Communication method, and device

Abstract

The present application relates to a communication method, and a device. The method comprises: a terminal receiving a first message in a first radio access technology (RAT), wherein the first message is used for triggering the terminal to execute an operation related to a second RAT.

Description

Communication methods and devices Technical Field

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

[0002] As terminal capabilities continue to improve, future terminals may support multiple connectivity functions or capabilities. Such terminals can access the core network through multiple Radio Access Technologies (RATs), meaning they can transmit data with the core network via multiple access network devices, each corresponding to a different RAT. However, how to ensure service continuity and efficient data or message transmission among these multiple RATs while supporting multiple connectivity capabilities becomes a problem that needs to be solved.

[0003] Summary of the Invention

[0004] This application provides a communication method and device.

[0005] This application provides a communication method, including:

[0006] The terminal receives a first message in the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0007] This application provides a communication method, including:

[0008] The first core network device sends a first message to the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0009] This application provides a communication method, including:

[0010] The first access network device receives a first message from the first core network device, wherein the first access network device corresponds to the first RAT, and the first message is used to trigger the terminal to perform an operation related to the second RAT;

[0011] The first access network device sends the first message to the terminal.

[0012] This application provides a terminal, including:

[0013] A first communication unit is configured to receive a first message in a first RAT, wherein the first message is configured to trigger the terminal to perform an operation related to a second RAT.

[0014] This application provides a first core network device, including:

[0015] The second communication unit is used to send a first message to the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0016] This application provides a first access network device, including:

[0017] The third communication unit is configured to receive a first message from a first core network device, wherein the first access network device corresponds to a first RAT, and the first message is configured to trigger the terminal to perform an operation related to a second RAT; and to send the first message to the terminal.

[0018] This application provides a terminal, including a transceiver, a processor, and a memory. The memory stores a computer program, the transceiver communicates with other devices, and the processor calls and runs the computer program stored in the memory to enable the terminal to perform the methods described above.

[0019] This application provides a first core network device, including a transceiver, a processor, and a memory. The memory stores a computer program, the transceiver communicates with other devices, and the processor calls and runs the computer program stored in the memory to cause the first core network device to perform the aforementioned method.

[0020] This application provides a first access network device, including a transceiver, a processor, and a memory. The memory stores a computer program, the transceiver communicates with other devices, and the processor calls and runs the computer program stored in the memory to cause the first access network device to perform the above-described method.

[0021] This application provides a chip for implementing the above method.

[0022] Specifically, the chip includes a processor for retrieving and running a computer program from memory, causing a device equipped with the chip to perform the methods described above.

[0023] This application provides a computer-readable storage medium for storing a computer program, which, when run by a device, causes the device to perform the above-described method.

[0024] This application provides a computer program product, including computer program instructions that cause a computer to perform the above-described method.

[0025] By adopting the above scheme, the terminal can receive messages under one RAT to perform related operations on another RAT. Thus, when the terminal has the ability to access the network under multiple RATs, it can work collaboratively under multiple RATs, ensuring the continuity of terminal services and the efficiency of data or message transmission. Attached Figure Description

[0026] Figure 1 is a schematic diagram of an application scenario according to an embodiment of this application.

[0027] Figure 2 is a schematic diagram of the state transition scenario between the CM idle state and the CM connected state of the UE.

[0028] Figure 3 is a schematic diagram of the state transition scenario between the CM idle state and the CM connected state in AMF.

[0029] Figure 4 is a schematic flowchart of a communication method according to an embodiment of this application.

[0030] Figure 5 is a schematic flowchart of a communication method according to another embodiment of this application.

[0031] Figure 6 is a schematic flowchart of a communication method according to another embodiment of this application.

[0032] Figure 7 is a schematic diagram of a multi-access capability terminal according to an embodiment of this application.

[0033] Figures 8 to 12 are various schematic flowcharts of a communication method according to an embodiment of the present application.

[0034] Figure 13 is a schematic flowchart of assigning a NAS identifier for paging to the first connection of a UE according to an embodiment of the present application.

[0035] Figure 14 is a schematic flowchart of assigning a NAS identifier for paging to a second connection of a UE according to an embodiment of this application.

[0036] Figure 15 is a schematic flowchart of assigning the same NAS identifier for paging to different RATs of a UE according to an embodiment of the present application.

[0037] Figure 16 is a schematic block diagram of a terminal according to an embodiment of the present application.

[0038] Figure 17 is a schematic block diagram of a first core network device according to an embodiment of the present application.

[0039] Figure 18 is a schematic block diagram of a first access network device according to an embodiment of the present application.

[0040] Figure 19 is a schematic block diagram of a communication device according to an embodiment of this application.

[0041] Figure 20 is a schematic block diagram of a chip according to an embodiment of this application. Detailed Implementation

[0042] The technical solutions of this application embodiment can be applied to various communication systems, such as: LTE (Long Term Evolution), LTE-A (Long Term Evolution-Advanced), NR (New Radio), evolution of NR, WLAN (Wireless Local Area Network), WiFi (Wireless Fidelity), or other communication systems.

[0043] This application describes various embodiments in conjunction with network devices and terminals. The terminal can be mobile or fixed, and may also be referred to as a mobile station, user unit, etc. The terminal can be a station in a WLAN, or a smart terminal, wireless modem, laptop, tablet, etc. In this application embodiment, the terminal can be a VR (Virtual Reality) terminal / AR (Augmented Reality) terminal, industrial control terminal, autonomous driving terminal, telemedicine terminal, smart grid terminal, transportation safety terminal, smart city terminal, or smart home wireless terminal, etc. By way of example and not limitation, in this application embodiment, the terminal can also be a wearable device.

[0044] In this embodiment, the network device can be a device for communicating with a terminal. The network device can be an access point in a WLAN, an evolved base station in LTE, a relay station, a vehicle-mounted device, a wearable device, a network device in an NR network (gNB, the next generation Node B), a network device in a future PLMN network, or a network device in a non-terrestrial network, etc. By way of example and not limitation, in this embodiment, the network device can have mobility characteristics; for example, the network device can be a mobile device.

[0045] To facilitate understanding of the technical solutions of the embodiments of this application, the relevant technologies of the embodiments of this application are described below. The following relevant technologies are optional solutions and can be combined with the technical solutions of the embodiments of this application in any way, and they all fall within the protection scope of the embodiments of this application.

[0046] Figure 1 exemplarily illustrates a communication system 100. The communication system includes network devices 110 and terminals 120. In one possible implementation, the communication system 100 may include multiple network devices 110, and the coverage area of ​​each network device 110 may include one or more terminals 120; this embodiment does not limit this. In another possible implementation, the communication system 100 may also include other network entities such as mobility management entities and access and mobility management functions; this embodiment does not limit this. The network devices may further include access network devices and core network devices. That is, the communication system may also include multiple core networks for communicating with the access network devices. The access network devices may be base stations of LTE, LTE-A, or NR systems. Taking the communication system shown in Figure 1 as an example, the communication devices may include network devices and terminals with communication functions. The communication devices may also include other devices in the communication system, such as network controllers, mobility management entities, and other network entities; this embodiment does not limit this.

[0047] To facilitate understanding of the embodiments of this application, the basic concepts involved in the embodiments of this application are briefly explained below. It should be understood that the basic concepts introduced below do not limit the embodiments of this application.

[0048] In related technologies, connection management includes the function of establishing and releasing N1 NAS (Non-access stratum) signaling connections (or NAS connections) between a UE (User Equipment) and an AMF (Access and Mobility Management Function). The N1 NAS signaling connection enables signaling interaction between the UE and the core network. This N1 NAS signaling connection may include connections between the UE and access network equipment, and N2 connections between the access network equipment and the AMF for the UE.

[0049] The N1 NAS signaling connection between the UE and the AMF includes the following two states: CM (Connection Management) - IDLE (idle or idle state) and CM - CONNECTED (connected or connected state).

[0050] When the UE is in CM-IDLE, there are no corresponding N1, AN (Access Network) signaling, N2, or N3 connections. If the UE is simultaneously in CM-IDLE and RM (Registration Management)-REGISTERED states, the UE needs to initiate a service request procedure to respond to paging, unless the UE is in MICO (Mobile Initiated Connection Only) mode; or, if the UE is simultaneously in CM-IDLE and RM (Registration Management)-REGISTERED states, it initiates a service request procedure when it has uplink signaling or data to send. Correspondingly, when the UE state on the AMF side is RM-REGISTERED, the information required for network-to-UE communication is stored in the AMF, which can obtain this information through the 5G-GUTI (5G Globally Unique Temporary Identifier). The UE will provide AN parameters such as 5G-S-TMSI during the AN signaling connection establishment process. Additionally, when the UE is in CM-IDLE state, it can enter MICO mode to reduce power consumption and signaling overhead.

[0051] The state transition between CM-IDLE (idle state) and CM-CONNECTED (connected state) of the N1 NAS signaling connection between the UE and AMF can be shown in Figures 2 and 3.

[0052] As shown in Figure 2, when the UE is in CM-IDLE state, it should enter CM-CONNECTED state whenever an AN signaling connection is established. Specifically, when the UE is in CM-IDLE state, it sends an initial NAS signaling message (e.g., any one of Registration Request, Service Request, or Deregistration Request) to initiate the transition from CM-IDLE state to CM-CONNECTED state on the UE side.

[0053] When a UE is in CM-CONNECTED state, an N1 NAS signaling connection exists between the UE and the AMF. This N1 NAS signaling connection utilizes the RRC (Radio Resource Control) connection between the UE and the NG-RAN, and the NGAP (Next Generation Application Protocol) UE association between the AN and the AMF. A UE can be in CM-CONNECTED state without the NGAP being bound to any transport network layer. After the NAS signaling process is completed, the AMF can decide to release the NAS signaling connection with the UE. As shown in Figure 2, when a UE is in CM-CONNECTED state, the UE enters the CM-IDLE state whenever the AN signaling connection is released; and / or the logical NGAP signaling connection and the UE's N3 user plane connection enter the CM-IDLE state after the AN is released.

[0054] As shown in Figure 3, when the UE state stored in the AMF is CM-IDLE or RM-REGISTRATION, the AMF needs to initiate a paging process to the UE and receive a response when it needs to send signaling or data to the UE, thus executing the service request procedure initiated by the network side. On the AMF side, whenever an N2 connection is established and / or an N2 context is established for a UE, the UE's state in the AMF will enter the CM-CONNECTED state. That is, the initial reception of an N2 message will initiate the transition of the UE state stored in the AMF from CM-IDLE to CM-CONNECTED. The AMF can maintain the UE connection state in CM-CONNECTED until the UE deregisters from the network, i.e., when the N2 context is released, the UE state stored in the AMF will transition from CM-CONNECTED to CM-IDLE.

[0055] In addition, a UE in CM-CONNECTED state can also be in RRC_INACTIVE state. In this state, the RAN releases the AN connection with the UE, and the UE moves within the area configured by the RAN. The N2 connection remains, and the UE's reachability is managed by the RAN based on auxiliary information provided by the network side. UE paging is managed by the RAN, and the UE listens for paging messages containing its corresponding network identifier (5G S-TMSI) and the RAN identifier. When the UE leaves the area configured by the RAN, it needs to notify the RAN. UE reachability management is responsible for detecting whether the UE is reachable and providing the network with the UE's location (i.e., access node) so that information sent by the network can reach the UE. This process is accomplished through paging the UE and UE location tracking. UE location tracking includes UE registration area tracking (i.e., UE registration area update) and UE reachability tracking (i.e., UE periodic registration area update). This function can be configured in 5GC (in CM-IDLE state) or NG-RAN (in CM-CONNECTED state). The UE and AMF negotiate the UE reachability characteristics in the CM-IDLE state during the registration process.

[0056] Whenever a UE in RM-REGISTERED state enters CM-IDLE state, the UE starts a periodic registration timer based on the periodic registration timer allocated by the AMF during the registration process. The UE needs to perform periodic registration upon the expiration of the periodic registration timer. If the UE moves out of network coverage when its periodic registration timer expires, the UE should perform the registration process upon its next return to coverage.

[0057] The AMF runs a mobile reachability timer for the UE. Whenever a UE in the RM-REGISTERED state changes its CM state to CM-IDLE, the timer starts with a value longer than the UE's periodic registration timer. If the AMF receives an elapsed time from the RAN when the RAN initiates a UE context release indicating the UE is unreachable, the AMF should derive the mobile reachability timer value based on the elapsed time received from the RAN and the normal mobile reachability timer value. If the UE's CM state in the AMF moves to the CM-CONNECTED state, the AMF stops the mobile reachability timer. If the mobile reachability timer expires, the AMF determines the UE is unreachable. When the mobile reachability timer expires, the AMF cannot know whether the UE is only temporarily unreachable, and therefore will not immediately register the UE. The AMF clears the paging processing indicator bit and starts the implicit deregistration timer only after the mobile reachability timer expires. If the UE becomes CM-CONNECTED before the timer expires, the AMF should stop the implicit registration timer and set the PPF. Otherwise, after the implicit registration timer expires, the AMF initiates the UE's privacy deregistration.

[0058] If the UE indicates the duration of the unavailability period, the AMF will consider the UE unreachable and will not trigger a paging procedure until the UE re-registers for normal service. Once the event causing the UE to become unavailable is completed or canceled within the UE, the UE will initiate a registration procedure to restore normal service. If the UE's CM state in the AMF is CM-IDLE, the AMF considers a UE in RM-REGISTERED to be reachable via CN paging, unless the UE applies MICO mode or the UE has indicated the duration of the unavailability period.

[0059] Figure 4 is a schematic flowchart of a communication method according to an embodiment of this application. The method includes at least a portion of the following.

[0060] S410, The terminal receives a first message in the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0061] Figure 5 is a schematic flowchart of a communication method according to an embodiment of this application. The method includes at least a portion of the following.

[0062] S510, the first core network device sends a first message to the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0063] Figure 6 is a schematic flowchart of a communication method according to an embodiment of this application. The method includes at least a portion of the following.

[0064] S610. The first access network device receives a first message from the first core network device, wherein the first access network device corresponds to the first RAT, and the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0065] S620, the first access network device sends the first message to the terminal.

[0066] The first access network device and the first core network device may belong to the same network, such as the first network. The first core network device may be a control plane network element on the core network side of the first network, and the control plane network element may include one of the following: MM (Mobility Management) network element, AMF, etc.

[0067] The terminal can be a terminal with multi-access capability. This terminal with multi-access capability can be called a multi-access device, a dual-access device, or a multi-access UE, etc. A terminal with multi-access capability can be a single-SIM terminal or a multi-SIM terminal; a single-SIM terminal refers to a terminal with a single USIM (Universal Subscriber Identity Module) card, while a multi-SIM terminal refers to a terminal with multiple USIM cards. For example, referring to Figure 7, one MS (Mobile Station), i.e., one terminal, can be configured with USIM-1 and USIM-2, and can connect to access network devices in access networks AN-1 and AN-2 through the uu interface (air interface) to access the core network through AN-1 and AN-2 respectively.

[0068] Multi-access capability can include the ability to access the core network through multiple RATs and / or the ability to access the core network through multiple access network devices. These access network devices can belong to the same RAT or different RATs. Specifically, the ability to access the core network through multiple RATs can mean accessing the core network through the access network devices corresponding to each RAT. For terminals with multi-access capability, all access network devices in the multiple RATs accessed by the terminal are connected to the core network. Connections corresponding to the terminal exist between the control plane network elements on the core network side and the different access network devices. Furthermore, the signaling transmission on the multiple access network devices is independent. The collaborative operation between the connections corresponding to the terminal and the different access network devices mainly occurs on the network side. The connection between any access network device corresponding to the terminal and the control plane network elements can be an NGAP connection.

[0069] When a terminal with multi-access capability registers with the core network through any access network device corresponding to any RAT, it can be said that the terminal has or has established one leg. Here, the registration of a multi-access capable terminal with the core network through any access network device corresponding to any RAT can be interpreted as the terminal connecting to the core network through any access network device corresponding to any RAT and establishing a corresponding context at the corresponding network element in the core network.

[0070] The term "connection" in this context can refer broadly to the connection between the terminal and the core network. It can also be alternatively referred to as the terminal's higher-level connection or logical connection. In the following text, "connection" can refer to the terminal registering with the core network through the access network equipment (and establishing a context on the corresponding network element on the core network side), and will not be repeated hereafter. In this application, "connection," "higher-level connection," and "logical connection" have the same meaning and will not be repeated hereafter.

[0071] Each leg of the terminal can include at least one of the following: a NAS signaling connection (or NAS connection, or N1 NAS connection) between the terminal and the core network, a user plane connection or user plane resources between the terminal and the core network. It should be noted that different legs of the terminal correspond to different access network devices. Furthermore, the control plane network elements of the core network corresponding to different legs of the terminal can be the same or different, the user plane network elements of the core network corresponding to different legs of the terminal (such as UPF (User Plane Function)) can be the same or different, and the RATs corresponding to different legs of the terminal can be the same or different.

[0072] For example, when a terminal registers with the core network through access network devices corresponding to two RATs, the terminal can be said to have or have established two legs, namely a first leg and a second leg. The first leg of the terminal may include at least one of the following: a NAS connection established between the terminal and a first control plane network element through the first access network device corresponding to the first RAT; or a user plane connection or user plane resource established between the terminal and a first user plane network element through the first access network device corresponding to the first RAT. The second leg of the terminal may include at least one of the following: a NAS connection established between the terminal and a second control plane network element through the second access network device corresponding to the second RAT; or a user plane connection or user plane resource established between the terminal and a second user plane network element through the second access network device corresponding to the second RAT. Here, the first control plane network element and the second control plane network element may be the same or different, the first user plane network element and the second user plane network element may be the same or different, the number of first user plane network elements may be one or more, and the number of second user plane network elements may be one or more; this embodiment does not limit these.

[0073] For example, when a terminal connects to the core network through two access network devices of a single RAT and establishes two contexts at corresponding network elements in the core network, the terminal can be said to have or have established two legs, namely a first leg and a second leg. The first leg of the terminal may include at least one of the following: a NAS connection established between the terminal and a first control plane network element through the first access network device; a user plane connection or user plane resource established between the terminal and a first user plane network element through the first access network device. The second leg of the terminal may include at least one of the following: a NAS connection established between the terminal and a second control plane network element through the second access network device; a user plane connection or user plane resource established between the terminal and a second user plane network element through the second access network device. Here, the first and second access network devices correspond to the same RAT; the first and second control plane network elements may be the same or different; the first and second user plane network elements may be the same or different; the number of first user plane network elements may be one or more; the number of second user plane network elements may be one or more; this embodiment does not limit these limitations.

[0074] In some possible implementations, triggering the terminal to perform operations related to the second RAT may include triggering the terminal to establish a NAS connection in the second RAT. That is, the first message is used to trigger the terminal to establish a NAS connection in the second RAT.

