terminal device. The RRC message may include a second SM NAS message.

[0291] For example, the (R)AN sends an RRC message to the terminal device corresponding to the UE temp ID based on the UE temp ID in the response message.

[0292] S704, PDU session modification process.

[0293] In this process, (R)AN (or terminal device) and SMF interact directly, and AMF does not need to participate. For the PDU session modification process initiated by the terminal device, the terminal device sends the PDU Session ID and the third SM NAS message to the (R)AN, and the (R)AN sends the UE temp ID and the third SM NAS message to the corresponding SMF based on the PDU session ID, and the SMF then sends the N2 SM info and the third SM NAS message to the (R)AN. For the PDU session modification process initiated by the SMF, the SMF sends the UE temp ID and N2 SM info to the (R)AN.

[0294] In addition, the network can also perform status management, for example: after the terminal device enters the idle state, the (R)AN actively releases the connection with the AMF / SMF, or the AMF notifies each SMF, and the AMF and SMF actively release the (R)AN connection service.

[0295] In the above scheme, AMF performs access registration management and mobility management, and (R)AN determines whether to send SM NAS message directly to SMF based on AMF configuration information (such as Mobility Restriction List) or forwarding or not forwarding NAS message type information. SMF obtains AMF ID from (R)AN or UDR, queries AMF for terminal device location information (such as whether the terminal device is in the Allowed Area or LADN) and determines whether to accept PDU session establishment. This scheme can improve the flexibility and control efficiency of the PDU session establishment process.

[0296] Example 2, see Figure 8 , is a flowchart of a service request method provided in an embodiment of the present application. The method takes AMF performing access registration management and mobility management as an example. The method includes:

[0297] S801, terminal device registration process, for specific implementation, please refer to S701.

[0298] S802, PDU session establishment process, for specific implementation, please refer to S702.

[0299] S803, uplink service request (SR) process. S803 includes the following two implementation methods:

[0300] Method 1: see S803a to S803c.

[0301] S803a. The terminal device sends an AN message to the (R)AN, and the (R)AN receives the AN message.

[0302] The AN message includes AN parameters and [PDU session ID, SR message]. AN parameters may include 5G-S-TMSI. [PDU session ID, SR message] indicates that each PDU session identifier is associated with an SR message. SR = Service Request. The SR message contains the identifier of the PDU session to be activated (PDU session ID) and the status of the PDU session (PDU Session status). It can be understood that the PDU session ID corresponds to the first NAS message above, and the SR message corresponds to the first NAS message above. It can be understood that the SR message can be replaced by other messages that can activate the PDU session, such as the PDU Session Activation message.

[0303] Optionally, during the PDU session establishment process, the SMF can send the UE temp ID, PDU session ID, and SMF ID to the UDR. After receiving the AN message, the (R)AN can obtain the SMF ID corresponding to [UE temp ID, PDU session ID] from the UDR.

[0304] S803b. (R)AN sends a request message (corresponding to the second message above) to each SMF, where the request message includes SRmessage and UE temp ID.

[0305] The following are some specific implementation methods for S803a~S803b:

[0306] Implementation method 1: RAN sends an access notification / request to AMF (i.e., AMF performs access control). If AMF allows the terminal to access, (R)AN obtains SMF ID from UDR and sends a request message to SMF. SMF obtains AMF ID from UDR based on UE temp ID. In 801, AMF sends AMF ID and UE temp ID to UDR. UE temp ID can be 5G-S-TMSI. Optionally, if UE temp ID is not 5G-S-TMSI, AMF sends UE temp ID to (R)AN after allowing the terminal to access.

[0307] Implementation method 2: (R)AN sends access notification / request to AMF (i.e. AMF performs access control). If AMF allows terminal access, (R)AN obtains SMF ID from UDR and sends a request message to SMF. (R)AN also sends AMF ID to SMF. If UE temp ID is not 5G-S-TMSI, (R)AN receives UE temp ID and AMF ID from AMF; if UE temp ID is 5G-S-TMSI, (R)AN receives AMF ID from AMF.

[0308] Implementation method 3: (R)AN does not send access notification / request to AMF, (R)AN sends a request message to SMF, which also includes AMF ID. If UE temp ID is not 5G-S-TMSI, (R)AN obtains AMF ID and UE temp ID from UDR according to 5G-S-TMSI, and AMF sends 5G-S-TMSI, UE temp ID and AMF ID to UDR in S801 accordingly; if UE tempID is 5G-S-TMSI, (R)AN obtains AMF ID from UDR according to 5G-S-TMSI, and AMF sends 5G-S-TMSI and AMF ID to UDR in S801 accordingly.

