A communication method and apparatus

Abstract

The application provides a communication method and device, in which a terminal device sends context information stored by the terminal device to a network device (an access network device and / or a core network element). In this way, the network device before handover does not need to send the context information of the terminal device to the network device after handover, and the signaling overhead between the network devices can be saved; or the access network device and the core network element do not need to perform signaling interaction to create the context of the terminal device, and the signaling overhead between the access network device and the core network element can be saved.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411774296.2, filed on December 4, 2024, entitled "A Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0004] In non-terrestrial networks, satellites serving terminal devices frequently switch over. When network equipment (access network equipment and / or core network elements) is deployed on satellites, the network equipment serving the terminal devices also switches over frequently. Due to the frequent switching of network equipment, the signaling overhead on the network side is extremely high. Summary of the Invention

[0005] This application provides a communication method and apparatus for reducing signaling overhead on the network side.

[0006] Firstly, this method can be applied to the network side, such as network devices, modules (e.g., circuits, chips, or chip systems) within network devices, or logical nodes, logical modules, or software capable of implementing all or part of the functions of the network devices. For example, network devices include access network devices and / or core network elements. Taking the application of this method to a network device as an example, in this method, the terminal device is in a first state, which is a deactivated state, an idle state, or a connected state; the network device receives context information stored by the terminal device from the terminal device; based on the context information, the network device sends a first message to the terminal device, the first message indicating that the terminal device transitions from the first state to a second state; the second state is a deactivated state, an idle state, or a connected state; the first state and the second state are different.

[0007] In this method, the terminal device sends its stored context information to the network device, eliminating the need for the network device before handover to send the terminal device's context information to the network device after handover, thus saving signaling overhead between network devices. Alternatively, it eliminates the need for signaling interaction between the access network device and core network elements to create the terminal device's context, saving signaling overhead between the access network device and the core network. In scenarios where network devices are deployed on satellites, frequent satellite handovers can also reduce signaling overhead.

[0008] In one possible implementation, the first state is a deactivated state, the second state is a connected state, and the network device is an access network device; the access network device receives a radio resource control (RRC) recovery request message from the terminal device, the RRC recovery request message including context information stored by the terminal device; the first message is an RRC recovery message.

[0009] In this implementation, the terminal device in the deactivated state can store its own context information and send this stored context information to the access network device during the RRC recovery process. This saves signaling overhead and reduces state transition latency, specifically: 1) Regardless of whether the access network device is deployed on a satellite, the access network device does not need to request the terminal device's context information from the access network device that previously served the terminal device. 2) Regardless of whether the access network device is deployed on a satellite, the access network device that previously served the terminal device can release the terminal device's context information after instructing the terminal device to enter the deactivated state, without the access network device needing to instruct the access network device that previously served the terminal device to release the terminal device's context information.

[0010] In one possible implementation, the RRC recovery request message further includes the deactivated state radio network temporary identifier (I-RNTI) of the terminal device, which is associated with the location of the terminal device; the access network device sends first indication information to the core network element based on the I-RNTI, which is used to indicate the activation of the I-RNTI.

[0011] In this implementation, when the access network device serving the terminal device switches over, the path from the core network to the access network device also needs to switch. After the switch, the new access network device informs the core network of the switching path. In scenarios where the access network device is deployed on satellites, satellite switching is frequent. If the new access network device informs the core network of the switching path after each switch, the signaling overhead between the access network device and the core network is extremely high. In this application, the I-RNTI is related to the geographical location of the terminal device. Regardless of how many satellite switches occur, when the core network element receives the first indication information, it can determine the location of the terminal device based on the I-RNTI and find the serving satellite at that location, thus saving signaling overhead between the access network device and the core network.

[0012] In satellite-based access network scenarios, the core network can predict when a terminal device will perform a satellite handover and the next satellite it will be on. When a satellite handover is imminent, the core network caches downlink data if available. After the handover, the cached downlink data is sent to the next satellite (access network device), eliminating the need for the next access network device to send its data forwarding address to the previous access network device.

[0013] In one possible implementation, the first state is an idle state, the second state is a connected state, and the network device is an access network device; the access network device receives a Radio Resource Control (RRC) establishment request message from the terminal device, the RRC establishment request message including context information stored by the terminal device; the first message is an RRC establishment message.

[0014] In one possible implementation, the access network device can also send the context information to the core network element, the context information being used to establish a connection between the core network element and the access network device.

[0015] In this implementation, the access network device sends the context information stored by the terminal device to the core network element, or the access network device informs the core network element of the context information for activating the terminal device. The core network element does not need to request the access network device to establish the context information for the terminal device again. The context information of the terminal device includes security information, which can encrypt and / or protect the integrity of uplink and downlink, without requiring security mode interaction between the access network device and the terminal device.

[0016] In one possible implementation, the network device is an access network device. Before receiving the context information stored by the terminal device from the terminal device, the access network device receives second indication information from a core network element. The second indication information is used to request activation of the terminal device. The access network device then sends a paging message to the terminal device, the paging message including third indication information, the third indication information being used to instruct the core network element to paging the terminal device.

[0017] In one possible implementation, the network device sends a fourth indication message to the terminal device, the fourth indication message being used to indicate that the terminal device stores the context information when the terminal device releases the RRC connection, enters a deactivated state, or enters an idle state; or, when the terminal device performs RRC connection restoration or RRC connection establishment, it sends the context information to the network device.

[0018] In one possible implementation, the network device is an access network device, which sends an RRC release message to the terminal device, the RRC release message including the fourth indication information.

[0019] In this implementation, the terminal device is instructed to send context information to the access network device by the indication information, which can more flexibly adapt to different scenarios.

[0020] In one possible implementation, after receiving the state information stored by the terminal device from the terminal device, the network device saves the context information of the terminal device.

[0021] In one possible implementation, the context information includes at least one of the following: terminal device identification information, terminal device session identification information, interface identifier, tunnel identifier, terminal device location information, quality of service information, billing information, security information, and terminal device capability information.

[0022] Secondly, embodiments of this application provide a communication method that can be applied to the terminal side, such as a terminal or a communication module within a terminal, or a circuit or chip (such as a modem chip, also known as a baseband chip, or a system-on-chip (SoC) chip or system-in-package (SIP) chip containing a modem core) responsible for communication functions within the terminal. Taking the application of this method to a terminal device as an example, in this method, the terminal device sends context information stored in the terminal device to a network device in a first state. The context information stored in the terminal device is used for the terminal device to transition from the first state to a second state. The terminal device receives a first message from the network device, which is used to instruct the terminal device to transition from the first state to the second state. The terminal device transitions from the first state to the second state. The first state is a deactivated state, an idle state, or a connected state. The second state is a deactivated state, an idle state, or a connected state. The first state and the second state are different.

[0023] The second aspect and its possible technical effects can be referenced in the first aspect and its possible technical effects, and will not be repeated here.

[0024] In one possible implementation, the first state is a deactivated state, the second state is a connected state, and the network device is an access network device; the terminal device sends a Radio Resource Control (RRC) recovery request message to the access network device, the RRC recovery request message including context information stored by the terminal device; the first message is an RRC recovery message.

[0025] In one possible implementation, the RRC recovery request message may also include the deactivated wireless network temporary identifier (I-RNTI) of the terminal device, which is associated with the location of the terminal device.

[0026] In one possible implementation, the first state is an idle state, the second state is a connected state, and the network device is an access network device; the terminal device sends a Radio Resource Control (RRC) establishment request message to the access network device, the RRC establishment request message including context information stored by the terminal device; the first message is an RRC establishment message.

[0027] In one possible implementation, the terminal device receives a paging message from the network device, the paging message including third indication information, the third indication information being used to instruct a core network element to paging the terminal device; based on the third indication information, the terminal device sends the context information stored by the terminal device to the network device.

[0028] In one possible implementation, the terminal device may also receive a fourth indication information from the network device, the fourth indication information being used to indicate any of the following: when the terminal device releases the RRC connection, enters a deactivated state, or enters an idle state, the terminal device stores the context information; or, when the terminal device performs RRC connection restoration or RRC connection establishment, the terminal device sends the context information to the network device.

[0029] In one possible implementation, the network device is an access network device, and the terminal device receives an RRC release message from the access network device, the RRC release message including the fourth indication information.

[0030] In one possible implementation, the terminal device stores the terminal device's context information upon releasing its connection with the network device.

[0031] In one possible implementation, the context information includes at least one of the following: terminal device identification information, terminal device session identification information, interface identifier, tunnel identifier, terminal device location information, quality of service information, billing information, security information, and terminal device capability information.

[0032] Thirdly, embodiments of this application provide a communication method that can be applied to the network side, such as access network devices, modules (e.g., circuits, chips, or chip systems) within the access network devices, or logical nodes, logical modules, or software capable of implementing all or part of the functions of the access network devices. Taking the application of this method to an access network device as an example, in this method, the source access network device sends a fifth indication message to the terminal device, the fifth indication message being used to instruct the terminal device to send the context information stored in the terminal device to the target access network device; the source access network device releases the context information of the terminal device.

[0033] In this method, the terminal device sends the context information stored in the terminal device to the target access network device, without requiring the source access network device to send the context information stored in the terminal device to the target access network device.

[0034] In one possible implementation, after the source access network device sends a cell handover command to the terminal device, it releases the context information of the terminal device.

[0035] In one possible implementation, the source access network device releases the context information of the terminal device at the first moment. The first moment is related to the satellite handover time. The source access network device can predict when the satellite handover will occur, and can determine the first moment based on the satellite handover time. For example, the first moment is no later than the satellite handover time.

[0036] In one possible implementation, the fifth indication information is further used to indicate the time at which the terminal device sends the context information to the target access network device (for ease of description, this time is referred to as the second time); or, the fifth indication information is specifically used to indicate that the terminal device sends the context information to the target access network device before the second time. The second time is no later than the first time.

[0037] In this implementation, the second time is related to the satellite handover time. The source access network device can predict when the satellite handover will occur. The source access network device can determine the second time based on the satellite handover time. For example, if the second time is not later than the satellite handover time, handover failure can be avoided.

[0038] In one possible implementation, the source access network device sends an RRC reconfiguration message to the terminal device, the RRC reconfiguration message including the fifth indication information; or, the source access network device sends a cell handover command to the terminal device, the cell handover command including the fifth indication information.

[0039] This implementation does not add any additional signaling overhead.

[0040] Fourthly, embodiments of this application provide a communication method that can be applied to the terminal side, such as a terminal or a communication module within a terminal, or a circuit or chip in the terminal responsible for communication functions (such as a modem chip, also known as a baseband chip, or a system-on-a-chip (SoC) chip or system-in-package (SIP) chip containing a modem core). Taking the application of this method to a terminal device as an example, in this method, the terminal device receives fifth indication information from a source access network device. The fifth indication information is used to instruct the terminal device to send the context information stored in the terminal device to a target access network device. Based on the fifth indication information, the terminal device sends the context information stored in the terminal device to the target access network device. The context information is used to switch to the target access network device.

[0041] In this method, the terminal device sends its stored context information to the target access network device, eliminating the need for the source access network device to send its stored context information to the target access network device. Furthermore, when the bearer link between the source and target access network devices is not ideal (e.g., high latency, limited bandwidth, instability, or even non-existent bearer link), having the terminal device inform the target access network device of its context information can improve the handover success rate.