[0075] The first message may carry at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, or the RAT corresponding to the downlink message to be transmitted; a first timer, wherein the duration of the first timer is one of the following: the maximum duration for the terminal to initiate or complete the establishment of a NAS connection in the second RAT, or the maximum duration for the terminal to initiate or complete the establishment of user plane resources in the second RAT.

[0076] In some embodiments, the first RAT is the same as the second RAT.

[0077] If the terminal and network side manage multiple access connections for the terminal at the RAT granularity, the triggering reason for the first core network device to send the first message may be that there is a downlink message to be transmitted under the first RAT that needs to be sent to a terminal that is idle under the first RAT, and / or the user plane network element receives downlink data to be transmitted for the first session corresponding to the first RAT that needs to be sent to the terminal, and the user plane network element does not store the tunnel information of the first session. The downlink message to be transmitted may refer to downlink NAS signaling to be transmitted, or downlink NAS message to be transmitted, etc. The specific content of the downlink message to be transmitted can be many kinds, for example, it may include any of the following: N1 signaling to be sent to the terminal, SMS message to be sent to the terminal, user plane connection activation message of the first session (to transmit mobile terminal user data), etc., without limitation or exhaustive list here. The terminal being idle under the first RAT may refer to the terminal's connection state being idle under the first RAT. On the first core network device side, the connection status of the terminal under the first RAT can be determined as follows: if the terminal does not have a NAS connection under the first RAT, the first core network device determines that the connection status of the terminal under the first RAT is connection management idle state; and / or, the connection status contained in the context corresponding to the first RAT in the terminal's local storage by the first core network device is connection management idle state.

[0078] If the terminal and network side manage multiple access connections for the terminal at the connection (i.e., logical connection) granularity, the triggering reason for the first core network device to send the first message may include: there is a downlink message to be transmitted that needs to be sent to the terminal through the first access network device corresponding to the first logical connection, and the terminal is in an idle state under the first logical connection; and / or the downlink data to be transmitted for the first session received by the user plane network element needs to be sent to the terminal through the access network device corresponding to the first logical connection, and the user plane network element does not store the tunnel information of the first session. The first access network device corresponds to the first RAT.

[0079] The terminal being in an idle state under the first logical connection can refer to the terminal's connection status under the first logical connection being a connection management idle state. On the first core network device side, the connection status of the terminal under the first logical connection can be determined in the following ways: if the first core network device determines the terminal's connection status under the first logical connection to be a connection management idle state when there is no corresponding NAS connection for the terminal under the first logical connection; and / or, the first core network device stores the connection status as a connection management idle state in the context corresponding to the first logical connection within the terminal's local context.

[0080] The first core network device sends a first message to the first access network device corresponding to the first RAT, including: the first core network device sends a second paging message to the first access network device corresponding to the first RAT, wherein the second paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

[0081] The processing of the first access network device receiving the first message from the first core network device may include: the first access network device receiving a second paging message from the first core network device, wherein the second paging message carries the first message, and the first message carries a NAS identifier for paging corresponding to the first RAT. The first access network device sending the first message to the terminal may include: the first access network device sending a first paging message to the terminal, wherein the first paging message carries the first message.

[0082] The terminal receiving a first message in the first RAT includes: the terminal receiving a first paging message from the first access network device corresponding to the first RAT, wherein the first paging message carries the first message and the first message carries the NAS identifier for paging corresponding to the first RAT.

[0083] The first core network device may determine the first access network device in the following ways: by using an access network device that belongs to the terminal's registration area under the first RAT as the first access network device; or by using the access network device that the terminal last accessed under the first RAT as the first access network device.

[0084] Optionally, if the terminal is managed with multiple access connections at the RAT level, the first message may carry at least one of the following: the NAS identifier for paging corresponding to the first RAT, the type information of the second RAT, and the first timer.

[0085] The NAS identifier used for paging can also be called the NAS identifier for the paging terminal, or the NAS identifier for the terminal, etc. The NAS identifier used for paging can include at least one of the following: GUTI (Globally Unique Temporary Identifier), 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier). The NAS identifier used for paging corresponding to the first RAT can include at least one of the following: the GUTI corresponding to the first RAT, or the 5G-S-TMSI corresponding to the first RAT.

[0086] Since the first RAT and the second RAT are the same in this embodiment, the type information of the second RAT carried in the first message is specifically the type information of the first RAT. In this embodiment, the type information of the RAT is used to identify the transmission technology corresponding to the access network. For example, the type information of the first RAT can be any one of the following: E-UTRA (Evolved Universal Terrestrial Radio Access), NR terrestrial access, NR satellite access, 6G access, etc. NR terrestrial access can also be referred to as the transmission technology corresponding to the TN (Terrestrial Network) access network; NR satellite access can also be referred to as the transmission technology corresponding to the NTN access network. NR satellite access can include at least one of NR (LEO), NR (GEO), NR (LEO), etc.

[0087] It should be noted that if the first core network device pre-assigns different NAS identifiers for paging to the terminal in different RATs, the first message may not carry the type information of the first RAT. The terminal can determine under which RAT there is a message to be transmitted or a first session with downlink data to be transmitted by using the NAS identifier for paging corresponding to the first RAT. If the first core network device pre-assigns the same NAS identifier for paging to the terminal in different RATs, then the first message needs to carry the type information of the first RAT so that the terminal can determine under which specific RAT there is a message to be transmitted or a first session with downlink data to be transmitted.

[0088] Optionally, if the terminal is managed with multiple access connections at the connection level, the first message may carry at least one of the following: the NAS identifier for paging corresponding to the first RAT, the connection identifier of the second connection of the second RAT, and the first timer.

[0089] The NAS identifier for paging corresponding to the first RAT may refer to the NAS identifier for paging corresponding to the first logical connection, which corresponds to the first access network device and the first access network device corresponds to the first RAT.

[0090] The connection identifier of the second connection of the second RAT can specifically refer to the connection identifier of the first logical connection. It should be noted that if the first core network device pre-assigns different NAS identifiers for paging to the terminal in different logical connections, where different logical connections correspond to different access network devices, and different access network devices correspond to the same or different RATs, then the first message may not carry the connection identifier corresponding to the first logical connection. The terminal can determine under which logical connection there is a message to be transmitted or a first session with downlink data to be transmitted through the NAS identifier for paging corresponding to the first logical connection. If the first core network device assigns the same NAS identifier for paging to the terminal under different logical connections, then the first message needs to carry the connection identifier corresponding to the first logical connection so that the terminal can determine under which specific logical connection there is a message to be transmitted or a first session with downlink data to be transmitted.

[0091] In scenarios where multiple access connections are managed at the connection level, the first message may or may not carry the type information of the RAT (the type information of the first RAT).

[0092] The second paging message also carries a registration area list, wherein the registration area list is used by the first access network device to determine the cell from which the terminal is being paged.

[0093] Preferably, the list of registered areas can be the list of registered areas corresponding to the first RAT (or the registered area corresponding to the first RAT). For example, the list of registered areas corresponding to the first RAT may include at least one of the identifier or ID of the last visited cell corresponding to the first RAT, the TAI (Tracking Area Identity) of the last visited cell, or the RA (Registration Area) specific to the first RAT.

[0094] Optionally, the registration area list may include the registration area corresponding to each RAT in one or more RATs of the terminal. Each registration area corresponding to each RAT may consist of at least one of the following: one or more TAIs corresponding to each RAT, the identifier of the last accessed cell corresponding to each RAT, the last accessed TAI corresponding to each RAT, and a dedicated RA for each RAT. The registration area corresponding to each RAT in the one or more RATs in the registration area list may be allocated to the terminal during the initial registration process. This embodiment does not limit the specific allocation or generation method.

[0095] After receiving the second paging message, the first access network device can determine the first cell of the paging terminal under the first RAT based on the registered area list. For example, after receiving the second paging message, the first access network device can extract the registered area list corresponding to the first RAT, and determine at least one of the identifier of the last accessed cell, the last accessed TAI, and the RA dedicated to the first RAT based on the registered area list corresponding to the first RAT; then, based on at least one of the identifier of the last accessed cell, the last accessed TAI, and the RA dedicated to the first RAT, determine the first cell (or first area, etc.) of the paging terminal. Accordingly, the first access network device sending the first paging message to the terminal can be: the first access network device sends the first paging message to the terminal under the first cell (or first area, etc.).

[0096] After the terminal receives the first message from the first RAT, the method further includes: the terminal sending a second message to the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection on the second RAT. Specifically, the second message can be a message used to initiate a service request process; for example, the second message can be a service request message or a service request.

[0097] The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

[0098] In this embodiment, the first RAT and the second RAT are the same. Therefore, the terminal sending the second message to the second access network device corresponding to the second RAT can refer to the terminal sending the second message to the first access network device corresponding to the first RAT. The second message is used to establish a NAS connection in the first RAT.

[0099] If the terminal performs multi-access connection management at the RAT level, the second message may carry at least one of the following: the NAS identifier for paging corresponding to the first RAT, or the identifier of the session that the terminal recognizes is allowed to be activated on the first RAT.

[0100] If multiple access connection management is performed on a connection-by-connection basis for the terminal, the second message may carry at least one of the following: the NAS identifier for paging corresponding to the first RAT, and the identifier of the session allowed to be activated on the first RAT as identified by the terminal. Specifically, the NAS identifier for paging corresponding to the first RAT is the NAS identifier for paging corresponding to the first logical connection, which corresponds to the first access network device, and the first access network device corresponds to the first RAT; the identifier of the session allowed to be activated on the first RAT as identified by the terminal is the identifier of the session allowed to be activated on the first logical connection as identified by the terminal.

[0101] The processing by the first access network device may include: the first access network device receiving a second message from the terminal; the first access network device sending the second message to the first core network device. The processing by the first core network device after the first RAT sends the first message may include: the first core network device receiving the second message sent by the terminal through the first access network device corresponding to the first RAT. Here, "the first access network device sending the second message to the first core network device" may mean that the first access network device forwards the second message to the first core network device through an N2 message, which may carry the second message.

[0102] Optionally, the first RAT is the RAT corresponding to the downlink message to be transmitted, and the network side manages multiple access connections for the terminal at the RAT granularity. The second message can be used to indicate that the terminal requests to establish a NAS connection with the first core network device through the first access network device under the first RAT. The second message can carry the NAS identifier for paging corresponding to the first RAT.

[0103] After receiving the second message, the first core network device can establish a NAS connection under the first RAT with the terminal through the first access network device. In this example, the NAS connection between the terminal and the first core network device under the first RAT is referred to as the first NAS connection or the first NAS connection under the first RAT. After completing the establishment of the first NAS connection, the first core network device sends downlink messages (downlink NAS messages) to the terminal through the first NAS connection.

[0104] It should be noted that the first message may also carry a first timer. In this case, if the duration of the first timer is the maximum duration for the terminal to initiate the establishment of a NAS connection in the second RAT (the same as the first RAT in this example), the terminal can start timing when it receives the first message and needs to complete sending the second message within the duration of the first timer; the first core network device can also start timing when it sends the first message and detect whether the second message has been received within the duration of the first timer. If the duration of the first timer is the maximum duration for the terminal to complete the establishment of the first NAS connection in the first RAT, the terminal can start timing when it receives the first message and needs to complete sending the second message and completing the establishment of the first NAS connection under the first RAT within the duration of the first timer; the first core network device can also start timing when it sends the first message and detect whether the establishment of the first NAS connection has been completed within the duration of the first timer.

[0105] Optionally, the first logical connection is the connection corresponding to the downlink message to be transmitted, and the terminal performs multi-access connection management at the connection granularity. The second message can be used to indicate that the terminal requests the first access network device and the first core network device corresponding to the first logical connection to establish a NAS connection. The second message can carry a NAS identifier for paging corresponding to the first logical connection.

[0106] After receiving the second message, the first core network device can establish a NAS connection corresponding to the first logical connection with the terminal through the first access network device (the NAS connection is referred to as the first NAS connection); after the establishment of the first NAS connection is completed, a downlink message (downlink NAS message) is sent to the terminal through the first NAS connection.

[0107] In addition, if the first message also carries a first timer, the relevant explanations regarding the relationship between the timing duration of the first timer and sending the second message or establishing the first NAS connection are similar to the previous examples and will not be repeated here.

[0108] Optionally, the first RAT is the RAT corresponding to a first session with downlink data to be transmitted, and the network side manages multiple access connections for the terminal at the RAT level. The second message can be used to indicate that the terminal requests to establish a NAS connection with the first core network device through the first access network device under the first RAT; and the second message is also used to establish user plane resources corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session. The second message carries the NAS identifier for paging corresponding to the first RAT and the identifier of the session that the terminal recognizes is allowed to be active on the first RAT.

[0109] In this application, "session" may refer to a PDU session, which will not be explained again below.

[0110] The identifier of the session that the terminal identifies as allowed to be activated on the first RAT may refer to the identifier of each PDU session among one or more PDU sessions that the terminal identifies as being able to be activated on the first RAT, or the list of allowed PDU sessions that the terminal identifies as being able to be activated on the first RAT.

[0111] After receiving the second message, the first core network device can establish a first NAS connection under the first RAT with the terminal through the first access network device. After the establishment of the first NAS connection is completed, the first core network device determines whether the first session identified by the terminal as allowed to be activated on the first RAT includes a first session with downlink data to be transmitted, based on the identifier of the session identified by the terminal as allowed to be activated on the first RAT. If so, the first session is determined to activate the UP (User Plane) connection, and a session management network element (such as a user plane network element (UPF)) is requested to establish user plane resources for the first session.

[0112] Additionally, the method may include: if the first core network device determines that the sessions identified by the terminal that are allowed to be activated on the first RAT do not include a first session with pending downlink data transmission, the first core network device may notify the session management network element that the terminal is unreachable on the current first RAT. For example, after the first core network device notifies the session management network element that the terminal is unreachable on the first RAT, the method may further include: the first core network device pageing the terminal on other RATs based on at least one of local configuration, the terminal's subscription information, or a request from the session management network element.

[0113] It should be noted that the first message may also carry a first timer. In this case, if the duration of the first timer is the maximum duration for the terminal to initiate the establishment of user plane resources in the second RAT (the same as the first RAT in this example), the terminal can start timing when it receives the first message and needs to complete sending the second message within the duration of the first timer. The first core network device can also start timing when it sends the first message and detect whether the second message has been received within the duration of the first timer. If the duration of the first timer is the maximum duration for the terminal to complete the establishment of user plane resources in the first RAT, the terminal can start timing when it receives the first message and needs to complete sending the second message within the duration of the first timer and complete the establishment of user plane resources under the first RAT. The first core network device can also start timing when it sends the first message and detect whether the establishment of user plane resources has been completed within the duration of the first timer. In addition, if the first core network device does not receive the second message within the timeout period of the first timer, or determines that the establishment of the first NAS connection has not been completed, or determines that the establishment of user plane resources has not been completed, the first core network device determines to further page the terminal according to the relevant policy. The relevant policy can be configured according to the actual situation, and this embodiment does not limit it.

[0114] Optionally, the first logical connection is a connection corresponding to a first session with downlink data to be transmitted, and the network side manages multiple access connections for the terminal at the connection level. The second message can be used to indicate that the terminal requests to establish a NAS connection corresponding to the first connection through the first access network device and the first core network device under the first RAT; and the second message is also used to establish user plane resources corresponding to the first logical connection for receiving downlink data to be transmitted in the first session. The second message carries a NAS identifier for paging corresponding to the first logical connection and an identifier of the session that the terminal recognizes is allowed to be active on the first logical connection.

[0115] After receiving the second message, the first core network device can establish a first NAS connection corresponding to the first logical connection with the terminal through the first access network device. After the establishment of the first NAS connection is completed, the first core network device determines whether the first session that the terminal has identified as allowed to be activated on the first logical connection includes a first session with downlink data to be transmitted, based on the identifier of the session that the terminal has identified as allowed to be activated on the first logical connection. If so, the first session that has activated the UP connection is determined, and the session management network element is requested to establish user plane resources for the first session.

[0116] Additionally, the method may include: if the first core network device determines that the sessions identified by the terminal that are allowed to be activated on the first logical connection do not include a first session with pending downlink data transmission, the first core network device may notify the session management element that the terminal is unreachable on the current first logical connection. Further, after the first core network device notifies the session management element that the terminal is unreachable on the current first logical connection, the method may further include: the first core network device paging the terminal on other RAT connections based on at least one of local configuration, the terminal's subscription information, or a request from the session management element.

[0117] If the first message also carries a first timer, the explanation regarding the duration of the first timer and its relationship with sending the second message or establishing a user plane resource is similar to the previous example and will not be repeated here.

[0118] Referring to Figure 8, taking the first core network device as MM and the terminal as UE as an example, the communication method provided in this embodiment will be described exemplarily:

[0119] Step 801: The MM sends a paging message to the first access network device (or RAN) corresponding to the first RAT to page the UE.

[0120] For example, for a UE that performs connection management based on RAT (i.e., multi-access connection management at the RAT granularity), when the network has NAS messages related to the first RAT (e.g., sending N1 signaling, mobile terminal SMS, or user plane connection activation of PDU session to the UE (to transmit mobile terminal user data)) or data transmitted on this first RAT (e.g., when the UPF receives downlink data of the first PDU session, but the UPF does not store the tunnel info of the first PDU session), it needs to be sent to the UE that is idle on the first RAT. In this case, step 801 can be executed.

[0121] For example, for a UE that performs connection management based on connections (i.e., multi-access connection management at the connection level), when the network has NAS messages related to the first logical connection (e.g., sending N1 signaling, mobile terminal SMS, or user plane connection activation of a PDU session to the UE (to transmit mobile terminal user data)) or data transmitted on this first logical connection (e.g., when the UPF receives downlink data of the first PDU session, but the UPF does not store the tunnel info of the first PDU session), it needs to be sent to the UE that is idle on the first logical connection. In this case, step 801 can be executed.

[0122] Sending a paging message from the MM to the first access network device corresponding to the first RAT can mean that the MM sends a paging message to the first access network device within the UE's registration area in the first RAT, or to the first access network device corresponding to the TAI last accessed by the UE in the first RAT. In this step, the paging message sent by the MM to the first access network device can be the second paging message in the aforementioned embodiment.

[0123] In this step, the paging message sent by the MM to the first access network device may include the first message and the Registration Area list.

[0124] The first message may include at least one of the following:

[0125] The GUTI can be a NAS identifier for paging corresponding to the first RAT (i.e., a NAS identifier for paging the UE on the first RAT) or a NAS identifier for paging corresponding to the first logical connection.

[0126] The type information of the first RAT (RAT type) is used to indicate whether there is downlink information that needs to be sent to the UE on the NAS connection corresponding to the first RAT, or whether there is downlink data packet that needs to be sent to the UE on the user plane resources (N3 tunnel and DRB) corresponding to the first RAT.

[0127] The connection ID corresponding to the first logical connection is used to indicate whether there is downlink information that needs to be sent to the UE on the NAS connection corresponding to the first logical connection, or whether there is downlink data packet that needs to be sent to the UE on the user plane resources (N3 tunnel and DRB) corresponding to the first logical connection.