[0309] In this implementation, SMF can also ask AMF whether to allow terminal device access based on AMF ID.

[0310] Implementation method 4: (R)AN sends access notification / request to AMF (i.e. AMF performs access control), AMF notifies (R)AN that the terminal is in the allowed / non-allowed area, or AMF sends Mobility RestrictionList to (R)AN, and (R)AN determines whether the terminal is in the allowed / non-allowed area based on the Mobility Restriction List. If the terminal is in the non-allowed area, (R)AN will not send a specific type of NAS message to NF. If the terminal is in the allowed area, (R)AN sends a specific type of NAS message to SMF.

[0311] In this implementation, the AMF may indicate to the (R)AN the specific types of NAS messages that are allowed to be forwarded.

[0312] Implementation method 5: (R)AN sends an access notification / request to AMF (i.e., AMF performs access control). AMF determines whether the terminal device is in Service Area Restriction and stores the result in UDR. SMF obtains from UDR whether the terminal is in allowed / non-allowed area or LADN based on UE temp ID.

[0313] S803c, SMF queries or subscribes to AMF whether the terminal is in the AllowedArea based on UE temp ID and AMF ID. Alternatively, SMF subscribes to mobile events (such as whether it is in the allowed area, inside or outside the LADN) from AMF based on UE temp ID and AMF ID. UE tempID and AMF ID can also be used to page terminal devices in the IDLE state.

[0314] It can be understood that S803c is an optional step.

[0315] The process after SMF receives the (R)AN request can be referred to Figure 2 Related processes in .

[0316] Method 2: see S803d to S803o.

[0317] S803d, the terminal device first sends AN message 1 (corresponding to the fourth message above) to the (R)AN, including AN parameters, and also including an MM NAS message or a registration request message or an access request message (corresponding to the second NAS message above);

[0318] S803e. (R)AN sends the MM NAS message, registration request message or access request message to AMF.

[0319] S803f. (R)AN receives AMF ID / terminal context information (such as Mobility RestrictionList, information on whether the terminal is in an allowed / non-allowed area) from AMF.

[0320] S803g. The terminal device sends AN message 2 (corresponding to the first message above) to (R)AN, including AN parameters and [PDU session ID, SR message]. The SR message can be replaced by a PDU session activation message (PDU Session Activation message). At this time, the terminal device is already in a connected state, and the (R)AN no longer needs to send an access notification / request to the AMF.

[0321] S803o, (R)AN sends a request message (corresponding to the second message above) to SMF, and the request message may include SRmessage and UE temp ID.

[0322] In combination with implementation method 1, the (R)AN can obtain the SMF ID from the UDR and send an SR message to the SMF. The SMF obtains the AMF ID from the UDR based on the UEtemp ID.

[0323] Combined with implementation method 2 or terminal device 3, the (R)AN can obtain the SMF ID from the UDR and send an SRmessage to the SMF, and the (R)AN sends the AMF ID to the SMF.

[0324] In combination with implementation method 4, the (R)AN can determine whether the terminal is in the allowed / non-allowed area based on the Mobility Restriction List or the allowed / non-allowed area indication information sent by the AMF.

[0325] In combination with implementation method 5, AMF can determine whether the terminal device is in Service Area Restriction after receiving the MM NAS message / registration message, and store the result in UDR.

[0326] In the above scheme, the terminal device can send multiple SR messages, each SR message corresponds to a PDU session. After receiving the SR message, the (R)AN obtains the SMF corresponding to the PDU session and sends the SR message to the SMF. After receiving the SR message, the (R)AN sends an access notification / request to the AMF. If the AMF allows the terminal device to access, the AMF can send an SR message to the SMF. The terminal device can first send an access request message to the (R)AN, so that the (R)AN obtains the context information of the terminal from the AMF, and then the terminal device sends an SR message to the (R)AN. At this time, the (R)AN does not need to send an access request message to the AMF. This solution can provide flexibility and control efficiency in the service request process.

[0327] Example 3, see Fig. 9 , is a flowchart of another session management method provided in an embodiment of the present application, wherein the method includes a session establishment process and a service request process. The difference from Examples 1 and 2 is that in Example 3, AMF performs access registration management, while mobility management is independently performed by each core network element.

[0328] S901, terminal device registration process, for specific implementation, please refer to S701.

