Communication method and related equipment

Abstract

The invention provides a communication method and related equipment. The communication method is suitable for a target DU, and the method is applied to an LTM switching scene. The method comprises the following steps: receiving a first request message from a CU, wherein the first request message is used for requesting a target DU to provide first configuration; and sending a first response message to the CU, wherein the first response message comprises the first configuration. The first configuration comprises a period P, P cannot be exactly divided by N, N is the period of the wireless frame, and P and N are positive integers greater than or equal to 1. The first configuration is used for determining a first target time domain position, and the first target time domain position is used for communicating with a terminal device. In the method, a target DU sends a period P which cannot be exactly divided by a period N of a wireless frame to a CU, so that a terminal device receives the period P, and after the terminal device is switched to the target DU, the target DU determines a first target time domain position for communicating with the terminal device, thereby supporting data transmission of a service of a specific period.

Description

Technical Field

[0001] The present application relates to the field of communications, and more specifically, to a communication method, a communication device, a communication system, a computer program product, a computer-readable storage medium, and a chip. Background Art

[0002] In the fifth generation mobile communication technology (5G), the movement of the terminal device triggers a handover. The basic goal of the handover is to switch the terminal device to a neighboring cell with better signal quality before the signal quality of the terminal device's service cell becomes incapable of communication, thereby providing continuous and uninterrupted communication services and effectively preventing dropped calls due to the deterioration of the service cell signal quality. In the 5G wireless access network (RAN) architecture, the base station includes a distributed unit (DU) and a central unit (CU). Among them, the DU is responsible for processing physical layer functions and layer 2 functions with real-time requirements, such as processing radio link control (RLC), medium access control (MAC) and physical layer (PHY) layer functions. The CU is responsible for non-real-time wireless high-level protocol stack functions, such as processing service data adaptation protocol (SDAP), radio resource control (RRC), packet data convergence protocol (PDCP) and other functions. CU and DU communicate through the F1 interface, and the maximum transmission delay is about 3ms to 10ms. In layer 1 / layer 2 triggered mobility (LTM) switching, DU determines whether to initiate switching based on the measurement results of the terminal device, and sends the switching command directly to the terminal device, thereby reducing the interaction between CU and DU and reducing the switching delay. However, in the LTM switching scenario, there are problems when the terminal device transmits data of a specific period of service after switching from the source DU to the target DU.

[0003] Therefore, how to support data transmission of services with a specific period in the LTM switching scenario becomes an urgent problem to be solved. Summary of the invention

[0004] The present application provides a communication method, a communication device, a communication system, a computer program product, a computer-readable storage medium and a chip, which support data transmission of services of a specific period in an LTM switching scenario.

[0005] In the first aspect, a communication method is provided. The method is executed by a target DU, and the method is applied to an LTM switching scenario. The method includes: receiving a first request message from a CU, the first request message being used to request the target DU to provide a first configuration; sending a first response message to the CU, the first response message including the first configuration. The first configuration includes a period P, P cannot be divided by N, N is the period of the wireless frame, and P and N are positive integers greater than or equal to 1. The first configuration is used to determine a first target time domain position, and the first target time domain position is used to communicate with a terminal device.

[0006] In an embodiment of the present application, the target DU sends a period P that cannot be divided by the period N of the wireless frame to the CU, so that the terminal device receives the period P. After the terminal device switches to the target DU, the target DU determines the target time domain position for communicating with the terminal device, thereby supporting the transmission of data of services of a specific period.

[0007] In combination with the first aspect, in some implementations of the first aspect, the first configuration also includes a first reference system frame number (SFN) and a first bias, and the period P, the first reference SFN and the first bias are used to determine the first target time domain position.

[0008] In an embodiment of the present application, the target DU carries a first reference SFN and a first bias in a first configuration, so that the terminal device receives the first reference SFN and the first bias. After the terminal device switches to the target DU, the target DU determines the target time domain position for communicating with the terminal device according to the period P, the first reference SFN and the first bias, thereby supporting the transmission of data of services of a specific period.

[0009] In combination with the first aspect, in some implementations of the first aspect, before sending a first response message to the CU, a first reference SFN is determined according to a first time period. The first reference SFN does not belong to an SFN within the first time period. The start time of the first time period is the time when the first request message is received, and the duration of the first time period is less than or equal to N / 2.