[0128] It should be noted that if the MM assigns different NAS identifiers for paging to different RATs (or different NAS identifiers for paging to different logical connections), then the paging message may not contain the RAT type (or connection ID), but instead uses the NAS identifier corresponding to this RAT or logical connection to paging the UE. If the MM uses the same NAS identifier for paging for all RATs or logical connections of the UE, then the RAT type or connection ID needs to be carried to indicate to the UE that the network needs to send a downlink NAS message on a specific RAT or logical connection, or establish user plane resources to receive downlink data.

[0129] Step 802: The first access network device sends a paging message to the UE (i.e., the first paging message in the aforementioned embodiment). The paging message may carry a first message (such as GUTI, etc.), and the relevant description of the first message is the same as in step 801, so it will not be repeated here.

[0130] Step 803: After receiving a paging message from the first access network device, the UE initiates a service request process to the MM through the first access network device to establish a first NAS connection with the MM on the first RAT (or the first logical connection).

[0131] The UE carries at least one of the following parameters in the service request message (i.e., the second message) sent in the service request process: List of Allowed PDU Sessions, which are PDU sessions identified by the UE that can be activated on the RAT (or on the user plane resources corresponding to the NAS connection); 5G-S-TMSI, which is the NAS identifier for paging corresponding to the first RAT or the NAS identifier for paging corresponding to the first logical connection.

[0132] After receiving a service request message, the MM can determine the PDU session for which the UP connection should be activated based on the service request message, and request the session management network element to establish user plane resources for the PDU session. If the MM finds that the List of Allowed PDU Sessions does not contain a PDU session that needs to send downlink data, it can notify the session management network element that the UE is unreachable on the current RAT (or NAS connection). In this case, the MM can page the UE on another RAT (or NAS connection) based on local configuration, UE subscription information, or the request from the session management network element, which is equivalent to migrating the session to another RAT.

[0133] By adopting the above embodiments, the first core network device can page the terminal individually or separately on each RAT without considering the connection status of other RATs. This helps the network select the appropriate RAT to establish a NAS connection and / or use user plane resources for the transmission of specific types of data according to the RAT characteristics. For example, data requiring wide broadcast can be transmitted through the NTN access network, while some high-speed, low-latency services need to be transmitted through the terrestrial access network. When the terminal is in a connected state on the NTN access network and in an idle state on the TN access network, it is not necessary to send NAS messages to the terminal through the NTN access network with a long delay. Instead, the UE can be paged directly through the terrestrial network more quickly, allowing the terminal to access the TN network more rapidly.

[0134] In some embodiments, the first RAT is different from the second RAT.

[0135] If multi-access connection management for terminals is performed at the RAT level, the triggering reason for the first core network device to send the first message may include one of the following: there is a downlink message to be transmitted under the second RAT that needs to be sent to a terminal that is idle under the second RAT, and the terminal cannot be paged under the second RAT; the user plane network element receives downlink data to be transmitted for the first session corresponding to the second RAT that needs to be sent to the terminal, and the terminal cannot be paged under the second RAT. The reasons why the terminal cannot be paged under the second RAT may include at least one of the following: paged terminal failed on the second RAT; the RAT corresponding to the terminal's last registered TAI is not the second RAT on which the network needs to send downlink signaling or data; the current terminal location is not within the coverage area of ​​the second RAT; the terminal is not within the dedicated registration area allocated to the second RAT. The method by which the first core network device determines the first RAT may include one of the following: determining the first RAT based on the terminal's current location; determining the corresponding first RAT based on the RAT of the terminal's last network access; determining the first RAT based on the access network device the terminal last accessed; or using the RAT currently in a connected state as the first RAT.

[0136] If multi-access connection management is performed on a connection-by-connection basis, the triggering reason for the first core network device to send the first message may include one of the following: there is a downlink message to be transmitted under the second logical connection that needs to be sent to a terminal that is idle under the second logical connection, and the terminal cannot be paged under the second logical connection; the user plane network element receives downlink data to be transmitted for the first session corresponding to the second logical connection that needs to be sent to the terminal, and the terminal cannot be paged under the second logical connection. Here, the second logical connection corresponds to the second access network device, and the second access network device corresponds to the second RAT. The reason why the terminal cannot be paged under the second logical connection may include at least one of the following: paged terminal failed on the second logical connection; the connection of the RAT corresponding to the terminal's last registered TAI is not a second logical connection on which the network needs to send downlink signaling or data; the current terminal location is not within the coverage area of ​​the second access network device corresponding to the second logical connection; the terminal is not within the dedicated registration area allocated to the second RAT.

[0137] In one embodiment, if the terminal is in an idle state on the first RAT or the first logical connection, the first core network device can trigger the terminal to establish a NAS connection on the second RAT by paging.

[0138] The first core network device can carry the first message through the second paging message. Correspondingly, the terminal receives the first message carried by the first paging message from the first access network device. The transmission of the second paging message and the first paging message is the same as described in the previous embodiments, that is, both the second paging message and the first paging message carry the first message. The second paging message also carries the registration area list, which will not be elaborated here.

[0139] It should be noted that when the first core network device sends the second paging message, it may send the second paging message to one or more access network devices. These one or more access network devices can be all access network devices within the registered area corresponding to the first RAT, or the access network device corresponding to the TAI last accessed by the terminal in the first RAT, or the access network device corresponding to the cell last accessed by the terminal in the first RAT. The terminal may receive the first paging message from only one access network device. In this embodiment, the access network device from which the terminal receives the paging message is referred to as the first access network device, and this will not be explained again below.

[0140] Optionally, if the network side manages multiple access connections to the terminal at the RAT level, the first message may carry at least one of the following: the NAS identifier for paging corresponding to the first RAT, the type information of the second RAT, and the first timer.

[0141] Optionally, if the network side manages multiple access connections for the terminal at the connection level, the first message may carry at least one of the following: a NAS identifier for paging corresponding to the first logical connection, a connection identifier for the second logical connection, and a first timer; the first logical connection corresponds to a first access network device, the first access network device corresponds to a first RAT, the second logical connection corresponds to a second access network device, and the second access network device corresponds to a second RAT. In this case, the first message may or may not carry the type information of the second RAT.

[0142] In one embodiment, if the terminal is in a connected state on the first RAT or the first logical connection, the first core network device can trigger the terminal to establish a NAS connection on the second RAT through a NAS notification message.

[0143] Optionally, multi-access connection management is performed on the terminal at the RAT level. The first core network device sends a first message on the first RAT, including: the first core network device sends a NAS notification message to the terminal through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message. The terminal receives the first message on the first RAT, including: the terminal receives a NAS notification message from the first core network device through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message.

[0144] The first access network device receives a first message from a first core network device, including: the first access network device receiving a NAS notification message from the first core network device, wherein the NAS notification message carries the first message. The first access network device sends the first message to the terminal, including: the first access network device sending the NAS notification message to the terminal.

[0145] The first message may carry at least one of the following: type information of the second RAT, and the first timer. For example, the first message may only carry the type information of the second RAT. Or, the first message may carry both the type information of the second RAT and the first timer.

[0146] Optionally, multi-access connection management is performed on a connection-by-connection basis for the terminal. The first core network device sends a first message in the first RAT, including: the first core network device sends a NAS notification message to the terminal through the first access network device corresponding to the first logical connection, wherein the first access network device corresponds to the first RAT, and the NAS notification message carries the first message. The terminal receives the first message in the first RAT, including: the terminal receives the NAS notification message from the first core network device through the first access network device corresponding to the first logical connection.

[0147] The processing of the first access network device may include: the first access network device receiving a NAS notification message from the first core network device; and the first access network device sending the NAS notification message to the terminal.

[0148] The first message may carry at least one of the following: the connection identifier of the second logical connection and the first timer. For example, the first message may carry only the connection identifier of the second logical connection. Alternatively, the first message may carry both the connection identifier of the second logical connection and the first timer. Yet another example is that the first message may carry the type information of the second RAT, the connection identifier of the second logical connection, and the first timer.

[0149] In this embodiment, the first access network device acts only as a forwarding node or transparent transmission node to transmit NAS signaling between the first core network device and the terminal, without needing to perform intermediate processing. Furthermore, in this embodiment, the NAS notification message may only include the first message, or it may include the first message and other messages. These other messages can be content specified in relevant protocols, and this embodiment does not impose any limitations.

[0150] In one embodiment, after the terminal receives the first message from the first RAT, the terminal further includes: sending a second message to the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

[0151] The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

[0152] The second message can specifically be a message used to initiate a service request process; for example, the second message can be a service request message or a service request.

[0153] In one example, the first core network device is a control plane network element on the core network side that receives the second message.

[0154] If the terminal performs multi-access connection management at the RAT level, the second message may carry at least one of the following: the NAS identifier for paging corresponding to the second RAT, or the identifier of the session that the terminal recognizes is allowed to be activated on the second RAT.

[0155] If the terminal manages multiple access connections at the connection level, the second message may carry at least one of the following: the NAS identifier for paging corresponding to the second RAT, and the identifier of the session that the terminal recognizes is allowed to be activated on the second RAT. Specifically, the NAS identifier for paging corresponding to the second RAT is the NAS identifier for paging corresponding to the second logical connection; the identifier of the session that the terminal recognizes is the identifier of the session that the terminal recognizes is allowed to be activated on the second logical connection.

[0156] The processing of the second access network device may include: the second access network device receiving a second message from the terminal; the second access network device sending the second message to the first core network device. After the first core network device sends the first message to the first RAT, the processing may also include: the first core network device receiving the second message sent by the terminal through the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

[0157] Optionally, the second RAT is the RAT corresponding to the downlink message to be transmitted, and the network side manages multiple access connections for the terminal at the RAT granularity. The second message can be used to indicate that the terminal requests to establish a NAS connection with the first core network device through the second access network device under the second RAT. This second message can carry the NAS identifier corresponding to the second RAT for paging.

[0158] After receiving the second message, the first core network device can establish a NAS connection under the second RAT (referred to as the second NAS connection) with the terminal through the second access network device, and after the establishment of the second NAS connection is completed, send downlink messages (downlink NAS messages) to the terminal through the second NAS connection.

[0159] The first message may also carry a first timer. If the duration of the first timer is the maximum duration for the terminal to initiate the establishment of a NAS connection in the second RAT, then the terminal needs to send the second message within the duration of the first timer; if the duration of the first timer is the maximum duration for the terminal to complete the establishment of a NAS connection in the second RAT, then the terminal needs to send the second message and complete the establishment of a second NAS connection under the second RAT within the duration of the first timer.

[0160] Optionally, the second logical connection is the connection corresponding to the downlink message to be transmitted, and the network side manages multiple access connections for the terminal at the connection granularity. The second message can be used to indicate that the terminal requests to establish a NAS connection with the first core network device through the second access network device corresponding to the second logical connection. This second message can carry a NAS identifier for paging corresponding to the second logical connection.

[0161] After receiving the second message, the first core network device can establish a NAS connection (referred to as the second NAS connection) corresponding to the second logical connection with the terminal through the second access network device. After the establishment of the second NAS connection is completed, a downlink message (downlink NAS message) is sent to the terminal through the second NAS connection. It should be noted that the first message may also carry a first timer. The relevant explanation regarding the relationship between the timing duration of the first timer and the sending of the second message or the establishment of the second NAS connection is similar to the previous example and will not be repeated here.

[0162] Optionally, the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, and the network side manages multiple access connections for the terminal at the RAT granularity. The second message can be used to indicate that the terminal requests to establish a NAS connection with the first core network device through the second access network device under the second RAT; and the second message is also used to establish user plane resources corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session. The second message carries the NAS identifier for paging corresponding to the second RAT and the identifier of the session that the terminal recognizes is allowed to be activated on the second RAT.

[0163] After receiving the second message, the first core network device can establish a second NAS connection under the second RAT with the terminal through the second access network device. After the establishment of the second NAS connection is completed, the first core network device determines whether the first session with downlink data to be transmitted is included in the sessions identified by the terminal that are allowed to be activated on the second RAT based on the identifier of the sessions identified by the terminal. If so, the first session with UP connection is activated and the session management network element is requested to establish user plane resources for the first session.

[0164] Additionally, the method may include: if the first core network device determines that the sessions identified by the terminal as permitted to be active on the second RAT do not include a first session containing downlink data to be transmitted, the first core network device may notify the session management element that the terminal is unreachable on the second RAT. The processing after the first core network device notifies the session management element that the terminal is unreachable on the current second RAT is not limited in this embodiment.

[0165] It should be noted that the first message may also carry a first timer. In this case, if the duration of the first timer is the maximum duration for the terminal to initiate the establishment of user plane resources in the second RAT, the terminal needs to send the second message within the duration of the first timer. If the duration of the first timer is the maximum duration for the terminal to complete the establishment of user plane resources in the second RAT, the terminal needs to send the second message and complete the establishment of user plane resources under the second RAT within the duration of the first timer. In addition, the first core network device can also start timing after sending the first message. If the second message is not received within the duration of the first timer (or a specified duration longer than the duration of the first timer), or if it is determined that the establishment of the second NAS connection has not been completed, or if it is determined that the establishment of user plane resources has not been completed, the first core network device determines to further page the terminal according to relevant policies. These relevant policies can be configured according to actual conditions, and the specified duration can also be configured according to actual conditions. This embodiment does not limit this.

[0166] Optionally, the second logical connection is a connection corresponding to a first session with downlink data to be transmitted, and the network side manages multiple access connections for the terminal at the connection level. The second message can be used to indicate that the terminal requests to establish a NAS connection corresponding to the second connection with the first core network device through the second access network device corresponding to the second logical connection; and the second message is also used to establish user plane resources corresponding to the second logical connection for transmitting downlink data to be transmitted in the first session. The second message carries a NAS identifier for paging corresponding to the second logical connection and an identifier of the session that the terminal recognizes is allowed to be active on the second logical connection.

[0167] After receiving the second message, the first core network device can establish a second NAS connection corresponding to the second logical connection with the terminal through the second access network device. After the establishment of the second NAS connection is completed, the first core network device determines whether the first session that is allowed to be activated on the second logical connection identified by the terminal includes a first session with downlink data to be transmitted, based on the identifier of the session that is allowed to be activated on the second logical connection identified by the terminal. If it does, the first session that is activated to activate the UP connection is determined, and the session management network element is requested to establish user plane resources for the first session.

[0168] Additionally, the method may include: if the first core network device determines that the sessions identified by the terminal as permitted to be active on the second logical connection do not include a first session containing downlink data to be transmitted, the first core network device may notify the session management network element that the terminal is unreachable on the second connection of the second RAT. The processing after the first core network device notifies the session management network element that the terminal is unreachable on the current second logical connection is not limited in this embodiment.

[0169] It should be noted that the first message may also carry a first timer. The explanation of the timing duration of the first timer and its relationship with sending the second message or establishing the relationship between user plane resources is similar to the previous example and will not be repeated here.

[0170] In one example, the second message is received by a second core network device, and the second core network device is different from the first core network device.

[0171] The processing of the second access network device may include: the second access network device receiving a second message from the terminal, wherein the second message is used to establish a NAS connection in the second RAT; the second access network device sending the second message to the second core network device. The processing of the second core network device may include: the second core network device receiving the second message sent by the terminal through the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

[0172] In this example, the content that the second message may carry is the same as in the previous example, and the related processing of the second core network device is similar to that of the first core network device, so it will not be described again. The only difference from the previous example is that the first core network device can also send the first timer to the second core network device. The second core network device can start timing when it receives the first timer and detect whether the second message has been received within the timeout period of the first timer, or whether the establishment of the second NAS connection has been completed, or whether the establishment of user plane resources has been completed, etc., without limiting or exhaustively listing them here. In addition, if the second core network device does not receive the second message within the timeout period of the first timer, or determines that the establishment of the second NAS connection has not been completed, or determines that the establishment of user plane resources has not been completed, then the second core network device determines to further page the terminal according to the relevant policy. The relevant policy can be configured according to the actual situation, and this embodiment does not limit it.

[0173] Referring to Figure 9, taking the first core network device as MM, the terminal as UE, the first access network device as 5G RAN, and the second access network device as 6G RAN as an example, the communication method provided in this embodiment will be illustrated by way of example:

[0174] Step 901: The MM sends a paging message (i.e., a second paging message) to the UE through the 5G RAN corresponding to the first RAT. This paging message may include the GUTI and the type information of the second RAT (such as the RAT type information corresponding to the 6G RAN).

[0175] If the network needs to send downlink signaling messages to an idle UE on a certain RAT (such as the second RAT) or needs to send data on a certain RAT (such as the second RAT), and the MM cannot page the UE through a certain RAT (such as the second RAT) or connection (such as a second logical connection established on the access network device corresponding to the second RAT), then the MM can page the UE on the first RAT (i.e., the RAT corresponding to the 5G RAN) (i.e., execute step 901). The first RAT can be determined based on the UE's current location, or based on the RAT corresponding to the TAI of the last network access, or based on the RAT of the last access network device.

[0176] The reason why the MM cannot page the UE through a certain RAT (such as the second RAT) or connection (second logical connection) may be: pager failed on the second RAT or the second logical connection; or the RAT corresponding to the TAI where the UE was last camped was not the second RAT on which the network needs to send downlink signaling or data; or the NAS connection established between the access network device corresponding to the TAI where the UE was last camped and the network was not the connection on which the network needs to send downlink signaling; or the current location of the UE is not within the coverage area of ​​the access network device corresponding to the second RAT in the registration area; or the UE is not within the dedicated registration area allocated by the MM for the second RAT.

[0177] Specifically, paging messages mainly include the first message and a list of registered areas.

[0178] The Registration Area list refers to the registration areas corresponding to one or more RATs if the MM allocates a dedicated Registration Area (RA) for each RAT during the initial registration process. Each RAT's registration area consists of one or more Registration Areas (TAIs) for that RAT. Alternatively, the registration area list may only include the registration area corresponding to the first RAT.

[0179] The first message includes at least one of the following:

[0180] GUTI, which is the UE identifier (NAS identifier for paging) assigned by MM to the first RAT (or the first logical connection). It should be noted that this GUTI can also be replaced by 5G-S-TMSI, without limitation or exhaustive list here;

[0181] RAT type (i.e., type information of the second RAT), for example, when the terminal performs multi-access connection management based on RAT, the second RAT is the RAT associated with the first PDU session, that is, the downlink data packet needs to be sent to the UE on the RAT; or the second RAT is the RAT corresponding to the connection with the downlink NAS message to be transmitted.

[0182] The connection ID (i.e. the connection identifier of the second logical connection) is used to indicate whether there is a downlink NAS message that needs to be sent to the UE on the NAS connection corresponding to the second logical connection, or whether there is a downlink data packet that needs to be sent to the UE on the user plane resources (N3 tunnel and DRB) corresponding to the second logical connection when the terminal performs multi-access connection management based on the connection.

