Communication method, apparatus, and computer-readable storage medium

Abstract

The application provides a communication method, device and computer readable storage medium, relates to subsequent switching technology in the field of communication, and can avoid that a network device transmits invalid data packets to a terminal device, thereby effectively improving transmission efficiency. The method comprises the following steps: before the terminal device is switched to a candidate network device, the candidate network device receives at least one first data packet sent by a source network device; then the source network device or a target network device continues to send a first message to the candidate network device, and the first message is used for determining that the terminal device performs switching; accordingly, the candidate network device discards the received at least one first data packet based on the first message.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method, apparatus and computer-readable storage medium. Background Technology

[0002] Mobile communication systems support continuous layer (L1 / L2) triggered mobility (LTM) handovers. This means that after completing an LTM handover, the source network device does not send a "handover cancellation" notification message to other candidate network devices. Therefore, before the first LTM handover, if network device #1 (the network device connected to the terminal device) forwards data from the core network to candidate network devices (e.g., candidate network devices #2 and #3), the candidate network devices may store this received data for use when the terminal device hands over to them. For example, when the terminal device performs its first LTM handover and switches from network device #1 to candidate network device #2, network device #2 can send the data forwarded by network device #1 back to the terminal device.

[0003] However, during subsequent LTM handovers after the first LTM handover, the terminal device may continue to switch from network device #2 to network device #3. If network device #3 continues to send data forwarded by network device #1 to the terminal device, a transmission redundancy problem will occur. Summary of the Invention

[0004] This application provides a communication method, apparatus, and computer-readable storage medium to avoid network devices transmitting invalid data packets to terminal devices and improve transmission efficiency.

[0005] In a first aspect, this application provides a communication method that can be applied to the network side, such as an access network device, a module (e.g., a circuit, chip, or chip system) within the access network device, or a logical node, logical module, or software capable of implementing all or part of the functions of the access network device. The method is described below using a first network device as an example.

[0006] For example, the method includes: receiving at least one first data packet from a second network device; receiving a first message from a second network device, a third network device, or a fourth network device, the first message being used to determine that a terminal device is performing a handover; and discarding at least one first data packet based on the first message.

[0007] In this context, at least one first data packet is a downlink data packet to be transmitted to the terminal device. Alternatively, at least one first data packet is a downlink data packet that the second network device obtains from the core network and needs to be transmitted to the terminal device, but has not yet been transmitted to the terminal device.

[0008] The second network device is the source network device for the nth handover performed by the terminal device, the third network device is the target network device for the nth handover performed by the terminal device, and the first network device is the candidate network device for the nth handover performed by the terminal device, where n is a positive integer. In other words, the at least one first data packet is a data packet sent from the source network device to the candidate network device when the terminal device performs the nth handover. Alternatively, the at least one first data packet is sent from the second network device to the first network device before the terminal device switches to the first network device. Or, the at least one first data packet is sent from the second network device to the terminal device by performing an advance data forwarding process.

[0009] Optionally, the handover performed by the aforementioned terminal device includes: the terminal device is about to perform a handover, the terminal device is performing a handover, or the terminal device has already completed the handover.

[0010] In this context, "the terminal device is about to perform a handover" can mean that the first network device decides to instruct the terminal device to perform a handover. "The terminal device is performing a handover" can mean that the first network device has sent a handover command to the terminal device but has not yet received a handover success message. "The terminal device has performed a handover" can mean that the terminal device has successfully completed the handover or has received a handover success message.

[0011] Based on this technical solution, the second, third, or fourth network device sends a first message to the first network device to determine that the terminal device is performing a handover. This allows the first network device to discard at least one first data packet sent by the second network device before the terminal device switches to it, upon receiving the first message. Since the first network device is a candidate network device for the nth handover, the terminal device may have already received this part of the downlink data packet after performing the nth handover. Therefore, the method provided in this application, where the first network device discards at least one first data packet based on the first message to determine that the terminal device is performing a handover, can prevent the terminal device from continuing to send the at least one first data packet when performing the (n+1)th handover from the third network device to the first network device. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0012] In conjunction with the first aspect, in a first possible implementation, the first message is a first message from the third network device, which is used to request and establish an association between the terminal device and the third network device.

[0013] It should be understood that this first message is sent after the terminal device successfully switches to the third network device.

[0014] For example, the first message may be an LTM configuration update request message from a third network device.

[0015] Optionally, the first message may include identification information assigned by the first network device to the terminal device. In this way, the first network device can identify which terminal device the association requested by the third network device pertains to.

[0016] Optionally, the first message is used to determine that the terminal device is performing a handover, including: determining that the terminal device is switching to the third network device based on the first message used to establish an association between the terminal device and the third network device. Therefore, it can be said that the first message is used to instruct the terminal device to send a message indicating a handover or a change of serving cell.

[0017] In conjunction with the first aspect, in the second possible implementation, the first message is a first message from the second network device.

[0018] In one possible design, the first message is used to indicate the target cell of the terminal device, or to indicate the target network device of the terminal device.

[0019] It is understandable that when the terminal device performs the nth handover, the target cell is a cell managed by the third network device, and the target network device is the third network device.

[0020] In a second possible design, the first message is an early status transfer message, which indicates the sequence numbers of data packets that the first network device should clear / drop. In this case, the first message is used to determine that the terminal device is performing a handover, including: the first network device, based on the early status transfer message, discarding all data packets with sequence numbers less than the specified sequence number.

[0021] In the first and second possible designs, the first message can be sent by the second network device after deciding to perform a handover, or it can be sent after the terminal device successfully hands over to the third network device. That is, the condition for triggering the first message can be one of the following: the second network device decides to perform a handover, or the second network determines that the terminal device has successfully handed over to the third network device.

[0022] In conjunction with the first aspect, in a third possible implementation, in a dual-connectivity scenario, the first network device, the second network device, and the third network device are all auxiliary network devices. In this case, the first message can be a first message from the fourth network device, used to indicate the target cell of the terminal device, or used to indicate the target network device of the terminal device.

[0023] The fourth network device is the primary network device that serves the terminal device through a dual-link connection with the secondary network device. The first message is sent after the terminal device successfully switches to the third network device. For example, the third network device may send the first message to the first network device after receiving an RRC reconfiguration completion message from the terminal device.

[0024] For a description of the target cell and target network equipment, please refer to the previous description; it will not be repeated here.

[0025] As an example, when the first message is used to indicate the target cell of the terminal device, the first message is used to determine that the terminal device is performing a handover, including: determining that the target cell is not the cell of the first network device based on the first message indicating the target cell of the terminal device, and then determining that the terminal device has performed a handover.

[0026] As another example, when the first message is used to indicate the target network device of the terminal device, the first message is used to determine that the terminal device is performing a handover, including: determining that the target network device is not the first network device based on the first message indicating the target network device of the terminal device, and then determining that the terminal device has performed a handover.

[0027] Secondly, this application provides a communication method that can be applied to the network side, such as an access network device, a module (e.g., a circuit, chip, or chip system) within the access network device, or a logical node, logical module, or software capable of implementing all or part of the functions of the access network device. The method is described below using a second network device as an example.

[0028] For example, the method further includes: sending at least one first data packet to a third network device and a first network device, the at least one first data packet being a downlink data packet to be transmitted to a terminal device; and sending a first message to the first network device, the first message being used to determine that the terminal device is performing a handover.

[0029] The descriptions of at least one first data packet, the first network device, the second network device, and the third network device can be found in the descriptions in the first aspect above, and will not be repeated here. The description of the first message can be found in the description of the first possible design above, and will not be repeated here.

[0030] Based on this technical solution, the second network device sends a first message to the first network device to determine that the terminal device is performing a handover. This allows the first network device to discard at least one first data packet received by the terminal device before it switched to its network device after receiving the first message. Thus, if the terminal device performs a handover for the n+1th time after the nth handover, switching from the third network device to the first network device, the first network device will not send the at least one first data packet to the terminal device again. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0031] Optionally, before sending the first message to the first network device, the method further includes: determining to switch the terminal device to the third network device. That is, the first message is sent by the first network device after deciding to perform the switch.