[0010] In an embodiment of the present application, the target DU determines the first reference SFN based on the first time period, so that the starting point of the count of the target DU and the terminal device is aligned, thereby determining the number of wireless frame cycles that have passed during the time period from the target DU sending the first reference SFN to the terminal device accessing the target cell.

[0011] In combination with the first aspect, in certain implementations of the first aspect, before sending a first response message to the CU, time period information is received from the CU, where the time period information is used to indicate a first time period, and the first time period includes an expected sending time period of the first configuration or an expected receiving time period of the first configuration; based on the first time period, a first reference SFN is determined, and the first reference SFN does not belong to the SFN within the first time period.

[0012] In an embodiment of the present application, the target DU receives time period information from the CU, thereby determining the first reference SFN according to the expected sending time period or the expected receiving time period of the first configuration, thereby avoiding errors in the terminal device when counting according to the first reference SFN.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the first candidate value set includes a first reference SFN and a second reference SFN, the first reference SFN and the second reference SFN are before a first time, the first reference SFN is closer to the first time than the second reference SFN, the first time is the time when the first request message is received, or the first time is within the expected sending time period of the first response message.

[0014] In an embodiment of the present application, the target DU uses the time of receiving the first request message or the expected sending time period of the first response message as the reference time, and uses the reference SFN closest to the reference time before the reference time as the first reference SFN, thereby avoiding errors in the terminal device when counting according to the first reference SFN.

[0015] In combination with the first aspect, in certain implementations of the first aspect, a first count value is received from the CU, the first count value is used to determine the number K1 of wireless frame periods, the number K1 is counted from the time corresponding to a third reference SFN, the third reference SFN is used by the source DU to determine the second target time domain position, K1 is an integer greater than or equal to 0; according to the first count value, a first reference SFN and a first bias are determined, the period P, the first reference SFN and the first bias are used to determine the first target time domain position, the first target time domain position is the same as the second target time domain position; the first reference SFN and the first bias are sent to the CU.

[0016] In an embodiment of the present application, the target DU determines a first reference SFN and a first offset based on a first count value from the CU, and sends them to the CU, so that the terminal device receives the first reference SFN and the first offset, thereby aligning the configuration of the target DU and the terminal device.

[0017] In combination with the first aspect, in certain implementations of the first aspect, synchronization information of a source DU from a CU is received, and the synchronization information is used for frame synchronization and subframe synchronization between the source DU and the target DU; a first reference SFN and / or the first bias is determined based on the synchronization information and a first count value.

[0018] In an embodiment of the present application, the target DU determines the time domain resource positions corresponding to the source DU and the target DU within the period of the current wireless frame based on the synchronization information of the source DU and the first count value, thereby facilitating determination of the first reference SFN and / or the first offset value.

[0019] In combination with the first aspect, in certain implementations of the first aspect, after the terminal device switches from the source DU to the target DU, a first target SFN and a first target subframe number are determined, and the first target SFN and the first target subframe number are the first target time domain position.

[0020] In an embodiment of the present application, after establishing a connection with the terminal device, the target DU determines a first target time domain position, thereby supporting the transmission of data of a service of a specific period through the first target time domain position.

[0021] In combination with the first aspect, in some implementations of the first aspect, the first target SFN and the first target subframe number satisfy the following formula:

[0022] (Second count value × N + first target SFN × M + first target subframe number) modulo period P = (first reference SFN × M + first offset) modulo period P. Wherein, modulo is a modular operation, and M is the duration of a radio frame. The second count value is used to determine the number K2 of radio frame periods, and the number K2 is counted from the time corresponding to the first reference SFN. The period P, the first reference SFN and the first offset are used to determine the first target time domain position, and K2 is an integer greater than or equal to 0.

[0023] In the embodiment of the present application, the target DU determines the first target time domain position according to the period P, the first reference SFN, the first offset and the second count value, so as to support the transmission of data of the service of a specific period through the time domain position.

