A communication method and apparatus

Abstract

This application discloses a communication method and apparatus, enabling an access network device to determine the PDCP SN of a PDCP PDU in a second data packet based on the first SN in a first data packet from a core network device. When different access network devices determine their respective PDCP SNs based on the first SN in the first data packet, the PDCP SNs determined by different access network devices for data packets with the same first SN from the core network device are consistent. Thus, when a UE switches between different access network devices, the transmission progress of MBS services between the two access network devices can be determined based on the transmission status of the PDCP SNs of the different access network devices, and further, the loss of MBS service data packets can be avoided through a data forwarding mechanism, ensuring the continuity of MBS service transmission.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] Multimedia broadcast multicast service (MBMS) in LTE systems or multicast broadcast service (MBS) in new radio (NR) systems are mainly applicable to services that target multiple terminal devices, such as live broadcasts and scheduled program playback.

[0003] Currently, MBS services are transmitted from the core network to access network equipment (such as base stations) through a shared MBS session. One MBS session corresponds to one transmission channel (e.g., a General Packet Radio Service (GPRS) tunneling protocol-user plane (GTP-U) tunnel or an N3 interface), and one MBS session can contain one or more Quality of Service (QoS) flows.

[0004] On the access network equipment side, the access network equipment can determine the mapping relationship between QoS flows and data radio bearers (DRBs), thereby mapping one or more QoS flows to the same DRB for transmission. Specifically, after the data packets in the QoS flow are processed by the PDCP layer in the DRB, they become PDCP PDUs. Each PDCP PDU carries a PDCP SN, and different data packets carry different PDCP SNs.

[0005] Under the current MBS transmission mechanism, different access network devices transmit MBS services independently. When a UE moves between different access network devices, packet loss may occur due to the inconsistent MBS service transmission progress of the two access network devices, which cannot guarantee the continuity of MBS service transmission. Summary of the Invention

[0006] This application provides a communication method and apparatus for ensuring that the PDCP SN of the same data packet of MBS service transmitted by different access network devices is the same, so as to improve the continuity of MBS service transmission.

[0007] In a first aspect, embodiments of this application provide a communication method, which can be executed by a first access network device or a component (such as a processor, chip, or chip system) within the first access network device. The first access network device supports MBS data transmission. For example, the first access network device is a source base station or a target base station in a UE handover scenario.

[0008] According to this method, a first access network device can receive a first data packet of a first session from a core network device, the first data packet including a first SN. The first access network device can also send a second data packet to a terminal device, the second data packet being data belonging to a first DRB (or, the second data packet belonging to the first DRB), the second data packet including a PDCP PDU, the PDCP PDU being obtained based on the first data packet, and the PDCP SN of the PDCP PDU being determined based on the first SN.

[0009] Using the above method, access network devices can determine the PDCP SN of the PDCP PDU corresponding to the first data packet based on the first SN in the first data packet. When different access network devices determine their respective PDCP SNs based on the first SN in the first data packet, the PDCP SNs determined by different access network devices for data packets with the same first SN from the core network device are consistent. Thus, when a UE switches between different access network devices, the transmission progress of MBS services between the two access network devices can be determined based on the transmission status of the PDCP SNs of the different access network devices. Furthermore, the data forwarding mechanism can be used to avoid the loss of MBS service data packets, ensuring the continuity of MBS service transmission. Ensuring the continuity of MBS service transmission requires minimizing packet loss.

[0010] In one possible example, the first session has a one-to-one mapping relationship with the first DRB, and the first SN is a GTP-U SN.

[0011] With this design, when there is a one-to-one mapping relationship between the first session to which the first data packet belongs and the first DRB, the access network device determines the PDCP SN corresponding to the first data packet based on the GTP-U SN of the first data packet, so as to keep the PDCP SN of the same data packet determined by different access network devices consistent.

[0012] In one possible design, the first data packet belongs to a data packet of a first QoS flow, wherein the first QoS flow belongs to one of at least one QoS flow included in the first session, the second data packet belongs to a data packet of a first DRB, the first QoS flow and the first DRB have a one-to-one mapping relationship, and the first SN is a QFI SN.

[0013] With this design, when there is a one-to-one mapping relationship between the QoS flow to which the first data packet belongs and the first DRB, the access network device determines the PDCP SN corresponding to the first data packet based on the QFISN of the first data packet, so as to keep the PDCP SN of the same data packet determined by different access network devices consistent.

[0014] In one possible design, a first message is sent to the core network device, indicating a mapping relationship between at least one QoS flow included in a first session and at least one DRB, the at least one DRB including the first DRB.

[0015] With this design, the first access network device can report the mapping relationship between the MBS session or the QoS flow in the MBS session and the DRB to the core network device. The core network device then sets the first SN in the first data packet according to the mapping relationship, so that different access network devices can obtain the same PDCP SN when determining the PDCP SN based on the first SN in the first data packet.

[0016] In one possible design, the first information indicates the mapping relationship between each of the at least one DRB and at least one or more QoS flows in the at least one QoS flow.

[0017] With this design, the first access network device can report the mapping relationship between the MBS session or the QoS flow in the MBS session and the DRB to the core network device. The core network device then sets the first SN in the first data packet according to the mapping relationship, so that different access network devices can obtain the same PDCP SN when determining the PDCP SN based on the first SN in the first data packet.

[0018] In one possible design, the first data packet belongs to a first session, and the first DRB corresponds to some or all of the QoS flows in at least one QoS flow contained in the first session; the first SN includes a first GTP-USN SN, and the first PDCP SN is N0. The first access network device can also receive at least one third data packet from the core network device, and the at least one third data packet is mapped to the first DRB. The GTP-USN contained in the at least one third data packet is greater than the first GTP-USN. The first access network device can also determine that the PDCP SN corresponding to the i-th third data packet after being sorted in a first order is N0+i, where the first order includes the ascending order of the GTP-USN contained in the at least one third data packet, and i is an integer greater than or equal to 0.

[0019] With this design, the first access network device can receive at least one third data packet from the core network device. The PDCP SN corresponding to each third data packet can be determined based on the size of the GTP-U SN of the third data packet, the size of the GTP-U SN of the first data packet, and the size of the PDCP SN corresponding to the first data packet, so that the PDCP SN corresponding to the same data packet determined by different access network devices is the same.

[0020] In one possible design, the first access network device may also send second information to the second access network device, the second information indicating a correspondence between at least one PDCP SN and at least one GTP-U SN, the correspondence including at least one of the following: the correspondence between N0 and the first GTP-U SN; or, the correspondence between N0+i and the i-th GTP-U SN of the at least one third data packet ordered in a first order; or, the correspondence between N0+1+1 and M+1, where I is the number of third data packets and M is the GTP-U SN of the i-th third data packet of the at least one third data packet ordered in a first order.

[0021] This design ensures that when the first access network device and the second access network device start transmitting MBS service data one after the other, the PDCP SN of the same data packets determined by the first access network device and the second access network device remains consistent.

[0022] In one possible design, the first access network device can receive the PDCP SN corresponding to the first SN, and the PDCP SN of the PDCPPDU includes the PDCP SN corresponding to the first SN.

[0023] Using this design, the first access network device can determine the PDCP SN corresponding to the first data packet based on instructions from other access network devices or core network devices, thus maintaining consistency in the PDCP SNs determined by different access network devices. For example, when the second access network device starts MBS service data transmission before the first access network device, the second access network device can send the correspondence between the PDCP SN and the GTP-U SN of the first data packet it has determined to the first access network device. When the first access network device receives the first data packet, it can modify the correspondence to determine the PDCP SN corresponding to the first data packet.

[0024] In one possible design, the first SN also includes a QFI SN, and the first access network device can also determine the PDCP SN of the data packet with the smallest GTP-USN after the consecutively lost data packets in all QoS flows corresponding to the first DRB.

[0025] This design can prevent the PDCP SN determined by the first access network device from being different from that of other access network devices when packet loss occurs in the data packets sent from the core network device to the first access network device.

[0026] Secondly, embodiments of this application provide a communication method that can be executed by a core network device or a component (such as a processor, chip, or chip system) within the core network device.

[0027] According to this method, the core network device can receive first information from the first access network device, which indicates the mapping relationship between at least one QoS flow and at least one DRB included in the first session. The core network device can also sequentially set the first SN of data packets in at least one QoS flow corresponding to the first DRB in ascending order of GTP-USN, where the at least one DRB includes the first DRB, and the data packets in the QoS flow corresponding to the first DRB include the first data packet of the first session. The core network device can also send the first data packet to the first access network device through the first QoS flow in the first session, where the first QoS flow is one of the at least one QoS flow in the first session corresponding to the first DRB.

[0028] The first information can be found in the description of the first aspect and its possible designs.

[0029] The beneficial effects described in the second aspect above can be found in the beneficial effects described in the first aspect above.

[0030] Thirdly, embodiments of this application provide a communication device that can implement the method described in the first aspect above or any possible design by a first access network device. The device includes corresponding units or components for performing the described method. The units included in the device can be implemented in software and / or hardware. The device can be, for example, a first access network device, or a component, baseband chip, chip system, or processor that supports the implementation of the described method in the first access network device.

[0031] For example, the communication device may include modular components such as a transceiver unit (or communication module, transceiver module) and a processing unit (or processing module), which can perform the corresponding functions of the first access network device in the first aspect described above or any possible design thereof. When the communication device is a first access network device, the transceiver unit may be a transmitter and a receiver, or a transceiver obtained by integrating a transmitter and a receiver. The transceiver unit may include an antenna and radio frequency circuits, etc., and the processing unit may be a processor, such as a baseband chip. When the communication device is a component having the functions of the first access network device described above, the transceiver unit may be a radio frequency unit, and the processing unit may be a processor. When the communication device is a chip system, the transceiver unit may be the input / output interface of the chip system, and the processing unit may be the processor of the chip system, such as a central processing unit (CPU).

[0032] The transceiver unit can be used to perform the receiving and / or transmitting actions performed by the first access network device in the first aspect or any possible design thereof. The processing unit can be used to perform actions other than receiving and transmitting performed by the first access network device in the first aspect or any possible design thereof, such as determining the PDCP SN corresponding to the first data packet based on the first SN.

[0033] Fourthly, embodiments of this application provide a communication device that can implement the method described in the second aspect above or any possible design by a core network device. The device includes corresponding units or components for performing the described method. The units included in the device can be implemented in software and / or hardware. The device can be, for example, a core network device, or a component, baseband chip, chip system, or processor that supports the implementation of the described method within the core network device.