[0329] S902, PDU session establishment process:

[0330] S902a. The terminal device sends an AN message (corresponding to the first message above) to the (R)AN. The (R)AN receives the AN message, which includes the PDU session ID and the first SM NAS message.

[0331] Optionally, (R)AN senses the SM NAS message type and requests NRF to select SMF, and NRF returns the identifier of the selected SMF (such as SMF ID) to (R)AN. After (R)AN obtains the SMF ID, (R)AN stores the correspondence between PDU session ID and SMF ID (the SMF is responsible for managing the PDU session).

[0332] S902b, (R)AN sends a request message (corresponding to the second message above) to SMF to request a connection. The request message includes PDU Session ID, UE temp ID and the first SM NAS message. The first SM NAS message can be a PDU Session Establishment Request message, including PDU session ID, Requested DNN, Requested PDU Session Type, Requested SSC mode, etc.

[0333] Method 1, (Service Area Restriction does not distinguish between DNN / S-NSSAI): SMF obtains Service Area Restriction (such as Allowed area, RAT restriction) from UDR according to UE temp ID, SMF determines whether the location of the terminal device meets the Service Area Restriction, and accepts or rejects the request. For example, if the (R)AN requesting access is in the Allowed area (SMF is pre-configured with the location information of the (R)AN), the request is accepted. For example, SMF obtains the AMF ID from the (R)AN or UDR, obtains the location information of the terminal device from the AMF, and accepts the request if the terminal device is in the Allowed area. For example, SMF receives a connection request from the (R)AN (corresponding to the terminal accessing through 3GPP RAT). If the RAT restriction indicates that access cannot be made through 3GPP RAT, SMF rejects the request.

[0334] Method 2, (Service Area Restriction distinguishes DNN / S-NSSAI): SMF obtains the Service Area Restriction (such as Allowed area / Non-allowed area) corresponding to each DNN / S-NSSAI from UDR according to UE temp ID, and SMF determines whether the location of the terminal device satisfies the Service Area Restriction corresponding to the Requested DNN / S-NSSAI, and accepts or rejects the request. For example, if the (R)AN accessed by the terminal device is in the Allowed area corresponding to the Requested DNN / S-NSSAI (SMF is pre-configured with the location information of the (R)AN), the request is accepted. For example, SMF obtains the AMF ID from the (R)AN or UDR, obtains the location information of the terminal device from AMF, and if the location of the terminal device is in the Allowed area corresponding to the Requested DNN / S-NSSAI, the request is accepted.

[0335] S902c, PDU session modification process and state management. For specific implementation, please refer to the relevant introduction in Example 1.

[0336] It can be understood that as the terminal device moves, if the (R)AN to which the terminal device accesses is in the Non-allowed area, the SMF will trigger the PDU session release. Specifically, a PDU session release request is sent to the (R)AN, including the UE temp ID, the UE PDU Session ID and the second SM NAS message. The second SM NAS message can be a PDU SessionRelease message.

[0337] When a terminal device needs to transmit a service, the terminal device initiates a service request to activate a PDU session.

[0338] S903, Service Request Process:

[0339] S903a, the terminal device sends an AN message (corresponding to the first message above) to the (R)AN, and the (R)AN receives the AN message. The AN message includes AN parameters and [PDU session ID, SR message]. The AN parameters include 5G-S-TMSI.

[0340] Optionally, the (R)AN obtains the SMF ID corresponding to [UE temp ID, PDU session ID] from the UDR.

[0341] S903b. (R)AN sends a request message (corresponding to the second message above) to each SMF, where the request message includes SRmessage and UE temp ID.

[0342] S903c. SMF determines whether the terminal device is in a Service Area Restriction based on the Service Area Restriction information obtained from the UDR, and accepts or rejects the request.

[0343] The specific implementation of S903c can refer to implementation 1, implementation 2 or implementation 3 in the above example 2, which will not be repeated here.

[0344] In the above scheme, mobility management is independently performed by each core network element (such as SMF). Each core network element obtains the Service Area Restriction from the UDR and determines whether to accept or reject the PDU session establishment or activation request based on the location information of the terminal device and the Service Area Restriction, which can improve the flexibility and control efficiency of the PDU session-related processes.

[0345] The method provided by the embodiment of the present application is introduced above in combination with the accompanying drawings, and the device provided by the embodiment of the present application is introduced below in combination with the accompanying drawings.