[0024] In the second aspect, a communication method is provided. The method is executed by the source DU, and the method is applied to the LTM switching scenario. The method includes: sending auxiliary information to the target DU through the CU, the auxiliary information is used by the target DU to determine the first target time domain position, and the first target time domain position is used to communicate with the terminal device; receiving an RRC reconfiguration message from the CU, the RRC reconfiguration message includes a period P, and the period P is used by the terminal device to determine the first target time domain position, P cannot be divided by N, N is the period of the wireless frame, and P and N are positive integers greater than or equal to 1; sending an RRC reconfiguration message to the terminal device.

[0025] In an embodiment of the present application, the source DU receives a period P from the CU that cannot be divided by the period N of the wireless frame, and sends it to the terminal device, so that the terminal device receives the period P, and after the terminal device switches to the target DU, determines the first target time domain position according to the period P, thereby supporting the transmission of data of services of a specific period.

[0026] In combination with the second aspect, in certain implementations of the second aspect, the RRC reconfiguration message also includes a first reference SFN and a first offset, and the period P, the first reference SFN and the first offset are used by the terminal device to determine the first target time domain position.

[0027] In an embodiment of the present application, the RRC reconfiguration message includes a first reference SFN and a first bias, so that the terminal device receives the first reference SFN and the first bias, and after the terminal device switches to the target DU, the first target time domain position is determined according to the period P, the first reference SFN and the first bias, thereby supporting the transmission of data of services of a specific period.

[0028] In conjunction with the second aspect, in some implementations of the second aspect, the auxiliary information includes time period information, the time period information includes a first time period, the first time period includes an expected sending time period for sending a first configuration to a terminal device or an expected receiving time period for the terminal device to receive the first configuration. The first configuration includes a period P, a first reference SFN, and a first offset.

[0029] In an embodiment of the present application, the source DU sends a first configured expected sending time period or expected receiving time period to the target DU through the CU, thereby facilitating the target DU to determine the first reference SFN, and further facilitating the alignment configuration of the target DU and the terminal device.

[0030] In combination with the second aspect, in certain implementations of the second aspect, an RRC reconfiguration message is sent to the terminal device within a first time period.

[0031] In combination with the second aspect, in certain implementations of the second aspect, a measurement report is received from a terminal device, the measurement report including a measurement result of a target cell; an LTM cell switching command is sent to the terminal device, the LTM cell switching command instructing the terminal device to switch to a target cell, the target cell belonging to a target DU.

[0032] In an embodiment of the present application, the source DU executes a switching decision based on a measurement report from the terminal device, thereby sending an LTM cell switching command to the terminal device, instructing the terminal device to switch to the target cell.

[0033] In combination with the second aspect, in certain implementations of the second aspect, a first count value is sent to the target DU through the CU, and the first count value is used to determine the number K1 of the wireless frame period, and the number K1 starts counting from the time corresponding to the third reference SFN, and the third reference SFN is used by the source DU to determine the second target time domain position, and K1 is an integer greater than or equal to 0; the first reference SFN and the first bias are received from the target DU through the CU, and the period P, the first reference SFN and the first bias are used to determine the first target time domain position, and the first target time domain position is the same as the second target time domain position; the first reference SFN and the first bias are sent to the terminal device.

[0034] In an embodiment of the present application, the source DU sends a first count value to the CU, so that the target DU determines a first reference SFN and a first bias according to the first count value, so that the terminal device receives the first reference SFN and the first bias, and further determines the first target time domain position.

[0035] In combination with the second aspect, in some implementations of the second aspect, the auxiliary information includes synchronization information, and the synchronization information is used for frame synchronization and subframe synchronization between the source DU and the target DU.

[0036] In an embodiment of the present application, the source DU sends synchronization information to the target DU through the CU, thereby facilitating the target DU to determine the first reference SFN, and further facilitating the alignment configuration of the target DU and the terminal device.

[0037] In combination with the second aspect, in certain implementations of the second aspect, a measurement report from a terminal device is received, the measurement report including a measurement result of a target cell; and an LTM cell switching command is sent to the terminal device. The LTM cell switching command includes a first reference SFN and a first offset. The LTM cell switching command instructs the terminal device to switch to a target cell, the target cell belonging to a target DU.

[0038] In an embodiment of the present application, the source DU carries the first reference SFN and the first offset in the LTM cell switching command and sends it to the terminal device, so that after switching to the target DU, the terminal device determines the first target time domain position according to the period P, the first reference SFN and the first offset, thereby supporting the transmission of data of services of a specific period.