[0032] Optionally, before sending the first message to the first network device, the method further includes: receiving a handover success message from the third network device, the handover success message indicating that the terminal device has successfully switched to the third network device. That is, the first message is sent after the terminal device has successfully switched to the third network device.

[0033] Thirdly, this application provides a communication method that can be applied to the network side, such as access network equipment, modules (e.g., circuits, chips, or chip systems) within the access network equipment, or logical nodes, logical modules, or software capable of implementing all or part of the functions of the access network equipment. The method is described below using a second network device as an example.

[0034] For example, the method includes: sending at least one first data packet to a third network device and a first network device, the at least one first data packet being a downlink data packet to be transmitted to the terminal device; and, upon deciding to perform a handover or receiving a handover success message from the third network device, sending an early state transition message to the first network device, the early state transition message indicating that one or more first data packets belonging to the at least one first data packet.

[0035] The descriptions of at least one first data packet, the first network device, the second network device, and the third network device can be found in the descriptions in the first aspect above, and will not be repeated here. The description of the first message can be found in the description of the second possible design above, and will not be repeated here.

[0036] Based on this technical solution, the second network device sends an early state transition message to the first network device to determine if the terminal device is performing a handover. This allows the first network device to discard at least one first data packet received by the terminal device before it switched to this network device after receiving the early state transition message. Thus, if the terminal device performs the (n+1)th handover after the nth handover, switching from the third network device to the first network device, the first network device will not send that at least one first data packet to the terminal device again. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0037] Fourthly, this application provides a communication method that can be applied to the network side, such as an access network device, a module (e.g., a circuit, chip, or chip system) within the access network device, or a logical node, logical module, or software capable of implementing all or part of the functions of the access network device. The method is described below using a fourth network device as an example.

[0038] For example, the method includes: determining that a terminal device has switched to a third network device; and sending a first message to a first network device, the first message being used to determine that the terminal device has performed a switch.

[0039] The descriptions of at least one first data packet, the first network device, the second network device, and the third network device are as described in the first aspect above and will not be repeated here. However, in the fourth aspect, the first network device, the second network device, and the third network device are all auxiliary network devices, and the fourth network device serves the terminal device through a dual-connection method with the auxiliary network devices. Therefore, the fourth network device can also be called the main network device.

[0040] For a description of the first message, please refer to the description in the third possible implementation method above, which will not be repeated here.

[0041] Based on this technical solution, the fourth network device sends a first message to the first network device to determine that the terminal device is performing a handover. This allows the first network device to discard at least one first data packet sent by the second network device before the terminal device switches to it, upon receiving the first message. Since the first network device is a candidate network device for the nth handover, the terminal device may have already received this part of the downlink data packet after performing the nth handover. Therefore, the method provided in this application, where the first network device discards at least one first data packet based on the first message to determine that the terminal device is performing a handover, can prevent the terminal device from continuing to send the at least one first data packet when performing the (n+1)th handover from the third network device to the first network device. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0042] Fifthly, this application provides a communication device, including modules or units for implementing the methods of any of the above aspects and any possible implementations of any of the above aspects. It should be understood that each module or unit can implement its corresponding function by executing a computer program.

[0043] Sixthly, this application provides a communication device including a processor, the processor being configured to perform the methods described in any of the foregoing aspects and any possible implementations of any of the foregoing aspects.

[0044] The apparatus may further include a memory for storing instructions and data. The memory is coupled to the processor, which, when executing the instructions stored in the memory, can implement the methods described in the foregoing aspects.

[0045] The device may also include a communication interface for communicating with other devices. For example, the communication interface may be a transceiver, circuit, bus, module or other type of communication interface.

[0046] In a seventh aspect, this application provides a chip system including at least one processor for supporting the implementation of the functions involved in any of the above aspects and any possible implementations of any of the above aspects, such as receiving or processing data and / or information involved in the above methods.

[0047] In one possible design, the chip system also includes a memory for storing program instructions and data, which may be located within or outside the processor.

[0048] The chip system can consist of chips or include chips and other discrete components.

[0049] Eighthly, this application provides a computer-readable storage medium storing a computer program that, when run on a computer, causes the computer to implement the methods in any of the foregoing aspects and any possible implementations of any of the foregoing aspects.

[0050] Ninthly, this application provides a computer program product comprising: a computer program (also referred to as code or instructions) that, when run, causes a computer to perform the methods of any of the above aspects and any possible implementations of any of the above aspects.

[0051] It should be understood that the fifth to ninth aspects of this application correspond to the technical solutions of the first to fourth aspects of this application, and the beneficial effects obtained by each aspect and the corresponding feasible implementation are similar, and will not be repeated here. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the architecture of the communication system provided in the embodiments of this application;

[0053] Figure 2 This is another schematic diagram of the communication system provided in the embodiments of this application;

[0054] Figure 3 This is a schematic diagram of a separate architecture provided in an embodiment of this application;

[0055] Figure 4 This is a schematic flowchart of the early data forwarding process in LTM;

[0056] Figure 5 This is a schematic flowchart illustrating the advance data forwarding process in conditional handover (CHO).

[0057] Figures 6 to 8 This is a schematic flowchart of the communication method provided in the embodiments of this application;

[0058] Figure 9 This is a schematic block diagram of the device provided in the embodiments of this application;

[0059] Figure 10 This is another schematic block diagram of the device provided in the embodiments of this application. Detailed Implementation

[0060] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0061] To facilitate understanding of the embodiments of this application, the following points are explained first:

[0062] First, in the embodiments of this application, the use of prefixes such as "first" and "second" is merely for the purpose of distinguishing and describing different things belonging to the same name category, and does not constrain the order, size, or quantity of things. For example, "first network device" and "second network device" are simply different network devices, and do not limit the number of network devices or their priority relationship.

[0063] Second, in the embodiments of this application, "send" and "receive" indicate the direction of signal transmission. For example, "sending LTM candidate configuration information to the terminal device" can be understood as the destination of the information being the terminal device, which may include sending directly via the air interface or sending indirectly via the air interface by other units or modules. "Receiving an LTM switching command from a first network device" can be understood as the source of the switching command being the first network device, which may include receiving directly from the first network device via the air interface or receiving indirectly from the first network device via the air interface by other units or modules. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface.

[0064] In other words, sending and receiving can occur between network devices, such as between a terminal device and a first network device; or they can occur within a device, such as between components, modules, chips, software modules, or hardware modules within the device via a bus, wiring, or interface.

[0065] It is understandable that information may undergo necessary processing, such as encoding and modulation, before being sent from the source to the destination. Similarly, the destination, upon receiving information from the source, can also perform corresponding processing, such as decoding and demodulation, to interpret the valid information from the source. Similar expressions in this application can be understood in a similar way and will not be elaborated further.

[0066] Third, in the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates an "or" relationship between the preceding and following related objects, but it does not exclude the possibility of indicating an "and" relationship. The specific meaning can be understood in conjunction with the context. "At least one of the following" or similar expressions 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 can represent: a, b, c; a and b; a and c; b and c; or a and b and c. Here, a, b, and c can be single or multiple.

[0067] Fourth, in the embodiments of this application, "instruction" can include direct instruction and indirect instruction, as well as explicit instruction and implicit instruction. The information indicated by a certain piece of information (as described below, the instruction information) is called the information to be instructed. In the specific implementation process, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index. It can also indirectly indicate the information to be instructed by indicating other information, where there is a correlation between the other information and the information to be instructed; or it can only indicate a part of the information to be instructed, while the other parts of the information to be indicated are known or pre-agreed upon. For example, the instruction of specific information can be achieved by using a pre-agreed (e.g., protocol predefined) arrangement of various pieces of information, thereby reducing the instruction overhead to a certain extent. This application does not limit the specific method of instruction.

