Communication methods and communication apparatus

Abstract

Provided in the embodiments of the present application are communication methods and a communication apparatus, which can improve the capability to support low-latency services in HO scenarios. In order to achieve the objective, the present application uses the following technical solution: a source access network device sending first information to a target access network device, the first information being used for indicating discard information of downlink (DL) data transmitted from the source access network device to a terminal device.

Description

Communication methods and communication devices Technical Field

[0001] This application relates to the field of communications, and more specifically, to communication methods and communication devices. Background Technology

[0002] With the rapid development of information technology, extended reality (XR) technology has become a shining star in the current technology field. XR technology, by merging the real and virtual worlds, brings users an unprecedented immersive experience. The emergence of 5G technology has provided strong network support for the widespread application of XR technology. However, the latency and jitter issues of XR pose significant challenges to wireless air interface transmission.

[0003] The emergence of 5G technology has provided strong support for the widespread application of XR technology. 5G networks, characterized by high speed, low latency, and wide connectivity, can meet the high requirements of XR technology for real-time performance, stability, and reliability. Through 5G networks, XR devices can transmit high-definition video, audio, and sensor data in real time, achieving a seamless integration of the real and virtual worlds. However, latency and jitter issues in XR technology pose significant challenges to wireless air interface transmission. Latency refers to the time required from the sending end to the receiving end receiving the data, while jitter refers to the fluctuation of latency. In XR applications, latency and jitter directly affect the user experience. If the latency is too high or the jitter is too severe, users will experience stuttering images, intermittent sound, and even discomfort such as dizziness and nausea.

[0004] For XR technology, achieving millisecond-level latency and stable transmission is crucial. However, during wireless air interface transmission, latency and jitter are difficult to avoid due to factors such as signal attenuation, interference, and multipath effects. Therefore, reducing latency and jitter, especially improving support for low-latency services in handover (HO) scenarios, has become a key challenge for the application of XR technology in 5G. Summary of the Invention

[0005] This application provides a communication method and a communication device that can improve the support for low-latency services in HO scenarios.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] Firstly, a communication method is provided. This method can be executed by a source access network device, or by a component of the source access network device, such as a processor, chip, or chip system, or by a logic module or software capable of implementing all or part of the functions of the source access network device. Taking the method being executed by the source access network device as an example, the method includes: the source access network device sending first information to a target access network device, the first information being used to indicate the discard information of downlink DL data transmitted by the source access network device to the terminal device.

[0008] The communication method provided in this application embodiment involves a source access network device sending first information to a target access network device. This first information indicates whether DL data being transmitted from the source access network device to the terminal device has been discarded. This method improves the effectiveness of data transmission by allowing the source access network device to indicate data discard information to the target access network device, thereby ensuring support for low-latency services.

[0009] Secondly, a communication method is provided. This method can be executed by a target access network device, or by a component of the target access network device, such as its processor, chip, or chip system. It can also be implemented by a logic module or software capable of implementing all or part of the functions of the target access network device. Taking the method being executed by the target access network device as an example, the method includes: the target access network device receiving first information from a source access network device, the first information indicating the discard information of downlink DL data transmitted by the source access network device to the terminal device; and the target access network device sending the first information to the terminal device.

[0010] The communication method provided in this application embodiment involves a target access network device receiving first information from a source access network device and then sending the first information to a terminal device. The first information indicates whether data transmitted from the source access network device to the terminal device has been discarded. By receiving the first information from the source access network device, the target access network device can transmit valid data or data not discarded by the source access network device to the terminal device based on the first information. This improves the effectiveness of data transmission and prevents resource waste caused by transmitting data discarded by the source access network device to the terminal device, thereby ensuring support for low-latency services.

[0011] Thirdly, a communication method is provided. This method can be executed by a source access network device, or by a component of the source access network device, such as a processor, chip, or chip system, or by a logic module or software capable of implementing all or part of the functions of the source access network device. Taking the method being executed by the source access network device as an example, the method includes: the source access network device receiving first information from a terminal device, the first information being used to indicate the discard information of uplink UL data transmitted by the terminal device to the source access network device; and the source access network device sending the first information to a target access network device.

[0012] The communication method provided in this application embodiment involves a terminal device sending data discard information to a source access network device, instructing the terminal device to discard data transmitted to the source access network device. Subsequently, the source access network device can instruct the target access network device to discard the data transmitted by the terminal device to the source access network device, thereby improving the effectiveness of data transmission and ensuring support for low-latency services.

[0013] In one possible implementation, the first information is carried in a new field of the SN STATUS TRANSFER message.

[0014] In one possible implementation, the first information is carried in a new field of the EARLY STATUS TRANSFER message.

[0015] In one possible implementation, the first information includes one or more of the following:

[0016] Loss status information for at least one business data unit, or the sequence number or COUNT value of the first lost data.

[0017] In one possible implementation, the first information includes one or more of the following:

[0018] Data type, PDU type, sequence number or COUNT value of the data discarded by the terminal device, or loss status information of at least one business data unit.

[0019] In one possible implementation, the data discard information indicated by the first information is discard information at the PDU Set granularity.

[0020] In one possible implementation, the first information includes one or more of the following:

[0021] The PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0022] Fourthly, a communication method is provided. This method can be executed by a target access network device, or by a component of the target access network device, such as a processor, chip, or chip system of the target access network device. It can also be implemented by a logic module or software capable of implementing all or part of the functions of the target access network device. Taking the method being executed by the target access network device as an example, the method includes: the target access network device receiving first information from a source access network device, the first information being used to indicate the discard information of uplink UL data transmitted by the terminal device to the source access network device; the target access network device receiving UL data from the terminal device according to the first information.

[0023] The communication method provided in this application embodiment allows the target access network device to receive data loss information from the source access network device, instructing the terminal device to discard data transmitted to the source access network device. This enables the target access network device to avoid waiting for lost data, thereby ensuring support for low-latency services.

[0024] In one possible implementation, the first information is carried in a new field of the SN STATUS TRANSFER message.

[0025] In one possible implementation, the first information is carried in a new field of the EARLY STATUS TRANSFER message.

[0026] In one possible implementation, the first information includes one or more of the following:

[0027] Loss status information for at least one business data unit, or the sequence number or COUNT value of the first lost data.

[0028] In one possible implementation, the data discard information indicated by the first information is discard information at the PDU Set granularity.

[0029] In one possible implementation, the first information includes one or more of the following:

[0030] The PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0031] Fifthly, a communication method is provided. This method can be executed by a terminal device, or by a component of the terminal device, such as a processor, chip, or chip system, or by a logic module or software capable of implementing all or part of the terminal device's functions. Taking the method being executed by a terminal device as an example, the method includes: the terminal device switching from a source access network device to a target access network device; the terminal device sending first information to the target access network device, the first information being used to indicate the discard information of uplink UL data transmitted by the terminal device to the source access network device.

[0032] The communication method provided in this application embodiment allows the terminal device to directly send information about data loss during the transmission of data from the source access network device to the target access network device after the terminal device switches from the source access network device to the target access network device. This saves resources for making instructions and allows the terminal device to transmit valid data to the target access network device, thereby ensuring the support capability for low-latency services.

[0033] In one possible implementation, the first information is transmitted via the Uu interface.

[0034] In one possible implementation, the first information is carried in the Packet Convergence Protocol Interval Sequence Number Status Report (PDCP SN GAP).

[0035] In one possible implementation, before the terminal device sends the first information to the target access network device, the method further includes: the terminal device receiving status feedback information from the target access network device; the terminal device sending the first information to the target access network device includes: the terminal device sending the first information to the target access network device based on the status feedback information.

[0036] Sixthly, a communication method is provided. This method can be executed by a target access network device, or by a component of the target access network device, such as a processor, chip, or chip system of the target access network device, or by a logic module or software capable of implementing all or part of the functions of the target access network device. Taking the method being executed by the target access network device as an example, the method includes: the target access network device receiving first information from a terminal device, the first information indicating discard information of uplink UL data transmitted by the terminal device to the source access network device; and the target access network device receiving UL data from the terminal device according to the first information.

[0037] The communication method provided in this application embodiment allows the target access network device to receive data loss information from the terminal device during the transmission of data from the terminal device to the source access network device. Consequently, the target access network device can, based on the first information, stop waiting for lost data or receive valid data, thus ensuring support for low-latency services.

[0038] In one possible implementation, the first information is transmitted via the Uu interface.

[0039] In one possible implementation, the first information is carried in the Packet Convergence Protocol Interval Sequence Number Status Report (PDCP SN GAP).

[0040] In one possible implementation, before the target access network device receives the first information from the terminal device, the method further includes: the target access network device sending status feedback information to the terminal device.

[0041] In a seventh aspect, a communication apparatus is provided for implementing the various methods described above. The communication apparatus may be a source access network device as described in the first or third aspect, or a device included in the source access network device, such as a chip; or, the communication apparatus may be a target access network device as described in the second, fourth, or sixth aspect, or a device included in the target access network device, such as a chip; or, the communication apparatus may be a terminal device as described in the fifth aspect, or a device included in the terminal device, such as a chip.

[0042] The communication device includes modules, units, or means that implement the above methods. These modules, units, or means can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the above functions.

[0043] In some possible designs, the communication device may include a processing module and a communication module. The communication module may include an output module (or transmitting module) and an input module (or receiving module), respectively used to implement the output (or transmitting) and input (or receiving) functions in any of the above aspects and any possible designs. The processing module can be used to implement the processing functions in any of the above aspects and any possible designs.

[0044] Optionally, the communication device also includes a storage module for storing program instructions and data.

[0045] Eighthly, a communication device is provided, comprising: at least one processor configured to execute computer programs or instructions, or to cause the communication device to perform the method described in any of the preceding aspects via logic circuitry. The communication device may be a source access network device as described in the first or third aspect, or a device included in the source access network device, such as a chip; or, the communication device may be a target access network device as described in the second, fourth, or sixth aspect, or a device included in the target access network device, such as a chip; or, the communication device may be a terminal device as described in the fifth aspect, or a device included in the terminal device, such as a chip.

[0046] In some possible designs, the communication device also includes a memory for storing configuration files of computer instructions and / or logic circuits. Optionally, the memory is integrated with the processor, or the memory is independent of the processor.

[0047] In one possible design, the communication device also includes a communication interface for inputting and / or outputting signals.

[0048] In some possible designs, the communication interface is an interface circuit used to read and write computer instructions. For example, the interface circuit is used to receive computer execution instructions (which are stored in memory and may be read directly from memory or may pass through other devices) and transmit them to the processor.

[0049] In some possible designs, this communication interface is used to communicate with modules outside the communication device.

[0050] In some possible designs, the communication device can be a chip system. When the communication device is a chip system, the chip system may include chips, or it may contain chips and other discrete components.

[0051] A ninth aspect provides a communication device, comprising: a logic circuit and an interface circuit; the interface circuit being used for inputting information and / or outputting information; the logic circuit being used to perform the method described in any of the preceding aspects, processing the input information and / or generating the output information. The communication device may be a source access network device as described in the first or third aspect, or a device included in the source access network device, such as a chip; or, the communication device may be a target access network device as described in the second, fourth, or sixth aspect, or a device included in the target access network device, such as a chip; or, the communication device may be a terminal as described in the fifth aspect, or a device included in the terminal device, such as a chip.

[0052] In a tenth aspect, a computer-readable storage medium is provided that stores a computer program or instructions that, when executed by a processor, cause the method described in any of the preceding aspects to be performed.

[0053] Eleventhly, a computer program product is provided, which, when executed by a processor, causes the method described in any of the preceding aspects to be performed.

[0054] It is understood that when the communication device provided by any of the seventh to ninth aspects is a chip, the aforementioned sending action / function can be understood as output information, and the aforementioned receiving action / function can be understood as input information.

[0055] In a twelfth aspect, a communication system is provided, which includes one or more means according to any of the above aspects.

[0056] The technical effects of any of the design methods in aspects seven through nine can be found in the technical effects of the different design methods in aspects one through six above, and will not be repeated here. Attached Figure Description

[0057] Figure 1 is a schematic diagram of the traditional HO process;

[0058] Figure 2 is a schematic diagram of the DAPS HO process;

[0059] Figure 3 is a schematic diagram of the communication system provided in an embodiment of this application;

[0060] Figure 4 is a schematic diagram of the structure of the communication device 400 provided in the embodiment of this application;

[0061] Figure 5 is a schematic diagram of an example of the communication method provided in an embodiment of this application;

[0062] Figure 6 is a schematic diagram of the DL packet drop control indication information;

[0063] Figure 7 is a schematic diagram of the PDU Set granularity discard indication information provided in the embodiments of this application;

[0064] Figure 8 is a schematic diagram showing the remaining delay of a forwarded DL data packet in the GTP-U extended subheader (Long PDCP PDU Number) provided in an embodiment of this application.

