Communication method, system and apparatus

Abstract

A communication method, system and apparatus. In the technical solution provided by the present application: on the basis of first handover time information, a first access network device sends a handover request message of a terminal to a second access network device, wherein the first handover time information comprises a corresponding duration during which at least one access network device serves the terminal; when receiving the handover request message, the second access network device communicates with a user plane function network element on the basis of the handover request message and core network tunnel information of the terminal stored in the second access network device. Therefore, signaling interaction, which is related to the core network tunnel information, between the second access network device and a core network device is reduced, and the handover efficiency of a terminal handover process is improved.

Description

Communication method, system and device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on September 20, 2023, with application number 202311225980.0 and application name “A Communication Method, System and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of wireless communication technology, and in particular to a communication method, system, and device. Background Art

[0003] In the scenario where the satellite communication mode is the regenerative transmission mode, the base station or part of the base station functions are deployed on the satellite, and the satellites can complete the signaling interaction and user data transmission between base stations.

[0004] Generally, even if user equipment (UE) is stationary, changes in the coverage (or signal strength, etc.) of the wireless signal provided by the radio access network (RAN) deployed on the satellite as it flies will trigger a handover process for the UE, meaning the UE switches from accessing a source access network device to accessing a target access network device. However, the core network serves a large number of UEs, and low-orbit satellites move rapidly. Each UE frequently switches to a different target access network device, resulting in frequent transmission of UE information between access network devices and core network equipment. Improving handover efficiency is a pressing issue in this scenario.

[0005] Summary of the Invention

[0006] The present application provides a communication method, system and device to improve the switching efficiency problem of terminals frequently triggering switching processes.

[0007] In a first aspect, the present application provides a communication method, which is applied to a second access network device, and the method includes: receiving a switching request message from a first access network device, wherein the switching request message is used to request that a terminal be switched to the second access network device; and communicating with a user plane functional network element based on the switching request message and the core network tunnel information of the terminal stored in the second access network device.

[0008] In an embodiment of the present application, after the second access network device receives the switching request message from the terminal, it communicates with the UPF based on the core network tunnel information of the terminal stored in the second access network device, thereby reducing the signaling interaction between the second access network device and the core network device regarding the core network tunnel information. For example, the process of the second access network device requesting and waiting for the UPF to allocate core network tunnel information to the terminal in the switching process is omitted, thereby improving the switching efficiency of the terminal that frequently executes the switching process.

[0009] In a possible implementation, before receiving the handover request message from the first access network device, the method further includes: receiving core network tunnel information of the terminal, and storing the core network tunnel information.

[0010] In one possible implementation, the receiving of the core network tunnel information of the terminal includes: receiving the core network tunnel information of the terminal from the first access network device, the core network tunnel information of the terminal being the core network tunnel information that the first access network device requests the user plane functional network element to allocate to the terminal, the core network tunnel information being used to establish a tunnel between the second access network device and the user plane functional network element, the tunnel being used to carry data of the terminal. Alternatively, the receiving of the core network tunnel information of the terminal includes: receiving the core network tunnel information of the terminal from the session management functional network element, the core network tunnel information of the terminal being the core network tunnel information that the user plane functional network element allocated for establishing a tunnel between the second access network device and the user plane functional network element when the terminal previously accessed the second access network device.

[0011] In one possible implementation, after receiving the switching request message from the first access network device, the method further includes: if the second access network device does not store the core network tunnel information of the terminal, or the second access network device does not allocate access network tunnel information to the terminal, then sending a path switching message to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

[0012] Exemplarily, the path corresponding to the switching terminal may be to switch the tunnel of the GPRS user plane part (user plane part of GTP, GTP-U) of the terminal session from the first access network device to the user plane function network element (UPF) to the tunnel from the second access network device to the UPF, where the UPF corresponding to the first access network device and the UPF corresponding to the second access network device may be the same or different, and this document does not limit this.

[0013] Specifically, the path switching message can be used to trigger the access and mobility management function network element (AMF) to request the UPF to allocate core network tunnel information to the terminal through the session management network element (SMF). The core network tunnel information is used to establish a tunnel between the second access network device and the user plane function network element for carrying data of the terminal. In some other possible implementations, the path switching message carries the terminal identifier assigned by the second access network device to the terminal. The path switching message is also used to trigger the AMF to update the second identifier of the terminal. The second identifier is a private terminal identifier allocated to the terminal by the access network device to which the terminal is currently connected and stored in the AMF. It is used to identify the terminal between the AMF and the access network device.

[0014] In one possible implementation, after receiving the switching request message from the first access network device, the method further includes: if the second access network device has stored the core network tunnel information of the terminal and the second access network device has allocated access network tunnel information to the terminal, then no path switching message is sent to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

[0015] In a possible implementation manner, the method further includes: allocating the access network tunnel information to the terminal; and sending the access network tunnel information to an access and mobility management function network element.

[0016] In an embodiment of the present application, the second access network device may send access network tunnel information allocated by the second access network device to the terminal to the AMF when the second access network device is in a connected state or an idle state with the terminal. The second access network device and the terminal are in a connected state when the terminal is connected to the second access network device, and the second access network device and the terminal are in an idle state when the terminal is not connected to the terminal.

[0017] In one possible implementation, before receiving the switching request message from the first access network device, the method further includes: receiving a first request, the first request being used to request allocation of access network tunnel information for the terminal; allocating access network tunnel information to the terminal based on the first request; and sending a first response, the first response carrying the access network tunnel information.

[0018] In a possible implementation, the first response further carries an identifier of the second access network device.

[0019] In a possible implementation manner, the first request includes identification information of the first session of the terminal, and the first request is specifically used to request allocation of access network tunnel information for the first session.

[0020] In one possible implementation, the first request comes from the first access network device, and sending the first response includes: sending the first response to the first access network device, the first response carrying the access network tunnel information and first indication information, and the first indication information is used to instruct the first access network device to send the access network tunnel information to the access and mobility management function network element.

[0021] In a possible implementation manner, the first request comes from the access and mobility management function network element, and the sending the first response includes: sending the first response to the access and mobility management function network element.

[0022] In a possible implementation manner, the core network tunnel information corresponds to the first session of the terminal.

[0023] In one possible implementation, before receiving the switching request message from the first access network device, the method further includes: receiving a second request from the first access network device, the second request being used to request the second access network device to assign a terminal identifier to the terminal; based on the second request, assigning a terminal identifier to the terminal; and sending a second response to the first access network device, the second response carrying the terminal identifier.

[0024] In a possible implementation, the second response further carries second indication information, where the second indication information is used to instruct the first access network device to send the terminal identifier to the access and mobility management function network element.

[0025] In one possible implementation, the terminal is a stationary terminal. Exemplarily, whether the UE is stationary or mobile can be determined based on the expected UE behavior in the terminal's subscription information. Alternatively, whether the UE is a stationary terminal can be determined based on the UE's location information over a period of time. In one possible implementation, after receiving the handover request message, the second access network device determines whether the terminal is a stationary terminal, and if it is determined that the terminal is a stationary terminal, communicates with the UPF based on the core network tunnel information stored in the second access network device.

[0026] In one possible implementation, after receiving the switching request message from the first access network device, the method further includes: receiving first access network tunnel information from a session management network element, where the first access network tunnel information is allocated by the session management network element for establishing a tunnel for the terminal between the second access network device and the UPF.

[0027] In a second aspect, the present application provides a communication method, which is applied to a first access network device, and the method includes: determining to switch the terminal to a second access network device based on first switching time information of the terminal, the first switching time information including the time when at least one access network device serves the terminal, and the at least one access network device includes the second access network device; sending a switching request message to the second access network device, the switching request message being used to request that the terminal be switched to the second access network device.

[0028] In an embodiment of the present application, the first switching time information stored in the first access network device and the second switching time information stored in the AMF both include the time when the access network device serves the terminal, and the first switching time information and the second switching time information correspond to each other within a certain error range.

[0029] Using the communication method provided in the present application, the first access network device initiates a switching request to the second access network device based on the first switching time information, and the AMF switches the terminal to the second access network device based on the second switching time information. That is, the air interface switching of the terminal between the first access network device and the second access network device and the update of the tunnel information of the terminal on the core network side are synchronized based on the switching time information. The first access network device or the second access network device does not need to send a synchronization message (such as a path switching message) to the AMF about switching the terminal to the second access network device, thereby reducing the signaling interaction between the access network device and the core network device about the terminal information, while ensuring the consistency and integrity of the terminal switching process, and improving the switching efficiency.

[0030] In one possible implementation, the method further includes: determining the first switching time information based on the access time of the terminal to the at least one access network device during the satellite operation cycle; or, determining the first switching time information based on the position and ephemeris information of the terminal; or, receiving the first switching time information from the access and mobility management function network element.

[0031] In one possible implementation, the satellite corresponding to the at least one access network device and the satellite corresponding to the first access network device belong to the same constellation; or, the satellite corresponding to the at least one access network device and the satellite corresponding to the first access network device have a direct and / or indirect inter-satellite link connection; or, the coverage range of each of the at least one access network device includes the location of the terminal.

[0032] The coverage range of each of the at least one access network devices may refer to the entire range covered by the signal of each access network device when the access network device moves along the operating trajectory. Accordingly, the coverage range of each of the at least one access network devices including the location of the terminal may refer to the entire range covered by the signal of each access network device including the location of the terminal.

[0033] In one possible implementation, before sending a switching request message to the second access network device, the method further includes: requesting the second access network device to allocate access network tunnel information for the terminal; receiving the access network tunnel information from the second access network device; and sending the access network tunnel information to the access and mobility management function network element.

[0034] In an embodiment of the present application, the first access network device can forward the access network tunnel information allocated to the terminal by other access network devices (the other access network devices include the second access network device) to the AMF. For example, the other access network devices can be all access network devices or part of the access network devices that can serve the terminal except the first access network device, which is equivalent to the signaling interaction of sending the access network tunnel information of all access network devices (or the part of the access network devices) to the AMF, and merging them into the same message and sending them. When the terminal accesses the corresponding access network device for the first time or subsequently, it can send the path switching message carrying the access network tunnel information to the AMF without going through the NG interface, thereby alleviating the communication pressure of the NG interface and further improving the switching efficiency.

[0035] In a possible implementation, requesting the second access network device to allocate access network tunnel information for the terminal includes: requesting the second access network device to allocate access network tunnel information for the first session of the terminal.

[0036] In one possible implementation, the requesting the second access network device to allocate access network tunnel information for the first session of the terminal includes: during the process of the terminal establishing the first session through the first access network device, requesting the second access network device to allocate access network tunnel information for the first session.

[0037] In one possible implementation, before sending a switching request message to the second access network device, the method further includes: requesting other access network devices to allocate a terminal identifier for the terminal, the other access network devices including one or more access network devices other than the first access network device among the at least one access network device; receiving the terminal identifier allocated to the terminal by the other access network devices; and sending the terminal identifier allocated to the terminal by the other access network devices to the access and mobility management function network element.

[0038] In one possible implementation, requesting the at least one access network device to allocate a terminal identifier for the terminal includes: during the process of establishing a first session by the terminal through the first access network device, requesting the at least one access network device to allocate a terminal identifier for the terminal.

[0039] In an embodiment of the present application, the first access network device can forward the terminal identifier assigned to the terminal by other access network devices (the other access network devices include the second access network device) to the AMF. For example, the other access network devices are all access network devices or part of the access network devices that can serve the terminal except the first access network device. This is equivalent to sending the signaling interaction of the terminal identifier of all access network devices (or the part of the access network devices) to the AMF, and merging them into the same message and sending them. When the terminal accesses the corresponding access network device for the first time or subsequently, it does not need to send a path switching message carrying the terminal identifier to the AMF through the NG interface, thereby further alleviating the communication pressure of the NG interface and improving the switching efficiency.

[0040] In one possible implementation, before sending a switching request message to the second access network device, the method also includes: requesting the user plane functional network element to allocate core network tunnel information for the terminal; receiving first core network tunnel information from the user plane functional network element, the first core network tunnel information corresponding to the access network device; and sending the first core network tunnel information to the second access network device.

[0041] For example, when a terminal establishes a session through a first access network device, the first access network device requests the user plane functional network element to allocate core network tunnel information for the session. The request may carry information about other access network devices. The other access network devices may include all or part of the access network devices whose coverage includes the location of the terminal, other than the first access network device, such as a second access network device and a third access network device. Based on the request, the user plane functional network element may allocate core network tunnel information for the session. The core network tunnel information corresponds to the other access network devices, such as second core network tunnel information corresponding to the second access network device and third core network tunnel information corresponding to the third access network device. Furthermore, the user plane functional network element may send the allocated core network tunnel information to the corresponding access network device via the first access network device, or may send it to the corresponding access network device via the AMF, i.e., sending the second core network tunnel information to the second access network device and sending the third core network tunnel information to the third access network device.

[0042] In a possible implementation manner, the terminal is a stationary terminal.

[0043] In one possible implementation, before determining to switch the terminal to the second access network device based on the first switching time information of the terminal, the method further includes: the first access network device determines whether the terminal is a stationary terminal, and determines to switch the terminal to the second access network device based on the first switching time information of the terminal.

[0044] In a possible implementation manner, the first access network device obtains (or determines) the first switching time information when determining that the terminal is a stationary terminal.

[0045] In a third aspect, the present application provides a communication method, which is applied to an access and mobility management function network element, and the method includes: based on the second switching time information of the terminal, determining to switch the terminal from a first access network device to a second access network device, the second switching time information including the time when at least one access network device serves the terminal, and the at least one access network device includes the second access network device; sending a first message to the session management function network element, the first message being used to update the access network tunnel information of the terminal.

[0046] In an embodiment of the present application, the AMF actively triggers the execution of the corresponding process for the UE to switch to the second access network device based on the second switching time information, which may specifically include sending the above-mentioned first message to the session management function network element (SMF), without relying on the path switching message sent by the second access network device, thereby improving the switching efficiency and alleviating the communication pressure of the NG interface.

[0047] In a possible implementation, the first message includes one or more of the following: access network tunnel information allocated by the second access network device to the terminal; an identifier of the second access network device; and an identifier of the first session of the terminal.

[0048] In a possible implementation manner, when the first message includes the identifier of the first session, the first message is specifically used to update the access network tunnel information of the first session.

[0049] For example, if the access network tunnel information corresponds to only one session, and the session is the first session, assuming that the SMF stores access network tunnel information corresponding to the identifier of the access network device and the identifier of the session, then the first message may include the identifier of the first session and the identifier of the second access network device. Accordingly, after receiving the first message, the SMF may update the access network tunnel information of the first session based on the identifier of the first session and the identifier of the second access network device.

[0050] For example, if the access network tunnel information corresponds to only one session, and the session is the first session, assuming that the second access network device allocates the first access network tunnel information to the first session, then the first message may include the identifier of the first session and the first access network tunnel information. Accordingly, after receiving the first message, the SMF may update the access network tunnel information of the first session based on the identifier of the first session and the access network tunnel information.

[0051] In one possible implementation, the method further includes: the access and mobility management function network element determines the second switching time information based on the access time of the terminal accessing the at least one access network device respectively during the satellite operation cycle; or, the access and mobility management function network element determines the second switching time information based on the position and ephemeris information of the terminal.

[0052] In a possible implementation, the method further includes: receiving access network tunnel information allocated by the second access network device to the terminal; and sending the access network tunnel information allocated by the second access network device to the terminal to the session management function network element.

[0053] In an embodiment of the present application, the access network tunnel information allocated by the second access network device to the terminal can be sent to the AMF through the first access network device. For example, when the terminal accesses the first access network device, the first access network device requests other access network devices (including the second access network device) to allocate access network tunnel information to the terminal. After the first access network device receives the access network tunnel information allocated by the other access network devices to the terminal, it sends it to the AMF. Alternatively, the access network tunnel information allocated by the second access network device to the terminal can also be sent directly to the AMF by the second access network device. For example, after the second access network device receives the above-mentioned switching request message, the second access network device sends the access network tunnel information to the AMF, or when the terminal previously accesses the second access network device, the second access network device sends it to the AMF, and the AMF receives and stores the access network tunnel information. When the AMF determines to switch the terminal to the second access network device, it sends the above-mentioned first message to the SMF based on the access network tunnel information.

[0054] In a possible implementation manner, the access network tunnel information includes aggregated access network tunnel information.

[0055] In one possible implementation, before determining to switch the terminal to the second access network device based on the second switching time information of the terminal, the method further includes: receiving a terminal identifier assigned to the terminal by other access network devices from the first access network device, the other access network devices including one or more access network devices other than the first access network device among the at least one access network device; after determining to switch the terminal to the second access network device, the method further includes: updating the terminal identifier of the terminal recorded in the access and mobility management function network element to the terminal identifier assigned to the terminal by the second access network device based on the terminal identifier assigned to the terminal by the other access network devices.

[0056] In a possible implementation manner, the coverage of the at least one access network device includes the location of the terminal.

[0057] Specifically, the entire range of signal coverage of each of the at least one access network device during operation includes the location of the terminal. It should be noted that the entire range of signal coverage of the access network device during operation includes the location of the terminal means that when the access network device operates to a certain position (for example, the upper left, upper right, or directly above the terminal), the signal coverage of the access network device includes the location of the terminal, and does not mean that the communication coverage of the access network device includes the location of the terminal at every moment during the entire operation process of the access network device.

[0058] In a possible implementation manner, the terminal is a stationary terminal.

[0059] In some possible implementations, determining to switch the terminal to the second access network device based on the first switching time information of the terminal specifically includes: when the terminal is a stationary terminal, determining to switch the terminal to the second access network device based on the first switching time information of the terminal.

[0060] In a fourth aspect, the present application provides a communication method applied to a session management function network element, the method comprising: receiving a first message from an access and mobility management function network element, the first message being used to update the access network tunnel information of a terminal, the first message including an identifier of a second access network device; allocating access network tunnel information to the terminal based on the identifier of the second access network device; and sending the allocated access network tunnel information to a user plane function network element, the allocated access network tunnel information being used by the user plane function network element to update the access network tunnel information of the terminal.

[0061] In the embodiment of the present application, the allocated access network tunnel information is the access network tunnel information allocated to the terminal based on the identifier of the second access network device.

[0062] By adopting the communication method provided in this application, SMF allocates access network tunnel information to the terminal, so that there is no need for signaling interaction about access network tunnel information between the access network device and AMF, further reducing the signaling interaction time in the switching process and improving switching efficiency.

[0063] In a possible implementation manner, the method further includes: sending core network tunnel information of the terminal to the second access network device.

[0064] In a possible implementation manner, the method further includes: sending the allocated access network tunnel information to the second access network device.

[0065] In a fifth aspect, the present application provides a communication method, applied to a session management function network element, the method comprising: receiving access network tunnel information allocated to a terminal by a second access network device from an access and mobility management function network element; receiving a first message from the access and mobility management function network element, the first message being used to update the access network tunnel information of the terminal, the first message including an identifier of the second access network device; based on the identifier of the second access network device, sending the access network tunnel information allocated to the terminal by the second access network device to a user plane function network element, the access network tunnel information being used by the user plane function network element to update the access network tunnel information of the terminal.

[0066] Specifically, before the terminal accesses the second access network device, the SMF receives the access network tunnel information allocated to the terminal by the second access network device sent by the AMF. When the terminal accesses the second access network device, the SMF receives a first message from the AMF. Based on the identifier of the second access network device carried in the first message, the SMF determines the access network tunnel information of the second access network device serving the terminal, and sends the access network tunnel information to the user plane functional network element.

[0067] By adopting the communication method provided in the present application, when the terminal accesses the second access network device, the access network tunnel information of the second access network device serving the terminal is already stored in the SMF, so that the AMF does not need to send the access network tunnel information of the second access network device serving the terminal to the SMF through the first message, and the second access network device does not need to send the access network tunnel information of the second access network device serving the terminal to the AMF, thereby reducing the signaling interaction during the switching process, alleviating the communication pressure, and further improving the switching efficiency.

[0068] In a possible implementation manner, before receiving the first message from the access and mobility management function network element, the method further includes: sending the core network tunnel information of the terminal to the second access network device.

[0069] In a sixth aspect, the present application provides a communication system, comprising a first access network device, a second access network device, and an access and mobility management function network element; wherein, the second access network device is used to execute the method shown in the first aspect or any possible implementation of the first aspect; the first access network device is used to execute the method shown in the second aspect or any possible implementation of the second aspect; the access and mobility management function network element is used to execute the method shown in the third aspect or any possible implementation of the third aspect.

[0070] In one possible implementation, the system further includes a session management function network element; the session management function network element is used to execute the method shown in the fourth aspect or any possible implementation of the fourth aspect; or, the session management function network element is used to execute the method shown in the fifth aspect or any possible implementation of the fifth aspect.

[0071] In the seventh aspect, the present application provides a communication method applied to a session management function network element, the method comprising: receiving second switching time information from an access and mobility management function network element, the second switching time information including the access time of at least one access network device corresponding to the terminal; based on the second switching time information, determining to switch the terminal to a second access network device; and requesting the user plane function network element to update the access network tunnel information of the terminal to the access network tunnel information of the second access network device serving the terminal.

[0072] Using the communication method provided in the present application, the session management function network element actively triggers the execution of the relevant process of switching the UE to the second access network device based on the second switching time information, without waiting for the synchronization message (such as the update request message) sent by the AMF about switching the terminal to the second access network device, thereby alleviating the communication pressure of the N11 interface and improving the switching efficiency.

[0073] In one possible implementation, before determining to switch the terminal to the second access network device based on the second switching time information, the method further includes: receiving access network tunnel information allocated to the terminal by other access network devices from the access and mobility management function network element, and the other access network devices include one or more access network devices of the at least one access network device other than the first access network device.

[0074] In a possible implementation manner, the access network tunnel information of the second access network device serving the terminal includes aggregated access network tunnel information allocated by the second access network device to the terminal.