[0042] In one possible implementation, the fifth indication information is further used to indicate the time at which the terminal device sends the context information to the target access network device (for ease of description, this time is referred to as the second time); or, the fifth indication information is specifically used to indicate that the terminal device sends the context information to the target access network device before the second time.

[0043] In one possible implementation, prior to the second moment, the terminal device sends its context information to the target access network device.

[0044] In this implementation, the second time is related to the satellite handover time. The source access network device can predict when the satellite handover will occur. The source access network device can determine the second time based on the satellite handover time. For example, if the second time is not later than the satellite handover time, handover failure can be avoided.

[0045] In one possible implementation, the terminal device sends the sequence number of the packet data convergence protocol-protocol data unit most recently received by the terminal device from the source access network device to the target access network device.

[0046] In this implementation, it is not necessary for the source access network device to send the data sequence number to the target access network device, which can save signaling overhead between access network devices.

[0047] Fifthly, embodiments of this application provide a communication method that can be applied to the terminal side, such as a terminal or a communication module in the terminal, or a circuit or chip in the terminal responsible for communication functions (such as a modem chip, also known as a baseband chip, or a system-on-a-chip (SoC) chip or system-in-package (SIP) chip containing a modem core). Taking the application of this method to a terminal as an example, in this method, the terminal device receives a paging message in a first state, the paging message being used to indicate that the terminal device transitions from the first state to a connected state; the first state is an idle state or a deactivated state; when the terminal device is not located in a first area, the context information stored by the terminal device is updated, the first area being used to indicate the effective area of ​​the context information stored by the terminal device.

[0048] In this method, by configuring the effective area of ​​context information, unnecessary context updates can be avoided, which can further reduce signaling overhead.

[0049] In one possible implementation, the paging message includes an identifier of the target cell; the terminal device may also send the context information to the target cell based on the identifier of the target cell.

[0050] In one possible implementation, the paging message includes the sixth indication information, which is used to indicate that the context information of the terminal device should be re-authenticated; the terminal device may also establish a re-authentication connection between the terminal device and the core network based on the sixth indication information, which is used by the core network to authenticate and / or update the context information of the terminal device.

[0051] Sixthly, a communication device is provided. The communication device can be a network device as described in the first aspect, possessing the functions of the network device. The communication device is, for example, a functional module within the network device, such as a baseband device or a chip system. Alternatively, the communication device can be a source access network device as described in the third aspect, possessing the functions of the source access network device. The communication device is, for example, a functional module within the source access network device, such as a baseband device or a chip system. Or, the communication device can be a terminal device as described in the second, fourth, or fifth aspect, possessing the functions of the terminal device. The communication device is, for example, a functional module within the terminal device, such as a baseband device or a chip system.

[0052] In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). The transceiver unit is capable of both transmitting and receiving functions. When the transceiver unit performs the transmitting function, it can be called a transmitting unit (sometimes also called a transmitting module), and when it performs the receiving function, it can be called a receiving unit (sometimes also called a receiving module). The transmitting unit and the receiving unit can be the same functional module, which is called the transceiver unit and can perform both transmitting and receiving functions; or, the transmitting unit and the receiving unit can be different functional modules, and the transceiver unit is a collective term for these functional modules.

[0053] In one possible implementation, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the network device described in the first aspect, or the functions of the source access network device described in the third aspect, or the functions of the terminal device described in the second, fourth, or fifth aspects.

[0054] A seventh aspect provides a communication device, including an interface circuit and one or more processors, optionally including a memory, with the one or more processors coupled to the memory. The memory stores a computer program, and the processors are coupled to the memory and the interface circuit. When the processor reads the computer program or instructions, it causes the communication device to execute the method performed by the network device in the first aspect, or the method performed by the source access network device in the third aspect, or the method performed by the terminal device in the second, fourth, or fifth aspect. For example, the interface circuit is used to receive signals from other communication devices besides the communication device and transmit them to the processor, or to send signals from the processor to other communication devices besides the communication device. The processor, through logic circuits or executable code instructions, implements the method performed by the network device in the first aspect, or the method performed by the source access network device in the third aspect, or the method performed by the terminal device in the second, fourth, or fifth aspect.

[0055] In one possible implementation, the communication device is a chip or chip system.

[0056] Eighthly, a communication device is provided, comprising one or more processors, optionally further comprising a memory; the one or more processors and the memory are coupled; the memory is used to store computer programs or instructions; the processor is used to execute part or all of the computer programs or instructions in the memory, wherein when the part or all of the computer programs or instructions are executed, they are used to implement the functions of the network device in the first aspect, or to implement the functions of the source access network device in the third aspect, or to implement the functions of the terminal device in the second, fourth, or fifth aspects.

[0057] In one possible implementation, the apparatus may further include a transceiver for transmitting signals processed by the processor or receiving signals input to the processor. The transceiver may perform the transmitting or receiving actions performed by the network device in the first aspect, or the transmitting or receiving actions performed by the source access network device in the third aspect, or the transmitting or receiving actions performed by the terminal device in the second, fourth, or fifth aspects.

[0058] In one possible implementation, the processing unit in the sixth aspect can be implemented by the processor, the storage unit in the sixth aspect can be implemented by the memory, and the transceiver unit in the sixth aspect can be implemented by the transceiver.

[0059] In one possible implementation, the communication device is a chip or chip system.

[0060] A ninth aspect provides a communication system comprising the network device of the first aspect and the terminal device of the second aspect, or comprising the source access network device of the third aspect and the terminal device of the fourth aspect, optionally further comprising a source target access network device that interacts with the terminal device. For example, the terminal device, network device, and source access network device can be implemented using the communication apparatus described in the seventh and eighth aspects.

[0061] In a tenth aspect, a computer-readable storage medium is provided for storing a computer program or instructions that, when executed, cause the methods of the first, second, third, fourth, or fifth aspects described above to be implemented.

[0062] Eleventhly, a computer program product containing instructions is provided, which, when run on a computer, enables the implementation of the methods described in the first, second, third, fourth, or fifth aspects above. Attached Figure Description

[0063] Figure 1a , Figure 1b , Figure 1c , Figure 1d and Figure 1e These are schematic diagrams of the architecture of a communication system provided in an embodiment of this application; Figure 1f A connection diagram illustrating the terminal device in different RRC states provided in the embodiments of this application; Figure 2 A schematic diagram illustrating the process of a terminal device transitioning from an RRC deactivation state to an RRC connection state, as provided in an embodiment of this application. Figure 3 This application provides a schematic diagram illustrating the process of a terminal device transitioning from an RRC idle state to an RRC connected state in an embodiment of the present application. Figure 4 A schematic diagram illustrating the process of cell handover for the terminal device provided in this application embodiment; Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 These are schematic flowcharts of the communication methods provided in the embodiments of this application; Figure 10 A schematic diagram of a device structure provided in an embodiment of this application; Figure 11 This is a schematic diagram of a device structure provided in an embodiment of this application. Detailed Implementation

[0064] The technical solution of this application can be applied to various wireless communication systems, including but not limited to fourth-generation (4G) mobile communication technology systems (also known as long term evolution (LTE) systems), fifth-generation (5G) mobile communication technology systems (also known as new radio (NR) systems), or future mobile communication systems, etc., without any specific limitations.

[0065] Furthermore, the technical solutions provided in this application can be applied to device-to-device (D2D) scenarios, such as NR-D2D scenarios, or to vehicle-to-everything (V2X) communication scenarios, such as NR-V2X scenarios. For example, they can be used in fields such as intelligent driving, assisted driving, or intelligent connected vehicles. As another example, the technical solutions provided in this application can also be applied to factory manufacturing scenarios.

[0066] Furthermore, the technical solutions provided in this application can be applied to scenarios including but not limited to: terrestrial cellular communication, non-terrestrial network (NTN), satellite communication, high altitude platform station (HAPS) communication, integrated access and backhaul (IAB) communication, and reconfigurable intelligent surface (RIS) communication.

[0067] Satellite communication systems include user equipment (UE) and network equipment. User equipment can also be referred to as user terminals, mobile stations, etc. Network equipment may include one or more satellites and ground station equipment, which can also be referred to as core network equipment. Satellites can be low Earth orbit (LEO) satellites, non-geostationary Earth orbit (NGEO) satellites, etc.

[0068] Figure 1a This is a schematic diagram of a satellite communication system according to an embodiment of this application. The satellite communication system includes satellites 101, 102, and 103. Each satellite can provide communication, navigation, and positioning services to terminal devices via multiple beams. In this scenario, the satellites are low Earth orbit (LEO) satellites. Satellite 103 is connected to ground station equipment. The satellites use multiple beams to cover the service area, and different beams can communicate via one or more of time division, frequency division, and space division. The satellites communicate wirelessly with terminal devices through broadcast communication signals and navigation signals, and can also communicate wirelessly with ground station equipment. The satellites mentioned in this embodiment can be satellite base stations, or may include orbital receivers or repeaters for relaying information, or network-side equipment mounted on the satellite.

[0069] Satellite communication systems include transparent and non-transparent satellite architectures. Transparent transmission, also known as bend-tube relay transmission, means that the signal only undergoes frequency conversion and amplification on the satellite; the satellite is transparent to the signal, as if it doesn't exist. Non-transparent transmission, also known as regenerative (on-board access / processing) transmission, means that the satellite has some or all of the base station functions. For example, satellites 101 and 102 in the diagram are non-transparent satellite architectures, while satellite 103 is a transparent satellite architecture. Furthermore, satellites can operate in earth-fixed, quasi-earth-fixed, or earth-moving modes.

[0070] like Figure 1b The diagram illustrates a transparent satellite architecture (RAN architecture). The satellite's role is radio frequency filtering, frequency conversion, and amplification. Essentially, the satellite primarily acts as a Layer 1 relay, regenerating and forwarding physical layer signals; it does not involve any higher protocol layers. Terminal devices access the access network equipment via the air interface. The satellite and ground stations (also known as non-terrestrial network gateways (NTN gateways)) forward signals between the terminal devices and the ground-based access network equipment. The access network equipment connects to the core network, and the core network communicates with the data network (DN).

[0071] like Figure 1c The diagram shows a regenerative satellite architecture without inter-satellite links (ISL), where the satellites function as access network equipment. For example... Figure 1d The diagram shows a regenerative satellite architecture with inter-satellite links, where the satellites function as access network equipment. For example... Figure 1e The regenerative satellite architecture shown has DU processing capabilities of the access network equipment, and the satellite has the DU functionality of the access network equipment.

[0072] In regenerative mode, terminal equipment and access network equipment communicate via air interface. The access network equipment, or its DU (Data Access Node) function, is deployed on the satellite. The access network equipment connects to the core network deployed on the ground via a ground station. The core network communicates with the data network (DN). The ground station is responsible for forwarding signaling and service data between the satellite-based access network equipment and the core network. Communication between the satellite-based access network equipment and the ground station is via the NG interface. Communication between access network equipment is via the Xn interface. For example, an inter-satellite link (ISL) exists between satellites to facilitate communication between access network equipment.

[0073] It is important to note that, in addition to carrying out the functions of the access network equipment, the regenerator can also carry out some or all of the core network functions, such as access and mobility management functions (AMF), session management functions (SMF), authentication server functions (AUSF), policy control functions (PCF), user plane functions (UPF), and other network elements.