[0065] Figure 9 is a schematic diagram of the DL PDU Set information provided in an embodiment of this application;

[0066] Figure 10 is a schematic diagram of the GTP-U extended subheader supporting blind data retransmission provided in an embodiment of this application;

[0067] Figure 11 is a schematic diagram of another example of the communication method provided in the embodiments of this application;

[0068] Figure 12 is a schematic diagram of another example of the communication method provided in the embodiments of this application;

[0069] Figure 13 is a schematic diagram of another example of the communication method provided in the embodiments of this application;

[0070] Figure 14 is a schematic diagram of another example of the communication method provided in the embodiments of this application;

[0071] Figure 15 is a schematic diagram of another example of the communication method provided in the embodiments of this application;

[0072] Figure 16 is a schematic diagram of uplink data packet drop control indication information provided in an embodiment of this application;

[0073] Figure 17 is a schematic diagram of the PDU Set granularity discard indication information provided in the embodiments of this application;

[0074] Figure 18 is a schematic diagram of the communication method provided in an embodiment of this application;

[0075] Figure 19 is a schematic diagram of a communication device provided in an embodiment of this application. Detailed Implementation

[0076] In the description of this application, unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship. For example, A / B can mean A or B. "And / or" in this application is merely a description of the relationship between the related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural.

[0077] In the description of this application, unless otherwise stated, "multiple" means two or more. "At least one of the following or similar expressions" refers to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b and / or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0078] Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0079] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0080] It is understood that the term "embodiment" used throughout the specification means that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, various embodiments throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0081] It is understood that in this application, "...when" and "if" both refer to the corresponding processing that will be carried out under certain objective circumstances, and are not limited to a specific time, nor do they require a judgment action to be performed during implementation, nor do they imply any other limitations.

[0082] It is understood that some optional features in the embodiments of this application can be implemented independently in certain scenarios without relying on other features, such as the current solution on which they are based, to solve the corresponding technical problems and achieve the corresponding effects. Alternatively, they can be combined with other features as needed in certain scenarios. Correspondingly, the apparatus given in the embodiments of this application can also implement these features or functions, which will not be elaborated here.

[0083] In this application, unless otherwise specified, the same or similar parts between the various embodiments can be referred to each other. In the various embodiments of this application, unless otherwise specified or there is a logical conflict, the terminology and / or descriptions between different embodiments are consistent and can be mutually referenced. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships. The following descriptions of the embodiments of this application do not constitute a limitation on the scope of protection of this application.

[0084] To facilitate understanding, the relevant technologies of the embodiments of this application will be briefly introduced first.

[0085] I. Traditional HO process.

[0086] Figure 1 is a schematic diagram of a traditional HO (Hosting Organization) process. As shown in Figure 1, the process includes:

[0087] Step 1: The source access network device interacts with the target access network device during the HO preparation phase (handover request and handover response) based on the measurement report of the terminal device.

[0088] Step 2: The source access network device sends a handover command to the terminal device based on the handover response and configuration of the target access network device. The source access network device stops sending uplink (UL) and downlink (DL) data to the terminal device, that is, the data between the source side and the terminal device is interrupted.

[0089] Step 3: The source access network device begins forwarding downlink data to the target access network device (including downlink data that needs to be retransmitted or forwarded by the target), and sends the SN status TRANSFER.

[0090] Step 4: The terminal device receives the HO command from the source access network device and begins accessing the target access network device. Before the terminal device disconnects from the source side and establishes a connection with the target access network device, the UL or DL ​​data of the terminal device is interrupted.

[0091] Step 5: After the terminal device connects to the target access network device, the target access network device starts sending DL data packets forwarded from the source side to the terminal device, and at the same time receives NG-C connections (including NG-U TNL interactions). The access and mobility management function (AMF) instructs the user plane function (UPF) to switch the data path from the source access network device to the target access network device (providing the target access network device with UP TNL).

[0092] Step 6: The UPF sends the DL data from the target access network device and simultaneously indicates the data END marker to the source access network device. This completes the conversion of the UL or DL ​​data path from the terminal device to the target access network device.

[0093] Step 7: After receiving the path switching response from the AMF, the target access network device releases the context of the terminal device.

[0094] II. Dual Active Protocol Stack (DAPS) HO Process.

[0095] Figure 2 is a schematic diagram of the DAPS HO process. As shown in Figure 2, the process includes:

[0096] Step 1: The source access network device (NAT) initiates the HO preparation phase interaction (handover request and handover response) with the target NAT device based on the terminal device's measurement report. After receiving the handover response from the target NAT device, the source NAT device begins offloading DL data to the target NAT device; that is, DAPSDRB data is sent simultaneously through both the source and target, with the source NAT device responsible for SN allocation. While offloading DL data to the target NAT device, the source NAT device sends an Early STATUS TRANSFE message to the target NAT device (containing the COUNT of the first DL packet and the COUNT of packets to be discarded).

[0097] Step 2: The source access network device sends a handover command to the terminal device based on the target access network device's admission response and configuration. However, the source continues to send DL data to the target access network device, and the terminal device continues to send UL data to the source.

[0098] Step 3: The terminal device receives the HO command from the source access network device and begins to connect to the target access network device. After connecting to the target access network device, the terminal device stops sending UL data to the source access network device, but UL feedback continues, such as L1 CSI / L2 MAC, RLC SR, PDCP ROHC feedback, etc.

[0099] Step 4: After the terminal device connects to the target access network device, the target access network device sends a HO SUCCESS message to the source access network device, indicating that the terminal device has successfully connected to the target access network device. At this time, the source access network device stops offloading DL data to the target access network device, and instead begins forwarding DL data to the target access network device (including DL data that needs to be retransmitted or forwarded by the target side), and sends an SN status TRANSFER as a response to receiving the HO SUCCESS. At the same time, the source side stops sending UL data to the UPF.

[0100] The target access network device sends a path transition request to the AMF of the 5GC and establishes an NG-C connection (including NG-U TNL interaction) between the target access network device and the AMF. The AMF instructs the UPF data path to be transitioned from the source access network device to the target access network device (providing the target access network device with UP TNL).

[0101] Step 5: The UPF sends the DL data from the target access network device and simultaneously indicates the data END marker to the source access network device. This completes the conversion of the UL / DL data path from the terminal device to the target access network device.

[0102] Step 6: After receiving the path switching response from the AMF, the target access network device releases the context of the terminal device.

[0103] Figure 3 is a schematic diagram of a communication system provided in an embodiment of this application. As shown in Figure 3, the communication system includes a source access network device, a target access network device, and a terminal device.

[0104] In one possible implementation, a source access network device is used to send first information to a target access network device. The target access network device is used to receive the first information from the source access network device and transmit DL data to a terminal device based on the first information. The terminal device is used to receive the DL data transmitted from the target access network.

[0105] The first piece of information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device.

[0106] In one possible implementation, a source access network device is configured to receive first information from a terminal device and send the first information to a target access network device. The target access network device is configured to receive the first information from the source access network device and receive UL data from the terminal device based on the first information. The terminal device is configured to send the first information to the source access network device and transmit UL data to the target access network device based on the first information.

[0107] The first piece of information is used to indicate the discard information of UL data transmitted by the terminal device to the source access network device.

[0108] In one possible implementation, the terminal device is configured to send first information to the target access network device after switching from a source access network device to a target access network device. The target access network device is configured to receive the first information from the terminal device and receive UL data from the terminal device based on the first information.

[0109] The first piece of information is used to indicate the discard information of UL data transmitted by the terminal device to the source access network device.

[0110] Optionally, the terminal equipment involved in this application may be user equipment (UE), access terminal, terminal unit, user station, terminal station, mobile station, mobile station, remote station, remote terminal, user terminal equipment (TE), mobile device, wireless communication device, terminal agent, tablet computer, handheld device with wireless communication function, computing device or other processing device connected to a wireless modem, vehicle-mounted device, vehicle-mounted communication module, wearable device, or terminal device in a 5G network or a public land mobile network (PLMN) evolved after 5G. The access terminal may be a cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA), handheld device with wireless communication function, computing device or other processing device connected to a wireless modem, vehicle-mounted device, drone, robot, point of sale (POS) machine, customer-premises equipment (CPE), or wearable device, virtual reality (VR) device. Wireless terminals can be categorized into various types, including VR (Augmented Reality) terminal devices, wireless terminals in industrial control, self-driving, remote medical, smart grid, transportation safety, smart city, and smart home. Alternatively, a terminal can be a communication-enabled terminal within the Internet of Things (IoT), such as a V2X terminal (e.g., vehicle-to-everything (V2X) terminal, a D2D communication terminal, or an M2M communication terminal. Terminals can be mobile or fixed. Furthermore, this application does not limit the device form of the terminal; the apparatus used to implement the terminal device's function can be the terminal device itself, or it can be an apparatus capable of supporting the terminal device in implementing that function, such as a chip system. This apparatus can be installed in the terminal device or used in conjunction with the terminal device. In this application, the chip system can consist of chips or include chips and other discrete components.

[0111] Optionally, the access network equipment involved in this application (e.g., source access network equipment, target access network equipment) can be an evolved base station (NodeB or eNB or e-NodeB) in a long term evolution (LTE) system or an enhanced LTE (LTE-A) system, such as a traditional macro base station eNB and a micro base station eNB in ​​a heterogeneous network scenario. Alternatively, it can include a next-generation node B (gNB) in a new radio (NR) system. Alternatively, it can include a transmission reception point (TRP), a home base station (e.g., a home evolved NodeB, or a home Node B, HNB), a base band unit (BBU), a base band pool (BBU pool), or a wireless fidelity (WiFi) access point (AP), etc. Alternatively, it can include base stations in non-terrestrial networks (NTNs), i.e., those deployed on flying platforms or satellites. In NTNs, access network devices can act as Layer 1 (L1) relays, base stations, or integrated access and backhaul (IAB) nodes. Alternatively, access network devices can be devices that implement base station functions in IoT, such as those implementing base station functions in drone communication, V2X, D2D, or machine-to-machine (M2M) communication.

[0112] In some possible scenarios, access network equipment can also be modules or units capable of implementing some of the functions of a base station. For example, the first network device can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU and DU can be set up separately or included in the same network element, such as in a baseband unit (BBU). The RU can be included in radio equipment or radio units, such as in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0113] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, an access network device can be a network device or a module of a network device in an Open Radio Access Network (ORAN) system. In an ORAN system, CU can also be called open (O)-CU, DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through a software module, a hardware module, or a combination of a software module and a hardware module.

[0114] Optionally, the base station in the embodiments of this application may include various forms of base stations, such as: macro base station, micro base station (also known as small station), relay station, access point, home base station, TRP, transmitting point (TP), mobile switching center, etc., and the embodiments of this application do not specifically limit them.

[0115] Optionally, the user plane function network element involved in this application can be a UPF network element of the 5G communication architecture, or a network element with user plane function network element function in other communication systems. The session management function network element involved in this application can be an SMF network element of the 5G communication architecture, or a network element with session management function network element function in other communication systems. This application does not limit this.

[0116] The functions of the access network equipment (source access network equipment, target access network equipment) and terminal equipment involved in this application can be implemented by the communication device 400 in FIG4. FIG4 is a schematic diagram of the structure of the communication device 400 provided in the embodiment of this application. The communication device 400 includes one or more processors 401, communication lines 402, and at least one communication interface (FIG4 is only an example illustrating the inclusion of a communication interface 404 and a processor 401), and optionally may also include a memory 403.

[0117] The processor 401 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits used to control the execution of the program of the present application.

[0118] Communication line 402 may include a path for connecting different components.

[0119] The communication interface 404 can be a transceiver module used to communicate with other devices or communication networks, such as Ethernet, RAN, and wireless local area networks (WLAN). For example, the transceiver module can be a transceiver or similar device. Optionally, the communication interface 404 can also be a transceiver circuit located within the processor 401, used to implement the processor's signal input and signal output.

[0120] Memory 403 can be a device with storage function. For example, it can be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions; random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions; electrically erasable programmable read-only memory (EEPROM); compact disc read-only memory (CD-ROM) or other optical disc storage; optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.); magnetic disk storage media or other magnetic storage devices; or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory can exist independently and be connected to the processor via communication line 402. Memory can also be integrated with the processor.

[0121] The memory 403 stores computer execution instructions for implementing the scheme of this application, and the processor 401 controls the execution. The processor 401 executes the computer execution instructions stored in the memory 403, thereby implementing the communication method provided in the embodiments of this application.

[0122] Alternatively, in this embodiment, the processor 401 may execute the processing-related functions of the communication method provided in the following embodiments of this application, and the communication interface 404 may be responsible for communicating with other devices or communication networks. This embodiment does not specifically limit this.