[0039] In the third aspect, a communication method is provided. The method is executed by a terminal device, or by a component of the terminal device (such as a processor, a chip, or a chip system, etc.), and the method is applied to an LTM switching scenario. The method includes: receiving an RRC reconfiguration message from a source DU, the RRC reconfiguration message includes the configuration of a target cell, the configuration of the target cell includes a period P, the target cell belongs to a target DU, P cannot be divided by N, N is the period of a wireless frame, and P and N are positive integers greater than or equal to 1; receiving an LTM cell switching command from a source DU, the LTM cell switching command instructing the terminal device to switch to a target cell; determining a first target time domain position according to the configuration of the target cell, and the first target time domain position is used to communicate with the target DU.

[0040] In an embodiment of the present application, the terminal device receives a period P that cannot be divided by the period N of the wireless frame, and determines the first target time domain position for communicating with the target DU based on the period P, thereby supporting the transmission of data of a service of a specific period.

[0041] In combination with the second aspect, in certain implementations of the second aspect, the configuration of the target cell also includes a first reference system frame number SFN and a first offset, and the period P, the first reference SFN and the first offset are used to determine the first target time domain position.

[0042] In an embodiment of the present application, the terminal device receives the first reference SFN and the first bias, thereby determining the target time domain position for communicating with the terminal device based on the period P, the first reference SFN and the first bias, thereby supporting the transmission of data of services of a specific period.

[0043] In combination with the second aspect, in certain implementations of the second aspect, the first target time domain position is determined according to the configuration of the target cell and the reception time of the RRC reconfiguration message.

[0044] In an embodiment of the present application, the terminal device determines the starting point for counting the number of wireless frame periods and starts counting based on the first reference SFN and the reception time of the RRC reconfiguration message, thereby determining the first target time domain position based on the count value, period P, the first reference SFN and the first offset.

[0045] In combination with the second aspect, in certain implementations of the second aspect, the LTM cell switching command further includes a first reference SFN and a first offset, and the period P, the first reference SFN and the first offset are used to determine the first target time domain position.

[0046] In an embodiment of the present application, the terminal device receives the first reference SFN and the first bias, thereby determining the target time domain position for communicating with the terminal device based on the period P, the first reference SFN and the first bias, thereby supporting the transmission of data of services of a specific period.

[0047] In combination with the second aspect, in certain implementations of the second aspect, the first target time domain position is determined according to the configuration of the target cell, the first reference system frame number SFN, the first offset, and the reception time of the LTM cell switching command.

[0048] In an embodiment of the present application, the terminal device determines the starting point for counting the number of wireless frame periods and starts counting based on the first reference SFN and the reception time of the RRC reconfiguration message, thereby determining the first target time domain position based on the count value, period P, the first reference SFN and the first offset.

[0049] In combination with the second aspect, in some implementations of the second aspect, the first time domain position includes a first target SFN and a first target subframe number, and the first target SFN and the first target subframe number satisfy the following formula:

[0050] (third count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P, where modulo is a modular operation and M is the duration of a radio frame. The third count value is used to determine the number K3 of radio frame periods, which is counted from the time corresponding to the first reference SFN, and K3 is an integer greater than or equal to 0.

[0051] In an embodiment of the present application, the terminal device determines a first target time domain position based on the period P, the first reference SFN, the first offset and the third count value, thereby supporting the transmission of data of a service of a specific period through the time domain position.

[0052] In combination with the third aspect, in certain implementations of the third aspect, a measurement report is sent to the source DU, where the measurement report includes a measurement result of the target cell.

[0053] In an embodiment of the present application, the terminal device sends a measurement report to the source DU, thereby receiving an LTM cell switching command, and then switching to the target cell.

[0054] In a fourth aspect, a communication device is provided, wherein the communication device comprises a module for executing the method as described in any possible implementation of the first to third aspects and the first to third aspects.

[0055] In a fifth aspect, a communication device is provided. The communication device includes: at least one processor and a communication interface, the communication interface is used for the communication device to exchange information with other communication devices, and when the program instructions are executed in the at least one processor, the communication device executes the method described in the first aspect or any possible implementation of the first aspect.