[0068] It is understandable that, for the sender of the instruction information, the instruction information can be used to indicate the information to be indicated, and for the receiver of the instruction information, the instruction information can be used to determine the information to be indicated.

[0069] Fifth, in the embodiments of this application, descriptions such as "when," "under the circumstances," "if," and "if" all refer to the fact that the device (e.g., network device or terminal device) will make corresponding processing under certain objective circumstances. They are not time limits, nor do they require the device (e.g., network device or terminal device) to make a judgment action when implementing it, nor do they mean that there are other limitations.

[0070] Sixth, the predefined terms in this application can be understood as: definition, pre-defined, storage, pre-storage, pre-negotiation, pre-configuration, solidification, or pre-firing.

[0071] Seventh, the term "storage" in this application can refer to storage in one or more memory devices. These memory devices can be separate installations or integrated into an encoder, decoder, processor, or communication device. Alternatively, some memory devices can be separately installed, while others can be integrated into the decoder, processor, or communication device. The type of memory can be any form of storage medium, and this application does not limit this.

[0072] The technical solutions of this application can be applied to various communication systems, such as Global System for Mobile Communications (GSMA), Long Term Evolution (LTE) systems, Universal Mobile Telecommunications System (UMTS), 4th Generation (4G) mobile communication systems, 4.5th Generation (4.5G) mobile communication systems, 5th Generation (5G) mobile communication systems, satellite communication systems, and future communication networks. The technical solutions of this application can also be applied to Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access (CDMA) systems, and Wireless Local Area Networks (WLANs).

[0073] Figure 1 This is a schematic diagram of the architecture of the communication system provided in an embodiment of this application. Figure 1 As shown, the communication system diagram includes terminal device 110, network device 120, network device 130, and network device 140. Network device 120 covers area 1, network device 130 covers area 2, and network device 140 covers area 3. If terminal device 110 is located in area 1, it can communicate with network device 120 uplink and downlink; if it is located in area 2, it can communicate with network device 130 uplink and downlink; and if it is located in area 3, it can communicate with network device 140 uplink and downlink.

[0074] Understandable. Figure 1 This is just an illustration; the communication system may also include more network devices or more terminal devices, or it may include other devices such as wireless relay devices and wireless backhaul devices.

[0075] Figure 2 This is another schematic diagram of the communication system provided in the embodiments of this application. For example... Figure 2 As shown, the communication system 200 includes a terminal device 210, a network device 220, and a network device 230. When the terminal device 210 supports dual connectivity (DC) functionality, the terminal device 210 can connect to both the network device 220 and the network device 230 simultaneously, with both network devices providing services to the terminal device 210 to improve its transmission rate and reliability.

[0076] In network devices 220 and 230, the network device to which the terminal device connects first can be called the main network device, and the network device to which it connects later can be called the auxiliary network device (in this application, network device 220 is referred to as the auxiliary network device, and network device 230 as the main network device). That is to say, the auxiliary network device is added to the terminal device by the main network device. For a description of the main and auxiliary network devices, please refer to existing technologies; further details are omitted here.

[0077] The network device in this application may be, for example, an access network device. An access network device is a network-side device with wireless transceiver capabilities, such as a device in a radio access network (RAN) that provides wireless communication capabilities for terminal devices, and may be called an RAN device or an RAN node.

[0078] As an example, access network equipment includes, but is not limited to, base stations (base transceiver stations, BTS, Node B, evolved Node B (eNodeB) / eNB, or next-generation Node B (gNodeB) / gNB), transmission reception points (TRPs), home evolved NodeBs (or home Node Bs, HNBs), base stations evolved under the 3rd Generation Partnership Project (3GPP), access points (APs) in Wi-Fi systems, mobile switching centers, wireless relay nodes, and wireless backhaul nodes. Base stations can be macro base stations, micro base stations, pico base stations, small cells, relay stations, donor nodes, or indoor stations. Multiple base stations can support networks using the same access technology or networks using different access technologies. A base station can contain one or more co-located or non-co-located transmit / receive points. Another example is that access network devices can also be radio controllers in cloud radio access network (CRAN) scenarios, nodes in open radio access network (O-RAN or ORAN) scenarios, etc. Yet another example is that access network devices can also be servers, wearable devices, vehicles, or in-vehicle equipment. For instance, in V2X technology, access network devices can be roadside units (RSUs).

[0079] In one possible scenario, a RAN node can also be a device that functions as a base station in a device-to-device (D2D) communication system, a vehicle-to-everything (V2X) communication system, a machine-to-machine (M2M) communication system, or an internet-to-things (IoT) communication system. A RAN node can also be a RAN node in a non-terrestrial network (NTN), meaning that a RAN node can be deployed on a high-altitude platform or on a satellite.

[0080] In another possible scenario, multiple RAN nodes collaborate to assist terminal devices in achieving wireless access, with different RAN nodes each implementing a portion of the base station's functions. For example, RAN nodes can be central units (CUs), distributed units (DUs), CU-control plane (CPs), CU-user plane (UPs), or radio units (RUs), etc. CUs and DUs can be set up separately or included in the same network element, such as 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). Optionally, a central unit can also be called a control unit.

[0081] In other words, access network devices can adopt a CU-DU separation architecture, which can also be called a distributed deployment architecture. Figure 3 This is a schematic diagram of a separate architecture provided in an embodiment of this application. For example... Figure 3 As shown, the access network device can logically include one CU and one or more DUs. Each DU can be connected to the CU through an F1 interface, and information exchange between different DUs can be completed based on forwarding by the CU. The CU and DU can be physically set together or physically separated, and this application does not limit this.

[0082] like Figure 3As shown, the CU and DU nodes separate the protocol layers of the access network equipment. Some protocol layer functions are centrally controlled by the CU, while the remaining partial or complete protocol layer functions are distributed in the DU, which is centrally controlled by the CU. In one protocol stack partitioning method, the CU deploys the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, and Service Data Adaptation Protocol (SDAP) layer; the DU deploys the Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical Layer (PHY) layer. Thus, the CU has the processing capabilities for RRC, PDCP, and SDAP. The DU has the processing capabilities for RLC, MAC, and PHY. It is understood that the above functional partitioning is only an example and does not constitute a limitation on the CU and DU.

[0083] 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 an open CU (O-CU), DU can also be called an open DU (O-DU), CU-CP can also be called an open CU-CP (O-CU-CP), CU-UP can also be called an open CU-UP (O-CU-UP), and RU can also be called an open RU (O-RU). Any of the units among CU (or CU-CP, CU-UP), DU, and RU can be implemented through software modules, hardware modules, or a combination of software and hardware modules. That is, the wireless access network device in this application can be a virtualized device, for example, implemented through general-purpose hardware and instantiated virtualization functions, or dedicated hardware and instantiated virtualization functions. The general-purpose hardware can be a server, such as a cloud server.

[0084] In this embodiment, the apparatus for implementing the functions of a network device can be a network device itself, or an apparatus capable of supporting the network device in implementing those functions, such as a chip system, hardware circuit, software module, or a hardware circuit plus a software module. This apparatus can be installed in or used in conjunction with the network device. In this embodiment, the example of a network device is used only to illustrate the apparatus for implementing the functions of the network device, and does not constitute a limitation on the solutions described in this embodiment.

[0085] The terminal equipment in this application is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from RAN nodes. The terminal equipment may also be referred to as a terminal device, terminal, user equipment (UE), mobile station, mobile terminal, access terminal, subscriber unit, user station, user terminal, wireless communication equipment, user agent, or user equipment, etc.

[0086] Terminal devices are used to connect people, things, and machines, and can be widely used in various scenarios, including but not limited to: cellular communication, enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), massive machine-type communications (mMTC), device-to-device (D2D), vehicle-to-everything (V2X), machine-type communication (MTC), Internet of Things (IoT), ISAC, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, remote medical care, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, drones, robots, or indoor commercial scenarios (such as mobile phone screen mirroring, file sharing, and mobile phone to VR glasses video transmission), etc.