[0123] Optionally, the computer execution instructions in the embodiments of this application may also be referred to as application code, and the embodiments of this application do not specifically limit this.

[0124] In a specific implementation, as one example, processor 401 may include one or more CPUs, such as CPU0 and CPU1 in FIG4.

[0125] In a specific implementation, as one embodiment, the communication device 400 may include multiple processors, such as processors 407 and 401 in FIG. 4. Each of these processors may be a single-core processor or a multi-core processor. The processors here may include, but are not limited to, at least one of the following: a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a microcontroller unit (MCU), or an artificial intelligence processor, etc., and various computing devices that run software. Each computing device may include one or more cores for executing software instructions to perform calculations or processing.

[0126] In a specific implementation, as one embodiment, the communication device 400 may further include an output device 405 and an input device 406. The output device 405 communicates with the processor 401 and can display information in various ways. For example, the output device 405 may be a liquid crystal display (LCD), a light-emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector, etc. The input device 406 communicates with the processor 401 and can receive user input in various ways. For example, the input device 406 may be a mouse, keyboard, touchscreen device, or sensing device, etc.

[0127] The aforementioned communication device 400 may sometimes be referred to as a communication device, which can be a general-purpose device or a special-purpose device. For example, the communication device 400 may be a desktop computer, a portable computer, a web server, a handheld computer (personal digital assistant, PDA), a mobile phone, a tablet computer, a wireless terminal device, an embedded device, or a device with a similar structure to that shown in Figure 4. The embodiments of this application do not limit the type of communication device 400.

[0128] Furthermore, the composition shown in Figure 4 does not constitute a limitation on the communication device. In addition to the components shown in Figure 4, the communication device may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0129] The communication method provided in the embodiments of this application will now be described with reference to the communication system shown in Figure 3.

[0130] It should be noted that in the following embodiments of this application, the message names, parameter names, or information names between network elements are just examples. Other names may also be used in other embodiments. The communication method provided in this application does not specifically limit these names.

[0131] It is understood that in the embodiments of this application, each network element can execute some or all of the steps in the embodiments of this application. These steps or operations are merely examples, and the embodiments of this application can also perform other operations or variations of various operations. Furthermore, the steps can be executed in different orders as presented in the embodiments of this application, and it is not necessary to execute all the operations in the embodiments of this application.

[0132] Figure 5 is a schematic diagram of an example of the communication method provided in this application embodiment. This method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the entity executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, or processing module in the source access network device; the entity executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, or processing module in the target access network device; the entity executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, or processing module in the terminal device. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single executing entity (e.g., the source access network device, target access network device, and terminal device) can also be divided into multiple executing entities, which can be logically and / or physically separated. For example, as shown in Figure 5, method 500 includes at least one of the following steps:

[0133] S510, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0134] In this embodiment of the application, the first information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device.

[0135] For example, the data loss information of DL data transmitted from the source access network device to the terminal device can be that the DL data transmitted from the source access network device to the terminal device has been lost. Optionally, the reason for the packet loss can be that the DL data transmitted from the source access network device to the terminal device exceeds the transmission delay budget, or the reason for the packet loss can be other reasons, which are not limited in this embodiment. Alternatively, the data loss information of DL data transmitted from the source access network device to the terminal device can also be other information, which are not limited in this embodiment.

[0136] In one possible implementation, the first information can be transmitted via the Xn-C interface. Alternatively, in other words, the first information can be carried in control plane information transmitted between the source access network device and the target access network device; this embodiment of the application does not limit this.

[0137] In this embodiment of the application, the discard information of the DL data indicated by the first information can be discard information at the data packet granularity, and the first information can be transmitted through the Xn-C interface message.

[0138] Optionally, the first information can be carried in a newly added control message. Alternatively, the first information can be carried in a newly added field of an existing control message. For example, the first information can be carried in a newly added field of a sequence status transmission (SN STATUS TRANSFER) message. Another example is that the first information can be carried in a newly added field of an early status transmission (EARLY STATUS TRANSFER) message.

[0139] In this embodiment of the application, the first information may include one or more of the following: loss status information of at least one business data unit, or the sequence number or COUNT value of the first lost data.

[0140] For example, the existing SN STATUS TRANSFER contains the following information for each data radio bearer (DRB) to be forwarded:

[0141] DRB ID: Indicates the bearer identifier of the data that needs to be forwarded.

[0142] Receive Status of PDCP SDU for UL: This indicates the reception status of the uplink data currently carried by the source access network device during the HO process, i.e., which UL PDCP SDUs were not correctly received by the source access network device and which UL PDCP SDUs were correctly received by the source access network device. Optionally, the source access network device can indicate this information to the target access network device using a bitmap.

[0143] Uplink COUNT Value (UL COUNT Value): This indicates the PDCP COUNT value of the first UL data packet that the source access network device indicated was not correctly accepted. This IE, together with the Receive Status Of PDCP SDU for UL, allows the target access network device to confirm the acceptance status of the UL data for this DRB.

[0144] Downlink COUNT Value (DL COUNT Value): This represents the COUNT value corresponding to the first PDCP SN that the target access network device needs to allocate PDCP SN for downlink. When the target access network device receives this IE, it will start DL data numbering from the PDCP SN indicated by this IE for packets that do not specify a PDCP SN.

[0145] Furthermore, the following fields can be added to the existing SN STATUS TRANSFER:

[0146] The loss status of the downlink PDCN SDU (i.e., an example of the loss status information of at least one service data unit) (Discard Status of PDCP SDU for DL): For example, when PDCP SN = 12 bits, it is BIT STRING (1..2048), and when PDCP SN = 18 bits, it is GBIT STRING (1..131072). This value is used to indicate the discard status information of the currently carried downlink DL data by the source access network device during the HO process, that is, which DL PDCP SDUs were not discarded by the source access network device and which DL PDCP SDUs have been discarded by the source access network device. The source access network device indicates this information to the target access network device through a bitmap. Among them, the Nth bit represents the discard status of the DL PDCP SDU at the position (N + First Discard PDCP SDU for DL) modulo (1 + the maximum value of PDCP SN).

[0147] Specifically, bit 0 indicates that the PDCP SDU has not been discarded; bit 1 indicates that the PDCP SDU has been discarded.

[0148] The first lost DL data's COUNT value (First Discard COUNT for DL): For example, `COUNT Value for PDCP SN Length 18` or `COUNT Value for PDCP SN Length 18` represents the PDCP COUNT value of the first DL data packet dropped by the source access network device due to timeout, as indicated by the source access network device. This IE, together with the Discard Status Of PDCP SDU for DL, allows the target base station to confirm the DL data loss status of the DRB.

[0149] For example, in the existing Early STATUS TRANSFER, each data bearer DRB to be forwarded contains the following information:

[0150] DRB ID: Indicates the bearer identifier of the data that needs to be forwarded;

[0151] FIRST DL COUNT Value: Used to indicate the PDCP COUNT value of the first DL data packet forwarded by the source access network device to the target access network device during the HO process.

[0152] Furthermore, the following fields can be added to the existing Early STATUS TRANSFER:

[0153] Discard Status of PDCP SDU for DL: For example, when PDCP SN = 12 bits, it is BIT STRING (1..2048), and when PDCP SN = 18 bits, it is GBIT STRING (1..131072). This value is used to indicate the discard status information of downlink DL data forwarded to the target base station by the source access network device instructing the target access network device during the HO process, that is, which DL PDCP SDUs were not discarded by the source access network device and which DL PDCP SDUs have been discarded by the source access network device. The source access network device may not send discarded data packets to the terminal device. Optionally, the source access network device can instruct the target access network device on this information through a bitmap. Wherein, the Nth bit represents the discard status of the DL PDCP SDU at position (N + First Discard PDCP SDU for DL) modulo (1 + maximum value of PDCP SN).

[0154] Specifically, bit 0 indicates that the PDCP SDU should be discarded and not sent to the terminal device; bit 1 indicates that the PDCP SDU should not be discarded and can be sent to the terminal device.

[0155] First Discard COUNT for DL: For example, `COUNT Value for PDCP SN Length 18` or `COUNT Value for PDCP SN Length 18` represents the PDCP COUNT value of the first DL packet discarded by the source access network device due to timeout, as indicated by the source access network device. Optionally, this IE can be combined with `Discard Status Of PDCP SDU for DL` to allow the target access network device to confirm the discarding status of the DL data in the DRB.

[0156] In another possible implementation, the first information can be transmitted via the Xn-U interface. Alternatively, in other words, the first information can be carried within user plane information.

[0157] In this embodiment of the application, the discard information of DL data transmitted from the source access network device to the terminal device indicated by the first information can be discard information at the data packet granularity, and thus the first information can be transmitted through the Xn-U interface.

[0158] Optionally, the first information can be carried in the newly added extended subheader of the GTP-U tunnel. Optionally, the first information can be carried in the newly added field of the GTP-U tunnel extended subheader; this embodiment of the application does not limit this.

[0159] In this embodiment of the application, the first information includes one or more of the following: data type, PDU type, sequence number or COUNT value of data discarded by the source access network device, or loss status information of at least one service data unit.

[0160] For example, the source access network device can construct a control indication message (i.e., first information) on the GTP-U tunnel to indicate the discarding of DL data packets, and then send it to the target access network device. Optionally, this discard control indication message has a higher priority than the forwarded data, that is, the source access network device prioritizes forwarding the discard control message before forwarding the DL data.

[0161] For example, Figure 6 is a schematic diagram of the drop control indication information of DL packets. As shown in Figure 6, the drop control indication information includes the following fields:

[0162] D / C{1bit}: Used to indicate whether the data forwarded by the GTP-U source access network device to the target access network device is a Data PDU or a Control PDU. The specific indication method is shown in Table 1 below.

[0163] Table 1

[0164] Of course, bit 0 can also be used to represent the data PDU and bit 1 to indicate the control PDU, but this application does not limit this.

[0165] PDU type{3bits}: Used to indicate the type of PDCP control message. The specific indication method is shown in Table 2 below.

[0166] Table 2

[0167] FDC{32bits}: Used to indicate the smallest COUNT value among all discarded PDCP SDUs from the source access network device.

[0168] Discard Bitmap {Variable length, can be 0}: In this embodiment, the discard information of DL data indicated by the first information can also be the discard information at the PDU Set granularity. Thus, the first information can be transmitted through the Xn-U interface. The specific indication method is shown in Table 3 below.

[0169] Table 3

[0170] In this embodiment of the application, the first information includes one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0171] For example, for the data sender (e.g., the source access network device), PDU Set-level discarding is supported. That is, when a PDU Set supports PSIHI (PDU Set Integrity Requirements), if one data packet in the PDU Set is lost, the entire PDU Set must be discarded. This mode of data packet discarding may also occur during DL forwarding in a HO scenario from the source access network device to the target access network device. Based on this, the source access network device needs to instruct the target access network device about the data packet discarding information of the PDU Set through the Xn-U interface. This discarding information is contained in the PDU Set Information container of the GTP-U tunnel of the Xn-U interface.

[0172] For example, Figure 7 is a schematic diagram of PDU Set granularity discard instruction information provided in an embodiment of this application. As shown in Figure 7, the discard instruction information includes:

[0173] Downlink PDU Set Discard Indication (PDU Type 1):

[0174] This frame is used by the source access network device to indicate the dropping of the entire PDU Set data packet or the dropping of certain data packets in the PDU Set.

[0175] The lost PDU Set sequence number (DPSSN): For example, this information can occupy 10 bits, representing the SN information of the PDU Set dropped in the DL packets of the current QoS flow, as indicated by the source access network device to the target access network device. Optionally, a drop indication can contain multiple DPSSNs to indicate multiple dropped PDU Sets.

[0176] The sequence number (DPSN) of the lost PDU within a PDU Set: For example, this information can occupy 10 bits, representing the SN information of certain packets in the PDU Set that the source access network device instructed the target access network device to drop in the DL packets of the current QoS flow. Optionally, a drop indication can include multiple DPSNs in the PDU Set to indicate that there are multiple packets in the current PDU Set that need to be dropped.

[0177] In this embodiment of the application, the target access network device can determine the discard information of the DL data transmitted from the source access network device to the terminal device based on the first information.

[0178] For example, when the target access network device receives the SN STATUS TRANSFER status report from the source access network device, it determines the DL packet dropping status of the source access network device based on the relevant fields in the report. If the target access network device determines that the fields "Discard Status Of PDCP SDU for DL" and "First Discard COUNT for DL" in the message are valid, the target access network device understands that the source access network device detected DL packet dropping during the HO process. The target access network device further reads the PDCP SN corresponding to the DL COUNT value in the "First Discard COUNT for DL" field and determines it to be the first DL packet dropped by the source access network device during the HO process. Starting from the first dropped DL packet, the target access network device further reads the DL data dropping information according to the "Discard Status Of PDCP SDU for DL" field, and the packet with an indication of "1" is the dropped SN. In this way, the target access network device obtains information on all DL packet dropping information from the source access network device.