[0074] The following is a description of the relevant terms used in this application: Network equipment is a device that provides voice or data connectivity to users. It can also be an Internet of Things (IoT) device, and is also referred to as a terminal, user equipment (UE), access terminal equipment, vehicle-mounted terminal, industrial control terminal, UE unit, UE station, mobile station, mobile station (MS), mobile terminal (MT), remote station, remote terminal equipment, mobile device, UE terminal equipment, terminal equipment, wireless communication equipment, UE agent, or UE device, etc. For example, terminal equipment includes handheld devices with wireless connectivity and vehicle-mounted equipment. Currently, terminal devices can include: mobile phones, tablets, customer-premises equipment (CPE), subscriber units, satellite phones, cellular phones, smartphones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, wireless data cards, personal digital assistant (PDA) computers, wireless modems, handsets, laptop computers, computers with wireless transceiver capabilities, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, head-mounted displays (HMDs), wireless terminals in industrial control, mobile internet devices (MIDs), in-vehicle terminal devices (e.g., cars, bicycles, electric vehicles, airplanes, ships, trains, high-speed trains, etc.), wireless terminals in self-driving cars, and remote medical devices. Wireless terminals in medical applications, smart grids, transportation safety, smart cities, smart homes, wearable devices (such as smartwatches, smart bracelets, pedometers, etc.), vehicles, drones, helicopters, airplanes, factory machinery / equipment, machine-type communication (MTC) terminals, ships, or robots, etc.Terminal devices can also be other devices with terminal functions. For example, a terminal device can also be a device that performs terminal functions in D2D communication.

[0075] Network equipment refers to nodes in a radio access network (RAN), also known as base stations, RAN nodes (or equipment), RAN entities, access network equipment, or access nodes. Examples of current access network equipment include: evolved NodeBs (eNodeBs), access points (APs), access points (APs) in wireless fidelity (Wi-Fi) systems, wireless relay nodes, wireless backhaul nodes, transmission points (TPs), next-generation node Bs (gNBs) in 5G networks, transmitting points (TPs), transmission reception points (TRPs), home base stations (e.g., home evolved NodeBs, or home Node Bs (HNBs)), macro base stations, micro base stations (also called small stations), relay stations, base band units (BBUs), or network equipment in communication systems evolving after 5G (6th Generation, 6G). Network equipment can also be other devices with network equipment functions, such as gNB, TRP, or TP in a 5G system, or one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system. Furthermore, network equipment can also be devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), Internet of Things (IoT), machine-to-machine (M2M) communication, or other communication systems. It can also include CU and DU in cloud radio access network (C-RAN) systems, and network equipment in non-terrestrial network (NTN) communication systems, i.e., it can be deployed on high-altitude platforms or satellites. This application does not specifically limit these aspects.

[0076] For example, in some possible network architectures, network devices can be CUs, DUs, CUs (control plane, CP), CUs (user plane, UP), or radio units (RUs), etc. CUs and DUs can be configured separately or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio equipment or radio units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs). In this network architecture, signaling generated by the CU can be sent to the terminal device via the DU, or signaling generated by the terminal device can be sent to the CU via the DU. The DU can directly pass the signaling through protocol layer encapsulation without parsing it to the terminal device or CU. In this network architecture, the CU is classified as a network device on the radio access network side; alternatively, the CU can also be classified as a network device on the core network side, and this application does not impose any limitations on this. For example, the functions of the PDCP layer and above are located in the CU, while the functions of the protocol layers below the PDCP layer (such as the RLC layer and MAC layer) are located in the DU. It is understood that the above division of the processing functions of the CU and DU according to protocol layers is merely an example, and other methods can also be used. For instance, the functions of the protocol layers above the RLC layer could be located in the CU, and the functions of the protocol layers below the RLC layer could be located in the DU. Alternatively, the CU or DU could be divided into those with functions from more protocol layers, or even those with partial processing functions from protocol layers.

[0077] It is understood that CU (or CU-CP and CU-UP), DU, or RU may have different names in different systems, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. 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 modules and hardware modules.

[0078] Ground station equipment can also be referred to as core network equipment. Ground station equipment includes, for example, equipment in the core network (CN) of existing mobile communication architectures (such as the 3GPP access architecture of 5G networks) or equipment in the core network of future mobile communication architectures. The core network, as the bearer network, provides the interface to the data network, providing user equipment (UE) with communication connections, authentication, management, policy control, and the ability to carry data services. The CN can further include: access and mobility management functions (AMF), session management functions (SMF), authentication server functions (AUSF), policy control functions (PCF), user plane functions (UPF), and other network elements.

[0079] The access management network element (also known as the mobility management network element) is a control plane network element provided by the operator's network. It is responsible for access control and mobility management of terminal equipment accessing the operator's network, including functions such as mobility state management, allocation of temporary user identities, authentication, and user management. In 5G communication systems, this access management network element can be an access and mobility management function (AMF) network element. In future communication systems, the access management network element may still be an AMF network element, or it may have other names; this application does not limit its scope.

[0080] The session management network element is primarily responsible for session management in mobile networks, such as session establishment, modification, and release. Specific functions include assigning IP addresses to users and selecting user plane network elements that provide packet forwarding capabilities. In 5G communication systems, this session management network element can be a session management function (SMF) network element. In future communication systems, the session management network element may still be an SMF network element, or it may have other names; this application does not impose any limitations on this.

[0081] User plane network elements are responsible for forwarding and receiving user data in terminal devices. They can receive user data from the data network and transmit it to the terminal device through the access network equipment; user plane network elements can also receive user data from the terminal device through the access network equipment and forward it to the data network. The transmission resources and scheduling functions that provide services to the terminal device in the user plane network element are managed and controlled by the SMF network element. In 5G communication systems, this user plane network element can be a user plane function (UPF) network element. In future communication systems, the user plane network element can still be a UPF network element, or it can have other names; this application does not limit this.

[0082] Data Networks (DNs) can deploy various services, providing data and / or voice services to terminal devices. For example, a DN might be the private network of a smart factory. Sensors installed in the workshop can act as terminal devices. The DN deploys both sensors and a control server, with the control server providing services to the sensors. Sensors can communicate with the control server, receive instructions, and transmit collected sensor data accordingly. Another example is a DN serving as an internal office network for a company. Employees' mobile phones or computers can act as terminal devices, accessing information and data resources within the company's internal network.

[0083] The radio resource control (RRC) status of a terminal device reflects its access stratum (AS) connectivity. AS connection refers to the signaling connection between the terminal device and the access network equipment. AS signaling interaction establishes a signaling path between the UE and the core network, enabling non-access stratum (NAS) signaling interaction. In other words, AS connection paves the way for NAS signaling interaction.

[0084] Figure 1fThis diagram illustrates the connection relationships between the terminal device, access network device, and core network under different terminal device states. The three RRC states of the terminal device are: RRC connected, RRC idle, and RRC inactive. In the RRC connected state, the terminal device and access network device establish an RRC connection, and the access network device and core network establish an NG connection. The terminal device, access network device, and core network all maintain the terminal device's context information. In the RRC idle state, the terminal device and access network device disconnect the RRC connection, and the access network device and core network also disconnect the NG connection. The terminal device, access network device, and core network no longer maintain the terminal device's context information. In the RRC deactivation state, the terminal device and the access network device disconnect the RRC connection, while the access network device and the core network maintain the NG connection. The terminal device suspends data processing, but the access network device and the core network still maintain the context information of the terminal device. Simply put, the air interface state of the terminal device in the RRC deactivation state is similar to that in the RRC idle state, but from the perspective of the core network, the terminal device in the RRC deactivation state is still in the connection management (CM) connection state.

[0085] Figure 2 This is a schematic diagram illustrating the process of a terminal device transitioning from the RRC deactivation state to the RRC connection state.

[0086] Step 200: The UE in RRC_idle, CM_connected state performs random access and accesses the first access network device.

[0087] Step 201: The UE sends an RRC resume request to the first access network device, and the first access network device receives the RRC resume request accordingly.

[0088] The RRC recovery request includes: the UE's identifier, and the inactive radionetwork temporary identifier (I-RNTI) assigned to the terminal device by the second access network device (lastserving gNodeB) that previously served the terminal device. The I-RNTI contains the identity information of the last serving gNodeB.

[0089] Step 202: The first access network device sends a retrieve UE context request to the second access network device, and the second access network device receives the retrieve UE context request accordingly.

[0090] The UE Context Retrieval Request is used to request the second access network device (last serving gNodeB) to provide the UE's context information. The UE Context Retrieval Request includes the UE's identifier.

[0091] The first access network device parses the identity information of the second access network device (lastsgNodeB) from the I-RNTI in the RRC recovery request, and based on the identity information of the second access network device, sends a UE context retrieval request to the second access network device. Step 203: The second access network device sends a retrieve UE context response to the first access network device, and the second access network device receives the retrieve UE context response accordingly.

[0092] Retrieve UE context information from the UE context response.

[0093] The second access network device locates the UE's context information based on the UE's identifier and sends the located UE context information to the first access network device. The first access network device then saves the received UE context information.

[0094] Step 204: The first access network device sends an RRC resume message to the UE.

[0095] Based on the UE's context information obtained from the second access network device, the first access network device determines that the UE can restore the RRC connection, and then sends an RRC restoration message to the UE.

[0096] After receiving the RRC recovery message, the UE transitions from the RRC deactivation state to the RRC connection state (UE in RRC_connected, CM_connected).

[0097] Step 205: The UE sends an RRC resume complete message to the first access network device.

[0098] Optionally, in step 206: the first access network device sends XN-U address indication information to the second access network device to provide a data forwarding address to the second access network device.

[0099] The second access network device forwards downlink data based on this address, which can avoid losing downlink data of terminal devices buffered in the second access network device.

[0100] Step 207: The first access network device sends a path switch request to the AMF, which includes information about the first access network device.

[0101] Step 208: The AMF sends a path switch response to the first access network device to indicate agreement to switch paths.

[0102] After the path switch, the uplink and downlink data from the terminal device to the core network element are forwarded by the first access network device and no longer need to be forwarded by the second access network device.

[0103] Step 209: The first access network device sends a UE context release message to the second access network device.

[0104] After receiving the UE context release message, the second access network device releases the context information of the corresponding UE based on the UE identifier in the release message.

[0105] Figure 3 This is a schematic diagram illustrating the process of a terminal device transitioning from the RRC idle state to the RRC connected state.

[0106] Step 301: The UE in RRC idle state (UE in RRC_idle, CM_idle) sends an RRC setup request to the access network device.

[0107] The RRC establishment request includes the UE's identifier.

[0108] Step 302: The access network device sends an RRC setup message to the UE.

[0109] After receiving the RRC establishment request message, the access network device establishes the UE's context information based on the UE's identifier. The context information includes information such as the core network identifier related to the UE, the reason for the access request, and the access level. Then, it sends an RRC establishment message to the UE.

[0110] After receiving the RRC establishment message, the UE transitions from the RRC idle state to the RRC connected state (UE in RRC_connected, CM_idle).

[0111] Step 303: The UE sends an RRC setup complete message to the access network equipment.

[0112] Step 304: The access network device sends an initial UE message to the AMF.