[0087] When terminal equipment is used in V2X, it can also be called V2X equipment. Examples include smart cars, digital cars, unmanned cars, driverless cars, pilotless cars, autonomous cars, pure electric vehicles (EVs), hybrid electric vehicles (HEVs), range-extended electric vehicles (REEVs), plug-in hybrid electric vehicles (PHEVs), new energy vehicles, and roadside units (RSUs). Terminal equipment can also be devices used in D2D communication, such as electricity meters and water meters.

[0088] Currently, examples of terminal devices include: mobile phones, tablets, computers with wireless transceiver capabilities (such as laptops and PDAs), mobile internet devices (MIDs), virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving vehicles, drones, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to wireless modems, in-vehicle devices, wearable devices, terminal devices in 5G networks, or future public land mobile communication networks. Terminal equipment in a mobile network (PLMN), etc.

[0089] Furthermore, in this embodiment, the terminal device can also be a terminal device in an IoT system. IoT is an important component of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, thereby realizing an intelligent network of human-machine interconnection and object-to-object interconnection.

[0090] In addition, terminal devices may also include sensors such as smart printers, train detectors, and gas stations. Their main functions include collecting data (for some terminal devices), receiving control information and downlink data from network devices, and sending electromagnetic waves to transmit uplink data to network devices.

[0091] The terminal device in this application can be a virtualized device, for example, implemented through general-purpose hardware and instantiated virtualization functions, or dedicated hardware and instantiated virtualization functions. The general-purpose hardware can be a server, such as a cloud server.

[0092] In this application embodiment, the communication device used to implement the terminal device function can be the terminal device itself, or it can be a device capable of supporting the terminal device in implementing the function, such as a chip system, hardware circuit, software module, or hardware circuit plus software module. This device can be installed in the terminal device or used in conjunction with the terminal device. In the technical solutions provided in this application embodiment, the terminal device is used as an example to describe the technical solutions provided in this application embodiment.

[0093] exist Figure 1 and Figure 2 In the mobile communication system shown, as the location of the terminal device moves, the communication link between the terminal device and the network device may change. In this case, the terminal device may need to perform cell handover or network device handover. For example, Figure 1 Terminal device 110 switches from network device 120 to network device 130, and then switches again to network device 140. For example, Figure 2 Terminal device 210 switches from network device 230 to other network devices.

[0094] To ensure that when the communication link between the terminal device and the network device changes, the protocol defines a variety of switching methods (e.g., LTM, CHO) to guarantee the user's communication experience.

[0095] 1) LTM is a handover technology introduced in 5G communication systems. LTM can also be called lower-layer triggered mobility or bottom-layer triggered handover. L1 refers to the physical layer, and L2 refers to the MAC / RLC / PDCP / SDAP layers. L1 / L2 triggered mobility handover means that handover-related operations are mainly performed in L1 and L2 (e.g., the MAC layer). For example, the terminal device sends the measurement results to the base station via physical layer control signaling (e.g., carried on the physical uplink control channel, PUCCH). The base station's physical layer reads the L1 measurement results and makes a handover decision based on the measurement results, then sends it to the terminal device via L2 signaling (e.g., the media access control element, MAC CE). That is, the main technical point of LTM is: the source network device obtains the configuration information of the candidate cell from the candidate network device and sends it to the terminal device. Then, the source network device makes a handover decision based on the measurement results reported by the terminal device and sends an LTM handover command to the terminal device.

[0096] LTM supports subsequent handover technologies. For example, if the source network device is gNB1 (the source cell is cell 1 managed by gNB1), and the candidate network devices are gNB2 and gNB3, where cell 2 provided by gNB2 is one candidate cell, and cell 3 provided by gNB3 is another candidate cell, the first LTM handover is from cell 1 to cell 2. After the first LTM handover, the terminal device can retain the configuration of the candidate cells for subsequent handovers, such as the second LTM handover, where the terminal device switches from cell 2 to cell 3.

[0097] 2) CHO is a handover technology triggered by a terminal device. The main process is as follows: the network device configures candidate cells and corresponding handover conditions (also known as events) for the candidate cells to the terminal device; when the terminal device evaluates that the handover conditions are met, the terminal device triggers the handover process and accesses the corresponding candidate cell. An example of a handover condition is: when the reference signal strength of candidate cell Cell2 is higher than the reference signal strength of the source cell (or serving cell) Cell1 by a first threshold value.

[0098] Furthermore, in handover scenarios, to ensure the data obtained from the core network is forwarded to the terminal device, the source network device forwards this data to the target network device, which then sends it to the terminal device, thus guaranteeing service continuity. Two data forwarding methods are illustrated below:

[0099] In method one, the source network device sends the data to the target network device after the terminal device switches from the source network device to the target network device (i.e., after the source network device determines that the terminal device has successfully switched to the target network device). This data forwarding method can be called data forwarding, "normal" data forwarding, or "late" data forwarding, etc.

[0100] Method 2 involves the source network device sending this portion of data to the target network device and other candidate network devices before the terminal device switches from the source network device to the target network device (i.e., before the source network device sends a handover command to the terminal device). This data forwarding method can be called early data forwarding, etc.

[0101] The following describes the advance data forwarding process in the LTM and CHO switching process.

[0102] Figure 4 This is a schematic flowchart illustrating the early data forwarding process in LTM. For example... Figure 4 As shown, the process may include the following steps:

[0103] S401, Network Device 1 (i.e., the source network device) sends LTM configuration information to the terminal device, which includes the configuration information of candidate cells. Correspondingly, the terminal device receives the LTM configuration information from the source network device.

[0104] Optionally, before step 1, the source network device may request the configuration information of the candidate cell from the candidate network devices. There may be one or more candidate network devices; this example uses network device 2 and network device 3 as candidate network devices.

[0105] S402, network device 1 forwards downlink data to network device 2 and network device 3. Correspondingly, network device 2 and network device 3 receive the downlink data. That is, the source network device performs the process of advance data forwarding.

[0106] S403, Network device 1 sends an LTM cell handover command (hereinafter referred to as LTM handover command) to the terminal device, which instructs the terminal device to hand over to cell 2. Correspondingly, the terminal device receives the LTM handover command.

[0107] In this context, cell 2 is the target cell, and the candidate network device for managing cell 2 is network device 2. This network device 2 can also be referred to as the target network device.

[0108] For example, the source network device can make a handover decision based on the measurement results reported by the terminal device. That is, before step 2, the terminal device sends the measurement results to the source network device. Correspondingly, the source network device receives the measurement results and performs the handover decision.

[0109] S404, according to the LTM handover command, the terminal device activates the corresponding cell 2 configuration information and executes the handover process to access network device 2. (That is, an LTM cell handover process is performed between the terminal device and network device 2.)

[0110] It should be understood that network device 2 is the target network device for this handover and also the source network device for subsequent handovers.

[0111] It should also be understood that after the terminal device connects to network device 2, network device 2 can send the downlink data received via step 2 to the terminal device.

[0112] For example, during a subsequent handover process, if the terminal device switches from network device 2 to another candidate network device (e.g., network device 3), network device 3 may send downlink data from step 2 to the terminal device during downlink data transmission. Since the terminal device has already received the downlink data from step 2 during its communication with network device 2, if network device 3 continues to send this part of the downlink data to the terminal device, it will result in the transmission of many redundant data packets to the terminal device, reducing communication efficiency.

[0113] Figure 5 This is a schematic flowchart illustrating the advance data forwarding process in a CHO (Content-Oriented Hashtag). CHOs use advance data forwarding technology to allow candidate network devices to receive downlink service data in advance, thus enabling downlink service data transmission to begin when a terminal connects to the candidate network device. For example... Figure 5 As shown, the process may include the following steps:

[0114] S501, Network device 1 (i.e., the source network device) sends CHO configuration information to the terminal device. The CHO configuration information includes the configuration information of the candidate cell and the handover conditions / events corresponding to the candidate cell.