[0179] For example, when the target access network device receives the Early STATUS TRANSFER information from the source access network device, it determines the DL packet dropping status of the source access network device based on the relevant fields in the information. If the target access network device determines that the fields "Discard Status Of PDCP SDU for DL" and "First Discard COUNT for DL" in the message are valid, the target access network device understands that the source access network device detected DL packet dropping during the HO process. The target access network device further reads the PDCP SN corresponding to the DL COUNT value in the "First Discard COUNT for DL" field to determine that it is the first DL packet dropped by the source access network device during the HO process. Starting from the first dropped DL packet, the target access network device further reads the DL data dropping information according to the "Discard Status Of PDCP SDU for DL" field, and the packet with an indication of "1" is the dropped SN. In this way, the target access network device obtains information on all DL packet dropping information of the source access network device.

[0180] For example, the target access network device obtains information on all data packets dropped by the source access network device through the DL drop control indication information, as described above, and will not be repeated here.

[0181] Alternatively, the target access network device can obtain the PDU Set or information on dropped data packets in the PDU Set of the DL data packets dropped by the source access network device through the drop indication information at the PDU Set granularity. This can be referred to the above description and will not be repeated here.

[0182] It should be noted that, as described in related technology 2 above, the source access network device can also directly send the first information to the terminal device. The first information can be referred to the description in the above embodiments, and will not be repeated here.

[0183] In step S520, the target access network device sends first information to the terminal device. Correspondingly, the terminal device receives the first information from the target access network device.

[0184] In this embodiment of the application, the target access network device sends first information to the terminal device, which enables the terminal device to determine the discard information of the DL data transmitted by the source access network device to the terminal device, so that the terminal device no longer needs to wait for the DL data discarded by the source access network device.

[0185] In this embodiment, the first information sent by the target access network device to the terminal device can be carried in a newly added field of an existing message. For a detailed description of the first information carried in a newly added field of an existing message, please refer to the above description, which will not be repeated here. Alternatively, the first information sent by the target access network device to the terminal device can be carried in a newly added message, as described above, which will not be repeated here.

[0186] The communication method provided in this application embodiment involves a source access network device sending first information to a target access network device, and the target access network device sending first information to a terminal device. The first information indicates whether data transmitted from the source access network device to the terminal device has been discarded. By receiving the first information from the source access network device, the target access network device can transmit valid data or data not discarded by the source access network device to the terminal device based on the first information, thereby improving the efficiency of data transmission and preventing resource waste caused by the source access network device transmitting data that has already been discarded by the source access network device to the terminal device. The terminal device receiving the first information from the target access network device can avoid unnecessary waiting. The communication method provided in this application embodiment ensures support for low-latency services.

[0187] Optionally, the communication method provided in this application embodiment also includes (it is worth noting that the following contents can also be implemented independently, and are not limited here):

[0188] S530, the source access network device sends second information to the target access network device. Correspondingly, the target access network device receives the second information from the source access network device.

[0189] In this embodiment, the second information is used to indicate the remaining delay information of the DL data transmitted from the source access network device to the target access network device. The second information can be transmitted via the Xn-U interface.

[0190] In one possible implementation, the second information is carried in a newly added field of the GTP-U tunnel extension subheader. In another possible implementation, the second information is carried in a newly added extension subheader of the GTP-U tunnel.

[0191] Alternatively, as a possible implementation, the source access network device can also transmit second information to the target access network device via the Xn-C interface.

[0192] In addition to indicating the remaining delay, the second information can also indicate other information related to the remaining delay, such as the remaining delay of the data packet SN segment (indicated by time zone segment), or the delay level, such as very urgent, moderately urgent, not urgent, etc. Alternatively, the second information may only indicate the remaining delay of certain data in the data transmitted from the source access network device to the target access network device, which is not limited in this embodiment of the application.

[0193] It should be noted that the remaining delay indicated by the second information can be the remaining delay of the air interface transmission of the source access network device, or it can be the remaining transmission delay after considering the delay of the Xn interface transmission. This application embodiment does not limit this. The remaining delay on the Xn interface can also be automatically reduced by the target access network device after receiving the information. This application embodiment does not limit this as well.

[0194] In one possible implementation of this application, the remaining latency of the data transmitted from the source access network device to the target access network device indicated by the second information can be the remaining latency at the data packet granularity. Alternatively, in another possible implementation of this application, the remaining latency of the data transmitted from the source access network device to the target access network device indicated by the second information can also be at the PDU Set granularity; this application does not limit this aspect.

[0195] In this embodiment of the application, during the HO process, for DL ​​data packets forwarded to the target access network device, the source access network device can indicate to the target base station the remaining delay of the DL data packet's discard timer.

[0196] For example, Figure 8 is a schematic diagram showing how the source access network device, according to an embodiment of this application, indicates the remaining delay of a forwarded DL data packet in the GTP-U extended subheader (Long PDCP PDU Number). As shown in Figure 8, the GTP-U extended subheader of the DL data packet includes:

[0197] Remaining time: For example, this information can be 1bti, representing the remaining time of the currently forwarded DL data packet on the air interface. The value range can include one or more of the following: ENUMERATED{ms0,ms2,ms4,ms6,ms8,ms10,ms12,ms14,ms18,ms22,ms26,ms30,ms40,ms50,ms75,ms100}.

[0198] S540: The target access network device transmits data to the terminal device based on the remaining delay.

[0199] For example, the target access network device can read the "Remaining time" in the GTP-U extended subheader to know the remaining transmission time of the data packet on the air interface. The target access network device starts the target-side drop timer with the remaining time and performs target-side air interface scheduling and transmission based on the remaining time.

[0200] It should be noted that the source access network device may also forward the remaining delay information of the local timer of the UL data received by the source access network device as the receiving end. This local timer is the basis for the source access network device to determine when the data packet will time out when receiving the uplink data from the terminal device.

[0201] This scheme enables the source access network device to indicate the remaining latency of DL data to the target access network device. In turn, the target access network device can perform resource scheduling and air interface transmission based on the remaining latency, ensuring the timeliness of forwarded data transmission over the air interface.

[0202] Optionally, the communication method provided in this application embodiment also includes (it is worth noting that the following contents can also be implemented independently, and are not limited here):

[0203] In S550, the source access network device sends third information to the target access network device. Correspondingly, the target access network device receives the third information from the source access network device.

[0204] In this embodiment, the third information is used to indicate the redundancy ratio of the PDU Set transmitted from the source access network device to the target access network device. This third information can be transmitted via the Xn-U interface.

[0205] In one possible implementation, the third information is carried in a newly added field of the GTP-U tunnel extension subheader. In another possible implementation, the third information is carried in a newly added extension subheader of the GTP-U tunnel.

[0206] Alternatively, as a possible implementation, the third information can be transmitted via the Xn-C interface. For example, the third information indicates the content ratio information of the current QoS flow (e.g., when all PDU sets of a QoS flow have the same content ratio information).

[0207] In addition, the source access network device can also indicate the dynamic QoS indication of the QoS flow to the target access network device, that is, the standard QoS flow supports dynamically changing QoS profile information.

[0208] In this application embodiment, the third information may include one or more of the following: PDU type, or the redundancy ratio of the PDU Set.

[0209] For example, Figure 9 is a schematic diagram of DL PDU Set information provided in an embodiment of this application. As shown in Figure 9, the information includes:

[0210] PDU Type: For example, this information can be 4 bits, used to indicate the information referred to by the current control message. "PDU Type=2" indicates that the current indication is the content ratio information of the PDU Set of the DL data packet in the current QoS flow, that is, the data ratio information required by the application layer to complete the decoding of the PDU Set.

[0211] PDU Set Redundancy Ratio (PSCR): For example, this information can be 4 bits, representing the content ratio information of the PDU Set in the DL data packet in the current QoS flow, as instructed by the source access network device to the target access network device. That is, the data ratio information required by the application layer of the PDU Set to complete the decoding of the PDU Set.

[0212] S560, the target access network device transmits the PDU Set to the terminal device according to the redundancy ratio indicated by the third information.

[0213] For example, by reading the "PDU Set content ratio" information in the GTP-U extended subheader, the target access network device can understand the proportion of data packets required for air interface data transmission of the PDU Set. The target access network device can then send air interface data according to this proportion. When the proportion of successfully transmitted data packets reaches the content ratio, the target access network device can discard the unsent data packets.

[0214] This scheme allows the source access network device to indicate the redundancy ratio of the target access network device's PDU Set, which in turn enables the target access network device to perform resource scheduling and air interface transmission based on the redundancy ratio, thereby reducing resource waste.

[0215] Optionally, the communication method provided in this application embodiment also includes (it is worth noting that the following contents can also be implemented independently, and are not limited here):

[0216] S570, the source access network device sends the fourth information to the target access network device. Correspondingly, the target access network device receives the fourth information from the source access network device.

[0217] In this embodiment, the fourth information is used to indicate whether the DL data transmitted from the source access network device to the target access network device supports blind retransmission. The fourth information is transmitted via the Xn-U interface.

[0218] In one possible implementation, the fourth information is carried in a newly added field of the GTP-U tunnel extension subheader. In another possible implementation, the fourth information is carried in a newly added extension subheader of the GTP-U tunnel.

[0219] In one possible implementation of this application, the data indicating whether retransmission is supported, transmitted from the source access network device to the target access network device, as indicated by the fourth information, can be data at the data packet granularity. Alternatively, in another possible implementation of this application, the data transmitted from the source access network device to the target access network device, as indicated by the fourth information, can also be data at the PDU Set granularity; this application does not limit this aspect.

[0220] For example, in the data forwarding process of the HO scenario, the source access network device needs to indicate in the GTP-U extended subheader of each forwarded data packet on the GTP-U channel where the forwarded data DRB of Xn-U resides whether the DL data needs to be blindly retransmitted by the target access network device. Based on this, the GTP-U extended subheader needs to be enhanced. Figure 19 is a schematic diagram of the GTP-U extended subheader supporting blind data retransmission provided in an embodiment of this application. As shown in Figure 19, the extended subheader includes:

[0221] Retransmission Indication: For example, this indication information can be 1 bit, indicating whether the currently forwarded DL data packet supports air interface blind retransmission processing. In one possible implementation, bit "0" indicates that air interface blind retransmission of the data packet by the target access network device is not supported, and bit "1" indicates that air interface blind retransmission of the data packet by the target access network device is supported. Alternatively, in another possible implementation, bit "1" indicates that air interface blind retransmission of the data packet by the target access network device is not supported, and bit "0" indicates that air interface blind retransmission of the data packet by the target access network device is supported.

[0222] In step S580, the target access network device retransmits data to the terminal device according to the retransmission support indicated by the fourth information. Correspondingly, the terminal device receives the retransmitted data from the target access network device.

[0223] For example, the target access network device can learn whether it needs to blindly retransmit the data packet to the terminal device over the air interface by reading the "Retransmission Indication" in the GTP-U extended subheader.

[0224] This scheme instructs the target access network device on DL data blind retransmission information by the source access network device, which enables the target access network device to blindly retransmit the corresponding DL data to the terminal device based on the instruction, thus ensuring the reliability of DL forwarding data transmission over the air interface.

[0225] Optionally, the communication method provided in this application embodiment also includes (it is worth noting that the following contents can also be implemented independently, and are not limited here):

[0226] S590, the source access network device sends the fifth information to the target access network device. Correspondingly, the target access network device receives the fifth information from the source access network device.

[0227] In this embodiment, the fifth piece of information is used to indicate the blind retransmission conditions for data transmitted from the source access network device to the target access network device. This fifth piece of information can be transmitted via the Xn-C interface.

[0228] In this embodiment of the application, the fifth piece of information may include one or more of the following: a remaining delay threshold, or an importance threshold.

[0229] Exemplarily, for the DL data forwarded during the HO process, the source access network device can further support the blind retransmission processing mechanism from the target access network device to the terminal device. To support this mechanism, the source access network device needs to indicate the forwarded DL data packets that can support blind retransmission. Specifically, during the data forwarding process in the HO scenario, the source access network device indicates the limiting conditions for blind retransmission to the target access network device through Xn-C, such as the remaining time threshold or the PSI level threshold. Specifically, the source access network device needs to indicate the threshold information about the delay threshold or the packet importance level to the target access network device through the SN STATUS TRANSFER message or the Early STATUS TRANSFER message of Xn-C. Specifically, the following thresholds need to be included in the message:

[0230] Remaining time threshold: {INTEGER(1..64)}, this threshold information is used by the target access network device to judge the remaining delay threshold for whether the DL forwarded data can be blindly retransmitted. If the remaining delay of a DL forwarded data < Remaining time threshold, then the target access network device will judge that the forwarded DL data can be blindly retransmitted. Otherwise, no blind retransmission is performed on this data.