[0113] The access network device assigns a dedicated RAN-UE-NGAP-ID (NG Application Protocol (NGAP)) to the UE. The access network device selects an AMF and sends the NAS carried in the RRC establishment completion message to the AMF through the initial UE message, triggering the NG-C connection establishment. The NAS message includes the public land mobile network (PLMN) identifier, the registered AMF, handover information, etc.

[0114] For example, access network devices can select AMF nodes based on selectedPLMN-Identity, registeredAMF, and s-nssai-list.

[0115] At this point, CM_idle changes to CM_connected.

[0116] Optionally, step 305: The access network device transparently transmits the NAS direct transmission message between the UE and the AMF.

[0117] Step 306: The AMF sends an initial context setup request message to the access network device to start the initial context setup process.

[0118] Step 307: The access network device sends a security mode command message to the UE, notifying the UE to initiate the integrity protection and encryption process. Subsequently, downlink encryption is initiated. The security mode command specifies the integrity protection and encryption algorithms. The initial context establishment request carries security information, such as the key and algorithm.

[0119] Step 307a: The UE sends a security mode complete message to the access network device.

[0120] The UE derives a key based on the integrity protection and encryption algorithm indicated in the security mode command message, and then replies with a security mode completion message to the access network device. Afterward, uplink encryption is initiated.

[0121] Step 308: The access network device sends an RRC reconfiguration message to the UE, instructing the establishment of a signaling radio bearer (SRB) (e.g., SRB2) and a data radio bearer (DRB).

[0122] Step 308a: The UE sends an RRC reconfiguration complete message to the access network device.

[0123] Step 309: The access network device sends an initial context setup response message to the AMF, indicating that the context setup is complete.

[0124] The initial context response contains context information of the terminal device, including but not limited to PDU session context, security key, mobility constraint list, UE radio capabilities, and UE security capabilities.

[0125] Figure 4 A schematic diagram illustrating the process of cell handover for terminal devices.

[0126] Step 400: The core network sends measurement and control information to the source access network equipment.

[0127] Step 401: The UE sends measurement reports (e.g., L3 measurement reports) to the source access network device.

[0128] For example, the source access network device sends measurement control information to the UE. The measurement control information includes one or more of the following: measurement objects (same frequency / different frequency), measurement report configuration, and measurement gap configuration.

[0129] The UE measures the cell signal quality based on the measurement and control information, and reports the L3 measurement results (i.e., measurement report) to the source access network equipment.

[0130] The reporting method can be periodic reporting or event-triggered reporting. In event-triggered reporting, the reporting conditions are usually configured as the serving cell signal quality being less than a first threshold and / or the neighboring cell signal quality being greater than a second threshold.

[0131] Step 402: Lower layer triggered mobility (LTM) decision.

[0132] For example, the source access network equipment makes LTM handover strategies and target cell / frequency decisions based on L3 measurement results, such as selecting suitable neighboring cells and exchanging user handover-related context information, admission control information, and reserved resources.

[0133] Step 403: The source access network device sends a handover request to the target access network device.

[0134] For example, the source access network device sends a handover request to the access network devices where the multiple target cells determined in step 402 are located. The handover request includes the context information of the terminal device in the source access network device (or source cell).

[0135] Step 404: The target access network device performs access control.

[0136] After receiving the handover request, the target access network device performs admission control and, after admission, allocates UE instances and transmission resources.

[0137] Step 405: The target access network device sends a handover request acknowledgement to the source access network device, allowing the handover access.

[0138] The handover request confirmation message includes RRC configuration information for multiple cells.

[0139] Step 406: The source access network device sends an RRC reconfiguration message to the UE. The RRC reconfiguration message carries the RRC configuration information of the target cell.

[0140] Step 407: The UE sends an RRC reconfiguration complete message to the source access network device to indicate that it has received the RRC configuration information of the candidate cell.

[0141] For example, the UE saves the RRC configuration information of the target cell.

[0142] Step 408: The UE performs L1 measurements and periodically / event-triggered reports the L1 measurement results (also known as L1 measurement reports).

[0143] Optionally, the UE may perform downlink synchronization (step 408a) and uplink synchronization (step 408b) with the target cell in advance.

[0144] Step 409: The source access network device determines to perform LTM handover based on the L1 measurement results of the UE.

[0145] Step 410: The source access network device sends an LTM cell switch command to the UE.

[0146] Step 411: The source access network device sends an SN status transfer message to the target access network device.

[0147] For example, after receiving the handover request confirmation message, the source access network device sends an SN status transfer message to the target access network device via the X2 (or S1) link. This message contains the uplink and downlink sequence number (SN) and hyperframe number of the terminal in the serving cell's packet data convergence protocol (PDCP).

[0148] Step 412: The UE switches to the target access network device based on the LTM cell handover command, and the LTM handover is completed.

[0149] Step 413: After the UE successfully hands over, it sends an RRC reconfiguration complete message to the target access network device to indicate that the handover was successful.

[0150] Step 414: The target access network device sends a handover success indication message to the source access network device.

[0151] Step 415: The target access network device sends a path switch request message to the core network to notify that the UE has changed its serving cell. This message carries the target cell identifier and the list of protocol data unit sessions to be switched.

[0152] Step 416: After receiving the message, the core network performs UPF path translation. For example, it updates the downlink (user plane General Packet Radio Service (GPRS) Tunneling Protocol) (GTPU) data plane, modifying the GTPU address on the RAN side to the address of the target access network device.

[0153] Step 417: The core network replies to the target access network device with a path conversion request confirmation message.

[0154] Step 418: The target access network device sends a UE context release message to the source access network device. After receiving the message, the source access network device releases the context information of the switched UE.

[0155] In non-terrestrial networks, satellites serving terminal devices frequently switch over. When network devices (access network devices and / or core network elements) are deployed on satellites, the network devices serving the terminal devices also switch over frequently. Due to the frequent switching of network devices, the signaling overhead on the network side is extremely high. For example, when a satellite serving a terminal device switches over, the satellite before the switch informs the satellite after the switch of the context information of the terminal device, resulting in high signaling overhead between the network sides; or, if access network devices are deployed on satellites, the core network informs the satellite after the switch (access network devices) of the context information of the terminal device, resulting in extremely high signaling overhead between the access network devices and the core network; in addition, when a satellite switches over, the path from the core network to the access network devices also switches, and the access network devices inform the core network of the new path, resulting in extremely high signaling overhead between the access network devices and the core network.

[0156] Based on this, this application provides a communication method in which the terminal device sends its stored context information to the network device, eliminating the need for the network device before handover to send the terminal device's context information to the network device after handover, thus saving signaling overhead between network devices; or, eliminating the need for signaling interaction between the access network device and the core network device to create the terminal device's context, thus saving signaling overhead between the access network device and the core network. In scenarios where network devices are deployed on satellites, frequent satellite handovers can also reduce signaling overhead.

[0157] The relevant terms used in the embodiments of this application will be explained below. It should be noted that these explanations are for the purpose of making the embodiments of this application easier to understand, and should not be regarded as a limitation on the scope of protection claimed by this application.

[0158] 1) Context information can also be called state information or state replica information.

[0159] Including but not limited to one or more of the following: The terminal device's identification information, the terminal device's session-related information (including but not limited to session identification information), interface identifiers such as F1, Xn, E1, and NG, tunnel identifiers (such as tunnel identifiers under the generic tunneling protocol (GTP), terminal device's location information, quality of service information, billing information, security information, and terminal device's capability information, etc.

[0160] The location information of the terminal device includes, but is not limited to, one or more of the following: the cell identifier, tracking area identifier, wave position identifier, area identifier, IP address, or other identifiers containing geographical location.

[0161] Quality of service (QoS) information includes, but is not limited to, one or more of the following: QoS level, priority, forwarding rules, and mapping rules between QoS and data radio bearer (DRB).

[0162] Billing information includes, but is not limited to, one or more of the following: network usage reports, contracted packages, etc.

[0163] Security information includes, but is not limited to, one or more of the following: keys, authentication vectors, access policies, etc.

[0164] The capability information of the terminal device includes, but is not limited to, one or more of the following: terminal device type, power level, supported handover type, number of supported hybrid automatic repeat request (HARQ) processes, supported carrier aggregation (CA), and dual-connectivity (DC).

[0165] 2) Deactivation state, also known as inactive state, RRC deactivation state, RRC inactive state; idle state, also known as RRC idle state; connection state, also known as RRC connection state.

[0166] When a terminal device or network device experiences an RRC reconfiguration failure, handover failure, wireless link failure, or integrity protection failure, it will initiate an RRC connection release process, which will put the terminal device into an idle state or a deactivated state.

[0167] The above Figure 1f The previous description stated that when the terminal device is in a deactivated state or an idle state, the terminal device no longer maintains the terminal device's context information; however, in this application, the terminal device can maintain the terminal device's context information when it is in a deactivated state or an idle state.

[0168] The above Figure 1f The previous description stated that when the terminal device is in an idle state, the core network no longer maintains the context information of the terminal device; in this application, when the terminal device is in an idle state, the core network may or may not maintain the context information of the terminal device.

[0169] 3) The inactive radio network temporary identifier (I-RNTI) is typically generated and assigned to the terminal device by the access network device that previously served the terminal device (i.e., the access network device the terminal device connected to before entering the deactivated state). The I-RNTI is used to uniquely identify the terminal device in the deactivated state. When the terminal device recovers from the deactivated state to the connected state, it sends the I-RNTI to the access network device. Based on the I-RNTI, the access network device requests the terminal device's context information from the access network device that previously served the terminal device. In this application, the I-RNTI is associated with the geographical location of the terminal device, or the I-RNTI includes information about the geographical location of the terminal device.

[0170] To better illustrate the embodiments of this application, the methods provided by the embodiments of this application are described below with reference to the accompanying drawings. Unless otherwise specified below, the steps indicated by dashed lines in the accompanying drawings corresponding to the various embodiments of this application are optional steps. It should be noted that the technical details of the multiple embodiments provided in this application can be referenced to each other, each embodiment described below can exist independently, and multiple embodiments can also be combined with each other as an embodiment in the absence of logical errors.

[0171] Figure 5 A flowchart of a communication method is provided. Figure 5 The method is illustrated using network devices and terminal devices as examples of the execution entities in this interactive illustration, but this application does not limit the execution entities in the interactive illustration. For example, the method executed by the network device in this application can also be implemented by modules (such as circuits, chips, or chip systems) in the network device, or by logical nodes, logical modules, or software that can implement all or part of the functions of the network device; in addition, the aforementioned network device can be replaced by access network devices or core network elements. The method executed by the terminal device in this application can also be implemented by the communication module in the terminal device, or by the circuits or chips (such as modem chips (also known as baseband chips), or (SoC) chips containing modem cores, or (SIP) chips) in the terminal device responsible for communication functions.

[0172] like Figure 5 As shown, the method may include the following steps: Step 501: The terminal device sends the context information stored in the terminal device to the network device, and the network device receives the context information stored in the terminal device from the terminal device.

[0173] In one possible scenario, when a terminal device is performing a state (RRC state) transition, it sends the context information stored by the terminal device to the network device.

[0174] For example, a terminal device in the first state sends context information stored in the terminal device to a network device, and the network device receives the context information stored in the terminal device from the terminal device.