[0115] Optionally, before step 1, the source network device requests the configuration information of the candidate cells from the candidate network devices. There can be one or more candidate network devices; this example uses network device 2 and network device 3 as candidate network devices.

[0116] S502, Network device 1 forwards downlink data to both Network device 1 and Network device 2. That is, Network device 1 performs the process of advance data forwarding.

[0117] S503, the terminal equipment performs CHO event assessment. That is, it assesses whether the handover conditions / events corresponding to the candidate cell are met.

[0118] S504: After the handover conditions / events corresponding to candidate cell Cell2 (managed by network device 2) are met, the terminal device applies the configuration of Cell2 and performs the handover. (That is, the handover process is performed between the terminal device and network device 2.)

[0119] S505, after the terminal device successfully connects to network device 2 (i.e., the target network device), network device 2 sends a handover success notification message to network device 1.

[0120] S506, network device 1 sends a handover cancellation message to other candidate network devices (i.e., network device 3). Network device 3 can release the configuration information prepared for the terminal device or clear the downlink data received in step 2.

[0121] Based on this, it is easy to conclude that to avoid the terminal device receiving duplicate downlink data, a handover cancellation communication message can be sent to other candidate network devices (e.g., network device 3) to instruct network device 3 to release the data received in step 2. However, this method is not suitable for LTM technology that supports subsequent handovers. This is because in LTM technology that supports subsequent handovers, other candidate network devices that have not become the target network device can still serve as candidate network devices for subsequent handovers of the terminal device. If, after completing an LTM handover, the source network device sends a "handover cancellation" notification message to other candidate network devices, it may cause the other candidate network devices to release the configuration information prepared for that terminal device, resulting in the inability to support subsequent LTM handovers. Therefore, candidate network devices may continue to store invalid data packets, leading to the transmission of invalid data packets to the terminal device and reducing transmission efficiency.

[0122] In view of this, embodiments of this application provide a communication method, apparatus, and computer-readable storage medium. In this method, for a candidate network device in the nth handover, after receiving a first message from the source or target network device in the nth (n is a positive integer) handover, used to determine that the terminal device is performing a handover, the downlink data packets obtained through the advance data forwarding process are discarded. This effectively avoids the terminal device receiving duplicate downlink data when switching to the candidate network device in the nth candidate handover, thereby effectively improving transmission efficiency.

[0123] The communication method and apparatus provided in the embodiments of this application are described in detail below with reference to the accompanying drawings. It should be understood that the communication method provided in the embodiments of this application can be applied to mobility technologies that support subsequent handover, including mobility technologies that support subsequent handover triggered by network devices and mobility technologies that support subsequent handover triggered by terminal devices, for example... Figure 4 The LTM technology shown is a handover triggered by a network device. It can also be applied to mobility technologies that support subsequent handovers triggered by the terminal device, i.e., CHOs that support subsequent handovers, such as Conditional LTMs that support subsequent handovers. It should be noted that in CHO procedures or Conditional LTM procedures that support subsequent handovers, the source network device does not need to send a handover command to the terminal device, but it does need to configure the handover event for the terminal device. Furthermore, after the terminal device hands over to the target network device, it does not send a handover cancellation message to the candidate network device.

[0124] Figure 6 This is a schematic flowchart of a communication method provided in an embodiment of this application. This communication method 600 can be applied to... Figure 1 The communication system shown is applied in a non-dual-connectivity scenario. Figure 6 The method 600 shown is described from the perspective of interaction between multiple network devices, but this application does not limit the subject that performs the method. For example, each of the multiple network devices can be replaced by a chip, chip system, or processor that supports the implementation of the method by that network device, or it can be a logic module or software that can implement all or part of the functions of that network device.

[0125] like Figure 6 As shown, method 600 may include steps S601 to S608. The steps in method 600 are described in detail below.

[0126] S601, the second network device sends at least one first data packet to the first network device, the at least one first data packet being a downlink data packet to be transmitted to the terminal device. Correspondingly, the first network device receives at least one first data packet from the second network device.

[0127] In this context, the first network device is a candidate network device for the terminal device to perform the nth handover, and the second network device is the source network device for the terminal device to perform the nth handover, where n is a positive integer. That is, the aforementioned at least one first data packet is sent by the second network device to the first network device before the terminal device switches to the first network device. Alternatively, the at least one first data packet is a downlink data packet sent by the second network device during the advance data forwarding process.

[0128] In this application, the downlink data packet to be transmitted to the terminal device refers to the downlink data packet that the second network device obtains from the core network and needs to be transmitted to the terminal device, but has not yet been transmitted to the terminal device.

[0129] Optionally, prior to S601, the method 600 may further include: S602, whereby the terminal device obtains LTM configuration information or CHO configuration information from the serving cell.

[0130] S603, the second network device or the third network device sends a first message to the first network device. Correspondingly, the first network device receives the first message, which is used to determine that the terminal device is performing a handover.

[0131] The third network device is the target network device for the terminal device to perform the nth handover.

[0132] For example, determining that the terminal device is about to perform a handover may include: determining that the terminal device is about to perform a handover, determining that the terminal device is performing a handover, or determining that the terminal device has completed the handover.

[0133] The phrase "determines that the terminal device will perform a handover" can be replaced with "determines that the first network device decides to order the terminal device to perform a handover".

[0134] Determining that the terminal device is performing a handover can be replaced with: determining that the first network device sent a handover command to the terminal device but did not receive a handover success message; or determining that the terminal device received the handover command, but the first network device did not receive a handover success message.

[0135] "It is confirmed that the terminal device has completed the handover" can be replaced with "It is confirmed that the terminal device has performed the handover or has received a handover success message".

[0136] S605, the first network device discards at least one first data packet based on the first message.

[0137] The word "discard" in this application can also be replaced with: clear, delete, etc.

[0138] Specifically, the first network device discarding at least one first data packet based on the first message may include: the first network device determining, based on the first message, that the terminal device is performing a handover; and then discarding at least one first data packet.

[0139] It is understandable that the specific content indicated by the first message from different network devices may differ. The following section, combining two possible implementations, describes how the first network device determines the handover process for the terminal device based on the first messages from different network devices.

[0140] In one possible implementation, the first message is a message from a third network device, which is used to request and establish an association between the terminal device and the third network device.

[0141] It is understandable that after the third network device and the first network device establish an association for the terminal device, the third network device and the second network device can transmit relevant information about the terminal device.

[0142] Optionally, the first message may include identification information assigned by the first network device to the terminal device. For example, the first message may include the UE Xn application protocol ID (UE XnAP ID) previously assigned to the terminal device by the third network device. Since the first network device may assign different identifiers to different terminal devices, by carrying the identification information assigned by the first network device to the terminal device, the first network device can identify which terminal device the requested association pertains to.

[0143] It should be noted that this first message is sent only after the terminal device switches to the third network device. Therefore, upon receiving this first message, the first network device can determine that the terminal device has completed the handover and switched to the third network device. Based on this, the first network device can determine that at least one previously received first data packet has expired and can therefore discard that at least one first data packet.

[0144] It is understood that the first network device may receive downlink data packets corresponding to multiple different terminal devices before receiving the first message. Therefore, when discarding previously received downlink data packets, the downlink data packet corresponding to that terminal device can be discarded based on the terminal device identification information carried in the first message. For example, the first network device can discard at least one first data packet corresponding to that terminal device based on the terminal device identification information (e.g., UE XnAP ID) carried in the first message.

[0145] In the first possible implementation, the first message can also be understood as indicating that a handover or change of serving cell has occurred on the terminal device.

[0146] For example, the first message could be an LTM configuration update request message.

[0147] In a second possible implementation, the first message is a first message from the second network device. This first message can be used to indicate the target cell of the terminal device (i.e., the cell managed by the third network device), or the first message can also be used to indicate the target network device of the terminal device (i.e., the second network device).