[0034] For example, the communication device may include modular components such as a transceiver unit (or communication module, transceiver module) and a processing unit (or processing module), which can perform the corresponding functions of the core network equipment in the second aspect above or any possible design. When the communication device is a core network equipment, the transceiver unit may be a transmitter and a receiver, or a transceiver obtained by integrating a transmitter and a receiver. The transceiver unit may include an antenna and radio frequency circuits, etc., and the processing unit may be a processor, such as a baseband chip. When the communication device is a component with the functions of the core network equipment described above, the transceiver unit may be a radio frequency unit, and the processing unit may be a processor. When the communication device is a chip system, the transceiver unit may be the input / output interface of the chip system, and the processing unit may be the processor of the chip system, such as a central processing unit (CPU).

[0035] The transceiver unit can be used to perform the receiving and / or transmitting actions performed by the core network equipment in the second aspect or any possible design thereof. The processing unit can be used to perform actions other than receiving and transmitting performed by the core network equipment in the second aspect or any possible design thereof.

[0036] Fifthly, a communication system is provided, which includes the communication devices shown in the third and fourth aspects.

[0037] A sixth aspect provides a computer-readable storage medium for storing computer instructions that, when executed on a computer, cause the computer to perform the methods shown in the first to second aspects or any possible implementation thereof.

[0038] In a seventh aspect, a computer program product comprising instructions that, when executed on a computer, cause the computer to perform the methods shown in the first to second aspects or any possible implementation thereof.

[0039] Eighthly, a circuit is provided coupled to a memory, the circuit being used to perform the methods shown in the first to second aspects or any possible embodiments thereof. The circuit may include a chip circuit. Attached Figure Description

[0040] Figure 1 This application provides a schematic diagram of the architecture of a communication system.

[0041] Figure 2 A schematic diagram illustrating the MBS service data forwarding method of access network equipment;

[0042] Figure 3 This is a schematic diagram of a communication protocol stack architecture;

[0043] Figure 4 This is a schematic diagram of the architecture of another communication system provided in an embodiment of this application;

[0044] Figure 5 This is a schematic diagram of a UE handover process;

[0045] Figure 6 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0046] Figure 7 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0047] Figure 8 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0048] Figure 9 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0049] Figure 10 A flowchart illustrating a communication method provided in an embodiment of this application;

[0050] Figure 11 This application provides a schematic diagram of an MBS service data forwarding method for an access network device.

[0051] Figure 12 A schematic diagram illustrating another MBS service data forwarding method for an access network device provided in this application embodiment;

[0052] Figure 13 This is a schematic diagram of another MBS service data forwarding method for an access network device provided in an embodiment of this application. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operating methods in the method embodiments can also be applied to the device embodiments or system embodiments.

[0054] like Figure 1 As shown, the communication method provided in this application embodiment can be applied to a wireless communication system, which may include a terminal device 101 and a network device 102.

[0055] It should be understood that the above wireless communication systems are applicable to both low-frequency (sub-6G) and high-frequency (above-6G) scenarios. Application scenarios for these wireless communication systems include, but are not limited to, fifth-generation systems, new radio (NR) communication systems, or future evolved public land mobile network (PLMN) systems.

[0056] The terminal device 101 shown above can be user equipment (UE), terminal, access terminal, terminal unit, terminal station, mobile station (MS), remote station, remote terminal, mobile terminal, wireless communication equipment, terminal agent, terminal equipment, cellular phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA) device, handheld device with wireless communication capabilities, computing device or other processing device connected to a wireless modem, vehicle-mounted device, wearable device, terminal device in a future 5G network, or terminal device in a future evolved PLMN network, etc. This terminal device 101 may have wireless transceiver capabilities, enabling it to communicate (e.g., wirelessly) with one or more network devices in one or more communication systems and receive network services provided by the network devices, including but not limited to the network device 102 shown in the figure.

[0057] Furthermore, terminal device 101 can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; terminal device 101 can also be deployed on water (such as on ships); terminal device 101 can also be deployed in the air (such as on airplanes, balloons, and satellites). Specifically, terminal device 101 can be a mobile phone, tablet, computer with wireless transceiver capabilities, virtual reality (VR) terminal, augmented reality (AR) terminal, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical care, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, etc. Terminal device 101 can also be a communication chip with a communication module, a vehicle with communication capabilities, or in-vehicle equipment (such as in-vehicle communication devices, in-vehicle communication chips), etc.

[0058] Network device 102 can be an access network device (or access point). Access network device refers to equipment that provides network access functionality, such as a radio access network (RAN) base station (or RAN equipment). Specifically, network device 102 may include a base station (BS), or a base station and radio resource management equipment used to control the base station. Network device 102 may also include relay stations (relay equipment), access points, and base stations in future 5G networks, base stations in future evolved PLMN networks, or NR base stations. Network device 102 can be a wearable device or an in-vehicle device. Network device 102 can also be a communication chip with a communication module.

[0059] For example, network equipment 102 includes, but is not limited to: next-generation base stations (g nodeB, gNB) in 5G, evolved node B (eNB) in long term evolution (LTE) systems, radio network controllers (RNCs), radio controllers in cloud radio access networks (CRAN) systems, base station controllers (BSCs), home base stations (e.g., home evolved nodeB, or home node B, HNB), baseband units (BBUs), transmitting and receiving points (TRPs), transmitting points (TPs), mobile switching centers, base transceiver stations (BTSs) in global system for mobile communication (GSM) or code division multiple access (CDMA) networks, and may also be node base stations in wideband code division multiple access (WCDMA) networks. It can be a station (NB), an evolved NB (eNB or eNodeB) in LTE, a base station in a future 5G network, an access network in a future evolved PLMN network, or a wearable device or vehicle-mounted device.

[0060] In some deployments, network devices may include centralized units (CUs) and distributed units (DUs). Network devices may also include active antenna units (AAUs). The CU implements some of the network device's functions, and the DU implements others. For example, the CU is responsible for handling non-real-time protocols and services, implementing radio resource control (RRC) and packet data convergence protocol (PDCP) layer functions. The DU is responsible for handling physical layer protocols and real-time services, implementing radio link control (RLC), media access control (MAC), and physical (PHY) layer functions. The AAU implements some physical layer processing functions, radio frequency processing, and active antenna-related functions. Since RRC layer information ultimately becomes PHY layer information, or is derived from PHY layer information, in this architecture, higher-layer signaling, such as RRC layer signaling, can also be considered as being sent by the DU, or by the DU+AAU. It is understood that network devices can be one or more of the following: CU nodes, DU nodes, and AAU nodes. Furthermore, a CU can be classified as a network device in the radio access network (RAN), or it can be classified as a network device in the core network (CN) (which may be referred to as a CN device); this application does not limit this classification.

[0061] Furthermore, network device 102 can connect to core network (CN) equipment, which can be used to provide core network services to terminal device 101 accessing network device 102. Core network equipment can correspond to different devices in different systems. For example, in 3G, core network equipment can correspond to a Serving GPRS Support Node (SGSN) and / or a Gateway GPRS Support Node (GGSN) for General Packet Radio Service (GPRS). In 4G, core network equipment can correspond to a Mobility Management Entity (MME) and / or a Serving Gateway (S-GW), etc. In 5G, core network equipment can correspond to an Access and Mobility Management Function (AMF) entity, a Session Management Function (SMF) entity, or a User Plane Function (UPF) entity, etc.

[0062] It should be understood that Figure 1 In addition, network device 102 can also be connected to at least one terminal device other than terminal device 101. Therefore, at least one terminal device, including terminal device 101, can receive MBS services through network device 102.

[0063] based on Figure 1 In the architecture shown, MBS services can be transmitted from the core network to network device 102 through a shared MBS session. One MBS session corresponds to one transmission channel (e.g., a GTP-U tunnel or N3 interface), and one MBS session can contain one or more QoS flows, which can also be called MBS flows. When the core network device sends data packets to the access network device, it carries a GTP-U sequence number (SN) and / or a QoS flow identifier (QFI) SN in the data packets. The GTP-U SNs of multiple data packets within the same MBS session are consecutive, and the QFI SNs of multiple data packets within the same QoS flow are consecutive.

[0064] like Figure 2As shown, an MBS session / GTP-U tunnel contains three QoS flows. Each data packet carries a GTP-U SN, and the GTP-U SN does not distinguish between QoS flows, increasing sequentially. Optionally, each data packet can also carry a QFI SN. The QFI SN is set independently for each QoS flow data packet; that is, for QoS flow A data packets, the QFI SN increases sequentially from the initial value, and the same applies to QoS flow B and QoS flow C data packets, also increasing sequentially from the initial value. The QFI SN settings for the three QoS flows are independent of each other.

[0065] Additionally, after receiving data packets through the N3 interface, network device 102 maps the MBS session or MBS flow within the MBS session to a DRB, thereby transmitting the data packets from the MBS session or QoS flow to the UE through the corresponding DRB. Each DRB corresponds to one PDCP entity; that is, each DRB's configuration contains the configuration of a PDCP entity. Figure 2 In the process of instructing MBS flow to be mapped to DRB, PDCP can be used instead of DRB. For example, data packets mapped to PDCP A will be transmitted to the UE using the corresponding DRB A, while data packets mapped to PDCP B will be transmitted to the UE using the corresponding DRB B.

[0066] exist Figure 2 In this example, assuming network device 102 maps QoS flow A and QoS flow C to PDCP A (DRB A), and maps QoS flow B to PDCP B (DRB B), then ultimately, data packets for QoS flow A and QoS flow C will be transmitted through DRB A, and data packets for QoS flow B will be transmitted through DRB B. Specifically, in each DRB's PDCP entity, a PDCP SN number needs to be added to the PDCP header of each data packet for the PDCP entity to process the data packets.

[0067] When network device 102 sends data to terminal device 101, network device 102 can send MBS service data to terminal device via point-to-multipoint (PTM) or point-to-point (PTP) transmission. Terminal device receives MBS service data in the corresponding manner. Terminal device here includes, but is not limited to, terminal device 101.

[0068] In this application, transmitting using PTM means that when a device transmits a transport block (TB) corresponding to a protocol data unit (PDU), it scrambles the PDU with a group radio network temporary identifier (G-RNTI) or scrambles the downlink control information (DCI) corresponding to the PDU, while one or more devices receive the same PDU based on the same G-RNTI; or transmitting a PDU using PTM means that the location of the same PDU is told to multiple devices in a semi-static manner, and multiple devices can receive the PDU simultaneously; or transmitting a PDU using PTM means that the PDU is transmitted in a DRB established for multicast transmission or in a channel specifically designed for multicast.