[0175] The context information stored by the terminal device is used for the terminal device to transition from a first state to a second state; the first state is one of the following: deactivated state, idle state, or connected state; the second state is one of the following: deactivated state, idle state, or connected state; the first state and the second state are different. The first state can also be called the first RRC state, and the second state can also be called the second RRC state. For example, when the first state is the idle state, the second state can be the connected state; when the first state is the deactivated state, the second state can be the connected state.

[0176] Furthermore, the active state can be divided into two more granular states: a first active state and a second active state. When the terminal device is in the first active state, it does not store context information; the network side stores the context information. When the terminal device is in the second active state, it stores the context information. The idle state can also be divided into two more granular states: a first idle state and a second idle state. When the terminal device is in the first idle state, it does not store context information; the network side stores the context information. When the terminal device is in the second idle state, it stores the context information. The connected state can also be divided into two more granular states: a first connected state and a second connected state. When the terminal device is in the first connected state, it does not store context information; the network side stores the context information. When the terminal device is in the second connected state, it stores the context information.

[0177] The first state can be one of the following: a second active state, a second idle state, or a second connected state. The second state can be one of the following: a second connected state, a first active state, or a first idle state.

[0178] By using terminal devices / network devices to collaboratively store context information on demand, signaling overhead can be reduced, and different scenario requirements can be further adapted (such as different caching capabilities and security levels of terminal devices / network devices).

[0179] Optionally, in step 502: the network device sends a first message to the terminal device based on context information; correspondingly, the terminal device in the first state receives the first message; the first message is used to instruct the terminal device to transition from the first state to the second state.

[0180] Optionally, step 503: The terminal device transitions from the first state to the second state.

[0181] For example, the terminal device transitions from a first state to a second state based on the first message.

[0182] Step 501 can also be applied to other scenarios, such as access network device switching and cell switching.

[0183] In this method, the terminal device sends its stored context information to the network device, eliminating the need for the network device before handover to send the terminal device's context information to the network device after handover, thus saving signaling overhead between network devices. Alternatively, there is no need for signaling interaction between the access network device and the core network device to create the terminal device's context, saving signaling overhead between the access network device and the core network. In scenarios where network devices (such as the access network and / or core network) are deployed in satellites, when a satellite serving the terminal device undergoes handover, there is also no need for the satellites (network devices) to exchange the terminal device's context information.

[0184] The following section provides a detailed introduction to the different state transitions.

[0185] Figure 6 This application provides a schematic diagram illustrating the process of a terminal device transitioning from a deactivated state to a connected state. Figure 6 This application illustrates the method using core network elements, access network equipment, and terminal equipment as examples of the execution entities in the interaction illustration. However, this application does not limit the execution entities in the interaction illustration. For example, the method executed by the access network equipment in this application can also be implemented by modules (e.g., circuits, chips, or chip systems) in the access network equipment, or by logical nodes, logical modules, or software that can implement all or part of the functions of the access network equipment; the method executed by the core network elements in this application can also be implemented by modules (e.g., circuits, chips, or chip systems) in the core network elements, or by logical nodes, logical modules, or software that can implement all or part of the functions of the core network elements; the method executed by the terminal equipment in this application can also be implemented by the communication module in the terminal equipment, or by the circuit or chip responsible for communication functions in the terminal equipment (such as a modem chip (also known as a baseband chip), or a SoC chip containing a modem core, or a system-in-package (SIP) chip).

[0186] Step 601: The terminal device in the deactivated state sends the context information stored by the terminal device to the access network device, and the access network device receives the context information stored by the terminal device accordingly.

[0187] For example, before step 601, the terminal device is in the RRC deactivation state and the CM connection state.

[0188] In one possible implementation, the terminal device in the deactivated state sends an RRC recovery request message to the access network device, and the access network device receives the RRC recovery request message accordingly. The RRC recovery request message includes context information stored by the terminal device. The terminal device sends the context information to the access network device in the RRC recovery request message without requiring additional signaling and thus incurring no signaling overhead.

[0189] In another possible implementation, the message carrying context information differs from the RRC recovery request message. For example, after a deactivated terminal device sends an RRC recovery request to the access network device, it sends the context information stored by the terminal device to the access network device. By carrying the context information stored by the terminal device in a separate message, the message format of the RRC recovery request message can be changed without modifying it.

[0190] For example, a terminal device in a deactivated state sends an RRC recovery request message to an access network device. This message carries an indication that instructs the terminal device to send its stored context information to the access network device. For instance, this indication occupies 1 bit. A first value indicates that the terminal device is sending its stored context information, while a second value indicates that the terminal device is not sending it. Upon receiving the RRC recovery request message, the access network device, based on this indication, understands that it does not need to request the terminal device's context information from the access network device that previously served the terminal device.

[0191] For example, the protocol stipulates that in a certain scenario (such as when the access network device is deployed on a satellite), a terminal device in a deactivated state sends the context information stored by the terminal device to the access network device. Even if the RRC recovery request message does not carry the aforementioned indication information, the access network device does not need to request the context information of the terminal device from the access network device that previously served the terminal device.

[0192] Step 602: The access network device sends an RRC recovery message (corresponding to the first message in step 502) to the terminal device based on the context information stored in the terminal device; accordingly, the terminal device in the deactivated state receives the RRC recovery message.

[0193] Access network devices can also save context information stored by terminal devices.

[0194] Step 603: The terminal device transitions from the deactivated state to the connected state based on the RRC recovery message.

[0195] For example, after step 603, the terminal device is in RRC connection state or CM connection state.

[0196] Optionally, step 604: The terminal device sends an RRC recovery complete message to the access network device to indicate that the terminal device has switched to the connected state.

[0197] In this method, the terminal device in the deactivated state can store its own context information and send the stored context information to the access network device during the RRC recovery process. This can save signaling overhead and reduce state transition latency, as detailed below: 1) Regardless of whether the access network equipment and / or core network equipment are deployed on a satellite, the access network equipment does not need to request the context information of the terminal equipment from the access network equipment that previously served the terminal equipment. Figure 2 For comparison, the following can be omitted. Figure 2 Steps 202 and 203 in the process.

[0198] 2) Regardless of whether the access network equipment and / or core network equipment are deployed on a satellite, the access network equipment that previously served the terminal equipment can release the terminal equipment's context information after instructing the terminal equipment to enter the deactivation state. This is without the access network equipment needing to instruct the previously serving access network equipment to release the terminal equipment's context information. Figure 2 For comparison, the following can be omitted. Figure 2 Step 209 in the process.

[0199] In terrestrial networks, the core network cannot predict when a terminal device will switch access network devices, nor can it predict which access network device it will switch to. If downlink data is available, the core network sends the downlink data to the access network device that was serving the terminal device before the switch. After the switch, the new access network device sends its data forwarding address to the previous access network device, so that the previous access network device can send its buffered downlink data to the new access network device, which then forwards it to the terminal device. This process is similar to... Figure 2 This corresponds to step 206 in the text.

[0200] In satellite-based access network scenarios, the core network can predict when a terminal device will perform a satellite handover and the next satellite after the handover. When a satellite handover is imminent, the core network caches downlink data if available. After the handover, the cached downlink data is sent to the next satellite (access network device), eliminating the need for the next access network device to send its data forwarding address to the previous access network device. Figure 2 For comparison, the following can be omitted. Figure 2 Step 206 in the process saves signaling overhead.

[0201] Following step 604 or 602, one possible implementation is that the access network device can request a path handover from the core network, for example, by performing... Figure 2The process of steps 207 and 208 in the process.

[0202] Another possible implementation is that the RRC recovery request message in step 601 includes the I-RNTI of the terminal device, the I-RNTI of the terminal device is associated with the location of the terminal device, or the I-RNTI includes the location information of the terminal device, and the core network can realize path switching through the I-RNTI.

[0203] like Figure 6 As shown, optionally, step 605: The access network device sends a first indication message to the core network element (e.g., the access management network element AMF) based on the I-RNTI. The first indication message is used to indicate the activation of the I-RNTI.

[0204] The first indication information includes I-RNTI. Optionally, the first indication information may also include the I-RNTI activation time, time period, timer, etc. The core network can also determine the I-RNTI activation time, time period, timer, etc. itself.

[0205] Optionally, after receiving the first indication information, the core network element can activate the context information of the terminal device and, based on the I-RNTI, determine the location of the terminal device. Based on the location of the terminal device, it can determine the serving satellite for that location and achieve communication with the terminal device through a new path from the core network to the serving satellite.

[0206] Optionally, in certain scenarios (such as network-side paging terminal devices), access network devices exchange I-RNTIs. For example, an access network device that previously served a terminal device sends an I-RNTI to the access network device that is currently serving the terminal device, without the terminal device needing to send an I-RNTI to the access network device.

[0207] When an access network device serving a terminal device switches over, the path from the core network to the access network device also needs to be switched. After the access network device switches over, the new access network device informs the core network of the switching path (e.g., ...). Figure 2 (Steps 207 and 208 in the original text). In scenarios where access network equipment is deployed on satellites, satellite handovers are frequent. If, after each handover, the new access network equipment informs the core network of the handover path, the signaling overhead between the access network equipment and the core network is extremely high. In this application, the I-RNTI is related to the location of the terminal equipment. Regardless of how many satellite handovers occur, when the core network element receives the first indication information, it can determine the location of the terminal equipment based on the I-RNTI and locate the serving satellite for that location. Figure 2 In comparison, steps 207 and 208 can be omitted, saving signaling overhead between the access network equipment and the core network.

[0208] Figure 7 This application provides a schematic diagram illustrating the process by which a terminal device transitions from an idle state to a connected state. Figure 7 This application illustrates the method using core network elements, access network equipment, and terminal equipment as examples of the execution entities in the interaction illustration. However, this application does not limit the execution entities in the interaction illustration. For example, the method executed by the access network equipment in this application can also be implemented by modules (e.g., circuits, chips, or chip systems) in the access network equipment, or by logical nodes, logical modules, or software that can implement all or part of the functions of the access network equipment; the method executed by the core network elements in this application can also be implemented by modules (e.g., circuits, chips, or chip systems) in the core network elements, or by logical nodes, logical modules, or software that can implement all or part of the functions of the core network elements; the method executed by the terminal equipment in this application can also be implemented by the communication module in the terminal equipment, or by the circuit or chip responsible for communication functions in the terminal equipment (such as a modem chip (also known as a baseband chip), or a SoC chip containing a modem core, or a system-in-package (SIP) chip).

[0209] Step 701: The terminal device in the idle state sends the context information stored by the terminal device to the access network device, and the access network device receives the context information stored by the terminal device accordingly.

[0210] For example, before step 701, the terminal device is in RRC idle and CM idle state.

[0211] In one possible implementation, an idle terminal device sends an RRC establishment request message to an access network device, and the access network device receives the RRC establishment request message. The RRC establishment request message includes context information stored by the terminal device. The terminal device sends the context information to the access network device in the RRC establishment request message without requiring additional signaling and thus incurring no signaling overhead.

[0212] In another possible implementation, the message carrying the context information stored by the terminal device differs from the RRC establishment request message. For example, after an idle terminal device sends an RRC establishment request to the access network device, it sends the context information stored by the terminal device to the access network device. By carrying the context information stored by the terminal device through a separate signaling, the message format of the RRC establishment request message does not need to be modified.