[0075] In a possible implementation manner, the access network tunnel information of the second access network device serving the terminal includes access network tunnel information allocated by the second access network device to the first session of the terminal.

[0076] In a possible implementation manner, the access network tunnel information of the second access network device serving the terminal is allocated by the session management function network element.

[0077] In a possible implementation, after determining to switch the terminal to the second access network device based on the second switching time information, the method further includes: sending the access network tunnel information to the second access network device and / or the access and mobility management function network element.

[0078] In an eighth aspect, the present application provides a communication method, which is applied to an access and mobility management function network element, and the method includes: determining the second switching time information of the terminal, the second switching time information including the access time of at least one access network device corresponding to the terminal; and sending the second switching time information to the session management function network element.

[0079] In one possible implementation, the method further includes: obtaining access network tunnel information allocated by other access network devices to the terminal, the other access network devices including one or more access network devices other than the first access network device in the at least one access network device; and sending the access network tunnel information allocated by other access network devices to the terminal to the session management function network element.

[0080] In the ninth aspect, the present application provides a communication system, comprising an access and mobility management function network element and a session management function network element, wherein the access and mobility management function network element is used to execute the method shown in the eighth aspect or any possible implementation of the eighth aspect, and the session management function network element is used to execute the method shown in the seventh aspect or any possible implementation of the seventh aspect.

[0081] In one possible implementation, the system also includes a first access network device and a second access network device, wherein the first access network device is used to execute the method shown in the second aspect or any possible implementation of the second aspect, and the second access network device is used to execute the method shown in the first aspect or any possible implementation of the first aspect.

[0082] In the tenth aspect, the present application provides a communication method applied to a session management function network element, the method comprising: receiving second information from an access and mobility management function network element, the second information including the access time corresponding to the terminal accessing at least one access network device and the access network tunnel information allocated by the at least one access network device to the terminal; based on the second information, determining to switch the terminal to the second access network device; and requesting the user plane function network element to update the access network tunnel information of the terminal to the access network tunnel information of the second access network device serving the terminal.

[0083] Using the communication method provided in the present application, the session management function network element actively triggers the execution of the relevant process of switching the UE to the second access network device based on the second information, without waiting for the synchronization message (such as the update request message) sent by the AMF about switching the terminal to the second access network device, thereby alleviating the communication pressure of the N11 interface and improving the switching efficiency.

[0084] In a possible implementation, the second information includes second switching time information and access network tunnel information allocated by other access network devices to the terminal, and the second switching time information includes access time of at least one access network device corresponding to the terminal.

[0085] In a possible implementation, the second information includes a correspondence between an identifier of the session of the terminal, an access time when the terminal accesses a corresponding access network device, and access network tunnel information.

[0086] In the eleventh aspect, the present application provides a communication method, which is applied to an access and mobility management function network element, and the method includes: determining the second switching time information of the terminal; obtaining the access network tunnel information allocated to the terminal by other access network devices, and the other access network devices include one or more access network devices other than the first access network device in the at least one access network device; based on the second switching time information and the access network tunnel information allocated to the terminal by the other access network devices, sending second information to the session management function network element, the second information including the access time corresponding to the terminal accessing at least one access network device and the access network tunnel information allocated by the at least one access network device to the terminal.

[0087] In a possible implementation, the second information includes second switching time information and access network tunnel information allocated by other access network devices to the terminal, and the second switching time information includes access time of at least one access network device corresponding to the terminal.

[0088] In a possible implementation, the second information includes a correspondence between an identifier of the session of the terminal, an access time when the terminal accesses a corresponding access network device, and access network tunnel information.

[0089] In the twelfth aspect, the present application provides a communication system, comprising an access and mobility management function network element and a session management function network element, the access and mobility management function network element being used to execute the method shown in the eleventh aspect or any possible implementation of the eleventh aspect, and the session management function network element being used to execute the method shown in the tenth aspect or any possible implementation of the tenth aspect.

[0090] In one possible implementation, the system also includes a first access network device and a second access network device, wherein the first access network device is used to execute the method shown in the second aspect or any possible implementation of the second aspect, and the second access network device is used to execute the method shown in the first aspect or any possible implementation of the first aspect.

[0091] In the thirteenth aspect, the present application provides a communication device, comprising a unit for executing the method shown in any possible implementation of one or more of the first aspect, the second aspect, the third aspect, the fourth aspect, the fifth aspect, the seventh aspect, the eighth aspect, the tenth aspect, and the eleventh aspect.

[0092] In a fourteenth aspect, the present application provides a communication device comprising a processor, wherein the processor is used to execute the method shown in any possible implementation of one or more of the first aspect, the second aspect, the third aspect, the fourth aspect, the fifth aspect, the seventh aspect, the eighth aspect, the tenth aspect, and the eleventh aspect.

[0093] In the fifteenth aspect, the present application provides a communication device, including a logic circuit and an interface, wherein the logic circuit and the interface are coupled; the interface is used to input and / or output information, and the logic circuit is used to execute the method shown in any possible implementation of one or more of the first aspect, the second aspect, the third aspect, the fourth aspect, the fifth aspect, the seventh aspect, the eighth aspect, the tenth aspect, and the eleventh aspect.

[0094] In the sixteenth aspect, a computer-readable storage medium is used to store a computer program. When the computer program is executed, the method shown in any possible implementation of one or more of the first aspect, the second aspect, the third aspect, the fourth aspect, the fifth aspect, the seventh aspect, the eighth aspect, the tenth aspect, and the eleventh aspect is executed.

[0095] In the seventeenth aspect, the present application provides a computer program, which, when executed, enables the method shown in any possible implementation of one or more of the above-mentioned first aspect, second aspect, third aspect, fourth aspect, fifth aspect, seventh aspect, eighth aspect, tenth aspect, and eleventh aspect to be executed.

[0096] In aspect 18, the present application provides a computer program product, which includes a computer program or computer code, which, when running on a computer, enables the method shown in any possible implementation of one or more of the above-mentioned first aspect, second aspect, third aspect, fourth aspect, fifth aspect, seventh aspect, eighth aspect, tenth aspect, and eleventh aspect to be executed.

[0097] In the nineteenth aspect, an embodiment of the present application provides a chip system, which is applied to an electronic device, and the chip system includes one or more processors, which are used to call computer instructions to enable the electronic device to execute the method shown in any possible implementation method of one or more of the above-mentioned first aspect, second aspect, third aspect, fourth aspect, fifth aspect, seventh aspect, eighth aspect, tenth aspect, and eleventh aspect.

[0098] It is understood that the communication device, communication system, computer storage medium, computer program, computer program product, and chip system provided above are all used to perform the method shown in any implementation of the corresponding aspects of the embodiments of the present application. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects of the corresponding methods and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] FIG1 is a schematic diagram of the architecture of a communication system provided in an embodiment of the present application;

[0100] FIG2 is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0101] 3 is a schematic diagram of a handover process of a terminal switching to a target access network device in another communication method provided in an embodiment of the present application;

[0102] FIG4 is a schematic diagram of a method flow of a communication method provided in an embodiment of the present application;

[0103] FIG5A is a schematic diagram of different sources of core network tunnel information provided by an embodiment of the present application;

[0104] FIG5B is a schematic diagram of another embodiment of the present application regarding different sources of access network tunnel information;

[0105] FIG5C is a schematic diagram of another embodiment of the present application regarding different sources of terminal identification;

[0106] FIG6 is a schematic diagram of a method flow of another communication method provided in an embodiment of the present application;

[0107] FIG7 is a schematic diagram of a method flow of another communication method provided in an embodiment of the present application;

[0108] FIG8 is a schematic diagram of a method flow of another communication method provided in an embodiment of the present application;

[0109] FIG9 is a schematic diagram of a method flow of another communication method provided in an embodiment of the present application;

[0110] FIG10 is a schematic diagram of a method flow of another communication method provided in an embodiment of the present application;

[0111] FIG11 is a method flow diagram of another communication method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0112] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described below with reference to the accompanying drawings.

[0113] The terms "first" and "second" in the specification, claims, and drawings of this application are used only to distinguish different objects and are not used to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to the process, method, product, or device.

[0114] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in one or more embodiments of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It will be understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0115] In this application, "one or more (items)" refers to one or more, "multiple" refers to two or more, "at least two (items)" refers to two or three and more, and "and / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0116] The method provided in the embodiment of the present application can be applied to a satellite communication system under a regenerated payload mode in a non-terrestrial network (NTN). As shown in Figure 1, the communication system may include a terminal, a satellite, a ground station (also referred to as a gateway station, a signal gateway station), an access and mobility management function network element (AMF), a session management function network element (SMF), and a user plane function network element (UPF).

[0117] In a satellite communication system scenario operating in a regenerative payload mode, radio access network (RAN) equipment can be deployed on a satellite. For example, all or part of the functions of a base station (RAN) can be deployed on a satellite, and signaling interaction and user data transmission between base stations can be performed between satellites. The access network equipment described in this application can be a radio access network device. As standard technologies evolve, the access network device can also be network equipment of other standards, which is not limited in this application.

[0118] The air interface in Figure 1 is the wireless link between the terminal and the RAN; the Xn interface is the interface between RANs and RANs, mainly used for signaling interaction such as switching; the NG interface is the interface between RAN and AMF. In some descriptions, the NG interface is also called the N2 interface, which is used for signaling such as non-access stratum (NAS) of the interactive core network and user service data.

[0119] A terminal is a device with wireless transceiver functions. The terminal can communicate with an access network device (or also referred to as an access device) in a radio access network (RAN). For example, it can access the RAN in a satellite through an air interface and initiate calls, Internet access, and other services. A terminal may also be referred to as user equipment (UE), access terminal, terminal, subscriber unit, user station, mobile station, remote station, remote terminal, mobile device, user terminal, user agent, or user device. In one possible implementation, the terminal may be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; it may also be deployed on water (such as a ship, etc.). In one possible implementation, the terminal may be a handheld device with wireless communication capabilities, a vehicle-mounted device, a wearable device, a sensor, a terminal in the Internet of Things, a terminal in the Internet of Vehicles, a drone, a fifth generation (5G) network, or any form of terminal in future networks, etc., and the embodiments of the present application are not limited to this. Exemplarily, terminals can also communicate with each other through device-to-device (D2D), machine-to-machine (M2M), etc. The terminal shown in the embodiment of the present application can also be a device in the Internet of Things (IoT). The IoT network may include, for example, the Internet of Vehicles. Among them, the communication methods in the Internet of Vehicles system are collectively referred to as vehicle to other devices (vehicle to X, V2X, X can represent anything). For example, the V2X may include: vehicle to vehicle (V2V) communication, vehicle to infrastructure (V2I) communication, vehicle to pedestrian (V2P) communication or vehicle to network (V2N) communication, etc.

[0120] Ground stations can connect satellites to the RAN and the core network, forwarding signaling and service data between the satellite and the core network. Satellites can provide wireless access services to terminals, schedule wireless resources for accessed terminals, and offer reliable wireless transmission protocols and data encryption protocols. For example, in a regenerative payload mode, satellites can be base stations (RANs) that use artificial satellites and high-altitude aircraft as wireless communications, such as evolved NodeBs (eNBs) and next-generation NodeBs (gNBs).

[0121] The core network can include AMF, SMF, UPF, etc. Among them, AMF can be used to manage user access management, security authentication, and mobility management. UPF can be used to manage the transmission of user plane data, traffic statistics, etc.

[0122] In the embodiment of the present application, the satellite may be a medium Earth orbit (MEO) satellite or a low Earth orbit (LEO) satellite of a non-geostationary Earth orbit (NGEO), or a high altitude platform station (HAPS). The embodiment of the present application does not limit the specific type of satellite.

[0123] In some RAN deployments, the RAN may include a centralized unit (CU) and a distributed unit (DU). In other RAN deployments, the CU may be further divided into a CU-control plane (CP) and a CU-user plan (UP). In still other RAN deployments, the RAN may be an open radio access network (ORAN) architecture, etc. The embodiments of the present application do not limit the specific deployment of the RAN. For example, when the RAN is an ORAN architecture, the RAN shown in the embodiments of the present application may be an access network device or a functional module in the ORAN. In the ORAN system, the CU may also be referred to as an open (O)-CU, the DU may also be referred to as an O-DU, the CU-CP may also be referred to as an O-CU-CP, and the CU-UP may also be referred to as an O-CU-UP, etc. The RAN deployment methods listed here are only examples. With the evolution of standard technologies, RAN may have other deployment forms.

[0124] It is understandable that Figure 1 only shows one satellite and one ground station. In actual use, a multi-satellite and / or multi-ground station architecture can be adopted as needed. Among them, each satellite can provide services to one or more terminals, each satellite can correspond to one or more ground stations, each ground station can correspond to one or more satellites, and so on, which are not specifically limited in the embodiments of the present application. The method provided in the embodiments of the present application can be applied to the Internet of Things (IoT) system, the Internet of Vehicles (V2X), and the narrowband Internet of Things (NB-IoT) system; for example, it can be applied to the LTE frequency division duplex (FDD) system, the LTE time division duplex (TDD), the long term evolution (LTE) system, the fifth generation (5G) communication system, the sixth generation (6G) communication system or the future communication system, etc., which are not specifically limited in the embodiments of the present application.

[0125] The following describes the communication architecture between network elements included in the communication system used in this application:

[0126] Figure 2 is a schematic diagram of the communication network architecture between network elements included in a communication system according to an embodiment of the present application. It uses the 5G network architecture based on a service-oriented architecture in a non-roaming scenario defined in the 3GPP standardization process as an example. This network architecture can include three parts: the terminal part, the 5G system, and the data network (DN).

[0127] The terminal part may include a terminal 310, which may also be referred to as user equipment (UE). The terminal 310 in this application is a device with wireless transceiver functions, which can communicate with one or more core network (CN) devices (or may also be referred to as core devices) via an access network device (or may also be referred to as an access device) in a radio access network (RAN) 340. The terminal 310 may also be referred to as an access terminal, terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, user agent or user device, etc. The terminal 310 may be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; it may also be deployed on water (such as a ship, etc.); it may also be deployed in the air (such as on an airplane, balloon and satellite, etc.). Terminal 310 may be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a smart phone, a mobile phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), etc. Alternatively, terminal 310 may be a handheld device with wireless communication capabilities, a computing device, or other device connected to a wireless modem, an in-vehicle device, a wearable device, an unmanned aerial vehicle (UAV), or a terminal in the Internet of Things (IoT), the Internet of Vehicles (IoV), any terminal in a 5G network or future networks, a relay user device, or a terminal in a future evolved 5G system, etc. The relay user device may be, for example, a 5G residential gateway (RG). For example, the terminal 310 may be a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical care, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, etc. The embodiments of the present application do not limit the type or category of the terminal.

[0128] The 5G system may include: a network exposure function (NEF) 331, a network function repository function (NRF) 332, a policy control function (PCF) 333, a unified data management (UDM) 334, an application function (AF) 335, an authentication server function (AUSF) 336, an access and mobility management function (AMF) 337, a session management function (SMF) 338, a user plane function (UPF) 339, and a radio access network (RAN) 340. In the above 5G system, the parts other than the (radio) access network 340 can be referred to as the core network (CN) part or the core network part.

[0129] Data network DN 320, also known as a packet data network (PDN), is typically a network located outside the 5G system, such as a third-party network. For example, the 5G system can access multiple data network DNs 320, and multiple services can be deployed on data network DN 320 to provide data and / or voice services to terminal 310. For example, data network DN 320 can be the private network of a smart factory, where sensors installed in the workshop can be terminals 310. A control server for the sensors is deployed in data network DN 320, and the control server can provide services for the sensors. The sensors can communicate with the control server, obtain instructions from the control server, and transmit collected sensor data to the control server according to the instructions. For another example, data network DN 320 can be the internal office network of a company, where the mobile phones or computers of the company's employees can be terminals 310, and the employees' mobile phones or computers can access information, data resources, etc. on the company's internal office network. The terminal 310 can establish a connection with the 5G system through an interface provided by the 5G system (such as the N1 interface in Figure 2) and use data and / or voice services provided by the 5G system. The terminal 310 can also access the data network DN 320 through the 5G system and use the operator services deployed on the data network DN 320, and / or services provided by a third party. The third party may be a service provider other than the 5G system and the terminal 310, and may provide other data and / or voice services to the terminal 310. The specific form of the third party can be determined according to the actual application scenario and is not limited here.

[0130] For example, the following briefly introduces the network functions in the 5G system.

[0131] RAN 340 is a subnetwork of the 5G system and serves as the implementation system between the service nodes (or network functions) in the 5G system and the terminal 310. To access the 5G system, the terminal 310 first passes through RAN 340 and then connects to the service nodes in the 5G system through RAN 340. The access network device in the embodiments of the present application is a device that provides wireless communication functions for the terminal 310, and may also be referred to as an access device, RAN device, or network device. For example, the access device includes but is not limited to: the next generation node basestation (gNB) in the 5G system, the evolved node B (eNB) in the LTE system, the radio network controller (RNC), the node B (NB), the base station controller (BSC), the base transceiver station (BTS), the home evolved nodeB (or home node B, HNB), the base band unit (BBU), the transmission and receiving point (TRP), the transmitting point (TP), the small base station equipment (pico), the mobile switching center, or the network equipment in the future network, etc. It is understandable that the present application does not limit the specific type of access network equipment. In systems using different wireless access technologies, the names of devices with access network equipment functions may be different.

[0132] Optionally, in some deployments of access devices, the access device may include a centralized unit (CU) and a distributed unit (DU). In other deployments of access devices, the CU may be further divided into a CU-control plane (CP) and a CU-user plane (UP). In still other deployments of access devices, the access device may also be an open radio access network (ORAN) architecture. This application does not limit the specific deployment method of the access device.

[0133] The network open function NEF (also known as NEF network function or NEF network function entity) 331 is a control plane function provided by the operator. The NEF network function 331 opens the external interface of the 5G system to a third party in a secure manner. When the SMF needs to communicate with the network function of a third party, the NEF network function 331 can serve as a relay for communication between the SMF and the network entity of the third party. When the NEF network function 331 acts as a relay, it can translate the identification information of the contracted user and the identification information of the network function of the third party. For example, when the NEF network function 331 sends the subscriber's subscriber permanent identifier (SUPI) from the 5G system to a third party, the SUPI can be translated into its corresponding external identity (ID). Conversely, when the NEF network function 331 sends an external ID (network entity ID of a third party) to the 5G system, it can translate it into SUPI.

[0134] The network storage function NRF 332 can be used to maintain real-time information of all network function services in the network.

[0135] The policy control function PCF 333 is a control plane function provided by the operator, and is used to provide protocol data unit (PDU) session policies to the session management function network element SMF 338. Policies may include charging-related policies, QoS-related policies, and authorization-related policies.

[0136] Unified Data Management UDM 334 is a control plane function provided by the operator, which is responsible for storing information such as the subscriber permanent identifier (SUPI), security context, and subscription data of the subscribers in the 5G system. The subscribers of the above-mentioned 5G system may specifically be users who use the services provided by the 5G system, such as users who use the terminal chip cards of China Telecom, or users who use the terminal chip cards of China Mobile, etc. Exemplarily, the SUPI of the subscriber may be the number of the terminal chip card, etc. The above-mentioned security context may be data (cookie) or token stored on the local terminal (such as a mobile phone). The subscription data of the above-mentioned subscribers may be the supporting services of the terminal chip card, such as the traffic package of the mobile phone chip card, etc.

[0137] The application function AF 335 is used to perform data routing affected by the application, access network open functions, interact with the policy framework for policy control, etc.

[0138] The authentication server function AUSF 336 is a control plane function provided by the operator, which is usually used for level 1 authentication, that is, authentication between the terminal 310 (subscriber) and the 5G system.

[0139] The access and mobility management function network element AMF 337 is a control plane network function provided by the 5G system, which is responsible for the access control and mobility management of the terminal 310 to the 5G system, such as mobile state management, allocation of user temporary identity, authentication and authorization of users, etc.

[0140] The session management function network element SMF 338 is a control plane network function provided by the 5G system, responsible for managing the protocol data unit (PDU) session of the terminal 310. A PDU session is a channel for transmitting PDUs. The terminal needs to transmit PDUs to and from the DN 320 through the PDU session. The PDU session can be established, maintained, and deleted by the SMF 338. The SMF 338 includes session management (such as session establishment, modification, and release, including tunnel maintenance between the UPF 339 and the RAN 340), selection and control of the UPF 339, service and session continuity (SSC) mode selection, roaming and other session-related functions.

[0141] The user plane function (UPF) 339 is a gateway provided by the operator and serves as the gateway for communication between the 5G system and the DN 320. The UPF 339 includes user plane-related functions such as packet routing and transmission, packet inspection, service usage reporting, quality of service (QoS) processing, lawful interception, uplink packet inspection, and downlink packet storage.

[0142] The network functions in the 5G system shown in FIG2 may further include a network slice selection function (NSSF) (not shown in FIG2 ), which is responsible for determining a network slice instance, selecting an AMF network function, etc. The network functions in the 5G system shown in FIG2 may further include a unified data repository (UDR), etc. The embodiments of the present application do not limit other network functions included in the 5G system.

[0143] In Figure 2, Nnef, Nausf, Nnrf, Npcf, Nudm, Naf, Namf, Nsmf, N1, N2, N3, N4, and N6 are interface serial numbers. For example, the meanings of the above interface serial numbers can be found in the meanings defined in the 3GPP standard protocol, and this application does not limit the meanings of the above interface serial numbers. It should be noted that Figure 2 only uses terminal 310 as the UE for exemplary illustration, and the interface names between the various network functions in Figure 2 are only examples. In specific implementations, the interface names of the system architecture may also be other names, and this application does not limit this.

[0144] The mobility management network function in this application may be the AMF 337 shown in Figure 2, or may be other network functions in a future communication system having the above-mentioned access and mobility management function network element AMF 337. Alternatively, the mobility management network function in this application may also be a mobility management entity (MME) in an LTE system.

