Communication method, communication device, medium and program product

Abstract

The embodiment of the invention provides a communication method, communication equipment, a computer readable storage medium and a computer program product. In the communication method, a terminal device receives a connection release message from a first network device, the connection release message comprising identification information of the terminal device allocated by the first network device. The terminal device receives broadcast information from the second network device, the broadcast information including identification information of the terminal device allocated by the first network device. And the terminal device determines to access the second network device based on the identification information and the broadcast information. In this way, the terminal device can access the second network device without executing an initial access process with the second network device, thereby reducing time delay.

Description

Technical Field

[0001] This disclosure generally relates to the field of communications, and more specifically to a communication method, communication device, computer-readable storage medium, and computer program product. Background Art

[0002] With the development of communication technology, non-terrestrial networks (NTNs) are being researched to further improve coverage and provide communication services to areas such as oceans and forests. NTNs refer to networks or network segments that utilize radio frequency resources from satellites or high-altitude platform stations. Unlike terrestrial base stations, network equipment acting as base stations in NTNs moves at relatively high speeds relative to the ground and travels longer distances, resulting in greater signal path loss. Current communication mechanisms designed for terminal devices and terrestrial base stations in mobile communication systems cannot be directly applied to NTN systems.

[0003] In NTN communication systems, the NTN payload and NTN gateway provide non-terrestrial New Radio (NR) access to User Equipment (UE). Store & Forward (S&F) operations are proposed for latency-tolerant services. However, some issues remain to be resolved for NTN communication systems. Summary of the Invention

[0004] Embodiments of this application provide a communication method, a communication device, and a computer-readable storage medium.

[0005] In a first aspect of this application, a communication method is provided. A terminal device receives a connection release message from a first network device, the connection release message including identification information of the terminal device assigned by the first network device. The terminal device receives broadcast information from a second network device, the broadcast information including the identification information of the terminal device assigned by the first network device. Based on the identification information and the broadcast information, the terminal device determines whether to access the second network device. In this way, the terminal device can access the second network device without performing an initial access procedure with the second network device, thereby reducing access latency.

[0006] In some embodiments, the identification information may further include a list of device identifiers of at least one network device having the context of the terminal device, the broadcast information includes the device identifier of the second network device, and determining access to the second network device includes: determining that the list of device identifiers includes the device identifier of the second network device. Thus, the terminal device can access the second network device based on the device identifier of the second network device without performing an initial access procedure.

[0007] In some embodiments, the connection release message may further include timer information, wherein the terminal device is prohibited from accessing the network device during the timer's execution. This avoids the terminal device performing unnecessary access procedures with other network devices. In some embodiments, the connection release message may further include a first indication, which instructs the terminal device to add identification information. This enables the terminal device to obtain identification information, thereby reducing signaling overhead.

[0008] In some embodiments, the connection release message received from the first network device is a first connection release message, and the terminal device may also receive a second connection release message from the second network device. The second connection release message includes a second indication, which instructs the terminal device to delete at least one of its context or identification information. Thus, the state information between the terminal device and the network side is synchronized.

[0009] In some embodiments, before receiving a connection release message, the terminal device receives a data packet from the first network device. The connection release message may further include: first sequence number information, a third indication, or a combination of both. The first sequence number information indicates the sequence number of a successfully transmitted data packet, and the third indication instructs the terminal device to send second sequence number information to the second network device. The second sequence number information includes the first sequence number information or the sequence number of a successfully transmitted data packet determined by the terminal device, or both. Thus, the sequence number of the successfully transmitted data packet can be indicated to the second network device.

[0010] In some embodiments, the terminal device can also access the second network device via a connection restoration message. This eliminates the need for the terminal device to access the second network device via an initial access procedure, reducing access latency. In some embodiments, the terminal device can also send a second sequence number to the second network device. This allows the second network device to transmit data packets based on already successfully transmitted packets, avoiding duplicate transmission of data packets.

[0011] In a second aspect of this application, a communication method is provided. A first network device decides to release a terminal device into an inactive state. A second network device sends the context of the terminal device to a core network device and sends a connection release message to the terminal device, the connection release message including the identification information of the terminal device assigned by the first network device. In this way, the context of the terminal device can be pushed to subsequent network devices, thereby enabling the terminal device to access subsequent network devices more quickly.

[0012] In some embodiments, before releasing the terminal device, the first network device sends a data packet to the terminal device. The connection release message may also include first sequence number information or a third indication, or a combination of both. The first sequence number information indicates the sequence number of a successfully transmitted data packet. The third indication is used to instruct the terminal device to send second sequence number information to the second network device. The second sequence number information may include: the first sequence number information, the sequence number of a successfully transmitted data packet determined by the terminal device, or a combination of both. Thus, the sequence number of a successfully transmitted data packet can be indicated to the second network device, avoiding duplicate transmission of the data packet.

[0013] In some embodiments, before releasing the terminal device, the first network device sends a data packet to the terminal device. The first network device may also send first sequence number information to the core network device. The sequence number information of the first data packet indicates a data packet that has been successfully transmitted. Thus, the sequence number of the successfully transmitted data packet can be indicated to the second network device, avoiding duplicate transmission of the data packet.

[0014] In some embodiments, before releasing the terminal device, the first network device sends data packets to the terminal device. The first network device may also send a number associated with the data packet transmission status to the core network device. Thus, data transmission continuity can be guaranteed.

[0015] In a third aspect of this application, a communication method is provided. A second network device receives from a core network device identification information and a context of a terminal device assigned by a first network device. The second network device then sends broadcast information, which includes the identification information of the terminal device assigned by the first network device. In this manner, the terminal device can access the second network device without performing an initial access procedure with the second network device, thereby reducing access latency.

[0016] In some embodiments, based on determining that data transmission between the second network device and the terminal device is complete, the second network device may send a fourth indication to the core network device. This fourth indication instructs the core network device to notify at least one network device possessing the context of the terminal device to delete at least one of the terminal device's context or identification information. The second network device may also send a connection release message to the terminal device, the connection release message including a second indication instructing the terminal device to delete the identification information. Thus, the state information between the terminal device side and the network side is synchronized.

[0017] In some embodiments, the second network device and the terminal device perform downlink transmission. The second network device can also receive from the terminal device the sequence number of data packets successfully transmitted by the first network device. The sequence number of data packets successfully transmitted by the first network device can be carried via a connection recovery message. In some embodiments, the second network device can also receive the sequence number of data packets successfully transmitted by the first network device from the core network device. Thus, the sequence number of successfully transmitted data packets can be indicated to the second network device.

[0018] In some embodiments, the second network device can also perform data transmission based on the sequence number of data packets that have already been successfully transmitted by the first network device, thereby avoiding duplicate transmission of data packets. In some embodiments, the second network device performs downlink transmission with the terminal device, and the second network device can also receive first data from the core network device, the first data being data that the first network device failed to transmit; send the first data to the terminal device; and send the second data received from the core network device to the terminal device. This ensures the continuity of data transmission.

[0019] In a fourth aspect of this application, a communication method is provided. A core network device sends the identification information of a terminal device, allocated by a first network device, and the context of the terminal device to a second network device. The second network device then serves the terminal device in a second time period following a first time period. In this manner, the context of the terminal device can be pushed to subsequent network devices, allowing the terminal device to access subsequent network devices more quickly.

[0020] In some embodiments, before sending the context of the terminal device, the core network device can receive, from the first network device, identification information of the terminal device and an identifier of the terminal device's context, assigned by the first network device. Therefore, the core network device can push the identification information of the terminal device and the identifier of the terminal device's context to other network devices.

[0021] In some embodiments, the second network device and the terminal device perform downlink transmission. The core network device can also receive sequence number information of data packets from the first network device. The sequence number information of the data packets indicates data packets that have been successfully transmitted by the first network device. The core network device can send the sequence number information of the data packets to the second network device. Thus, the sequence number of successfully transmitted data packets can be indicated to the second network device.

[0022] In some embodiments, the second network device and the terminal device perform downlink transmissions, and the core network device can also receive data packets that were not successfully transmitted by the first network device. The core network device can then send the data packets that were not successfully transmitted by the first network device to the second network device, thereby ensuring the continuity of data transmission.

[0023] In some embodiments, the second network device and the terminal device perform downlink transmissions, and the core network device can also receive a number associated with the packet transmission status from the first network device. Based on the number, the core network device can download packets that were not successfully transmitted by the first network device. The core network device can then send the packets that were not successfully transmitted by the first network device to the second network device, thereby ensuring the continuity of data transmission.

[0024] In some embodiments, the core network device may also receive a fourth instruction from the second network device, the fourth instruction instructing the core network device to notify at least one network device having the context of the terminal device to delete at least one of the terminal device's context or identification information. The core network device may then send a fifth instruction to the at least one network device, the fifth instruction instructing the at least one network device to delete the first identifier. Thus, the state information between the terminal device side and the network side is synchronized.