[0213] For example, a terminal device in an idle state sends an RRC establishment request message to an access network device. The RRC establishment request message carries an indication message, which is used to instruct the terminal device to send the context information stored by the terminal device to the access network device. For example, the indication message occupies 1 bit. When the bit is of the first value, it means that the terminal device sends the context information stored by the terminal device to the access network device. When the bit is of the second value, it means that the terminal device does not send the context information stored by the terminal device to the access network device.

[0214] For example, the protocol stipulates that in a certain scenario (such as when the access network equipment is deployed on a satellite), the terminal equipment in the idle state sends the context information stored by the terminal equipment to the access network equipment, and the RRC establishment request message does not carry the aforementioned indication information.

[0215] Step 702: The access network device sends an RRC establishment message (corresponding to the first message in step 502) to the terminal device based on the context information; accordingly, the terminal device in the idle state receives the RRC establishment message.

[0216] Access network devices can also save context information stored by terminal devices.

[0217] Step 703: The terminal device establishes a message based on RRC and transitions from the idle state to the connected state.

[0218] For example, after step 703, the terminal device is in RRC connected state and CM idle state.

[0219] Optionally, in step 704: the terminal device sends an RRC establishment completion message to the access network device to indicate that the terminal device has switched to the RRC connection state.

[0220] Following step 702 or 704, step 705 is executed: the access network device sends the context information stored by the terminal device to the core network element (e.g., the access management network element AMF); correspondingly, the core network element receives the context information stored by the terminal device. The core network element may also save the received context information stored by the terminal device.

[0221] In another possible implementation, when the terminal device enters the idle state, the core network element does not release the terminal device's context information. For example, the terminal device's context information can be deactivated. Subsequently, when the terminal device transitions to the connected state, the core network element activates the terminal device's context information. Step 705 above can be replaced by: the access network device sending indication information to the core network element. This indication information indicates the activation of the terminal device's context information. The indication information includes the terminal device's identifier, and optionally, it also includes the activation time, time period, timer, etc. The core network element can also determine the activation time, time period, timer, etc., of the context information itself.

[0222] For example, the access network device sends the initial UE transmission message to the core network element (see reference). Figure 3 In step 304), the initial UE transmission message includes context information stored by the terminal device or indication information for activating the context information of the terminal device. Alternatively, the message carrying context information or activation indication information may be a new message, different from the initial UE transmission message. In this case, it is not necessary for the access network device to send the initial UE transmission message to the core network element.

[0223] After receiving context information or activation indication information stored by the terminal device, the core network element establishes a connection between the access network device and the core network, such as activating / configuring identification and configuration information related to the NG interface.

[0224] For example, after step 705, the terminal device is in RRC connection state or CM connection state.

[0225] The access network device sends the context information stored by the terminal device to the core network element; or, the access network device informs the core network element of the context information for activating the terminal device, and the core network element no longer needs to request the access network device to establish the UE's context information. Figure 3 In contrast, steps 305, 306, and 309 can be omitted.

[0226] The context information of the terminal device includes security information, which can encrypt and / or protect the integrity of uplink and downlink signals. Figure 3 In contrast, steps 307 and 307a can be omitted.

[0227] The order of steps 705 and 704 is not limited, nor is the order of steps 705 and 706.

[0228] After steps 702, 704, and 705, step 706 is executed: the access network device sends an RRC reconfiguration message to the terminal device, instructing the establishment of a signaling radio bearer SRB (e.g., SRB2) and a data radio bearer DRB.

[0229] Step 707: The terminal device sends an RRC reconfiguration complete message to the access network device.

[0230] The terminal device establishes SRB2 and DRB based on the RRC reconfiguration message; then, it sends an RRC reconfiguration completion message to the access network device to indicate that the reconfiguration is complete.

[0231] There are many reasons why a terminal device may transition from an idle state to a connected state, or from a deactivated state to a connected state. These reasons could include the terminal device actively initiating the state transition, the core network paging the terminal device, or the access network device paging the terminal device. For example, when a network device sends a paging message to a terminal device, the terminal device receives the paging message, triggers a state transition based on the message, and sends its context information to the network device.

[0232] In one possible scenario, if the access network device pages the terminal device, the terminal device does not need to send the context information stored in the terminal device to the access network device; if the core network pages the terminal device, the terminal device sends the context information stored in the terminal device to the access network device.

[0233] In one possible implementation, prior to steps 501, 601, and 701 described above, the following process is further included: The core network element sends second indication information to the access network device, the second indication information being used to request activation of the terminal device; correspondingly, the access network device receives the second indication information from the core network element. Based on the second indication information, the access network device sends a paging message to the terminal device; correspondingly, the terminal device receives the paging message from the access network device; the paging message includes third indication information, the third indication information being used to instruct the core network element to paging the terminal device. Based on the third indication information, the terminal device sends its stored context information to the access network device.

[0234] In this application, the agreement may specify that the terminal device sends context information stored in the terminal device to the network device; or the network device may instruct the terminal device to send the context information stored in the terminal device to the network device.

[0235] For example, the deactivation state can be divided into two states: a terminal device in the first deactivation state does not need to send the terminal device's context information to the network device, while a terminal device in the second deactivation state sends the terminal device's context information to the network device.

[0236] For example, the idle state can be divided into two sub-states. Terminal devices in the first idle state do not need to send their context information to the network device, while terminal devices in the second idle state send their context information to the network device.

[0237] For example, if the (LEO)NTN RRC inactive state is supported and involves the (LEO)NTN RRC inactive state, the terminal device sends the context information stored by the terminal device to the network device by default.

[0238] For example, if the (LEO)NTN RRC idle state is supported and is involved, the terminal device sends the context information stored by the terminal device to the network device by default.

[0239] In one possible implementation, the network device sends a fourth indication message to the terminal device, the fourth indication message being used to indicate any of the following: When the terminal device releases the RRC connection, enters the deactivated state, or enters the idle state, the terminal device stores the context information; When the terminal device releases the RRC connection, enters the deactivated state, or enters the idle state, the terminal device does not delete the context information already stored by the terminal device. When the terminal device performs RRC connection restoration or RRC connection establishment, it sends the context information stored by the terminal device to the network device. The terminal device enters either the first idle state (the network device stores the context information of the terminal device) or the second idle state (the terminal device stores the context information of the terminal device). The terminal device enters either a first deactivated state (where the network device stores the terminal device's context information) or a second idle state (where the terminal device stores the terminal device's context information).

[0240] In other words, the fourth instruction information is used to instruct the terminal device to store context information, or the network device to store the context information of the terminal device. This application mainly considers the fourth instruction information used to instruct the terminal device to store context information.

[0241] The fourth indication information can be carried in the RRC release message sent by the access network device to the terminal device. For example, the fourth indication information is located in the suspend reconfiguration information of the RRC release message; or, the fourth indication information can be carried in other messages different from the RRC release message.

[0242] By instructing terminal devices whether to send context information to network devices, the system can adapt more flexibly to different scenarios.

[0243] Optionally, before steps 501, 601, and 701 above, the network device or access network device previously serving the terminal device sends a fourth indication message to the terminal device. Based on the fourth indication message, the terminal device sends the context information stored by the terminal device to the network device or access network device in steps 501, 601, and 701.

[0244] Optionally, in the above Figure 5 , Figure 6 or Figure 7 Subsequently, the network equipment or access network equipment currently serving the terminal device (i.e., Figure 5 Network devices in, or Figure 6 ,or Figure 7 The access network device in the network sends an RRC release message and a fourth indication message to the terminal device, or the RRC release message includes the fourth indication message; when the terminal device enters the deactivation state or enters the idle state, it stores the context information based on the fourth indication message, or does not delete the context information already stored by the terminal device, and can send the context information stored by the terminal device to the corresponding network device when it is converted to the connected state next time.

[0245] In one embodiment of this application, the terminal device can send indication information to the network device, which indicates whether the terminal device has stored context information or not. If the terminal device has stored context information, it can send the context information to the network device, and the network device receives and saves the stored context information. If the terminal device has not stored context information, the network device can send the context information to the terminal device, and the terminal device receives and saves the context information. This embodiment can be applied to scenarios including, but not limited to, those described above. Figure 5 , Figure 6 and Figure 7 The scene.

[0246] Figure 8A flowchart of a communication method is presented, illustrating the transmission method of context information of terminal devices during access network device handover. Figure 8 The method is illustrated using access network devices (source access network device and target access network device) and terminal devices as the execution entities in this interaction illustration, but this application does not limit the execution entities in the interaction illustration. For example, the method executed by the access network device in this application can also be implemented by modules (such as circuits, chips or chip systems, etc.) in the access network device, or by logical nodes, logical modules or software that can implement all or part of the functions of the access network device; the method executed by the terminal device in this application can also be implemented by the communication module in the terminal device, or by the circuit or chip (such as a modem chip (also known as a baseband chip), or a SoC chip containing a modem core, or a system-in-package (SIP) chip) in the terminal device responsible for communication functions.

[0247] Optionally, in step 801: the source access network device sends the fifth indication information to the terminal device, and the terminal device receives the fifth indication information accordingly.

[0248] The fifth instruction information is used to instruct the terminal device to send the context information stored in the terminal device to the target access network device.

[0249] For example, the source access network device sends an RRC reconfiguration message to the terminal device (see reference). Figure 4 (406 in the original text) The RRC reconfiguration message includes the fifth indication information; or, the source access network device sends a cell handover command to the terminal device (see reference 406). Figure 4 In step 410), the cell handover command includes the fifth indication information; or, the fifth indication information is carried in any message sent by the source access network device to the terminal device during access network device handover or cell handover.

[0250] In step 801, the source access network device instructs the terminal device to send the context information stored in the terminal device to the target access network device; or, the protocol may stipulate that the terminal device sends the context information stored in the terminal device to the target access network device without the source access network device instructing the terminal device, in which case step 801 can be omitted.

[0251] Step 802: The terminal device sends the context information stored in the terminal device to the target access network device. Correspondingly, the target access network device receives the context information stored in the terminal device from the terminal device. The context information is used by the terminal device to switch to the target access network device.

[0252] If step 801 exists, the terminal device can send the context information stored by the terminal device to the target access network device based on the fifth indication information.

[0253] For example, after the terminal device completes the LTM handover (see reference) Figure 4 In step 412), the context information stored by the terminal device is carried in the RRC reconfiguration completion message, or the context information stored by the terminal device is carried based on the MAC CE during the LTM handover completion process.

[0254] Optionally, the fifth indication information is further used to indicate the time at which the terminal device sends the context information to the target access network device (for ease of description, this time is referred to as the second time); or, the fifth indication information is specifically used to indicate that the terminal device sends the context information to the target access network device before the second time. Based on the fifth indication information, the terminal device sends the context information stored by the terminal device to the target access network device before the second time; of course, it is not excluded that the terminal device sends the context information stored by the terminal device to the target access network device after the second time.

[0255] The second time is related to the satellite handover time. The source access network device can predict when the satellite handover will occur. Based on the satellite handover time, the source access network device can determine the second time. For example, the second time should not be later than the satellite handover time to avoid handover failure.