[0145] For convenience of explanation, in the embodiment of the present application, the access and mobility management function network element AMF 337 is referred to as AMF, the unified data management UDM 334 is referred to as UDM, and the terminal 310 is referred to as UE. That is, the AMF described later in the embodiment of the present application can be replaced with a mobility management network function, the UDM can be replaced with a unified data management, and the UE can be replaced with a terminal. It can be understood that other network functions not shown are also applicable to this replacement method.

[0146] The network architecture shown in Figure 2 (e.g., 5G network architecture) adopts a service-based architecture and universal interfaces. Traditional network element functions are split into several self-contained, self-managed, and reusable network function service modules based on network function virtualization (NFV) technology. The network architecture diagram shown in Figure 2 can be understood as a service-based 5G network architecture diagram in a non-roaming scenario. In this architecture, different network functions are combined in an orderly manner according to specific scenario requirements, which can achieve customization of network capabilities and services, thereby avoiding the deployment of dedicated physical networks for different services. Network slicing technology enables operators to respond to customer needs more flexibly and quickly, and supports the flexible allocation of network resources.

[0147] The following introduces the terms involved in the embodiments of this application.

[0148] (1) Access network tunnel information, core network tunnel information, and path switching messages

[0149] Access network tunnel information refers to the address of the access network device used when the UPF sends information related to the terminal (such as downlink data) to the access network device. Core network tunnel information refers to the address of the UPF used when the access network device sends information related to the terminal (such as uplink data) to the UPF. In some descriptions in this application, for the convenience of description, the tunnel information used to carry data about the terminal between the access network device and the user plane functional network element is described as the access network tunnel information or core network tunnel information of the access network device serving the terminal, specifically, it can be the access network tunnel information or core network tunnel information of the access network device and / or user plane functional network element serving the terminal or the session of the terminal. It should be noted that the specific definition of the access network tunnel information and the core network tunnel information depends on the protocol standard.

[0150] Generally, in the switching process of the terminal switching to the target access network device, after the air interface switching of the UE is completed between the source access network device and the target access network device, the target access network device sends a path switching message to the AMF. The path switching message is used to switch the path of the terminal. For example, the English name of the path switching message can be N2 path switch, path switch, or N2 path switch request, which is not limited in this document.

[0151] As an example, the path switching message is used to instruct (or trigger) AMF to request UPF through SMF to allocate core network tunnel information to the terminal, and to switch the N3 path used by UPF to send and / or receive relevant information of the terminal from the source access network device to the target access network device.

[0152] In addition, after the UPF allocates core network tunnel information to the terminal in response to the request of the SMF and sends it to the target access network device, the target access network device then sends the access network tunnel information allocated by the target access network device to the terminal to the UPF (specifically, the access network tunnel information can be sent to the UPF through the AMF and SMF), so that the target access network device and the UPF communicate based on the core network tunnel information and the access network tunnel information. Alternatively, in some other possible implementation methods, the path switching message can also carry the access network tunnel information allocated by the target access network device to the terminal, which is not limited in this document. However, it should be noted that by sending the access network tunnel information allocated by the target access network device to the terminal through the path switching message in step S303, the access network device does not need to wait for the UPF to allocate the core network tunnel information to the terminal and then allocate the access network tunnel information to the terminal, which can shorten the communication time involved in executing the switching process and improve the switching efficiency.

[0153] In the embodiment of the present application, the core network tunnel information and the access network tunnel information can serve the same session. The core network tunnel information and the access network tunnel information can serve only one session, or only sessions of the same slice, or only sessions of the same terminal accessing the same access network device, or sessions of all terminals accessing the same access network device, which is not limited in this document.

[0154] For ease of description, this document refers to tunnel information (core network tunnel information and access network tunnel information) that can only serve one session as session-granularity tunnel information; tunnel information that can only serve a session of one slice as slice-granularity tunnel information; tunnel information that can only serve sessions of the same terminal accessing the same access network device as UE-RAN-granularity tunnel information; and tunnel information that can serve sessions of all terminals accessing the same access network device as core network tunnel information and access network tunnel information as RAN-granularity tunnel information. Among them, tunnels of session granularity, slice granularity, UE-RAN granularity, and RAN granularity can all be referred to as aggregated tunnels. It should be noted that the service granularity of core network tunnel information and access network tunnel information is generally one-to-one corresponding. For example, if the core network tunnel information is session-granularity tunnel information, the access network tunnel information is also session-granularity tunnel information. However, this application does not limit the service granularity of core network tunnel information and access network tunnel information to only one-to-one corresponding, and this document does not make any limitation on this.

[0155] As another example, the time when the AMF receives the path switch message is the time when the terminal accesses the second access network device. For example, the AMF receives the path switch message of the terminal accessing RAN1 at time t1, and receives the path switch message of the terminal accessing RAN2 at time t2. The time period of RAN1 serving the terminal device is from t1 to t2.

[0156] (2) Terminal identification

[0157] In some possible implementations, based on communication security considerations, when the access network device and the AMF communicate about the terminal through the NG interface, the terminal identifier (UE ID) may not be directly used to identify the UE. Instead, the NG application protocol identifier (RAN UE NG Application Protocol Identity, RAN UE NGAP ID) allocated by the access network device to the UE and another private identifier allocated by the AMF to the UE are used to identify the UE to each other. For the sake of description, the RAN UE NGAP ID is referred to as the terminal identifier in this article.

[0158] In some possible implementations, in the switching process of the terminal, the path switching message sent by the target access network device to the AMF may also carry the terminal identifier assigned by the target access network device to the terminal, so as to enable or trigger the AMF to update the RAN UE NGAP ID locally stored in the AMF based on the terminal identifier.

[0159] The following introduces the technical background and technical problems solved by the embodiments of the present application.

[0160] In the regenerative transmission mode, the base station or part of the base station functions are deployed on the satellite, that is, the movement of the satellite will cause the wireless signal coverage of the radio access network (RAN) deployed on the satellite to change, and the satellite serving the UE needs to be replaced from the source access network device to the target access network device. Generally, low-orbit satellites are at a low altitude from the ground and move at a fast speed. It is estimated that for a certain position on the ground, the time interval required from one satellite moving directly above the ground to the next satellite moving directly above the ground is only about 3 minutes, which makes the switching process of the UE switching from accessing the source access network device to accessing the target access network device occur frequently. For the convenience of description below, the process of switching the UE from accessing the source access network device to accessing the target access network device is called the switching process. In some other description methods, it can also be called the Xn switching process, which is not limited in this article.

[0161] For example, in some other communication methods, each time the UE performs a handover process, the target access network device will perform a series of signaling interactions with the core network. As shown in Figure 3, after the air interface handover of the UE is completed between the source access network device and the target access network device (corresponding to step S302 in Figure 3), the target access network device sends an N2 path switching request for the UE to the AMF (corresponding to step S303 in Figure 3), thereby triggering the AMF to send a session update request to the SMF (corresponding to step S304 in Figure 3), and the SMF responds to the session update request and sends an N4 session modification request to the UPF (corresponding to step S305 in Figure 3), so as to request the UPF to allocate the core network tunnel information of the terminal. After the UPF allocates the core network tunnel information of the terminal, it sends the core network tunnel information allocated by the UPF to the terminal to the target access network device through steps S306-S308. And, after the target access network device receives the core network tunnel information of the terminal, it sends the access network tunnel information allocated by the target access network device to the terminal to the UPF through step S309.

[0162] This communication method, on the one hand, involves a lot of signaling interactions related to the target access network device obtaining the core network tunnel information of the terminal. It takes a certain amount of time for the target access network device to request and wait for the UPF to allocate core network tunnel information to the terminal. From the perspective of the switching process of a single UE, the switching efficiency needs to be improved. Furthermore, the core network serves a large number of UEs, and low-orbit satellites move at high speeds. Each UE will frequently switch to a different access network device. Both the same and different access network devices will frequently obtain the terminal's core network tunnel information from the UPF, which can easily cause network congestion. This leads to prominent issues such as the waiting time for the target access network device to wait for the user plane functional network element to allocate core network tunnel information to the terminal, and the efficiency of UE switching access network devices.

[0163] On the other hand, the UE frequently switches to different access network devices, and the NG interface between the access network device and the AMF needs to frequently process related signaling interactions about Xn switching (for example, steps S303, S308, and S309), which causes a signaling storm problem on the NG interface, and the communication pressure problem needs to be solved.

[0164] In view of this, an embodiment of the present application provides a communication method to improve the switching efficiency of the UE switching process.

[0165] Among them, in a communication method provided in an embodiment of the present application, after the first access network device determines that the UE switches to the second access network device based on the first switching time information, it sends a switching request message about the UE to the second access network device, and the first switching time information includes the access time corresponding to the UE accessing different RANs. After receiving the switching request message, the second access network device communicates with the UPF based on the switching request message and the core network tunnel information of the terminal stored in the second access network device. The AMF, based on the second switching time information, sends a first message about the UE to the SMF after determining that the UE switches to the second access network device. The second switching time information includes the access time corresponding to the UE accessing different RANs. The first message is used to request the SMF to update the access network tunnel information of the terminal's session to the access network tunnel information of the session of the terminal served by the second access network device.

[0166] Using the communication method provided in this application, after the second access network device receives the handover request message from the terminal, it communicates with the UPF based on the core network tunnel information of the terminal established between the second access network device and the UPF, without sending a path switch message to the AMF requesting the UPF to allocate core network tunnel information for the terminal. Thus, on the one hand, the process of the second access network device requesting and waiting for the UPF to allocate core network tunnel information for the terminal in the handover process is omitted, improving the handover efficiency of the terminal when frequently executing the handover process. On the other hand, the problem of communication pressure on the NG interface caused by the terminal frequently executing the handover process is avoided. For example, the second access network device does not need to send the N2 path switch request in step S303 of Figure 3 to the AMF, and the AMF does not need to send the N2 path switch request response shown in step S308 to the second access network device. On the other hand, the AMF cooperates with the execution of the corresponding process for the UE to handover to the second access network device based on the second handover time information (such as updating the RAN UE NGAP IP corresponding to the terminal and sending the first message corresponding to the terminal to the SMF), ensuring the consistency and integrity of the UE handover process.

[0167] As an example, the core network tunnel information of the terminal stored in the second access network device can be allocated by the UPF to the terminal when the terminal accesses the second access network device in the previous satellite operation cycle, or it can be allocated by the third access network device to the terminal and sent to the second access network device by the UPF before the second access network device receives the switching request message.

[0168] In other communication methods shown in Figure 3, the signaling interaction for sending the access network tunnel information allocated by the target access network device to the terminal to the UPF also requires a certain execution time. When multiple UEs frequently execute the switching process, the signaling interaction related to the access network tunnel information will also have a certain adverse impact on the switching efficiency.

[0169] In view of this, in the communication method provided in the present application, the SMF can also allocate access network tunnel information to the terminal, so that the AMF does not need to wait for the access network tunnel information allocated by the second access network device to the terminal, nor does it need to send the access network tunnel information allocated by the second access network device to the terminal to the SMF, thereby further improving the switching efficiency.

[0170] Alternatively, in the communication method provided in the present application, before the terminal currently accesses the second access network device, the access network tunnel information allocated to the terminal by the second access network device is sent to the AMF in advance. When the terminal accesses the second access network device, the second access network device no longer needs to send the access network tunnel information allocated to the terminal to the AMF. For example, when the terminal accesses the first access network device, the first access network device sends the access network tunnel information allocated to the terminal by multiple other access network devices to the AMF, thereby further improving the switching efficiency.

[0171] Alternatively, in the communication method provided in the present application, when the terminal last accesses the second access network device, the AMF receives the access network tunnel information allocated to the terminal sent by the second access network device, and stores the access network tunnel information. When the terminal accesses the second access network device next time, the second access network device no longer needs to send the access network tunnel information allocated to the terminal to the AMF, thereby further improving the switching efficiency.

[0172] In another communication method provided in an embodiment of the present application, after the AMF determines to switch the UE to the second access network device based on the second switching time information, it may not send the first message corresponding to the terminal to the SMF. Instead, the SMF actively triggers the sending of a second message to the UPF based on the second switching time information, requesting the UPF to update the access network tunnel information of the terminal's session. This further saves the execution time of a request and response, further improves communication efficiency, and reduces the communication pressure on the N11 interface caused by the terminal frequently executing the switching process.

[0173] In another communication method provided in an embodiment of the present application, after the SMF determines to switch the UE to the second access network device based on the second switching time information, it may not send the second message corresponding to the terminal to the UPF. Instead, the UPF actively triggers the update of the access network tunnel information of the terminal session based on the second switching time information. In this way, while alleviating the communication pressure on the NG interface and the N11 interface, the problem of communication pressure on the N4 interface caused by the terminal frequently executing the switching process is further reduced.

[0174] In this application, the N2 path switching message is also called the path switching message, the first message is also called the PDU session update request message or update request message, and the second message is also called the N4 session modification request. The specific names depend on the communication protocol standard and are not limited in this article.

[0175] The following describes a communication method provided by the present application in conjunction with Figure 4. The introduction of the first access network device, the second access network device, the AMF, the SMF, and the UPF in Figure 4 can refer to the relevant descriptions in Figures 1 and 2. As shown in Figure 4, the method includes:

[0176] S401: A first access network device determines to switch a terminal to a second access network device based on first switching time information of the terminal.

[0177] The first access network device may be an access network device currently accessed by the terminal, and the first access network device may be any access network device that can serve the terminal.

[0178] Among them, the first switching time information corresponding to the terminal may include the time when at least one access network device serves the terminal. The time when the access network device serves the terminal may refer to the service time period or the service end time. If the service time is the service time period, the first access network device determines to switch to the second access network device based on the end time in the service time period. If the service time is the service end time, the first access network device determines to switch the terminal to the second access network device based on the service end time. For example, when the service time is the service end time, assuming that at least one access network device includes RAN1 and RAN2, and the end time point of RAN1 serving the terminal is T1, and the end time point of RAN2 serving the terminal is T2, then the first switching time information corresponding to the terminal may include T1 corresponding to RAN1 and T2 corresponding to RAN2. Specifically, it may be expressed in the form of a list without limitation.

[0179] The at least one access network device may include all or part of the access network devices capable of serving the terminal.

[0180] Among them, the access network device that can serve the terminal refers to an access network device whose signal coverage range includes the location of the terminal during operation, and the at least one access network device includes the above-mentioned second access network device.

[0181] In some possible implementations, the satellite corresponding to the at least one access network device and the satellite corresponding to the first access network device belong to the same constellation; or, the satellite corresponding to the at least one access network device and the satellite corresponding to the first access network device have a direct and / or indirect inter-satellite link connection; or, the coverage range of each of the at least one access network device includes the location of the terminal.

[0182] In some possible implementations, the first access network device may determine the first switching time information based on the access time of the terminal to the at least one access network device in the satellite operation cycle (the previous satellite operation cycle). The satellite operation cycle refers to the period length corresponding to the satellite starting from any position in the orbit and returning to that position. The first access network device may store the access time corresponding to all or part of the access network devices that can serve the terminal accessed by the terminal in a complete satellite operation cycle. It should be noted that the access time can specifically be the service time period or the service end time. The access time and service time are just different ways of describing the same concept from different subject perspectives.

[0183] As an example, the first access network device obtains the first switching time information based on the satellite operating cycle and the access time corresponding to the terminal's access to the at least one access network device during the most recent satellite operating cycle. For example, if the satellite operating cycle is one hour, and the terminal accesses RAN1 from 09:00 to 09:05, accesses RAN2 from 9:06 to 09:10, ..., then the terminal's access to RAN1 in the next satellite operating cycle is from 10:00 to 10:05, and access to RAN2 is from 10:05 to 10:10, and so on. The at least one access network device may include all or part of the access network devices accessed by the terminal during a complete satellite operating cycle. For example, the first access network device may only store the access times of the terminal's access to RAN1 and RAN2 during the most recent satellite operating cycle, and not the access times of the terminal's access to other RANs. The first switching time information may be determined based on the access times corresponding to the terminal's access to RAN1 and RAN2.

[0184] As another example, the first access network device obtains the first switching time information based on the satellite operating cycle and the access time corresponding to the terminal accessing the first access network device in the most recent satellite operating cycle (the access time may be the service time period of the first access network device serving the terminal or the end time when the terminal ceases accessing the first access network device). For example, the satellite operating cycle is one hour, and the first access network device serves the UE for five minutes from the start time of the satellite operating cycle. When the service end time of the first access network device serving the terminal is reached, the first access network device initiates a switching request message regarding the terminal to the next access network device (the second access network device) in the satellite operating direction. For example, in the most recent satellite operating cycle, the terminal accessed the first access network device from 09:00 to 09:05. Then, in the satellite operating cycle next to the satellite operating cycle of the first access network device, the terminal accesses the first access network device from 10:00 to 10:05. In this next satellite operating cycle, the first access network device sends the switching request message to the second access network device at the end time corresponding to 10:05, and so on. Among them, the second access network device is the next access network device of the first access network device in the direction of satellite operation. The second access network device can also be determined after the first access network device interacts with multiple access network devices through inter-satellite links. There is no limitation on which access network device the second access network device is and the method of determining the second access network device.

[0185] It should be noted that the description that the satellite operating cycle is 1 hour and the duration that each access network device serves the UE for 5 minutes in one satellite operating cycle is only an example. The satellite operating cycle and the duration that each access network device serves the UE in one satellite operating cycle can also have other precisions, which is not limited in this article.

[0186] In some other possible implementations, the first access network device may determine the first switching time information based on the terminal's location and ephemeris information. The ephemeris information includes ephemeris information of satellites corresponding to one or more access network devices that can serve the terminal. Specifically, the first access network device may obtain the ephemeris information of a particular satellite to infer the location and signal coverage of the access network device corresponding to the satellite at any future time. Based on the terminal's location and the signal coverage of the access network device, the first access network device may predict the time at which the terminal will access each access network device to obtain the first switching time information. It is understood that the access network device corresponding to the satellite refers to the access network device deployed on the satellite.

[0187] As an example, the first access network device obtains the ephemeris information corresponding to other access network devices based on local storage and / or communication interaction with other access network devices. For example, the first access network device stores the ephemeris information corresponding to other access network devices. Alternatively, the first access network device obtains (or receives) the ephemeris information corresponding to other access network devices based on communication interaction with other access network devices. Alternatively, the first access network device obtains the ephemeris information corresponding to other access network devices based on a combination of local storage and communication interaction with other access network devices. Specifically, the first access network device locally stores the ephemeris information corresponding to some access network devices, and obtains the ephemeris information of the remaining access network devices based on communication interaction with other access network devices.

[0188] The satellite's ephemeris information includes one or more of the following: satellite coverage map, satellite coverage availability information, satellite motion information, and satellite-related information that corresponds to time. A satellite coverage map is a map divided into multiple grids, with each satellite corresponding to a coverage map at each moment. Grid points are marked on the coverage map, and bright grid points in the coverage map indicate signal coverage, while dark grid points indicate no signal coverage. The satellite's motion information may include information such as the satellite's orbital parameters, angular velocity, speed, and initial position. Satellite-related information that corresponds to time includes the satellite's position information and satellite capability information corresponding to the corresponding moment or time period.

[0189] In some other possible implementations, the first access network device may further obtain the first switching time information by receiving the first switching time information from the AMF. For example, the AMF may determine the first switching time information based on the access time of the terminal to the at least one access network device during a satellite operation cycle, or based on the terminal's location and ephemeris information, and then send the information to the first access network device.

[0190] In some other possible implementations, the AMF may also determine the second switching time information and send the second switching time information to the first access network device. The first access network device determines the first switching time information based on the second switching time information. For details, please refer to the detailed description in step S603 below.

[0191] It should be noted that the first switching time information corresponding to the terminal stored in each access network device can be consistent. For example, the switching time information stored in each access network device includes the time when certain specific access network devices among the at least one access network device serve the terminal. For another example, the switching time information stored in each access network device is the total switching time information, and the total switching time information includes the access time corresponding to the terminal accessing all access network devices that can serve the terminal, that is, the first switching time information includes the time corresponding to at least one access network device serving the terminal, and the at least one access network device is the terminal accessing all access network devices that can serve the terminal. In this scenario, after obtaining the above-mentioned first switching time information, the first access network device can also send the first switching time information to other access network devices that can serve the terminal, further improving the performance loss problem caused by other access network devices mechanically and repeatedly determining the switching time information corresponding to the terminal.

[0192] Alternatively, the first switching time information stored in each access network device and the terminal may be inconsistent. For example, the first switching time information stored in the first access network device only includes one of the access time (time point or time period) when the terminal accesses the adjacent access network device, the time period when the terminal accesses the first access network device, and the end time when the terminal terminates the connection with the first access network device, where the adjacent access network device is the next access network device of the first access network device in the direction of satellite operation.

[0193] In some possible implementations, the communication method provided in the present application is applicable to a scenario in which a terminal belonging to a target terminal type executes a handover process, and the terminal of the target terminal type is a stationary terminal. As an example, a stationary terminal refers to a terminal whose position does not change or whose moving speed is 0. It should be noted that the communication method provided in the present application is also applicable to a scenario in which a terminal type that does not belong to the target terminal type executes a handover process. However, in this scenario, when the position of the terminal changes, the access network device and the AMF side need to re-acquire the corresponding handover time information based on the position of the terminal.

[0194] S402: The first access network device sends a handover request message corresponding to the terminal to the second access network device.

[0195] Correspondingly, the second access network device receives the handover request message.

[0196] The handover request message is used to request that the terminal be handed over to the second access network device. Exemplarily, the handover request message carries context information of the terminal, and the context information of the terminal includes a first identifier of the terminal. In some possible implementations, the context information may also include an identifier of a PDU session of the terminal. The first identifier of the terminal may be an identifier of the terminal (UE ID), or the first identifier of the terminal may also be a cell radio network temporary identifier (C-RNTI) of the terminal.