[0025] In a fifth aspect of this application, a communication device is provided. The communication device includes a processor and a memory storing instructions. When executed by the processor, the instructions cause the communication device to perform any method according to any one of the first to fourth aspects and their implementations.

[0026] In a sixth aspect of this application, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions that, when executed by an electronic device, cause the electronic device to perform any method of any one of the first to fourth aspects and their implementations.

[0027] In a seventh aspect of this application, a chip is provided. The chip includes processing circuitry configured to perform any method of any one of the first to fourth aspects and their implementations.

[0028] In an eighth aspect of this application, a computer program product is provided. The computer program product includes instructions that, when executed by an electronic device, cause the electronic device to perform any method of any one of the first to fourth aspects and their implementations.

[0029] It should be understood that the description in the Summary Section is not intended to limit the key or essential features of this application, nor is it intended to restrict the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0030] Figure 1A A schematic diagram of a communication system in which embodiments of the present disclosure may be implemented is shown.

[0031] Figure 1BA schematic diagram of the base station-side NR protocol stack and network element modules related to embodiments of this disclosure is shown.

[0032] Figure 1C A schematic diagram of an open radio access network (O-RAN) architecture related to embodiments of the present disclosure is shown.

[0033] Figure 1D A schematic diagram of an NTN scenario related to embodiments of this disclosure is shown.

[0034] Figure 1E A schematic diagram of a store-and-forward scenario related to embodiments of the present disclosure is shown.

[0035] Figure 1F A schematic flowchart of UE access in relation to embodiments of this disclosure is shown.

[0036] Figure 1G A schematic flowchart relating to user authentication and authorization in connection with embodiments of this disclosure is shown.

[0037] Figure 2 Interactive signaling diagrams according to some embodiments of this disclosure are shown.

[0038] Figure 3 A time-domain schematic diagram illustrating the access performed by a terminal device and a network device according to some embodiments of the present disclosure is shown.

[0039] Figure 4 A schematic diagram of several satellite storage files according to some embodiments of the present disclosure is shown.

[0040] Figure 5 A first example process according to some embodiments of this disclosure is shown.

[0041] Figure 6 A second example process according to some embodiments of this disclosure is shown.

[0042] Figure 7 A schematic flowchart illustrating a method implemented at a terminal device according to an embodiment of the present disclosure is shown.

[0043] Figure 8 A schematic flowchart of a method implemented at a first network device according to an embodiment of the present disclosure is shown.

[0044] Figure 9 A schematic flowchart of a method implemented at a second network device according to an embodiment of the present disclosure is shown.

[0045] Figure 10 A schematic flowchart illustrating a method implemented at a core network device according to an embodiment of the present disclosure is shown.

[0046] Figure 11 This is a block diagram of a device that can be used to implement some embodiments of this application.

[0047] Figure 12 This is a schematic diagram of the structure of an apparatus according to some embodiments of this application.

[0048] Figure 13 This is a schematic diagram of the structure of an apparatus according to some embodiments of this application.

[0049] Figure 14 This is a schematic diagram of the structure of an apparatus according to some embodiments of this application.

[0050] Figure 15 This is a schematic diagram of the structure of an apparatus according to some embodiments of this application.

[0051] Throughout all the accompanying drawings, the same or similar reference numerals are used to denote the same or similar components. Detailed Implementation

[0052] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0053] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0054] Embodiments of this disclosure may be implemented according to any suitable communication protocol, including but not limited to cellular communication protocols such as 3rd generation (3G), 4th generation (4G), 5th generation (5G) and future communication protocols (e.g., 6th generation (6G)), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol currently known or to be developed in the future.

[0055] The technical solutions of the embodiments disclosed herein are applicable to communication systems that follow any suitable communication protocol, such as: General Packet Radio Service (GPRS), Global System for Mobile Communications (GSM), Enhanced Datarate for GSM Evolution (EDGE), Universal Mobile Telecommunications Service (UMTS), Long Term Evolution (LTE) systems, Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access 2000 (CDMA2000), Time Division-Synchronization Code Division Multiple Access (TD-SCDMA), Frequency Division Duplex (FDD) systems, Time Division Duplex (TDD), fifth-generation (5G) systems (e.g., New Radio (NR)), and future communication systems (e.g., sixth-generation (6G) systems), etc.

[0056] For illustrative purposes, embodiments of this disclosure are described below with reference to 5G communication systems within the 3rd Generation Partnership Project (3GPP). However, it should be understood that embodiments of this disclosure are not limited to this communication system, but can be applied to any communication system with similar problems, such as wireless local area networks (WLANs), wired communication systems, or other communication systems developed in the future.

[0057] As used in this disclosure, the terms "network node" or "network device" refer to an entity or node that can be used to communicate with a terminal device, such as an access network device. An access network device can be a means deployed in a radio access network to provide wireless communication functionality for a mobile terminal, such as a Radio Access Network (RAN) network device. Access network devices can include various types of base stations. Base stations are used to provide radio access services to terminal devices. Specifically, each base station corresponds to a service coverage area, and terminal devices entering this area can communicate with the base station via wireless signals to receive the radio access services provided by the base station. The service coverage areas of base stations may overlap, and terminal devices in overlapping areas can receive wireless signals from multiple base stations, thus allowing multiple base stations to provide services to the terminal device simultaneously. Depending on the size of the provided service coverage area, access network devices can include macro base stations providing macro cells, micro base stations providing pico cells, pico base stations providing pico cells, and femto base stations providing femto cells. In addition, access network equipment can also include various forms of relay stations, access points, remote radio units (RRUs), radio heads (RHs), remote radio heads (RRHs), and so on. The names of access network equipment may differ in systems employing different radio access technologies; for example, in Long Term Evolution (LTE) networks it is called an evolved Node B (eNB or eNodeB), in 3G networks it is called a Node B (NB), and in 5G networks it may be called a g Node B (gNB) or NR Node B (NR NB), and so on. In some implementations, access network equipment can include satellites or high-altitude platform stations, and can be applied to scenarios such as Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geostationary Earth Orbiting (GEO) / Unmanned Aircraft System (UAS). For ease of description, in the subsequent embodiments of this disclosure, the devices that provide wireless communication functions for mobile terminals are collectively referred to as network devices, and the embodiments of this disclosure are no longer specifically limited.

[0058] Figure 1A A schematic diagram of a communication system 100 that can be implemented according to an embodiment of this disclosure is shown. For example... Figure 1AAs shown, the communication system includes a Radio Access Network (RAN) 101, a Core Network (CN) 102, and the Internet 103. RAN 101 includes at least one RAN node (e.g., Figure 1A 110a and 110b (collectively referred to as 110) and at least one terminal (such as Figure 1A 120a-120j, collectively referred to as 120, are included in the RAN. The RAN may also include other RAN nodes, such as wireless relay devices and / or wireless backhaul devices. Figure 1A (Not shown in the image). Terminal 120 is connected to RAN node 110 wirelessly. RAN node 110 is connected to core network 102 wirelessly or via wired connection. The core network equipment in core network 102 and RAN node 110 in RAN 101 can be different physical devices, or they can be the same physical device integrating core network logical functions and radio access network logical functions.

[0059] RAN 101 can be a 3GPP-related cellular system, such as a 4G or 5G mobile communication system, an NTN system, or a future-oriented evolution system (such as a 6G mobile communication system). RAN 101 can also be an open access network (open RAN, O-RAN, or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system, or a communication system that integrates two or more of the above systems.

[0060] In this disclosure, RAN 101 is an NTN system. RAN 101 can be in transparent mode or regeneration mode, or an Earth Fixed Cell or an Earth Moving Cell.

[0061] The network elements primarily involved in this disclosure include terminal 120, RAN node 110, and core network equipment 102. Terminal 120 can also be referred to as terminal equipment, user equipment (UE), remote station, remote terminal, mobile device, UE terminal, terminal, wireless communication equipment, multimedia equipment, streaming media equipment, UE agent, or UE device, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. The access terminal can be a cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA), handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, in-vehicle device, wearable device, terminal in a future 5G network, or terminal in a future evolved public land mobile network (PLMN) network, etc. The embodiments of this application do not limit the device form of the terminal.

[0062] RAN node 110, sometimes also referred to as access network equipment, RAN entity, or access node, constitutes part of the communication system and assists terminals in achieving wireless access. Multiple RAN nodes 110 in communication system 100 can be of the same type or different types. In some scenarios, the roles of RAN node 110 and terminal 120 are relative, for example... Figure 1A Network element 120i can be a helicopter or a drone, and it can be configured as a mobile base station. For terminals 120j accessing RAN 100 via network element 120i, network element 120i is a base station. However, for base station 110a, network element 120i is a terminal. RAN node 110 and terminal 120 are sometimes referred to as communication devices, for example... Figure 1ANetwork elements 110a and 110b can be understood as communication devices with base station functions, while network elements 120a-120j can be understood as communication devices with terminal functions.