[0231] PDU Set Importance (PSI) Threshold: {INTEGER(1..15)}, this threshold information is used by the target access network device to judge the importance threshold for whether the DL forwarded data can be blindly retransmitted. The higher the value of PSI, the lower the importance. If the target access network device judges that the PSI of a DL forwarded data < PDU Set Importance (PSI) Threshold, then the target access network device will judge that the forwarded DL data can be blindly retransmitted. Otherwise, no blind retransmission is performed on this data.

[0232] S591, the target access network device retransmits the data to the terminal device according to the fifth information.

[0233] For example, by receiving the "Remaining timethreshold" or "PDU Set Importance (PSI) Threshold" information in the SN STATUS TRANSFER or Early STATUS TRANSFER message of Xn-C, the target access network device can know whether to perform a wireless air interface blind retransmission of a forwarded DL data. When the remaining delay or importance of a data meets the delay or importance threshold requirements indicated by the source access network device, the target access network device will perform an air interface blind retransmission of the data.

[0234] This scheme uses the remaining delay threshold and importance threshold information of the DL data to indicate to the target access network device whether the DL data supports blind retransmission by the source access network device. This allows the target access network device to determine whether a forwarded DL data can be blindly retransmitted to the terminal device based on the remaining delay or PSI importance level of a data packet, thereby ensuring the reliability of DL forwarded data transmission over the air interface.

[0235] Figure 11 is a schematic diagram of another example of the communication method provided in this application embodiment. This method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the entity executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, or processing module in the source access network device; the entity executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, or processing module in the target access network device; the entity executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, or processing module in the terminal device. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single executing entity (e.g., the source access network device, target access network device, and terminal device) can also be divided into multiple executing entities, which can be logically and / or physically separated. For example, as shown in Figure 11, method 1100 includes at least one of the following steps:

[0236] S1110, the source access network device sends the second information to the target access network device. Correspondingly, the target access network device receives the second information from the source access network device.

[0237] In this embodiment, the second information is used to indicate the remaining delay of the DL data transmitted from the source access network device to the target access network device. A description of the second information can be found in the description in method 500, and will not be repeated here.

[0238] S1120, the target access network device transmits data to the terminal device based on the remaining delay.

[0239] In this embodiment of the application, the relevant description of the target access network device transmitting DL data to the terminal device according to the remaining delay can be referred to the relevant description in method 500, and will not be repeated here.

[0240] Optionally, the communication method provided in this application embodiment further includes:

[0241] S1130, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0242] In this embodiment, the first information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device. A description of the first information can be found in the relevant description in method 500, and will not be repeated here.

[0243] S1140, the target access network device sends first information to the terminal device. Correspondingly, the terminal device receives the first information from the target access network device.

[0244] In this embodiment of the application, the relevant description of the target access network device sending the first information to the terminal device can be referred to the relevant description in method 500, and will not be repeated here.

[0245] Optionally, the communication method provided in this application embodiment further includes:

[0246] S1150, the source access network device sends third information to the target access network device. Correspondingly, the target access network device receives the third information from the source access network device.

[0247] In this embodiment, the third information is used to indicate the redundancy ratio of the PDU Set transmitted from the source access network device to the target access network device. A description of the third information can be found in the relevant description in method 500, and will not be repeated here.

[0248] S1130, the target access network device transmits the PDU Set to the terminal device according to the redundancy ratio indicated by the third information.

[0249] In this embodiment of the application, the relevant description of the target access network device transmitting PDU Set to the terminal device according to the redundancy ratio indicated by the third information can be referred to the relevant description in method 500, and will not be repeated here in this embodiment of the application.

[0250] Optionally, the communication method provided in this application embodiment further includes:

[0251] S1170, the source access network device sends the fourth information to the target access network device. Correspondingly, the target access network device receives the fourth information from the source access network device.

[0252] In this embodiment, the fourth information is used to indicate whether the DL data transmitted from the source access network device to the target access network device supports blind retransmission. A description of the fourth information can be found in the relevant description in method 500, and will not be repeated here.

[0253] S1180, the target access network device retransmits data to the terminal device according to the retransmission support indicated by the fourth information. Accordingly, the terminal device receives the retransmitted data from the target access network device.

[0254] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the instruction of the fourth information can be referred to the relevant description in method 500, and will not be repeated here.

[0255] Optionally, the communication method provided in this application embodiment further includes:

[0256] S1190, the source access network device sends the fifth information to the target access network device. Correspondingly, the target access network device receives the fifth information from the source access network device.

[0257] In this embodiment, the fifth information is used to indicate the blind retransmission conditions for data transmitted from the source access network device to the target access network device. A description of the fifth information can be found in the description in method 500, and will not be repeated here.

[0258] S1191, the target access network device retransmits data to the terminal device according to the fifth information.

[0259] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the fifth information can be referred to the relevant description in method 500, and will not be repeated here.

[0260] Figure 12 is a schematic diagram of another example of the communication method provided in this application embodiment. This method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the entity executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, or processing module in the source access network device; the entity executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, or processing module in the target access network device; the entity executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, or processing module in the terminal device. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single executing entity (e.g., the source access network device, target access network device, and terminal device) can also be divided into multiple executing entities, which can be logically and / or physically separated. For example, as shown in Figure 12, method 1200 includes at least one of the following steps:

[0261] S1210, the source access network device sends third information to the target access network device. Correspondingly, the target access network device receives the third information from the source access network device.

[0262] In this embodiment, the third information is used to indicate the redundancy ratio of the PDU Set transmitted from the source access network device to the target access network device. A description of the third information can be found in the relevant description in method 500, and will not be repeated here.

[0263] S1220, the target access network device transmits the PDU Set to the terminal device according to the redundancy ratio indicated by the third information.

[0264] In this embodiment of the application, the relevant description of the target access network device transmitting PDU Set to the terminal device according to the redundancy ratio indicated by the third information can be referred to the relevant description in method 500, and will not be repeated here.

[0265] Optionally, the communication method provided in this application embodiment further includes:

[0266] S1230, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0267] In this embodiment, the first information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device. A description of the first information can be found in the relevant description in method 500, and will not be repeated here.

[0268] S1240, the target access network device sends first information to the terminal device. Correspondingly, the terminal device receives the first information from the target access network device.

[0269] In this embodiment of the application, the relevant description of the target access network device sending the first information to the terminal device can be referred to the relevant description in method 500, and will not be repeated here.

[0270] Optionally, the communication method provided in this application embodiment further includes:

[0271] S1250, the source access network device sends second information to the target access network device. Correspondingly, the target access network device receives the second information from the source access network device.

[0272] In this embodiment, the second information is used to indicate the remaining delay of data transmitted from the source access network device to the target access network device. A description of the second information can be found in the description in method 500, and will not be repeated here.

[0273] S1260, the target access network device transmits data to the terminal device based on the remaining delay.

[0274] In this embodiment of the application, the relevant description of the target access network device transmitting data to the terminal device according to the remaining delay can be referred to the relevant description in method 500, and will not be repeated here.

[0275] Optionally, the communication method provided in this application embodiment further includes:

[0276] S1270, the source access network device sends the fourth information to the target access network device. Correspondingly, the target access network device receives the fourth information from the source access network device.

[0277] In this embodiment, the fourth information is used to indicate whether the DL data transmitted from the source access network device to the target access network device supports blind retransmission. A description of the fourth information can be found in the relevant description in method 500, and will not be repeated here.

[0278] S1280, the target access network device retransmits data to the terminal device according to the retransmission support indicated by the fourth information. Accordingly, the terminal device receives the retransmitted data from the target access network device.

[0279] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the instruction of the fourth information can be referred to the relevant description in method 500, and will not be repeated here.

[0280] Optionally, the communication method provided in this application embodiment further includes:

[0281] S1290, the source access network device sends the fifth information to the target access network device. Correspondingly, the target access network device receives the fifth information from the source access network device.

[0282] In this embodiment, the fifth information is used to indicate the blind retransmission conditions for DL ​​data transmitted from the source access network device to the target access network device. A description of the fifth information can be found in the relevant description in method 500, and will not be repeated here.

[0283] S1291, the target access network device retransmits data to the terminal device according to the fifth information.

[0284] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the fifth information can be referred to the relevant description in method 500, and will not be repeated here.

[0285] Figure 13 is a schematic diagram of another example of the communication method provided in this application embodiment. As shown in Figure 13, the method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the subject executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, processing module, etc. in the source access network device; the subject executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, processing module, etc. in the target access network device; the subject executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, processing module, etc., in this application embodiment. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single execution subject (e.g., the source access network device, the target access network device, and the terminal device) can also be divided into multiple execution subjects, which can be logically and / or physically separated. For example, as shown in Figure 13, method 1300 includes at least one of the following steps:

[0286] S1310, the source access network device sends the fourth information to the target access network device. Correspondingly, the target access network device receives the fourth information from the source access network device.

[0287] In this embodiment, the fourth information is used to indicate whether the data transmitted from the source access network device to the target access network device supports blind retransmission. A description of the fourth information can be found in the relevant description in method 500, and will not be repeated here.

[0288] S1320, the target access network device retransmits data to the terminal device according to the retransmission support indicated by the fourth information. Accordingly, the terminal device receives the retransmitted data from the target access network device.

[0289] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the instruction of the fourth information can be referred to the relevant description in method 500, and will not be repeated here.

[0290] Optionally, the communication method provided in this application embodiment further includes:

[0291] S1330, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0292] In this embodiment, the first information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device. A description of the first information can be found in the relevant description in method 500, and will not be repeated here.

[0293] S1340, the target access network device sends first information to the terminal device. Correspondingly, the terminal device receives the first information from the target access network device.

[0294] In this embodiment of the application, the relevant description of the target access network device sending the first information to the terminal device can be referred to the relevant description in method 500, and will not be repeated here.

[0295] Optionally, the communication method provided in this application embodiment further includes:

[0296] S1350, the source access network device sends second information to the target access network device. Correspondingly, the target access network device receives the second information from the source access network device.

[0297] In this embodiment, the second information is used to indicate the remaining delay of the DL data transmitted from the source access network device to the target access network device. A description of the second information can be found in the description in method 500, and will not be repeated here.

[0298] S1360, the target access network device transmits data to the terminal device based on the remaining delay.

[0299] In this embodiment of the application, the relevant description of the target access network device transmitting data to the terminal device according to the remaining delay can be referred to the relevant description in method 500, and will not be repeated here.

[0300] Optionally, the communication method provided in this application embodiment further includes:

[0301] S1370, the source access network device sends third information to the target access network device. Correspondingly, the target access network device receives the third information from the source access network device.

[0302] In this embodiment, the third information is used to indicate the redundancy ratio of the PDU Set transmitted from the source access network device to the target access network device. A description of the third information can be found in the relevant description in method 500, and will not be repeated here.

[0303] S1380, the target access network device transmits the PDU Set to the terminal device according to the redundancy ratio indicated by the third information.

[0304] In this embodiment of the application, the relevant description of the target access network device transmitting PDU Set to the terminal device according to the redundancy ratio indicated by the third information can be referred to the relevant description in method 500, and will not be repeated here.

[0305] Optionally, the communication method provided in this application embodiment further includes:

[0306] S1390, the source access network device sends the fifth information to the target access network device. Correspondingly, the target access network device receives the fifth information from the source access network device.

[0307] In this embodiment, the fifth information is used to indicate the blind retransmission conditions for DL ​​data transmitted from the source access network device to the target access network device. A description of the fifth information can be found in the relevant description in method 500, and will not be repeated here.

[0308] S1391, the target access network device retransmits data to the terminal device according to the fifth information.

[0309] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the fifth information can be referred to the relevant description in method 500, and will not be repeated here.

[0310] Figure 14 is a schematic diagram of another example of the communication method provided in this application embodiment. As shown in Figure 14, the method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the subject executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, processing module, etc. in the source access network device; the subject executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, processing module, etc. in the target access network device; the subject executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, processing module, etc., in this application embodiment. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single execution subject (e.g., the source access network device, the target access network device, and the terminal device) can also be divided into multiple execution subjects, which can be logically and / or physically separated. For example, as shown in Figure 14, method 1400 includes at least one of the following steps:

[0311] S1410, the source access network device sends the fifth information to the target access network device. Correspondingly, the target access network device receives the fifth information from the source access network device.

[0312] In this embodiment, the fifth information is used to indicate the blind retransmission conditions for DL ​​data transmitted from the source access network device to the target access network device. A description of the fifth information can be found in the relevant description in method 500, and will not be repeated here.