[0148] Optionally, the first message may be sent by the second network device after deciding to perform the handover. That is, before S603 above, the method 600 may also include: S604, the second network device determines to hand over the terminal device to the third network device.

[0149] Alternatively, the first message can also be sent by the second network device after sending a handover command to the terminal device. That is, before S602 above, method 600 may further include: S606, the second network device sends a handover command to the terminal device, the handover command including the identification information of the target cell. Correspondingly, the terminal device receives the handover command from the second network device. Wherein, the target cell is the third network device.

[0150] Alternatively, the first message can be sent after the terminal device successfully switches to the third network device. That is, before S602 above, method 600 may further include: S608, the third network device sends a handover success message to the second network device, the handover success message indicating that the terminal device has successfully switched to the third network device. Correspondingly, the second network device receives the handover success message from the terminal device.

[0151] As an example, the first message can be used to indicate the target cell of the terminal device. Accordingly, after receiving the first message, the first network device can determine whether the target cell indicated by the first message is a cell managed by the first network device; if the target cell is not a cell of the first network device, it is determined that the terminal device has performed a handover.

[0152] As another example, the first message can also be used to indicate the target network device (i.e., the third network device) of the terminal device. Accordingly, after receiving the first message, the first network device can determine whether the target network device is the first network device based on the target network device indicated by the first message; if the target network device is not the first network device, it is determined that the terminal device has performed a handover.

[0153] Optionally, the first message can also be used to indicate the source network device of the terminal device or other information.

[0154] For example, the first message can reuse the format of an existing cell handover notification message, so the first message can also be called a cell handover notification message. In this case, the difference between the first message and the existing cell handover notification message lies in the destination. The destination of the existing cell handover notification message is a third network device, but the destination of the first message is the first network device. Furthermore, the timing of the second network device sending the existing cell handover notification message and the first message can be different. The existing cell handover notification message is sent after deciding to perform the handover, while the first message in this application can be sent by the second network device after deciding to perform the handover, or by the second network device after sending a handover command to the terminal device, or by the terminal device after successfully handing over to the third network device.

[0155] In this embodiment, the second or third network device sends a first message to the first network device to determine that the terminal device is performing a handover. This allows the first network device to discard at least one first data packet sent by the second network device before the terminal device switches to it, upon receiving the first message. Since the first network device is a candidate network device for the nth handover, the terminal device may have already received this part of the downlink data packets after performing the nth handover. Therefore, the method provided in this embodiment, where the first network device discards at least one first data packet based on the first message to determine that the terminal device is performing a handover, can prevent the terminal device from continuing to send the at least one first data packet when performing the (n+1)th handover from the third network device to the first network device. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0156] For example, in a CU-DU separation architecture, S602 above can be replaced by: any of the following network devices' CUs (denoted as CU2) sending a first message to the CU of the first network device (denoted as CU1): a second network device, a third network device, or a fourth network device. If CU1 did not send at least one received first data packet to DU1 before S602, then S603 above can be replaced by: CU1 discarding the at least one first data packet. If CU1 sent at least one received first data packet to DU1 before S602, then S603 above can be replaced by: CU1 sending an indication message to DU1 to discard previously received data packets; DU1 receiving the indication message and discarding at least one first data packet based on the indication message. Here, DU1 is the DU managed / supported / associated by CU1.

[0157] Figure 7 This is another illustrative flowchart of the communication method provided in the embodiments of this application. It should be understood that... Figure 7 The communication method shown can also be applied to Figure 1 The communication system shown is applied in a non-dual-connectivity scenario. Figure 7 The method 700 shown is described from the perspective of interaction between multiple network devices, but this application does not limit the subject that performs the method. For example, each of the multiple network devices can be replaced by a chip, chip system, or processor that supports the implementation of the method by that network device, or it can be a logic module or software that can implement all or part of the functions of that network device.

[0158] like Figure 7 As shown, method 700 may include steps S701 to S708. The steps in method 700 are described in detail below.

[0159] S701, the second network device sends at least one first data packet to the first network device, the at least one first data packet being a downlink data packet to be transmitted to the terminal device. Correspondingly, the first network device receives at least one first data packet from the second network device.

[0160] For a description of S701, please refer to the description in S601; it will not be repeated here.

[0161] Similarly, prior to S701, the method 700 may also include: S702, whereby the terminal device obtains LTM configuration information or CHO configuration information from the serving cell.

[0162] In step S703, upon deciding to perform a handover or receiving a handover success message from the third network device, the second network device sends an early status transfer message to the first network device. Correspondingly, the first network device receives the early status transfer message from the second network device, which indicates the sequence number (for simplicity, referred to as the first sequence number) of the data packets to be discarded.

[0163] In other words, the second network device needs to trigger this early state transition message after deciding to perform a handover or receiving a handover success message from the third network device.

[0164] That is, before S703, the method 700 may further include at least one of the following steps S704 to S708:

[0165] S704, the second network device decides to perform a handover. Alternatively, the second network device decides to instruct the terminal device to perform a handover. Or, the second network device determines to hand over the terminal device from the second network device to the third network device.

[0166] S706. The second network device sends a handover command to the terminal device, which instructs the terminal device to hand over to the target cell. Correspondingly, the terminal device receives the handover command from the second network device.

[0167] S708, the third network device sends a handover success message to the second network device. This handover success message indicates that the terminal device has successfully handed over to the third network device. Correspondingly, the second network device receives the handover success message from the terminal device.

[0168] S705, the first network device, based on an early state transition message, discards / clears / deletes all or part of the first data packet in at least one first data packet.

[0169] Specifically, based on the early state transition message, the first network device discards all data packets with sequence numbers smaller than the first sequence number corresponding to at least one first data packet.

[0170] As an example, the first sequence number indicated by the early state transition message can be the largest sequence number among the sequence numbers corresponding to at least one first data packet. In this way, the first network device can discard all at least one first data packet based on the first sequence number indicated by the early state transition message.

[0171] As another example, if the first sequence number indicated by the early state transition message is not the largest sequence number among the sequence numbers corresponding to at least one first data packet, then the first network device discards the first data packet corresponding to a sequence number less than or equal to the first sequence number indicated by the early state transition message.

[0172] Regarding the CU-DU separation architecture, the description of S705 can be found in S605, except that the first message is replaced with an early state transition message, and discarding at least one first data packet is replaced with discarding all or part of the first data packets in at least one first data packet. For the sake of brevity, it will not be elaborated further here.

[0173] In this embodiment, when the second network device decides to perform a handover or receives a handover success message from the third network device, it sends an early state transition message to the first network device to confirm that the terminal device is performing a handover. This allows the first network device to discard all or part of the first data packets in at least one first data packet sent by the second network device before the terminal device switches to its network device, after receiving the early state transition message. This effectively prevents the terminal device from continuing to send the at least one first data packet when performing the (n+1)th handover from the third network device to the first network device, which not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0174] Figure 8 This is another illustrative flowchart of the communication method provided in the embodiments of this application. It should be understood that... Figure 8 The communication method shown is applied to Figure 2 The communication system shown is applied in a dual-connectivity scenario. Figure 8 The method 800 shown is described from the perspective of interaction between multiple network devices, but this application does not limit the subject that performs the method. For example, each of the multiple network devices can be replaced by a chip, chip system, or processor that supports the implementation of the method by that network device, or it can be a logic module or software that can implement all or part of the functions of that network device.

[0175] like Figure 8 As shown, the method 800 may include steps S801 to S810. The steps in method 800 are described in detail below.

[0176] S801, the second network device sends at least one first data packet to the first network device, the at least one first data packet being a downlink data packet to be transmitted to the terminal device. Correspondingly, the first network device receives at least one first data packet from the second network device.

[0177] For a description of S801, please refer to the description in S601; it will not be repeated here. However, it should be noted that in a dual-connectivity scenario, both the second network device and the second network device are auxiliary network devices.

[0178] Similarly, prior to S801, the method 800 may also include: S802, whereby the terminal device obtains LTM configuration information or CHO configuration information from the serving cell.