[0069] Receiving using PTM means that when transmitting using PTM transmission, one of the multiple receiving devices receives the PDU according to G-RNTI; or one of the multiple receiving devices receives the PDU through a DRB established for multicast transmission or on a channel used for multicast transmission.

[0070] It should be understood that in this application, multicast is a specific method of multicast, therefore, multicast can also be called multicast.

[0071] Transmitting using PTP means that when a device transmits the TB corresponding to a PDU, it scrambles the PDU with the cell network temporary identifier (C-RNTI) or the DCI corresponding to the PDU, and only one device receives the same PDU according to the C-RNTI at the same time; or transmitting a PDU using PTP means that the PDU is transmitted in a DRB established for unicast or in a channel specifically designed for unicast.

[0072] Receiving using PTP means that when transmitting using PTP, a receiving device receives the PDU according to the C-RNTI; or a device receives through a DRB established for unicast transmission or on a channel used for unicast transmission.

[0073] like Figure 1 The network devices and terminal devices shown can each have a certain protocol stack structure for mutual communication. Figure 3 This is a schematic diagram of the protocol stack structure of a network device and a terminal device. Figure 3In the diagram, the dashed line represents data being sent from the network device to the terminal device. This is merely illustrative; the direction of data transmission can also be from the terminal device to the network device. For example... Figure 3 As shown, for example, the control plane protocol stack structure may include the radio resource control (RRC) layer, the service data adaptation protocol (SDAP) layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, the media access link control (MAC) layer, and the physical layer. The physical layer is located at the lowest layer (layer one), the MAC layer, RLC layer, PDCP layer, and SDAP layer belong to the second layer (layer two), and the RRC layer belongs to the third layer (layer three).

[0074] MBS data first arrives at the PDCP layer of the network device. After processing by the PDCP layer, it is transmitted to the RLC and MAC layers. After further processing, it is sent out from the physical layer and transmitted to the terminal device via the air interface. Then, the various protocol layers on the terminal device side process the data packets sequentially in the reverse order of the network device's processing. The combined processing of data packets by each layer on both the network and terminal device sides is called a DRB. Each piece of data in the DRB needs to be processed by each layer, and each layer has a corresponding functional entity to perform its function, such as the PDCP entity in the PDCP layer.

[0075] Each DRB configuration contains a PDCP entity, and the DRB configuration is associated with at least one RLC entity, with each RLC entity corresponding to a logical channel. Above the PDCP, there may also be an SDAP layer, which is responsible for mapping data from the core network to different bearers.

[0076] Specific data examples are as follows: Before being transmitted at the physical layer, raw data needs to be processed by SDAP, PDCP, RLC, and MAC, and corresponding protocol layer headers need to be added. Of course, some layer headers are optional; for example, SDAP and RLC both have transmission methods without headers. Generally, PDCP PDUs, SDAP PDUs, and raw data packets correspond one-to-one. RLC may segment a PDCP data packet, while MAC may concatenate multiple RLC data packets.

[0077] like Figure 4 As shown in the embodiment of this application, in one scenario, the UE (such as...) Figure 4As shown, UE2 can be switched from the source gNB (SgNB) (or source gNB) to the target gNB (TgNB) (or target gNB) via handover.

[0078] In wireless communication systems, each cell covers only a limited area. Therefore, when a UE moves from its current serving cell to an adjacent cell, the network needs to switch the service to the adjacent cell to ensure service continuity and prevent interruption of communication. In short, handover refers to the process of switching the link carrying communication data from one cell (or access network device) to another cell (or access network device) during mobile communication to ensure uninterrupted communication.

[0079] by Figure 4 Taking the scenario shown below, where UE2 switches from SgNB (access network device #1) to TgNB (access network device #2), an exemplary handover process is illustrated. Figure 5 As shown in the example, the handover process in this example is initiated by the SgNB. The main steps include: the SgNB decides to hand over UE2 based on the measurement report reported by UE2 and sends a handover request to the TgNB. After receiving a positive handover response from the TgNB, the SgNB sends a handover command to UE2. Upon receiving the handover command, UE2 stops transmitting uplink or downlink data with the SgNB, begins synchronization with the TgNB, and initiates a random access procedure. When sending the handover command to UE2, the SgNB stops transmitting uplink or downlink data with UE2 and sends the data stored in the SgNB to the TgNB. After successfully accessing the TgNB, UE2 begins transmitting uplink or downlink data with the TgNB.

[0080] The specific process includes the following steps:

[0081] 1. During the handover preparation phase, UE2 in RRC connected state sends a measurement report according to the measurement reporting triggering criteria configured in SgNB.

[0082] 2. Based on UE2's measurement report and RRM algorithm, when UE2 meets the handover conditions, SgNB determines TgNB for UE2 and sends UE2's context information to TgNB along with the handover request.

[0083] 3. The TgNB prepares for the incoming UE2, assigning C-RNTI and other parameters to UE2, and returns this information to the SgNB in ​​the handover request confirmation message. Upon receiving the handover request confirmation message, the SgNB prepares to forward packet data to the TgNB.

[0084] 4. The SgNB sends a handover command to UE2 (the handover command includes the following information: new C-RNTI, TgNB's SIB, and UE2's configuration information, such as MAC, RLC, and PDCP layer configurations). After receiving the handover command, UE2 stops uplink or downlink data transmission with the SgNB and synchronizes with the TgNB.

[0085] At this point, the SgNB forwards the cached uplink data from UE2 and downlink data from UPF to the TgNB.

[0086] 5. SgNB sends SN status information to TgNB.

[0087] 6. After UE2 disconnects data transmission with the SgNB, it initiates a downlink synchronization procedure with the TgNB, and then initiates a random access procedure to obtain uplink timing and uplink resource allocation. The TgNB sends a TA to UE2 and indicates the resources allocated to it. This information will be used by UE2 to send an RRC connection reconfiguration complete message to the TgNB to indicate that the handover is complete.

[0088] 7. UE2 sends a "handover confirmation" message to TgNB, indicating that the handover is complete.

[0089] 8. The TgNB indicates to the SgNB that the handover is complete so that the SgNB can release the context information of UE2.

[0090] At the same time, the TgNB notifies the core network nodes to update the data forwarding destination gNB information so that the core network can send the data of UE2 to the TgNB.

[0091] based on Figure 5 As shown in the process, UE2 can switch from access network device #1 to access network device #2. However, since the PDCP SN of the MBS service data packets transmitted from the access network devices to the UE is determined by each access network device, even if access network device #1 and access network device #2 transmit the same MBS service data packets, the PDCP SNs set for the same MBS service data packets by access network device #1 and access network device #2 are different. Therefore, when UE2 switches from access network device #1 to access network device #2, it cannot continue to receive data packets after the PDCP SN of the data packets originally received in access network device #1, resulting in data packet loss or MBS service interruption.

[0092] To improve the continuity of MBS services during UE handover scenarios, embodiments of this application provide a communication method. This communication method can be applied to... Figure 1 or Figure 4The scenario is illustrated. This communication method can be implemented by access network equipment and / or core network equipment, wherein the access network equipment includes... Figure 1 Network device 102 shown Figure 4 At least one of the access network devices #1 or #2 shown, the core network device will soon... Figure 1 or Figure 4 The core network equipment shown.

[0093] The following section, with reference to the accompanying drawings, describes the possible structures of access network equipment and core network equipment.

[0094] For example, Figure 6 A schematic diagram of a possible structure for an access network device is shown, which may include a processing module 610 and a transceiver module 620. Exemplarily, Figure 6 The structure shown can be an access network device, or a chip or other combination of devices, components (or assemblies) with the functions of the access network device shown in this application, applied within the access network device. When the structure is an access network device, the transceiver module 620 may include a transceiver and / or a communication interface. The transceiver may include an antenna and radio frequency circuits, etc., and the communication interface, such as a fiber optic interface, can support wired communication between the access network device and the core network device. The processing module 610 may be a processor, such as a baseband processor, which may include one or more central processing units (CPUs). When the structure is a component with the functions of the access network device shown in this application, the transceiver module 620 may be a radio frequency unit, and the processing module 610 may be a processor, such as a baseband processor. When the structure is a chip system, the transceiver module 620 may be the input / output interface of a chip (such as a baseband chip), and the processing module 610 may be the processor of the chip system, which may include one or more central processing units. It should be understood that the processing module 610 in the embodiments of this application can be implemented by a processor or processor-related circuit components, and the transceiver module 620 can be implemented by a transceiver or transceiver-related circuit components.

[0095] For example, processing module 610 can be used to perform all operations performed by the access network device in any embodiment of this application, except for transmit / receive operations, such as processing operations, and / or other processes to support the technology described herein, such as generating messages, information, and / or signaling sent by transceiver module 620, and processing messages, information, and / or signaling received by transceiver module 620. Transceiver module 620 can be used to perform all receive and transmit operations performed by the access network device in any embodiment of this application, and / or other processes to support the technology described herein.

[0096] also, Figure 6The illustrated structure can also be used to implement a terminal device or a component within a terminal device. For example, the processing module 610 can be used to perform all operations performed by the terminal device in any embodiment of this application, except for the transmit and receive operations, such as processing operations, and / or other processes to support the technology described herein, such as generating messages, information, and / or signaling sent by the transceiver module 620, and processing messages, information, and / or signaling received by the transceiver module 620. The transceiver module 620 can be used to perform all receive and transmit operations performed by the terminal device in any embodiment of this application, and / or other processes to support the technology described herein.

[0097] Alternatively, the transceiver module 620 can be a single functional module capable of both transmitting and receiving operations. For instance, the transceiver module 620 can execute all transmitting and receiving operations performed by the access network device or terminal device. For example, when performing a transmitting operation, the transceiver module 620 can be considered a transmitting module, and when performing a receiving operation, it can be considered a receiving module. Alternatively, the transceiver module 620 can also be two functional modules, collectively referred to as the transmitting module and the receiving module. The transmitting module performs the transmitting operation; for example, it can execute all transmitting operations performed by the access network device or terminal device. The receiving module performs the receiving operation; it can execute all receiving operations performed by the access network device or terminal device.

[0098] Figure 7 A schematic diagram of another access network device is shown. For example... Figure 7 As shown, access network equipment includes structures such as a processor, memory, radio frequency (RF) unit (or RF circuit) or antenna. The processor is mainly used for processing communication protocols and data, controlling network devices, executing software programs, and processing software program data. The memory is mainly used to store software programs and data. The RF unit is mainly used for converting baseband signals to RF signals and processing RF signals.