[0197] S403: The second access network device communicates with the user plane function network element based on the handover request message and the core network tunnel information of the terminal stored in the second access network device.

[0198] Exemplarily, in response to the handover request message, the second access network device triggers establishment of a GTP-U tunnel for communication with the user plane function network element through the core network tunnel information of the terminal stored in the second access network device.

[0199] In one possible implementation, before the second access network device receives the handover request message from the first access network device, the method further includes: the second access network device receiving core network tunnel information of the terminal and storing the core network tunnel information. Receiving the core network tunnel information corresponding to the terminal by the second access network device includes: receiving the core network tunnel information of the terminal from the first access network device; or receiving the core network tunnel information of the terminal from a session management function network element.

[0200] That is, as shown in FIG5A , the core network tunnel information of the terminal stored in the second access network device may come from a third access network device (the third access network device may be the first access network device or another access network device). Specifically, the access network tunnel information of the terminal may be that when the terminal accesses the third access network device in a previous satellite operation cycle, the third access network device requests the UPF to allocate core network tunnel information for other access network devices to serve the terminal, the other access network devices including the second access network device, and the other access network devices including the second access network device; after the UPF allocates the corresponding core network tunnel information for the other access network device to serve the terminal, it sends it to the corresponding access network device among the other access network devices through the third access network device, and the other access network device stores the corresponding core network tunnel information after receiving the corresponding core network tunnel information.

[0201] Alternatively, reusing Figure 5A, the terminal's core network tunnel information stored in the second access network device may also come from the SMF. Specifically, the terminal's core network tunnel information was allocated by the UPF to the second access network device serving the terminal when the terminal accessed the second access network device during a previous satellite operation cycle and sent to the second access network device via the SMF. For example, before receiving the aforementioned handover request message, when the terminal accessed the second access network device during a previous satellite operation cycle, the second access network device sent a path switch message to the AMF, requesting the UPF to allocate core network tunnel information to the terminal through the AMF and SMF. After allocating the core network tunnel information to the terminal, the UPF sent it to the second access network device. After receiving the core network tunnel information, the second access network device stored it.

[0202] In this embodiment of the present application, after the second access network device receives the handover request message from the terminal, the second access network device does not send a path handover message to the AMF requesting the UPF to allocate core network tunnel information to the terminal. Instead, the second access network device communicates with the terminal based on the core network tunnel for the terminal established between the second access network device and the UPF. As a result, the handover process omits the process of the second access network device requesting and waiting for the UPF to allocate core network tunnel information to the terminal, thereby improving handover efficiency and avoiding network congestion caused by multiple terminals frequently executing handover processes.

[0203] S404: The AMF determines to switch the terminal to the second access network device based on the second switching time information corresponding to the terminal.

[0204] In an embodiment of the present application, the second switching time information includes the time when at least one access network device serves the terminal, the at least one access network device includes a second access network device, and the at least one access network device includes all or part of the access network devices that can serve the terminal.

[0205] In an embodiment of the present application, the first switching time information stored in the first access network device corresponds to the second switching time information stored in the AMF.

[0206] As an example, for the time when the same access network device (for example, access network device A) serves the terminal, the time when the access network device A serves the terminal recorded in the first switching time information is the same as the time when the access network device A serves the terminal recorded in the second switching time information.

[0207] As another example, for the access time corresponding to the same access network device (e.g., access network device A), the time recorded in the first switching time information for the access network device A to serve the terminal is earlier or later than the time recorded in the second switching time information for the access network device A to serve the terminal. For example, the time recorded in the first switching time information for the access network device A to serve the terminal is recorded as 1, and the time recorded in the second switching time information for the access network device A to serve the terminal is recorded as service time 2. The service time 1 is earlier than the service time 2. For example, the time difference between the two service times is the time of a satellite-to-ground transmission signaling, that is, although the second access network device does not send a signaling of a path switching message to the AMF, since the AMF needs to wait for the sending of the signaling when normally executing the switching process of the terminal switching to the second access network device to trigger the execution of the corresponding switching process, the time period of signaling transmission is within an acceptable error range. The time difference between the two service times, the earlyness or lateness of the two service times, and the length of the time difference are not limited in this document.

[0208] In some possible implementations, the AMF determines the second switching time information based on the access time at which the terminal respectively accesses at least one access network device during the satellite operation cycle. For details, refer to the above description regarding the determination of the first switching time information by the first access network device based on the access time at which the terminal respectively accesses at least one access network device during the satellite operation cycle, and will not be further elaborated here.

[0209] In some other possible implementations, the AMF determines the second switching time information based on the terminal's location and ephemeris information. Specifically, the AMF may obtain ephemeris information based on local configuration and / or communication interaction with the access network device to determine the second switching time information. For example, the AMF may obtain the corresponding ephemeris information by communicating with the access network device via an NG Set Request message. For details, please refer to the above description regarding the determination of the first switching time information by the first access network device based on the terminal's location and ephemeris information, which will not be detailed here.

[0210] In some other possible implementations, the AMF may also obtain the second switching time information based on the switching time information (first switching time information or second switching time information) from any access network device that can serve the terminal.

[0211] S405, AMF sends the first message corresponding to the terminal to SMF.

[0212] Accordingly, the SMF receives the first message.

[0213] The first message is used to update the access network tunnel information of the terminal.

[0214] Specifically, the first message can be used to request the SMF to update the access network tunnel information of the terminal session to the access network tunnel information corresponding to the second access network device.

[0215] In an embodiment of the present application, the AMF determines that the target access network device corresponding to the terminal and the current time in the second switching time information is the second access network device, and triggers the sending of the above-mentioned first message to the SMF, where the first message includes a request message for requesting the SMF to update the access network tunnel information of the terminal's session to the access network tunnel information corresponding to the second access network device. In some descriptions of the present application, the first message may also be referred to as an update request message (e.g., Nsmf_PDUsession_Update SMContext Request). The specific name of the first message depends on the protocol standard and is not limited in this document.

[0216] Referring to Figure 5B, in some possible implementations, the access network tunnel of the second access network device serving the terminal can be allocated by SMF; accordingly, the first message sent by AMF to SMF can carry the identifier of the second access network device, and the first message is used to request SMF to allocate first access network tunnel information to the terminal based on the identifier of the second access network device, and request SMF to update the access network tunnel information of the terminal to the first access network tunnel information.

[0217] Referring to Figure 5B, in some possible implementations, the access network tunnel of the terminal served by the second access network device may also be allocated by the second access network device. After allocating access network tunnel information to the terminal, the second access network device sends the access network tunnel information to the AMF, and the AMF determines the data content carried in the first message based on the access network tunnel information. For example, when the terminal accesses the second access network device in the previous satellite operation cycle, the second access network device sends the access network tunnel information allocated to the terminal to the AMF via a path switch message. The corresponding AMF stores the association between the access network tunnel information, the identifier of the second access network device, the identifier of the terminal, and the access time of the next access of the terminal to the second access network device. This allows the AMF to proactively trigger the sending of the first message to the SMF based on the identifier of the corresponding second access network device and the access network tunnel information, when the terminal accesses the second access network device again in the next satellite operation cycle.

[0218] Regarding the method for sending the access network tunnel information allocated by the second access network device to the terminal to the AMF, please refer to the relevant instructions on method 1 and method 2 below and will not be described in detail here.

[0219] It should be noted that regardless of whether the access network tunnel information of the service terminal is allocated by SMF or by the second access network device, the access network tunnel information can be access network tunnel information of session granularity, slice granularity, UE-RAN granularity, or RAN granularity.

[0220] As an example, the access network tunnel information allocated by the second access network device to the terminal belongs to the aggregated access network tunnel information of UE-RAN granularity or RAN granularity. The above-mentioned first message carries the identifier of the second access network device and the identifier of one or more sessions of the terminal. The first message is used to request the SMF to determine the aggregated access network tunnel information corresponding to the identifier of the second access network device, and update the access network tunnel information corresponding to the one or more sessions of the terminal to the aggregated access network tunnel information. For example, before the second access network device receives the handover request message corresponding to the terminal from the first access network device, the second access network device has sent the aggregated access network tunnel information of UE-RAN granularity or RAN granularity to the AMF, and after receiving the aggregated access network tunnel information, the AMF sends the correspondence between the aggregated access network tunnel information and the identifier of one or more sessions of the terminal to the SMF, and the SMF records the correspondence between the aggregated access network tunnel information and the identifier of one or more sessions of the terminal. Therefore, after receiving the first message from AMF carrying the identifier of the second access network device and the identifier of one or more sessions of the terminal, SMF can determine the aggregated access network tunnel information corresponding to the identifier of the second access network device, and update the access network tunnel information corresponding to the one or more sessions of the terminal to the aggregated access network tunnel information based on the aggregated access network tunnel information.

[0221] As another example, the access network tunnel information allocated by the second access network device to the terminal belongs to the access network tunnel information at the session granularity. The above-mentioned first message carries the identifiers of one or more sessions of the terminal and the access network tunnel information corresponding to the one or more sessions. The first message is used to request the SMF to update the access network tunnel information of the corresponding session in the terminal to the access network tunnel information of the second access network device serving the session.

[0222] Using the communication method provided in this application, during the terminal's Xn handover process, the second access network device communicates with the UPF based on the core network tunnel information stored in the second access network device. There is no need to send a path switch message to the AMF to request the UPF to allocate core network tunnel information to the terminal, thereby alleviating communication pressure on the NG interface and improving handover efficiency. Furthermore, the first access network device and the AMF perform corresponding tasks regarding the UE's handover to the second access network device based on the first handover time information and the second handover time information, respectively, to ensure the consistency and integrity of the handover process for the UE from the first access network device to the second access network device.

[0223] S406, SMF sends the second message corresponding to the terminal to UPF.

[0224] The second message is used to request the UPF to update the access network tunnel information corresponding to the terminal to the access network tunnel information corresponding to the second access network device.

[0225] Accordingly, the UPF receives the second message.

[0226] In an embodiment of the present application, the second message may also be referred to as an N4 session modification request. The second message carries the access network tunnel information of the terminal and does not carry indication information requesting the UPF to allocate the core network tunnel information of the terminal. Exemplarily, the second message specifically carries a first N4 session ID and second access network tunnel information. The first N4 session ID corresponds to one or more sessions of the terminal. The first N4 session ID is a private identifier between the SMF and the UPF that identifies one or more sessions of the same terminal. Based on the second message, the UPF modifies all access network tunnel information corresponding to the first N4 session ID to the second access network tunnel information.

[0227] In one possible implementation, after the second access network device receives the switching request message from the first access network device in step S402, the communication method shown in Figure 4 also includes: if the second access network device has stored the core network tunnel information of the terminal and the second access network device has allocated the access network tunnel information to the terminal, the second access network device does not send a path switching message to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

[0228] In an embodiment of the present application, as shown in Figure 5B, the access network tunnel information of the UPF and the second access network device serving the terminal may be allocated by the second access network device to the terminal, and may be sent to the AMF in two optional ways (way 1 and way 2) before the second access network device receives the above-mentioned switching request message corresponding to the terminal.

[0229] Method 1: The access tunnel information allocated by the second access network device to the terminal is sent to the AMF through a path switching message in the previous satellite operation cycle.

[0230] For example, before the second access network device receives the switching request message corresponding to the terminal, the terminal has accessed the second access network device in the previous satellite operation cycle, and the second access network device has sent a path switching message to the AMF carrying the access network tunnel information allocated by the second access network device to the terminal.

[0231] Method 2: The access network tunnel information allocated by the second access network device to the terminal is sent to the AMF through the third access network device.

[0232] The third access network device may be the first access network device or another access network device.

[0233] Exemplarily, before a first access network device sends a handover request message to a second access network device, the first access network device requests that other access network devices allocate access network tunnel information for the terminal, including the second access network device. The first access network device receives the access network tunnel information allocated by the other access network device for the terminal and sends the access network tunnel information allocated by the other access network device to the AMF. Consequently, when the terminal accesses the second access network device, the second access network device and the UPF use the access network tunnel information allocated in advance by the second access network device to serve the terminal, eliminating the need for the second access network device to send a path switch message carrying the access network tunnel information allocated by the second access network device to the AMF. In this embodiment of the present application, if at least one access network device in the first handover time information includes the first access network device, the other access network devices include one or more access network devices in the at least one access network device other than the first access network device. If the at least one access network device does not include the first access network device, the other access network devices are one or more of the at least one access network devices.

[0234] Based on method 1 or method 2, when the terminal accesses the second access network device again, the AMF or SMF requests the UPF to update the N3 path of the terminal based on the access network tunnel information allocated by the second access network device to the terminal in the previous satellite operation cycle, or based on the access network tunnel information allocated to the terminal by the second access network device in advance before receiving the above-mentioned switching request message. The second access network device no longer needs to send the access network tunnel information allocated by the second access network device to the terminal to the AMF through the NG interface, further improving the signaling storm problem of the NG interface, alleviating the communication pressure of the NG interface, and improving the switching efficiency.

[0235] Among them, in the above-mentioned method 1, the second access network device only needs to send the access network tunnel information allocated by the second access network device to the terminal to the AMF once. When the terminal accesses the second access network device next time, the second access network device will no longer send the tunnel information to the terminal. It sends it once for multiple times, which relieves the communication pressure of the NG interface and improves the switching efficiency. For example, when the terminal accesses the same second access network device n times (n is greater than or equal to 2), the signaling interaction between the second access network device and the AMF regarding the access network tunnel information is reduced from n signalings to one, which relieves the communication pressure of the NG interface; in addition, the access network tunnel information allocated by the second access network device to the terminal does not need to be forwarded to the AMF through the third access network device, which reduces the interaction between the access network devices.

[0236] In the above-mentioned method 2, the third access network device forwards the access network tunnel information allocated by other access network devices to the AMF. For example, the other access network devices are all or part of the access network devices that can serve the terminal except the third access network device. That is to say, the signaling interaction of all the access network devices (or the part of the access network devices) to send the access network tunnel information to the AMF is merged into the same message and sent. All the access network devices (including the second access network device) can send signaling containing the access network tunnel information to the AMF without going through the NG interface from beginning to end, further alleviating the communication pressure of the NG interface and improving the switching efficiency.

[0237] In an embodiment of the present application, the access network tunnel information and core network tunnel information of the terminal may be tunnel information at a session granularity, a slice granularity, a UE-RAN granularity, or a RAN granularity.

[0238] In some possible implementations, when the access network tunnel information allocated by the second access network device to the terminal belongs to a session-granular access network tunnel, the above-mentioned first access network device requests other access network devices to allocate access network tunnel information for the terminal, which may specifically include: during the process of the terminal establishing a first session through the first access network device, the first access network device requests other access network devices to allocate access network tunnel information for the first session, and the request may carry the identifier of the first session. For example, the terminal establishes session 1 and session 2 through the first access network device, then during the process of establishing session 1 and session 2, the first access network device requests other access network devices to allocate access network tunnel information for the session 1 and session 2, wherein request 1 (requesting the other access network device to allocate access network tunnel information for session 1) and request 2 (requesting the other access network device to allocate access network tunnel information for session 2) may be in the same message or may be two different request messages, which is not limited in this document.

[0239] With respect to the above-mentioned method 2, after a terminal accesses each access network device, the access network device does not need to request other access network devices to allocate access network tunnel information for the terminal. For example, if the first access network device accessed by the terminal is a preset access network device, the first access network device requests other access network devices to allocate access network tunnel information for the terminal. The preset access network device is a preset access network device used to request other access network devices to allocate access network tunnel information for the terminal. For example, the preset access network device is the first access network device accessed by the terminal, or the preset access network device is a specific access network device at a specific location during the satellite operation cycle, or the preset access network device is the access network device with which the terminal establishes a session.

[0240] In some other possible implementations, if the second access network device does not store the core network tunnel information of the terminal, or the second access network device does not allocate access network tunnel information to the terminal, a path switching message is sent to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

[0241] Exemplarily, after receiving the switching request message in step S802, the second access network device determines whether the second access network device stores the core network tunnel information of the terminal, and determines whether the second access network device has allocated the access network tunnel information to the terminal.

[0242] Among them, 1) when the second access network device determines that the core network tunnel information of the terminal is not stored and the second access network device has not allocated access network tunnel information to the terminal, it sends a path switching message to the AMF, thereby requesting the UPF to allocate core network tunnel information to the terminal through the AMF and SMF, and receiving the access network tunnel information allocated by the second access network device to the terminal and sending it to the UPF. For example, after the second access network device requests the UPF to allocate core network tunnel information to the terminal through the AMF and SMF, the second access network device allocates access network tunnel information to the terminal and sends it to the UPF through the AMF and SMF.

[0243] 2) When the second access network device determines that the core network tunnel information of the terminal is not stored and the second access network device has allocated access network tunnel information to the terminal, it sends a path switching message to the AMF, so that it requests the UPF to allocate core network tunnel information to the terminal through the AMF and SMF. After the second access network device receives the core network tunnel information of the terminal, the second access network device may or may not send the access network tunnel information allocated by the second access network device to the UPF, which is not limited in this document.

[0244] 3) When the second access network device determines that the core network tunnel information of the terminal is stored and the second access network device has not allocated the access network tunnel information for the terminal, the second access network device sends a path switch message to the AMF, and the second access network device may further perform step S403. As an example, the path switch message may carry the access network tunnel information allocated by the second access network device to the terminal. The path switch message is used to instruct the AMF to request the SMF to request the UPF to update the access network tunnel information of the terminal. The relationship between the path switch message and the core network tunnel information is described below: When the second access network device does not perform step S403, the path switch message may also be used to request the UPF to allocate new core network tunnel information for the terminal. Alternatively, when the second access network device performs step S403, the path switch message may not have the function of requesting the UPF to allocate new core network tunnel information for the terminal. This is not limited in this document. As another example, the path switching message does not carry the access network tunnel information allocated by the second access network device to the terminal. The path switching message is used to request the UPF to allocate new core network tunnel information to the terminal, and to enable the second access network device to allocate access network tunnel information to the terminal and send it to the UPF after receiving the core network tunnel information of the terminal. The second access network device and the UPF communicate based on the new core network tunnel information of the terminal and the access network tunnel information of the terminal).

[0245] 4) If the second access network device determines that it has stored the core network tunnel information of the terminal and has allocated the access network tunnel information to the terminal, it does not send a path switch message to the AMF. This omits the relevant request and waiting time, improves the handover efficiency of the terminal when frequently performing handover procedures, and reduces the communication pressure on the NG interface caused by the terminal frequently performing handover procedures.

[0246] In some other possible implementations, the access network tunnel information of the terminal served by the second access network device is allocated by the SMF. In this case, after receiving the handover request message in step S802, the second access network device determines whether the second access network device stores the core network tunnel information of the terminal, without determining whether the second access network device has already allocated the access network tunnel information for the terminal. If it is determined that the second access network device has already stored the core network tunnel information of the terminal, the second access network device executes S403. If it is determined that the second access network device does not store the core network tunnel information of the terminal, the second access network device sends a path switch message to the AMF, thereby requesting the UPF, through the AMF and the SMF, to allocate the core network tunnel information for the terminal.

[0247] In some other possible implementations, the path switching message may also carry a terminal identifier assigned by the second access network device to the terminal. The above-mentioned "if the second access network device has stored the core network tunnel information of the terminal, and the second access network device has allocated the access network tunnel information to the terminal, the second access network device does not send a path switching message to the access and mobility management function network element" specifically includes: when the second access network device has stored the core network tunnel information of the terminal, and the second access network device has allocated the access network tunnel information to the terminal, and the second access network device has allocated the terminal identifier to the terminal, the second access network device does not send a path switching message to the AMF.

[0248] In addition, the above-mentioned "if the second access network device does not store the core network tunnel information of the terminal, or the second access network device does not allocate access network tunnel information to the terminal, a path switching message is sent to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal" specifically includes: when the second access network device does not store the core network tunnel information of the terminal, or the second access network device does not allocate access network tunnel information to the terminal, or the second access network device does not allocate a terminal identifier to the terminal, the path switching message is not sent to the AMF.

[0249] Accordingly, in some possible implementations, the AMF determining in step S404 that the terminal is switched to the second access network device may specifically include: the AMF determining the target access network device corresponding to the terminal and the current time in the second switching time information as the second access network device, and updating the second identifier of the locally recorded terminal to the terminal identifier assigned to the terminal by the second access network device, where the second identifier is a private terminal identifier (also called RAN UE NGAP ID) used to identify the terminal between the AMF and the access network device to which the terminal accesses.

[0250] In some possible implementations, as shown in Figure 5C, the terminal identifier allocated by the second access network device to the terminal can be sent to the AMF in advance through the following two optional methods (Method 3 and Method 4). Here, in advance means before the second access network device receives the above-mentioned switching request message corresponding to the terminal, or before the AMF determines that the terminal switches to the second access network device based on the second switching time information.

[0251] Method 3: During the previous satellite operation cycle, the second access network device sends the terminal identifier allocated by the second access network device to the AMF through a path switching message.

[0252] Exemplarily, before the second access network device receives the switching request message from the first access network device in step S402, the terminal has accessed the second access network device in a previous satellite operation cycle, and the second access network device has sent a path switching message carrying the terminal identifier assigned to the terminal by the second access network device to the AMF in any satellite operation cycle in the previous satellite operation cycle (for example, when the terminal accessed the second access network device for the first time or the last time).

[0253] Method 4: Before the terminal accesses the second access network device (that is, before the second access network device receives the above-mentioned switching request message), the terminal identifier allocated by the second access network device to the terminal is sent to the AMF through the third access network device. The third access network device can be the first access network device or other access network device.