[0183] In step 902, the 5G RAN sends a paging message (i.e., the first paging message) to the UE. This paging message may include GUTI and type information of the second RAT (such as the RAT type information corresponding to the 6G RAN). Specifically, this paging message may carry a first message, the relevant description of which is the same as in step 901 and will not be repeated here.

[0184] Step 903: After receiving the paging message, the UE initiates a service request (i.e., the second message) to the 6G RAN corresponding to the second RAT.

[0185] Step 904: The 6G RAN forwards the service request to the MM via the N2 message.

[0186] The service request messages in steps 903 and 904 are used to establish a second NAS connection with the MM on the second RAT (or the second logical connection). The parameters carried in this service request message are the same as in the previous embodiments and will not be described again.

[0187] By adopting the above scheme, when the first core network device cannot page the terminal through the second RAT or the second logical connection, the first core network device can page the terminal through other RATs, such as the first RAT, to trigger the terminal to establish a NAS connection on the second RAT. This avoids paging terminal failure due to the terminal being outside the coverage area of ​​the second access network corresponding to the second RAT or the second logical connection on which the network needs to send downlink signaling or data, thereby increasing the probability of the terminal responding to paging. The scheme provided in this embodiment is particularly applicable to scenarios where paging terminal failure occurs on the second RAT or the second logical connection. For example, since the LEO satellite has already flown over the UE, the network cannot page the UE on the NR (LEO) satellite (second RAT), but can page the UE through NR (GEO) or NR (first RAT) and notify the UE to wait for the LEO satellite to fly over it again to provide coverage before requesting to establish a connection with NR (LEO).

[0188] Referring to Figure 10, taking the first core network device as MM, the terminal as UE, the first access network device as 5G RAN, and the second access network device as 6G RAN as an example, another exemplary description of the communication method provided in this embodiment is given:

[0189] Step 1001: The MM sends a NAS notification message to the UE through the 5G RAN corresponding to the first RAT. This NAS notification message may carry the type information of the second RAT (such as the RAT type information corresponding to the 6G RAN).

[0190] If the network needs to send downlink signaling messages to the UE on a certain RAT (such as the second RAT) or needs to send data on a certain RAT (such as the second RAT), and the MM cannot page the UE through a certain RAT (such as the second RAT) or connection (such as the second logical connection), the MM can notify the UE (i.e., execute step 1001) on the first RAT (i.e., the RAT corresponding to the 5G RAN) which is in the connection management connection state. This NAS notification message is used to notify the UE to access the core network on the second RAT (or the second logical connection). For example, the UE is notified on the TN connection (the first logical connection corresponding to the 5G NR (i.e., the first RAT) to access the core network through NTN access (e.g., NR(GEO), NR(LEO), etc., i.e., the second RAT).

[0191] Specifically, the NAS notification message may carry the first message from the aforementioned embodiments. This first message contains at least one of the following information:

[0192] RAT type (i.e., type information of the second RAT), for example, when the terminal performs multiple access connection management based on RAT, the RAT type is used to instruct the UE and MM to establish a NAS connection on the second RAT to receive the corresponding downlink NAS signaling, or to establish user plane resources of the first PDU session corresponding to the second RAT to receive downlink data.

[0193] The connection ID (i.e., the connection identifier of the second logical connection) is used to instruct the UE and MM to establish a corresponding NAS connection when the terminal performs multi-access connection management based on the connection.

[0194] Notification timer (first timer): Indicates that the UE needs to establish a NAS connection with the MM on the specified RAT or connection within this time.

[0195] When the MM sends this message, it will set a Notification timer (which can be slightly longer than the first timer sent to the UE). The MM monitors the paging process through the timer. If it does not receive a response from the UE to the paging request, it can perform further paging according to any applicable paging strategy in other embodiments, which is not limited here.

[0196] Steps 1002 to 1003 are the same as steps 903 to 904 in the previous example, and will not be repeated.

[0197] By adopting the above scheme, when the first core network device cannot page the terminal through the second RAT or the second logical connection, for example, after the second RAT or the second logical connection fails to page the UE, it can send a NAS notification message to the terminal through the first RAT (or the first logical connection) that is in a connected state. This allows the terminal to successfully establish a NAS connection with the network and / or activate a PDU session on the second RAT designated by the network, thereby receiving signaling messages and / or service data sent by the network on the second RAT more quickly. This avoids the network from caching the signaling messages and / or service data to be sent for a long time due to the terminal's failure to page on the second RAT, which would excessively occupy network storage resources.

[0198] In some possible implementations, triggering the terminal to perform operations related to the second RAT may include triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT. That is, the first message is used to trigger the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

[0199] The triggering reason for the first core network device to send the first message may include: the terminal's connection under the second RAT is disconnected, and the network side determines to rebuild the second session corresponding to the terminal under the second RAT under the first RAT to ensure service continuity. The number of such second sessions can be one or more. For example, the second session corresponding to the terminal under the second RAT that needs to be rebuilt can be a session under the second RAT with pending downlink data transmission, or it can be any one or more sessions under the second RAT. For instance, when a satellite (satellite access is an example of the second RAT in this embodiment) is about to leave the terminal and cannot provide service, the terminal can be paged on a terrestrial network (NR or 6G RAT, i.e., the first RAT in this embodiment), instructing the terminal to re-establish a connection with the network from the RAT (first RAT) of the terrestrial network and re-establish the session previously carried on the satellite (i.e., the second session) on the terrestrial network, thereby allowing the terminal to continue receiving service data previously sent to the UE through the NTN network to ensure service continuity.

[0200] After receiving the first message in the first RAT, the terminal further includes one of the following: the terminal sends a service request to the first access network device corresponding to the first RAT, wherein the service request carries a third message, the third message being used to request the reconstruction of the second session corresponding to the second RAT in the first RAT; the terminal sends a session modification request to the first core network device through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

[0201] After the first access network device sends the first message to the terminal, the method further includes: the first access network device receiving a service request from the terminal, wherein the service request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; and the first access network device sending the service request to the first core network device.

[0202] Alternatively, after the first access network device sends the first message to the terminal, the method further includes: the first access network device receiving a session modification request from the terminal, wherein the session modification request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; and the first access network device sending the session modification request to the first core network device.

[0203] After the first core network device sends the first message in the first RAT, it further includes one of the following: the first core network device receives a service request through the first access network device corresponding to the first RAT, wherein the service request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; the first core network device receives a session modification request from the terminal through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

[0204] In one embodiment, if the terminal is in an idle state on the first RAT, the first core network device can trigger the terminal to rebuild the second session corresponding to the second RAT on the first RAT by paging.

[0205] The first core network device can carry the first message through the second paging message. Correspondingly, the terminal receives the first message carried by the first paging message from the first access network device. The transmission of the second paging message and the first paging message is the same as described in the previous embodiments, that is, both the second paging message and the first paging message carry the first message. The second paging message also carries the registration area list, which will not be elaborated here.

[0206] Unlike the previous embodiments, in this embodiment, in addition to carrying the NAS identifier for paging corresponding to the first RAT, the first message may carry at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the second session that needs to be rebuilt; the identifier of the second session; a second timer, wherein the duration of the second timer is the maximum duration for the terminal to initiate or complete the reconstruction of the second session corresponding to the second RAT on the first RAT; and an indication to rebuild the second session corresponding to the second RAT on the first RAT.

[0207] The second RAT can be a RAT type associated with a PDU session, and the PDU session can be the session that needs to be rebuilt under the second RAT (the second session).

[0208] Optionally, the first message may carry the NAS identifier for paging corresponding to the first RAT and the type information of the second RAT. In this case, the first message may not carry an instruction to rebuild the second session corresponding to the second RAT on the first RAT, nor may it carry the identifier of the second session. Instead, the content carried by the first message implicitly indicates that the session corresponding to the second RAT needs to be rebuilt on the current first RAT.

[0209] Optionally, the first message may carry the NAS identifier for paging corresponding to the first RAT, the type information of the second RAT, and the identifier of the second session. In this case, the first message may not carry an instruction to rebuild the second session corresponding to the second RAT on the first RAT, but may implicitly indicate through the content carried by the first message that the second session corresponding to the second RAT needs to be rebuilt on the current first RAT.

[0210] Optionally, the first message may carry the NAS identifier for paging corresponding to the first RAT, the type information of the second RAT, the identifier of the second session, and an indication to rebuild the second session corresponding to the second RAT on the first RAT. In this case, the content carried by the first message can indicate that the second session corresponding to the second RAT needs to be rebuilt on the current first RAT.

[0211] After the terminal receives the first message from the first RAT, the process further includes: the terminal sending a service request carrying a third message to the first access network device corresponding to the first RAT. The processing of the first access network device includes: the first access network device receiving the service request from the terminal; the first access network device sending the service request to the first core network device. The processing of the first core network device may include: the first core network device receiving the service request from the first access network device.

[0212] The third message carries at least one of the following: an identifier of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT; and a NAS identifier for paging corresponding to the first RAT. Preferably, the third message may carry an identifier of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT, and a NAS identifier for paging corresponding to the first RAT.

[0213] The identifier of one or more sessions corresponding to the second RAT that the terminal allows to be re-established on the first RAT can be an identifier used to indicate that the terminal allows the re-establishment of one or more sessions previously established on the second RAT on the first RAT corresponding to the TAI that received the paging message. Specifically, the terminal can determine the identifier of the session corresponding to the second RAT that can be re-established on the first RAT corresponding to the first access network device that sent the paging message, based on the type information of the second RAT. In this example, regardless of whether the first message carries which session(s) under the second RAT need to be re-established on the first RAT (i.e., regardless of whether the first message carries the identifier of the second session), the terminal can determine which session(s) corresponding to the second RAT it allows to be re-established on the first RAT based on the relevant information of all sessions corresponding to the second RAT stored locally.

[0214] Accordingly, after receiving the third message, the first core network device may include the following processing: the first core network device extracts from the third message the identifiers of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT; if the identifiers of the one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT include the second session corresponding to the second RAT that needs to be rebuilt, the first core network device may request the session management network element to establish user plane resources for the second session. This embodiment does not limit the related processing of the session management network establishing user plane resources corresponding to the first RAT to migrate the second session.

[0215] Additionally, if the identifiers of one or more sessions corresponding to the second RAT that the terminal is allowed to rebuild on the first RAT do not include the second session corresponding to the second RAT that needs to be rebuilt, the first core network device may notify the session management network element that the terminal is unreachable on the current first RAT.

[0216] Optionally, in addition to carrying at least one of the identifiers of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT, and the NAS identifier for paging corresponding to the first RAT, the third message may also carry the identifiers of one or more sessions that need to be activated. These one or more sessions that need to be activated may be one or more sessions that were deactivated by the terminal on the first RAT and need to be reactivated when the third message (i.e., service request) is sent.

[0217] Accordingly, after receiving the third message, the first core network device may include the following processing: the first core network device extracts the identifiers of one or more sessions that need to be activated from the third message; the first core network device determines, based on at least one of the UE subscription information, network configuration, mobility restrictions, etc., one or more sessions among the one or more sessions that need to be activated that should have user plane connections activated, and requests the session management network element to establish user plane resources for the one or more sessions that should have user plane connections activated. This embodiment does not limit the specific processing method by which the first core network device determines, based on at least one of the UE subscription information, network configuration, mobility restrictions, etc., one or more sessions among the one or more sessions that need to be activated that should have user plane connections activated. This embodiment also does not limit the related processing of the session management network establishing user plane resources for the one or more sessions that should have user plane connections activated.

[0218] In one embodiment, if the terminal is in a connected state on the first RAT, the first core network device can trigger the terminal to rebuild the second session corresponding to the second RAT on the first RAT through a NAS notification message.

[0219] The first core network device sends a first message in the first RAT, including: the first core network device sends a NAS notification message to the terminal through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message. The terminal receives the first message in the first RAT, including: the terminal receives the NAS notification message from the first core network device through the first access network device corresponding to the first RAT. The processing of the first access network device may include: the first access network device receiving the NAS notification message from the first core network device; the first access network device sending the NAS notification message to the terminal.

[0220] The first message can carry content similar to that in the previous embodiments. The difference is that the first message in this embodiment may not carry the NAS identifier for paging corresponding to the first RAT, which will not be elaborated here.

[0221] Optionally, the first message may carry the type information of the second RAT and the second timer. In this case, the terminal can start timing after receiving the first message. Correspondingly, the first core network device can start timing after sending the first message.

[0222] Furthermore, within the duration of the second timer, the terminal needs to send a third message or complete the reconstruction of the second session. The first core network device can detect whether it has received a third message (such as a session modification request carrying a third message) or completed the reconstruction of the second session within the duration of the second timer. If it has not received a third message or completed the reconstruction of the second session, the first core network device can determine that the terminal is unreachable on the first RAT, and can then perform paging on other RATs or send NAS notification messages to the terminal. Here, the processing of the terminal after the first RAT becomes unreachable is not limited or exhaustively listed.

[0223] Optionally, in addition to carrying the type information of the second RAT and the second timer, the first message may also carry at least one of the following: the identifier of the second session and an instruction to rebuild the second session corresponding to the second RAT on the first RAT. This embodiment does not limit or exhaust all possibilities of the content that the first message may carry.

[0224] After the terminal receives the first message from the first RAT, the method further includes: the terminal sending a session modification request carrying the third message to the first core network device through the first access network device corresponding to the first RAT. The processing of the first access network device includes: the first access network device receiving the session modification request from the terminal, and the first access network device sending the session modification request to the first core network device. The processing of the first core network device may include: the first core network device receiving the session modification request from the terminal through the first access network device. In this embodiment, the description of the specific content carried by the third message and the related processing of the first core network device after receiving the third message are the same as in the previous embodiments, and therefore will not be repeated.

[0225] Referring to Figure 11, taking the first core network device as MM, the terminal as UE, the first RAT as 5G RAT, and the second RAT as 6G RAT as an example, the communication method provided in this embodiment will be described exemplarily as follows:

[0226] Step 1101: The MM sends a paging message (i.e., a second paging message) to the UE through the 5G RAN (first access network device) corresponding to the first RAT. This paging message may include the type information of the RAT corresponding to the GUTI and 6G RAN (type information of the second RAT).

[0227] For example, when the UE loses its connection with the network on a certain RAT (e.g., the NR (LEO) of an NTN, i.e., the second RAT), the MM can page the UE on the first access network device corresponding to another RAT* (e.g., the NR of a TN) (such as the first RAT) and instruct the UE to re-establish the session associated with the RAT on the RAT*. This first access network device can be any access network device in the registration area corresponding to the first RAT, or the access network device corresponding to the TAI last accessed by the terminal, or the access network device corresponding to the cell last accessed by the terminal.

[0228] Specifically, paging messages mainly include the first message and a list of registered areas.

[0229] Specifically, the registration area list may include RAT*-specific RA and / or TAI and / or cell ID, which are used to indicate to the first access network device that it needs to page the UE in the RA corresponding to the first RAT, or in the TAI accessed by the UE in the first RAT, or in the cell accessed by the UE in the first RAT, thereby assisting the first access network device in determining the paging area.

[0230] The first message includes at least one of the following:

[0231] GUTI, this GUTI is the NAS identifier assigned by MM to the first RAT for paging UE;

[0232] RAT type (i.e., type information of the second RAT) (or RAT type associated to PDU session) is used to indicate the RAT type (type information of the second RAT) associated with the PDU session that needs to be re-established.

[0233] In step 1102, the 5G RAN sends a paging message (i.e., the first paging message) to the UE. This paging message may include the GUTI and the type information of the second RAT (the type information of the RAT corresponding to the 6G RAN). Specifically, this paging message may carry a first message, the relevant description of which is the same as in step 1101 and will not be repeated here.

[0234] Step 1103: After receiving the paging message, the UE initiates a service request to the 5G RAN (first access network device) corresponding to the first RAT. The service request carries a third message.

[0235] Specifically, the UE initiates a service request on the first access network device that sends the paging message, and confirms, based on the RAT type associated to PDU session carried in the paging message, the PDU session corresponding to the second RAT type (e.g., NR(LEO)) that can be re-established on the first RAT (e.g., NR) corresponding to the access network device that sent the paging message. The third message carried in the service request indicates the identifier of the PDU session that the UE allows to be re-established on the first RAT (NR) and the identifier of the PDU session that the UE needs to activate on this first RAT (NR).

[0236] The service request carries at least one of the following parameters in the third message:

[0237] One or more PDU sessions associated with a RAT (RAT corresponding to 6G RAN) (identifiers of one or more sessions corresponding to the second RAT that can be re-established on the first RAT) are used to indicate that the UE allows the re-establishment of one or more PDU sessions previously established on the second RAT (RAT corresponding to 6G RAN) on the first RAT (NR) corresponding to the TAI on which the paging message is received.

[0238] One or more PDU sessions that need to be activated, such as PDU sessions that were previously deactivated on the first RAT(NR), can be reactivated through a service request;

[0239] UE identifier, 5G-S-TMSI (i.e., the identifier used for paging corresponding to the first RAT).

[0240] In step 1104, the access network device sends the service request to the MM via an N2 message. Upon receiving the service request, the MM can determine the PDU session for which the UP connection should be activated based on at least one of the following: UE subscription information, network configuration, mobility restrictions, etc., and request the session management network element to establish user plane resources for the PDU session. Additionally, if the MM finds that the PDU session indicated in the service request does not contain a PDU session that needs to send downlink data, it can notify the session management network element that the UE is unreachable on the first RAT (or NAS connection).

[0241] Referring to Figure 12, taking the first core network device as MM, the terminal as UE, the first RAT as 5G RAT, and the second RAT as 6G RAT as an example, another exemplary description of the communication method provided in this embodiment will be given:

[0242] In step 1201, the MM can send a NAS notification message to the UE through the NAS connection corresponding to the first RAT (5G RAN) in the connected state. This NAS notification message can carry the first message in the aforementioned embodiments, such as carrying the type information of the second RAT (e.g., the type information of the 6G RAN RAT), etc., which will not be elaborated here.

[0243] For example, when the UE loses its connection with the network on the second RAT (e.g., the RAT corresponding to 6G RAN), the MM can send a NAS notification message to the UE on another connected first RAT (e.g., the RAT corresponding to 5G RAN) to instruct the UE to re-establish the session associated with 6G RAN on 5G RAN.

[0244] In step 1202, after receiving the NAS notification message, the UE, based on the second RAT type indicated in the NAS notification message being 6G RAN, re-establishes the PDU session associated with the 6G RAN on the 5G RAN. The UE can initiate a PDU session modification procedure to the MM through the 5G RAN (the first access network device corresponding to the first RAT). The session modification request in this session modification procedure can carry the third message of the aforementioned embodiment, such as at least one of the following information: UE identification information (which can be GUTI, SUPI, etc., not limited in this example); one or more PDU session identifiers associated with the RAT (second RAT) corresponding to the 6G RAN, used to indicate the PDU session that the MM can access on the RAT (first RAT) corresponding to the 5G RAN.