[0063] Communication between access network devices and terminal devices follows a specific protocol layer structure. This protocol layer may include a control plane protocol layer and a user plane protocol layer. The control plane protocol layer may include at least one of the following: Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, or Physical (PHY) layer, etc. The user plane protocol layer may include at least one of the following: Service Data Adaptation Protocol (SDAP) layer, PDCP layer, RLC layer, MAC layer, or Physical layer, etc.

[0064] In one possible scenario, a RAN node can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a next-generation base station in a 6th generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system, etc. A RAN node can also be a macro base station (such as...) Figure 1A 110a), micro base stations or indoor stations (such as Figure 1A In CRAN scenarios, the RAN node can be a relay node or donor node (e.g., 110b), or a wireless controller. Alternatively, the RAN node can also be a server, wearable device, vehicle, or in-vehicle equipment. For example, in Vehicle to Everything (V2X) technology, the access network equipment can be a Roadside Unit (RSU).

[0065] In another possible scenario, multiple RAN nodes collaborate to assist the terminal in achieving wireless access, with different RAN nodes each implementing some of the base station's functions. For example, RAN nodes can be Central Units (CUs), Distributed Units (DUs), CUs (Control Plane, CPs), CUs (User Plane, UPs), or Radio Units (RUs), etc. CUs and DUs can be set up separately or included in the same network element, such as the Baseband Unit (BBU). The CU and DU nodes separate the gNB's protocol layers; some protocol layer functions are centrally controlled by the CU, while the remaining partial or complete protocol layer functions are distributed in the DU, which is centrally controlled by the CU. Figure 1B A schematic diagram of the base station-side NR protocol stack and network element modules related to embodiments of this disclosure is shown. Figure 1B As shown, in one implementation, the CU deploys the Radio Resource Control (RRC) layer, PDCP layer, and Service Data Adaptation Protocol (SDAP) layer in the protocol stack. The DU deploys the Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical Layer (PHY) in the protocol stack. Thus, the CU has the processing capabilities for RRC, PDCP, and SDAP. The DU has the processing capabilities for RLC, MAC, and PHY. It is understood that the above functional division is merely an example and does not constitute a limitation on the CU and DU. The RU can be included in radio frequency equipment or radio frequency units, such as in a Remote Radio Unit (RRU), Active Antenna Unit (AAU), or Remote Radio Head (RRH).

[0066] Core network equipment refers to the equipment in the core network that provides service support to terminals. Examples of core network equipment include: Access and Mobility Management Function (AMF) entities, Session Management Function (SMF) entities, User Plane Function (UPF) entities, etc., which will not be listed here. The AMF entity is responsible for terminal access management and mobility management. The SMF entity is responsible for session management, such as user session establishment. The UPF entity can be a user plane functional entity, mainly responsible for connecting to external networks. It should be noted that in this application, entities can also be referred to as network elements or functional entities. For example, an AMF entity can also be called an AMF network element or an AMF functional entity, and an SMF entity can also be called an SMF network element or an SMF functional entity, etc.

[0067] Core network equipment can correspond to different devices in different systems. For example, in 3G, core network equipment can correspond to the Serving GPRS Support Node (SGSN) and / or the Gateway GPRS Support Node (GGSN) for General Packet Radio Service (GPRS). In 4G, core network equipment can correspond to the Mobility Management Entity (MME) and / or the Serving Gateway (S-GW). In 5G, core network equipment can correspond to the Access and Mobility Management Function (AMF), Session Management Function (SMF), or User Plane Function (UPF).

[0068] O-RAN aims to achieve an intelligent and open access network. A key feature of the O-RAN architecture is the separation of hardware and software, enabling the virtualization of network functions and the standardization of hardware. Furthermore, O-RAN incorporates Artificial Intelligence (AI).

[0069] In the ORAN system, CU can also be called Open CU (O-CU), DU can also be called Open DU (O-DU), CU-CP can also be called Open CU-CP (O-CU-CP), CU-UP can also be called Open CU-UP (O-CU-UP), and RU can also be called Open RU (O-RU). In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0070] Figure 1C A schematic diagram of the O-RAN architecture related to embodiments of this disclosure is shown. As shown, apart from the interface with the network management subsystem, O-RAN does not change the interfaces of existing logical network elements such as F1, E1, X2, Xn, and NG defined by 5G 3GPP, but adds new interfaces on this basis: O1, O2, A1, and E2.

[0071] The table below shows the correspondence between ORAN access network equipment (network element modules) and their implemented protocol layer functions:

[0072]

[0073]

[0074] In NTN communication systems, a non-geosynchronous orbit (NGSO) refers to an orbit centered on the Earth whose period does not match the Earth's rotation. This includes LEO and MEO. LEO operates at altitudes between 300 and 1500 kilometers, while MEO operates at altitudes between approximately 7000 and 25000 kilometers. A geosynchronous orbit (GEO) is an orbit centered on the Earth, located approximately 35,786 kilometers above the Earth's surface, and synchronized with the Earth's rotation. A geostationary orbit is a non-inclined geosynchronous orbit, located within the Earth's equatorial plane. The non-terrestrial network (Non-Geosynchronous-RAN, NG-RAN) is composed of gNBs (gNBs) that provide non-terrestrial NR access to UEs via NTN payloads and NTN gateways on airborne or spaceborne NTN carriers. The NTN gateway is a ground station located on the Earth's surface, providing connectivity to the NTN payload through a feeder link. An NTN gateway is a Transport Network Layer (TNL) node.

[0075] An NTN payload is a network node carried on a satellite or high-altitude platform station, providing connectivity between the service link and the feeder link. An NTN payload can be a TNL node. A feeder link is the radio link between the NTN gateway and the NTN payload. A service link is the radio link between the NTN payload and the UE.

[0076] Figure 1D A schematic diagram of an NTN scenario related to embodiments of this disclosure is shown. Figure 1D This illustrates an NTN network providing non-terrestrial NR access to the UE via the NTN payload and NTN gateway, the service link between the NTN payload and the UE, and the feeder link between the NTN gateway and the NTN payload. Figure 1D As shown, the NTN payload forwards the radio protocol received by the UE (via the serving link) to the NTN gateway (via the feeder link), and vice versa.

[0077] One NTN gateway can serve multiple NTN payloads; one NTN payload can be served by multiple NTN gateways. Currently, three types of service links are supported:

[0078] - Earth-fixed: Provided by a beam, it continuously covers the same geographical area (e.g., in the case of geostationary orbit satellites);

[0079] - Quasi-fixed: Provided by (multiple) beams, covering a geographic area for a limited time and a different geographic area for another time (e.g., the case of NGSO satellites generating steerable beams);

[0080] - Earth Motion: Provided by a beam that slides across the Earth's surface over a coverage area (e.g., in cases where NGSO satellites generate fixed or non-steerable beams).

[0081] Using NGSO satellites, gNBs can provide quasi-Earth fixed service links or Earth mobile service links, while gNBs operating using non-Geosynchronous orbit (GSO) satellites can provide Earth fixed service links.

[0082] In Release 19 (R19), store-and-forward satellite operations were proposed for latency-tolerant services, such as data transmission supporting IoT-NTN. Figure 1E A schematic diagram of a store-and-forward scenario related to embodiments of this disclosure is shown. For example... Figure 1E As shown, SAT-RAN1 110-1 flies over the area where UE 120 is located for a certain period of time (e.g., T11-T12) to provide services, such as storing signaling or data sent by UE. When SAT-RAN1 110-1 flies over the ground gateway station 110-2 (e.g., T13), it hands over the stored UE signaling or data to the gateway station for transmission to the core network 102 and even the server.

[0083] UE 120 can be served by S&F satellites, such as SAT-RAN1 110-1 and SAT-RAN2 110-2. Assuming that both SAT-RAN1 110-1 and SAT-RAN2 110-2 are NGSO satellites, they can only serve the UE in that area for a limited time. The service duration and period are related to the satellite orbit and the Earth's rotation. Assuming the UE performs data transmission after accessing SAT-RAN1 110-1 between T11 and T12, and SAT-RAN2 110-2 moves away at T12, then SAT2 110-2 moves in at T21.

[0084] At this point, if UE 120 uses the following initial access procedure to access SAT-RAN2 110-2, at least two cycles are required. Figure 1F A schematic flowchart illustrating UE access related to embodiments of this disclosure is shown. In mobile communication systems, taking LTE or NR terrestrial networks as examples, the process of UE accessing a base station mainly includes the following steps: Figure 1F The diagram shows the RRC signaling establishment process, the NAS interactive authentication / authorization / registration process, and the initial context establishment process.