[0254] Exemplarily, before the first access network device sends a switching request message to the second access network device, the first access network device requests other access network devices to allocate a terminal identifier for the terminal, the other access network devices include the second access network device, and the other access network devices include all access network devices or part of the access network devices that can serve the terminal; the first access network device receives the terminal identifier allocated by the other access network device to the terminal, and sends the terminal identifier allocated by the other access network device to the terminal to the AMF.

[0255] It should be noted that, with respect to the above-described method 4, not every access network device needs to request other access network devices to assign a terminal identifier to the terminal after the terminal accesses it. For example, if the first access network device accessed by the terminal is a preset access network device, the first access network device requests other access network devices to assign a terminal identifier to the terminal. The preset access network device is a preset access network device used to request other access network devices to assign a terminal identifier to the terminal. For example, the preset access network device is the first access network device accessed by the terminal, or the preset access network device is a specific access network device at a specific location during the satellite's operating cycle.

[0256] Using the communication method provided in the present application, the first access network device sends a switching request message to the second access network device based on the first switching time information. After receiving the switching request message, the second access network device communicates with the UPF based on the stored core network tunnel information of the terminal. The AMF actively triggers the execution of the corresponding task regarding the UE switching to the second access network device based on the second switching time information (including sending a first message to the SMF to request updating the access network tunnel information of the terminal and updating the second identifier of the terminal), thereby ensuring the consistency and integrity of the air interface switching, the update of the RAN UE NGAP ID, and the N3 path update (including the update of the access network tunnel information and the core network tunnel information) in the switching process of the UE switching from the first access network device to the second access network device.

[0257] In some other possible implementations, the first access network device may also send a handover request message regarding the terminal to the second access network device based on changes in signal strength, without determining whether to send the handover request message regarding the terminal to the second access network device based on the first handover time information. Furthermore, the service time corresponding to each access network device included in the second handover time information corresponds to the time at which the first access network device sends the handover request message regarding the terminal to the corresponding access network device based on changes in signal strength. For example, the service time of the second access network device serving the terminal in the second handover time information corresponds to the time at which the first access network device sends the handover request message regarding the terminal to the second access network device based on changes in signal strength. The service time of the third access network device serving the terminal in the second handover time information corresponds to the time at which the second access network device sends the handover request message regarding the terminal to the third access network device based on changes in signal strength. Furthermore, if the terminal is stationary, even if the source access network device sends the handover request message regarding the terminal to the target access network device based on changes in signal strength instead of the first handover time information, it can still execute the relevant processes related to the terminal handover to the target access network device synchronously with the AMF, ensuring the consistency and integrity of the handover process.

[0258] The following introduces the specific application of the communication method provided in this application based on the distribution subject of the access network tunnel information used by the second access network device service terminal and the diversity of the tunnel information (core network tunnel information and access network tunnel information) service granularity, combined with Figures 6 to 11.

[0259] The following describes an application of the communication method provided in an embodiment of the present application, using the interaction diagram shown in Figure 6 as an example, in which a second access network device allocates access network tunnel information to a terminal, and in which the second access network device sends the access network tunnel information allocated to the terminal to the AMF via the above-mentioned method 1. As shown in Figure 6, the method includes the following steps:

[0260] S601: AMF determines second switching time information corresponding to the terminal.

[0261] In an embodiment of the present application, the second switching time information corresponds to the terminal (UE), and different UEs correspond to different switching time information. The second switching time information includes the identifier of at least one access network device and the time corresponding to the identifier of the access network device for serving the terminal, and in the second switching time information, there can be one or more service times corresponding to the identifier of the same access network device.

[0262] In an embodiment of the present application, the AMF may determine the second switching time information based on the access time corresponding to each access time of the terminal to at least one access network device during the satellite operation cycle, or determine the second switching time information based on the terminal's position and ephemeris information. Regarding how to determine the second switching time information based on the terminal's position and ephemeris information, the specific determination method may refer to the relevant description in step S404 above.

[0263] As an example, the trigger condition for the AMF to determine the second switching time information of the terminal may be that the AMF receives a session establishment request from the terminal to establish a first session.

[0264] As another example, the trigger condition for AMF to update (determine) the second switching time information of the terminal may be that the latest service time contained in the second switching time information corresponding to the terminal is later than the current time, and the difference between the latest service time and the current time is less than the preset duration.

[0265] As another example, the trigger condition for AMF to update (determine) the second switching time information of the terminal may also be that AMF completes a switching task of the terminal.

[0266] It should be noted that the AMF may also determine or update the second switching time information of the terminal based on other appropriate triggering conditions, which is not limited in this document.

[0267] As an example, if the AMF updates the second switching time information of the terminal once after executing a switching task of the terminal, the second switching time information determined by the AMF once corresponds to the next target access network device to be accessed by the terminal, that is, the above-mentioned at least one access network device is the next target access network device to be accessed by the terminal in the direction of satellite operation.

[0268] As another example, the second switching time information determined by the AMF at one time corresponds to at least two access network devices, and the at least two access network devices can be access network devices arranged in sequence with the access network device currently accessed by the terminal in the direction of satellite operation.

[0269] In the embodiments of the present application, the service time of an access network device serving a terminal can be a time or a service time period, which is not limited in this document. When the service time is a service time period, the switching time when the terminal switches from a first access network device to a second access network device is the end time of the service time period corresponding to the first access network device, or the start time of the service time period corresponding to the second access network device.

[0270] Exemplarily, taking the service time as the service time period and the identifier of the same access network device corresponding to two different service times as an example, the data specifically included in the second switching time information may be as shown in Table 1 below.

[0271] Table 1

[0272] S602, AMF sends second switching time information to the first access network device.

[0273] Correspondingly, the first access network device receives the second switching time information sent by the AMF.

[0274] S603: The first access network device determines first switching time information based on the second switching time information.

[0275] Exemplarily, after determining the second switching time information, the AMF may send the second switching time information to the first access network device, and the first access network device may determine the first switching time information based on the second switching time information. The service time of the access network device serving the terminal included in the first switching time information corresponds one-to-one with the service time of the access network device serving the terminal included in the second switching time information.

[0276] As an example, for the same access network device A, the service time corresponding to the access network device A in the first switching time information is one millisecond earlier than the service time corresponding to the access network device A in the second switching time. After receiving the first switching time information, the first access network device can determine the first switching time information based on the second switching time information and the first millisecond. The first millisecond can be the time for a satellite-to-ground signaling transmission.

[0277] S604: The first access network device sends a handover request message corresponding to the terminal to the second access network device based on the first handover time information corresponding to the terminal.

[0278] Correspondingly, the second access network device receives the handover request message.

[0279] In an embodiment of the present application, the first access network device determines to switch the terminal to the second access network device based on the first switching time information corresponding to the terminal, and sends a switching request message corresponding to the terminal to the second access network device.

[0280] As an example, the handover request message carries the context information of the terminal, and the context information of the terminal includes a first identifier of the terminal. Exemplarily, the first identifier may be a C-RNTI of the terminal.

[0281] S605: The second access network device determines whether the core network tunnel information of the terminal is stored.

[0282] In an embodiment of the present application, the core network tunnel information may be a session granularity, a slice granularity, a UE-RAN granularity or a RAN granularity, which is not limited in this document.

[0283] In an embodiment of the present application, when the core network tunnel information is UE-RAN granularity or RAN granularity, the second access network device executes step S606 when it is determined that the core network tunnel information of the terminal is not stored; the second access network device executes step S609 when it is determined that the core network tunnel information of the terminal is stored.

[0284] When the core network tunnel information is at session granularity, the second access network device determining whether the core network tunnel information of the terminal has been stored in step S605 includes: the second access network device determining whether the core network tunnel information corresponding to all sessions of the terminal has been stored. If the second access network device determines that the core network tunnel information corresponding to all sessions of the terminal has been stored, the second access network device executes step S606. If the second access network device determines that the core network tunnel information corresponding to all sessions of the terminal has not been stored, the second access network device executes step S609.

[0285] When the core network tunnel information is at a slice granularity, the second access network device determining whether the core network tunnel information of the terminal has been stored in step S605 includes: the second access network device determining whether the core network tunnel information corresponding to all slices of the terminal has been stored. If the second access network device determines that the core network tunnel information corresponding to all slices of the terminal has been stored, the second access network device executes step S606. If the second access network device determines that the core network tunnel information corresponding to all slices of the terminal has not been stored, the second access network device executes step S609.

[0286] S606: The second access network device sends a path switching message to the AMF.

[0287] Correspondingly, AMF requests UPF to allocate the core network tunnel information of the terminal based on the path switching request.

[0288] As an example, step S606 specifically includes: the second access network device sends a path switch message to the AMF, the path switch message being used to instruct (or trigger) the AMF to request core network tunnel information from the UPF through the SMF; the AMF, in response to the path switch message, sends an update request message to the SMF, the update request message carrying instruction information for instructing the SMF to request the UPF to allocate core network tunnel information for the terminal; and the SMF, in response to the update request message, sends an N4 session modification request to the UPF, the N4 session modification request including instructions for instructing the UPF to allocate core network tunnel information for the terminal. The specific implementation of step S606 may also refer to the protocol standard 3GPP TS23.502. The path switch message may also carry the terminal identifier (UE ID) and the terminal identifier (RAN UE NGAP ID) assigned to the terminal by the second access network device, so that the AMF updates the second identifier corresponding to the terminal to the terminal identifier assigned to the terminal by the second access network device, the second identifier being a private terminal identifier (also known as RAN UE NGAP ID) that identifies the terminal between the AMF and the access network device to which the terminal is switched.

[0289] Exemplarily, the AMF may store a first correspondence based on the terminal identifier assigned to the terminal by the second access network device carried in the path switching message, where the first correspondence includes the identifier of the terminal, the identifier of the access network device, and the correspondence between the terminal identifier assigned by the access network device to the terminal. For example, the data contained in the first correspondence is shown in Table 2 below. Based on the first correspondence, when the terminal accesses the second access network device next time, the AMF may actively trigger the update of the second identifier corresponding to the terminal based on the first switching time information and the first correspondence, without relying on the path switching request message sent by the second access network device to trigger.

[0290] Table 2

[0291] In some other possible implementations, the above-mentioned path switching message may not include the terminal identifier assigned by the second access network device to the terminal, but as shown in method 4 above, before the terminal accesses the second access network device, the terminal identifier assigned by the second access network device to the terminal is sent to the AMF through the third access network device.

[0292] In an embodiment of the present application, the UPF corresponding to the second access network device may be the same as or different from the UPF corresponding to the first access network device, and this document does not limit this.

[0293] S607, UPF sends the core network tunnel information allocated to the terminal to the second access network device.

[0294] Specifically, UPF can send the core network tunnel information corresponding to the second access network device and the terminal to the second access network device through AMF and SMF, or UPF can also send the core network tunnel information corresponding to the second access network device and the terminal to the first access network device through AMF and SMF, and then the second access network device sends the core network tunnel information allocated by UPF to the second access network device and the terminal to the first access network device. This document does not limit this.

[0295] In this embodiment of the present application, after receiving the core network tunnel information of the terminal, the second access network device stores the core network tunnel information of the terminal. Exemplarily, the second access network device stores the second correspondence shown in Table 3 below, which includes a correspondence between the terminal identifier and the core network tunnel information. Thus, in step S609, the second access network device can determine not to send a path switch message to the AMF based on this second correspondence.

[0296] Table 3

[0297] S608, the access network tunnel information of the terminal allocated by the second access network device is sent to SMF and UPF through AMF.

[0298] For details, please refer to the relevant handover process description in the standard 3GPP TS23.502.

[0299] In some other possible implementations, the second access network device may also send the access network tunnel information allocated by the second access network device to the UPF in step S606, omitting step S608. Specifically, the access network tunnel information allocated by the second access network device to the terminal is carried in the path switch message, update request message, and N4 session modification request in S606.

[0300] After receiving the access network tunnel information sent by the second access network device through the AMF, the SMF may store the correspondence between the terminal identifier, the second access network device identifier, and the access network tunnel information allocated by the second access network device to the terminal, and obtain a third correspondence, which includes the correspondence between the terminal identifier, the access network device identifier, and the access network tunnel information. Exemplarily, when the access network tunnel information is aggregated access network tunnel information at the UE-RAN granularity, the data included in the third correspondence is shown in Table 4 below. When the access network tunnel information is aggregated access network tunnel information at the RAN granularity, the data included in the third correspondence is shown in Table 5 below.

[0301] Based on this third correspondence, and in combination with the correspondence between the identifiers of all sessions of the terminal stored in the SMF and the identifier of the terminal, when the terminal accesses the second access network device next time, the SMF receives an update request message from the AMF carrying the identifier of the terminal and the identifier of the second access network device, the SMF can update the access network tunnel information of all sessions corresponding to the terminal to the access network tunnel information allocated to the terminal by the second access network device based on the third correspondence.

[0302] Table 4

[0303] Table 5

[0304] As another example, after receiving the access network tunnel information sent by the second access network device through the AMF, the SMF may also store the correspondence between the identifiers of one or more sessions, the identifier of the second access network device, and the access network tunnel information allocated by the second access network device to the terminal, to obtain a fourth correspondence. Exemplarily, the data contained in the fourth correspondence is shown in Table 6 below, and the fourth correspondence includes the identifier of the session, the identifier of the access network device, and the correspondence between the aggregated access network tunnel information. Based on this, when the terminal accesses the second access network device next time, when the SMF receives an update request message from the AMF carrying the identifiers of one or more sessions and the identifier of the second access network device, the SMF can update the access network tunnel information of the corresponding one or more sessions to the aggregated access network tunnel information allocated by the second access network device to the terminal based on the fourth correspondence.

[0305] Table 6

[0306] S609: Based on the core network tunnel information of the terminal stored, the second access network device determines not to send a path switching message to the AMF.

[0307] In an embodiment of the present application, when the second access network device determines that the core network tunnel information of the terminal has been stored, it does not send a path switching message to the AMF, thereby improving the signaling storm problem of the NG interface and improving the switching efficiency.

[0308] S610: The AMF determines to switch the terminal to the second access network device based on the second switching time information.

[0309] As an example, the AMF determines, based on the second switching time information, that the terminal is switched to the second access network device. Specifically, the AMF determines, based on the second switching time information shown in Table 1 above, that the identifier of the target access network device of the terminal corresponding to the current time is the identifier of the second access network device. Furthermore, based on the first correspondence shown in Table 2 above, the AMF determines the terminal identifier assigned to the terminal by the second access network device, and updates the locally stored second identifier of the terminal to the terminal identifier assigned to the terminal by the second access network device.

[0310] S611, AMF sends the first message to SMF.

[0311] The first message is used to request the SMF to update the access network tunnel information of the terminal's session to the access network tunnel information allocated to the terminal by the second access network device.

[0312] Correspondingly, the SMF receives the first message and updates the access network tunnel information of the terminal's session to the access network tunnel information allocated to the terminal by the second access network device.

[0313] In an embodiment of the present application, the first message in step S611 carries indication information for instructing the SMF to update the access network tunnel information of the terminal, but does not include indication information for instructing the SMF to request the UPF to allocate core network tunnel information for the terminal.

[0314] As an example, when the SMF stores the above-mentioned third correspondence in step S607, the first message in S611 also carries the identifier of the terminal and the identifier of the second access network device. After receiving the first message, the SMF determines the access network tunnel information corresponding to the identifier of the second access network device and the identifier of the terminal based on the third correspondence shown in Table 4 or Table 5 above, and updates the access network tunnel information of all sessions of the terminal to the access network tunnel information, and executes step S612 based on the access network tunnel information.

[0315] As another example, when the SMF stores the above-mentioned fourth correspondence in step S607, the first message in S611 also carries the identifier of one or more sessions. After receiving the first message, the SMF updates the access network tunnel information of the one or more sessions to the access network tunnel information allocated by the second access network device to the terminal based on the fourth correspondence, and executes step S612 based on the access network tunnel information.

[0316] In some possible implementations, the first message sent by the AMF to the SMF may also carry the capability information of the second access network device. Exemplarily, the second switching time information corresponding to the above Table 1 may also include the capability information of the access network device corresponding to the identifier of the access network device. Based on the second switching time information, the AMF determines to switch the terminal to the second access network device, and determines the identifier of the second access network device, the capability information of the second access network device, and the identifier of the terminal carried in the first message. Among them, the capability information of the access network device includes one or more of the tracking area list (supported TA list) supported by the access network device, the supported data network name / single network slice selection support information (supported DNN / S-NSSAI), and the supported QoS flows. For example, the SMF can set the access network tunnel information of all sessions of the terminal based on the capability information of the second access network device and the access network tunnel information allocated by the second access network device to the terminal, and release the QoS flows not supported by the second access network device.

[0317] In an embodiment of the present application, to avoid a situation where the AMF receives a path switch message in step S606 and actively triggers the execution of step S610 based on the second switching time information, thereby causing an unknown program error, as an example, after determining to switch the terminal to the second access network device, the AMF may, based on the fact that the terminal identifier assigned to the terminal by the second access network device is not stored in the first correspondence, determine not to execute step S611, but instead execute the above steps S606-S608 based on the path switch message sent by the second access network device. Alternatively, as another example, the AMF records indication information indicating whether the second access network device has assigned a terminal identifier and an access network tunnel to the terminal. If the AMF determines based on this indication information that the second access network device has assigned a terminal identifier and access network tunnel information to the terminal, the AMF executes the above steps S610 and S611 based on the second switching time information.

[0318] S612, SMF sends a second message to UPF.

[0319] In this embodiment of the present application, the second message in step S612 carries the access network tunnel information of the terminal, and does not carry the instruction information requesting the UPF to allocate the core network tunnel information of the terminal. For an explanation of the second message, please refer to the relevant description in step S406 and will not be described in detail here.

[0320] S613, the second access network device communicates with the UPF based on the core network tunnel information and access network tunnel information of the terminal.

[0321] In an embodiment of the present application, after step S608 or step S612, the second access network device can communicate based on the core network tunnel information and access network tunnel information of the terminal to serve the session of the terminal.

[0322] In an embodiment of the present application, when the terminal accesses the second access network device for the first time, referring to steps S606-S608, the second access network device requests the UPF to allocate core network tunnel information to the terminal through a path switching message, and sends the terminal identifier allocated by the second access network device to the terminal to the AMF through a path switching request message; after the second access network device receives the core network tunnel information of the terminal, it allocates access network tunnel information to the terminal and sends the access network tunnel information to the AMF, and the AMF stores the above-mentioned first correspondence based on the path switching message, and sends the access network tunnel information to the SMF, and the SMF stores the above-mentioned third correspondence based on the update request message.

[0323] When the terminal accesses the second access network device again, referring to steps S609 to S612, based on the fact that the second access network device has stored the core network tunnel information of the terminal, the second access network device no longer sends a path switching message to the AMF, thereby reducing the request and waiting time for the core network tunnel information, improving the signaling storm problem of the NG interface caused by the terminal frequently executing the switching process, and improving the switching efficiency. In addition, based on the second switching time information and the first correspondence, the AMF actively updates the second identifier of the terminal and sends the first message of the terminal to the SMF. The SMF updates the N3 path information of the terminal based on the first message and the third correspondence, ensuring the integrity of the related air interface switching, N2 information update, and N3 interface switching when the terminal switches from the first access network device to the second access network device, thereby ensuring the normal Internet access function of the terminal after the switching process is executed.

[0324] Among them, air interface switching refers to switching the terminal from communicating with the core network through the air interface corresponding to the first access network device to communicating with the core network through the air interface corresponding to the second access network device based on the switching request message; N2 information update refers to switching the AMF through the NG interface service terminal corresponding to the first access network device to the NG interface service terminal corresponding to the second access network device based on the path switching message, and the N2 information update includes the update of the second identifier; N3 interface switching refers to switching the UPF through the N4 interface service terminal corresponding to the first access network device to the N4 interface service terminal corresponding to the second access network device based on the second message.

[0325] The following, in conjunction with the interaction diagram shown in FIG7 , takes the case where the terminal identifier and access network tunnel information allocated by the second access network device to the terminal are pre-sent to the AMF through the combination of the above-mentioned method 2 and method 4, and the type of the tunnel information (access network tunnel information and core network tunnel information) is tunnel information of session granularity as an example to introduce an application of the communication method provided in an embodiment of the present application. It should be noted that if the second access network device and the AMF can directly identify the terminal based on the UE ID without the RAN UE NGAP ID identifier, the communication method shown in FIG7 may also not include the scheme for terminal identification. It should be pointed out that other access network devices in the specification can be replaced with the second access network device without limitation.

[0326] As shown in FIG7 , the method includes the following steps:

[0327] S701: A terminal sends a session establishment request for a first session to a first access network device.

[0328] Correspondingly, the first access network device receives the session establishment request.

[0329] In the embodiment of the present application, the access network device currently accessed by the terminal is the first access network device, and the first session may be any session established by the terminal through the first access network device.

[0330] In this embodiment of the present application, the session establishment request serves as a triggering condition for the first access network device to request another access network device to allocate access network tunnel information and a terminal identifier to the terminal. That is, whenever the terminal establishes a new session through the first access network device, upon receiving the session establishment request, the first access network device triggers execution of step S702.

[0331] S702: The first access network device requests other access network devices to allocate access network tunnel information and a terminal identifier to the terminal.

[0332] The other access network device includes a second access network device, which is an access network device adjacent to the first access network device in the positive direction of the satellite operation direction. For the description of the other access network device, please refer to the relevant description in step S403 above and will not be described in detail here.

[0333] S703: The other access network devices respectively send the access network tunnel information and the terminal identifier allocated to the terminal to the first access network device.

[0334] Correspondingly, the first access network device receives the access network tunnel information and the terminal identifier allocated to the terminal by other access network devices.

[0335] In an embodiment of the present application, the first access network device may simultaneously request other access network devices to allocate access network tunnel information and a terminal identifier to a terminal through the same request message. Alternatively, the first access network device's request for other access network devices to allocate a terminal identifier to the terminal and the request for other access network devices to allocate access network tunnel information to the terminal may be included in different request messages, which are not limited herein.