[0245] After receiving the session modification request, the MM can determine the PDU session corresponding to the 6G RAN that can be established on the 5G RAN based on the UE's mobility restrictions (including RAT restrictions, service area restrictions, etc.), and initiate a session modification procedure to the corresponding session management network element to establish user plane resources for the PDU session on the 5G RAN.

[0246] The above-described solution provided in this embodiment is particularly applicable to scenarios where, when a certain RAT (second RAT) becomes unavailable, the associated PDU session is migrated to another available RAT (such as the first RAT) to ensure service continuity. For example, when a UE leaves the coverage area of ​​an access network device deployed on a satellite, while maintaining a connection with an access device in the terrestrial network, the mobility management network element can notify the UE to re-establish the session previously carried on the satellite on the terrestrial network, thereby ensuring that the UE can continue to receive service data previously sent via satellite, thus guaranteeing user experience.

[0247] In some possible implementations, before the terminal receives the first message in the first RAT, it may further include: the terminal sending a fourth message to the first core network device through the first access network device corresponding to the first RAT, wherein the fourth message carries first indication information, the first indication information being used to indicate independent multi-access connection management for the terminal under different RATs.

[0248] Before the first access network device receives the first message from the first core network device, the method further includes: the first access network device sending a fourth message from the terminal to the first core network device, wherein the fourth message carries first indication information, the first indication information being used to indicate independent multi-access connection management for the terminal under different RATs.

[0249] Before the first core network device sends the first message in the first RAT, the method further includes: the first core network device receiving a fourth message from the terminal through the first access network device corresponding to the first RAT, wherein the fourth message carries first indication information, which is used to indicate that the terminal is managed independently under different RATs.

[0250] Optionally, the first indication information may include the terminal's capability information. This capability information may include at least the terminal's multi-access capability information and / or information regarding its ability to perform independent connection management based on RAT. The terminal's multi-access capability information can be used to indicate that the terminal possesses multi-access capabilities. In other words, the terminal can use its own capability information as the first indication information to instruct the network side (such as the first core network device) to perform multi-access connection management on the terminal.

[0251] Optionally, the first indication information can be newly added indication information. For example, the newly added indication information can be directly carried in the fourth message sent by the terminal to instruct the network side (such as the first core network device on the core network side) to perform multi-access connection management on the terminal.

[0252] In some possible implementations, multi-access connection management for terminals is performed at the RAT level.

[0253] In this embodiment, the first indication information is at the RAT granularity, that is, the first indication information can be used to request or instruct the first core network device to perform RAT-based connection management (or multi-access connection management) on the terminal, or to request or instruct the first core network device to perform mutually independent multi-access connection management on the terminal based on different RATs.

[0254] Specifically, the independent multi-access connection management of the terminal under different RATs includes at least one of the following: managing the connection status of the terminal under different RATs; and assigning different NAS identifiers for paging to the terminal corresponding to different RATs.

[0255] Managing the connection status of the terminal independently under different RATs can refer to managing the connection status of multiple NAS connections that the terminal can establish under multiple RATs independently at the RAT level. In other words, maintaining or managing the connection status under each RAT at the RAT level.

[0256] The connection state corresponding to any RAT can include either the idle state or the connected state of the RAT.

[0257] Assigning different NAS identifiers for paging to the terminal corresponding to different RATs can mean assigning different NAS identifiers for paging to the terminal at the RAT level.

[0258] It should be noted that a terminal can establish multiple connections under multiple RATs. These connections can refer to a general connection or specifically to a NAS connection under a given connection. Furthermore, the multiple connections a terminal can establish under multiple RATs can include: one or more connections under each of one or more RATs that the terminal has already established, and / or one or more connections under each of one or more RATs that the terminal has not yet established but may establish. In other words, when the terminal issues the first indication information, it may not have established multiple connections under multiple RATs. However, this first indication information allows the first core network device to determine that if the terminal establishes more connections under more RATs in the future, it will need to manage independent multi-access connections based on different RATs at the RAT level.

[0259] Optionally, the independent multi-access connection management of the terminal under different RATs includes assigning different NAS identifiers for paging to the terminal corresponding to different RATs.

[0260] Optionally, the step of independently managing multiple access connections for the terminal under different RATs includes managing the connection status of the terminal independently under different RATs and assigning different NAS identifiers for paging to the terminal corresponding to different RATs.

[0261] In one embodiment, after the first core network device receives a fourth message from the terminal through the first access network device corresponding to the first RAT, the method further includes: the first core network device sending a fifth message to the terminal through the first access network device, wherein the fifth message carries second indication information, the second indication information being used to instruct the first core network device to support independent multi-access connection management of the terminal under different RATs.

[0262] After the first access network device sends the fourth message from the terminal to the first core network device, the method further includes: the first access network device sending a fifth message from the first core network device to the terminal, wherein the fifth message carries second indication information, the second indication information being used to indicate that the first core network device supports independent multi-access connection management for the terminal under different RATs.

[0263] After the terminal sends a fourth message to the first core network device through the first access network device corresponding to the first RAT, the method further includes: the terminal receiving a fifth message from the first core network device through the first access network device, wherein the fifth message carries second indication information, the second indication information being used to instruct the first core network device to support independent multi-access connection management for the terminal under different RATs.

[0264] Specifically, the first core network device sending a fifth message to the terminal through the first access network device may include: the first core network device determining whether it supports RAT-based connection management of the terminal based on at least one of the following: UE subscription information, local configuration, and network capabilities; if the first core network device determines that it supports independent multi-access connection management of the terminal under different RATs (or supports RAT-based multi-access connection management of the terminal), the first core network device sends a fifth message carrying second indication information to the terminal through the first access network device.

[0265] The terminal's subscription information can be obtained from the UDM; the local configuration may include whether the first core network device itself can provide RAT-based connection management to the terminal; the network capabilities may include the capabilities of the network where the first core network device is located (e.g., the core network side), which may include whether it supports RAT-based connection management, etc. The network capabilities are not limited or exhaustively listed here. This embodiment does not limit the specific processing method by which the first core network device determines whether it supports RAT-based connection management to the terminal based on at least one of the UE's subscription information, local configuration, and network capabilities.

[0266] Additionally, it may include: if the first core network device determines that it does not support independent multi-access connection management for the terminal under different RATs (or does not support RAT-based multi-access connection management for the terminal), the first core network device sends a fifth message to the terminal through the first access network device to indicate that it does not support independent multi-access connection management for the terminal under different RATs.

[0267] In one embodiment, the fourth message can be a registration message or a registration request, meaning it can be used to request registration under the first RAT. Specifically, the fourth message is used for the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device. Correspondingly, the fifth message can carry the NAS identifier for paging corresponding to the first RAT.

[0268] In one example, the terminal has not performed registration under any other RAT before performing registration under the first RAT (i.e., sending the fourth message).

[0269] On the first core network device side, the processing after determining that independent multi-access connection management of the terminal under different RATs is supported may further include: the first core network device determining the first RAT; the first core network device determining whether to perform registration update or to perform registration under the first RAT; if it is determined that registration is performed under the first RAT, the first core network device assigns a NAS identifier for paging corresponding to the first RAT to the terminal.

[0270] The first core network device can determine the first RAT in the following ways: if the fourth message carries the type information of the first RAT, the first RAT is determined directly; if the fourth message does not carry the type information of the first RAT, the first RAT is determined based on the relevant information of the first access network device. Here, the first RAT can be any one of multiple RATs.

[0271] The relevant information of the first access network device may include at least one of the following: the identifier of the first access network device, the TAI associated with the first access network device, etc. The TAI associated with the first access network device may be sent to the first core network device when the first access network device forwards the fourth message, or it may be pre-configured on the side of the first core network device. This embodiment does not limit or exhaustively list them.

[0272] Optionally, the fourth message may also carry the registration type corresponding to the fourth message, which can be initial registration or registration. The first core network device's determination of whether to perform a registration update or registration under the first RAT may include: if the registration type carried in the fourth message is initial registration or registration, the first core network device determines to perform registration under the first RAT; if the registration type carried in the fourth message is registration update (such as mobility registration update or periodic registration), the first core network device determines to perform a registration update under the first RAT.

[0273] Optionally, the fourth message may not carry the registration type. The first core network device's determination of whether to perform a registration update or registration under the first RAT may include: if the first core network device finds the terminal's context locally and the terminal's context includes the context corresponding to the first RAT, the first core network device determines to perform a registration update under the first RAT; if the first core network device does not find the terminal's context locally and / or the terminal's context does not include the context corresponding to the first RAT, the first core network device determines to perform registration under the first RAT.

[0274] The specific processing method by which the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal is not limited in this embodiment. After the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal, it can send the NAS identifier for paging corresponding to the first RAT to the terminal in a fifth message. This fifth message can also be used to indicate that the terminal has successfully established a first NAS connection under the first RAT between the first access network device and the first core network device.

[0275] The processing after the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal may further include: the first core network device adding the NAS identifier for paging corresponding to the first RAT to the terminal's context.

[0276] Specifically, the first core network device can store or maintain the terminal's context. For example, if the first core network device is an AMF (Application Management Provider), the AMF can store the terminal's context locally. The terminal's context stored by the AMF can be called the UE Context in AMF, or the UE access and mobility context. The terminal's context can include the context corresponding to each RAT (Rate Access Terminal). This context can also be called the context for each RAT type level within the UE access and mobility context. The first core network device adds the NAS (Non-Standard Access Attachment) identifier for paging corresponding to the first RAT to the terminal's context. This can be achieved by the first core network device adding the type information of the first RAT and the NAS identifier for paging corresponding to the first RAT to the context corresponding to that first RAT in the terminal's context.

[0277] The processing by the first core network device may further include: the first core network device adding the connection state corresponding to the first RAT to the context of the terminal. The connection state corresponding to the first RAT refers to the connection state of the terminal corresponding to the first RAT, which may include one of the following: connection management idle state (referred to as idle state) and connection management connected state (referred to as connected state).

[0278] For example, if the terminal sends the fourth message for registration, this fourth message is used to establish a first NAS connection under the first RAT between the terminal and the first core network device through the first access network device. When the first core network device determines that the terminal has completed registration, it can be determined that the first NAS connection under the first RAT between the terminal and the first core network device through the first access network device has been established. Furthermore, the first core network device can determine that in the context of the terminal, the context corresponding to the first RAT may include the terminal's connection state in the first RAT being a connected state.

[0279] Referring to Table 1, taking AMF as the first core network device and RAT-1 as the first RAT as an example, the UE context in AMF on the AMF side is illustrated as follows:

[0280] Table 1

[0281] In one example, the terminal performed registration in another RAT (such as the fourth RAT) before performing registration in the first RAT (i.e., sending the fourth message).

[0282] In this example, the terminal sending a fourth message to the first core network device through the first access network device corresponding to the first RAT may include: when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the terminal sending a fourth message to the first core network device through the first access network device corresponding to the first RAT.

[0283] In addition to carrying the first instruction information, the fourth message can also carry the NAS identifier for paging corresponding to the fourth RAT. That is, after obtaining the NAS identifier for paging corresponding to the fourth RAT, the terminal can initiate registration with the first core network device through the first access network device corresponding to the first RAT. This first RAT is different from the fourth RAT, the third access network device is different from the first access network device, and the first core network device and the third core network device may be the same or different. The specific processing method for the terminal to establish a fourth NAS connection under the fourth RAT through the third access network device corresponding to the fourth RAT and the third core network device can be the same as the specific processing method for the terminal to establish a first NAS connection under the first RAT through the first access network device corresponding to the first RAT and the first core network device, and will not be elaborated further.

[0284] The first core network device still first determines whether it supports independent multi-access connection management for terminals under different RATs. The determination method is the same as in the aforementioned embodiments and will not be repeated here.

[0285] The processing by the first core network device after determining that it supports independent multi-access connection management for the terminal under different RATs may further include: the first core network device determining a first RAT; the first core network device determining whether to perform registration update or registration under the first RAT; and if it determines that registration is to be performed under the first RAT, the first core network device assigning a NAS identifier for paging corresponding to the first RAT to the terminal. The method by which the first core network device determines the first RAT is the same as in the aforementioned embodiments, and therefore will not be described in detail.

[0286] Optionally, the fourth message may also carry the registration type corresponding to the fourth message. In this case, the first core network device determines whether to perform registration update or registration under the first RAT in the same way as in the previous embodiment, and will not be described again.

[0287] Optionally, the fourth message may not carry the registration type. The first core network device's determination of whether to perform a registration update or registration under the first RAT may include: if the first core network device finds the context corresponding to the first RAT in the context of the terminal, then the first core network device determines to perform a registration update under the first RAT; if the first core network device does not find the context corresponding to the first RAT in the context of the terminal, then the first core network device determines to perform registration under the first RAT.

[0288] The first core network device may obtain the terminal's context in one of the following ways: if the first core network device and the third core network device are the same, the first core network device may directly search for the terminal's context locally; if the first core network device and the third core network device are different, the first core network device may obtain the terminal's context from the third core network device.

[0289] The first core network device can determine the third core network device by: determining the third core network device based on the NAS identifier used for paging corresponding to the fourth RAT. For example, the first core network device first checks locally whether there is a terminal context containing the NAS identifier used for paging corresponding to the fourth RAT of the terminal. If there is, it determines that the third core network device is the same as the first core network device; if not, the first core network device searches among other core network devices for the core network device that stores the NAS identifier used for paging corresponding to the fourth RAT as the third core network device.

[0290] The specific processing method by which the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal is not limited in this embodiment. As long as the NAS identifier for paging corresponding to the first RAT is different from the NAS identifier for paging corresponding to the fourth RAT, it is within the protection scope of this embodiment.

[0291] After the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal, it can send the NAS identifier for paging corresponding to the first RAT to the terminal in the fifth message.

[0292] The processing after the first core network device assigns the NAS identifier for paging corresponding to the first RAT to the terminal may further include: the first core network device adding the NAS identifier for paging corresponding to the first RAT to the terminal's context. Here, adding the NAS identifier for paging corresponding to the first RAT to the terminal's context by the first core network device may include one of the following: if the first core network device is the same as the third core network device and the first core network device locally stores the terminal's context, the NAS identifier for paging corresponding to the first RAT is added to the context corresponding to the first RAT in the terminal's context; if the first core network device is different from the third core network device and the first core network device does not locally store the terminal's context, the first core network device obtains the terminal's context from the third core network device and adds the NAS identifier for paging corresponding to the first RAT to the context corresponding to the first RAT in the terminal's context.

[0293] Furthermore, the processing of the first core network device may also include: the first core network device adding the connection state corresponding to the first RAT to the context of the terminal corresponding to the first RAT.

[0294] In one embodiment, the fourth message is used to perform a registration update on the first RAT, and the fourth message also carries the original NAS identifier for paging corresponding to the first RAT. Correspondingly, the fifth message carries the updated NAS identifier for paging corresponding to the first RAT.

[0295] On the first core network device side, the processing after determining that independent multi-access connection management of the terminal under different RATs is supported may further include: the first core network device determining a first RAT; the first core network device determining whether to perform registration update under the first RAT or to perform registration under the first RAT; if it is determined that to perform registration update under the first RAT, the first core network device assigns the terminal an updated NAS identifier for paging corresponding to the first RAT.

[0296] The method by which the first core network device determines the type of the first RAT is the same as in the previous embodiments and will not be repeated here. The method by which the first core network device determines whether to perform registration updates or registration under the first RAT is the same as in the previous examples and will not be repeated here. The specific processing method by which the first core network device assigns the updated NAS identifier for paging corresponding to the first RAT to the terminal is not limited in this embodiment. As long as the updated NAS identifier for paging corresponding to the first RAT is different from the original NAS identifier for paging corresponding to the first RAT, it is within the protection scope of this embodiment.

[0297] After the first core network device assigns the updated NAS identifier for paging corresponding to the first RAT to the terminal, it can send the updated NAS identifier for paging corresponding to the first RAT to the terminal in a fifth message. This fifth message can be used to indicate that the terminal has successfully updated the first NAS connection under the first RAT between the first access network device and the first core network device and / or successfully updated the registration under the first RAT.

[0298] The processing after the first core network device assigns the updated NAS identifier for paging corresponding to the first RAT to the terminal may further include: the first core network device determining the context corresponding to the first RAT from the context of the terminal based on the type information of the first RAT, deleting the original NAS identifier for paging corresponding to the first RAT stored in the context corresponding to the first RAT, and storing the updated NAS identifier for paging corresponding to the first RAT in the context corresponding to the first RAT.

[0299] Furthermore, the processing of the first core network device may also include: when the connection state corresponding to the first RAT changes or changes, updating and saving the current connection state corresponding to the first RAT to the context of the terminal corresponding to the first RAT.

[0300] In one embodiment, regardless of whether the terminal has not performed registration under other RATs before performing registration under the first RAT (i.e., sending the fourth message), or whether the terminal has performed registration under other RATs before performing registration under the first RAT (i.e., sending the fourth message), or whether the fourth message is used to perform registration update under the first RAT.

[0301] The fourth message also carries type information for one or more third RATs for which the terminal requests independent multi-access connection management. Correspondingly, the fifth message may also carry at least one of the following: different NAS identifiers for paging corresponding to different third RATs among the one or more third RATs; and type information for the one or more third RATs.

[0302] Each of the one or more third RATs is different from the first RAT and also different from the fourth RAT. This means that the terminal can also request the first core network device to assign a corresponding NAS identifier for paging to each of the one or more third RATs via the fourth message. This embodiment does not limit the method by which the first core network device assigns different NAS identifiers for paging to different third RATs.

[0303] The fifth message may carry type information of one or more third RATs, and a NAS identifier for paging corresponding to the type information of each of the one or more third RATs.

[0304] The processing after the first core network device assigns different NAS identifiers for paging corresponding to different third RATs in one or more third RATs to the terminal may further include: the first core network device adding the NAS identifier for paging corresponding to each of the one or more third RATs to the context corresponding to each third RAT in the terminal's context; and / or, the first core network device adding the connection state corresponding to each of the one or more third RATs to the context corresponding to that third RAT in the terminal's context. The relevant descriptions regarding the first core network device updating the terminal's context are similar to those in the aforementioned embodiments and will not be repeated.

[0305] In some possible embodiments, multi-access connection management is performed on the terminal at the connection level.

[0306] The first indication information is used to indicate that the terminal is managed independently under different connections. Different connections correspond to different access network devices, and the RATs corresponding to different access network devices may be the same or different. The connection refers to a logical connection.

[0307] Specifically, the independent multi-access connection management of the terminal under different connections includes at least one of the following: managing the connection status of the terminal under different logical connections; and assigning different NAS identifiers for paging to the terminal corresponding to different logical connections.

[0308] Managing the independent CM states of the terminal under different logical connections can refer to managing the connection states of the multiple logical connections that the terminal can establish, with each logical connection as the granularity. The connection state corresponding to any logical connection can include either an idle state or a connected state.

[0309] Assigning different NAS identifiers for paging to the terminal corresponding to different logical connections can mean assigning different NAS identifiers for paging to the terminal at the connection level, for the multiple logical connections that the terminal can establish.