[0085] The prerequisites for a UE's initial successful access are: the UE is within the coverage area of ​​the base station; the S1 / NG link between the base station and the core network is in normal condition, and the base station and the core network can exchange UE signaling in a timely manner; and the signaling between the UE and the base station, and between the base station and the core network, is completed before the timer expires.

[0086] The UE first initiates the RACH procedure with the base station. The UE sends msg1, the preamble, to the base station. The base station sends msg2, which is the reply to the RAR and the allocation of temp-CRNTI. The UE then sends msg3, the RRC Setup Request, to the base station. msg3 carries the UE identity, such as a random value, the Temporary Mobile Subscriber Identity (TMSI), and the RRC setup reason value.

[0087] The base station replies to the UE with msg4, i.e., RRC Setup, to establish an SRB1 bearer and obtain the C-RNTI identifier. The UE sends msg5 to the base station: RRC Setup Complete, carrying the selectedPLMN-Identity and dedicatedInfoNAS information elements. The RRC signaling between the UE and the base station is successfully established. When the UE sends msg5 with the NAS, it starts a NAS timer. After the timer expires, the UE will re-initiate access.

[0088] After receiving msg5 from the UE, the base station initiates an Initial UE message to the core network. This message includes ran-UE-NGAP-ID, NAS PDU, user location information, and an initial context request indication. The UE and core network then initiate authentication, NAS encryption, and registration procedures. As long as the interface link between the base station and the core network is normal, the core network and UE communicate via uplink and downlink NAS messages through the base station to complete NAS layer authentication, encryption, and registration. Figure 1G As shown. The NAS PDU carried by the core network in the DL NAS TRANSP message can be authentication, NAS encryption, and registration messages, etc.

[0089] There are two possible methods for the core network to issue NAS (Access Attached) messages. In Method 1, authentication (i.e., the authentication request AUTHREQ and the authentication response AUTH RES) is completed first, followed by the exchange of two NAS messages (downlink and uplink). Then, NAS encryption (i.e., two NAS messages, MM_SECU_CMD and MM_SECU_CMP) is initiated, and finally, a registration request is completed (i.e., two NAS messages, REG ACP and REGCMP). The core network includes the UE's Tracking Area List (TA) in the REG ACP NAS message. In Method 2, after receiving the initial UE message, the core network sends at least three downlink NAS messages in parallel for authentication, encryption, and registration, respectively. The base station then transmits these three messages to the UE. The UE processes each of the three NAS messages based on the received NAS. If any NAS message fails to process, the UE access fails; if all three NAS messages are successfully exchanged, the UE access is successful. Compared to Method 1, Method 2 does not wait for the processing results of the previous steps, allowing for parallel processing and shorter access latency.

[0090] Continue to refer to Figure 1F The core network sends an Initial Context Setup Request message to the base station to establish the necessary overall initial context for the UE. Upon receiving the Initial Context Setup Response message, the base station begins establishing the context with the UE. Simultaneously, the base station performs security configuration, generating keys for service bearers and signaling based on the received security parameters. The base station notifies the UE to initiate integrity protection and encryption processes via a Security Mode command. Downlink encryption has already begun at this point. The base station then sends an encrypted and integrity-protected RRC Connection Reconfiguration message for the establishment of SRB2 and DRB.

[0091] The UE selects the encryption algorithm indicated by the base station according to the Security mode command message and generates a key used by both the service bearer and the signaling plane. After successful key generation, the UE sends a Security mode complete message to the base station. The UE establishes a connection by completing RRC connection reconfiguration and, upon successful connection establishment, replies with an RRC connection reconfiguration complete message to the base station. The base station then replies with an Initial context setup response message to the core network.

[0092] As mentioned above, if the UE accesses SAT-RAN2 110-2, a new UE context establishment is required, which is time-consuming. If the UE does not access SAT-RAN2 110-2 and chooses to wait for SAT-RAN1 110-1, the coverage provided by SAT-RAN2 110-2 may be wasted. Therefore, the UE needs to determine whether to access another satellite for data transmission.

[0093] In view of this, embodiments of the present disclosure provide a communication method. In this method, a terminal device receives identification information of the terminal device assigned by a first network device. The terminal device receives broadcast information from a second network device, the broadcast information including the identification information of the terminal device assigned by the first network device. Based on the identification information and the broadcast information, the terminal device determines to access the second network device. In this manner, the terminal device can access the second network device without performing an initial access procedure with the second network device, thereby reducing latency.

[0094] Figure 2 The illustration shows interactive signaling diagrams according to some embodiments of the present disclosure. For clarity of explanation and without any limitation, process 200 will be combined with... Figure 1A Let's discuss this further.

[0095] In process 200, the first network device 110-1 decides 205 to release the terminal device 120 into an inactive state. In the context of this application, the inactive state can also be referred to as a deactivated state. In some scenarios, such as NTN communication, the terminal device may need to connect to multiple network devices (e.g., satellites) for data transmission. Figure 3A time-domain schematic diagram illustrating the access process between a UE and a terminal device according to some embodiments of this disclosure is shown. As shown, the terminal device first accesses Sat1 (i.e., the first network device 110-1) at time T11 to perform uplink data transmission. The data can be transmitted until time T12, which is the end time of Sat1's service. After Sat1's service ends, it will send a connection release message to the terminal device 120.

[0096] Continue to refer to Figure 2 The first network device 110-1 can send the context 215 of the terminal device 210 to the core network device 102. Correspondingly, the core network device 102 can receive the context 215 of the terminal device 220 from the first network device 110-1. For example... Figure 3 As described above, Sat1 can cache the terminal device's data until time T13 when it moves to the gateway station for backhaul, and the terminal device's context is also backhauled to the core network. In some examples, after sending the terminal device's context 215 to the core network device 102, the first network device 110-1 can delete the local terminal device's context 215. It should be understood that sending the terminal device's context 215 to the core network device 102 by the first network device 110-1 is optional. In one example, the core network device 102 can store the context of the terminal device 120. The core network device 102 can push the context of the terminal device 120 to network devices passing through the terminal device 120. When the core network device 102 receives a NAS instruction from the terminal device 120 or an NGAP (NG Application Protocol) instruction from the network device, it stops pushing the context. The NGAP instruction instructs the core network device 102 to delete the context of the terminal device 120. In another example, core network device 102 stores the context of terminal devices. First network device 110-1 can send a context indication of terminal device 120 back to core network device 102, such as an ID associated with terminal device 120 or an ID associated with the context of terminal device 120. When core network device 102 receives the context indication of terminal device 120, it can determine whether the context of terminal device 120 needs to be pushed to other network devices (such as second network device 110-2).

[0097] Continue to refer to Figure 2First network device 110-1 sends connection release message 230 (225) to terminal device 120. Connection release message 230 includes identification information of terminal device 120 assigned by first network device 110-1. The identification information may be a group identifier associated with the terminal device, which may be associated with multiple terminal devices. It should be understood that first network device 110-1 may also inform terminal device 120 of the identification information of terminal device 120 assigned by first network device 110-1 via other messages. Alternatively or additionally, connection release message 230 may also include a first indication, which instructs terminal device 120 to add identification information. Correspondingly, terminal device 120 receives connection release message 235 (235) from first network device 110-1, which includes the identification information of terminal device 120 assigned by first network device 110-1. In some embodiments, terminal device 120 may also receive the identification information of terminal device 120 assigned by first network device 110-1 via other messages. In one example, when the first network device 110-1 releases the terminal device 120, it assigns the terminal device 120 an identifier associated with the terminal device 120 context, such as an Inactive Radio Network Temporary Identifier (I-RNTI), or a group identifier associated with the terminal device 120 to save broadcast signaling overhead.

[0098] It should be understood that the order in which the first network device 110-1 sends the terminal device's context to the core network device and sends the connection release message to the terminal device in process 200 is merely illustrative and not restrictive. In some embodiments, the first network device 110-1 may send the connection release message to the terminal device first and then send the terminal device's context to the core network device, or send both messages simultaneously.

[0099] Terminal device 120 can perform uplink or downlink data transmission with multiple network devices. In some embodiments, when terminal device 120 performs downlink data transmission with multiple network devices, core network device 102 can copy the data multiple times and distribute it to terminal device 120 through multiple network devices. In one example, each network device stores a complete data file, and during transmission, it starts sending from the first data packet of the file stored in the network device. In another example, each network device stores a partial data file, and during transmission, it starts sending from the first data packet of the file stored in the network device, with duplicate packet detection and deletion performed at the terminal device. Figure 4 A schematic diagram of multiple satellite storage files according to some embodiments of the present disclosure is shown. As shown, SAT1, SAT2, and SAT3 each store a portion of the complete data, and the content stored by each satellite may be repeated to ensure data continuity.