[0336] As an example, a first access network device sends a first request and a second request to other access network devices, respectively, the first request being used to request that the other access network device allocate access network tunnel information for one or more sessions currently newly created by the terminal, and the second request being used to request that the other access network device allocate a terminal identifier for the terminal. Based on the first request, the other access network device allocates access network tunnel information for the one or more sessions of the terminal, and based on the second request, the other access network device allocates a terminal identifier for the terminal. The first access network device receives a first response sent by the other access network device, respectively, the first response corresponding to the first request, the first response carrying the access network tunnel information allocated by the corresponding access network device to the terminal, and the first access network device receives a second response sent by the other access network device, respectively, the second response corresponding to the second request, and the second response carrying the terminal identifier allocated by the corresponding access network device to the terminal.

[0337] As another example, the first access network device sends a third request to each other access network device (the third request includes the request content of the first request and the second request), and the third request is used to request the other access network device to allocate a terminal identifier for the terminal and to allocate access network tunnel information for one or more newly created sessions of the terminal. For example, the third request carries the identifiers of the one or more newly created sessions of the terminal and the first identifier of the terminal. Based on the third request, the other access network device allocates access network tunnel information for each session of the terminal and allocates a terminal identifier for the terminal; the first access network device receives a third response sent by the other access network device, and the third response carries the first identifier of the terminal, the terminal identifier allocated to the terminal by the access network device corresponding to the first response, and the access network tunnel information allocated to each session of the terminal by the access network device corresponding to the first response.

[0338] In an embodiment of the present application, when the first access network device requests other access network devices to allocate access network tunnel information and terminal identifiers to the terminal through the above-mentioned third request, the session establishment request in the above-mentioned step S701 can be used as a request trigger condition for triggering the first access network device to send a third request to other access network devices. Wherein, each time any one of the other access network devices responds to the third request of the same terminal, the terminal identifier allocated to the terminal is the same. Alternatively, when any one of the other access network devices responds to the third request of the same terminal, if it is determined that the terminal identifier has been allocated to the terminal, the terminal identifier is no longer allocated to the terminal, and the third response sent by the access network device to the AMF carries the access network tunnel information allocated by the access network device to the terminal, but does not carry the terminal identifier allocated by the access network device to the terminal.

[0339] It should be noted that the embodiment of the present application uses the above-mentioned session establishment request as an example of a request trigger condition for triggering the first access network device to request other access network devices to allocate access network tunnel information and terminal identification to the terminal through a third request. The request trigger condition corresponding to the third request may also be other conditions. For example, the request trigger condition may also be that the first access network device receives a session establishment acceptance message sent by the AMF.

[0340] In an embodiment of the present application, when the first access network device requests other access network devices to allocate access network tunnel information and terminal identification to the terminal through the above-mentioned first request and second request, the request trigger condition corresponding to the first request and the second request may be the session establishment request in the above-mentioned step S701, but is not limited to this. For example, the request trigger condition of the first request and the second request may also be that the first access network device receives the session establishment acceptance message sent by the AMF. For example, the request trigger condition of the second request may also be: the first access network device is a preset access network device. For the introduction of the preset access network device, please refer to the relevant description above.

[0341] Understandably, by using the third request, the first access network device requests the other access network device to allocate access network tunnel information and a terminal identifier for the terminal. This allows two tasks to be processed in a single message, achieving twice the result with half the effort. This reduces signaling interaction on the Xn interface between the first and second access network devices, thereby lowering performance losses. The first access network device requests the other access network device to allocate access network tunnel information and a terminal identifier for the terminal through the first and second requests, respectively. This decouples the two distinct tasks, simplifies program design, and can significantly reduce program response time.

[0342] S704, the first access network device sends the first information to the AMF.

[0343] The first information may include access network tunnel information and a terminal identifier allocated to the terminal by other access network devices.

[0344] Accordingly, the AMF receives the first information.

[0345] Exemplarily, the first information includes a terminal identifier assigned by the second access network device to the terminal, an identifier of the access network device, an identifier of each session of the terminal, access network tunnel information corresponding to the identifier of each session of the terminal assigned by the second access network device to the terminal, and a terminal identifier assigned by the first access network device to the terminal, wherein the first information carries the terminal identifier assigned by the first access network device to the terminal to indicate to the AMF the terminal to which the first information corresponds.

[0346] In an embodiment of the present application, after receiving the first information, the AMF may store a fifth correspondence, which is used to record the terminal identifier assigned by the access network device to the terminal and the access network tunnel information assigned to each session of the terminal. Exemplarily, the fifth correspondence includes the identifier of the terminal, the identifier of the second access network device, the terminal identifier assigned by the second access network device to the terminal, the identifier of each session of the terminal, and the correspondence between the access network tunnel information corresponding to the identifier of each session of the terminal. For example, the data corresponding to the same terminal contained in the fifth correspondence is shown in Table 7 below. The fifth correspondence may include data corresponding to one terminal, or data corresponding to multiple terminals, which is not limited in this document.

[0347] Table 7

[0348] In some possible implementations, the first information also includes the access network tunnel information allocated by the first access network device for the first session (the first session is currently a newly established session). When establishing the first session, the first access network device does not send a path switch message carrying the access network tunnel information allocated by the first access network device for the first session to the AMF. After receiving the first information, the AMF proactively sends a first message regarding the first session to the SMF based on the fact that the first information contains the access network tunnel information allocated by the access network device currently accessed by the terminal (i.e., the first access network device) for the terminal's session. The first message carries the identifier of the first session and the access network tunnel information allocated by the first access network device for the first session. Thus, the access network tunnel information allocated by the first access network device for the newly established first session is included in the first information and sent to the AMF, rather than being sent to the AMF via a path switch message. This further improves the signaling storm problem of the NG interface and improves switching efficiency.

[0349] S705, AMF requests UPF to allocate core network tunnel information to the terminal.

[0350] As an example, the indication information for instructing the AMF to request the UPF through the SMF to allocate core network tunnel information for the terminal can be sent to the AMF in the same message as the first information in step S704. As another example, the indication information and the first information may not be included in the same message, that is, the first access network device sends the indication information to the AMF through another message.

[0351] Specifically, the AMF may instruct the SMF to request the UPF to allocate core network tunnel information for the terminal through an update request message, and the update request message carries indication information for instructing the SMF to request the UPF to allocate core network tunnel information for the terminal. In response to the update request message, the SMF requests the UPF to allocate core network tunnel information for the terminal through an N4 session modification request, and the N4 session modification request includes indication information for instructing the UPF to allocate core network tunnel information for the terminal.

[0352] In an embodiment of the present application, the AMF may request the UPF to allocate core network tunnel information for each session of the terminal. For example, the terminal establishes session 1 and session 2 through the first access network device, and the AMF sends update request message 1 and update request message 2 to the UPF through the SMF. The update request message 1 is used to request the UPF to allocate core network tunnel information for session 1, and the update request message 2 is used to request the UPF to allocate core network tunnel information for session 2.

[0353] Alternatively, the AMF may also request the UPF to allocate core network tunnel information for all sessions of the terminal at one time. For example, the terminal establishes session 1 and session 2 through the first access network device, and the AMF sends an update request message 3 to the UPF through the SMF. The update request message 3 is used to request the UPF to allocate core network tunnel information for session 1 and session 2.

[0354] In one example, after receiving the above request, UPF allocates core network tunnel information to the terminal, where the core network tunnel information corresponds to other access network devices; further, UPF sends the allocated core network tunnel information to the first access network device, for example, through AMF or SMF.

[0355] Among them, the request can carry information of other access network devices (for example, identification, or address, etc.), and then the UPF allocates different core network tunnel information to the terminal for different access network devices. For example, the information of other access network devices includes the second access network device and the third access network device. For the second access network device, the UPF allocates the second core network tunnel information to the terminal, and for the third access network device, the UPF allocates the third core network tunnel information to the terminal.

[0356] The second core network tunnel information is used to establish a tunnel between the UPF and the second access network device for the terminal when the terminal accesses the second access network device, and the tunnel is used to carry the data of the terminal. The third core network tunnel information is used to establish a tunnel between the UPF and the third access network device for the terminal when the terminal accesses the third access network device, and the tunnel is used to carry the data of the terminal.

[0357] It can be seen that the core network tunnel information corresponds to other access network devices. It can be understood that the second core network tunnel information corresponds to the second access network device, and the third core network tunnel information corresponds to the third access network device.

[0358] S706, UPF sends the core network tunnel information allocated to the terminal to the corresponding access network device.

[0359] Correspondingly, the access network device receives the core network tunnel information allocated by the UPF to the terminal.

[0360] In one example, UPF can send the core network tunnel information allocated to the terminal to the first access network device through AMF and SMF, and the first access network device then sends the core network tunnel information to other access network devices (including the second access network device and the third access network device) accordingly. For example, the second core network tunnel information and the third core network tunnel information are sent to SMF, SMF sends the second core network tunnel information and the third core network tunnel information to AMF, AMF then sends the second core network tunnel information and the third core network tunnel information to the first access network device, and the first access network device then sends the second core network tunnel information to the second access network device, and sends the third core network tunnel information to the third access network device.

[0361] In another example, UPF can directly send the core network tunnel information to the corresponding access network device through AMF and SMF, for example, send the second core network tunnel information to SMF, and then SMF forwards it to AMF, and then AMF forwards it to the second access network device.

[0362] Exemplarily, in the process of the terminal accessing the first access network device and establishing a first session based on the first access network device (or it can also be understood as whenever the terminal establishes a session), the UPF allocates corresponding core network tunnel information to the second access network device to serve the newly established session and sends it to the second access network device. The second access network device receives and stores the core network tunnel information, so that in step S709, the second access network device can not send a path switching message to the AMF based on the stored core network tunnel information of the terminal.

[0363] It should be noted that the above-mentioned other access network devices may include only one access network device, for example, the second access network device; in addition, the above-mentioned core network tunnel information allocated to the terminal can be replaced with the core network tunnel information allocated to the first session in step S701, without limitation.

[0364] S707: AMF obtains the second switching time information corresponding to the terminal.

[0365] S708: The first access network device sends a handover request message corresponding to the terminal to the second access network device based on the first handover time information corresponding to the terminal.

[0366] Correspondingly, the second access network device receives the handover request message.

[0367] Detailed descriptions of the second switching time information, the first switching time information, and the switching request message can be found in steps S601 to S604 in FIG6 , or in steps S401 and S404 in FIG4 , and are not described in detail here.

[0368] S709. The second access network device determines not to send a path switching message to the AMF based on the stored core network tunnel information of the terminal.

[0369] Exemplarily, after receiving the switching request message from the terminal, the second access network device may not determine whether the second access network device stores the core network tunnel information of the terminal, but may directly not send the corresponding path switching message to the AMF in response to the switching request message.

[0370] S710: The AMF determines to switch the terminal to the second access network device based on the second switching time information.

[0371] Exemplarily, the AMF determines that the identifier of the target access network device of the terminal corresponding to the current time is the identifier of the second access network device based on the second switching time information; then, based on the identifier of the second access network device and the above-mentioned fifth correspondence stored locally, it determines the terminal identifier assigned to the terminal by the second access network device, and updates the second identifier of the terminal recorded locally to the terminal identifier assigned to the terminal by the second access network device (which can also be understood as updating the N2 information).

[0372] S711, AMF sends the first message to SMF.

[0373] The first message may carry access network tunnel information allocated by the second access network device to the terminal.

[0374] Accordingly, the SMF receives the first message.

[0375] In an embodiment of the present application, the first message may also be an update request message. The first message does not include indication information for instructing the SMF to request the UPF to allocate core network tunnel information for the terminal. In addition, the first message may carry indication information for instructing the SMF to update the access network tunnel information of the terminal. Alternatively, the first message may not carry the indication information, and the first message may carry the access network tunnel information allocated by the second access network device to the terminal, which can be used to instruct the SMF to update the access network tunnel information of the terminal.

[0376] Exemplarily, AMF determines the access network tunnel information allocated by the second access network device to each session of the terminal based on the above-mentioned fifth correspondence, and sends the first message of the terminal based on the access network tunnel information SMF.

[0377] As an example, when the number of sessions of the terminal is greater than or equal to 2, the first message may correspond to at least two sessions of the terminal (for example, all sessions), and the first message carries the identifiers of at least two sessions of the terminal and the access network tunnel information corresponding to the identifier of each session.

[0378] As another example, the first message may also correspond to a session of the terminal. Specifically, the first message carries the identifier of the first session of the terminal and the access network tunnel information corresponding to the first session. The first session is any session of the terminal. If the number of sessions of the terminal is greater than or equal to 2, the AMF may send the first message corresponding to each session of the terminal to the SMF one by one.

[0379] S712, SMF sends the second message of the terminal to UPF.

[0380] Accordingly, the UPF receives the second message.

[0381] In this embodiment of the present application, the second message in step S712 carries the access network tunnel information of the terminal, and does not carry the instruction information requesting the UPF to allocate the core network tunnel information of the terminal. For the description of the second message, please refer to the relevant description in step S406 and will not be described in detail here.

[0382] S713, the second access network device communicates with the UPF based on the core network tunnel information and access network tunnel information of the terminal.

[0383] In an embodiment of the present application, after step S608 or step S613, the second access network device can communicate based on the core network tunnel information and access network tunnel information of the terminal to serve the session of the terminal.

[0384] In an embodiment of the present application, before the terminal switches to the second access network device, the terminal identifier assigned by the second access network device to the terminal and the access network tunnel information respectively assigned to the terminal session will be sent to the AMF, and the core network tunnel information assigned by the UPF to the second access network device serving the terminal will also be sent to the second access network device. Based on this, when the terminal switches to the second access network device (that is, the second access network device receives a switching request message about the terminal), the second access network device does not send a path switching message to the AMF, and does not need to request and wait for the UPF to allocate core network tunnel information to the terminal, thereby improving the signaling storm problem of the NG interface caused by the terminal frequently executing the switching process and improving the switching efficiency. And based on the second switching time information and the fifth corresponding relationship shown in Table 7, the AMF actively updates the N2 information of the terminal and actively sends the first message of the terminal to the SMF to ensure the integrity of the terminal switching process.

[0385] The following, combined with the interaction diagram shown in Figure 8, takes the above-mentioned method 2 where the second access network device allocates a terminal identifier to the terminal and sends it to the AMF in advance, and the access network tunnel information of the terminal served by the second access network device is allocated by the SMF as an example to introduce an application of the communication method provided in an embodiment of the present application. As shown in Figure 8, the method includes the following steps:

[0386] S801: A terminal sends a session establishment request for a first session to a first access network device.

[0387] Correspondingly, the first access network device receives the session establishment request.

[0388] For the description of the first session, please refer to the relevant description in step S701 above.

[0389] S802: The first access network device requests other access network devices to allocate a terminal identifier to the terminal.

[0390] Specifically, the first access network device sends a second request to each of the other access network devices, where the second request is used to request the other access network device to allocate a terminal identifier for the terminal. For example, the second request carries the first identifier of the terminal, which may be the UE ID or C-RNTI of the terminal. Based on the second request, the other access network devices respectively allocate terminal identifiers for the terminal and respectively send a second response to the first access network device, where the second response carries the terminal identifier allocated by the corresponding access network device to the terminal. For example, the second response may carry the first identifier of the terminal and the terminal identifier allocated by the corresponding access network device to the terminal.

[0391] In an embodiment of the present application, the above-mentioned session establishment request can serve as a request trigger condition for the first access network device to request other access network devices to assign a terminal identifier to the terminal, but the request trigger condition of the first request is not limited to this. For details, please refer to the relevant instructions on the request trigger condition of the first request in step S703 above, which will not be described in detail here.

[0392] For the description of other access network devices, please refer to the relevant description in step S403 above, which will not be described in detail here.

[0393] S803: The other access network devices respectively send the terminal identifier allocated to the terminal to the first access network device.

[0394] Correspondingly, the first access network device receives the terminal identifier allocated to the terminal by other access network devices.

[0395] S804, the first access network device sends the terminal identifier allocated to the terminal by other access network devices to the AMF.

[0396] Correspondingly, AMF receives the terminal identifier allocated to the terminal by the other access network device.

[0397] Exemplarily, the AMF stores the terminal identifier assigned to the terminal by other access network devices based on the above-mentioned second response, for example, storing the sixth correspondence shown in Table 8 below.

[0398] Table 8

[0399] S805, request UPF to allocate corresponding core network tunnel information to the terminal.

[0400] As an example, in the above S804, the message sent by the first access network device to the AMF regarding the terminal identifier allocated to the terminal by other access network devices may also include indication information, where the indication information is used to instruct the AMF to request the UPF to allocate corresponding core network tunnel information to the terminals served by the other access network devices through the SMF. As another example, the indication information and the terminal identifier allocated to the terminal by the other access network devices may not be in the same message, and the first access network device may send the indication information to the AMF through another message.

[0401] As another example, the first access network device sends the terminal identifier allocated to the terminal by other access network devices to AMF, triggering AMF to request UPF through SMF to allocate corresponding core network tunnel information to the service terminals of other access network devices.

[0402] Alternatively, in another possible implementation, triggering AMF to request UPF to allocate core network tunnel information through SMF may not depend on whether AMF receives the terminal identifier allocated to the terminal by other access network devices, but may be other triggering conditions, which is not limited in this document.

[0403] For detailed instructions on how AMF requests UPF through SMF to allocate corresponding core network tunnel information to other access network device service terminals, please refer to step S705 above.

[0404] S806, UPF sends the core network tunnel information allocated to the terminal to the corresponding access network device.

[0405] Correspondingly, the access network device receives the core network tunnel information allocated by the UPF to the terminal.

[0406] Specifically, the UPF may send the core network tunnel information corresponding to the service terminals of other access network devices to the first access network device through the AMF and SMF, and the first access network device then sends the core network tunnel information to the other access network devices (including the second access network device) accordingly. For example, the core network tunnel information corresponding to the service terminal of the second access network device is sent to the SMF, the SMF forwards it to the AMF, the AMF forwards it to the first access network device, and the first access network device forwards it to the second access network device. Alternatively, the UPF may also directly send the core network tunnel information to the corresponding access network device through the AMF and SMF, for example, the core network tunnel information of the service terminal of the second access network device is sent to the SMF, the SMF forwards it to the AMF, and the AMF forwards it to the second access network device. For detailed descriptions of how the UPF sends the core network tunnel information allocated to the service terminals of other access network devices to the corresponding access network devices, please refer to step S706 above.

[0407] For example, in the process of the terminal accessing the first access network device and establishing a first session based on the first access network device (or it can also be understood as whenever the terminal establishes a session), the UPF will allocate corresponding core network tunnel information to the newly established session of the terminal serving the second access network device and send it to the second access network device. The second access network device stores the core network tunnel information, so that in step S808, the second access network device can not send a path switching message to the AMF based on the stored core network tunnel information of the terminal.

[0408] Among them, the service granularity of the core network tunnel information can be session granularity, slice granularity, UE-RAN granularity, or RAN granularity, which is not limited in this article.

[0409] S807: The first access network device sends a handover request message corresponding to the terminal to the second access network device based on the first handover time information corresponding to the terminal.

[0410] Correspondingly, the second access network device receives the handover request message.

[0411] Regarding the first switching time information, reference may be made to the relevant description in step S401 above, which will not be described in detail here.

[0412] S808. The second access network device determines not to send a path switching message to the AMF based on the stored core network tunnel information of the terminal.

[0413] As an example, the second access network device may not need to determine whether the second access network device has stored the core network tunnel information of the terminal, but may directly send a corresponding path switching message to the AMF in response to the switching request message.

[0414] S809: AMF determines to switch the terminal to the second access network device based on the second switching time information.

[0415] Exemplarily, the AMF determines, based on the second switching time information, that the identifier of the target access network device of the terminal corresponding to the current time is the identifier of the second access network device; then, based on the identifier of the second access network device and the above-mentioned sixth correspondence stored locally by the AMF, determines the terminal identifier assigned to the terminal by the second access network device, and updates the second identifier of the terminal recorded locally to the terminal identifier assigned to the terminal by the second access network device.

[0416] S810, AMF sends the first message of the terminal to SMF, where the first message carries the identifier of the second access network device.

[0417] Accordingly, the SMF receives the first message.

[0418] In this embodiment of the present application, the first message is used to request the SMF to allocate first access network tunnel information to the terminal based on the identifier of the second access network device, and update the access network tunnel information of the terminal session to the first access network tunnel information. The first access network tunnel information can be access network tunnel information at a session granularity, a slice granularity, a UE-RAN granularity, or a RAN granularity.

[0419] S811, SMF responds to the first message and allocates first access network tunnel information to the terminal.

[0420] Exemplarily, the SMF stores one or more allocable access network tunnel information corresponding to the identifier of the access network device, so that the SMF can allocate the corresponding first access network tunnel information to the terminal based on the identifier of the second access network device carried in the first message.

[0421] As an example, when the access network tunnel information of the terminal is at a session granularity or a slice granularity, the above-mentioned first message may carry the identifiers of one or more sessions of the terminal and the identifier of the second access network device. The first message is used to request the SMF to allocate access network tunnel information to the one or more sessions of the terminal based on the identifier of the second access network device, and update the access network tunnel information of the one or more sessions based on the allocated access network tunnel information. Alternatively, when the access network tunnel information of the terminal is at a session granularity, the first message may also carry the identifier of the terminal. The SMF determines the identifiers of one or more sessions corresponding to the terminal based on the identifier of the terminal, and allocates access network tunnel information to the one or more sessions. In this case, the first access network tunnel information in step S811 includes the access network tunnel information corresponding to the identifiers of the one or more sessions.