[0310] Optionally, the step of independently managing multiple access connections for the terminal under different connections includes assigning different NAS identifiers for paging to the terminal corresponding to different logical connections.

[0311] Optionally, the step of independently managing multiple access connections for the terminal under different connections includes managing the connection status of the terminal under different logical connections and assigning different NAS identifiers for paging to the terminal corresponding to different logical connections.

[0312] In one embodiment, after receiving the fourth message from the terminal, the first core network device will also send a fifth message to the terminal through the first access network device.

[0313] The specific transmission process of the fifth message is the same as in the aforementioned embodiments, and the process by which the first core network device determines whether it supports independent multi-access connection management for the terminal under different logical connections is also similar to the aforementioned embodiments. The difference from the aforementioned embodiments is that the second indication information is used to indicate that the first core network device supports independent multi-access connection management for the terminal under different logical connections. Therefore, it will not be elaborated further.

[0314] In one embodiment, the fourth message may be a registration message or a registration request. Specifically, the fourth message is used for the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device; the fifth message carries a NAS identifier for paging corresponding to the first logical connection, which corresponds to the first access network device.

[0315] In one example, the terminal did not perform registration before sending the fourth message.

[0316] The first core network device first determines whether to perform a registration update or registration to establish a first NAS connection under the first logical connection. If it determines that registration is performed under the first RAT to establish a first NAS connection, the first core network device assigns a NAS identifier for paging corresponding to the first logical connection to the terminal. The first core network device can determine the first logical connection based on the NGAP interface corresponding to the fourth message.

[0317] Optionally, the fourth message may also carry a registration type corresponding to the fourth message, which can be initial registration or registration. The first core network device's determination to perform a registration update or registration to establish a first NAS connection on the first logical connection may include: if the registration type carried in the fourth message is initial registration or registration, the first core network device determines to perform registration to establish a first NAS connection under the first logical connection; if the registration type carried in the fourth message is registration update (e.g., any one of mobility registration update or periodic registration), the first core network device determines to perform a registration update on the first logical connection.

[0318] Optionally, the fourth message may not carry a registration type. The first core network device's determination of whether to perform a registration update or to establish a first NAS connection on the first logical connection may include: if the first core network device finds the context of the terminal locally, and the terminal's context includes the context corresponding to the first logical connection, the first core network device determines to perform a registration update on the first logical connection; if the first core network device does not find the context of the terminal locally, and / or the terminal's context does not include the context corresponding to the first logical connection, the first core network device determines to perform registration to establish a first NAS connection on the first logical connection.

[0319] The specific processing method by which the first core network device assigns the NAS identifier for paging corresponding to the first logical connection to the terminal is not limited in this embodiment.

[0320] After the first core network device assigns the NAS identifier for paging corresponding to the first logical connection to the terminal, it can send the NAS identifier for paging corresponding to the first logical connection to the terminal in the fifth message.

[0321] The processing after the first core network device assigns the NAS identifier for paging corresponding to the first logical connection to the terminal may further include: the first core network device adding the NAS identifier for paging corresponding to the first logical connection to the context of the terminal.

[0322] Specifically, the first core network device can store or maintain the terminal's context. In this embodiment, the terminal's context may include the context corresponding to each connection under each RAT. This context corresponding to each connection can also be referred to as the context of each connection level within the UE access and mobility context. The first core network device adds the NAS identifier for paging corresponding to the first logical connection to the terminal's context. This can be achieved by the first core network device adding the connection identifier (ID) of the first logical connection and the NAS identifier for paging corresponding to the first logical connection to the context of the terminal's context corresponding to the first logical connection.

[0323] Furthermore, the processing of the first core network device may also include: the first core network device adding the connection state corresponding to the first logical connection to the context of the terminal corresponding to the first connection. The connection state corresponding to the first connection refers to the connection state of the terminal corresponding to the first NAS connection, which may include one of the following: idle state, connected state.

[0324] Referring to Table 2, taking the first core network device as the AMF as an example, the UE context on the AMF side is illustrated as follows:

[0325] Table 2

[0326] In one example, the terminal performed registration and established other NAS connections before sending the fourth message.

[0327] In this example, the terminal sending a fourth message to the first core network device through the first access network device may include: when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the terminal sending a fourth message to the first core network device through the first access network device.

[0328] In addition to carrying the first instruction information, the fourth message may also carry the NAS identifier for paging corresponding to the fourth logical connection (which corresponds to the third access network device). The third access network device is different from the first access network device, and the first core network device may be the same as or different from the third core network device.

[0329] The first core network device determines whether it supports independent multi-access connection management for terminals under different logical connections. The determination method is the same as in the aforementioned embodiments and will not be repeated here.

[0330] The processing of the first core network device after determining that it supports independent multi-access connection management for the terminal under different logical connections may further include: the first core network device determining whether to perform registration update or registration under the first logical connection; if it is determined that registration is performed under the first RAT, the first core network device assigns a NAS identifier for paging corresponding to the first logical connection to the terminal.

[0331] In this example, the first core network device determines the processing method of performing registration update or registration in the first logical connection, identifies the third core network device, and obtains the context of the terminal saved by the third core network device, which are the same as in the previous embodiments and will not be described again.

[0332] The specific processing method by which the first core network device assigns the NAS identifier for paging corresponding to the first logical connection to the terminal is not limited in this embodiment. As long as the NAS identifier for paging corresponding to the first logical connection is different from the NAS identifier for paging corresponding to the fourth logical connection, it is within the protection scope of this embodiment.

[0333] After the first core network device assigns a NAS identifier for paging corresponding to the first logical connection to the terminal, it can send the NAS identifier for paging corresponding to the first logical connection to the terminal in the fifth message.

[0334] The processing after the first core network device assigns a NAS identifier for paging corresponding to the first logical connection to the terminal may further include: the first core network device adding the NAS identifier for paging corresponding to the first logical connection to the terminal's context. Here, adding the NAS identifier for paging corresponding to the first logical connection to the terminal's context by the first core network device may include one of the following: if the first core network device is the same as the third core network device and the first core network device locally stores the terminal's context, the NAS identifier for paging corresponding to the first logical connection is added to the context corresponding to the first logical connection in the terminal's context; if the first core network device is different from the third core network device and the first core network device does not locally store the terminal's context, the first core network device obtains the terminal's context from the third core network device and adds the NAS identifier for paging corresponding to the first logical connection to the context corresponding to the first logical connection in the terminal's context.

[0335] The processing of the first core network device may also include: the first core network device adding the connection state corresponding to the first logical connection to the context of the terminal.

[0336] In one embodiment, the fourth message is used to perform a registration update on the first logical connection, and the fourth message also carries the original NAS identifier for paging corresponding to the first logical connection; the fifth message carries the updated NAS identifier for paging corresponding to the first logical connection under the first RAT.

[0337] The processing of the first core network device may further include: if it is determined that a registration update is performed on the first logical connection, the first core network device assigns the terminal an updated NAS identifier for paging corresponding to the first logical connection.

[0338] The first core network device may determine the first logical connection in the following ways: if the fourth message carries an identifier of the first logical connection, the first logical connection is determined based on the identifier; if the fourth message does not carry an identifier of the first logical connection, the first logical connection is determined based on the NGAP interface corresponding to the fourth message. The method by which the first core network device determines whether to perform a registration update or perform registration on the first logical connection is the same as in the previous example and will not be described again.

[0339] The specific processing method by which the first core network device assigns the updated NAS identifier for paging corresponding to the first logical connection to the terminal is not limited in this embodiment. As long as the updated NAS identifier for paging corresponding to the first logical connection is different from the original NAS identifier for paging corresponding to the first logical connection, it is within the protection scope of this embodiment.

[0340] After the first core network device assigns the updated NAS identifier for paging corresponding to the first logical connection to the terminal, it can send the updated NAS identifier for paging corresponding to the first logical connection to the terminal in a fifth message. This fifth message can be used to indicate that the terminal has successfully updated the first logical connection between the first access network device and the first core network device and / or that the registration update of the first logical connection has been successful.

[0341] The processing after the first core network device allocates the updated NAS identifier for paging corresponding to the first logical connection to the terminal may further include: the first core network device determining the context corresponding to the first logical connection from the terminal's context based on the connection identifier of the first logical connection, deleting the original NAS identifier for paging corresponding to the first logical connection stored in the context corresponding to the first logical connection, and storing the updated NAS identifier for paging corresponding to the first logical connection in the context corresponding to the first logical connection. Further, the processing of the first core network device may also include: if the connection state corresponding to the first logical connection changes or transforms, updating and saving the current connection state corresponding to the first logical connection to the context corresponding to the first logical connection in the terminal's context.

[0342] In one embodiment, regardless of whether the terminal has established other NAS connections before sending the fourth message, or whether the fourth message is used to perform a registration update on the first logical connection.

[0343] The fourth message also carries the identifiers of one or more third logical connections for which the terminal requests independent multi-access connection management, wherein different third logical connections correspond to different fourth access network devices, and the RATs corresponding to different fourth access network devices may be the same or different. Correspondingly, the fifth message may also carry at least one of the following: different NAS identifiers for paging corresponding to different third logical connections among the one or more third logical connections; connection identifiers of the one or more third logical connections.

[0344] Each of the one or more third logical connections is different from the first logical connection and also different from the fourth logical connection. This means that the terminal can request the first core network device to assign a corresponding NAS identifier for paging to each of the one or more third logical connections via the fourth message. This embodiment does not limit the method by which the first core network device assigns different NAS identifiers for paging to different third logical connections.

[0345] The fifth message may carry the connection identifier of the one or more third logical connections, and the NAS identifier for paging corresponding to the connection identifier of each of the one or more third logical connections.

[0346] The processing of the first core network device may further include: the first core network device adding the NAS identifier for paging corresponding to each of the one or more third logical connections to the context corresponding to each third logical connection in the context of the terminal; and the first core network device adding the connection state corresponding to each third logical connection to the context corresponding to each third logical connection in the context of the terminal.

[0347] Referring to Figure 13, taking the first core network device as MM and the terminal as UE as an example, the following example illustrates how to allocate a NAS identifier for paging for the first connection of the UE:

[0348] Step 1301: The UE sends a NAS message (i.e., the fourth message) to the MM through the first access network device corresponding to the first RAT (e.g., 6G RAN (Radio Access Network under 6G) shown in Figure 13). This NAS message can be a registration request.

[0349] The registration request may be used to instruct the network (e.g., MM) to at least one of the following: the UE requests to establish a connection, the UE requests to assign a NAS identifier for paging to a first RAT, or the UE requests to assign a NAS identifier for paging to the current logical connection (the first logical connection, which corresponds to the first access network device).

[0350] Specifically, the registration request may carry at least one of the following information: first indication information, type information of one or more third RATs for which the UE requests separate connection management, and connection ID of one or more third logical connections for which the UE requests separate connection management.

[0351] The first indication information can be used to instruct the mobility management network element to perform independent connection management (or multiple access connection management) on different logical connections of the UE, or to instruct the mobility management network element to perform independent connection management (or multiple access connection management) on different RATs of the UE.

[0352] The first indication information may be UE capability information, such as multi-access capability, independent connection management capability based on RAT, etc. If the network supports and authorizes the UE's multi-access, the mobility management network element can perform separate connection management for the connections corresponding to different RATs of the UE, or separate connection management for different logical connections of the UE.

[0353] Alternatively, the first indication information may be new indication information, used to instruct the network to perform separate connection management for connections corresponding to different RATs of the UE, or to perform separate connection management for different logical connections of the UE.

[0354] The connection identifier for the third logical connection: This is a logical connection used to indicate that the UE requests separate connection management. The connection identifier can be the identifier of the logical connection assigned to the UE by the network after successful UE registration. Alternatively, the connection identifier for the third logical connection can be replaced with the AMF UE NGAP ID and / or RAN UE NGAP ID corresponding to the third logical connection.

[0355] It should be noted that the above is only an exemplary description of the content or information that the registration request may carry. In actual processing, the registration request may also carry other content specified by the relevant protocol. For example, the registration request may also carry the UE's identification information, which may include at least one of the following: SUPI (Subscription Permanent Identifier), SUCI (Subscription Concealed Identifier), or GUTI (if the network has previously assigned one to this UE).

[0356] In step 1302, the MM sends a registration acceptance message (i.e., the fifth message) to the UE through the first access network device. The registration acceptance message may carry GUTI-1, which may be the NAS identifier for paging corresponding to the first RAT or the NAS identifier for paging corresponding to the first logical connection.

[0357] Specifically, the Mobility Management Element (MM) determines whether it supports RAT-based connection management (or separate management of each logical connection) for the UE based on at least one of the UE's subscription information (which can be obtained from the UDM), local configuration, and network capabilities. If supported, the MM assigns a paging identifier (GUTI-1) to the first RAT (or first logical connection), maintains the connection management state separately for the first RAT (or first logical connection) of the UE, and updates the context portion corresponding to the first RAT (or first logical connection) in the UE context.

[0358] In this example, the registration acceptance message may carry at least one of the following in addition to GUTI-1: second indication information (indicating that the network supports RAT-based connection management for the UE (or individual management for each logical connection)), type information of one or more third RATs, connection identifiers of one or more third logical connections, NAS identifiers for paging corresponding to each of the one or more third RATs, and NAS identifiers for paging corresponding to each of the one or more third logical connections. The NAS identifiers for paging differ between different third RATs and between different third logical connections.

[0359] It should be noted that the above is only an exemplary description of the content or information that the registration acceptance message may carry. In actual processing, the registration acceptance message may also carry other content stipulated by the relevant agreement, which is not limited or exhaustive here.

[0360] Referring to Figure 14, taking the first core network device as MM and the terminal as UE as an example, the following example illustrates how to allocate a NAS identifier for paging in the second connection of the UE:

[0361] Step 1401: The UE sends a NAS message (i.e., the fourth message) to the MM through the first access network device corresponding to the first RAT (e.g., 5G RAN in Figure 14). The NAS message can be a registration request, which can be an initial registration or a registration update request.

[0362] In this example, the UE may have already completed registration and established a NAS connection. For example, the UE may have completed registration and established a fourth NAS connection in the fourth RAT. Then, the UE performs step 1401 to register to the second network. At this time, the registration request can carry the NAS identifier for paging that was previously assigned to it by the MM and instruct the network to assign a new NAS identifier for paging to its second connection.

[0363] For example, the UE may have completed registration and established the first NAS connection in the first RAT. Then, the UE performs step 901 to register to the second network. At this time, the registration request can carry the original NAS identifier assigned to it by the MM for paging in the previous instance, and indicate that the network is the updated NAS identifier for paging.

[0364] Specifically, the registration request may include at least one of the following parameters: the NAS identifier assigned to it by the MM for paging in the last time, the first indication information, the connection identifier of one or more third logical connections for which the UE requests separate connection management, the type information of one or more third RATs for which the UE requests separate connection management, and the registration type.

[0365] The NAS identifier assigned to it by the MM for paging in the last time can be represented as GUTI-1. GUTI-1 can be the NAS identifier for paging corresponding to the fourth RAT, or the NAS identifier for paging corresponding to the fourth connection; or, GUTI-1 can be the original NAS identifier for paging corresponding to the first RAT, or the original NAS identifier for paging corresponding to the first NAS connection.

[0366] Registration types can include one of the following: initial registration, mobility registration update, periodic registration, emergency registration, etc.

[0367] In step 1402, the MM sends a registration acceptance message (i.e., the fifth message) to the UE through the first access network device. The registration acceptance message may carry GUTI-2 or GUTI-1*. GUTI-2 may be the NAS identifier for paging corresponding to the first RAT or the NAS identifier for paging corresponding to the first RAT logical connection. GUTI-1* may be the updated NAS identifier for paging corresponding to the first RAT or the updated NAS identifier for paging corresponding to the first logical connection.

[0368] Specifically, after receiving the registration request message, the MM assigns a new paging identification information GUTI-2 to the UE. This can be divided into the following two cases:

[0369] The UE performs a registration update for the existing first RAT type (or first logical connection), the MM assigns a new GUTI-1* to the first RAT (or first logical connection), and updates the context corresponding to the first RAT (or first logical connection) in the corresponding UE context.

[0370] The UE performs a registration request for the new first RAT type (or the new first logical connection), the MM assigns a GUTI-2 to the first RAT (or the first logical connection), and adds the context corresponding to the first RAT (or the first logical connection) to the UE context.

[0371] In addition to carrying GUTI-2 or GUTI-1*, the registration acceptance message may also carry at least one of the following: second indication information, type information of one or more third RATs, connection identifier of one or more third logical connections, NAS identifier for paging corresponding to each of the one or more third RATs, and NAS identifier for paging corresponding to each of the one or more third logical connections. Wherein, if the mobility management element MM corresponding to GUTI-1 is a different network element from the mobility management element MM* that received the NAS message in step 1401, then MM* needs to obtain the UE context from the MM.

[0372] The above embodiments illustrate the capability negotiation between the terminal and the network, enabling the network to flexibly enable RAT-based connection management and individual connection management for the UE based on UE capabilities and network capabilities, ensuring backward compatibility of the network. The network (such as the first core network device) can allocate multiple paging identifiers to the UE according to connection and / or RAT granularity, allowing the network side to paging the UE individually on different RATs or connections. Furthermore, using different GUTIs to refer to different RATs, carrying only the corresponding GUTI in the paging message helps the UE determine that the network requires it to establish a connection on a specific RAT. Compared to carrying the RAT type or connection identifier in the paging message, this reduces the number of bits occupied by the paging message, improves the utilization of air interface resources, reduces the risk of information leakage due to paging message eavesdropping, and ensures the security of the paging message. Simultaneously, managing the UE connection status separately according to RAT or NAS connection also helps to decouple the UE connection management on different RATs, providing technical support for the network to send data to the UE according to the RAT.

[0373] In some possible implementations, before the terminal receives the first message from the first RAT, the method further includes: when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the terminal sends a sixth message to the first core network device through the first access network device corresponding to the first RAT, wherein the sixth message carries third indication information, the third indication information being used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

[0374] Before the first access network device receives the first message from the first core network device, the method further includes: the first access network device sending a sixth message from the terminal to the first core network device, wherein the sixth message carries third indication information, the third indication information being used to indicate that the same NAS identifier for paging corresponding to different RATs is assigned to the terminal.

[0375] Before the first core network device sends the first message in the first RAT, the method further includes: when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the first core network device receives a sixth message from the terminal through the first access network device corresponding to the first RAT, wherein the sixth message carries third indication information, the third indication information being used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

[0376] In this embodiment, the fourth RAT is different from the first RAT. The third access network device and the third core network device can belong to the third network, and the first access network device and the first core network device can belong to the first network. The first network and the third network are different. When the first network and the third network share the same core network, the third core network device and the first core network device can be the same or different; when the first network and the third network use different core networks, the third core network device and the first core network device are different.

[0377] The specific processing method for the terminal to establish the fourth NAS connection under the fourth RAT is not limited in this embodiment.