[0346] Based on the same technical concept, an embodiment of the present application provides a communication device, which includes a module / unit / means for executing the method executed by any network function or entity in the above method embodiment. The module / unit / means can be implemented by software, or by hardware, or the corresponding software can be implemented by hardware.

[0347] For example, see Fig.10 , the device 100 may include a transceiver unit 1001 and a processing unit 1002 .

[0348] As an example, when the device 100 is the access network element or is located in the access network element, the transceiver unit 1001 is used to receive a first message from a terminal device, the first message includes an identifier of a first session and a first non-access layer NAS message, and the first NAS message is used to request to establish or activate a first session corresponding to the identifier; send a second message to a first session management function network element, the second message includes the first NAS message and the identifier of the terminal device. Optionally, the processing unit 1002 is used to determine the second message according to the first message.

[0349] As another example, when the device 100 is the above-mentioned first session management function network element or is located in the above-mentioned first session function network element, the transceiver unit 1001 is used to receive a second message from the access network network element, the second message includes a first NAS message and an identifier of the terminal device, and the first NAS message is used to request to establish or activate a first session; the processing unit 1002 is used to accept or reject the first NAS message according to the mobility restriction information of the terminal device.

[0350] As another example, when the device 100 is the above-mentioned registration function network element or is located in the above-mentioned registration function network element, the transceiver unit 1001 is used to receive an access request message from an access network network element, the access request message is used to request that the terminal device be connected to the registration function network element (or network) where the device is located; send a third message to the access network network element, the third message includes at least one information, and the at least one information is used by the access network network element to determine whether to forward the first NAS message. Optionally, the processing unit 1002 is used to determine the third message according to the access request message.

[0351] As another example, when the apparatus 100 is the above-mentioned terminal device or is located in the above-mentioned terminal device, the processing unit 1002 is used to generate a first message; the transceiver unit 1001 is used to send the first message to the access network element; wherein the first message includes at least one session identifier and at least one NAS message, at least one NAS message corresponds to at least one session, and the NAS message corresponding to each session in the at least one session is used to request to establish or activate each session.

[0352] It should be understood that all relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module and will not be repeated here.

[0353] In specific implementation, the above device can have a variety of product forms. Several possible product forms are introduced below.

[0354] See also Fig.11 , the embodiment of the present application also provides a communication device 110. It is understandable that the communication device 110 includes necessary forms of technical means such as modules, units, elements, circuits, or interfaces, which are appropriately configured together to implement the present solution. The communication device 110 can be any network function or entity in the above method embodiment, or a component (such as a chip) in these functions and entities, to implement the method performed by any network function or entity in the above method embodiment.

[0355] The communication device 110 includes one or more processors 111. The processor 111 may be a general-purpose processor or a dedicated processor, etc. For example, it may be a baseband processor or a central processing unit. The baseband processor may be used to process the communication protocol and communication data, and the central processing unit may be used to control the communication device (such as a RAN node, a terminal, or a chip, etc.), execute a software program, and process the data of the software program.

[0356] In one possible design, the processor 111 may include a program 113 (sometimes also referred to as code or instructions), which can be run on the processor 111 so that the communication device 110 executes the method performed by any network function or entity in the above method embodiments.

[0357] In another possible design, the communication device 110 includes a circuit ( Fig.11 The circuit is used to implement the functions of the method executed by any network function or entity in the above method embodiments.

[0358] In a specific implementation, the communication device 110 may include one or more memories 112, on which a program 114 (sometimes also referred to as code or instruction) is stored. The program 114 can be run on the processor 111, so that the communication device 110 executes the method executed by any network function or entity in the above method embodiments.

[0359] In some embodiments, the processor 111 and / or the memory 112 may include an AI module 117, 118, and the AI ​​module is used to implement AI-related functions. The AI ​​module may be implemented by software, hardware, or a combination of software and hardware. For example, the AI ​​module may include a RIC module. For example, the AI ​​module may be a near real-time RIC or a non-real-time RIC.

[0360] In a specific implementation, data may also be stored in the processor 111 and / or the memory 112. The processor and the memory may be provided separately or integrated together.

[0361] The communication device 110 may also include a transceiver 115 and / or an antenna 116. The processor 111 may also be sometimes referred to as a processing unit, which controls the communication device (e.g., a RAN node or a terminal). The transceiver 115 may also be sometimes referred to as a transceiver unit, a transceiver, a transceiver circuit, or a transceiver, etc., which is used to implement the transceiver function of the communication device through the antenna 116.