[0100] In some embodiments, before receiving the connection release message 230, the terminal device 120 receives data packets from the first network device 110-1, meaning that the terminal device 120 and the first network device 110-1 have performed downlink data transmission. The connection release message 230 may further include: first sequence number information or a third indication. The first sequence number information indicates the sequence number of a successfully transmitted data packet, and the third indication instructs the terminal device 120 to send second sequence number information to the second network device 110-2. The second sequence number information includes the first sequence number information or the sequence number of a successfully transmitted data packet determined by the terminal device 120. It should be understood that the data packet indicated by the first or second sequence number information can be a successfully transmitted or received data packet, or the next data packet after a successfully received data packet, i.e., the first data packet expected to be received. For example, the first sequence number information can be the data number corresponding to a data packet for which the base station has received an acknowledgment character (ACK), indicating a successfully transmitted downlink data packet. In other words, when the first network device 110-1 releases the terminal device 120, it also assigns a data reference number (i.e., the sequence number of the successfully transmitted data packet) to the terminal device, or instructs the terminal device to determine the data reference number itself and report the reference number to the second network device 110-2 in the future.

[0101] Continue to refer to Figure 2 Core network device 102 sends 240, the identification information of terminal device 120 allocated by first network device 110-1, and context 245 of terminal device 120 to second network device 110-2. Second network device 110-2 will serve terminal device 120 in a second time period following the first time period. Correspondingly, second network device 110-2 receives 250, the identification information of terminal device 120 allocated by first network device 110-1, and context 245 of terminal device 120 from core network device 102. For example, AMF can push the terminal device context to Sat2 (i.e., second network device 110-2) at time T23.

[0102] In some embodiments, before sending the context of terminal device 120, core network device 102 receives from first network device 110-1 the identification information of terminal device 120 and the identifier of the context of terminal device 120, which are allocated by first network device 110-1. The identifier of the context of terminal device 120 may include: a group identifier of a plurality of terminal devices including terminal device 120, a context identifier of terminal device 120, the context of terminal device 120, or one or more of the above.

[0103] Continue to refer to Figure 2The second network device 110-2 sends broadcast information 260, which includes identification information of the terminal device 120 assigned by the first network device 110-1. The terminal device 120 receives broadcast information 260 from the second network device 110-2. For example, the second network device 110-2 broadcasts the currently cached context identifier or group identifier of the terminal device. The broadcast information can be the terminal device's I-RNTI, context identifier, group identifier, or a group identifier associated with the terminal device's context. Correspondingly, the terminal device reads the broadcast information when it enters the coverage area of ​​the second network device 110-2, for example, T21.

[0104] Based on the identification information and broadcast information 260, terminal device 120 determines 270 to access the second network device 110-2. For example, terminal device 120 can determine whether the broadcast information matches the identification information. If the broadcast information matches the identification information, it can determine that the second network device has the context of terminal device 120. In one example, if the broadcast information contains the context identifier of terminal device 120 or a group identifier associated with terminal device 120, terminal device 120 can determine whether the broadcast information matches the identification information, and thus determine to access the second network device.

[0105] In some embodiments, the identification information further includes a list of device identifiers for at least one network device having the context of terminal device 120. Broadcast information 260 includes the device identifier of the second network device 110-2. If it is determined that the list of device identifiers includes the device identifier of the second network device 110-2, terminal device 120 can access the second network device 110-2. In one example, the RRC release message may carry at least one satellite ID to identify which satellites have UE context.

[0106] Additionally, the connection release message may also include timer information, prohibiting terminal device 120 from accessing the network device (e.g., a second network device) during the timer's execution. Prohibiting access to the network device may only mean prohibiting terminal device 120 from accessing the network device using RRC Resume. In some additional scenarios, such as emergency communication, terminal device 120 may access the network device via RRC Setup. For example, the RRC release message may also carry a timer to prohibit terminal device 120 from accessing the network device during the timer's execution (e.g., ...). Figure 3Before T23, the device reconnects to other satellites, allowing the context time to switch to the target satellite Sat2. Although Sat2 covers the area where terminal device 120 is located, terminal device 120 cannot access Sat2 because Sat2 does not have the context of terminal device 120 at this time, and terminal device 120 cannot quickly access Sat2 through RRC recovery.

[0107] In some embodiments, terminal device 120 can access the second network device 110-2 via a connection recovery message. For example, terminal device 120 can access the second network device 110-2 through the RRC Connection Resume procedure without needing to re-establish the UE context (i.e., the RRC Connection Setup procedure) and continue data transmission.

[0108] In one example, if terminal device 120 is transmitting downlink data with a network device, terminal device 120 can send a second sequence number to the second network device 110-2. Correspondingly, the second network device 110-2 can receive the sequence number of a data packet successfully transmitted by the first network device 110-1 from terminal device 120. Additionally, the sequence number (SN) of the data packet successfully transmitted by the first network device (i.e., the second sequence number information) can be carried via a connection recovery message. For example, when terminal device 120 accesses Sat2 via the RRC Connection Resume procedure, it provides a data reference number (e.g., a PDCP status report) to enable the second network device 110-2 to continue downlink data transmission, avoiding duplicate data transmission.

[0109] In another example, before receiving the connection release message 230, the first network device 110-1 sends a data packet to the terminal device 120, meaning that the terminal device 120 and the first network device 110-1 perform downlink data transmission. The first network device 110-1 can also send a first sequence number to the core network device 102, indicating a successfully transmitted data packet. The core network device 102 can receive the first sequence number from the first network device 110-1 and send it to the second network device 110-2. The second network device 110-2 can receive the sequence number of the data packet successfully transmitted by the first network device 110-1 from the core network device 102. In other words, the first network device 110-1 informs the second network device 110-2 of the data reference number (i.e., the successfully transmitted data packet). In this way, the terminal device does not need to receive the data reference number from the first network device and provide it to the second network device, allowing the second network device to directly know from which data reference number to start transmitting data. Accordingly, the alignment of data reference numbers between the first and second network devices can be accomplished by the first network device sending its data reference number (e.g., PDCP SN) to the AMF via an uplink RAN ​​STATUS TRANSFER message. The AMF then sends the PDCP SN to the second network device via a downlink RAN ​​STATUS TRANSFER message.

[0110] Furthermore, if terminal device 120 performs downlink data transmission with first network device 110-1, first network device 110-1 can send a number associated with the data packet transmission status to core network device 102 to ensure data transmission continuity. In one example, when network device 120 and terminal device 120 are performing downlink transmission, core network device 102 receives data packets from first network device 110-1 that were not successfully transmitted by first network device 110-1. It then sends these data packets to second network device 110-2. For example, Sat1 can send data for which no feedback has been received and the transmission success cannot be confirmed back to the UPF. The UPF then forwards this data to Sat2, and only after this data is sent does it send the data received from the core network.

[0111] In another example, core network device 102 receives a number associated with the packet transmission status from first network device 110-1. Based on the number, core network device 102 downloads packets that were not successfully transmitted by the first network device and sends these packets to second network device 110-2. For example, Sat1 informs the UPF of the number (e.g., QoS Flow ID SN, QFI SN) corresponding to data for which no feedback was received and transmission success cannot be confirmed, requesting the UPF to cache this data. The QFI (Quality of Service Flow ID) SN corresponds to the aforementioned data reference number. Combining the received QFI SN, the UPF forwards the data not transmitted to the UE and the data received from the core network to Sat2.

[0112] Additionally, based on the sequence number of the data packets successfully transmitted by the first network device 110-1, the second network device 110-2 performs data transmission with the terminal device 120. In some embodiments, if the second network device 110-2 performs downlink data transmission with the terminal device 120, the second network device 110-2 may also receive first data from the core network device 102, the first data being data that the first network device 110-1 failed to transmit. The second network device 110-2 then sends the first data to the terminal device 120, and then sends the second data received from the core network device 102 to the terminal device 120. For example, the second data may be as follows: Figure 4 The image shows a portion of the complete data stored in SAT2.

[0113] Furthermore, if data transmission between the second network device 110-2 and the terminal device 120 is completed, the second network device 110-2 sends a fourth instruction to the core network device 102. The fourth instruction instructs the core network device 102 to notify at least one network device possessing the context of the terminal device 120 to delete at least one of the context or identification information of the terminal device 120. The second network device 110-2 may also send a connection release message to the terminal device, the connection release message including the second instruction. The second instruction instructs the terminal device 120 to delete the identification information. Correspondingly, the core network device 102 receives the fourth instruction from the second network device 110-2. The core network device 102 then sends a fifth instruction to at least one network device, the fifth instruction instructing the at least one network device to delete the first identification. Correspondingly, the connection release message 230 received by the terminal device 120 from the first network device is a first connection release message, and the terminal device 120 may also receive a second connection release message from the second network device 110-2. The second connection release message may include the second instruction.