[0378] The sixth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device. Specifically, the sixth message can be a registration message, which may or may not carry a registration type. If the sixth message carries a registration type, the registration type can be initial registration.

[0379] After receiving the sixth message, the first core network device can determine whether it supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs based on at least one of the following: UE subscription information, local configuration, and network capabilities. This embodiment does not limit the specific determination method of the first core network device.

[0380] After the first core network device receives the sixth message from the terminal through the first access network device corresponding to the first RAT, and the first core network device determines that it supports allocating the same NAS identifier for paging corresponding to different RATs for the terminal, it can perform the following process: the first core network device sends a seventh message to the terminal through the first access network device, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports allocating the same NAS identifier for paging corresponding to different RATs for the terminal.

[0381] After the first access network device sends the sixth message from the terminal to the first core network device, the method further includes: the first access network device sending a seventh message from the first core network device to the terminal, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports allocating the same NAS identifier for paging corresponding to different RATs for the terminal.

[0382] After the terminal sends a sixth message to the first core network device through the first access network device corresponding to the first RAT, the method further includes: the terminal receiving a seventh message from the first core network device through the first access network device, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports allocating the same NAS identifier for paging corresponding to different RATs for the terminal.

[0383] The sixth message may also carry at least one of the following: the NAS identifier for paging corresponding to the fourth RAT, and the type information of the fourth RAT.

[0384] In one scenario, the sixth message may carry the type information of the fourth RAT but not the NAS identifier for paging corresponding to the fourth RAT. If the first core network device determines that it supports assigning the same NAS identifier for paging to different RATs for the terminal, it can also determine the context corresponding to the fourth RAT from the terminal's context based on the fourth RAT's type information, extract the NAS identifier for paging corresponding to the fourth RAT from the context corresponding to the fourth RAT, and then use the NAS identifier for paging corresponding to the fourth RAT as the NAS identifier for paging corresponding to the first RAT, adding the NAS identifier for paging corresponding to the first RAT to the context corresponding to the first RAT in the terminal's context.

[0385] In one scenario, the sixth message may carry the type information of the fourth RAT and the NAS identifier for paging corresponding to the fourth RAT. If the first core network device determines that it supports assigning the same NAS identifier for paging to different RATs for the terminal, it may also use the NAS identifier for paging corresponding to the fourth RAT as the NAS identifier for paging corresponding to the first RAT, and add the NAS identifier for paging corresponding to the first RAT to the context corresponding to the first RAT in the terminal's context.

[0386] Optionally, the seventh message may only carry the fourth indication information. In this case, after receiving the fourth indication information in the seventh message, the terminal can determine that the first core network device has assigned the same NAS identifier for paging to the terminal corresponding to different RATs. Then, the terminal can directly use the NAS identifier for paging corresponding to the fourth RAT as the NAS identifier for paging corresponding to the first RAT.

[0387] Optionally, the seventh message may carry fourth indication information and a paging NAS identifier corresponding to the first RAT, wherein the paging NAS identifier corresponding to the first RAT is the same as the paging NAS identifier corresponding to the fourth RAT. In this case, after receiving the seventh message, the terminal can determine from the fourth indication information that the first core network device has allocated the same paging NAS identifier to the terminal for different RATs, and from the paging NAS identifier corresponding to the first RAT, it can determine that the first core network device has allocated the same paging NAS identifier to both the fourth RAT and the first RAT.

[0388] In one example, in addition to carrying the fourth indication information, the seventh message may also carry at least one of the following: type information of one or more fifth RATs; the same NAS identifier used for paging under the one or more fifth RATs. Wherein, the same NAS identifier used for paging under the one or more fifth RATs is the same as the NAS identifier used for paging corresponding to the fourth RAT.

[0389] In one scenario, one or more fifth RATs can be indicated by the terminal, meaning that the type information of one or more fifth RATs can be carried in the sixth message.

[0390] In one scenario, one or more fifth RATs can be determined by the first core network device. For example, if the first core network device determines that it supports assigning the same NAS identifier for paging to different RATs for the terminal, it can also determine one or more fifth RATs that are different from the first RAT and different from the fourth RAT. The NAS identifier for paging corresponding to each of the one or more fifth RATs is set to be the same as the NAS identifier for paging corresponding to the fourth RAT, and added to the context corresponding to each fifth RAT in the terminal's context. These one or more fifth RATs can be one or more RATs assigned to the terminal by the first core network device that use the same NAS identifier for paging as the fourth RAT. This embodiment does not limit the specific method by which the first core network device determines the fifth RAT.

[0391] Optionally, the seventh message may carry fourth indication information and type information of one or more fifth RATs, wherein the one or more fifth RATs do not include the first RAT and do not include the fourth RAT. In this case, after receiving the seventh message, the terminal can determine through the fourth indication information that the first core network device has assigned the same NAS identifier for paging to the terminal corresponding to different RATs. Then, the terminal can directly use the NAS identifier for paging corresponding to the fourth RAT as the NAS identifier for paging corresponding to the first RAT. Furthermore, the terminal can determine through the type information of one or more fifth RATs that the first core network device has also assigned the NAS identifier for paging corresponding to the fourth RAT to each fifth RAT.

[0392] Optionally, the seventh message may carry fourth instruction information, type information of one or more fifth RATs, and a NAS identifier for paging, wherein the one or more fifth RATs do not include the fourth RAT, and the one or more fifth RATs may include or exclude the first RAT.

[0393] If one or more fifth RATs do not contain a first RAT, after receiving the seventh message, the terminal can determine through the fourth indication information that the first core network device has assigned the terminal the same NAS identifier for paging corresponding to different RATs. Then, the terminal can directly use the NAS identifier for paging carried in the seventh message as the NAS identifier for paging corresponding to the first RAT. Furthermore, the terminal can determine through the type information of one or more fifth RATs that the first core network device has also assigned the NAS identifier for paging to each fifth RAT.

[0394] If one or more fifth RATs contain the first RAT, then after the terminal receives the seventh message, it can determine through the fourth indication information that the first core network device has assigned the same NAS identifier for paging to the terminal corresponding to different RATs. The terminal can determine through the type information of one or more fifth RATs that the first core network device has simultaneously assigned the NAS identifier for paging corresponding to the fourth RAT to each fifth RAT.

[0395] This embodiment provides an exemplary illustration of a scenario where a terminal is assigned the same NAS identifier for paging under different RATs. For example, in a scenario where 5GS interworking with EPS (Evolved Packet System), the MME and AMF assign different NAS identifiers for paging to the UE. When the terminal switches from 5GS to EPS, it needs to map the 5G GUTI to the 4G GUTI, or when it switches from EPS to 5GS, it needs to map the 4G GUTI to the 5G GUTI. Since the terminal only uses one NAS connection (connected to the MME or AMF) at any given time, this obviously introduces an additional workload for both the terminal and the network to maintain two UEs. To simplify this process, the terminal can instruct the mobility management element to assign the same paging identifier to the terminal on different RATs in the registration request or attach request message.

[0396] Referring to Figure 15, taking the first core network device as the Mobility Management Element (MM) and the terminal as the UE as an example, the following is an exemplary illustration of assigning the same NAS identifier for paging to different RATs of the UE:

[0397] Step 1501: The UE sends a NAS message (i.e., the sixth message) to the MM through the first access network device (e.g., RAN in Figure 15) corresponding to the first RAT. The NAS message can be a registration request, which can be an initial registration.

[0398] In this example, the UE may have already completed registration and established a NAS connection. For instance, the UE may have completed registration and established a fourth NAS connection on the fourth RAT. Then, when the UE executes step 1501 to register with the second network and establish a second NAS connection, it sends the registration request message to the network. The registration request message contains the following parameters: UE identification information such as GUTI-1, which is the NAS identifier assigned to the UE for paging on the previous RAT (fourth RAT); third indication information; and type information for one or more fifth RATs, i.e., the MM uses the NAS identifier for paging provided by the UE on each fifth RAT corresponding to the previous RAT.

[0399] In step 1502, the MM sends a registration acceptance message (i.e., the seventh message) to the UE through the first access network device. This registration acceptance message may carry GUTI-1 and fourth indication information.

[0400] Specifically, after receiving the registration request message, if the MM supports assigning the same GUTI to multiple RATs, it can update the UE context so that multiple RATs correspond to the same UE identifier (GUTI-1) for paging, and carry at least one of the following information in the registration receive message:

[0401] The fourth instruction information is used to instruct the UE network side to use the same paging identifier (GUTI-1) on multiple RATs;

[0402] The type information of one or more fifth RATs uses the same GUTI-1 RAT type. The one or more fifth RATs can be indicated by the UE in step 1501 (i.e., the type information of one or more fifth RATs can be carried in the sixth message), or can be determined by the MM based on local configuration, network capabilities, operator configuration and / or UE subscription information. The specific determination method is not limited in this embodiment.

[0403] GUTI-1 is an identifier used to page a UE on multiple RATs.

[0404] Generally, a new GUTI needs to be configured for the UE after each pager. Maintaining multiple GUTIs for multiple RATs simultaneously leads to significant signaling and storage overhead. Especially in 5GS interworking with EPS scenarios, by adopting the above embodiments, the network side can use the same GUTI to page the UE on some RATs, which simplifies GUTI management for both the network and the UE.

[0405] By adopting the above scheme, the terminal can receive the first message under the first RAT to trigger the execution of operations related to the second RAT. In this way, the terminal can receive messages under one RAT to perform related operations on another RAT. Thus, when the terminal has the ability to access the network under multiple RATs, it can achieve collaborative operation under multiple RATs, ensuring the continuity of terminal services and the efficiency of data or message transmission.

[0406] Figure 16 is a schematic diagram of the composition structure of a terminal according to an embodiment of this application, including:

[0407] The first communication unit 1601 is used to receive a first message in the first RAT, wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0408] The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a NAS connection in the second RAT.

[0409] The first message carries at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, or the RAT corresponding to the downlink message to be transmitted; a first timer, wherein the duration of the first timer is one of the following: the maximum duration for the terminal to initiate or complete the establishment of a NAS connection in the second RAT, or the maximum duration for the terminal to initiate or complete the establishment of user plane resources in the second RAT.

[0410] The first communication unit is used to send a second message to the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

[0411] The second message is also used to establish the user plane resource corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session.

[0412] The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

[0413] The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

[0414] The first message carries at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the second session that needs to be rebuilt; the identifier of the second session; a second timer, wherein the duration of the second timer is the maximum duration for the terminal to initiate or complete the reconstruction of the second session corresponding to the second RAT on the first RAT; and an instruction to rebuild the second session corresponding to the second RAT on the first RAT.

[0415] The first communication unit is configured to perform one of the following: send a service request to a first access network device corresponding to the first RAT, wherein the service request carries a third message, the third message being used to request the reconstruction of the second session corresponding to the second RAT in the first RAT; or send a session modification request to a first core network device through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

[0416] The third message carries at least one of the following: an identifier of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT; or a NAS identifier for paging corresponding to the first RAT.

[0417] The second RAT is the same as the first RAT.

[0418] The second RAT is different from the first RAT.

[0419] The first communication unit is configured to receive a first paging message from a first access network device corresponding to the first RAT, wherein the first paging message carries the first message and the first message carries a NAS identifier for paging corresponding to the first RAT.

[0420] The first communication unit is configured to receive a NAS notification message from a first core network device via a first access network device corresponding to a first RAT, wherein the NAS notification message carries the first message.

[0421] The first communication unit is configured to send a fourth message to the first core network device through the first access network device corresponding to the first RAT, wherein the fourth message carries first indication information, which is used to indicate that the terminal is managed independently under different RATs.

[0422] The independent multi-access connection management of the terminal under different RATs includes at least one of the following: managing the connection status of the terminal under different RATs; assigning different NAS identifiers for paging to the terminal corresponding to different RATs.

[0423] The first communication unit is configured to receive a fifth message from the first core network device via the first access network device, wherein the fifth message carries second indication information, the second indication information being used to instruct the first core network device to support independent multi-access connection management for the terminal under different RATs.

[0424] The fourth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

[0425] The fifth message carries the NAS identifier for paging corresponding to the first RAT.

[0426] The fourth message is used to perform a registration update in the first RAT, and the fourth message also carries the original NAS identifier corresponding to the first RAT for paging.

[0427] The fifth message carries the updated NAS identifier for paging corresponding to the first RAT.

[0428] The fourth message also carries type information of one or more third RATs for the terminal to request independent multi-access connection management.

[0429] The fifth message also carries at least one of the following: different NAS identifiers for paging corresponding to different third RATs in the one or more third RATs; type information of the one or more third RATs.

[0430] The first communication unit is configured to send a sixth message to the first core network device through the first access network device corresponding to the first RAT when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT. The sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

[0431] The sixth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

[0432] The sixth message also carries at least one of the following: the NAS identifier for paging corresponding to the fourth RAT; and the type information of the fourth RAT.

[0433] The first communication unit is configured to receive a seventh message from the first core network device via the first access network device, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs.

[0434] The seventh message also carries at least one of the following: type information for one or more fifth RATs; the same NAS identifier used for paging under one or more fifth RATs.

[0435] Figure 17 is a schematic diagram of the composition structure of a first core network device according to an embodiment of this application, including:

[0436] The second communication unit 1701 is used to send a first message in the first wireless access technology (RAT), wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

[0437] The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a non-access stratum NAS connection in the second RAT.

[0438] The first message carries at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, or the RAT corresponding to the downlink message to be transmitted; a first timer, wherein the duration of the first timer is one of the following: the maximum duration for the terminal to initiate or complete the establishment of a NAS connection in the second RAT, or the maximum duration for the terminal to initiate or complete the establishment of user plane resources in the second RAT.

[0439] The second communication unit is used to receive a second message sent by the terminal through the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

[0440] The second message is also used to establish the user plane resource corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session.

[0441] The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

[0442] The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

[0443] The first message carries at least one of the following: type information of the second RAT, wherein the second RAT is the RAT corresponding to the second session that needs to be rebuilt; the identifier of the second session; a second timer, wherein the duration of the second timer is the maximum duration for the terminal to initiate or complete the reconstruction of the second session corresponding to the second RAT on the first RAT; and an instruction to rebuild the second session corresponding to the second RAT on the first RAT.

[0444] The second communication unit is configured to perform one of the following: receive a service request through a first access network device corresponding to the first RAT, wherein the service request carries a third message, the third message being used to request the reconstruction of the second session corresponding to the second RAT in the first RAT; or receive a session modification request from the terminal through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

[0445] The third message carries at least one of the following: an identifier of one or more sessions corresponding to the second RAT that the terminal allows to be rebuilt on the first RAT; or a NAS identifier for paging corresponding to the first RAT.

[0446] The second RAT is the same as the first RAT.

[0447] The second RAT is different from the first RAT.

[0448] The second communication unit is configured to send a second paging message to the first access network device corresponding to the first RAT, wherein the second paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

[0449] The second paging message also carries a registration area list, wherein the registration area list is used by the first access network device to determine the cell from which the terminal is being paged.

[0450] The second communication unit is used to send a NAS notification message to the terminal through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message.

[0451] The second communication unit is configured to receive a fourth message from the terminal through the first access network device corresponding to the first RAT, wherein the fourth message carries first indication information, which is used to indicate independent multi-access connection management for the terminal under different RATs.

[0452] The independent multi-access connection management of the terminal under different RATs includes at least one of the following: managing the connection status of the terminal under different RATs; assigning different NAS identifiers for paging to the terminal corresponding to different RATs.

[0453] The second communication unit is used to send a fifth message to the terminal through the first access network device, wherein the fifth message carries second indication information, the second indication information being used to instruct the first core network device to support independent multi-access connection management of the terminal under different RATs.

[0454] The fourth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

[0455] The fifth message carries the NAS identifier for paging corresponding to the first RAT.

[0456] The fourth message is used to perform a registration update in the first RAT, and the fourth message also carries the original NAS identifier corresponding to the first RAT for paging.

[0457] The fifth message carries the updated NAS identifier for paging corresponding to the first RAT.

[0458] The fourth message also carries type information of one or more third RATs for the terminal to request independent multi-access connection management.

[0459] The fifth message also carries at least one of the following: different NAS identifiers for paging corresponding to different third RATs in the one or more third RATs; type information of the one or more third RATs.

[0460] The second communication unit is configured to receive a sixth message from the terminal via the first access network device corresponding to the first RAT when the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device corresponding to the fourth RAT. The sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

[0461] The sixth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

[0462] The sixth message also carries at least one of the following: the NAS identifier for paging corresponding to the fourth RAT; and the type information of the fourth RAT.

[0463] The second communication unit is configured to send a seventh message to the terminal via the first access network device, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs.

[0464] The seventh message also carries at least one of the following: type information for one or more fifth RATs; the same NAS identifier used for paging under one or more fifth RATs.

[0465] Figure 18 is a schematic diagram of the composition structure of a first access network device according to an embodiment of this application, including:

[0466] The third communication unit 1801 is configured to receive a first message from a first core network device, wherein the first access network device corresponds to a first radio access technology (RAT), and the first message is configured to trigger the terminal to perform an operation related to a second RAT; and to send the first message to the terminal.

[0467] The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a non-access stratum NAS connection in the second RAT.

[0468] The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

[0469] The third communication unit is configured to receive a service request from the terminal, wherein the service request carries a third message, the third message being configured to request that the second session corresponding to the second RAT be re-established in the first RAT; and to send the service request to the first core network device.

[0470] The third communication unit is configured to receive a session modification request from the terminal, wherein the session modification request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; and to send the session modification request to the first core network device.

[0471] The second RAT is the same as the first RAT.

[0472] The second RAT is different from the first RAT.

[0473] The third communication unit is configured to receive a second paging message from the first core network device, wherein the second paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

[0474] The second paging message also carries a registration area list, wherein the registration area list is used by the first access network device to determine the cell from which the terminal is being paged.

[0475] The third communication unit is used to send a first paging message to the terminal, wherein the first paging message carries the first message.

[0476] The third communication unit is configured to receive a NAS notification message from the first core network device, wherein the NAS notification message carries the first message; and to send the first message to the terminal, including: the first access network device sending the NAS notification message to the terminal.

[0477] The third communication unit is used to send a fourth message from the terminal to the first core network device, wherein the fourth message carries first indication information, which is used to indicate that the terminal should be managed independently under different RATs.

[0478] The third communication unit is used to send a fifth message from the first core network device to the terminal, wherein the fifth message carries second indication information, which is used to indicate that the first core network device supports independent multi-access connection management for the terminal under different RATs.

[0479] The third communication unit is used to send a sixth message from the terminal to the first core network device, wherein the sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

[0480] The third communication unit is used to send a seventh message from the first core network device to the terminal, wherein the seventh message carries fourth indication information, the fourth indication information being used to indicate that the first core network device supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs.