[0056] In a sixth aspect, a communication device is provided. The communication device includes: at least one processor and a communication interface, the communication interface is used for the communication device to exchange information with other communication devices, and when the program instructions are executed in the at least one processor, the communication device executes the method described in the second aspect or any possible implementation of the second aspect.

[0057] In a seventh aspect, a communication device is provided. The communication device includes: at least one processor and a communication interface, the communication interface is used for the communication device to exchange information with other communication devices, and when the program instructions are executed in the at least one processor, the communication device executes the method described in the third aspect or any possible implementation of the third aspect.

[0058] In an eighth aspect, a communication system is provided, which includes the communication device according to the fifth aspect, the communication device according to the sixth aspect, and the communication device according to the seventh aspect.

[0059] In a ninth aspect, a computer program product is provided, wherein the computer program product comprises program instructions, and when the program instructions are executed, the method as described in the first to third aspects and any possible implementation of the first to third aspects is executed.

[0060] In a tenth aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores a program code for execution by a device, and when the program code is executed, the method described in any possible implementation of the first to third aspects and the first to third aspects is executed.

[0061] In an eleventh aspect, a chip is provided, which includes at least one processor, and when a program instruction is executed by the at least one processor, the method described in the first to third aspects and any possible implementation of the first to third aspects is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1It is a schematic architecture diagram of the 5G system.

[0063] Figure 2 It is a schematic architecture diagram of a communication system according to an embodiment of the present application.

[0064] Figure 3 It is a schematic diagram of the period of a wireless frame according to an embodiment of the present application.

[0065] Figure 4 It is a schematic flow chart of LTM switching.

[0066] Figure 5 It is a schematic flow chart of a communication method according to an embodiment of the present application.

[0067] Figure 6 It is a schematic flowchart of a communication method according to another embodiment of the present application.

[0068] Figure 7 It is a schematic flowchart of a communication method according to another embodiment of the present application.

[0069] Figure 8 It is a schematic diagram of the structure of a communication device according to an embodiment of the present application.

[0070] Fig. 9 It is a structural diagram of a communication device according to another embodiment of the present application.

[0071] Fig.10 It is a structural diagram of a communication device according to another embodiment of the present application. DETAILED DESCRIPTION

[0072] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0073] The technical solutions of the embodiments of the present application can be applied to various communication systems, for example: global system for mobile communications (GSM) system, code division multiple access (CDMA) system, wideband code division multiple access (WCDMA) system, general packet radio service (GPRS), long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD), universal mobile telecommunication system (UMTS), worldwide interoperability for microwave access (WiMAX) communication system, fourth generation (4G) system, fifth generation (5G) system or new radio (NR), etc.

[0074] The terminal device is a device with wireless transceiver function, which can send signals to the network device or receive signals from the network device. The terminal can refer to an access terminal, a user unit, a user station, a mobile station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a user equipment (UE), a wireless communication device, a user agent or a user device. The user equipment can also be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal in a 5G network or any form of user equipment in a future network, etc., and the embodiments of the present application are not limited to this.

[0075] The network device in the embodiment of the present application may be a device for communicating with a terminal, and is used to access the terminal to a radio access network (RAN). The network device may also be sometimes referred to as an access network device, an access network node, or a base station. It is understandable that in systems using different wireless access technologies, the names of devices having base station functions may be different. For the convenience of description, the embodiments of the present application collectively refer to devices that provide wireless communication access functions for terminals as network devices. The network equipment may be a base transceiver station (BTS) in a global system for mobile communications (GSM) system or a code division multiple access (CDMA) system, a base station (NodeB, NB) in a wideband code division multiple access (WCDMA) system, an evolved NodeB (eNB or eNodeB) in an LTE system, a base station (gNodeB, gNB) in NR, a next generation evolved NodeB (ng-eNB) or a transmission receiving point / transmission reception point (TRP), a base station subsequently evolved by the third generation partnership project (3GPP), an access node, a wireless relay node, a wireless backhaul node in a wireless network communication technology (WiFi) system, etc., and a cloud radio access network (cloud radio access The network device may be a wireless controller in a CRAN (Cran) scenario, or the network device may be a relay station, an access point, a vehicle-mounted device, a wearable device, a network device in a 5G network, or a network device in a future evolved PLMN network, one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system, or a network node constituting a next generation base station node (next generation Node Base station, gNB) or a transmission point, such as a baseband unit (baseband unit, BBU), or a distributed unit (distributed unit, DU), a centralized unit (central unit, CU), etc., and the embodiments of the present application are not limited.