[0099] like Figure 7 As shown, the access network device may include a transceiver module 710 and a processing module 720. The transceiver module may include a sending module and a receiving module; alternatively, the transceiver module 710 may be a single module capable of both sending and receiving functions. The transceiver module 710 can be connected to... Figure 6 The transceiver module 620 corresponds to the transceiver module 710, which can be used to implement the transceiver module 620; this processing module 720 can be connected with... Figure 6Corresponding to the processing module 610, the actions performed by the processing module 720 can be executed by the processing module 610. It should be understood that, as needed, the access network device may also include a communication interface for communicating with the core network device.

[0100] Optionally, the transceiver module 710 can also be referred to as a transceiver, transceiver circuit, or transceiver unit, etc., and may include at least one antenna and a radio frequency (RF) unit. The transceiver module 710 is mainly used for transmitting and receiving RF signals and converting RF signals to baseband signals. The processing module 710 is mainly used for baseband processing and controlling access network equipment, etc. The transceiver module 710 and the processing module 720 can be physically installed together or physically separated, i.e., in a distributed base station configuration.

[0101] For example, the transceiver module 710 may include one or more radio frequency units, such as a remote radio unit (RRU), and the processing module 720 may include one or more baseband units (BBU) (also referred to as digital units, DU).

[0102] In one example, the processing module 720 may consist of one or more single boards. These boards can collectively support a single access standard wireless access network (such as an LTE network), or they can each support different access standards wireless access networks (such as LTE, 5G, or other networks). The processing module 720 also includes a memory and a processor. The memory stores necessary instructions and data. The processor controls the access network device to perform necessary actions, such as controlling the access network device to execute the operation flow of the access network device in the embodiments shown in this application. The memory and processor can serve one or more single boards. That is, each single board can have its own memory and processor, or multiple single boards can share the same memory and processor. Furthermore, each single board can also have necessary circuitry.

[0103] also, Figure 7 The illustrated structure can also be used to implement a terminal device or a component within a terminal device. For example, the processing module 720 can be used to perform all operations performed by the terminal device in any embodiment of this application, except for the transmit and receive operations, such as processing operations, and / or other processes to support the technology described herein, such as generating messages, information, and / or signaling sent by the transceiver module 710, and processing messages, information, and / or signaling received by the transceiver module 710. The transceiver module 710 can be used to perform all receive and transmit operations performed by the terminal device in any embodiment of this application, and / or other processes to support the technology described herein.

[0104] Figure 8 This is a schematic diagram of the structure of a core network device provided in an embodiment of this application. The structure may include a processing module 810 and a transceiver module 820. Exemplarily, the structure may be the core network device shown, or it may be a chip or other combined device or component having the functions of the core network device shown in this application. When the structure is a core network device, the transceiver module 820 may be a communication interface, and the processing module 810 may be a processor, which may include one or more CPUs. When the structure is a component having the functions of the core network device shown in this application, the transceiver module 820 may be a communication interface, and the processing module 810 may be a CPU. When the structure is a chip system, the transceiver module 820 may be the input / output interface of a chip (e.g., a baseband chip), and the processing module 810 may be the processor of the chip system, which may include one or more central processing units. It should be understood that the processing module 810 in the embodiments of this application may be implemented by a processor or processor-related circuit components, and the transceiver module 820 may be implemented by a transceiver or transceiver-related circuit components.

[0105] For example, processing module 810 can be used to perform all operations performed by the core network device in this embodiment of the application, except for the transmit and receive operations, such as generating messages, information and / or signaling sent by transceiver module 820, and / or processing messages, information and / or signaling received by transceiver module 820, and / or other processes to support the technology described herein. Transceiver module 820 can be used to perform all transmit and / or receive operations performed by the core network device in this embodiment of the application, and / or other processes to support the technology described herein.

[0106] Figure 9 A schematic diagram of another communication device provided in an embodiment of this application is given, which can be implemented by hardware components. Figure 9 The device 900 shown may be a core network device, or a chip, chip system, or processor that supports the core network device in implementing the above methods. The device 900 may include modules, units, or means corresponding to the core network device executing the steps described in the embodiments of this application. These functions, units, or means may be implemented in software, hardware, or by hardware executing corresponding software, or a combination of software and hardware. Further details can be found in the corresponding descriptions in the following embodiments.

[0107] Taking a hardware implementation as an example, the device 900 may include one or more processors 901, which can also be called processing units, and can implement certain control functions. The processor 901 can be a general-purpose processor or a dedicated processor, for example, a baseband processor or a central processing unit. The baseband processor can be used to process communication protocols and communication data, while the central processing unit can be used to control communication devices (such as base stations, baseband chips, terminals, terminal chips, distribution units, or centralized units), execute software programs, and process data from the software programs.

[0108] In an alternative design, processor 901 may store instructions 903 and / or data that can be executed by the processor to cause device 900 to perform the methods described in the embodiments of this application.

[0109] In another alternative design, the processor 901 may include a transceiver unit for implementing receive and transmit functions. For example, this transceiver unit may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit can be used for reading and writing code / data, or it can be used for transmitting or relaying signals.

[0110] In another possible design, device 900 may include circuitry that performs the functions of sending, receiving, or communicating as described in the embodiments of this application.

[0111] Optionally, the device 900 may include one or more memories 902, which may store instructions 904 that can be executed on the processor, causing the device 900 to perform the methods described in the embodiments of this application. Optionally, the memory may also store data. Optionally, the processor may also store instructions and / or data. The processor and memory may be configured separately or integrated together. For example, the correspondence described in the embodiments of this application may be stored in memory or in the processor.

[0112] Optionally, the device 900 may further include a transceiver 905 and / or a communication interface 906. The processor 901, which may be referred to as a processing unit, controls the device 900. The transceiver 905, which may be referred to as a transceiver unit, transceiver, transceiver circuit, transceiver device, or transceiver module, is used to implement transceiver functions. The communication interface 906 may be a wireless transceiver, transceiver circuit, interface, or interface circuit.

[0113] The processor 901 can be used with Figure 8The processing module 810 corresponds to the processor 901, which can be implemented by the processor 901; the transceiver 905 and / or the communication interface 906 can be connected to... Figure 8 The transceiver module 820 in the above can be implemented by transceiver 905 and / or communication interface 906.

[0114] like Figure 10 As shown, the communication method provided in this application embodiment may include the following steps:

[0115] S101: The access network device receives a first data packet from the core network device for a first session, the first data packet including a first SN. The first session includes an MBS session.

[0116] It should be understood that the access network device here can be a first access network device and / or a second access network device. The first access network device may be, for example, the source base station of the UE in a UE handover scenario, and the second access network device may be, for example, the target base station in a UE handover scenario; or, the second access network device may be the source base station of the UE in a UE handover scenario, and the first access network device may be the target base station in a UE handover scenario.

[0117] This access network device, for example Figure 4 The access network device #1 and / or access network device #2 are shown. Core network devices, for example... Figure 4 The core network equipment shown is shown.

[0118] For example, the first data packet belongs to a first session (or first MBS session) between the access network device and the core network device, and the first session includes at least one QoS flow (or, the QoS flow may be replaced by an MBS flow).

[0119] For example, the first SN includes at least one of the GTP-U SN, QFI SN, or SN carried in the first data packet by a newly defined field in the packet header (e.g., MBS SN or other name).

[0120] S102: The access network device sends a second data packet to the terminal device. The second data packet belongs to the data packet of the first DRB. The second data packet includes a PDCP PDU. The PDCP PDU is obtained based on the first data packet, and the PDCPSN of the PDCP PDU is determined based on the first SN.

[0121] The second data packet can be a PDCP PDU. Generally, the first data packet transmitted from the core network device to the access network device serves as the PDCP SDU. After processing by the PDCP entity and adding a PDCP header, it becomes the second data packet, i.e., the PDCP PDU. Alternatively, the second data packet can also be an RLC PDU, which includes the PDCP PDU. The PDCP PDU serves as the RLC SDU, and adding an RLC header transforms it into an RLC PDU. In this case, the PDCP SN of the PDCP PDU can also be referred to as the PDCP SN corresponding to the second data packet, or the PDCP SN of the RLC PDU corresponding to the second data packet. Furthermore, in this scenario, the RLC SN of the second data packet can also be determined based on the first SN.

[0122] Using the above method, access network devices can determine the PDCP SN of the PDCP PDU corresponding to the first data packet based on the first SN in the first data packet. When different access network devices determine their respective PDCP SNs based on the first SN in the first data packet, the PDCP SNs determined by different access network devices for data packets with the same first SN from the core network device are consistent. Thus, when a UE switches between different access network devices, the transmission progress of MBS services between the two access network devices can be determined based on the transmission status of the PDCP SNs of the different access network devices, and further, the loss of MBS service data packets can be avoided through a data forwarding mechanism. For example, if two base stations determine that the source base station's transmission progress is faster based on the transmission status of the PDCP SN, the source base station where the UE was before the switch can forward a portion of the data packets to the target base station where the UE is after the switch. The target base station then sends this portion of the data packets to the UE after the switch, preventing the loss of this portion of the data packets.

[0123] The following example illustrates how access network devices determine the PDCP SN in the second data packet.

[0124] Method 1: The access network device determines the method for setting the PDCP SN based on the MBS session or the mapping relationship between QoS flows and DRBs in the MBS session.

[0125] Optionally, the access network device may decide how to map an MBS session or QoS flows within an MBS session to a data DRB for transmission. Alternatively, the access network device may receive the mapping between an MBS session or QoS flows within an MBS session and a DRB from the core network device or other access network devices.

[0126] In one possible example, when the mapping between the MBS session to which the first data packet belongs and a certain DRB is one-to-one (or in other words, there is a one-to-one correspondence between the MBS session and the DRB), the access network device can determine the PDCP SN in the second data packet based on the GTP-U SN in the first data packet. Here, a one-to-one mapping between the MBS session and the DRB means that all data packets of that MBS session are sent to the UE through that DRB, and data packets of other MBS sessions are not transmitted through that DRB.

[0127] The following is combined Figure 11 This explains how the access network device determines the PDCP SN of the PDCP PDU when the mapping relationship between the MBS session to which the first data packet belongs and a certain DRB is one-to-one.

[0128] After the core network equipment receives the data packet for MBS service from the server, when sending the same first data packet (where the same data packet means that the content and / or size of the data packet are the same) to different access network equipment (for example, access network equipment #1 and access network equipment #2 are different access network equipment), it needs to carry the same GTP-U SN number in the first data packet sent to the two access network equipment. After receiving the first data packet, access network equipment #1 and access network equipment #2 set their respective PDCP SN according to the GTP-U SN.