[0481] The device in this application embodiment can realize the corresponding functions of the various devices in the foregoing key generation method embodiments. The processes, functions, implementation methods, and beneficial effects of each module (sub-module, unit, or component, etc.) in this device can be found in the corresponding descriptions in the above method embodiments, and will not be repeated here. It should be noted that the functions described for each module (sub-module, unit, or component, etc.) in the device of this application embodiment can be implemented by different modules (sub-modules, units, or components, etc.) or by the same module (sub-module, unit, or component, etc.).

[0482] Figure 19 is a schematic structural diagram of a communication device 1900 according to an embodiment of this application. The communication device 1900 includes a processor 1910, which can call and run computer programs from a memory to enable the communication device 1900 to implement the methods in the embodiments of this application. In one possible implementation, the communication device 1900 may further include a memory 1920. The processor 1910 can call and run computer programs from the memory 1920 to enable the communication device 1900 to implement the methods in the embodiments of this application. The memory 1920 may be a separate device independent of the processor 1910, or it may be integrated into the processor 1910. In one possible implementation, the communication device 1900 may further include a transceiver 1930, which the processor 1910 can control to communicate with other devices. Specifically, it can send information or data to other devices or receive information or data sent by other devices. The transceiver 1930 may include a transmitter and a receiver. The transceiver 1930 may further include antennas, and the number of antennas may be one or more.

[0483] In one possible implementation, the communication device 1900 may be a terminal, a first core network device, or a first access network device in the embodiments of this application, and the communication device 1900 may implement the corresponding processes implemented by the terminal, the first core network device, or the first access network device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0484] Figure 20 is a schematic structural diagram of a chip 2000 according to an embodiment of this application. The chip 2000 includes a processor 2010, which can call and run computer programs from memory to implement the methods in the embodiments of this application. In one possible implementation, the chip 2000 may further include a memory 2020. The processor 2010 can call and run computer programs from the memory 2020 to implement the methods executed by a terminal, a first core network device, or a first access network device in the embodiments of this application. The memory 2020 may be a separate device independent of the processor 2010, or it may be integrated into the processor 2010. In one possible implementation, the chip 2000 may further include an input interface 2030. The processor 2010 can control the input interface 2030 to communicate with other devices or chips; specifically, it can acquire information or data sent by other devices or chips. In one possible implementation, the chip 2000 may further include an output interface 2040. The processor 2010 can control the output interface 2040 to communicate with other devices or chips, specifically, it can output information or data to other devices or chips.

[0485] In one possible implementation, the chip can be applied to the terminal, the first core network device, or the first access network device in the embodiments of this application, and the chip can implement the corresponding processes implemented by the terminal, the first core network device, or the first access network device in the various methods of the embodiments of this application. For simplicity, these will not be elaborated further here. It should be understood that the chip mentioned in the embodiments of this application can also be called a system-on-a-chip, system-on-a-chip, chip system, or system-on-chip, etc. The processor mentioned above can be a general-purpose processor, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or other programmable logic devices, transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor mentioned above can be a microprocessor or any conventional processor, etc. The memory mentioned above can be volatile memory or non-volatile memory, or can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM). It should be understood that the above-described memory is exemplary but not limiting. For example, the memory in the embodiments of this application can also be static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus RAM (DR RAM), etc. In other words, the memory in the embodiments of this application is intended to include, but is not limited to, these and any other suitable types of memory.

[0486] It should be understood that the sequence number of each process in the various embodiments of this application does not imply the order of execution; the execution order of each process should be determined by its function and internal logic. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. The above descriptions are merely specific embodiments of this application, and the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, comprising: The terminal receives a first message in a first radio access technology (RAT), wherein the first message is used to trigger the terminal to perform an operation related to a second RAT.

2. The method of claim 1, wherein, The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a non-access stratum NAS connection in the second RAT.

3. The method of claim 2, wherein, The first message carries at least one of the following: The type information of the second RAT, wherein the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, or the RAT corresponding to the downlink message to be transmitted; The first timer, wherein the timing duration of the first timer is one of the following: the maximum duration for which the terminal initiates or completes the establishment of a NAS connection in the second RAT, or the maximum duration for which the terminal initiates or completes the establishment of user plane resources in the second RAT.

4. The method according to claim 3, wherein after the terminal receives the first message from the first RAT, it further includes: The terminal sends a second message to the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

5. The method of claim 4, wherein, The second message is also used to establish the user plane resource corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session.

6. The method of claim 5, wherein, The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

7. The method of claim 1, wherein, The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

8. The method of claim 7, wherein, The first message carries at least one of the following: The type information of the second RAT, wherein the second RAT is the RAT corresponding to the second session that needs to be rebuilt; The identifier of the second session; The second timer, wherein the duration of the second timer is the maximum duration for which the terminal initiates or completes the reconstruction of the second session corresponding to the second RAT on the first RAT; Instructions to rebuild the second session corresponding to the second RAT on the first RAT.

9. The method according to claim 8, wherein after the terminal receives the first message from the first RAT, it further comprises one of the following: The terminal sends a service request to a first access network device corresponding to the first RAT, wherein The service request carries a third message, which is used to request that the second session corresponding to the second RAT be rebuilt in the first RAT. The terminal sends a session modification request to the first core network device through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

10. The method of claim 9, wherein, The third message carries at least one of the following: The terminal allows the identification of one or more sessions corresponding to the second RAT that can be reconstructed on the first RAT; The NAS identifier used for paging corresponds to the first RAT.

11. The method according to any one of claims 1-6, wherein, The second RAT is the same as the first RAT.

12. The method of any one of claims 1-10, wherein, The second RAT is different from the first RAT.

13. The method of any one of claims 1-12, wherein, The terminal receives a first message from the first access network device corresponding to the first RAT, including: The terminal receives a first paging message from the first access network device corresponding to the first RAT, wherein the first paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

14. The method of any one of claims 1-10, 12, wherein, The terminal receives a first message in the first RAT, including: The terminal receives a NAS notification message from the first core network device through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message.

15. The method of any one of claims 1-14, wherein, Before the terminal receives the first message from the first RAT, it also includes: The terminal sends a fourth message to the first core network device through the first access network device corresponding to the first RAT. The fourth message carries first indication information, which is used to indicate that the terminal should be managed independently under different RATs.

16. The method of claim 15, wherein, The independent multi-access connection management of the terminal under different RATs includes at least one of the following: The connection status of the terminal is managed independently under different RATs; The terminal is assigned a different NAS identifier for paging corresponding to different RATs.

17. The method of claim 15 or 16, wherein, After the terminal sends the fourth message to the first core network device through the first access network device corresponding to the first RAT, it also includes: The terminal receives a fifth message from the first core network device through the first access network device. The fifth message carries second indication information, which is used to instruct the first core network device to support independent multi-access connection management for the terminal under different RATs.

18. The method of claim 17, wherein, The fourth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

19. The method of claim 18, wherein, The fifth message carries the NAS identifier for paging corresponding to the first RAT.

20. The method of claim 17, wherein, The fourth message is used to perform a registration update in the first RAT, and the fourth message also carries the original NAS identifier for paging corresponding to the first RAT.

21. The method of claim 20, wherein, The fifth message carries the updated NAS identifier for paging corresponding to the first RAT.

22. The method of any one of claims 18-21, wherein, The fourth message also carries type information of one or more third RATs for the terminal to request independent multi-access connection management.

23. The method of claim 22, wherein, The fifth message also carries at least one of the following: The different NAS identifiers for paging correspond to different third RATs in the one or more third RATs; The type information of one or more third RATs.

24. The method of any one of claims 1-14, wherein, Before the terminal receives the first message from the first RAT, it also includes: When the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the terminal sends a sixth message to the first core network device through the first access network device corresponding to the first RAT. The sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

25. The method of claim 24, wherein, The sixth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

26. The method of claim 24 or 25, wherein, The sixth message also carries at least one of the following: The NAS identifier used for paging corresponds to the fourth RAT; The type information of the fourth RAT.

27. The method of any one of claims 24-26, wherein, After the terminal sends the sixth message to the first core network device through the first access network device corresponding to the first RAT, it also includes: The terminal receives a seventh message from the first core network device through the first access network device, wherein the seventh message carries fourth indication information, which is used to indicate that the first core network device supports allocating the same NAS identifier for paging corresponding to different RATs for the terminal.

28. The method of claim 27, wherein, The seventh message also carries at least one of the following: Type information of one or more fifth RATs; The same NAS identifier used for paging is used under one or more fifth RATs.

29. A communication method, comprising: The first core network device sends a first message to the first radio access technology (RAT), wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

30. The method of claim 29, wherein, The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a non-access stratum NAS connection in the second RAT.

31. The method of claim 30, wherein, The first message carries at least one of the following: The type information of the second RAT, wherein the second RAT is the RAT corresponding to the first session with downlink data to be transmitted, or the RAT corresponding to the downlink message to be transmitted; The first timer, wherein the timing duration of the first timer is one of the following: the maximum duration for which the terminal initiates or completes the establishment of a NAS connection in the second RAT, or the maximum duration for which the terminal initiates or completes the establishment of user plane resources in the second RAT.

32. The method according to claim 31, further comprising, after the first core network device sends the first message in the first RAT: The first core network device receives a second message sent by the terminal through the second access network device corresponding to the second RAT, wherein the second message is used to establish a NAS connection in the second RAT.

33. The method of claim 32, wherein, The second message is also used to establish the user plane resource corresponding to the second RAT for transmitting the downlink data to be transmitted in the first session.

34. The method of claim 33, wherein, The second message carries at least one of the following: a NAS identifier for paging corresponding to the second RAT, or an identifier of a session that the terminal recognizes as being allowed to be activated on the second RAT.

35. The method of claim 29, wherein, The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

36. The method of claim 35, wherein, The first message carries at least one of the following: The type information of the second RAT, wherein the second RAT is the RAT corresponding to the second session that needs to be rebuilt; The identifier of the second session; The second timer, wherein the duration of the second timer is the maximum duration for which the terminal initiates or completes the reconstruction of the second session corresponding to the second RAT on the first RAT; Instructions to rebuild the second session corresponding to the second RAT on the first RAT.

37. The method of claim 35 or 36, wherein, After the first core network device sends the first message via the first RAT, it also includes one of the following: The first core network device receives a service request through the first access network device corresponding to the first RAT, wherein the service request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; The first core network device receives a session modification request from the terminal through the first access network device corresponding to the first RAT, wherein the session modification request carries the third message.

38. The method of claim 37, wherein, The third message carries at least one of the following: The terminal allows the identification of one or more sessions corresponding to the second RAT that can be reconstructed on the first RAT; The NAS identifier used for paging corresponds to the first RAT.

39. The method of any one of claims 29-34, wherein, The second RAT is the same as the first RAT.

40. The method of any one of claims 29-38, wherein, The second RAT is different from the first RAT.

41. The method of any one of claims 29-40, wherein, The first core network device sends a first message in the first RAT, including: The first core network device sends a second paging message to the first access network device corresponding to the first RAT, wherein the second paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

42. The method of claim 41, wherein, The second paging message also carries a registration area list, wherein the registration area list is used by the first access network device to determine the cell from which the terminal is being paged.

43. The method of any one of claims 29-38, 40, wherein, The first core network device sends a first message in the first RAT, including: The first core network device sends a NAS notification message to the terminal through the first access network device corresponding to the first RAT, wherein the NAS notification message carries the first message.

44. The method of any one of claims 29-43, wherein, Before the first core network device sends the first message via the first RAT, it also includes: The first core network device receives a fourth message from the terminal through the first access network device corresponding to the first RAT. The fourth message carries first indication information, which is used to indicate that the terminal should be managed independently under different RATs.

45. The method of claim 44, wherein, The independent multi-access connection management of the terminal under different RATs includes at least one of the following: The connection status of the terminal is managed independently under different RATs; The terminal is assigned a different NAS identifier for paging corresponding to different RATs.

46. The method of claim 44 or 45, wherein, After the first core network device receives the fourth message from the terminal through the first access network device corresponding to the first RAT, it further includes: The first core network device sends a fifth message to the terminal through the first access network device. The fifth message carries second indication information, which is used to instruct the first core network device to support independent multi-access connection management for the terminal under different RATs.

47. The method of claim 46, wherein, The fourth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

48. The method of claim 47, wherein, The fifth message carries the NAS identifier for paging corresponding to the first RAT.

49. The method of claim 46, wherein, The fourth message is used to perform a registration update in the first RAT, and the fourth message also carries the original NAS identifier corresponding to the first RAT for paging.

50. The method of claim 49, wherein, The fifth message carries the updated NAS identifier for paging corresponding to the first RAT.

51. The method of any one of claims 47-50, wherein, The fourth message also carries type information of one or more third RATs for the terminal to request independent multi-access connection management.

52. The method of claim 51, wherein, The fifth message also carries at least one of the following: The different NAS identifiers for paging correspond to different third RATs in the one or more third RATs; The type information of one or more third RATs.

53. The method of any one of claims 29-43, wherein, Before the first core network device sends the first message via the first RAT, it also includes: When the terminal establishes a fourth NAS connection under the fourth RAT with the third core network device through the third access network device corresponding to the fourth RAT, the first core network device receives a sixth message from the terminal through the first access network device corresponding to the first RAT. The sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

54. The method of claim 53, wherein, The sixth message is used by the terminal to establish a first NAS connection under the first RAT between the first access network device and the first core network device.

55. The method of claim 53 or 54, wherein, The sixth message also carries at least one of the following: The NAS identifier used for paging corresponds to the fourth RAT; The type information of the fourth RAT.

56. The method of any one of claims 53-55, wherein, After the first core network device receives the sixth message from the terminal through the first access network device corresponding to the first RAT, it further includes: The first core network device sends a seventh message to the terminal through the first access network device. The seventh message carries fourth indication information, which is used to indicate that the first core network device supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs.

57. The method of claim 56, wherein, The seventh message also carries at least one of the following: Type information of one or more fifth RATs; The same NAS identifier used for paging is used under one or more fifth RATs.

58. A communication method, comprising: The first access network device receives a first message from the first core network device, wherein the first access network device corresponds to a first radio access technology (RAT), and the first message is used to trigger the terminal to perform an operation related to the second RAT. The first access network device sends the first message to the terminal.

59. The method of claim 58, wherein, The step of triggering the terminal to perform operations related to the second RAT includes: triggering the terminal to establish a non-access stratum NAS connection in the second RAT.

60. The method of claim 58, wherein, The step of triggering the terminal to perform an operation related to the second RAT includes: triggering the terminal to rebuild the second session corresponding to the second RAT on the first RAT.

61. The method according to claim 60, further comprising, after the first access network device sends the first message to the terminal: The first access network device receives a service request from the terminal, wherein the service request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; The first access network device sends the service request to the first core network device.

62. The method according to claim 60, further comprising, after the first access network device sends the first message to the terminal: The first access network device receives a session modification request from the terminal, wherein the session modification request carries a third message, the third message being used to request that the second session corresponding to the second RAT be rebuilt in the first RAT; The first access network device sends the session modification request to the first core network device.

63. The method of claim 58 or 59, wherein, The second RAT is the same as the first RAT.

64. The method of any one of claims 58-62, wherein, The second RAT is different from the first RAT.

65. The method of any one of claims 58-64, wherein, The first access network device receives a first message from the first core network device, including: The first access network device receives a second paging message from the first core network device, wherein the second paging message carries the first message, and the first message carries the NAS identifier for paging corresponding to the first RAT.

66. The method of claim 65, wherein, The second paging message also carries a registration area list, wherein the registration area list is used by the first access network device to determine the cell from which the terminal is being paged.

67. The method of claim 65 or 66, wherein, The first access network device sends the first message to the terminal, including: The first access network device sends a first paging message to the terminal, wherein the first paging message carries the first message.

68. The method of any one of claims 58-62, 64, wherein, The first access network device receives a first message from the first core network device, including: the first access network device receives a NAS notification message from the first core network device, wherein the NAS notification message carries the first message; The first access network device sends the first message to the terminal, including: the first access network device sending the NAS notification message to the terminal.

69. The method of any one of claims 58-68, wherein, Before the first access network device receives the first message from the first core network device, it also includes: The first access network device sends a fourth message from the terminal to the first core network device, wherein the fourth message carries first indication information, which is used to indicate that the terminal should be managed independently under different RATs.

70. The method of claim 69, wherein, After the first access network device sends the fourth message from the terminal to the first core network device, it further includes: The first access network device sends a fifth message from the first core network device to the terminal, wherein the fifth message carries second indication information, which is used to indicate that the first core network device supports independent multi-access connection management for the terminal under different RATs.

71. The method of any one of claims 58-68, wherein, Before the first access network device receives the first message from the first core network device, it also includes: The first access network device sends a sixth message from the terminal to the first core network device, wherein the sixth message carries third indication information, which is used to indicate that the terminal is assigned the same NAS identifier for paging corresponding to different RATs.

72. The method of claim 71, wherein, After the first access network device sends the sixth message from the terminal to the first core network device, it further includes: The first access network device sends a seventh message from the first core network device to the terminal, wherein the seventh message carries fourth indication information, which is used to indicate that the first core network device supports assigning the same NAS identifier for paging to the terminal corresponding to different RATs.

73. A terminal, comprising: The first communication unit is configured to receive a first message in a first radio access technology (RAT), wherein the first message is configured to trigger the terminal to perform an operation related to a second RAT.

74. A first core network device, comprising: The second communication unit is configured to send a first message using a first wireless access technology (RAT), wherein the first message is used to trigger the terminal to perform an operation related to the second RAT.

75. A first access network device, comprising: The third communication unit is configured to receive a first message from a first core network device, wherein the first access network device corresponds to a first radio access technology (RAT), and the first message is configured to trigger the terminal to perform an operation related to a second RAT; and to send the first message to the terminal.

76. A terminal comprising: A transceiver, a processor, and a memory for storing a computer program, the transceiver for communicating with other devices, and the processor for calling and running the computer program stored in the memory to cause the terminal to perform the method as described in any one of claims 1 to 28.

77. A first core network device, comprising: A transceiver, a processor, and a memory for storing computer programs, the transceiver for communicating with other devices, and the processor for calling and running the computer programs stored in the memory to cause the first core network device to perform the method as described in any one of claims 29 to 57.

78. A first access network device, comprising: A transceiver, a processor, and a memory for storing a computer program, the transceiver for communicating with other devices, and the processor for calling and running the computer program stored in the memory to cause the first access network device to perform the method as described in any one of claims 58 to 72.

79. A chip comprising: A processor for retrieving and running a computer program from memory, causing a device having the chip mounted to perform the method as described in any one of claims 1 to 28, or claims 29 to 57, or claims 58 to 72.

80. A computer-readable storage medium for storing a computer program that, when run by a device, causes the device to perform the method as described in any one of claims 1 to 28, or claims 29 to 57, or claims 58 to 72.

81. A computer program product comprising computer program instructions that cause a computer to perform the method as described in any one of claims 1 to 28, or claims 29 to 57, or claims 58 to 72.

82. A computer program that causes a computer to perform the method as described in any one of claims 1 to 28, or claims 29 to 57, or claims 58 to 72.

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