[0076] In an embodiment of the present application, a terminal or network device includes a hardware layer, an operating system layer running on the hardware layer, and an application layer running on the operating system layer. The hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and a memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through a process, such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a windows operating system. The application layer includes applications such as a browser, an address book, a word processing software, and an instant messaging software. In addition, the embodiment of the present application does not specifically limit the specific structure of the execution subject of the method provided in the embodiment of the present application, as long as it can communicate according to the method provided in the embodiment of the present application by running a program that records the code of the method provided in the embodiment of the present application, for example, the execution subject of the method provided in the embodiment of the present application can be a terminal or a network device, or a functional module in a terminal or a network device that can call and execute a program, such as a chip or a processor.

[0077] In addition, various aspects or features of the present application may be implemented as methods, apparatus, or articles of manufacture using standard programming and / or engineering techniques. For example, computer readable media may include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes, etc.), optical disks (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards, and flash memory devices (e.g., erasable programmable read-only memories (EPROMs), cards, sticks, or key drives, etc.). In addition, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data.

[0078] To facilitate understanding of the embodiments of the present application, several terms involved in the present application are first briefly explained.

[0079] 1. Wireless frame

[0080] In mobile communications, data is transmitted on a wireless network in units of radio frames. That is, a radio frame is a time unit for data transmission. A radio frame may include at least one subframe, each subframe may include at least one slot, and each slot may include at least one symbol. When the sub-carrier space (SCS) is 30 kilohertz (kHz), a radio frame may include 10 subframes, each subframe may include 2 slots, and each slot may include 14 symbols. When the duration of a radio frame is 10 milliseconds (ms), the duration of each subframe is 1ms, and the duration of each slot is 0.5ms, so that different subframes can be allocated to the data of multiple users within 1 second (s) to transmit data. The value range of the system frame number (SFN) of a radio frame can be 0 to 1023. When the SFN of a radio frame is 1023, the SFN of the next radio frame of the radio frame can be 0, thereby realizing cyclic value taking.

[0081] 2. Switch

[0082] In the 5G system, the terminal device can trigger a handover due to mobility in the RRC connected state. The basic goal of the handover is to switch the terminal device to a neighboring cell with better signal quality before the signal quality of the serving cell becomes incapable of communication, thereby providing continuous and uninterrupted communication services and effectively preventing dropped calls due to the deterioration of the signal quality of the serving cell. Layer 3 (L3) handover means that the CU can receive a measurement report from the DU and determine whether to initiate a handover based on the measurement report. The measurement report is used to indicate the measurement results of the terminal device. For example, when the signal quality of the serving cell is poor, the CU can send a handover command to the DU, and the DU sends the handover command to the terminal device to achieve handover. Since data is transmitted between the CU and the DU through the F1 interface, there is a certain handover delay. LTM handover means that the handover decision is sent from the CU to the DU, thereby reducing the F1 interaction between the CU and the DU. That is, the DU can determine whether to initiate a handover based on the measurement report of the terminal device and send the handover command directly to the terminal device.

[0083] 3. Discontinuous reception (DRX)

[0084] DRX can be used for energy saving of terminal devices. The terminal device does not need to monitor the physical downlink control channel (PDCCH) all the time, but monitors the PDCCH during a specific activation time. During the inactive time, the terminal device is in sleep mode. The terminal device in sleep mode does not receive data from the PDCCH, but can receive data from other physical channels, such as the physical downlink shared channel (PDSCH), acknowledgment (ACK) / negative acknowledgment (NACK), etc. For example, in semi-persistent scheduling (SPS) scheduling, a terminal device in sleep period can receive PDSCH data sent on a periodically configured downlink subframe. At the same time, DRX also needs to adapt to the service cycle to avoid the terminal device being in an inactive time when the service data arrives, thereby affecting the transmission of the service data.

[0085] 4. Configured grant (CG)

[0086] CG is used for ultra-reliable and low latency communications (URLLC). The terminal device can send data directly without receiving PDCCH scheduling before uplink transmission, thereby reducing transmission latency. Similar to DRX, CG also needs to adapt to the service cycle to avoid affecting the transmission of service data.