[0129] The PDCP SN can be equal to the GTP-U SN, or there can be a fixed difference between the PDCP SN and the GTP-U SN. The difference can be specified by the protocol or indicated by other network devices (core network devices or other access network devices).

[0130] like Figure 11 As shown, QoS flow A and QoS flow B are transmitted through the same tunnel (or GTP-U tunnel), meaning they belong to the same MBS session. Both QoS flow A and QoS flow B are mapped to the same DRB, or in other words, all data packets in this MBS session are transmitted through the same DRB, or there is a one-to-one mapping between this MBS session and this DRB. Therefore, when different access network devices determine the PDCP SN of data packets transmitted in this tunnel, they can ensure that the PDCP SN and the GTP-U SN of the data packets in the tunnel satisfy the following relationship:

[0131] PDCP SN = GTP - U SN + k1;

[0132] Where k1 = 0, ±1, ±2, ±3...

[0133] In another possible example, when there is a one-to-one mapping between the first QoS flow to which the first data packet belongs and the first DRB, the access network device can determine the PDCPSN in the second data packet based on the GTP-U SN in the first data packet. The first QoS flow can be one of the QoS flows that does not include at least one in the first session. Here, a one-to-one mapping between QoS flows and DRBs means that all data packets in the QoS flow are sent to the UE through the DRB corresponding to the QoS flow, and data packets of other QoS flows in the session besides the QoS flow are not transmitted through the DRB.

[0134] The following is combined Figure 12 This explains how the PDCP SN of the PDCP PDU is determined when the mapping relationship between the QoS flow to which the first data packet belongs and a certain DRB is one-to-one.

[0135] After the core network equipment receives the data packet for MBS service from the server, it sends the first data packet to the two access network devices through the QoS flow between access network device #1 and access network device #2, respectively. The first data packet sent to the two access network devices carries the same QFI SN. In access network device #1, the QoS flow to which the first data packet belongs corresponds one-to-one with a DRB of access network device #1, and in access network device #2, the QoS flow to which the first data packet belongs corresponds one-to-one with a DRB of access network device #2.

[0136] After receiving the first data packet, access network device #1 and access network device #2 set the PDCP SN of the corresponding data packet according to the QFI SN.

[0137] The PDCP SN can be equal to the QFI SN, or there can be a fixed difference between the PDCP SN and the QFI SN. The difference can be specified by the protocol or indicated by other network devices (core network devices or other access network devices).

[0138] like Figure 12 As shown, taking access network device #1 as an example, QoS flow A and QoS flow B are transmitted through a unified tunnel, and QoS flow A is mapped to DRB A (i.e., corresponding to PDCP entity A) for transmission, while QoS flow B is mapped to DRB B (i.e., corresponding to PDCP entity B) for transmission. Therefore, when different access network devices determine the PDCP SN of the data packets transmitted in QoS flow A or QoS flow B, they can ensure that the PDCP SN and the QFI SN of the data packets satisfy the following relationship:

[0139] PDCP SN = QFI SN + k2;

[0140] Where k2 = 0, ±1, ±2, ±3...

[0141] It should be understood that in Method 1 above, the mapping of access network device sessions (or QoS flows) to DRBs can be either all QoS flows within a session corresponding to a single DRB (or a one-to-one correspondence between sessions and DRBs), or each QoS flow within a session corresponding to a single DRB. This depends on the implementation of the access network device; each access network device can decide which mapping method to use. Optionally, multiple access network devices can ensure consistency in the mapping method of MBS sessions or QoS flows to DRBs across different access network devices through interactive signaling or operation administration and maintenance (OAM) management. Taking different access network devices, including access network device #1 and access network device #2, as an example, the mapping method from MBS sessions or QoS flows to DRBs is consistent across different access network devices. For example, if the MBS session between the core network device to which the MBS service data packet belongs and access network device #1 corresponds one-to-one with a DRB, then the MBS session between the core network device to which the same data packet belongs and access network device #2 corresponds one-to-one with a DRB; or, if the QoS flow between the core network device to which the MBS service data packet belongs and access network device #1 corresponds one-to-one with a DRB, then the QoS flow between the core network device to which the same data packet belongs and access network device #2 corresponds one-to-one with a DRB.

[0142] for example Figure 4 In this configuration, both access network device #1 and access network device #2 establish a one-to-one mapping relationship between sessions composed of QoS flows A, B, and C and DRB A. Upon receiving a data packet from QoS flows A, B, and / or C, access network device #1 and access network device #2 determine the corresponding PDCP SN based on the GTP-USN of the data packet. Alternatively, if both access network device #1 and access network device #2 establish a one-to-one mapping relationship between QoS flows A and DRB A, upon receiving a data packet from QoS flows A, access network device #1 and access network device #2 determine the corresponding PDCP SN based on the QFI SN of the data packet.

[0143] If the SgNB and TgNB use different mapping methods for the same session, the session-to-DRB mapping is first established on the TgNB using the same mapping method as the SgNB, and then the UE is handed over from the SgNB to the TgNB. After the handover process is completed, the UE receives data packets forwarded from the SgNB to the TgNB through the newly established DRB, and also receives data packets sent from the core network to the TgNB through the existing DRB on the TgNB.

[0144] Based on Method 1, how the access network device configures the PDCP SN depends on how the access network device determines the mapping relationship between sessions (or QoS flows) and DRBs. If the access network device determines that the mapping relationship is one-to-one between MBS sessions and DRBs, then the PDCP SN is configured in the manner described in Method 1 when MBS sessions and DRBs are one-to-one. If the access network device determines that the mapping relationship is one-to-one between some QoS flows in the MBS session and DRBs, then the PDCP SN is configured in the manner described in Method 1 when QoS flows and DRBs are one-to-one.

[0145] Method 2: The access network device can report the mapping relationship between the session (or QoS flow) and the DRB to the core network device. When the core network device sends a data packet to the access network device, it determines the first SN of the data packet based on at least one of the three factors: the QoS flow to which the data packet belongs, the session to which the data packet belongs, and the mapping relationship between the session (or QoS flow) and the DRB reported by the access network device. The access network device then determines the PDCP SN corresponding to the data packet based on the first SN.

[0146] In this approach, the mapping relationship between sessions (or QoS flows) and DRBs determined by the access network device is not restricted. The access network device only needs to report this mapping relationship to the core network device after determining it. Once the core network knows the mapping relationship between the access network device's sessions (or QoS flows) and DRBs, it uniformly sets the corresponding first SN for data packets of multiple QoS flows mapped to the same DRB, according to the sending order and the principles of contiguous and ascending order.

[0147] For example, the access network device may send first information to the core network device, which indicates the mapping relationship between at least one QoS flow and at least one DRB in the first session, wherein the at least one DRB includes the first DRB to which the first data packet belongs. After receiving the first information, the core network device sets the first SN of each data packet in the first session in ascending order according to the GTP-U SN in the data packet (or according to the order in which the core network device transmits the data packets), and then sends the data packet to the access network device. Taking the first DRB as an example, the first SNs of the data packets in all QoS flows corresponding to the first DRB are set consecutively. For example, in these data packets, the first SNs of the data packets are 1, 2, 3, ... in ascending order of GTP-U.

[0148] Optionally, the access network device can send the identifier or index of the QoS flows mapped to the same DRB as the first information to the core network. That is, the first information indicates which QoS flows are mapped to the same DRB or which QoS flow packets need to have their first SN uniformly set. Alternatively, the access network device can send the identifier or index of the QoS flows mapped to the same DRB, along with the identifier or index of that DRB, as the first information to the core network device. Optionally, this first information can be sent to the core network during the establishment of an MBS session, QoS flow, or MBS flow.

[0149] For example Figure 13 As shown, QoS flow A and QoS flow C are mapped to the same DRB. The core network device can start from an initial value (e.g., 1) and set the first SN in the data packets of QoS flow A and QoS flow C in ascending order according to the transmission sequence (or the GTP-U SN sequence). However, for QoS flow B, since it is mapped to a separate DRB (i.e., mapped to PDCP entity B), the core network device can start from an initial value (e.g., 1) and set the first SN in the data packets of QoS flow B in ascending order according to the transmission sequence (or the GTP-U SN sequence). It should be understood that because QoS flow A and QoS flow C are mapped to the same DRB, the first SN of the data packets in QoS flow A and QoS flow C in the above example needs to be set uniformly; while because QoS flow B is mapped to a separate DRB, the setting of the first SN of the data packets in QoS flow B is not affected by other QoS flow data packets, or in other words, the first SN of the data packets in QoS flow B is set independently.

[0150] Optionally, the first SN mentioned above can be a QFI SN or a newly defined SN.

[0151] For example, this newly defined SN can be called an MBS SN. Taking the MBS SN as an example, a new bit field can be extended into the header format of existing core network data packets (such as the GTP-U header format) to carry the MBS SN. That is, the MBSSN can be carried in another bit field extended in addition to the existing QFI SN field and GTP-U SN field.

[0152] Based on the mapping relationship between sessions (or QoS flows) and DRBs, the core network equipment sets the first SN of data packets, and the access network equipment sets the corresponding PDCP SN of the data packets according to the first SN. For example, the PDCP SN corresponding to the data packet and the first SN can satisfy the following relationship:

[0153] PDCP SN = First SN + k3;

[0154] Where k3 = 0, ±1, ±2, ±3...

[0155] Optionally, if the core network device does not receive the first information from the access network device, it assumes the mapping relationship between the session (or QoS flow) and the DRB is the default mapping method. This default mapping method can be determined in advance through information exchange or specified in the protocol. Further, if the default mapping method is a one-to-one correspondence between sessions and DRBs, the default first SN is numbered using a unified first SN number for all QoS flow data packets within a session. The access network device determines the corresponding PDCP SN based on the first SN of each data packet. Conversely, if the default mapping method is a one-to-one correspondence between each QoS flow in a session and the DRB, the default first SN is numbered using an independent first SN number for each QoS flow data packet within a session. The access network device determines the corresponding PDCP SN based on the first SN of each data packet.

[0156] Method 3: The access network device sets the PDCP SN corresponding to the received data packets in ascending order according to the size order (not necessarily consecutive) of the GTP-U SN of the received data packets.

[0157] For example, when the first data packet belongs to the first session and the first DRB corresponds to some or all of the QoS flows in at least one QoS flow contained in the first session, the first SN may include the GTP-U SN of the first data packet (hereinafter referred to as the first GTP-U SN), and the first PDCP of the first data packet is represented as N0. Then the access network device may determine the PDCP SN corresponding to at least one third data packet in the first session whose GTP-U SN is greater than the first GTP-U SN according to the following method: determine the PDCP SN corresponding to the i-th third data packet in at least one third data packet after sorting in a first order as N0+i, wherein the first order includes at least one third data packet arranged in ascending order of the included GTP-U SN, and i is an integer greater than or equal to 0.