[0256] The second time can be indicated by an absolute time, such as by a time slot index or a radio frame index, in which case the fifth indication information includes the time slot index or the radio frame index. Alternatively, the second time can also be indicated by a start time and a duration value, in which case the fifth indication information includes the duration value. The start time is, for example, the time when the terminal device receives the fifth indication information, and the duration value represents the time between the terminal device receiving the fifth indication information and the second time. The second time is the time when the terminal device receives the fifth indication information plus this duration value. The start time can also be the time when the terminal device receives other signaling, such as the time when it receives RRC reconfiguration information or a cell handover command from the source access network device.

[0257] In this method, the terminal device sends its stored context information to the target access network device, eliminating the need for the source access network device to send its stored context information to the target access network device. Compared to... Figure 4 This can save step 403, and further, steps 404 and 405 can also be saved.

[0258] Step 803: The source access network device releases the context information of the terminal device.

[0259] For example, after the source access network device sends a cell handover command to the terminal device, it releases the context information of the terminal device.

[0260] For example, at the first moment, the source access network device releases the context information of the terminal device.

[0261] The first moment is related to the satellite handover time. The source access network device can predict when the satellite handover will occur. The source access network device can determine the first moment based on the satellite handover time. For example, the first moment is no later than the satellite handover time.

[0262] For example, the second time point is no later than the first time point.

[0263] The first moment can be an absolute time, such as the first time slot or the first radio frame. The first moment can also be determined by a start time and a duration value. The start time can be the moment when the source access network device sends the fifth indication information, RRC reconfiguration information, or cell handover command to the terminal device. The source access network device can start a timer or timer at the start time. When the timer or timer expires or reaches the set duration value, the source access network device automatically releases the stored context information of the terminal device, without requiring the target access network device to instruct the source access network device to release the UE context. Figure 4 In contrast, step 418 can be omitted, saving signaling overhead and reducing handover latency.

[0264] In addition, when the bearer link between the source access network device and the target access network device is not ideal (such as large bearer link latency, limited bandwidth, instability, or even no bearer link), the terminal device can inform the target access network device of the context information of the terminal device, which can improve the success rate of handover.

[0265] During access network device handover, the source access network device sends the uplink and downlink sequence numbers of the data packets (PDCP sequence numbers) of the terminal device in the serving cell to the target access network device to ensure continuous data transmission. This method can still be used in this application. In another possible implementation, the terminal device can send to the target access network device: the sequence number of the data most recently received by the terminal device from the source access network device, and / or the sequence number of the data most recently sent by the terminal device to the source access network device; for example, the data sequence number, the PDCP sequence number, or the PDCPPDU sequence number. Accordingly, the target access network device receives the sequence number and sends data to the terminal device based on the sequence number.

[0266] For example, during the LTM handover process (see reference) Figure 4 Step 412) The serial number mentioned above is carried either on the MAC CE or in the RRC reconfiguration completion message.

[0267] In this way, there is no need for the source access network device to send the data sequence number to the target access network device, and Figure 4In comparison, step 411 can be omitted, saving signaling overhead.

[0268] In terrestrial networks, the core network cannot predict when a terminal device will switch access network devices or which access network device it will switch to. When the access network device served by a terminal device switches, the path from the core network to the access network device also needs to be switched. Therefore, after the access network device switches, the new access network device informs the core network of the switching path (e.g., Figure 4 Steps 415 to 417 in the text.

[0269] In scenarios where access network equipment is deployed on satellites, the core network can predict when a terminal device will undergo satellite handover and which satellite will be used after the handover. Regardless of the number of handovers, core network elements can locate the satellite serving the terminal device based on its location and establish a new path from the core network to the serving satellite to enable communication with the terminal device. No new access network equipment needs to inform the core network of the handover path. Figure 4 In comparison, steps 415, 416, and 417 can be omitted, saving signaling overhead between the access network equipment and the core network.

[0270] Based on the preceding text Figure 8 The introduction, Figure 9 A flowchart illustrating a communication method is presented.

[0271] Step 901: The terminal device sends L3 measurement reports to the source access network device.

[0272] Step 901 can be referred to step 401, and will not be described in detail here.

[0273] Step 902: LTM decision.

[0274] Step 902 can be referred to step 402, and will not be described in detail here.

[0275] Step 903: The source access network device sends an RRC reconfiguration message to the terminal device.

[0276] The RRC reconfiguration message carries the RRC configuration information of the target cell. The source access network device can obtain the RRC configuration information of the target cell from the target access network device; or the terminal device has already configured the RRC configuration information of the target cell, and the RRC reconfiguration message can carry an indication to activate the RRC reconfiguration information of the target cell.

[0277] Optionally, the RRC reconfiguration message carries a fifth indication information, which is specifically used to instruct the terminal device (before the second time step) to send the context information to the target access network device.

[0278] Step 904: The terminal device sends an RRC reconfiguration complete message to the source access network device.

[0279] For example, the UE saves the RRC configuration information of the target cell.

[0280] Step 905: The terminal device performs L1 measurement and periodically / event-triggeredly reports the L1 measurement results (also known as L1 measurement report).

[0281] Optionally, the UE may perform downlink synchronization (step 906a) and uplink synchronization (step 906b) with the target cell in advance.

[0282] Step 907: The source access network device determines to perform LTM handover based on the L1 measurement results of the terminal device.

[0283] Step 908: The source access network device sends an LTM cell switch command to the terminal device.

[0284] Optionally, the cell handover command carries a fifth indication information, which is specifically used to instruct the terminal device (before the second time step) to send context information to the target access network device.

[0285] Step 909: The terminal device switches to the target access network device based on the LTM cell handover command, and the LTM handover is completed.

[0286] Step 910: After the terminal device successfully switches over, it sends an RRC reconfiguration complete message to the target access network device to indicate that the switchover was successful.

[0287] The RRC reconfiguration completion message includes the context information stored by the terminal device, the sequence number of the data most recently received by the terminal device from the source access network device, and / or the sequence number of the data most recently sent by the terminal device to the source access network device.

[0288] The previous example showed that the terminal device sends the context information stored by the terminal device to the access network device. Optionally, the effective area of ​​the context information of the terminal device is set. When it is not in the effective area, the terminal device updates the context information.

[0289] For example, an access network device sends a paging message or a broadcast message to a terminal device that is in an active or idle state. Correspondingly, the terminal device in the active or idle state receives the paging message or broadcast message. The paging message or broadcast message is used to instruct the terminal device to transition from an idle or deactivated state to a connected state. If the terminal device is not located in the first area, update the context information stored in the terminal device; if the terminal device is located in the first area, there is no need to update the context information stored in the terminal device.

[0290] The first region is used to indicate the effective area of ​​the context information stored by the terminal device. By configuring the effective area of ​​the context information, unnecessary context updates can be avoided, and signaling overhead can be further reduced.

[0291] For example, the first region is determined based on a reference position and a distance threshold; for example, if the distance between the location of the terminal device and the reference position is less than or equal to the distance threshold, then the terminal device is located within the first region; otherwise, the terminal device is not located within the first region.

[0292] For example, the first region is determined based on a list of tracking area codes (TACs); for example, if the terminal device is located in the tracking area corresponding to the TAC list, then the terminal device is located in the first region; otherwise, the terminal is not located in the first region.

[0293] For example, the first region is determined based on a list of RAN-based notification areas (RNAs); for example, if the terminal device is located in the region corresponding to the RNA list, then the terminal device is located in the first region; otherwise, the terminal is not located in the first region.

[0294] In one possible implementation, the paging message includes the identifier of the target cell; the terminal device can transfer the context information by sending context information to the target cell (or the access network device where the target cell is located) based on the identifier of the target cell (if it has been updated, then send the updated information).

[0295] In one possible implementation, the paging message includes a sixth indication information, which is used to instruct the re-authentication of the context information of the terminal device; based on the sixth indication information, the terminal device establishes a re-authentication connection with the core network, which is used by the core network to authenticate and / or update the context information of the terminal device.

[0296] It is understood that, in order to achieve the functions in the above embodiments, the terminal device and access network device include hardware structures and / or software modules corresponding to each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware, software, or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0297] Figure 10 and Figure 11 The diagram illustrates the possible structures of communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of the terminal devices and access network devices in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments.

[0298] like Figure 10 As shown, the communication device 1000 may include modules or units for implementing the methods described in the embodiments above. In one possible design, the communication device 1000 includes a processing unit 1010 and a transceiver unit 1020. Optionally, the communication device 1000 may further include a storage unit 1030 for storing device program code and / or data.

[0299] The communication device 1000 can be a network-side device in the above embodiments, such as an access network device, or a communication module in the access network device, or a circuit, chip, or chip system in the access network device responsible for communication functions.

[0300] The transceiver unit 1020 can perform the receiving and transmitting actions performed by the access network device in the above method embodiments. The processing unit 1010 can perform other actions besides the transmitting and receiving actions performed by the access network device in the above method embodiments.

[0301] For example, the transceiver unit 1020 is used to: receive context information stored in the terminal device from the terminal device, and send the context information stored in the terminal device, I-RNTI, or indication information for activating the context information of the terminal device to the core network element.

[0302] For example, the processing unit 1010 is used to: generate a first message.

[0303] The communication device 1000 can be the terminal side in the above embodiments, such as a terminal device, or a communication module in a terminal device, or a circuit or chip in a terminal device that is responsible for communication functions (such as a modem chip (also known as a baseband chip), or a SoC chip containing a modem core, or a system-in-package (SIP) chip).

[0304] The transceiver unit 1020 can perform the receiving and sending actions performed by the terminal device in the above method embodiments. The processing unit 1010 can perform other actions besides the sending and receiving actions performed by the terminal device in the above method embodiments.

[0305] For example, the transceiver unit 1020 is used to: send context information stored by the terminal device to the access network device.

[0306] For example, the processing unit 1010 is used to: switch from a first state to a second state.

[0307] For a more detailed description of the processing unit 1010 and the transceiver unit 1020, please refer to [link / reference needed]. Figures 5 to 9 The relevant descriptions in the method embodiments shown are directly obtained and will not be repeated here.

[0308] It is understood that the division of units in the above-described device is merely a logical functional division. One function can correspond to one functional unit, or two or more functions can be integrated into one functional unit. In actual implementation, all or some units can be integrated onto a single physical entity, or distributed across different physical entities. Furthermore, the aforementioned functional units can be implemented in hardware, software, or a combination of both. Whether a function is executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for specific applications, but such implementations should not be considered beyond the scope of this application.

[0309] In one example, the functional unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, such as: one or more application-specific integrated circuits (ASICs), or one or more central processing units (CPUs), one or more microcontroller units (MCUs), one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms.

[0310] In one example, storage unit 1030 may include random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, and / or registers, etc. Processing unit 1010 may be implemented by a processor, and transceiver unit 1020 may be implemented by a transceiver.

[0311] like Figure 11 As shown, the communication device 1100 includes at least one processor 1110 and interface circuitry 1120. The processor 1110 and interface circuitry 1120 are coupled to each other. It is understood that the interface circuitry 1120 can be a transceiver or an input / output interface. Optionally, the communication device 1100 may also include a memory 1130 for storing instructions executed by the processor 1110, or storing input data required for the processor 1110 to execute instructions, or storing data generated after the processor 1110 executes instructions. Sometimes, the interface circuitry 1120 can also be understood as part of the processor 1110, in which case the communication device 1100 includes the processor 1110.