[0313] S1420, the target access network device retransmits data to the terminal device according to the fifth information.

[0314] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the fifth information can be referred to the relevant description in method 500, and will not be repeated here.

[0315] Optionally, the communication method provided in this application embodiment further includes:

[0316] S1430, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0317] In this embodiment, the first information is used to indicate the discard information of DL data transmitted from the source access network device to the terminal device. A description of the first information can be found in the relevant description in method 500, and will not be repeated here.

[0318] S1440, the target access network device sends first information to the terminal device. Correspondingly, the terminal device receives the first information from the target access network device.

[0319] In this embodiment of the application, the relevant description of the target access network device sending the first information to the terminal device can be referred to the relevant description in method 500, and will not be repeated here.

[0320] Optionally, the communication method provided in this application embodiment further includes:

[0321] S1450, the source access network device sends second information to the target access network device. Correspondingly, the target access network device receives the second information from the source access network device.

[0322] In this embodiment, the second information is used to indicate the remaining delay of data transmitted from the source access network device to the target access network device. A description of the second information can be found in the description in method 500, and will not be repeated here.

[0323] S1460, the target access network device transmits data to the terminal device based on the remaining delay.

[0324] In this embodiment of the application, the relevant description of the target access network device transmitting DL data to the terminal device according to the remaining delay can be referred to the relevant description in method 500, and will not be repeated here.

[0325] Optionally, the communication method provided in this application embodiment further includes:

[0326] S1470, the source access network device sends third information to the target access network device. Correspondingly, the target access network device receives the third information from the source access network device.

[0327] In this embodiment, the third information is used to indicate the redundancy ratio of the PDU Set transmitted from the source access network device to the target access network device. A description of the third information can be found in the relevant description in method 500, and will not be repeated here.

[0328] S1480, the target access network device transmits the PDU Set to the terminal device according to the redundancy ratio indicated by the third information.

[0329] In this embodiment of the application, the relevant description of the target access network device transmitting PDU Set to the terminal device according to the redundancy ratio indicated by the third information can be referred to the relevant description in method 500, and will not be repeated here.

[0330] Optionally, the communication method provided in this application embodiment further includes:

[0331] S1490, the source access network device sends the fourth information to the target access network device. Correspondingly, the target access network device receives the fourth information from the source access network device.

[0332] In this embodiment, the fourth information is used to indicate whether the DL data transmitted from the source access network device to the target access network device supports blind retransmission. A description of the fourth information can be found in the relevant description in method 500, and will not be repeated here.

[0333] S1491, the target access network device retransmits data to the terminal device according to the retransmission support indicated by the fourth information. Accordingly, the terminal device receives the retransmitted data from the target access network device.

[0334] In this embodiment of the application, the relevant description of the target access network device retransmitting data to the terminal device according to the instruction of the fourth information can be referred to the relevant description in method 500, and will not be repeated here.

[0335] Figure 15 is a schematic diagram of another example of the communication method provided in this application embodiment. This method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the entity executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, or processing module in the source access network device; the entity executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, or processing module in the target access network device; the entity executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, or processing module in the terminal device. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single executing entity (e.g., the source access network device, target access network device, and terminal device) can also be divided into multiple executing entities, which can be logically and / or physically separated. For example, as shown in Figure 15, method 1500 includes at least one of the following steps:

[0336] S1510, the terminal device sends first information to the source access network device. Correspondingly, the source access network device receives the first information from the terminal device.

[0337] In this embodiment of the application, the first information is used to indicate the discard information of UL data transmitted by the terminal device to the source access network device.

[0338] S1520, the source access network device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the source access network device.

[0339] In this embodiment, the source access network device sending first information to the target access network device includes: the source access network device sending first information to the target access network device via an Xn-C interface. Correspondingly, the target access network device receiving the first information from the source access network device includes: the target access network device receiving the first information from the source access network device via an Xn-C interface.

[0340] In one possible implementation, the first information is carried in the newly added message. In another possible implementation, the first information is carried in a newly added field of an existing message.

[0341] In this embodiment, the first information, indicating the discard information of UL data transmitted from the terminal device to the source access network device via the Xn-C interface, can be discard information at the data packet granularity. The first information may include one or more of the following: loss status information of at least one service data unit, or the sequence number or COUNT value of the first lost data.

[0342] For example, the first information is carried in a newly added field of the SN STATUS TRANSFER message. For a description of the first information carried in the newly added field of the SN STATUS TRANSFER message, please refer to the relevant description in method 500. It is only necessary to replace the discard information of the first information used to indicate the data to be transmitted from the source access network device to the terminal device with the discard information of the first information used to indicate the data to be transmitted from the terminal device to the source access network device, that is, to replace the downlink with the uplink. The embodiments of this application will not be described in detail here.

[0343] For example, the first information is carried in a newly added field of the EARLY STATUS TRANSFER message. Similarly, the relevant description in method 500 can be referred to, only the downlink is replaced with the uplink. The embodiments of this application will not be described again here.

[0344] In this embodiment, the source access network device sending first information to the target access network device includes: the source access network device sending the first information to the target access network device via the Xn-U interface. Correspondingly, the target access network device receiving the first information from the source access network device includes: the target access network device receiving the first information from the source access network device via the Xn-U interface.

[0345] In one possible implementation, the first information is carried in the newly added extended subheader of the GTP-U tunnel. In another possible implementation, the first information is carried in the newly added message of the extended subheader of the GTP-U tunnel.

[0346] In this embodiment, the first information, indicating the discard information of UL data transmitted by the terminal device to the source access network device via the Xn-U interface, can be discard information at the data packet granularity. The first information may include one or more of the following: data type, PDU type, sequence number or COUNT value of the data discarded by the terminal device, or, loss status information of at least one service data unit.

[0347] For example, in the data forwarding process of the HO scenario, in order to indicate to the terminal device via Xn-U the information of data packets that have timed out and been discarded, the source access network device can construct a control indication message for discarding uplink data packets on the GTP-U tunnel and send it to the target access network device. Optionally, this discard control indication message has a higher priority than the forwarded data, that is, the source access network device prioritizes forwarding the discard control message before forwarding the data. Figure 16 is a schematic diagram of the uplink data packet discard control indication message provided in an embodiment of this application. As shown in Figure 16, the uplink data packet discard control indication message includes:

[0348] D / C{1bit}: This information is used to indicate whether the data forwarded by the GTP-U source access network device to the target access network device is a Data PDU or a Control PDU. Specifically, this indication information can be shown in Table 4 below.

[0349] Table 4

[0350] It should be noted that bit 0 can also indicate that the forwarded data is a Data PDU, and bit 1 can also indicate that the forwarded data is a Control PDU. This application does not limit this.

[0351] PDU type; This information indicates the type of PDCP control message. For example, this information can occupy 3 bits. Specifically, this indication information can be shown in Table 5 below.

[0352] Table 5

[0353] FDC: For example, this information can occupy 32 bits and is used to indicate the minimum COUNT value among all discarded PDCP SDUs of the source access network device.

[0354] Discard Bitmap: This information can occupy a variable length, which can be 0 bits. It is used to indicate which UL packets forwarded by the source side were dropped and which were not dropped. The position of the Nth bit is N. Specifically, this indication information can be shown in Table 6 below.

[0355] Table 6

[0356] In this embodiment of the application, the first information, which is the UL data loss information transmitted by the terminal device to the source access network device via the Xn-U interface, can be PDU Set-level loss information. The first information may include one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDUs in the PDU Set.

[0357] For example, the terminal device can support PDU Set-level discarding. That is, when a PDU Set supports PSIHI (PDU Set Integrity Requirements), if one data packet in the PDU Set is lost, the entire PDU Set must be discarded. This data packet discarding mode may also be sent during the UL data discarding indication process in the HO scenario from the source access network device to the target access network device. Based on this, the source access network device needs to indicate data packet discarding information about the UL PDU Set to the target access network device via Xn-U. This discarding information is contained in the PDU Set Information container of the GTP-U tunnel of the Xn-U interface. It should be noted that it can support discarding indications for all data packets in the entire PDU Set, and it can also support discarding indications for some data packets in a PDU Set. Figure 17 is a schematic diagram of the PDU Set-level discarding indication information provided in an embodiment of this application. As shown in Figure 17, this information includes:

[0358] UL PDU SET DISCARD INFORMATION (PDU Type 2): This frame is used by NG-RAN node access network devices to instruct another access network device about the discarding information of a PDU Set in a QoS flow.

[0359] PDU Type: For example, this information can occupy 4 bits and is used to indicate the information referred to by the current control message. "PDU Type=2" indicates that the current indication is the PDU Set information dropped in the UL data packet in the current QoS flow. It can indicate the dropping of the entire PDU Set data packet or the dropping information of some data packets in the PDU Set.

[0360] Discard PDU Set Sequence Number (DPSSN): For example, this information can occupy 10 bits, representing the SN information of the PDU Set dropped in the UL data packet that the UE has dropped in the current QoS flow, as indicated by the source access network device to the target access network device. Optionally, a drop indication can contain multiple DPSSNs to indicate multiple dropped PDU Sets.

[0361] Discard PDU Sequence Number within a PDU Set (DPSN): For example, this information can occupy 10 bits, indicating the SN information of certain packets in the PDU Set that the UE has discarded in the current QoS flow, as instructed by the source access network device. Optionally, a discard indication can contain multiple DPSNs in the PDU Set to indicate that there are packets in the current PDU Set that need to be discarded.

[0362] S1530, the terminal device transmits data to the target access network device according to the first information. Correspondingly, the target access network device receives the data transmitted from the terminal device according to the first information.

[0363] In this embodiment of the application, the target access network device obtains information on all UL data packets discarded by the terminal device. During the HO process, the target access network device will further wait for UL data packets indicated as discarded on the air interface.

[0364] The communication method provided in this application embodiment involves a terminal device sending data loss information to a source access network device, indicating that the data being transmitted from the terminal device to the source access network device has been lost. Subsequently, the source access network device can indicate the data loss information to a target access network device, allowing the target access network device to avoid waiting for the lost data.

[0365] Figure 18 is a schematic diagram of another example of the communication method provided in this application embodiment. This method can be applied to the communication system shown in Figure 3. The method is illustrated using the interaction between a source access network device and a target access network device (optionally, a terminal device) as an example. Of course, the entity executing the action of the source access network device in this method can also be a device / module in the source access network device, such as a chip, processor, or processing unit in the source access network device; the entity executing the action of the target access network device in this method can also be a device / module in the target access network device, such as a chip, processor, or processing unit in the target access network device; the entity executing the action of the terminal device in this method can also be a device / module in the terminal device, such as a chip, processor, or processing unit in the terminal device. This application embodiment does not specifically limit this. In this application embodiment, the processing performed by a single executing entity (e.g., the source access network device, target access network device, and terminal device) can also be divided into multiple executing entities, which can be logically and / or physically separated. For example, as shown in Figure 18, method 1800 includes at least one of the following steps:

[0366] S1810, the terminal device switches from the source access network device to the target access network device.

[0367] S1820, the terminal device sends first information to the target access network device. Correspondingly, the target access network device receives the first information from the terminal device.

[0368] In this embodiment, the first information is used to indicate the discard information of UL data transmitted by the terminal device to the source access network device. That is, when the terminal device switches from the source access network device to the target access network device, it can directly indicate the discard information of the data transmitted by the terminal device to the source access network device to the target access network device.

[0369] The first information is transmitted via the Uu interface. In one possible implementation, the first information is carried in a newly added field of an existing message; for example, the first information is carried in the Packet Convergence Protocol Interval Sequence Number Status Report (PDCP SN GAP). In another possible implementation, the first information is carried in a newly added message; this embodiment of the application does not limit this approach.

[0370] Optionally, before the terminal device sends the first information to the target access network device, the communication method provided in this application embodiment further includes:

[0371] The target access network device sends status feedback information to the terminal device. Correspondingly, the terminal device receives status feedback information from the target access network device.

[0372] The process of the terminal device sending first information to the target access network device includes: the terminal device sending first information to the target access network device based on status feedback information.

[0373] Specifically, after the terminal device connects to the target access network device, if it receives the PDCP SR status feedback for uplink data from the target access network device, the terminal device can determine whether there are any data packets that have been timed out and discarded by the terminal device in the PDCP SR (i.e., the uplink data packets that the target access network device wants the terminal device to retransmit) based on the feedback information indicated by the target access network device. If so, the terminal device will send back the PDCP SN GAP to indicate the uplink data packets that have been timed out and discarded by the terminal device, so as to avoid the target access network device waiting for invalid uplink data.

[0374] S1830, the target access network device receives data transmitted from the terminal device based on the first information.