[0158] This method does not restrict the mapping relationship between sessions (or QoS flows) and DRBs. Sessions can be mapped one-to-one with DRBs, or QoS flows in a session can be mapped one-to-one with DRBs, or other mapping methods can be used.

[0159] For example, QoS flows A, B, and C belong to the same MBS session. QoS flows A and C are mapped to the same DRB (i.e., mapped to PDCP entity A), while QoS flow B is mapped to another DRB (i.e., mapped to PDCP entity B). Therefore, the GTP-USNs of the data packets transmitted to PDCP entity A are not consecutive. For instance, starting from a certain time T0, the GTP-USNs of at least one data packet received by PDCP entity A are 1, 3, 4, and 6 respectively. In other words, the GTP-USNs of at least one third data packet are 1, 3, 4, and 6 respectively. In this case, the GTP-USNs can be arranged in ascending order, and the corresponding PDCPSNs can be set consecutively starting from N0+1. That is, the PDCP SNs corresponding to the data packets with GTP-USNs of 1, 3, 4, and 6 are N0+1+k4, N0+2+k4, N0+3+k4, and N0+4+k4 respectively, where k4 = 0, ±1, ±2, ±3, ... Wherein, N0 can be the GTP-U SN value of the last data packet received by PDCP entity A before T0, such as the first data packet shown in this application.

[0160] It should be understood that if PDCP entity A has not received any other data packets before time T0, then the value of N0 is 0. N0 can also be determined based on indications from the core network or other access network devices.

[0161] When different access network devices all apply this method 3, the PDCP SN set by different access network devices for the same MBS service data packets is the same, which can ensure the continuity of data reception when the UE switches between different access network devices.

[0162] Based on Method 3, assuming that one of the SgNB and TgNB starts the MBS service first and the other starts the service later, the PDCP SN of the data packets may still be inconsistent because the PDCP SN of the first data packet sent by the two access network devices is inconsistent.

[0163] For example, the core network sends the first data packet of the first MBS service to the SgNB through the first session. The SgNB determines the PDCP SN (i.e., the first PDCP SN) of the first data packet to be N0, and the GTP-U SN of the first data packet to be the first GTP-U SN. The TgNB starts sending the data packets of the first MBS service after the SgNB sends the first data packet. For example, the first data packet sent by the TgNB is the next data packet after the first data packet sent by the core network (the GTP-U of this data packet is the first GTP-U SN+1). Taking k4=0 as an example, according to the rules of Method 3, the PDCP SN of the first data packet sent by the TgNB is 1 (i.e., for the TgNB, N0=0), but the PDCP SN corresponding to the next data packet sent by the SgNB is N0+1 (for the SgNB, N0≠0, for example, if the first data packet is the first data packet received by the SgNB, then N0=1). Therefore, the PDCP SNs of the same data packet sent by the SgNB and the TgNB are inconsistent.

[0164] Taking the example of the SgNB sending MBS service first, followed by the TgNB sending the same MBS service, one possible solution is for the SgNB or core network to send second information to the TgNB. This second information indicates the correspondence between at least one PDCP SN and at least one GTP-U SN (which can be referred to as the first correspondence). This first correspondence may include the correspondence between the GTP-U SN of the first data packet of the MBS service sent by the TgNB through the first DRB and the corresponding PDCP SN. The PDCP SN can be determined by the SgNB based on the GTP-U SN of the data packet using method three. Another possible solution is for the SgNB or core network to send the PDCP SN corresponding to the first data packet after the MBS session or MBS flow is established to the TgNB.

[0165] The TgNB can receive the first correspondence or the PDCP SN corresponding to the first data packet, and determine the PDCP SN of the first data packet to be sent based on the first correspondence or the PDCP SN corresponding to the first data packet. Thereafter, it determines the PDCP SN of subsequent data packets according to method three. Therefore, after the TgNB starts sending the MBS service, the PDCP SN of the same data packets sent by the SgNB and TgNB remains consistent.

[0166] Optionally, the first correspondence may include: the correspondence between the first PDCP SN (i.e., N0) of the first data packet and the first GTP-U SN in the aforementioned example; or, the correspondence between N0+i and the GTP-U SN of the i-th third data packet in at least one third data packet ordered in the first order, wherein N0+i is the PDCP SN of the i-th third data packet received by the SgNB after the first data packet; or, the correspondence between N0+I+1 and M+1, wherein I is the number of the at least one third data packet, and M is the GTP-U SN of the i-th third data packet in at least one third data packet ordered in the first order. It should be understood that M+1 may be the GTP-USN of a data packet not received by the SgNB.

[0167] Optionally, the PDCP SN corresponding to the first data packet may be, for example, N0, N0+i, or N0+i+1. Then, the TgNB can determine the PDCP SN of data packets sent to the terminal device through the same DRB, starting from the PDCP SN corresponding to the first data packet.

[0168] Based on Method 3, if a data packet sent from the core network device to the access network device is lost, it will also cause the PDCP SN of the same data packet determined by different access network devices according to Method 3 to be inconsistent.

[0169] If packet loss occurs during the transmission of MBS data packets from the core network to the access network equipment, it will affect the PDCP SN determination rules shown in Method 3. When packet loss occurs in either the SgNB or TgNB, the PDCP SNs of the same MBS data packets transmitted to the SgNB and TgNB will be different. For example, if the GTP-U SNs of PDCP A data packets transmitted to the SgNB are 1, 3, 4, and 6, then the PDCP SN corresponding to the data packet with GTP-U SN 6 is 4. However, the GTP-U SNs of PDCPA data packets transmitted to the TgNB are 1, 3, and 6, meaning the data packet with GTP-U SN 4 is lost. In this case, according to Method 3, the GTP-USN will configure the PDCP SN of the data packet with GTP-U SN 6 to be 3, causing packet loss after the UE switches from the SgNB to the TgNB due to inconsistent interpretation.

[0170] To address this issue, the access network device can determine the PDCP SN of the packet with the smallest GTP-U SN after a series of consecutively lost packets based on the number of consecutively lost packets across all QoS flows corresponding to the DRB, thus maintaining the continuity of PDCP SNs for data packets. The number of consecutively lost packets refers to the number of adjacent lost packets among all packets in at least one QoS flow corresponding to the same DRB. For example, if the GTP-U values ​​of all QoS flows corresponding to the same DRB are 1, 2, 4, and 6, but the access network device receives packets with GTP-U values ​​of 1 and 6 for the same DRB, then packets with GTP-U values ​​of 2 and 4 are considered consecutively lost, and the number of consecutively lost packets is 2. Conversely, if the access network device receives packets with GTP-U values ​​of 1, 2, and 6 for the same DRB, then packets with GTP-U value of 4 are considered consecutively lost, and the number of consecutively lost packets is 1.

[0171] Specifically:

[0172] The access network device can identify whether packet loss has occurred based on the QFI SN of the received data packet and the QFI SN of the previously received data packets in the QoS flow to which the data packet belongs. Because in Method 3, the core network device sets the QFI SN of the data packets for each QoS flow continuously, if the QFI SN of the data packets received by the access network device in the same QoS flow are not continuous, it can be determined that packet loss has occurred, and the number N of continuously lost data packets can be determined.

[0173] Furthermore, the access network device can determine the GTP-USN of the lost data packet based on the QFI SN of the lost data packet, and obtain the correspondence between the GTP-USN and PDCP SN among all data packets of all QoS flows with the same DRB as the QoS flow to which the lost data packet belongs. In addition, based on the GTP-U SN of the lost data packet, the device can determine the PDCP SN corresponding to the data packet whose GTP-U SN is greater than that of the lost data packet.

[0174] For example, in the previous example, if the GTP-U SN of the data packets transmitted to PDCP entity A to TgNB is 1, 3, or 6, then TgNB can determine that there is packet loss based on the QFI SN of the received data packets, and the number of consecutive packet losses is represented by L. In this example, L = 1.

[0175] When determining the PDCP SN corresponding to a data packet with GTP-U SN of 6, TgNB needs to consider the number of consecutive packet losses, L. For example, in the QoS flow data packets received by PDCP entity A, if the PDCP SN corresponding to the data packet before the lost data packet is N1 as determined by the access network device according to method three, then the access network device can determine that the PDCP SN corresponding to the first data packet received by PDCP entity A after packet loss is N1+L+1.

[0176] Furthermore, based on the scheme shown in Method 3, if the GTP-U of the data packets received by the access network device is out of order, it will also lead to inconsistencies in the PDCP SN determined by different access network devices for the same data packets sent by the core network device. To solve this problem, the access network device is required to sort the data packets according to the size of their GTP-U when determining the PDCP SN, and then determine the PDCP SN of the data packets according to the GTP-U of the sorted data packets.

[0177] The values ​​of K1, K2, K3, and / or K4 can be indicated by the core network equipment, or they can be predefined values. Specifically, the value of K1 is the same for different access network devices; similarly, the value of K2 is the same for different access network devices; similarly, the value of K3 is the same for different access network devices; and similarly, the value of K4 is the same for different access network devices.

[0178] This application also provides another communication method, which will be described in detail below.

[0179] In many wireless communication scenarios, terminal devices need to initiate random access procedures to network devices, such as entering the connected state from an idle or inactive state, RRC re-establishment process, uplink synchronization failure, etc. (For more scenarios that require initiating random access, please refer to the scenarios in section 9.2.6 of 3GPP protocol 38.300).

[0180] Random access procedures are divided into two types: four-step random access and two-step random access. Each of these two types of random access includes two random access methods: contention-based random access and contention-free random access.

[0181] The contention-based four-step random access mechanism (CRM) consists of the following steps: First, in Message 1, the terminal device sends a preamble to the network device via physical random access resources. After sending the preamble, the terminal device opens a random access response receiving window to receive the random access response sent by the network device. Second, after receiving the preamble from the terminal device, the network device sends Message 2 to the terminal device. Message 2 contains the random access response, which includes at least one of the following: preamble number, timing adjustment amount, uplink grant, and temporary C-RNTI. Third, according to the instructions in Message 2, the terminal device sends Message 3 on the corresponding uplink resources. Message 3 may contain at least one of the following: RRC reconstruction request, RRC establishment request, or RRC recovery request, etc. After sending Message 3, the terminal device starts a timer to detect the conflict resolution message using the C-RNTI allocated in the random access response. Fourth, after receiving Message 3 from the terminal device, the network device sends Message 4, the conflict resolution message, to the terminal device. If the terminal device receives the conflict resolution message during the timer's execution, it considers the random access successful; otherwise, it returns to Step 1 and resends Message 1.