[0422] As another example, when the access network tunnel information of the terminal is aggregated access network tunnel information at the UE-RAN granularity or the RAN granularity, the above-mentioned first message may carry the identifier of the terminal and the identifier of the second access network device. The first message is used to request the SMF to allocate aggregated access network tunnel information to the terminal based on the identifier of the second access network device, and update the access network tunnel information of all sessions corresponding to the identifier of the terminal to the aggregated access network tunnel information. Alternatively, the first message may also carry the identifier of one or more sessions of the terminal and the identifier of the second access network device. The update request is used to request the SMF to allocate corresponding aggregated access network tunnel information to the session of the terminal based on the identifier of the second access network device and the identifier of the session. In this case, the first access network tunnel information in step S811 is the aggregated access network tunnel information corresponding to the terminal and the second access network device.

[0423] In some possible implementations, after the SMF allocates access network tunnel information A to the first session of the terminal, the SMF can also store the correspondence between the identifier of the first session, the access network tunnel information A, and the second access network device. When the SMF receives the first message containing the identifier of the session A and the identifier of the second access network device next time, the access network tunnel information of the first session can be directly used with the access network tunnel information A previously allocated to the second access network device to serve the first session.

[0424] S812, SMF sends a second message to UPF.

[0425] For the description of the second message, please refer to the relevant description in S406 above, which will not be described in detail here.

[0426] In some possible implementations, after step S811, the SMF further executes step S813.

[0427] S813, SMF sends the above-mentioned first access network tunnel information to the second access network device.

[0428] In this embodiment of the present application, after the SMF allocates the first access network tunnel information to the second access network device service terminal, the first access network tunnel information can be sent to the second access network device via the AMF. Alternatively, the first access network tunnel information can be sent to the first access network device via the AMF, and the first access network device can send the first access network tunnel information to the second access network device via an inter-satellite link.

[0429] As an example, the first access network tunnel information belongs to the access network tunnel information at the session granularity, and the SMF sends the first access network tunnel information to the second access network device through the AMF, including: the SMF sends the identifiers of one or more sessions and the access network tunnel information corresponding to the one or more sessions to the AMF, and the AMF forwards the identifiers of the one or more sessions and the access network tunnel information corresponding to the one or more sessions to the second access network device.

[0430] It can be understood that SMF sends the identifiers of one or more sessions and the access network tunnel information corresponding to the one or more sessions to the second access network device through AMF, so that when the second access network device subsequently receives a message sent by UPF through access network tunnel information A, it can determine the session corresponding to the message, and the access network tunnel information A corresponds to one of the one or more sessions.

[0431] As another example, the first access network tunnel information belongs to the aggregated access network tunnel information, and SMF sends the first access network tunnel information to the second access network device through AMF, including: SMF sends the first access network tunnel information and the identifier of the second access network device to AMF, and AMF forwards the first access network tunnel information to the second access network device.

[0432] Alternatively, in some possible implementations, the communication method provided in the present application includes the above steps S801-S812, and S814, wherein S814 is performed after step S812.

[0433] S814, UPF sends the above-mentioned first access network tunnel information to the second access network device.

[0434] Exemplarily, the UPF sending the above-mentioned first access network tunnel information to the second access network device includes: the UPF sending one or more session identifiers and the access network tunnel information corresponding to each session to the second access network device.

[0435] S815, the second access network device communicates with the UPF based on the core network tunnel information of the terminal and the first access network tunnel information.

[0436] For example, a GTP-U tunnel is established between the second access network device and the UPF for communication based on the core network tunnel information of the terminal and the above-mentioned first access network tunnel information.

[0437] In an embodiment of the present application, before the terminal switches to the second access network device, the terminal identifier assigned by the second access network device to the terminal will be sent to the AMF, and the core network tunnel information assigned by the UPF to the second access network device serving the terminal will also be sent to the second access network device. Based on this, when the terminal switches to the second access network device (that is, the second access network device receives a switching request message about the terminal), the second access network device does not send a path switching message to the AMF, that is, the second access network device does not need to request and wait for the UPF to allocate core network tunnel information for the terminal, thereby improving switching efficiency. In addition, the SMF allocates access network tunnel information to the second access network device serving the terminal, and the second access network device does not need to send access network tunnel information to the AMF, thereby reducing signaling interaction and further improving switching efficiency. In addition, there is no need to request other access network devices (including the second access network device) through the first access network device to obtain the access network tunnel information allocated to the terminal, thereby reducing the signaling interaction of the Xn interface between the first access network device and the second access network device, further reducing performance loss, and improving switching efficiency.

[0438] In conjunction with Figure 9, the following describes an application of the communication method provided in an embodiment of the present application, in which the second access network device allocates access network tunnel information to the terminal, the type of tunnel information (access network tunnel information and core network tunnel information) is UE-RAN granularity or RAN granularity, the second access network device allocates access network tunnel information to the terminal and sends it to the AMF through the above-mentioned method 1, and the AMF sends the second service time information to the SMF, so that the SMF can actively trigger the execution of the relevant process of switching the terminal to the second access network device, and further omits the switching request message sent by the AMF to the SMF through the N11 interface in the switching process. As shown in Figure 9, the method includes the following steps:

[0439] S901: AMF obtains second switching time information corresponding to the terminal.

[0440] S902, AMF sends second switching time information to the first access network device.

[0441] Correspondingly, the first access network device receives the second switching time information sent by the AMF.

[0442] S903: The first access network device determines first switching time information based on the second switching time information.

[0443] For the description of S901-S903, please refer to the relevant description of S601-S603 above, which will not be described in detail here.

[0444] S904, AMF sends the second switching time information to SMF.

[0445] Correspondingly, the SMF receives the second switching time information.

[0446] In the embodiment of the present application, S902 and S904 can be executed simultaneously or sequentially, and the order is not limited.

[0447] S905: The first access network device sends a handover request message corresponding to the terminal to the second access network device based on the first handover time information corresponding to the terminal.

[0448] Correspondingly, the second access network device receives the handover request message.

[0449] S906: The second access network device determines whether the core network tunnel information of the terminal has been stored.

[0450] The core network tunnel information may be at a UE-RAN granularity or a RAN granularity.

[0451] In the embodiment of the present application, when the second access network device determines that the core network tunnel information of the terminal is not stored, the second access network device executes step S907; when the second access network device determines that the core network tunnel information of the terminal is stored, the second access network device executes step S910.

[0452] S907, the second access network device sends a path switching message to the AMF.

[0453] Correspondingly, AMF requests UPF to allocate the core network tunnel information of the terminal based on the path switching message.

[0454] For details, please refer to the relevant instructions in step S606 above, which will not be described in detail here.

[0455] S908: Send the core network tunnel information of the terminal allocated by the UPF to the second access network device.

[0456] For details, please refer to the relevant instructions in step S607 above, which will not be described in detail here.

[0457] S909, the access network tunnel information of the terminal allocated by the second access network device is sent to SMF and UPF through AMF.

[0458] For details, please refer to the relevant instructions in step S608 above, which will not be described in detail here.

[0459] S910. The second access network device determines not to send a path switching message to the AMF based on the core network tunnel information of the terminal stored therein.

[0460] In an embodiment of the present application, when the second access network device determines that a terminal identifier and an aggregated access network tunnel have been assigned to the terminal, it does not send a path switching message to the AMF, thereby improving the signaling storm problem of the NG interface caused by the terminal frequently executing the switching process and improving the switching efficiency.

[0461] S911, AMF determines to switch the terminal to the second access network device based on the second switching time information, and determines not to send the first message to SMF.

[0462] In this embodiment of the present application, after determining to switch the terminal to the second access network device, the AMF determines not to send the first message to the SMF based on the second service time information of the terminal having been sent to the SMF in step S904. This improves the signaling storm problem of the N11 interface in the terminal switching process, further reduces performance loss, and improves switching efficiency.

[0463] Regarding how to avoid the AMF executing both step S911 and steps S907-S909 based on the path switching message sent by the second access network device, resulting in an unknown program error, please refer to the relevant description in step S611 above.

[0464] S912: The SMF determines to switch the terminal to the second access network device based on the second switching time information.

[0465] As an example, if the SMF stores the third correspondence shown in Table 4 or Table 5 above, then 'SMF determines to switch the terminal to the second access network device based on the second switching time information', it may specifically include: SMF determines that the identifier of the terminal's current target access network device is the identifier of the second access network device based on the second switching time information (refer to Table 1), and determines the aggregated access network tunnel information corresponding to the identifier of the terminal and the identifier of the second access network device based on the locally stored third correspondence; based on the aggregated access network tunnel information, SMF updates the access network tunnel information corresponding to each session of the terminal in the local configuration to the aggregated access network tunnel information allocated to the terminal by the second access network device.

[0466] As another example, if the fourth correspondence shown in Table 6 above is stored in the SMF, then 'SMF determines to switch the terminal to the second access network device based on the second switching time information', which may specifically include: SMF determines that the identifier of the terminal's current target access network device is the identifier of the second access network device based on the second switching time information (refer to Table 1), and determines the aggregated access network tunnel information corresponding to the session of the terminal and the identifier of the second access network device based on the locally stored fourth correspondence, and updates the access network tunnel information of the terminal's session based on the aggregated access network tunnel information.

[0467] S913, SMF sends a second message to UPF.

[0468] In the embodiment of the present application, after the SMF determines to switch the terminal to the second access network device based on the second switching time information, it sends a second message to the UPF. For an explanation of the second message, please refer to the relevant description in step S406 and will not be described in detail here.

[0469] In an embodiment of the present application, AMF sends the second service time information to SMF, and SMF can actively trigger the execution of related processes related to the terminal switching to the second access network device, further omitting the switching request message sent by AMF to SMF through the N11 interface in the switching process, further alleviating the communication pressure of the N11 interface and improving the switching efficiency.

[0470] S914, the second access network device communicates with the UPF based on the core network tunnel information and access network tunnel information of the terminal.

[0471] In conjunction with the interaction diagram shown in FIG10, the following describes an application of the communication method provided in an embodiment of the present application, taking the above-mentioned method 2 and the combination of method 2 as examples, in which the terminal identifier and access network tunnel information allocated by the second access network device to the terminal are sent in advance to the AMF, and the type of the access network tunnel information is access network tunnel information with session granularity, and the AMF sends the service time of the second access network device serving the terminal and the access network tunnel information allocated by the second access network device to the terminal in advance to the SMF, so that the SMF can actively trigger the execution of the relevant process of the terminal switching to the second access network device. As shown in FIG10, the communication method provided in an embodiment of the present application includes the following steps:

[0472] S1001: A terminal sends a session establishment request to a first access network device.

[0473] Correspondingly, the first access network device receives the session establishment request.

[0474] S1002: The first access network device requests other access network devices to allocate access network tunnel information and a terminal identifier to the terminal.

[0475] S1003: The first access network device receives access network tunnel information and a terminal identifier allocated to the terminal by other access network devices.

[0476] S1004, the first access network device sends the first information to the AMF, where the first information includes the access network tunnel information and terminal identifier allocated to the terminal by other access network devices.

[0477] Accordingly, the AMF receives the first information.

[0478] S1005, request UPF to allocate core network tunnel information to the terminal.

[0479] S1006, UPF sends the core network tunnel information allocated to the terminal to the corresponding access network device.

[0480] S1007: AMF obtains the second switching time information corresponding to the terminal.

[0481] For detailed description of steps S1001-S1007, please refer to the relevant description of steps S701-S707 above.

[0482] S1008, AMF sends the second information to SMF based on the second switching time information and the access network tunnel information and terminal identifier allocated to the terminal by other access network devices.

[0483] Correspondingly, the SMF receives the second information, which includes the service time of the second access network device serving the terminal and the access network tunnel information allocated by the second access network device to the terminal.

[0484] As an example, the second information includes the second switching time information corresponding to the terminal and the access network tunnel information allocated to the terminal by the other access network devices. For example, the second information includes other data in Table 1 and Table 7 except the terminal identifier. It should be noted that the identifier of the terminal session in the second information sent by AMF to SMF can be a PDU session ID or an SM context ID, wherein the PDU session ID can be understood as the public identifier of the session, and the SM context ID is a private identifier allocated by SMF to the session for identifying the session between SMF and AMF.

[0485] For example, AMF can determine that the identifier of UE1's target access network device is RAN2 ID based on Table 1, and based on the PDU session ID1 of the session corresponding to UE1, the RAN2 ID, and Table 7 above, determine the access network tunnel information corresponding to the PDU session ID1 and the RAN2 ID as the access network tunnel information of the session.

[0486] As another example, the second information includes a correspondence between an identifier of each session of the terminal, a service time during which the access network device serves the terminal, and access network tunnel information corresponding to the service time. The session identifier may be a PDU session ID or an SM context ID for the session. The following describes the data included in the second information using the PDU session ID as an example, in conjunction with Table 9.

[0487] For example, as shown in Table 9 below, PDU session ID1 and PDU session ID2 correspond to two different sessions of the terminal respectively. The session corresponding to PDU session ID1 is in the two time periods of 00:00-00:05 and 05:00-05:05 (for example, the terminal is switched to the first access network device in these two time periods), and the tunnel information AN tunnel info1 is used (for example, the access network tunnel information allocated by the first access network device to the PDU session ID1 of the terminal is AN tunnel info1); the session corresponding to PDU session ID2 is in the two time periods of 00:00-00:05 and 05:00-05:05 (for example, the terminal is switched to the second access network device in these two time periods), and the tunnel information AN tunnel info2 is used (for example, the access network tunnel information allocated by the first access network device to the PDU session ID2 of the terminal is AN tunnel info2).

[0488] Table 9 does not actually include the data content indicated in brackets. The access network device identifier indicated in brackets in the service time column of Table 9 is only for the convenience of indicating which access network device the terminal accesses. For example, '00:00-00:05, 05:00-05:05 (RAN1)' means that the service time for the terminal to switch to RAN1 is 00:00-00:05 and 05:00-05:05.

[0489] Table 9

[0490] S1009: The first access network device sends a handover request message corresponding to the terminal to the second access network device based on the first handover time information corresponding to the terminal.

[0491] Correspondingly, the second access network device receives the handover request message.

[0492] S1010. The second access network device determines not to send a path switching message to the AMF based on the access network tunnel information and terminal identifier allocated to the terminal.

[0493] S1011: AMF determines to switch the terminal to the second access network device based on the second switching time information.

[0494] For detailed descriptions of steps S1009-S1011, please refer to the relevant descriptions of steps S708-S710 above.

[0495] In an embodiment of the present application, after determining to switch the terminal to the second access network device, AMF determines not to send the first message to SMF based on the fact that AMF has sent the access network tunnel information allocated to the terminal by other access network devices to SMF in step S1007, and has sent the second service time information of the terminal to SMF in step S1010.

[0496] S1012: Based on the second information, the SMF updates the access network tunnel information of the terminal's session to the access network tunnel information allocated by the second access network device to the terminal's session.

[0497] As an example, the second information includes other data in Table 1 and Table 7 except the terminal identifier. Based on the second information, SMF updates the access network tunnel information of the terminal's session to the access network tunnel information allocated by the second access network device to the terminal's session, specifically including: SMF determines that the identifier of the target access network device of the terminal corresponding to the current time is the identifier of the second access network device based on Table 1, and based on the other data in Table 7 except the terminal identifier, determines the access network tunnel information A corresponding to the identifier of the second access network device and the first session of the terminal, and updates the access network tunnel information corresponding to the first session to the access network tunnel information A.

[0498] For example, in Table 1, the identifier of the target access network device corresponding to the current time is RAN2 ID (second access network device), the identifier of the first session of the terminal is PDU session ID1, and the access network tunnel information corresponding to the PDU session ID1 and the RAN2 ID is AN tunnel info3. Based on this, the access network tunnel information corresponding to one or more sessions of the terminal is updated to the access network tunnel information allocated by the second access network device to the corresponding session.

[0499] Alternatively, as another example, the second information includes data as shown in Table 9 above. Based on the second information, the SMF updates the access network tunnel information of the terminal's session to the access network tunnel information allocated by the second access network device to the terminal's session, specifically including: the SMF determines the service time corresponding to the current moment based on Table 9, and updates the access network tunnel information of the session (one or more) corresponding to the service time to the access network tunnel information corresponding to the session and the service time. For example, the service time corresponding to the current moment is 00:00-00:05, and the terminal's session includes PDU session ID1 and PDU session ID2. The SMF updates the access network tunnel information of the session corresponding to PDU session ID1 to AN tunnel info1 corresponding to the time of 00:00-00:05, and updates the access network tunnel information of the session corresponding to PDU session ID2 to AN tunnel info2 corresponding to the time of 00:00-00:05.

[0500] S1013, SMF sends a second message to UPF, where the second message is used to request that the access network tunnel information corresponding to one or more sessions of the terminal be updated to the access network tunnel information allocated by the second access network device to the corresponding session.

[0501] In the embodiment of the present application, after the SMF determines to switch the terminal to the second access network device based on the second information, it sends a second message to the UPF. For an explanation of the second message, please refer to the relevant description in step S406 and will not be described in detail here.

[0502] S1014, the second access network device and the UPF communicate based on the core network tunnel information and access network tunnel information of the terminal. For example, the second access network device and the UPF establish a GTP-U tunnel based on the core network tunnel information and access network tunnel information of the terminal for communication.

[0503] In some other possible implementations, the method provided in the embodiment of the present application may also include steps S1001-S1012, S1015-S1016, and S1014.

[0504] S1015, SMF sends the above-mentioned second information to UPF.

[0505] Correspondingly, the UPF receives the second information, which includes the service time of the terminal accessing the second access network device and the access network tunnel information allocated by the second access network device to the terminal.

[0506] For the description of the second information, please refer to the relevant description in step S1012 above. It should be noted that, in the second information sent by the SMF to the UPF, the session identifier can be the PDU session ID or N4 session ID of the session.

[0507] S1016, UPF updates the access network tunnel information of the terminal session based on the second information.

[0508] Specifically, the UPF updates the access network tunnel information of the session whose service time corresponds to the current time based on the second information, and performs step S1014 after step S1016. Regarding how the UPF determines the access network tunnel information corresponding to one or more sessions of the terminal corresponding to the current time based on the second information, reference may be made to the relevant description of the SMF determining the access network tunnel information corresponding to one or more sessions of the terminal corresponding to the current time based on the second information in step S1012 above.

[0509] Based on this, UPF actively triggers the execution of related processes for updating the access network tunnel information of the terminal session based on the service time through the second information. There is no need for SMF to send an N4 session update request to UPF, which further reduces the signaling interaction of the N4 interface in the terminal switching process, reduces performance loss, and improves switching efficiency.

[0510] The following, in conjunction with the interaction diagram shown in Figure 8, uses the above-mentioned method 2 to allocate a terminal identifier to the terminal through the second access network device and send it to the AMF in advance, the access network tunnel information of the second access network device serving the terminal is allocated by the SMF, and the AMF sends the second service time information to the SMF, so that the SMF can actively trigger the execution of the relevant processes related to the terminal switching to the second access network device and as an example to introduce an application of the communication method provided in the embodiment of the present application. As shown in Figure 11, the communication method provided in the embodiment of the present application includes the following steps:

[0511] S1101: A terminal sends a session establishment request to a first access network device.

[0512] Correspondingly, the first access network device receives the session establishment request.

[0513] S1102: The first access network device requests other access network devices to allocate a terminal identifier to the terminal.

[0514] S1103: The first access network device receives a terminal identifier allocated to the terminal by other access network devices.

[0515] S1104, the first access network device sends the terminal identifier allocated to the terminal by other access network devices to the AMF.

[0516] S1105, request UPF to allocate core network tunnel information to the terminal.

[0517] S1106, UPF sends the core network tunnel information allocated to the terminal to the corresponding access network device.

[0518] For a detailed description of steps S1101-S1104, please refer to the above description of steps S801-S806.

[0519] S1107, AMF obtains the second switching time information corresponding to the terminal.

[0520] For detailed description of how to obtain the second switching time information, please refer to steps S601 to S604 in FIG6 or the related descriptions in steps S401 and S404 in FIG4 , which will not be described in detail here.

[0521] S1108, AMF sends the second switching time information to SMF.

[0522] Correspondingly, the SMF receives the second switching time information sent by the AMF.

[0523] S1109, SMF allocates corresponding access network tunnel information to multiple access network device service terminals based on the second switching time information.

[0524] In an embodiment of the present application, the multiple access network devices include the access network device corresponding to the identifier of the access network device included in the second switching time information. Optionally, the access network tunnel information allocated by the SMF to the terminal may be access network tunnel information at a session granularity, a UE-RAN granularity, or a RAN granularity, which is not limited in this document.

[0525] Exemplarily, the access network tunnel information allocated by the SMF to the terminal belongs to the access network tunnel information of the session granularity. The SMF can allocate the access network tunnel information corresponding to the identifier of the access network device and the identifier of the terminal session based on the second switching time information shown in Table 1 above, and obtain and store the seventh correspondence between the data other than the terminal identifier in Table 7 above, or obtain and store the second information shown in Table 9 above. It should be noted that the identifier of the session in the seventh correspondence and the second information stored in the SMF can be either a PDU session ID or an SM context ID.

[0526] In one possible implementation, after the SMF allocates corresponding access network tunnel information to multiple access network device service terminals, the SMF may send the access network tunnel information allocated by the SMF to the corresponding access network devices through the AMF. Alternatively, the SMF may first send the access network tunnel information allocated to the multiple access network device service terminals to the first access network device, and then the first access network device sends the access network tunnel information allocated by the SMF to the corresponding access network device service terminal through the inter-satellite link.

[0527] S1110: The first access network device determines to switch the terminal to the second access network device based on the first switching time information corresponding to the terminal, and sends a switching request message corresponding to the terminal to the second access network device.

[0528] Correspondingly, the second access network device receives the handover request message.

[0529] S1111, the second access network device determines not to send a path switching message to the AMF based on the terminal identifier having been allocated to the terminal.

[0530] S1112: The AMF determines to switch the terminal to the second access network device based on the second switching time information.

[0531] For a detailed description of steps S1110-S1112, please refer to the relevant descriptions of steps S807-S809 above.