[0375] The communication method provided in this application embodiment allows the terminal device to directly send data loss information to the target access network device after the terminal device switches from the source access network device to the target access network device, instructing the terminal device to transmit data to the source access network device. Consequently, the target access network device can stop waiting for the lost data based on the first information.

[0376] The above mainly describes the solutions provided by the embodiments of this application from the perspective of the interaction between the source access network device, the target access network device, and the terminal device. Correspondingly, the embodiments of this application also provide a communication device for implementing the various methods described above. This communication device can be the source access network device in the above method embodiments, or a device containing the source access network device, or a component usable in the source access network device; or, the communication device can be the target access network device in the above method embodiments, or a device containing the target access network device, or a component usable in the target access network device; or, the communication device can be the terminal device in the above method embodiments, or a device containing the terminal device, or a component usable in the terminal device. It is understood that, in order to achieve the above functions, the communication device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Skilled professionals may 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.

[0377] For example, Figure 19 is a schematic diagram of a communication device provided in an embodiment of this application, wherein the communication device includes a transceiver module 1910 and a processing module 1920. The transceiver module 1910, also known as a transceiver unit, is used to implement the transceiver function, and may be a transceiver circuit, transceiver, transceiver device, or communication interface.

[0378] Taking the communication device as an example, which is the source access network device in the above method embodiment (which may be a chip of the source access network device, a module of the source access network device, or an internal device of the source access network device):

[0379] In this embodiment of the application, the processing module 1920 is used to determine the first information.

[0380] In this embodiment of the application, the transceiver module 1910 is used to send first information to the target access network device.

[0381] The first information is used to indicate the data discard information transmitted by the source access network device to the terminal device.

[0382] In one possible implementation, the first information is transmitted via the Xn-C interface. In another possible implementation, the first information is carried in a newly added field of the SN STATUS TRANSFER message. In yet another possible implementation, the first information is carried in a newly added field of the EARLY STATUS TRANSFER message.

[0383] In one possible implementation, the first information is carried in a newly added message.

[0384] In one possible implementation, the first information includes one or more of the following: loss status information of at least one business data unit, or the sequence number or COUNT value encoding of the first lost data.

[0385] In one possible implementation, the first information is transmitted via the Xn-U interface. In another possible implementation, the first information is carried in an extended sub-header added to the GTP-U tunnel.

[0386] In one possible implementation, the data discard information indicated by the first information is data packet-level discard information.

[0387] In one possible implementation, the first information includes one or more of the following: data type, PDU type, sequence number or COUNT value of the data discarded by the source access network device, or loss status information of at least one service data unit.

[0388] In another possible implementation, the data discard information indicated by the first information is discard information at the Protocol Data Unit Set (PDU Set) granularity.

[0389] In one possible implementation, the first information includes one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0390] In one possible implementation, the transceiver module 1910 is also used to send second information to the target access network device.

[0391] In this embodiment of the application, the second information is used to indicate the remaining delay of the data transmitted by the source access network device to the target access network device.

[0392] In one possible implementation, the second information is transmitted via the Xn-U interface. In another possible implementation, the second information is carried in a newly added field of the GTP-U tunnel extension header. In yet another possible implementation, the second information is carried in a newly added extension header of the GTP-U tunnel.

[0393] In one possible implementation, the remaining delay of the data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the data packet granularity.

[0394] In one possible implementation, the remaining delay of the data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the PDU Set granularity.

[0395] In one possible implementation, the transceiver module 1910 is further configured to send third information to the target access network device, the third information being used to indicate the redundancy ratio of the PDU Set transmitted by the source access network device to the target access network device.

[0396] In one possible implementation, the third information is transmitted via the Xn-U interface. In another possible implementation, the third information is carried in a newly added field of the GTP-U tunnel extension subheader. In yet another possible implementation, the third information is transmitted via the Xn-C interface.

[0397] In one possible implementation, the third information includes one or more of the following: PDU type, or the redundancy ratio of the PDU Set.

[0398] In one possible implementation, the transceiver module 1910 is further configured to send fourth information to the target access network device, the fourth information being used to indicate whether the data transmitted by the source access network device to the target access network device supports blind retransmission.

[0399] In one possible implementation, the fourth information is transmitted via the Xn-U interface. In another possible implementation, the fourth information is carried in a newly added field of the GTP-U tunnel extension header. In yet another possible implementation, the fourth information is carried in a newly added extension header of the GTP-U tunnel.

[0400] In one possible implementation, the granularity of whether the data transmitted from the source access network device to the target access network device, as indicated by the fourth information, supports blind retransmission is at the data packet granularity.

[0401] In one possible implementation, the transceiver module 1910 is further configured to send fifth information to the target access network device, the fifth information being used to indicate the blind retransmission conditions for data transmitted by the source access network device to the target access network device.

[0402] In one possible implementation, the fifth piece of information is transmitted via the Xn-C interface.

[0403] In one possible implementation, the fifth piece of information includes one or more of the following: a remaining delay threshold, or an importance threshold.

[0404] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0405] In this embodiment, the source access network device is presented in an integrated manner, divided into various functional modules. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0406] For example, the processor 401 in the communication device 400 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to make the communication device 400 execute the communication method in the above method embodiment.

[0407] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0408] Taking the communication device as an example, which is the target access network device in the above method embodiment (which may be a chip of the target access network device, a module of the target access network device, or an internal device of the target access network device):

[0409] In this embodiment of the application, the transceiver module 1910 is used to receive first information from the source access network device.

[0410] In this embodiment of the application, the processing module 1920 is used to determine the first information.

[0411] In this embodiment of the application, the transceiver module 1910 is further configured to send the first information to the terminal device.

[0412] The first information is used to indicate the data loss information transmitted from the source access network device to the terminal device.

[0413] In one possible implementation, the first information is transmitted via the Xn-C interface. In another possible implementation, the first information is carried in a newly added field of the SN STATUS TRANSFER message. In yet another possible implementation, the first information is carried in a newly added field of the EARLY STATUS TRANSFER message.

[0414] In one possible implementation, the first information is carried in a newly added message.

[0415] In one possible implementation, the first information includes one or more of the following: loss status information of at least one business data unit, or the sequence number or COUNT value encoding of the first lost data.

[0416] In one possible implementation, the first information is transmitted via the Xn-U interface. In another possible implementation, the first information is carried in an extended sub-header added to the GTP-U tunnel.

[0417] In one possible implementation, the data discard information indicated by the first information is data packet-level discard information.

[0418] In one possible implementation, the first information includes one or more of the following: data type, PDU type, sequence number or COUNT value of the data discarded by the source access network device, or loss status information of at least one service data unit.

[0419] In one possible implementation, the data discard information indicated by the first information is discard information at the Protocol Data Unit Set (PDU Set) granularity.

[0420] In one possible implementation, the first information includes one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0421] In one possible implementation, the transceiver module 1910 is further configured to receive second information from the source access network device, the second information being used to indicate the remaining delay of data transmitted by the source access network device to the target access network device; the processing module 1920 is further configured to control the transceiver module 1910 to transmit data to the terminal device according to the remaining delay.

[0422] In one possible implementation, the second information is transmitted via the Xn-U interface. In another possible implementation, the second information is carried in a newly added field of the GTP-U tunnel extension header. In yet another possible implementation, the second information is carried in a newly added extension header of the GTP-U tunnel.

[0423] In one possible implementation, the remaining delay of the data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the data packet granularity.

[0424] In one possible implementation, the remaining delay of the data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the PDU Set granularity.

[0425] In one possible implementation, the transceiver module 1910 is further configured to receive third information from the source access network device, the third information being used to indicate the redundancy ratio of the PDU Set transmitted by the source access network device to the target access network device; the processing module 1920 is further configured to control the transceiver module 1910 to transmit the PDU Set to the terminal device according to the redundancy ratio.

[0426] In one possible implementation, the third information is transmitted via the Xn-U interface. In another possible implementation, the third information is transmitted via the Xn-C interface.

[0427] In one possible implementation, the third information includes one or more of the following: PDU type, or the redundancy ratio of the PDU Set.

[0428] In one possible implementation, the transceiver module 1910 is further configured to receive fourth information from the source access network device, the fourth information being used to indicate whether the data transmitted by the source access network device to the target access network device supports blind retransmission; the processing module 1920 is configured to control the transceiver module 1910 to retransmit data to the terminal device according to the fourth information.

[0429] In one possible implementation, the fourth information is transmitted via the Xn-U interface. In another possible implementation, the fourth information is carried in a newly added field of the GTP-U tunnel extension subheader.

[0430] In one possible implementation, the granularity of whether the data transmitted from the source access network device to the target access network device, as indicated by the fourth information, supports blind retransmission is at the data packet granularity.

[0431] In one possible implementation, the transceiver module 1910 is further configured to receive fifth information from the source access network device, the fifth information being used to indicate blind retransmission conditions for data transmitted by the source access network device to the target access network device; the processing module 1920 is further configured to control the transceiver module 1910 to receive retransmitted data from the source access network device according to the fifth information.

[0432] In one possible implementation, the fifth piece of information is transmitted via the Xn-C interface.

[0433] In one possible implementation, the fifth piece of information includes one or more of the following: a remaining delay threshold, or an importance threshold.

[0434] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0435] In this embodiment, the first communication node is presented as an integrated functional module. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0436] For example, the processor 401 in the communication device 400 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to make the communication device 400 execute the sensing method in the above method embodiment.

[0437] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0438] Taking the communication device as an example, which is the source access network device in the above method embodiment (which may be a chip of the source access network device, a module of the source access network device, or an internal device of the source access network device):

[0439] In this embodiment of the application, the transceiver module 1910 is used to receive first information from the terminal device, the first information being used to indicate data discard information transmitted by the terminal device to the source access network device;

[0440] In this embodiment of the application, the processing module 1920 is used to determine the first information.

[0441] In this embodiment of the application, the transceiver module 1910 is further configured to send the first information to the target access network device.

[0442] In one possible implementation, the transceiver module 1910 is further configured to send the first information to the target access network device, including: the transceiver module 1910 is further configured to send the first information to the target access network device via the Xn-C interface.

[0443] In one possible implementation, the first information is carried in a newly added field of the SN STATUS TRANSFER message. In another possible implementation, the first information is carried in a newly added field of the EARLY STATUS TRANSFER message.

[0444] In one possible implementation, the first information is carried in a newly added message.

[0445] In one possible implementation, the first information includes one or more of the following: loss status information of at least one business data unit, or the sequence number or COUNT value encoding of the first lost data.

[0446] In one possible implementation, the transceiver module 1910 is further configured to send the first information to the target access network device, including: the transceiver module 1910 is further configured to send the first information to the target access network device via the Xn-U interface.

[0447] In one possible implementation, the first information is carried in the newly added extended subheader of the GTP-U tunnel.

[0448] In one possible implementation, the data discard information indicated by the first information is data packet-level discard information.

[0449] In one possible implementation, the first information includes one or more of the following: data type, PDU type, sequence number or COUNT value of the data discarded by the terminal device, or loss status information of at least one business data unit.

[0450] In one possible implementation, the data discard information indicated by the first information is discard information at the PDU Set granularity.

[0451] In one possible implementation, the first information includes one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0452] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0453] In this embodiment, the first communication node is presented as an integrated functional module. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0454] For example, the processor 401 in the communication device 400 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to make the communication device 400 execute the sensing method in the above method embodiment.

[0455] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0456] Taking the communication device as an example, which is the target access network device in the above method embodiment (which may be a chip of the target access network device, a module of the target access network device, or an internal device of the target access network device):

[0457] In this embodiment of the application, the transceiver module 1910 is used to receive first information from the source access network device, the first information being used to indicate data loss information transmitted by the terminal device to the source access network device;

[0458] In this embodiment of the application, the processing module 1920 is used to determine the first information.

[0459] In this embodiment of the application, the transceiver module 1910 is further configured to receive data from the terminal device based on the first information.

[0460] In one possible implementation, the transceiver module 1910 is further configured to receive data from the terminal device according to the first information, including: the transceiver module 1910 is further configured to receive the first information from the source access network device through the Xn-C interface.

[0461] In one possible implementation, the first information is carried in a newly added field of the SN STATUS TRANSFER message. In another possible implementation, the first information is carried in a newly added field of the EARLY STATUS TRANSFER message.

[0462] In one possible implementation, the first information is carried in a newly added message.

[0463] In one possible implementation, the first information includes one or more of the following: loss status information of at least one business data unit, or the sequence number or COUNT value encoding of the first lost data.

[0464] In one possible implementation, the transceiver module 1910 is further configured to receive data from the terminal device according to the first information, including: the transceiver module 1910 is further configured to receive the first information from the source access network device through the Xn-U interface.

[0465] In one possible implementation, the first information is carried in the newly added extended subheader of the GTP-U tunnel.

[0466] In one possible implementation, the data discard information indicated by the first information is data packet-level discard information.