[0182] The non-contention-based four-step random access method consists of the following steps: First, in message one, the terminal device sends a dedicated preamble allocated by the base station to the network device through physical random access resources. After sending the dedicated preamble, the terminal device opens a random access response receiving window to receive the random access response sent by the network device. Second, after receiving the preamble from the terminal device, the network device sends message two to the terminal device. Message two contains the random access response, which includes at least one of the following: preamble number, timing adjustment amount, uplink grant, and temporary C-RNTI. Upon receiving the random access response, the terminal device considers the random access successful.

[0183] Contention-based two-step random access consists of the following steps: First, in message A, the terminal device sends a preamble to the network device via physical random access resources and load information via the physical uplink shared channel. After sending message A, the terminal device opens a random access response receiving window to receive the random access response sent by the network device. Second, after receiving message A from the terminal device, the network device sends message B to the terminal device. Message B contains the random access response, which includes at least one of the following: preamble number, timing adjustment amount, uplink grant, and temporary C-RNTI. Upon receiving message B, the terminal device considers the random access successful. If a fallback instruction is received in message B, the terminal device returns to the four-step random access process, sends message three to the network device via the uplink resources in the fallback instruction, and listens for conflict resolution messages. If conflict resolution fails, the terminal device returns to step one and resends message A.

[0184] The non-contention-based two-step random access process consists of the following steps: First, in message A, the terminal device sends a dedicated preamble to the network device via physical random access resources and load information via dedicated physical uplink shared channel resources. After sending message A, the terminal device opens a random access response receiving window to receive the random access response sent by the network device. Second, after receiving message A from the terminal device, the network device sends message B to the terminal device. Message B contains the random access response, which includes at least one of the following: preamble number, timing adjustment amount, uplink grant, and temporary C-RNTI. Upon receiving message B, the terminal device considers the random access successful. If a fallback instruction is received in message B, the terminal device falls back to the four-step random access process, sending message three to the network device via the uplink resources in the fallback instruction and listening for conflict resolution messages. If conflict resolution fails, the terminal device returns to step one and resends message A.

[0185] The above describes four-step random access and two-step random access. When a UE needs to initiate random access, how to choose between two-step random access and four-step random access is the problem that needs to be solved here. Especially in non-terrestrial communication or satellite communication scenarios, if the selection method is not specified, a large number of terminal devices may use the same random access method, resulting in a shortage of such random access resources.

[0186] The communication method provided in this application embodiment may include the following steps:

[0187] Step 1: The access network device sends first information to the terminal device. This first information includes a first threshold or a first indication. This first threshold or indication is used by the terminal device to determine whether to use a four-step or two-step random access procedure when initiating random access. Alternatively, the first threshold may not need to be sent by the access network device to the terminal device; instead, it can be a fixed threshold defined by a protocol. This first threshold can be a distance threshold, a time threshold, or a power threshold. The first information can be sent via broadcast system information or via RRC signaling. Furthermore, the first threshold can also be a fixed value.

[0188] Step 2: The terminal device receives the first information, which includes a first threshold or a first indication. The first threshold is used by the terminal device to determine whether to use a four-step random access procedure or a two-step random access procedure when initiating random access.

[0189] Step 3: When initiating random access, the terminal device determines whether to use a four-step random access procedure or a two-step random access procedure based on the first information.

[0190] Specifically, it includes:

[0191] If the first information includes a first threshold, and the first threshold is a distance threshold, then when the distance between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can choose two-step random access. This relationship can be a distance greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a relay device, or an access network device. If the first threshold is a time threshold, then when the one-way or two-way propagation delay between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can choose two-step random access. This relationship can be a one-way or two-way propagation delay greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a relay device, or an access network device. If the first threshold is a power threshold, then when the maximum transmit power or maximum usable power of the terminal device exceeds the first threshold, two-step random access can be used.

[0192] If the first information includes a first indication, the first indication is used to indicate which terminal devices use a two-step random access procedure and which terminal devices use a four-step random access procedure. The terminal device determines whether to use a four-step or two-step random access procedure based on the first indication and / or a first criterion. The first criterion can be a criterion based on terminal device ID, a criterion based on terminal device type, or a random criterion. In the criterion based on terminal device ID, terminal devices may be divided into two groups based on the parity of their IDs, with one group using two-step random access and the other using four-step random access. Which group (odd or even) uses two-step random access can be dynamically changed through the first indication information. For example, the first indication information can indicate that terminal devices with odd IDs use two-step random access or four-step random access.

[0193] In criteria based on terminal device type, higher-specification terminal devices may be given priority for two-step random access. The specific terminal device specifications eligible for two-step random access can be communicated to the terminal device via a first instruction or specified through a protocol. In random access criteria, the access network device may send a first value to the terminal device in the first instruction or first threshold. The terminal device then generates a random number, compares it with the first value, and determines whether to use two-step or four-step random access based on their relative values. For example, if the random number is less than the first value, a two-step random access procedure may be used; if it is greater than the first value, two-step random access may also be used.

[0194] Furthermore, 5G communication introduces SUL (Supplementary Uplink Carrier), a new spectrum pairing method that allows downlink data to be transmitted on the C-band, while uplink data can be transmitted on either the C-band or Sub-3G (SUL, e.g., 1.8GHz), thereby improving uplink coverage. Now, assuming a terminal device initiates random access within a cell, how does it decide whether to initiate random access on a non-SUL or SUL network? Especially in non-terrestrial or satellite communication scenarios, failing to specify how to make this choice can reduce the success rate of random access for the terminal device.

[0195] The communication method provided in this application embodiment may include the following steps:

[0196] Step 1: The access network device sends first information to the terminal device. This first information includes a first threshold or a first indication. This first threshold or indication is used by the terminal device to determine whether to initiate random access on a non-SUL carrier or an SUL carrier when initiating random access. Alternatively, the first threshold may not need to be sent by the access network device to the terminal device; instead, it can be a fixed threshold defined by a protocol. The first threshold can be a distance threshold, a time threshold, or a power threshold; alternatively, the first threshold can be a fixed value.

[0197] Step 2: The terminal device receives the first information, which includes a first threshold or a first indication. The first threshold is used by the terminal device to determine whether to initiate random access on a non-SUL carrier or on a SUL carrier when initiating random access.

[0198] Step 3: When initiating random access, the terminal device determines, based on the first information, whether to initiate random access on a non-SUL carrier or on a SUL carrier.

[0199] Specifically, it includes:

[0200] If the first information includes a first threshold, and the first threshold is a distance threshold, then when the distance between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can choose to initiate random access on a non-SUL carrier. This relationship can be a distance greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a terminating device, or an access network device. If the first threshold is a time threshold, then when the one-way or two-way propagation delay between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can choose to initiate random access on a non-SUL carrier. This relationship can be a one-way or two-way propagation delay greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a terminating device, or an access network device. If the first threshold is a power threshold, then when the maximum transmit power or maximum usable power of the terminal device exceeds or falls below the first threshold, random access can be initiated on a non-SUL carrier.

[0201] If the first information includes a first indication, the first indication is used to indicate which terminal devices initiate random access on non-SUL carriers and which terminal devices initiate random access on SUL carriers. The terminal devices determine whether to initiate random access on non-SUL carriers or SUL carriers based on the first indication and / or a first criterion. The first criterion can be a criterion based on terminal device ID, a criterion based on terminal device type, a criterion based on terminal device performance, or a random criterion. In the criterion based on terminal device ID, terminal devices may be divided into two groups based on the parity of their IDs, with one group initiating random access on non-SUL carriers and the other on SUL carriers. Which of the two groups (odd and even) initiates random access on non-SUL carriers can be dynamically changed through the first indication information. For example, the first indication information can indicate that terminal devices with odd IDs initiate random access on non-SUL carriers, or it can indicate that terminal devices with odd IDs initiate random access on SUL carriers.

[0202] In the criteria based on terminal equipment type, higher-specification terminal equipment may preferentially initiate random access on either non-SUL carriers or SUL carriers. The specific specifications of which terminal equipment can initiate random access on non-SUL carriers can be communicated to the terminal equipment through a first indication or specified in the protocol. In the random access criteria, the access network equipment may send a first value to the terminal equipment in the first indication or first threshold. The terminal equipment randomly generates a random number, compares it with the first value, and decides whether to initiate random access on a non-SUL carrier or an SUL carrier based on the relationship between the two values. For example, if the random number is less than the first value, random access may be initiated on a non-SUL carrier, or if it is greater than the first value, random access may be initiated on a non-SUL carrier.

[0203] As mentioned above, when a terminal device decides to initiate contention-based random access, it selects a preamble to send in message 1. Currently, each cell has 64 available preambles, and the UE selects one to transmit in message 1. These preambles are divided into two parts: one for contention-based random access and the other for non-contention-based random access. The preambles used for contention-based random access can be further divided into two groups: group A and group B. When initiating contention-based random access, how the terminal device decides which group of preamble to choose, especially in non-terrestrial or satellite communication scenarios, is crucial. If the selection method is not specified, a large number of terminal devices may use the same group of preambles, leading to an excessively high probability of collisions.

[0204] The communication method provided in this application embodiment may include the following steps:

[0205] Step 1: The access network device sends first information to the terminal device. This first information includes a first threshold or a first indication. This first threshold or indication is used by the terminal device to determine whether to initiate random access on a non-SUL carrier or an SUL carrier when initiating random access. Alternatively, the first threshold may not need to be sent by the access network device to the terminal device; instead, it can be a fixed threshold defined by a protocol. This first threshold can be a distance threshold, a time threshold, a power threshold, or a message size threshold; alternatively, the first threshold can be a fixed numerical value.

[0206] Step 2: The terminal device receives the first information, which includes a first threshold or a first indication. The first threshold is used by the terminal device to determine which group of preambles to use when initiating random access.

[0207] Step 3: When initiating random access, the terminal device determines which preamble to use based on the first information.

[0208] Specifically, it includes:

[0209] If the first information contains a first threshold, and the first threshold is a distance threshold, then when the distance between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can select the preamble in group A. This relationship can be that the distance is greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a relay device, or an access network device. If the first threshold is a time threshold, then when the one-way or two-way propagation delay between the terminal device and the first network device satisfies a certain relationship with the first threshold, the terminal device can select the preamble in group A. This relationship can be that the one-way or two-way propagation delay is greater than, equal to, or less than the first threshold. The first network device can be a satellite device, a relay device, a relay device, or an access network device. If the first threshold is a power threshold, then when the maximum transmit power or maximum usable power of the terminal device exceeds or falls below the first threshold, group A can be selected. The preamble in group A; if the first threshold is the information size threshold, then when the size of message 3 to be sent by the terminal device is larger than the first threshold, the preamble in group B can be selected.