[0114] In one example, assuming data transmission between terminal device 120 and the network device is complete, Sat2 notifies the terminal device to delete its context or group identifier via an RRC release message and informs the AMF, causing the AMF to notify subsequent satellites (e.g., Sat3, Sat4) to remove the context of terminal device 120. Sat3 and Sat4 can then remove the context of terminal device 120 from the group without changing the group identifier, minimizing the impact on other terminal devices. In another example, if Sat3 has not yet received notification from the AMF when it overwrites terminal device 120, Sat3 retains and broadcasts the context of terminal device 120. However, because the terminal device has no uplink data, or because of the RRC release message, it is notified that it does not need to access Sat3.

[0115] In another example, assuming Sat2 caches the complete downlink data, when the downlink data transmission with terminal device 120 is complete, Sat2 deletes the context, group identifier, or I-RNTI of terminal device 120 via an RRC release message. Simultaneously, Sat2 informs the AMF that the data transmission of terminal device 120 has ended, allowing the AMF to notify subsequent Sat3 and Sat4 to cancel the UE's context without sending a paging message to the UE. Sat3 and Sat4 can directly remove the context of terminal device 120 from the group without renaming the group identifier. In another example, if Sat3 has not yet received notification when it overwrites terminal device 120, Sat3 still retains and broadcasts the UE context. However, because terminal device 120 knows that Sat3 has no downlink data (data endMarker) or has already deleted the I-RNTI, it will not respond to paging.

[0116] In this way, the context of the terminal device is pushed forward to the subsequent set of network devices in advance. The subsequent network devices broadcast the available terminal device context, enabling the terminal device to connect to new network devices more quickly. At the end of data transmission, the state information (context update, etc.) at both ends of the terminal device and the set of network devices is aligned, thereby reducing unnecessary overhead.

[0117] To gain a more thorough and complete understanding of this disclosure, reference will be made to... Figure 5 and Figure 6 This section discusses two specific implementation methods for the terminal device access process. It should be noted that... Figure 5 and Figure 6 Each part of this document may be used individually or in any combination, and is for illustrative purposes only and is not intended to limit the scope of protection of this disclosure.

[0118] Figure 5 The illustration shows a first example process 500 according to some embodiments of the present disclosure, which can be considered as Figure 2This is a specific implementation of process 200. For the sake of clarity and without any limitation, process 500 will be combined with... Figure 3 Let's discuss this further.

[0119] In step 511, UE 120 performs uplink data transmission with SAT1(RAN1)110-1. SAT1(RAN1)110-1 in... Figure 3 During T11 to T12, UE 120 is covered. At 513, SAT1(RAN1)110-1 caches the data of UE 120. At 515, SAT1(RAN1)110-1 accesses the gateway station at time T13 to send a backhaul to CN 102, at least one of the UE 120 context and the group identifier associated with UE 120. At 517, SAT1(RAN1)110-1 sends an RRRCRelease message to UE 120, assigning UE 120 an identifier associated with the UE 120 context, such as I-RNTI, or the group identifier associated with UE 120.

[0120] At 519, CN 102 sends the context of UE 120 and the group identifier associated with UE 120 to SAT2(RAN2)110-2 at T23. During T21 to T22, SAT2(RAN2)110-2 can cover UE 120. At 521, SAT2(RAN2)110-2 broadcasts system information. The system information may include identifiers associated with the UE 120 context, such as the group identifier.

[0121] At 523, UE 120 decides to access SAT2(RAN2)110-2. At 525, UE 120 accesses SAT2(RAN2)110-2 via the RRCConnectionResume procedure to continue uplink data transmission. At 527, Figure 3 During the T23+SAT2 cycle shown, which is after UE 120 completes its uplink transmission and SAT2(RAN2)110-2 no longer covers UE 120, SAT2(RAN2)110-2 notifies the AMF to update the context or group identifier. The AMF then notifies subsequent satellites to cancel the UE's context, eliminating the need to send paging messages to the UE. At 529, SAT2(RAN2)110-2 notifies the UE to delete the context or group identifier via the RRRCRelease message.

[0122] In this way, the network assists UE 120 in determining whether it can access the satellite by broadcasting indication information. UE 120 can quickly re-establish a connection with the new satellite using the RRC recovery method, rather than re-establishing the context through initial access such as RRCSetup.

[0123] Figure 6 The illustration shows a first example process 600 according to some embodiments of the present disclosure, which can be considered as Figure 2 This is a specific implementation of process 200. For the sake of clarity and without any limitation, process 60 will be combined with... Figure 3 Let's discuss this further.

[0124] In step 611, UE 120 performs downlink data transmission with SAT1(RAN1)110-1. SAT1(RAN1)110-1 in... Figure 3 The diagram shows that UE 120 is covered during T11 to T12, assuming data transmission continues until time T12, which is the end time of SAT1(RAN1)110-1's service. At 613, SAT1(RAN1)110-1 buffers the UE 120 context. At 615, upon accessing the gateway station at time T13, SAT1(RAN1)110-1 forwards the UE 120 context to CN 102, indicating that the data reference number of the data packets successfully transmitted by SAT1(RAN1)110-1 can also be forwarded to CN 102. At 617, SAT1(RAN1)110-1 sends an RRRCRelease message to UE 120, assigning UE 120 a UE 120 context-associated identifier, such as I-RNTI, or a group identifier associated with UE 120. If the data reference number is not sent to CN 102 in 615, the data reference number can be sent to UE 120 in 617 and will be sent to SAT2(RAN2)110-2 in 625.

[0125] At 619, CN 102 sends the context of UE 120 and the group identifier associated with UE 120 to SAT2(RAN2)110-2 at T23. SAT2(RAN2)110-2 can cover UE 120 during T21 to T22. If a data reference number is sent to CN 102 in 615, the data reference number can be sent to SAT2(RAN2)110-2 in 619.

[0126] In 621, SAT2(RAN2)110-2 broadcasts the UE context currently cached by the satellite. Correspondingly, when UE 120 enters the satellite coverage area, such as T21, it reads the broadcast information. The broadcast information may be the UE's I-RNTI, context identifier, group identifier associated with UE 120, or group identifier associated with the context of UE 120.

[0127] At 623, UE 120 decides to access SAT2(RAN2)110-2. At 625, UE 120 accesses SAT2(RAN2)110-2 through the RRCConnectionResume procedure to continue uplink data transmission. If UE 120 received a data reference number in 617, or received an indication to report a reference number, UE 120 will also send a data reference number to SAT2(RAN2)110-2 during the RRCConnectionResume procedure. The data reference number can be received from SAT1(RAN1)110-1, or it can be determined by UE 120 itself.

[0128] At 627, at Figure 3 The T23+SAT2 cycle shown refers to the period after the network and UE 120 complete downlink transmission. For example, after SAT2(RAN2)110-2 has buffered the complete DL data and the downlink transmission with UE 120 is finished, SAT2(RAN2)110-2 notifies the AMF to update the context or group identifier. In step 629, SAT2(RAN2)110-2 notifies the UE to delete the context or group identifier via the RRRCRelease message.

[0129] In this way, data reference numbers are synchronized among satellites to reduce unnecessary duplicate transmissions. Downlink data transmission progress is aligned, thus synchronizing data transmission progress among multiple satellites.

[0130] Figure 7 A schematic flowchart of a method 700 implemented at a terminal device according to an embodiment of the present disclosure is illustrated. For clarity and without limitation, process 700 will be described in conjunction with... Figure 1A The following discussion will focus on this. In one possible implementation, method 700 can be implemented by terminal device 120 in communication system 100. In other possible implementations, method 700 can also be implemented by other communication devices independent of communication system 100. As an example, method 700 will be described below using implementation by terminal device 120 in communication system 100 as an example.

[0131] In block 710, terminal device 120 receives a connection release message from a first network device, the connection release message including identification information of the terminal device assigned by the first network device. In block 720, terminal device 120 receives broadcast information from a second network device, the broadcast information including identification information of the terminal device assigned by the first network device. In block 730, terminal device 120 determines whether to access the second network device based on the identification information and the broadcast information. Method 700 may also include various operations or functions described in the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0132] Figure 8 A schematic flowchart of a method 800 implemented at a first network device according to an embodiment of the present disclosure is illustrated. For clarity and without limitation, process 800 will be described in conjunction with... Figure 1A The following discussion will focus on this. In one possible implementation, method 800 can be implemented by the first network device 110-1 in communication system 100. In other possible implementations, method 800 can also be implemented by other communication devices independent of communication system 100. As an example, method 800 will be described below using implementation by the first network device 110-1 in communication system 100 as an example.