[0362] It should be understood that the processor mentioned in the embodiments of the present application can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc. When implemented by software, the processor can be a general-purpose processor implemented by reading software code stored in a memory.

[0363] Exemplarily, the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0364] It should be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM) and direct memory bus random access memory (DirectRambus RAM, DR RAM).

[0365] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) can be integrated into the processor.

[0366] It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0367] Based on the same technical concept, an embodiment of the present application also provides a computer-readable storage medium, including a program or instruction. When the program or instruction runs on a computer, the method performed by any network function or entity in the above method embodiment is executed.

[0368] Based on the same technical concept, an embodiment of the present application also provides a computer program product comprising instructions, wherein the computer program product stores instructions, and when the computer program product is run on a computer, the method performed by any network function or entity in the above method embodiments is executed.

[0369] Based on the same technical concept, the embodiment of the present application also provides a chip, which may include a processor and a memory (or the chip is coupled to the memory), and the processor executes program instructions in the memory to execute the method executed by any network function or entity in the above method embodiment. Wherein, "coupling" refers to the direct or indirect combination of two components, such as coupling can refer to the electrical connection between two components.

[0370] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0371] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1A device that provides the functions specified in a block or multiple blocks.

[0372] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0373] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0374] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A session management method, characterized in that: include: The access network element receives a first message from the terminal device, where the first message includes an identifier of the first session and a first non-access layer NAS message, where the first NAS message is used to request to establish or activate a first session corresponding to the identifier; The access network element sends a second message to the first session management function element, where the second message includes the first NAS message and an identifier of the terminal device.

2. The method according to claim 1, characterized in that Before the access network element sends the second message to the first session management function network element, the method further includes: The access network element receives a third message from a registration function network element, where the third message includes at least one information, and the registration function network element is a registration function network element where the terminal device is registered; The access network element sends a second message to the first session management function network element, including: The access network element sends the second message to the first session management function element according to the at least one information.

3. The method according to claim 2, characterized in that The at least one information includes first information, the first information is used to indicate that the terminal device is located in an allowed area or is not located in a non-allowed area, or the first information is used to indicate an allowed area and / or a non-allowed area; The access network element sending the second message to the first session management function network element according to the at least one information includes: If the terminal device is located in the allowed area or is not located in the non-allowed area, the access network element sends the second message to the first session management function network element.

4. The method according to claim 2, characterized in that The at least one information includes second information; The second information is used to indicate an allowed message type, and the access network element sends the second message to the first session management function network element according to the at least one information, including: if the allowed message type includes a message type corresponding to the first NAS message, the access network element sends the second message to the first session management function network element; or The second information is used to indicate a non-allowed message type, and the access network network element sends the second message to the first session management function network element according to the at least one information, including: if the non-allowed message type does not include the message type corresponding to the first NAS message, then the access network network element sends the second message to the first session management function network element.

5. The method according to any one of claims 2 to 4, characterized in that: The at least one information includes third information, and the third information is used to indicate whether the terminal device is allowed to access; The access network element sending the second message to the first session management function network element according to the at least one information includes: If the third information is used to indicate that the terminal device is allowed to access, the access network element sends the second message to the first session management function network element.

6. The method according to any one of claims 2 to 5, characterized in that: The third message also includes the identifier of the registration function network element, and the second message also includes the identifier of the registration function network element.

7. The method according to any one of claims 1 to 6, characterized in that: The first NAS message is used to request establishment of a first session corresponding to the identifier, the first NAS message is a session establishment request message, and the first NAS message includes the identifier of the first session; After the access network element receives the first message from the terminal device and before the access network element sends the second message to the first session management function network element, the method further includes: The access network element sends a first request to the selection function network element, where the first request is used to request selection of a session management function network element for the first session; The access network element receives a first response from the selection function network element, where the first response includes identification information of the first session management function network element; The access network element sends a second message to the first session management function network element, including: The access network element sends the second message to the first session management function element according to the identification information of the first session management function element.

8. The method according to any one of claims 2 to 6, characterized in that: The first NAS message is used to request establishment of a first session corresponding to the identifier, the first NAS message is a session establishment request message, and the first NAS message includes the identifier of the first session; Before the access network element receives the first message from the terminal device, the method further includes: The access network element sends an access request message to the registration function element, and the third message is a response message to the access request message.