[0210] If the first information includes a first indication, the first indication is used to indicate which terminal devices can choose the preamble in group A and which terminal devices can choose the preamble in group B. The terminal devices determine whether to choose the preamble in group A or group B based on the first indication and / or a first criterion. The first criterion can be a criterion based on terminal device ID, a criterion based on terminal device type, a criterion based on terminal device performance, or a random criterion. In the criterion based on terminal device ID, the terminal devices may be divided into two groups based on the parity of their IDs, with one group choosing the preamble in group A and the other choosing the preamble in group B. Which group (odd or even) chooses the preamble in group A can be dynamically changed through the first indication information. For example, the first indication information can indicate that terminal devices with odd IDs choose the preamble in group A or group B.

[0211] In the criteria based on terminal device type, higher-specification terminal devices may preferentially choose either the preamble from group B or group A. This is because higher-specification terminal devices may send larger messages or require lower access latency. The specific terminal device specifications that can choose the preamble from group A can be communicated to the terminal device via a first indication or specified in the protocol. In random criteria, the access network device may send a first value to the terminal device in the first indication or first threshold. The terminal device then randomly generates a random number, compares it with the first value, and decides whether to choose the preamble from group A or group B based on their relative magnitudes. For example, if the random number is less than the first value, the preamble from group A is chosen; if it is greater than the first value, the preamble from group A is chosen.

[0212] Based on the same inventive concept, embodiments of this application also provide a communication device for implementing the functions described above by the terminal device, access network device, and / or core network device. This device may include... Figures 6 to 9 The structure shown.

[0213] This application provides a communication system. The communication system may include the access network equipment and core network equipment described in the above embodiments. Optionally, the communication system may include... Figure 1 or Figure 4 The structure shown is illustrated. This communication device can be used to implement... Figure 10 The steps in the communication method shown are implemented by the access network equipment and / or the core network equipment.

[0214] This application also provides a computer-readable storage medium for storing a computer program. When the computer program is executed by a computer, the computer can implement the methods provided in the above embodiments. Figure 10 The embodiments shown depict processes related to access network equipment and / or core network equipment.

[0215] This application also provides a computer program product for storing a computer program. When the computer program is executed by a computer, the computer can implement the methods provided in the above embodiments. Figure 10 The embodiments shown depict processes related to access network equipment and / or core network equipment.

[0216] This application also provides a chip or chip system (or circuit) that may include a processor. The processor can be used to call programs or instructions in memory to execute the methods provided in the above embodiments. Figure 10 The illustrated embodiments describe processes related to access network equipment and / or core network equipment. The chip system may include the chip itself, as well as other components such as memory or transceivers.

[0217] It should be understood that the processor mentioned in the embodiments of this application can be a CPU, or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0218] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0219] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) is integrated into the processor.

[0220] It should be noted that the memories described herein are intended to include, but are not limited to, these and any other suitable types of memories.

[0221] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes 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.

[0222] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0223] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0224] In the several embodiments provided in this application, it should be understood that the disclosed communication methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0225] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0226] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0227] If the above functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the contributing part, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned computer-readable storage medium can be any available medium that a computer can access. For example, but not limited to: computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), universal serial bus flash disk, portable hard disk, or other optical disc storage, 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.

[0228] The above are merely specific embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be included within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A communication method characterized by comprising: Applied to a first access network device, comprising: receiving a first data packet of a first session from a core network device, the first data packet comprising a first sequence number SN; sending a second data packet to a terminal device, the second data packet belonging to data of a first data radio bearer DRB, the second data packet comprising a packet data convergence protocol PDCP protocol data unit PDU, the PDCP PDU being obtained according to the first data packet, and a PDCP SN of the PDCP PDU being determined according to the first SN; The method further comprises: sending first information to the core network device, the first information indicating a mapping relationship between at least one QoS flow included in the first session and at least one DRB, the mapping relationship being used by the core network device to set the first SN, and the at least one DRB including the first DRB.

2. The method of claim 1, wherein, The first information indicates a mapping relationship between each DRB in the at least one DRB and one or more QoS flows in the at least one QoS flow.

3. The method of claim 1, wherein, The first DRB corresponds to part or all of the QoS flows in the at least one QoS flow included in the first session; The first SN comprises a first GTP-U SN, and a first PDCP SN is N0, and the method further comprises: receiving at least one third data packet from the core network device, the at least one third data packet being mapped to the first DRB, and the at least one third data packet containing a GTP-U SN greater than the first GTP-U SN, determining that the corresponding PDCP SN of the ith third data packet in the at least one third data packet sorted in a first order is N0+i, wherein the first order comprises an order from small to large of the GTP-U SNs contained in the at least one third data packet respectively, and i is an integer greater than or equal to 0.

4. The method of claim 3, wherein, Further comprising: sending second information to a second access network device, the second information indicating a correspondence between at least one PDCP SN and at least one GTP-U SN, the correspondence comprising at least one of: N0 corresponds to the first GTP-U SN; or N0+i corresponds to the GTP-U SN of the ith third data packet in the at least one third data packet sorted in the first order; or N0+I+1 corresponds to M+1, I being the number of the at least one third data packet, and M being the GTP-U SN of the Ith third data packet in the at least one third data packet sorted in the first order.

5. The method of claim 3 or 4, wherein, The first SN further comprises a QFI SN, and further comprising: determining the PDCP SN of the data packet with the smallest GTP-U SN after the continuously lost data packets according to the number of the continuously lost data packets in all QoS flows corresponding to the first DRB.

6. The method of claim 1, wherein, Further comprising: receiving a PDCP SN corresponding to the first SN, the PDCP SN of the PDCP PDU comprising the PDCP SN corresponding to the first SN.

7. A communication method characterized by comprising: Applied to a core network device, comprising: receive first information from the first access network device, the first information indicating a mapping relationship between at least one QoS flow included in the first session and at least one DRB; set the first SN of the data packet in the at least one QoS flow corresponding to the first DRB in ascending order according to the GTP-U SN in ascending order; send the first data packet in the first QoS flow in the first session to the first access network device, the first QoS flow being one of the at least one QoS flow included in the first session and corresponding to the first DRB.

8. The method of claim 7, wherein, The first information indicates a mapping relationship between each DRB in the at least one DRB and one or more QoS flows in the at least one QoS flow.

9. A communications device, characterized by Comprise: a transceiver module, configured to receive a first data packet of a first session from a core network device, the first data packet comprising a first sequence number SN; The transceiver module is further configured to send a second data packet to a terminal device, the second data packet belonging to data of a first data radio bearer DRB, the second data packet comprising a packet data convergence protocol PDCP protocol data unit PDU, the PDCP PDU being obtained according to the first data packet, and a PDCP SN of the PDCP PDU being determined according to the first SN; The transceiver module is further configured to send first information to the core network device, the first information indicating a mapping relationship between at least one QoS flow included in the first session and at least one DRB, the mapping relationship being used by the core network device to set the first SN, and the at least one DRB including the first DRB.

10. The communication apparatus of claim 9, wherein, The first information indicates a mapping relationship between each DRB in the at least one DRB and one or more QoS flows in the at least one QoS flow.

11. The communication apparatus of claim 9, wherein, The first DRB corresponds to part or all of the at least one QoS flow included in the first session; The first SN comprises a first GTP-U SN, and a first PDCP SN is N0, and the transceiver module is further configured to: receive at least one third data packet from the core network device, the at least one third data packet being mapped to the first DRB, and a GTP-U SN included in the at least one third data packet being greater than the first GTP-U SN; The communication device further comprises a processing module, configured to: determine that a corresponding PDCP SN of an i-th one of the at least one third data packet in a first order is N0+i, wherein the first order comprises an order of GTP-U SNs included in the at least one third data packet in ascending order, and i is an integer greater than or equal to 0.

12. The communication apparatus of claim 11, wherein, The transceiver module is further configured to: send second information to a second access network device, the second information indicating a correspondence between at least one PDCP SN and at least one GTP-U SN, the correspondence comprising at least one of: N0 corresponds to the first GTP-U SN; or N0+i corresponds to the GTP-U SN of the i-th data packet in the at least one third data packet sorted in the first order; or N0+I+1 corresponds to M+1, I is the number of third data packets, and M is the GTP-U SN of the I-th data packet in the at least one third data packet sorted in the first order.

13. The communication apparatus according to claim 11 or 12, wherein, The first SN further includes a QFI SN, and the communication apparatus further includes a processing module, configured to: determine the PDCP SN of the data packet with the smallest GTP-U SN after the consecutive lost data packets according to the number of the consecutive lost data packets in all QoS flows corresponding to the first DRB.

14. The communication apparatus of claim 9, wherein, The transceiver module is further configured to: receive the PDCP SN corresponding to the first SN, and the PDCP SN of the PDCP PDU includes the PDCP SN corresponding to the first SN.

15. A communications device, characterized by Comprising: a transceiver module, configured to receive first information from a first access network device, the first information indicating a mapping relationship between at least one QoS flow and at least one DRB included in a first session; a processing module, configured to sequentially set, in ascending order, first SNs of data packets in at least one QoS flow corresponding to a first DRB according to a GTP-U SN in ascending order from small to large, the at least one DRB including the first DRB, and the data packets in the QoS flow corresponding to the first DRB including first data packets of the first session; the transceiver module is further configured to send the first data packets to the first access network device through a first QoS flow in the first session, the first QoS flow being one of the at least one QoS flow included in the first session and corresponding to the first DRB.

16. The communication apparatus of claim 15, wherein, The first information indicates a mapping relationship between each DRB in the at least one DRB and one or more QoS flows in the at least one QoS flow.

17. A communications device, characterized by Comprising: a memory, configured to store instructions; a processor, configured to invoke and run the instructions from the memory, so that the communication apparatus performs the method in any one of claims 1-6.

18. A communications device, characterized by Comprising: a memory, configured to store instructions; a processor, configured to invoke and run the instructions from the memory, so that the communication apparatus performs the method in claim 7 or 8.

19. A communication system, characterized by The communication apparatus in any one of claims 9-14 or 17 and the communication apparatus in any one of claims 15-16 or 18.

20. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, when the instructions are invoked and executed on a computer, causing the computer to perform the method in any one of claims 1-8.

21. A computer program product, characterised in that, The computer program product, when running on a computer, causes the computer to perform the method in any one of claims 1-8.

Images