[0087] Figure 1 It is a schematic architecture diagram of the 5G system. Figure 1 The 5G system 100 in the embodiment includes a 5G core network (5G core, 5GC) and a 5G radio access network (next generation radio access network, NG RAN). Among them, the 5GC may include at least one access and mobility management function (Access and Mobility Management Function, AMF) network element / user plane function (user plane function, UPF) network element. The NG RAN includes at least one gNB and / or at least one ng-eNB.

[0088] 5GC can be used to implement functions such as registration, connection, and session management. 5GC can also include authentication server function (AUSF) network element, network exposure function (NEF) network element, policy control function (PCF) network element, unified data management (UDM) network element, unified data repository (UDR) network element, network storage function (NRF) network element, application function (AF) network element, session management function module (SMF) network element, etc.

[0089] Among them, the AMF network element mainly performs functions such as mobility management and access authentication / authorization, and can also transmit user policies between terminal devices and PCF network elements. The UPF network element can serve as the interface UPF with the data network to implement functions such as user plane data forwarding, session / flow-level billing statistics, and bandwidth limitation. The AUSF network element can be used to authenticate users to determine whether users or devices are allowed to access the network. The NEF network element can expose the services and capabilities of 3GPP network functions to the AF network element, and can also allow AF to provide information to the 3GPP network function. The PCF network element can be used for policy management of billing policies and quality of service (QoS) policies. The UDM network element can be responsible for managing functions such as subscription data and user access authorization. The UDR network element can be responsible for the storage and access functions of subscription data, policy data, application data, and other types of data. The NRF network element can be used to provide network element discovery functions, and provide network element information corresponding to the network element type based on requests from other network elements. The NRF network element can also provide network element management services, such as network element registration, update, deregistration, and network element status subscription and push. AF network elements can be used to convey the requirements of the application side to the network side. SMF network elements can implement session management functions such as allocation of Internet Protocol (IP) addresses of terminal devices, selection of UPF network elements, billing and QoS policy control.

[0090] Each gNB can provide the termination point of the NR user plane and control plane protocols. Each ng-eNB can provide the termination point of the user plane and control plane protocol stack of the evolved UMTS terrestrial radio access network (E-UTRAN). Each gNB is connected to each other, each gNB is connected to the ng-eNB, and each ng-eNB is connected to the ng-eNB through the Xn interface. Each gNB is connected to the 5GC through the NG interface. Specifically, each gNB is connected to the AMF through the NG-C interface, and each gNB is connected to the UPF through the NR-U interface. Similarly, each ng-eNB is connected to the 5GC through the NG interface. Specifically, each ng-eNB is connected to the AMF through the NG-C interface, and each ng-eNB is connected to the UPF through the NR-U interface.

[0091] Figure 2 It is a schematic structural block diagram of the communication system provided in an embodiment of the present application. Figure 2 The communication system 200 in FIG. 2 includes a source DU 201 , a terminal device 202 , a target DU 203 , and a CU 204 .

[0092] Among them, the source DU 201 and the target DU 203 are responsible for processing physical layer functions and layer 2 (layer 2, L2) functions with real-time requirements, such as processing RLC, MAC and PHY layer functions. CU 204 is responsible for non-real-time wireless high-level protocol stack functions, such as processing SDAP, RRC, PDCP and other functions. At least two of the source DU 201, the target DU 203 and the CU 204 belong to the same network device, or belong to different network devices, and the embodiments of the present application are not limited to this. That is, the source DU 201 and the target DU 203 belong to the same network device, or belong to different network devices. The source DU 201 and the CU 204 belong to the same network device, or belong to different network devices. The target DU 203 and the CU 204 belong to the same network device, or belong to different network devices. The network device is Figure 1 The gNB or ng-eNB in ​​the network.

[0093] The source DU 201 communicates with the target DU 203 through the CU 204. When the source DU 201, the target DU 203 and the CU 204 belong to the same network device, the source DU 201 sends data to the CU 204 through the F1 interface, and the CU 204 sends data to the target DU 203 through the F1 interface. When the source DU 201 and the target DU 203 belong to different network devices, the source DU 201 sends data to the CU of the network device where the source DU 201 is located, the CU of the network device where the source DU 201 is located sends data to the CU of the network device where the target DU 203 is located, and the CU of the network device where the target DU 203 is located sends data to the target DU 203, thereby realizing communication between the source DU 201 and the target DU 203. The CU 204 is the CU of the network device where the source DU 201 is located, or the CU 204 is the CU of the network device where the target DU 203 is located.