[0532] S1113, the SMF determines to update the access network tunnel information corresponding to one or more sessions of the terminal based on the second switching time information.

[0533] Exemplarily, the access network tunnel information allocated by the SMF to the terminal belongs to the access network tunnel information at the session granularity. The SMF can determine, based on the second switching time information (see Table 1), that the identifier of the terminal's current target access network device is the identifier of the second access network device; and based on the seventh corresponding relationship stored locally, determine the first access network tunnel information corresponding to the identifier of the first session of the terminal and the identifier of the second access network device; the SMF updates the locally stored access network tunnel information corresponding to the first session to the first access network tunnel information. Alternatively, the SMF can also update the access network tunnel information corresponding to one or more sessions of the terminal based on the second information shown in Table 9 above.

[0534] S1114, SMF sends a second message to UPF.

[0535] For the description of the second message, please refer to the relevant description in S406 above, which will not be described in detail here.

[0536] S1115, the second access network device communicates with the UPF based on the core network tunnel information and access network tunnel information of the terminal.

[0537] In some other possible implementations, the communication method provided in the present application may also include S1101-S1113, S1116-S1117, and S1115.

[0538] S1116, SMF sends third information to UPF, where the third information includes the service time and access network tunnel information corresponding to the identifier of the terminal session.

[0539] Accordingly, the UPF receives the third information.

[0540] Exemplarily, the third information may include the same data as the second information shown in Table 9 above. It should be noted that the session identifier in the third information sent by the SMF to the UPF may be the PDU session ID or N4 session ID of the session.

[0541] S1117, UPF updates the access network tunnel information of the terminal session based on the third information.

[0542] Specifically, based on the second information, the UPF updates the access network tunnel information for the session whose service time corresponds to the current time, and executes step S1115 after step S1117. For example, the UPF determines the service time corresponding to the current moment and updates the access network tunnel information for the session(s) corresponding to the service time to the access network tunnel information corresponding to the session and the service time. For details, please refer to the description of the SMF updating the access network tunnel information of the terminal session based on Table 9 in step S1013 above.

[0543] In one possible implementation, after the SMF allocates corresponding access network tunnel information to multiple access network device service terminals in step S1109, the access network tunnel information allocated by the SMF to the access network device service terminal may not be sent to the corresponding access network device through the AMF. Instead, the UPF sends the access network tunnel information allocated by the SMF to the access network device service terminal to the corresponding access network device after step S1114 or after step S1117.

[0544] In addition, the present application also provides a communication device, including a unit for executing any one of the communication methods in Figures 4 to 11.

[0545] The present application also provides a communication device, including a processor, wherein the processor is configured to execute any one of the communication methods shown in FIG. 4 to FIG. 11 .

[0546] The present application also provides a communication system, including an access and mobility management function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 4, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 4, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 4.

[0547] The present application also provides a communication system, including an access and mobility management function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 6, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 6, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 6.

[0548] The present application also provides a communication system, including an access and mobility management function network element, a session management function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 7, the session management function network element is used to execute the steps executed by the session management function network element in any one of the communication methods in Figure 7, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 7, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 7.

[0549] The present application also provides a communication system, including an access and mobility management function network element, a session management function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 8, the session management function network element is used to execute the steps executed by the session management function network element in any one of the communication methods in Figure 8, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 8, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 8.

[0550] The present application also provides a communication system, including an access and mobility management function network element, a session management function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 9, the session management function network element is used to execute the steps executed by the session management function network element in any one of the communication methods in Figure 9, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 9, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 9.

[0551] The present application also provides a communication system, including an access and mobility management function network element, a session management function network element, a user plane function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 10, the session management function network element is used to execute the steps executed by the session management function network element in any one of the communication methods in Figure 10, the user plane function network element is used to execute the steps executed by the user plane function network element in any one of the communication methods in Figure 10, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 10, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 7.

[0552] The present application also provides a communication system, including an access and mobility management function network element, a session management function network element, a user plane function network element, a first access network device, and a second access network device, wherein the access and mobility management function network element is used to execute the steps executed by the access and mobility management function network element in any one of the communication methods in Figure 11, the session management function network element is used to execute the steps executed by the session management function network element in any one of the communication methods in Figure 11, the user plane function network element is used to execute the steps executed by the user plane function network element in any one of the communication methods in Figure 11, the first access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 11, and the second access network device is used to execute the steps executed by the first access network device in any one of the communication methods in Figure 11.

[0553] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways.

[0554] The present application also provides a computer program for implementing the operations and / or processing performed by the AMF shown in Figures 4-11 in the communication method provided in the present application.

[0555] The present application also provides a computer program, which is used to implement the operations and / or processing performed by the SMF shown in Figures 4 to 11 in the communication method provided by the present application.

[0556] The present application also provides a computer program for implementing the operations and / or processing performed by the UPF shown in Figures 4-11 in the communication method provided by the present application.

[0557] The present application also provides a computer program, which is used to implement the operations and / or processing performed by the first access network device or the second access network device shown in Figures 4-11 in the communication method provided by the present application.

[0558] The present application also provides a computer-readable storage medium, which stores computer code. When the computer code runs on a computer, the computer executes the operations and / or processing performed by the AMF shown in Figures 4-11 in the communication method provided by the present application.

[0559] The present application also provides a computer-readable storage medium, which stores computer code. When the computer code runs on a computer, it enables the computer to execute the operations and / or processing performed by the SMF shown in Figures 4-11 in the communication method provided by the present application.

[0560] The present application also provides a computer-readable storage medium, which stores computer code. When the computer code runs on a computer, it enables the computer to execute the operations and / or processing performed by the UPF shown in Figures 4-11 in the communication method provided by the present application.

[0561] The present application also provides a computer-readable storage medium, which stores computer code. When the computer code runs on a computer, the computer executes the operations and / or processing performed by the first access network device or the second access network device shown in Figures 4-11 in the communication method provided by the present application.

[0562] The present application also provides a computer program product, which includes a computer code or a computer program. When the computer code or computer program is run on a computer, the operations and / or processing performed by the AMF shown in Figures 4-11 in the communication method provided by the present application are executed.

[0563] The present application also provides a computer program product, which includes computer code or computer program. When the computer code or computer program runs on a computer, the operations and / or processing performed by the SMF shown in Figures 4-11 in the communication method provided by the present application are executed.

[0564] The present application also provides a computer program product, which includes computer code or computer program. When the computer code or computer program runs on a computer, the operations and / or processing performed by the UPF shown in Figures 4-11 in the communication method provided by the present application are executed.

[0565] The present application also provides a computer program product, which includes computer code or computer program. When the computer code or computer program runs on a computer, the operations and / or processing performed by the first access network device or the second access network device shown in Figures 4-11 in the communication method provided by the present application are executed.

[0566] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: Applied to a second access network device, the method comprises: Receiving a handover request message from the first access network device, where the handover request message is used to request handover of the terminal to the second access network device; Communicate with the user plane function network element based on the switching request message and the core network tunnel information of the terminal stored in the second access network device.

2. The method according to claim 1, characterized in that Before receiving the handover request message from the first access network device, the method further includes: Receive core network tunnel information of the terminal, and store the core network tunnel information.

3. The method according to claim 1, characterized in that Before receiving the switching request message from the first access network device, the method further includes: receiving core network tunnel information of the terminal, and storing the core network tunnel information.

4. The method according to claim 3, characterized in that: The receiving core network tunnel information of the terminal includes: receiving core network tunnel information of the terminal from the first access network device, where the core network tunnel information of the terminal is core network tunnel information that the first access network device requests the user plane function network element to allocate to the terminal, where the core network tunnel information is used to establish a tunnel between the second access network device and the user plane function network element, where the tunnel is used to carry data of the terminal; Alternatively, the receiving of the core network tunnel information of the terminal includes: receiving the core network tunnel information of the terminal from the session management function network element, the core network tunnel information of the terminal being allocated by the user plane function network element for establishing a tunnel for the terminal between the second access network device and the user plane function network element when the terminal previously accessed the second access network device.

5. The method according to claim 1 or 2, characterized in that: After receiving the handover request message from the first access network device, the method further includes: If the second access network device does not store the core network tunnel information of the terminal, or the second access network device does not allocate access network tunnel information to the terminal, a path switching message is sent to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

6. The method according to claim 1 or 2, characterized in that: After receiving the handover request message from the first access network device, the method further includes: If the second access network device has stored the core network tunnel information of the terminal and the second access network device has allocated the access network tunnel information to the terminal, a path switching message is not sent to the access and mobility management function network element, and the path switching message is used to switch the path corresponding to the terminal.

7. The method according to any one of claims 1 to 6, characterized in that The method further comprises: Allocating the access network tunnel information to the terminal; The access network tunnel information is sent to an access and mobility management function network element.

8. The method according to claim 1 or 2, characterized in that: Before receiving the handover request message from the first access network device, the method further includes: receiving a first request, where the first request is used to request allocation of access network tunnel information for the terminal; Allocating access network tunnel information to the terminal based on the first request; A first response is sent, where the first response carries the access network tunnel information.

9. The method according to claim 8, characterized in that The first response also carries an identifier of the second access network device.

10. The method according to claim 8 or 9, characterized in that: The first request includes identification information of a first session of the terminal, and the first request is specifically used to request allocation of access network tunnel information for the first session.

11. The method according to any one of claims 8 to 10, characterized in that: The first request comes from the first access network device, and the sending of the first response includes: The first response is sent to the first access network device, where the first response includes the access network tunnel information and first indication information, and the first indication information is used to instruct the first access network device to send the access network tunnel information to the access and mobility management function network element.

12. The method according to any one of claims 8 to 10, characterized in that: The first request comes from the access and mobility management function network element, and the sending the first response includes: sending the first response to the access and mobility management function network element.

13. The method according to claim 10, characterized in that The core network tunnel information corresponds to the first session of the terminal.

14. The method according to claim 1 or 2, characterized in that: Before receiving the handover request message from the first access network device, the method further includes: receiving a second request from the first access network device, where the second request is used to request the second access network device to allocate a terminal identifier to the terminal; Based on the second request, a terminal identifier is allocated to the terminal; and a second response is sent to the first access network device, where the second response carries the terminal identifier.

15. The method according to claim 14, characterized in that The second response also carries second indication information, where the second indication information is used to instruct the first access network device to send the terminal identifier to the access and mobility management function network element.

16. The method according to any one of claims 1 to 15, characterized in that The terminal is a stationary terminal.

17. The method according to claim 1 or 2, characterized in that: After receiving the handover request message from the first access network device, the method further includes: Receive first access network tunnel information from a session management network element, where the first access network tunnel information is allocated by the session management network element for the tunnel between the second access network device and the UPF to establish the terminal.

18. A communication method, characterized in that: Applied to a first access network device, the method includes: Determine, based on first switching time information of the terminal, to switch the terminal to a second access network device, where the first switching time information includes a time when at least one access network device serves the terminal, and the at least one access network device includes the second access network device; A switching request message is sent to the second access network device, where the switching request message is used to request that the terminal be switched to the second access network device.

19. The method according to claim 18, characterized in that The method further comprises: determining the first switching time information based on the access time of the terminal to the at least one access network device in the satellite operation cycle; or, determining the first switching time information based on the location and ephemeris information of the terminal; or, The first switching time information is received from an access and mobility management function network element.

20. The method according to claim 18 or 19, characterized in that The satellite corresponding to the at least one access network device and the satellite corresponding to the first access network device belong to the same constellation; or, A satellite corresponding to the at least one access network device has a direct and / or indirect inter-satellite link connection with a satellite corresponding to the first access network device; or, The coverage area of ​​each of the at least one access network device includes the location of the terminal.

21. The method according to any one of claims 18 to 20, characterized in that Before sending the switching request message to the second access network device, the method further includes: Requesting the second access network device to allocate access network tunnel information to the terminal; Receiving the access network tunnel information from the second access network device; The access network tunnel information is sent to an access and mobility management function network element.

22. The method according to claim 21, characterized in that The requesting the second access network device to allocate access network tunnel information to the terminal comprises: Request the second access network device to allocate access network tunnel information for the first session of the terminal.

23. The method according to claim 21, characterized in that The requesting the second access network device to allocate access network tunnel information for the first session of the terminal includes: During the process of the terminal establishing the first session through the first access network device, the terminal requests the second access network device to allocate access network tunnel information for the first session.

24. The method according to any one of claims 18 to 20, characterized in that Before sending the switching request message to the second access network device, the method further includes: Request other access network devices to allocate a terminal identifier for the terminal, the other access network devices including one or more access network devices other than the first access network device among the at least one access network device; receive the terminal identifier allocated to the terminal by the other access network devices; and send the terminal identifier allocated to the terminal by the other access network devices to the access and mobility management function network element.

25. The method according to claim 24, characterized in that The requesting the at least one access network device to allocate a terminal identifier for the terminal includes: during the process of establishing a first session by the terminal through the first access network device, requesting the at least one access network device to allocate a terminal identifier for the terminal.

26. The method according to any one of claims 18 to 20, characterized in that Before sending the switching request message to the second access network device, the method further includes: Requesting the user plane function network element to allocate core network tunnel information for the terminal; Receiving first core network tunnel information from the user plane function network element, where the first core network tunnel information corresponds to the second access network device; Send the first core network tunnel information to the second access network device.

27. The method according to any one of claims 18 to 26, characterized in that The terminal is a stationary terminal.

28. The method according to claim 19, characterized in that Before determining to switch the terminal to the second access network device based on the first switching time information of the terminal, the method further includes: The first access network device determines whether the terminal is a stationary terminal, and determines to switch the terminal to the second access network device based on the first switching time information of the terminal.

29. The method according to claim 28, characterized in that When determining that the terminal is a stationary terminal, the first access network device obtains (or determines) first switching time information.

30. A communication method, characterized in that: The method is applied to an access and mobility management function network element, and the method comprises: Determine, based on second switching time information of the terminal, to switch the terminal from the first access network device to the second access network device, where the second switching time information includes a time when at least one access network device serves the terminal, and the at least one access network device includes the second access network device; A first message is sent to a session management function network element, where the first message is used to update access network tunnel information of the terminal.

31. The method according to claim 30, characterized in that The first message includes one or more of the following: Access network tunnel information allocated by the second access network device to the terminal; An identifier of the second access network device; The identifier of the first session of the terminal.

32. The method according to claim 31, characterized in that When the first message includes the identifier of the first session, the first message is specifically used to update the access network tunnel information of the first session.

33. The method according to any one of claims 30 to 32, characterized in that: The method further comprises: The access and mobility management function network element determines the second switching time information based on the access time of the terminal accessing the at least one access network device in the satellite operation cycle; or, The access and mobility management function network element determines the second switching time information based on the location and ephemeris information of the terminal.

34. The method according to any one of claims 30 to 33, characterized in that: The method further comprises: Receive the access network tunnel information allocated by the second access network device to the terminal; and send the access network tunnel information allocated by the second access network device to the terminal to the session management function network element.

35. The method according to claim 34, characterized in that The access network tunnel information includes aggregated access network tunnel information.

36. The method according to any one of claims 30 to 35, characterized in that Before determining to switch the terminal from the first access network device to the second access network device based on the second switching time information of the terminal, the method further includes: Receive access network tunnel information allocated by the second access network device to the terminal.

37. The method according to any one of claims 30 to 36, characterized in that The coverage of the at least one access network device includes the location of the terminal.

38. The method according to any one of claims 30 to 37, characterized in that The terminal is a stationary terminal.

39. The method according to any one of claims 30 to 38, characterized in that The determining, based on the second switching time information of the terminal, to switch the terminal to the second access network device specifically includes: In the case that the terminal is a stationary terminal, it is determined to switch the terminal to the second access network device based on the second switching time information of the terminal.

40. A communication method, characterized in that: Applied to a session management function network element, the method comprises: receiving a first message from an access and mobility management function network element, where the first message is used to update access network tunnel information of the terminal, and the first message includes an identifier of a second access network device; Allocating access network tunnel information to the terminal based on the identifier of the second access network device; The allocated access network tunnel information is sent to a user plane function network element, where the allocated access network tunnel information is used by the user plane function network element to update the access network tunnel information of the terminal.

41. The method according to claim 40, characterized in that The method further comprises: Send the core network tunnel information of the terminal to the second access network device.

42. The method according to claim 40 or 41, characterized in that The method further comprises: Send the allocated access network tunnel information to the second access network device.

43. A communication method, characterized in that: Applied to a session management function network element, the method comprises: receiving access network tunnel information allocated to the terminal by the second access network device from the access and mobility management function network element; receiving a first message from the access and mobility management function network element, where the first message is used to update the access network tunnel information of the terminal, and the first message includes an identifier of the second access network device; Based on the identifier of the second access network device, the access network tunnel information allocated by the second access network device to the terminal is sent to the user plane function network element, and the access network tunnel information is used by the user plane function network element to update the access network tunnel information of the terminal.

44. The method according to claim 43, before receiving the first message from the access and mobility management function network element, further comprising: Send the core network tunnel information of the terminal to the second access network device.

45. A communication system, characterized in that: The system includes a first access network device, a second access network device, and an access and mobility management function network element; Wherein, the second access network device is used to perform the method according to any one of claims 1 to 17; The first access network device is used to perform the method according to any one of claims 18 to 29; The access and mobility management function network element is used to execute the method as described in any one of claims 30-39.

46. ​​The system according to claim 45, characterized in that The system also includes a session management function network element; The session management function network element is used to execute the method according to any one of claims 40 to 42; or, The session management function network element is used to execute the method as claimed in claim 43 or 44.

47. A communication method, applied to a session management function network element, the method comprising: Receiving second switching time information from an access and mobility management function network element, where the second switching time information includes access time of at least one access network device corresponding to the terminal; Based on the second switching time information, determine to switch the terminal to a second access network device; Request the user plane function network element to update the access network tunnel information of the terminal to the access network tunnel information of the second access network device serving the terminal.

48. The method according to claim 47, characterized in that Before determining to switch the terminal to the second access network device based on the second switching time information, the method further includes: Receive access network tunnel information allocated to the terminal by other access network devices from the access and mobility management function network element, wherein the other access network devices include one or more access network devices among the at least one access network device except the first access network device.

49. The method according to claim 47 or 48, characterized in that The access network tunnel information of the second access network device serving the terminal includes aggregated access network tunnel information allocated by the second access network device to the terminal.

50. The method according to claim 47 or 48, characterized in that The access network tunnel information of the second access network device serving the terminal includes the access network tunnel information allocated by the second access network device to the first session of the terminal.

51. The method according to any one of claims 47 to 50, characterized in that The access network tunnel information of the second access network device serving the terminal is allocated by the session management function network element.

52. The method of claim 47, wherein: After determining to switch the terminal to the second access network device based on the second switching time information, the method further includes: The access network tunnel information is sent to the second access network device and / or the access and mobility management function network element.

53. A communication method, the method being applied to an access and mobility management function network element, the method comprising: Determine second switching time information of the terminal, where the second switching time information includes access time of at least one access network device corresponding to the terminal; The second switching time information is sent to a session management function network element.

54. The method according to claim 53, characterized in that The method further comprises: Acquire access network tunnel information allocated by other access network devices to the terminal, where the other access network devices include one or more access network devices other than the first access network device in the at least one access network device; The access network tunnel information allocated to the terminal by other access network devices is sent to the session management function network element.

55. A communication system, comprising an access and mobility management function network element and a session management function network element, the access and mobility management function network element being used to execute the method as described in any one of claims 53 or 54, and the session management function network element being used to execute the method as described in any one of claims 47 to 52.

56. The system according to claim 55, characterized in that The system also includes a first access network device and a second access network device, the first access network device is used to execute the method as described in any one of claims 18-29, and the second access network device is used to execute the method as described in any one of claims 1-17.

57. A communication method, applied to a session management function network element, the method comprising: receiving second information from an access and mobility management function network element, the second information including access time corresponding to the terminal accessing at least one access network device and access network tunnel information allocated by the at least one access network device to the terminal; Based on the second information, determine to switch the terminal to a second access network device; Request the user plane function network element to update the access network tunnel information of the terminal to the access network tunnel information of the second access network device serving the terminal.

58. The method according to claim 57, characterized in that The second information includes second switching time information and access network tunnel information allocated by other access network devices to the terminal, and the second switching time information includes access time of at least one access network device corresponding to the terminal.

59. The method according to claim 57, characterized in that The second information includes a correspondence between an identifier of the session of the terminal, an access time when the terminal accesses a corresponding access network device, and access network tunnel information.

60. A communication method, the method being applied to an access and mobility management function network element, the method comprising: Determining second switching time information of the terminal; Acquire access network tunnel information allocated by other access network devices to the terminal, where the other access network devices include one or more access network devices other than the first access network device in the at least one access network device; Based on the second switching time information and the access network tunnel information allocated by the other access network device to the terminal, second information is sent to the session management function network element, wherein the second information includes the access time corresponding to the terminal accessing at least one access network device and the access network tunnel information allocated by the at least one access network device to the terminal.

61. The method according to claim 60, characterized in that The second information includes second switching time information and access network tunnel information allocated by other access network devices to the terminal, and the second switching time information includes access time of at least one access network device corresponding to the terminal.

62. The method according to claim 60, characterized in that The second information includes a correspondence between an identifier of the session of the terminal, an access time when the terminal accesses a corresponding access network device, and access network tunnel information.

63. A communication device, characterized in that: Comprising means for performing the method of any one of claims 1-44, claims 47-54, or claims 57-62.

64. A communication device, characterized in that: The device comprises a processor configured to read and execute a computer program stored in a memory to implement the method according to any one of claims 1 to 44, claims 47 to 54, or claims 57 to 62.

65. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store a computer program. When the computer program is executed, the method of any one of claims 1-44, claims 47-54, or claims 57-62 is executed.

66. A computer program, characterized in that When the computer program is executed, the method of any one of claims 1-44, claims 47-54, or claims 57-62 is performed.

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