[0133] In block 810, the first network device 110-1 decides to release the terminal device to an inactive state. In block 820, the first network device 110-1 sends the context of the terminal device to the core network device. In block 830, the first network device 110-1 sends a connection release message to the terminal device, the connection release message including the identification information of the terminal device assigned by the first network device. Method 800 may also include various operations or functions described in the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0134] Figure 9 A schematic flowchart illustrating a method 900 implemented at a second network device according to an embodiment of the present disclosure is shown. For clarity and without limitation, process 900 will be described in conjunction with... Figure 1A The following discussion will focus on this. In one possible implementation, method 900 can be implemented by the second network device 110-2 in communication system 100. In other possible implementations, method 900 can also be implemented by other communication devices independent of communication system 100. As an example, method 900 will be described below using implementation by the second network device 110-2 in communication system 100 as an example.

[0135] In block 910, the second network device 110-2 receives the terminal device identification information and the terminal device context assigned by the first network device from the core network device. In block 920, the second network device 110-2 sends broadcast information, which includes the terminal device identification information assigned by the first network device. Method 900 may also include various operations or functions described in the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0136] Figure 10 A schematic flowchart illustrating a method 1000 implemented at a core network device according to an embodiment of the present disclosure is shown. For clarity and without limitation, process 1000 will be described in conjunction with... Figure 1A The following discussion will focus on this. In one possible implementation, method 1000 can be implemented by the core network device 102 in the communication system 100. In other possible implementations, method 1000 can also be implemented by other communication devices independent of the communication system 100. As an example, method 1000 will be described below using implementation by the core network device 102 in the communication system 100 as an example.

[0137] In block 1010, core network device 102 sends the terminal device's identification information and context, allocated by the first network device, to the second network device, wherein the second network device will serve the terminal device in a second time period following the first time period. Method 1000 may also include various operations or functions described in the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0138] Figure 11 This is a block diagram of the device 1100 that can be used to implement some embodiments of the present application. In some embodiments, the device 1100 may be an element of a communication network infrastructure, such as a base station (e.g., NodeB, evolved NodeB (eNodeB or eNB), next-generation NodeB (sometimes referred to as gNodeB or gNB), Home Subscriber Server (HSS), gateway (GW), such as a packet gateway (PGW) or serving gateway (SGW), or various other nodes or functions within a core network (CN) or public land mobile network (PLMN). In other embodiments, the device 1100 may be a device connected to the network infrastructure via a wireless interface, such as a mobile phone, smartphone, or other such device that can be classified as user equipment (UE). In some embodiments, the device 1100 may be a machine-type communication (MT) device. C) Device (also known as machine-to-machine (M2M) device), or another such device that can be classified as a UE even though it does not provide direct service to a user. In some embodiments, device 1100 may be a roadside unit (RSU), vehicle UE (V-UE), pedestrian UE (P-UE), or infrastructure UE (I-UE). In some scenarios, device 1100 may also be referred to as a mobile device, a term intended to reflect a device connected to a mobile network, regardless of whether the device itself is designed for or capable of being mobile. A particular device may utilize all or only a subset of the components shown, and the level of integration may vary depending on the device. Furthermore, device 1100 may contain multiple instances of components, such as multiple processors, memory, transmitters, receivers, etc.

[0139] Device 1100 typically includes a processor 1102, such as a central processing unit (CPU), and may further include a dedicated processor, such as a graphics processing unit (GPU) or other such processor, memory 1104, a network interface 1106, and a bus 1108 for connecting the components of device 1100. Optionally, device 1100 may also include components such as a mass storage device 1110, a video adapter 1112, and an I / O interface 1116 (shown in dashed lines).

[0140] Memory 1104 may include any type of non-transitory system memory readable by processor 1102, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or combinations thereof. In one embodiment, memory 1104 may include more than one type of memory, such as ROM used at startup and DRAM used for program and data storage during program execution. Bus 1108 may be one or more of a plurality of bus architectures of any type, including a memory bus or memory controller, a peripheral bus, or a video bus.

[0141] Device 1100 may also include one or more network interfaces 1106, which may include at least one of wired network interfaces and wireless network interfaces. For example... Figure 11 As shown, network interface 1106 may include a wired network interface for connecting to network 1122, and may also include a wireless access network interface 1120 for connecting to other devices via a wireless link. When device 1100 is a network infrastructure element, the wireless access network interface 1120 may be omitted for nodes or functions that are elements of a PLMN rather than elements at the wireless edge (e.g., eNB). When device 1100 is infrastructure at the wireless edge of the network, both wired and wireless network interfaces may be included. When device 1100 is a wirelessly connected device, such as a user equipment, the wireless access network interface 1120 may be present and may be supplemented by other wireless interfaces such as a WiFi network interface. Network interface 1106 allows device 1100 to communicate with remote entities such as those connected to network 1122.

[0142] Mass storage 1110 may include any type of non-transitory storage device configured to store data, programs, and other information and make the data, programs, and other information accessible via bus 1108. Mass storage 1110 may include, for example, one or more of a solid-state drive, hard disk drive, disk drive, or optical disk drive. In some embodiments, mass storage 1110 may be located remotely from device 1100 and may be accessed using a network interface such as interface 1106. In the illustrated embodiment, mass storage 1110 is distinct from the memory 1104 that includes it, and mass storage 1110 typically performs storage tasks compatible with higher latency but typically provides low or no fluctuation. In some embodiments, mass storage 1110 may be integrated with heterogeneous memory 1104.

[0143] Optional video adapter 1112 and I / O interface 1116 (shown in dashed lines) provide interfaces for coupling device 1100 to external input and output devices. Examples of input and output devices include a display 66 coupled to video adapter 1112 and an I / O device 1118, such as a touchscreen, coupled to I / O interface 1116. Other devices may be coupled to device 1100 and may utilize additional or fewer interfaces. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide interfaces for external devices. Those skilled in the art will understand that in embodiments where device 1100 is part of a data center, I / O interface 1116 and video adapter 1112 may be virtualized and provided via network interface 1106.

[0144] Figure 12 This is a schematic diagram of the structure of a device 1200 according to some embodiments of this application. For example... Figure 12As shown, device 1200 includes a first receiving unit 1202, a second receiving unit 1204, and a determining unit 1206. Device 1200 can be applied to the communication system shown in FIG. 1 and can implement any of the methods provided in the embodiments above. Optionally, the physical manifestation of device 1200 can be a communication device, such as a network device or UE. Alternatively, device 1200 can be other devices capable of implementing the functions of a communication device, such as a processor or chip inside the communication device. Specifically, device 1200 can be a programmable chip, such as a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), an application-specific integrated circuit (ASIC), or a system on a chip (SOC).

[0145] In some embodiments, the first receiving unit 1202 may be configured to receive a connection release message from a first network device, the connection release message including identification information of a terminal device assigned by the first network device. The second receiving unit 1204 may be configured to receive broadcast information from a second network device, the broadcast information including identification information of a terminal device assigned by the first network device. The determining unit 1206 may be configured to determine access to the second network device based on the identification information and the broadcast information.

[0146] In some other embodiments, the apparatus 1200 may include various other units or modules that can be configured to perform the various operations or functions described with respect to the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0147] Figure 13 This is a schematic diagram of the structure of device 1300 according to some embodiments of this application. For example... Figure 13As shown, device 1300 includes a decision unit 1302, a first transmission unit 1304, and a second transmission unit 1306. Device 1300 can be applied to the communication system shown in FIG. 1 and can implement any of the methods provided in the embodiments above. Optionally, the physical manifestation of device 1300 can be a communication device, such as a network device or UE. Alternatively, device 1300 can be other devices capable of implementing the functions of a communication device, such as a processor or chip inside a communication device. Specifically, device 1300 can be a programmable chip, such as a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), an application-specific integrated circuit (ASIC), or a system on a chip (SOC).

[0148] In some embodiments, the decision unit 1302 may be configured to decide to release the terminal device to an inactive state. The first sending unit 1304 may be configured to send the context of the terminal device to the core network device. The second sending unit 1306 may be configured to send a connection release message to the terminal device, the connection release message including the identification information of the terminal device assigned by the first network device.

[0149] In some other embodiments, the apparatus 1300 may include various other units or modules that can be configured to perform the various operations or functions described with respect to the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0150] Figure 14 This is a schematic diagram of the structure of a device 1400 according to some embodiments of this application. For example... Figure 14As shown, device 1400 includes a receiving unit 1402 and a transmitting unit 1404. Device 1400 can be applied to the communication system shown in FIG. 1 and can implement any of the methods provided in the embodiments above. Optionally, the physical manifestation of device 1400 can be a communication device, such as a network device or UE. Alternatively, device 1400 can be other devices capable of implementing the functions of a communication device, such as a processor or chip inside the communication device. Specifically, device 1400 can be a programmable chip, such as a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), an application-specific integrated circuit (ASIC), or a system on a chip (SOC).

[0151] In some embodiments, the receiving unit 1402 may be configured to receive, from the core network device, the identification information of the terminal device and the context of the terminal device assigned by the first network device. The sending unit 1404 may be configured to send broadcast information, the broadcast information including the identification information of the terminal device assigned by the first network device.