[0467] In one possible implementation, the first information includes one or more of the following: data type, PDU type, sequence number or COUNT value of the data discarded by the terminal device, or loss status information of at least one business data unit.

[0468] In one possible implementation, the data discard information indicated by the first information is discard information at the PDU Set granularity.

[0469] In one possible implementation, the first information includes one or more of the following: PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

[0470] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0471] In this embodiment, the target access network device is presented as an integrated functional module. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0472] For example, the processor 401 in the communication device 400 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to make the communication device 400 execute the communication method in the above method embodiment.

[0473] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0474] Taking the communication device as an example, which is the terminal device in the above method embodiment (which may be a chip of the terminal device, a module of the terminal device, or an internal device of the terminal device):

[0475] In this embodiment of the application, the processing module 1920 is used to control the device to switch from the source access network device to the target access network device;

[0476] In this embodiment of the application, the transceiver module 1910 is used to send first information to the target access network device, the first information being used to indicate the discard information of data transmitted by the terminal device to the source access network device.

[0477] In one possible implementation, the first information is transmitted via the Uu interface.

[0478] In one possible implementation, the first information is carried in the Packet Convergence Protocol Interval Sequence Number Status Report (PDCP SN GAP).

[0479] In one possible implementation, before the transceiver module 1910 sends the first information to the target access network device, the transceiver module 1910 is further configured to receive status feedback information from the target access network device;

[0480] The transceiver module 1910 is also used to send first information to the target access network device, including:

[0481] The transceiver module 1910 is also used to send the first information to the target access network device based on the status feedback information.

[0482] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0483] In this embodiment, the terminal device is presented in an integrated manner, divided into various functional modules. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0484] For example, the processor 401 in the communication device 400 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to make the communication device 400 execute the communication method in the above method embodiment.

[0485] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0486] Taking the communication device as an example, which is the target access network device in the above method embodiment (which may be a chip of the target access network device, a module of the target access network device, or an internal device of the target access network device):

[0487] In this embodiment of the application, the transceiver module 1910 is used to receive first information from the terminal device, the first information indicating data loss information transmitted by the terminal device to the source access network device;

[0488] In this embodiment of the application, the processing module 1920 is used to determine the first information.

[0489] In this embodiment of the application, the transceiver module 1910 is further configured to receive data from the terminal device based on the first information.

[0490] In one possible implementation, the first information is transmitted via the Uu interface.

[0491] In one possible implementation, the first information is carried in the Packet Convergence Protocol Interval Sequence Number Status Report (PDCP SN GAP).

[0492] In one possible implementation, before the transceiver module 1910 receives the first information from the terminal device, the transceiver module 1910 is also used to send status feedback information to the terminal device.

[0493] Optionally, the communication device may further include a storage module 1930, which can be used to store instructions and / or data, and the processing module 1920 can read the instructions and / or data in the storage module 1930.

[0494] In this embodiment, the target access network device is presented as an integrated functional module. Here, "module" can refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs, integrated logic circuitry, and / or other devices that can provide the aforementioned functions. In a simplified embodiment, those skilled in the art will recognize that the communication device can take the form of the communication device 400 shown in FIG. 4.

[0495] For example, the processor 401 in the communication device 600 shown in Figure 4 can call the computer execution instructions stored in the memory 403 to cause the communication device 400 to execute the communication method in the above method embodiment.

[0496] Specifically, the functions / implementation processes of the transceiver module 1910 and processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403. Alternatively, the functions / implementation processes of the processing module 1920 in Figure 19 can be implemented by the processor 401 in the communication device 400 shown in Figure 4 calling computer execution instructions stored in the memory 403, and the functions / implementation processes of the transceiver module 1910 in Figure 19 can be implemented by the communication interface 404 in the communication device 400 shown in Figure 4.

[0497] It should be understood that one or more of the above modules or units can be implemented by software, hardware, or a combination of both. When any of the above modules or units are implemented by software, the software exists as computer program instructions and is stored in memory. The processor can be used to execute the program instructions and implement the above method flow. The processor can be built into a SoC (System-on-a-Chip) or ASIC, or it can be a separate semiconductor chip. In addition to the core that executes software instructions for computation or processing, the processor may further include necessary hardware accelerators, such as field-programmable gate arrays (FPGAs), PLDs (Programmable Logic Devices), or logic circuits that implement dedicated logic operations.

[0498] When the above modules or units are implemented in hardware, the hardware can be any one or any combination of a CPU, microprocessor, digital signal processing (DSP) chip, microcontroller unit (MCU), artificial intelligence processor, ASIC, SoC, FPGA, PLD, application-specific digital circuit, hardware accelerator, or non-integrated discrete device, which can run the necessary software or perform the above method flow independently of software.

[0499] Optionally, embodiments of this application also provide a communication device (e.g., the communication device may be a chip or a chip system), which includes a processor for implementing the methods in any of the above method embodiments. In one possible design, the communication device further includes a memory. The memory is used to store necessary program instructions and data, and the processor can call the program code stored in the memory to instruct the communication device to execute the methods in any of the above method embodiments. Of course, the memory may not be included in the communication device. When the communication device is a chip system, it may be composed of chips or may include chips and other discrete devices; embodiments of this application do not specifically limit this.

[0500] Optionally, embodiments of this application also provide a computer-readable storage medium storing a computer program or instructions that, when run on a communication device, enable the communication device to execute the methods described in any of the above method embodiments or any implementation thereof.

[0501] Optionally, embodiments of this application also provide a communication system, which includes the communication device described in the above method embodiments.

[0502] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software programs, implementation can be, in whole or in part, in the form of a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another 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 can be any available medium accessible to a computer or a data storage device containing one or more servers, data centers, etc., that can be integrated with the medium. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state disks, SSDs).

[0503] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, the disclosure, and the appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0504] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the scope of this application. Accordingly, this specification and drawings are merely illustrative descriptions of the application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of the claims and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A communication method characterized by comprising: include: The source access network device sends first information to the target access network device, the first information being used to indicate the discard information of downlink DL data transmitted by the source access network device to the terminal device.

2. The method of claim 1, wherein, The first information is carried in the sequence status transmission SN STATUS TRANSFER message.

3. The method of claim 1, wherein, The first information is carried in the EARLY STATUS TRANSFER message.

4. The method according to any one of claims 1 to 3, characterized in that, The first information includes one or more of the following: Information on the discard status of DL data, or the sequence number or COUNT value of the first lost DL data.

5. The method of claim 4, wherein, The discard status information of the DL data uses a bitmap to indicate whether the DL data has been discarded.

6. The method of claim 1, wherein, The first information indicates that the discard information of the DL data is discard information at the Protocol Data Unit Set (PDU Set) granularity.

7. The method of claim 6, wherein, The first information includes one or more of the following: The PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: The source access network device sends a second message to the target access network device, the second message being used to indicate the remaining delay of the DL data transmitted by the source access network device to the target access network device.

9. The method of claim 8, wherein, The remaining delay of the DL data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the PDU Set granularity.

10. The method according to any one of claims 1 to 9, characterized in that, The method further includes: the source access network device sending third information to the target access network device, the third information being used to indicate the redundancy ratio of the PDU Set transmitted by the source access network device to the target access network device.

11. The method according to any one of claims 1 to 10, characterized in that, The method further includes: The source access network device sends a fourth message to the target access network device, the fourth message being used to indicate whether the data transmitted by the source access network device to the target access network device supports blind retransmission.

12. The method according to any one of claims 1 to 11, characterized in that, The method further includes: The source access network device sends a fifth message to the target access network device, the fifth message being used to indicate the blind retransmission conditions for the DL data transmitted by the source access network device to the target access network device.

13. The method of claim 12, wherein, The fifth piece of information includes one or more of the following: a remaining delay threshold, or an importance threshold.

14. A communication method, comprising: include: The target access network device receives first information from the source access network device, the first information being used to indicate the discard information of downlink DL data transmitted by the source access network device to the terminal device; The target access network device sends the first information to the terminal device.

15. The method of claim 14, wherein, The first information is carried in a new field of the Sequence Status Transmission (SN STATUS TRANSFER) message.

16. The method of claim 14, wherein, The first information is carried in a new field of the EARLY STATUS TRANSFER message.

17. The method according to any one of claims 14 to 16, characterized in that, The first information includes one or more of the following: Information on the discard status of DL data, or the sequence number or COUNT value of the first lost DL data.

18. The method of claim 17, wherein, The discard status information of the DL data uses a bitmap to indicate whether the DL data has been discarded.

19. The method of claim 14, wherein, The first information indicates that the discard information of the DL data is discard information at the Protocol Data Unit Set (PDU Set) granularity.

20. The method of claim 19, wherein, The first information includes one or more of the following: The PDU type, the number of the lost PDU Set, or the sequence number or COUNT value of the lost PDU in the PDU Set.

21. The method according to any one of claims 14 to 20, characterized in that, The method further includes: The target access network device receives second information from the source access network device, the second information being used to indicate the remaining delay of the DL data transmitted by the source access network device to the target access network device; The target access network device transmits DL data to the terminal device based on the remaining delay.

22. The method of claim 21, wherein, The remaining delay of the DL data transmitted from the source access network device to the target access network device, as indicated by the second information, is at the PDU Set granularity.

23. The method of any one of claims 14 to 22, wherein, The method further includes: The target access network device receives third information from the source access network device, the third information being used to indicate the redundancy ratio of the PDU Set transmitted by the source access network device to the target access network device; The target access network device transmits the PDU Set to the terminal device according to the redundancy ratio.

24. The method of claim 23, wherein, The third information includes one or more of the following: PDU type, or redundancy ratio of PDU Set.

25. The method of any one of claims 14 to 24, wherein, The method further includes: The target access network device receives fourth information from the source access network device, the fourth information being used to indicate whether the DL data transmitted by the source access network device to the target access network device supports blind retransmission; The target access network device retransmits DL data to the terminal device based on the fourth information.

26. The method of any one of claims 14 to 25, wherein, The method further includes: The target access network device receives fifth information from the source access network device, the fifth information being used to indicate the blind retransmission conditions for the DL data transmitted by the source access network device to the target access network device; The target access network device retransmits data to the terminal device based on the fifth piece of information.

27. The method of claim 26, wherein, The fifth piece of information includes one or more of the following: a remaining delay threshold, or an importance threshold.

28. A method of communication, comprising: include: The source access network device receives first information from the terminal device, the first information being used to indicate the discard information of the uplink UL data transmitted by the terminal device to the source access network device; The source access network device sends the first information to the target access network device.

29. A method of communication, comprising: include: The target access network device receives first information from the source access network device, the first information being used to indicate the discard information of uplink UL data transmitted by the terminal device to the source access network device; The target access network device receives UL data from the terminal device based on the first information.

30. A method of communication, comprising: include: The terminal device switches from the source access network device to the target access network device; The terminal device sends first information to the target access network device, the first information being used to indicate the discard information of uplink UL data transmitted by the terminal device to the source access network device.

31. A method of communication, comprising: include: The target access network device receives first information from the terminal device, the first information indicating the discard information of uplink UL data transmitted by the terminal device to the source access network device; The target access network device receives UL data from the terminal device based on the first information.

32. A communications device, characterized by The communication device includes a module for performing the method according to any one of claims 1 to 13, or includes a module for performing the method according to any one of claims 14 to 27; or, the communication device includes a module for performing the method according to claim 28, or includes a module for performing the method according to claim 29; or, the communication device includes a module for performing the method according to claim 30, or includes a module for performing the method according to claim 31.

33. A communications device, characterized by The communication device includes a processor; the processor is configured to perform the method according to any one of claims 1 to 13, or to cause the communication device to perform the method according to any one of claims 14 to 27; or, the processor is configured to perform the method according to claim 28, or to cause the communication device to perform the method according to claim 29; or, the processor is configured to perform the method according to claim 30, or to cause the communication device to perform the method according to claim 31.

34. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes instructions that, when executed, cause the method according to any one of claims 1 to 13 to be implemented, or cause the method according to any one of claims 14 to 27 to be implemented; or cause the method according to claim 28 to be implemented, or cause the method according to claim 29 to be implemented; or cause the method according to claim 30 to be implemented, or cause the method according to claim 31 to be implemented.

35. A computer program product, characterised in that, The computer program product includes instructions that, when executed, cause the method according to any one of claims 1 to 13 to be implemented, or cause the method according to any one of claims 14 to 27 to be implemented; or, the computer program product includes instructions that, when executed, cause the method according to claim 28 to be implemented, or cause the method according to claim 29 to be implemented; or, the computer program product includes instructions that, when executed, cause the method according to claim 30 to be implemented, or cause the method according to claim 31 to be implemented.

36. A communication system, characterized by The communication system includes the communication device as described in claims 32 and 33.

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