[0312] When the communication device 1100 is used to implement the above-mentioned network side and terminal side methods, the processor 1110 is used to implement the functions of the above-mentioned processing unit 1010, the interface circuit 1120 is used to implement the functions of the above-mentioned transceiver unit 1020, and the memory 1130 is used to implement the functions of the above-mentioned storage unit 1030.

[0313] When the aforementioned communication device is a chip applied to a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiments. The terminal device chip receives information from a network device, which can be understood as the information being first received by other modules (such as an RF module or antenna) in the terminal device, and then sent to the terminal device chip by these modules. The terminal device chip sends information to a network device, which can be understood as the information being first sent to other modules (such as an RF module or antenna) in the terminal device, and then sent to the network device by these modules.

[0314] When the aforementioned communication device is a chip used in a network device, the network device chip implements the functions of the network device in the above method embodiments. The network device chip receives information from the terminal device, which can be understood as the information being first received by other modules (such as radio frequency modules or antennas) in the network device, and then sent to the network device chip by these modules. The network device chip sends information to the terminal device, which can be understood as the information being sent down to other modules (such as radio frequency modules or antennas) in the network device, and then sent to the terminal device by these modules. Here, the network device module can be the baseband chip of the network device, or a DU (Digital Unit) or other modules. The DU here can be a DU under the Open Radio Access Network (O-RAN) architecture.

[0315] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be network devices or terminal devices, or modules within network devices or terminal devices. The sending and receiving of information can be between network devices and terminal devices, between two network devices (e.g., CU and DU), or between different modules within a single device (e.g., a terminal device chip and other modules within the terminal device, or a network device chip and other modules within the network device).

[0316] It is understood that the processor in the embodiments of this application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor.

[0317] This application also provides a computer-readable storage medium storing a computer program that, when executed by a computer, enables the computer to perform the aforementioned communication method. Alternatively, the computer program includes instructions for implementing the aforementioned communication.

[0318] This application also provides a computer program product, including: computer program code, which, when run on a computer, enables the computer to execute the communication method provided above.

[0319] This application also provides a communication system, which includes: a network device and a terminal device that perform the above-described communication method; or, a source access network device and a terminal device that perform the above-described communication method.

[0320] The method steps in the embodiments of this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, compact disc read-only memory (CD-ROM), or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a base station or terminal. Of course, the processor and storage medium can also exist as discrete components in the base station or terminal.

[0321] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a first control plane network element, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0322] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0323] In this application embodiment, the number of nouns, unless otherwise specified, refers to "singular nouns or plural nouns," that is, "one or more." "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A or B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. For example, A / B means: A or B. Expressions such as "at least one of the following" or "one or more of them" refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c, or one or more of a, b, or c, means: a, b, c, a and b, a and c, b and c, or a and b and c. Each of a, b, and c can be single or multiple.

[0324] The ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority, or importance of the multiple objects. Furthermore, such names do not indicate differences in the content, sending / receiving end, sending order, size, application scenario, priority, or importance of the two pieces of information. Additionally, the numbering of steps in the various embodiments described in this application is only to distinguish different steps and is not used to limit the order of steps.

Claims

1. A communication method, characterized in that, Chips used in or within network devices, including: The terminal device receives context information stored in the terminal device; the terminal device is in a first state, which is a deactivated state, an idle state, or a connected state. Based on the context information, a first message is sent to the terminal device, the first message being used to instruct the terminal device to transition from the first state to the second state; the second state is a deactivated state, an idle state, or a connected state; the first state and the second state are different.

2. The method as described in claim 1, characterized in that, The network device is an access network device, the first state is a deactivated state, and the second state is a connected state; The receiving of context information stored by the terminal device from the terminal device includes: Receive a Radio Resource Control (RRC) Recovery Request message from the terminal device, the RRC Recovery Request message including context information stored by the terminal device; The first message is an RRC recovery message.

3. The method as described in claim 2, characterized in that, The RRC recovery request message also includes the deactivated wireless network temporary identifier (I-RNTI) of the terminal device, which is associated with the location of the terminal device; The method further includes: Based on the I-RNTI, a first indication message is sent to the core network element, the first indication message being used to indicate the activation of the I-RNTI.

4. The method as described in claim 1, characterized in that, The network device is an access network device, the first state is an idle state, and the second state is a connected state; The receiving of context information stored by the terminal device from the terminal device includes: Receive a Radio Resource Control (RRC) Establishment Request message from the terminal device, wherein the RRC Establishment Request message includes context information stored by the terminal device; The first message is an RRC establishment message.

5. The method as described in claim 4, characterized in that, The method further includes: The context information is sent to the core network element, and the context information is used to establish a connection between the core network element and the access network device.

6. The method according to any one of claims 1-5, characterized in that, The network device is an access network device. Before receiving the context information stored by the terminal device from the terminal device, the method further includes: Receive a second indication information from a core network element, the second indication information being used to request activation of the terminal device; A paging message is sent to the terminal device, the paging message including third indication information, the third indication information being used to instruct the core network element to paging the terminal device.

7. The method according to any one of claims 1-6, characterized in that, The method further includes: Send a fourth indication message to the terminal device, the fourth indication message being used to indicate any of the following: When the terminal device releases the RRC connection, enters a deactivated state, or enters an idle state, the terminal device stores the context information; or, When the terminal device performs RRC connection restoration or RRC connection establishment, it sends the context information to the network device.

8. The method as described in claim 7, characterized in that, The network device is an access network device, and the step of sending the fourth indication information to the terminal device includes: An RRC release message is sent to the terminal device, the RRC release message including the fourth indication information.

9. The method according to any one of claims 1-8, characterized in that, After receiving the status information stored in the terminal device from the terminal device, the method further includes: Save the context information of the terminal device.

10. The method according to any one of claims 1-9, characterized in that, The context information includes at least one of the following: The terminal device's identification information, the terminal device's session identification information, interface identification, tunnel identification, the terminal device's location information, quality of service information, billing information, security information, or the terminal device's capability information.

11. A communication method, characterized in that, Chips used in or in terminal devices include: In the first state, the context information stored by the terminal device is sent to the network device. The context information stored by the terminal device is used for the terminal device to transition from the first state to the second state. Receive a first message from the network device, the first message being used to instruct the terminal device to transition from the first state to the second state; The process transitions from the first state to the second state. The first state is either a deactivated state, an idle state, or a connected state; the second state is either a deactivated state, an idle state, or a connected state; the first state and the second state are different.

12. The method as described in claim 11, characterized in that, The first state is the deactivated state, the second state is the connected state, and the network device is an access network device; Sending the context information stored by the terminal device to the network device includes: Send a Radio Resource Control (RRC) Recovery Request message to the network device, the RRC Recovery Request message including context information stored by the terminal device; The first message is an RRC recovery message.

13. The method as described in claim 12, characterized in that, The RRC recovery request message also includes the deactivated wireless network temporary identifier (I-RNTI) of the terminal device, which is associated with the location of the terminal device.

14. The method as described in claim 11, characterized in that, The first state is an idle state, the second state is a connected state, and the network device is an access network device; Sending the context information stored by the terminal device to the network device includes: Send a Radio Resource Control (RRC) Establishment Request message to the network device, wherein the RRC Establishment Request message includes context information stored by the terminal device; The first message is an RRC establishment message.

15. The method according to any one of claims 11-14, characterized in that, The method further includes: Receive a paging message from the network device, the paging message including third indication information, the third indication information being used to instruct the core network element to paging the terminal device; Sending the context information stored by the terminal device to the network device includes: Based on the third instruction information, the context information stored by the terminal device is sent to the network device.

16. The method according to any one of claims 11-15, characterized in that, The method further includes: Receive a fourth indication message from the network device, the fourth indication message being used to indicate any of the following: When the terminal device releases the RRC connection, enters a deactivated state, or enters an idle state, the terminal device stores the context information; or, When the terminal device performs RRC connection restoration or RRC connection establishment, it sends the context information to the network device.

17. The method as described in claim 16, characterized in that, The network device is an access network device, and receiving the fourth indication information from the network device includes: Receive an RRC release message from the network device, the RRC release message including the fourth indication information.

18. The method according to any one of claims 11-17, characterized in that, The method further includes: If the connection with the network device is released, the context information of the terminal device is stored.

19. The method according to any one of claims 11-18, characterized in that, The context information includes at least one of the following: The terminal device's identification information, the terminal device's session identification information, interface identification, tunnel identification, the terminal device's location information, quality of service information, billing information, security information, or the terminal device's capability information.

20. A communication method, characterized in that, Chips used in or within source access network devices include: Send a fifth instruction message to the terminal device, the fifth instruction message being used to instruct the terminal device to send the context information stored in the terminal device to the target access network device; Release the context information of the terminal device.

21. The method as described in claim 20, characterized in that, The fifth indication information is also used to indicate the time when the terminal device sends the context information to the target access network device.

22. The method as described in claim 20 or 21, characterized in that, Sending the fifth instruction information to the terminal device includes: Send an RRC reconfiguration message to the terminal device, the RRC reconfiguration message including the fifth indication information; or... A cell handover command is sent to the terminal device, and the cell handover command includes the fifth indication information.

23. A communication method, characterized in that, Chips used in or in terminal devices include: The terminal device receives a fifth indication message from the source access network device, the fifth indication message being used to instruct the terminal device to send the context information stored in the terminal device to the target access network device; Based on the fifth indication information, the context information stored by the terminal device is sent to the target access network device, and the context information is used to switch to the target access network device.

24. The method as described in claim 23, characterized in that, The fifth indication information is also used to indicate the time when the terminal device sends the context information to the target access network device.

25. The method as described in claim 24, characterized in that, Sending the context information of the terminal device to the target access network device includes: Before the stated time, the context information of the terminal device is sent to the target access network device.

26. The method according to any one of claims 23-25, characterized in that, The method further includes: Send the sequence number of the packet data aggregation protocol-protocol data unit most recently received by the terminal device from the source access network device to the target access network device.

27. A communication method, characterized in that, Chips used in or in terminal devices include: In the first state, a paging message is received, which instructs the terminal device to transition from the first state to the connected state; the first state is an idle state or a deactivated state. If the terminal device is not located in the first area, the context information stored by the terminal device is updated, whereby the first area is used to indicate the effective area of ​​the context information stored by the terminal device.

28. The method as described in claim 27, characterized in that, The paging message includes the identifier of the target cell; The method further includes: Based on the identifier of the target cell, the context information is sent to the target cell.

29. The method as described in claim 27 or 28, characterized in that, The paging message includes the sixth indication information, which is used to instruct the re-authentication of the context information of the terminal device. The method further includes: Based on the sixth indication information, a re-authentication connection is established between the terminal device and the core network. The re-authentication connection is used by the core network to authenticate and / or update the context information of the terminal device.

30. A communication device, characterized in that, Including the processor; The processor is configured to execute a computer program or instructions, which, when executed, are configured to implement the method as described in any one of claims 1-29.

31. The communication device as claimed in claim 30, characterized in that, Also includes: Memory; the memory stores the computer program or instructions.

32. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions, which, when executed by a communication device, implement the method as described in any one of claims 1-29.

33. A computer program product, characterized in that, The computer program product includes: computer instructions that, when executed on a computer, cause the method as described in any one of claims 1-29 to be implemented.

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