[0179] S803, the fourth network device (i.e., the primary network device) determines that the terminal device has switched to the third network device. This third network device is a secondary network device.

[0180] Specifically, the primary network device can determine that the terminal device has switched to the third network device after receiving the RRC reconfiguration complete message from the terminal device. That is, before S803, method 800 may further include: S804, the terminal device sends an RRC reconfiguration complete message to the primary network device, which indicates that the secondary network device has changed. Correspondingly, the primary network device receives the RRC reconfiguration complete message from the terminal device.

[0181] In other words, the RRC reconfiguration completion message is sent after the terminal device switches to the third network device. Therefore, before S804, the method 800 may also include steps S806 and S808: S806, the second network device sends a handover command to the terminal device, which instructs the terminal device to switch to the target cell; S808, the third network device sends a handover success message to the second network device.

[0182] For a description of the switching command and the switching success message, please refer to the relevant description in Method 700, which will not be repeated here.

[0183] Optionally, after S803, the method 800 may further include: S810, the master network device sends an RRC reconfiguration completion message to the third network device, the RRC reconfiguration completion message being used to indicate that the terminal device has completed the reconfiguration of the third network device.

[0184] In step S805, the master network device sends a first message to the first network device. Correspondingly, the first network device receives this first message, which is used to determine whether the terminal device is performing a handover. In other words, the first network device can determine whether the terminal device is performing a handover based on the received first message.

[0185] The first message can be used to indicate the target cell of the terminal device (i.e., the cell managed by the third network device). Alternatively, the first message can also be used to indicate the target network device of the terminal device (i.e., the third network device).

[0186] S807, the first network device, based on the first message, discards / deletes / clears at least one first data packet.

[0187] For a description of S807, please refer to the description in S605; it will not be repeated here.

[0188] Specifically, the first network device discarding / deleting / clearing at least one first data packet based on the first message may include: the first network device determining, based on the first message, that the terminal device has performed a handover; and then discarding / deleting / clearing at least one first data packet.

[0189] For example, the first message can be used to indicate the target cell of the terminal device (i.e., the cell managed by the third network device). At this time, the first network device can determine whether the target cell is a cell (managed) by the first network device based on the target cell indicated by the first message. If the target cell is not a cell of the first network device, it is determined that the terminal device has performed a handover.

[0190] For example, the first message can also be used to indicate the target network device (i.e., the third network device) of the terminal device. Accordingly, after receiving the first message, the first network device can determine whether the target network device is the first network device based on the target network device indicated by the first message; if the target network device is not the first network device, it is determined that the terminal device has performed a handover.

[0191] In this embodiment, the fourth network device sends a first message to the first network device to determine that the terminal device is performing a handover. This allows the first network device to discard at least one first data packet sent by the second network device before the terminal device switches to it, upon receiving the first message. Since the first network device is a candidate network device for the nth handover, the terminal device may have already received this part of the downlink data packets after performing the nth handover. Therefore, the method provided in this embodiment, where the first network device discards at least one first data packet based on the first message to determine that the terminal device is performing a handover, can prevent the terminal device from continuing to send the at least one first data packet when performing the (n+1)th handover from the third network device to the first network device. This not only improves communication efficiency but also effectively reduces the network device's need for large storage space.

[0192] As an optional implementation, in technologies supporting subsequent handovers, if the terminal device performs the nth handover and successfully switches from the second network device to the third network device, the third network device can also send at least one second data packet to the target network device and candidate network devices (including the first network device) for the terminal device's (n+1)th handover. In this case, S603 can be replaced by the following step: the first network device receives at least one second data packet from the third network device and discards at least one first data packet.

[0193] Wherein, at least one of the second data includes: downlink data that the third network device obtains from the core network and needs to be transmitted to the terminal device, but has not yet been transmitted to the terminal device, and / or one or more first data packets that the third network device has not transmitted to the terminal device.

[0194] As another optional implementation, the first message carries first indication information for instructing the discarding of at least one first data packet. Alternatively, step 1 can be performed before or after S603 (or S805), or S603 (or S805) can be directly replaced with step 1: Step 1, any of the following network devices sends the first indication information to the first network device: a second network device, a third network device, or a fourth network device. In this case, S605 (or S807) can be replaced with: the first network device discards at least one first data packet based on the first indication information.

[0195] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0196] Figure 9 and Figure 10 The diagram illustrates possible apparatuses provided for embodiments of this application. These apparatuses can be used to implement the functions of any of the first to fourth network devices in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments.

[0197] Figure 9 This is a schematic block diagram of the apparatus provided in the embodiments of this application. Figure 9 As shown, the device 900 includes a transceiver module 910 and a processing module 920.

[0198] One possible design is that device 900 is used to achieve the above. Figures 6 to 8 The method embodiment shown illustrates the function of the first network device.

[0199] For example, the transceiver module 910 is configured to: receive at least one first data packet from a second network device, the at least one first data packet being a downlink data packet to be transmitted to a terminal device; and receive a first message, the first message being used to determine that the terminal device is performing a handover; the processing module 920 is configured to: discard the at least one first data packet based on the first message.

[0200] Optionally, the processing module 920 is further configured to: determine, based on the first message requesting the establishment of an association between the terminal device and the third network device, that the terminal device is switched to the third network device, wherein the third network device is the target network device for the terminal device to perform the nth switch.

[0201] Optionally, the processing module 920 is further configured to: determine, based on the first message indicating the target cell of the terminal device, that the target cell is not the cell of the first network device, and thus determine that the terminal device has performed a handover; or, based on the first message indicating the target network device of the terminal device, determine that the target network device is not the first network device, and thus determine that the terminal device has performed a handover.

[0202] For a more detailed description of the transceiver module 910 and the processing module 920 mentioned above, please refer to [link / reference needed]. Figure 6 The relevant descriptions in the illustrated embodiments are directly obtained and will not be repeated here.

[0203] Another possible design is that device 900 is used to achieve the above. Figure 7 The method embodiment shown illustrates the function of the second network device.

[0204] For example, the transceiver module 910 is configured to: send at least one first data packet to a third network device and a first network device, the at least one first data packet being a downlink data packet to be transmitted to a terminal device; and send a first message to the first network device, the first message being used to determine that the terminal device is performing a handover.

[0205] Optionally, the processing module 920 is configured to: determine to switch the terminal device to the third network device.

[0206] Optionally, the transceiver module 910 is further configured to: receive a handover success message from the third network device, the handover success message being used to indicate that the terminal device has successfully switched to the third network device.

[0207] For example, the transceiver module 910 is configured to: send at least one first data packet to a third network device and a first network device, the at least one first data packet being a downlink data packet to be transmitted to the terminal device; and, upon deciding to perform a handover or receiving a handover success message from the third network device, send an early state transition message to the first network device, the early state transition message indicating that one or more first data packets belonging to the at least one first data packet are discarded.

[0208] For a more detailed description of the transceiver module 910 and the processing module 920 mentioned above, please refer to [link / reference needed]. Figure 7 The relevant descriptions in the illustrated embodiments are directly obtained and will not be repeated here.

[0209] Another possible design is that device 900 is used to achieve the above. Figure 8 The method embodiment shown illustrates the function of the fourth network device.

[0210] For example, the processing module 920 is configured to: determine that the terminal device has switched to a third network device. The transceiver module 910 is configured to: send a first message to the first network device, the first message being used to determine that the terminal device has performed a switch.

[0211] For a more detailed description of the transceiver module 910 and the processing module 920 mentioned above, please refer to [link / reference needed]. Figure 8 The relevant descriptions in the illustrated embodiments are directly obtained and will not be repeated here.

[0212] It should be noted that device 900 may include a transmitting module but not a receiving module. Alternatively, device 900 may include a receiving module but not a transmitting module. Specifically, it depends on whether the above-described scheme executed by device 900 includes both transmitting and receiving actions. It is understood that because device 900 has communication capabilities, it can also be called a communication device.