9. The method according to any one of claims 1 to 6, characterized in that: The first NAS message is used to request activation of the first session corresponding to the identifier, and the first NAS message is a service request message or a session activation request message; The first NAS message includes an identifier of the first session; The access network element sends a second message to the first session management function network element, including: The access network element obtains identification information of the first session management function network element; The access network element sends the second message to the first session management function element according to the identification information of the first session management function element.

10. The method according to claim 9, characterized in that The access network element obtains the identification information of the first session management function network element, including: The access network element sends a second request to the terminal context information storage function network element, where the second request is used to query the session management function network element corresponding to the first session; The access network element receives a second response from the terminal context information storage function element, where the second response includes identification information of the first session management function element.

11. The method according to claim 9, characterized in that The first message includes identification information of the first session management function network element; The access network element obtains the identification information of the first session management function network element, including: The access network element obtains identification information of the first session management function network element from the first message.

12. The method according to any one of claims 2 to 6, characterized in that: The first NAS message is used to request activation of the first session corresponding to the identifier, and the first NAS message is a service request message or a session activation request message; The first NAS message includes an identifier of the first session; The method further comprises: Before the access network element receives the third message from the registration function element, the access network element sends an access request message to the registration function element, where the access request message includes an identifier of the terminal device, and the third message is a response message to the access request message.

13. The method according to claim 12, characterized in that The access network element sends an access request message to the registration function network element, including: After the access network element receives the first message from the terminal device, the access network element sends the access request message to the registration function network element.

14. The method according to claim 12, characterized in that Before the access network element receives the first message from the terminal device, the method further includes: the access network element receives a fourth message from the terminal device, the fourth message includes a second NAS message, and the second NAS message is used to request access to the network or activate a control plane connection; The access network element sends an access request message to the registration function network element, including: the access network element sends the access request message to the registration function network element according to the fourth message, and the access request message includes the second NAS message.

15. The method according to any one of claims 9 to 14, characterized in that: The first message includes an identifier of at least one session and at least one NAS message, the at least one NAS message corresponds to the at least one session in one-to-one correspondence, the NAS message corresponding to a first session in the at least one session is used to request establishment or activation of the first session, and the first session is any one of the at least one session; The access network element sends a second message to the first session management function network element, including: The access network element sends a second message to the session management function network element corresponding to each session.

16. A session management method, characterized in that: The method comprises: The terminal device generates a first message; The terminal device sends the first message to the access network element; The first message includes an identifier of at least one session and at least one NAS message, the at least one NAS message corresponds to the at least one session one-to-one, and the NAS message corresponding to each session in the at least one session is used to request establishment or activation of each session.

17. The method according to claim 16, characterized in that The first message also includes identification information of at least one session management function network element, the identification information of the at least one session management function network element corresponds one-to-one to the at least one session, and each session management function network element in the at least one session management function network element is responsible for managing the session corresponding to the identification information of each session management function network element.

18. The method according to claim 17, characterized in that The method further comprises: The terminal device receives identification information of each session management function network element from each session management function network element of the at least one session management function network element.

19. The method according to any one of claims 16 to 18, characterized in that: Before the terminal device sends the first message, the method further includes: The terminal device sends a fourth message to the access network element, where the fourth message includes a second NAS message, and the second NAS message is used to request access to the network or activate a control plane connection.

20. A communication device, characterized in that: The method comprises a module or a unit for executing the method according to any one of claims 1 to 15, or comprises a module or a unit for executing the method according to any one of claims 16 to 19.

21. A communication device, characterized in that: include: A processor, the processor is coupled to a memory, the memory is used to store programs or instructions, when the program or instructions are executed by the processor, the communication device executes the method as described in any one of claims 1-15, or the communication device executes the method as described in any one of claims 16-19.

22. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or instruction. When the computer program or instruction is executed by the communication device, the method according to any one of claims 1 to 15 is implemented, or the method according to any one of claims 16 to 19 is implemented.

23. A chip, characterized in that: The chip includes a processor, and the processor is used to execute program instructions in the storage to perform the method as claimed in any one of claims 1-15, or to perform the method as claimed in any one of claims 16-19.

24. A communication system, characterized in that: Including communication devices and terminal equipment; The communication device is used to execute the method according to any one of claims 1 to 15, and the terminal equipment is used to execute the method according to any one of claims 16 to 19.

25. A computer program product comprising instructions, characterized in that The computer program product stores instructions, and when the instructions are executed on a computer, the computer is caused to execute the method according to any one of claims 1 to 15, or the computer is caused to execute the method according to any one of claims 16 to 19.

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