[0152] In some other embodiments, the apparatus 1400 may include various other units or modules that can be configured to perform the various operations or functions described with respect to the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0153] Figure 15 This is a schematic diagram of the structure of a device 1500 according to some embodiments of this application. For example... Figure 15As shown, device 1500 includes a transmitting unit 1502. Device 1500 can be applied to the communication system shown in FIG. 1 and can implement any of the methods provided in the embodiments above. Optionally, the physical manifestation of device 1500 can be a communication device, such as a network device or UE. Alternatively, device 1500 can be other devices capable of implementing the functions of a communication device, such as a processor or chip inside a communication device. Specifically, device 1500 can be a programmable chip, such as a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), an application-specific integrated circuit (ASIC), or a system on a chip (SOC).

[0154] In some embodiments, the sending unit 1502 may be configured to send the identification information of the terminal device allocated by the first network device and the context of the terminal device to the second network device, and the second network device will serve the terminal device in a second time period after the first time period.

[0155] In some other embodiments, the apparatus 1500 may include various other units or modules that can be configured to perform the various operations or functions described with respect to the foregoing method embodiments. Specific details can be obtained by referring to the detailed description of the foregoing method embodiments, and will not be repeated here.

[0156] It should be noted that the module division in the above embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, exist as separate physical units, or be integrated into one unit by two or more units. The integrated units described above can be implemented in hardware or as software functional units.

[0157] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, or all or part of it, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0158] Based on the above embodiments, this application also provides a computer program that, when run on a computer, causes the computer to execute any of the methods provided in the above embodiments.

[0159] Based on the above embodiments, this application also provides a computer-readable storage medium storing a computer program. When executed by a computer, the computer program causes the computer to perform any of the methods provided in the above embodiments. The storage medium can be any available medium that can be accessed by a computer. By way of example, but not limited to, a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code having the form of instructions or data structures and that can be accessed by a computer.

[0160] Based on the above embodiments, this application also provides a chip for reading a computer program stored in a memory and implementing any of the methods provided in the above embodiments.

[0161] Based on the above embodiments, this application provides a chip system including a processor for supporting a computer device in implementing the functions involved in the communication devices in the above embodiments. In one possible design, the chip system further includes a memory for storing necessary programs and data of the computer device. This chip system may be composed of chips or may include chips and other discrete components.

[0162] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0163] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0164] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0165] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0166] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A communication method, comprising: Receive a connection release message from the first network device, the connection release message including the identification information of the terminal device assigned by the first network device; Receive broadcast information from the second network device, the broadcast information including the identification information of the terminal device assigned by the first network device; as well as Based on the identification information and the broadcast information, access to the second network device is determined.

2. The method according to claim 1, wherein the identification information further includes a list of device identifiers of at least one network device having the context of the terminal device, the broadcast information includes the device identifier of the second network device, and determining access to the second network device includes: The device identifier list is determined to include the device identifier of the second network device.

3. The method according to claim 1 or 2, wherein the connection release message further comprises: Information about a timer, wherein the terminal device is prohibited from accessing network devices during the operation of the timer.

4. The method according to any one of claims 1 to 3, wherein the connection release message further includes a first indication, the first indication being used to instruct the terminal device to add the identification information.

5. The method according to any one of claims 1 to 4, wherein the connection release message received from the first network device is a first connection release message, the method further comprising: The terminal device receives a second connection release message from the second network device. The second connection release message includes a second indication, which instructs the terminal device to delete at least one of the terminal device's context or its identification information.

6. The method according to any one of claims 1 to 5, wherein before receiving the connection release message, the terminal device receives a data packet from the first network device, and the connection release message further comprises at least one of the following: First sequence number information, indicating the sequence number of a data packet that has been successfully transmitted; or The third instruction is used to instruct the terminal device to send second sequence number information to the second network device, wherein the second sequence number information includes at least one of the following: first sequence number information or the sequence number of a data packet that has been successfully transmitted and determined by the terminal device.

7. The method according to claim 6, further comprising: Access to the second network device is achieved via a connection restoration message.

8. The method according to claim 7, further comprising: Send the second serial number information to the second network device.

9. A communication method, comprising: The decision was made to release the terminal device into an inactive state; Send the context of the terminal device to the core network equipment; A connection release message is sent to the terminal device, the connection release message including the identification information of the terminal device assigned by the first network device.

10. The method of claim 9, wherein before releasing the terminal device, the first network device sends a data packet to the terminal device, and the connection release message further includes at least one of the following: First sequence number information, indicating the sequence number of a data packet that has been successfully transmitted; or The third instruction is used to instruct the terminal device to send second sequence number information to the second network device, wherein the second sequence number information includes at least one of the following: first sequence number information or the sequence number of a data packet that has been successfully transmitted and determined by the terminal device.

11. The method of claim 9, wherein before releasing the terminal device, the first network device sends a data packet to the terminal device, the method further comprising: Send a first sequence number to the core network device. The sequence number of the first data packet indicates a data packet that has been successfully transmitted.

12. The method according to any one of claims 9 to 11, wherein before releasing the terminal device, the first network device sends a data packet to the terminal device, the method further comprising: Send a number associated with the data packet transmission status to the core network equipment.

13. A communication method, comprising: Receive from the core network equipment the identification information of the terminal device assigned by the first network device and the context of the terminal device; as well as Send a broadcast message, the broadcast message including the identification information of the terminal device assigned by the first network device.

14. The method of claim 13, further comprising: Based on the determination that data transmission between the second network device and the terminal device is completed, a fourth instruction is sent to the core network device. The fourth instruction is used to instruct the core network device to notify at least one network device that has the context of the terminal device to delete at least one of the context or the identification information of the terminal device. as well as A connection release message is sent to the terminal device, the connection release message including a second indication, the second indication being used to instruct the terminal device to delete the identification information.

15. The method of claim 14, wherein the second network device and the terminal device perform downlink transmission, further comprising at least one of the following: The terminal device receives the sequence number of a data packet that has been successfully transmitted by the first network device, the sequence number of which is carried in a connection recovery message; or Receive the sequence number of the data packet that has been successfully transmitted by the first network device from the core network device.

16. The method of claim 15, further comprising: Data transmission is performed based on the sequence number of the data packet that has been successfully transmitted by the first network device.

17. The method of claim 14, wherein the second network device and the terminal device perform downlink transmission, further comprising: Receive first data from the core network device, wherein the first data is data that the first network device failed to transmit; Send the first data to the terminal device; as well as Send the second data received from the core network device to the terminal device.

18. A communication method, comprising: The second network device sends the terminal device's identification information and context, which were assigned by the first network device, to the second network device, wherein the second network device will serve the terminal device in a second time period following the first time period.

19. The method of claim 18, further comprising: Before sending the context of the terminal device, the identification information of the terminal device and the identifier of the context of the terminal device, which are assigned by the first network device, are received from the first network device.

20. The method of claim 18, wherein the second network device and the terminal device perform downlink transmission, further comprising: The first sequence number information of the data packet is received from the first network device, wherein the sequence number information of the first data packet indicates that the data packet has been successfully transmitted by the first network device; as well as The sequence number information of the first data packet is sent to the second network device.

21. The method of claim 18, wherein the second network device and the terminal device perform downlink transmission, further comprising: Receive data packets that were not successfully transmitted by the first network device; as well as Send the data packets that were not successfully transmitted by the first network device to the second network device.

22. The method of claim 18, wherein the second network device and the terminal device perform downlink transmission, further comprising: Receive a number associated with the packet transmission status from the first network device; Download the data packets that were not successfully transmitted by the first network device based on the number; as well as Send the data packets that were not successfully transmitted by the first network device to the second network device.

23. The method according to any one of claims 18 to 22, further comprising: The core network device receives a fourth instruction from the second network device, the fourth instruction being used to instruct the core network device to notify at least one network device having the context of the terminal device to delete at least one of the context or the identification information of the terminal device; as well as A fifth instruction is sent to the at least one network device, the fifth instruction being used to instruct the at least one network device to delete the first identifier.

24. A communication device, comprising: A processor and a memory storing instructions, which, when executed by the processor, cause the communication device to perform the method according to any one of claims 1 to 8, any one of claims 9 to 12, any one of claims 13 to 17, or any one of claims 18 to 23.

25. A chip comprising processing circuitry configured to perform the method according to any one of claims 1 to 8, any one of claims 9 to 12, any one of claims 13 to 17, or any one of claims 18 to 23.

26. A computer-readable storage medium storing instructions that, when executed by a communication device, cause the communication device to perform the method according to any one of claims 1 to 8, any one of claims 9 to 12, any one of claims 13 to 17, or any one of claims 18 to 23.

27. A computer program product comprising computer-executable instructions, which, when executed, cause the communication device to perform the method according to any one of claims 1 to 8, any one of claims 9 to 12, any one of claims 13 to 17, or any one of claims 18 to 23.

Images