[0213] Figure 10 This is another schematic block diagram of the device provided in the embodiments of this application. For example... Figure 10 As shown, the device 1000 includes one or more processors 1010. The processor 1010 can be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the device (e.g., a first network device, a second network device, a fourth network device, or a chip), execute software programs, and process data from the software programs.

[0214] Optionally, in one design, processor 1010 may include a program (also referred to as code or instructions) that can be executed on processor 1010, causing device 1000 to perform the methods performed by the first network device, second network device, or third network device in the above method embodiments. In yet another possible design, device 1000 includes circuitry (…). Figure 8 (Not shown), the circuit is used to implement the functions of the first network device, the second network device, or the fourth network device in the above method embodiments.

[0215] For example, processor 1010 can be used to execute computer programs or instructions in memory to achieve Figures 6 to 8 The steps performed by the first network device, second network device, or fourth network device in any of the embodiments shown.

[0216] Optionally, the device 1000 may include one or more memories 1020 storing programs (sometimes referred to as code or instructions) that can be run on the processor 1010, causing the device 1000 to perform the methods executed by the first network device, the second network device, or the fourth network device in the above embodiments.

[0217] Optionally, the processor 1010 and / or memory 1020 may also store data. The processor and memory may be configured separately or integrated together.

[0218] Optionally, the device 1000 may further include a communication interface 1030. The processor 1010, sometimes referred to as a processing unit, controls the device (e.g., a first network device, a second network device, or a fourth network device). The communication interface 1030, sometimes referred to as a transceiver unit, transceiver, transceiver circuit, or transceiver, is used to implement the transceiver function of the device.

[0219] Optionally, the device 1000 also includes a communication interface 1030. The processor 1010 and the communication interface 1030 are coupled to each other. It is understood that the communication interface 1030 can be a transceiver or an input / output interface.

[0220] It is understandable that since device 1000 has communication capabilities, it can also be called a communication device.

[0221] When device 1000 is used to achieve Figures 6 to 8 In this method, the processor 1010 performs the functions of the aforementioned processing unit, and the communication interface 1030 performs the functions of the aforementioned transceiver module. Whether the communication interface 1030 is used for sending or receiving depends on whether the device 1000 is used to perform a sending or receiving action in the execution scheme.

[0222] It should be noted that the above method embodiments can be applied to a processor, or implemented by a processor. A processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by software instructions.

[0223] The aforementioned processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0224] The steps of the method disclosed in the embodiments of this application can be directly manifested as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in mature storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0225] The memory in this application embodiment can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0226] The methods provided in the above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, in the form of a computer program product. The computer program product may include one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may 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 may be a magnetic medium (e.g., floppy disk, hard disk, magnetic disk), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0227] This application also provides a computer program product that, when run on a processor, can implement the methods shown in the above method embodiments.

[0228] This application also provides a computer-readable storage medium containing computer instructions that, when executed on a processor, can implement the methods shown in the above-described method embodiments.

[0229] This application also provides a chip, including a processor, for reading instructions stored in a memory. When the processor executes the stored instructions, the chip can implement the method shown in the above method embodiments.

[0230] This application also provides a communication system, comprising one or more of the aforementioned terminal device, and a first network device, a second network device, a third network device, or a fourth network device.

[0231] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented 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 each specific application, but such implementation should not be considered beyond the scope of this application.

[0232] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0233] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0234] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0235] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0236] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0237] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, Applied to a first network device, the method includes: Receive at least one first data packet from a second network device, wherein the at least one first data packet is a downlink data packet to be transmitted to the terminal device; Receive a first message, the first message being used to determine that the terminal device is performing a handover; Based on the first message, discard at least one first data packet; Wherein, the second network device is the source network device for the terminal device to perform the nth handover, and the first network device is the candidate network device for the terminal device to perform the nth handover, where n is a positive integer.

2. The method according to claim 1, characterized in that, The first message is a Mobility LTM Configuration Update Request message triggered by a Layer 1 or Layer 2 third network device, which is the target network device for the terminal device to perform the nth handover.

3. The method according to claim 1 or 2, characterized in that, The first message is used to determine that the terminal device is performing a handover, including: Based on the first message used to request and establish an association between the terminal device and the third network device, it is determined that the terminal device switches to the third network device, where the third network device is the target network device for the terminal device to perform the nth switch.

4. The method according to claim 1, characterized in that, The first message is a first message from the second network device. The first message is sent by the second network device after deciding to perform a handover, or after the terminal device successfully switches to the third network device. The third network device is the target network device for the terminal device to perform the nth handover.

5. The method according to claim 1, characterized in that, Both the first network device and the second network device are auxiliary network devices; The first message is a message from the fourth network device, and the fourth network device and the auxiliary network device serve the terminal device through a dual-link method.

6. The method according to any one of claims 1, 4, and 5, characterized in that, The first message is used to determine that the terminal device is performing a handover, including: Based on the first message indicating the target cell of the terminal device, it is determined that the target cell is not a cell of the first network device, and thus it is determined that the terminal device has performed a handover; or... Based on the first message indicating the target network device of the terminal device, it is determined that the target network device is not the first network device, and thus it is determined that the terminal device has performed a handover.

7. A communication method, characterized in that, Applied to a second network device, the method includes: Send at least one first data packet to a third network device and a first network device, wherein the at least one first data packet is a downlink data packet to be transmitted to a terminal device; Send a first message to the first network device, the first message being used to determine that the terminal device is performing a handover; Wherein, the second network device is the source network device for the terminal device to perform the nth handover, the third network device is the target network device for the terminal device to perform the nth handover, and the first network device is the candidate network device for the terminal device to perform the nth handover, where n is a positive integer.

8. The method according to claim 7, characterized in that, Before sending the first message to the first network device, the method further includes: The terminal device is switched to the third network device.

9. The method according to claim 8, characterized in that, Before sending the first message to the first network device, the method further includes: The terminal device receives a handover success message from the third network device, the handover success message indicating that the terminal device has successfully switched to the third network device.

10. The method according to any one of claims 7 to 9, characterized in that, The first message is used to indicate the target cell of the terminal device, or to indicate the target network device of the terminal device.

11. A communication method, characterized in that, Applied to a second network device, the method includes: Send at least one first data packet to a third network device and a first network device, wherein the at least one first data packet is a downlink data packet to be transmitted to a terminal device; Upon deciding to perform a handover or receiving a handover success message from the third network device, an early state transition message is sent to the first network device. The early state transition message is used to indicate the sequence number of the data packet to be discarded, and the one or more first data packets belong to the at least one first data packet. Wherein, the second network device is the source network device for the terminal device to perform the nth handover, the third network device is the target network device for the terminal device to perform the nth handover, and the first network device is the candidate network device for the terminal device to perform the nth handover, where n is a positive integer.

12. A communication method, characterized in that, Applied to a fourth network device, the method includes: It has been determined that the terminal device has switched to a third network device; Send a first message to the first network device, the first message being used to determine that the terminal device has performed a handover; The third network device is the target network device for the terminal device to perform the nth handover, the first network device is the candidate network device for the terminal device to perform the nth handover, and the fourth network device serves the terminal device through a dual-linkage mechanism with the third network device, where n is a positive integer.

13. The method according to claim 12, characterized in that, The first message is used to indicate the target cell of the terminal device, or to indicate the target network device of the terminal device.

14. A communication device, characterized in that, Includes modules for implementing the method as described in any one of claims 1 to 13.

15. A communication device, characterized in that, It includes at least one processor for causing the communication device to implement the method as described in any one of claims 1 to 13 by executing a computer program and / or by logic circuitry.

16. A computer-readable storage medium storing a computer program thereon, characterized in that, When the computer program is executed by a processor, the method of any one of claims 1 to 13 is performed.

17. A computer program product, characterized in that, Includes a computer program, and when the computer program is run, the method of any one of claims 1 to 13 is performed.

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