[0094] The terminal device 202 is connected to the source DU 201. That is, the terminal device 202 accesses the source cell, which belongs to the source DU 201. The terminal device 202 also accesses the target cell after receiving the handover command. The target cell belongs to the target DU 203. That is, the terminal device 202 is connected to the target DU 203. The handover command is an LTM cell handover command, which includes the identification information of the target cell.

[0095] In some embodiments, the period of the radio frame of the source DU 201 and the period of the radio frame of the target DU 203 are as follows: Figure 3 shown.

[0096] Figure 3 Schematic diagram of the period of the wireless frame provided in the embodiment of the present application. Figure 3 As shown, the radio frame periods of the source DU 201 and the target DU 203 are the same. For example, a radio frame period includes 1024 radio frames, and the SFNs of the 1024 radio frames are numbered sequentially from 0 to 1023. The radio frame period is 1024*10=10240ms. At the same time, the SFNs corresponding to the source DU 201 and the target DU 203 may be the same or different. For example, at the same time, the SFN corresponding to the source DU 201 is 2, and the SFN corresponding to the target DU 203 is 0.

[0097] When the service cycle is divisible by the radio frame cycle, the SFN corresponding to the service is the same in each radio frame cycle. When the service cycle is not divisible by the radio frame cycle, the SFN corresponding to the service is different in different radio frame cycles. The SFN corresponding to the service is the SFN used to transmit the data of the service.

[0098] For example, assuming that the service cycle is 10240ms, the data of the service can be transmitted in each radio frame cycle through a radio frame with SFN 0. Assuming that the service cycle is 10230ms, the data of the service can be transmitted in the first radio frame cycle through radio frames with SFN 0 and SFN 1023, but in the second radio frame cycle, the data of the service needs to be transmitted in a radio frame with SFN 1022.

[0099] When the period of a service cannot be divided evenly by the period of a wireless frame, since the SFN corresponding to the service is different in different periods of wireless frames, after the terminal device switches to the target cell, the target DU cannot determine the time domain position corresponding to the service, resulting in problems in transmitting data of a service of a specific period after the terminal device switches to the target DU.

[0100] Figure 4 It is a schematic flow chart of LTM switching. Figure 4 The following steps are included.

[0101] S301, the terminal device sends a measurement report to the source DU. The measurement report includes layer 3 (layer 3, L3) measurement results, and specifically may include neighboring cell measurement results. Neighboring cells refer to cells that the terminal device may switch to after moving.

[0102] S302, the source DU sends a measurement report to the CU. The source DU sends an uplink (UL) RRC message to the CU. The UL RRC message includes the measurement report.

[0103] S303: The CU decides to initiate LTM configuration according to the measurement report. The CU decides to initiate LTM configuration according to the measurement results of the neighboring cells included in the measurement report.

[0104] S304, CU sends a UE context establishment request message to the candidate DU. The UE context establishment request message may include an identity (ID) of the first candidate cell. It is understandable that the CU also indicates the ID of the source DU. The ID of the source DU is used to request the candidate DU to provide a physical random access channel (PRACH) resource for the source DU.

[0105] S305, the candidate DU sends a UE context establishment response message to the CU. When the candidate DU accepts the request for LTM configuration, the candidate DU sends a UE context establishment response message to the CU. The UE context establishment response message includes at least one of the following information: the lower layer RRC configuration corresponding to the first candidate cell, the transmission configuration indicator (TCI) state configuration and the random access channel (RACH) configuration and the reference signal (RS) configuration.

[0106] S306, the CU sends a UE context modification request message to the source DU, wherein the UE context modification request message includes: the RS configuration of the first candidate cell, the TCI state configuration of the first candidate cell, and the RACH resource configuration of the first candidate cell.

[0107] S307, the source DU sends a UE context modification response message to the CU, wherein the UE context modification response message may include: a channel state information (CSI) resource configuration of the source cell, the CSI resource configuration being used to send a lower layer measurement result of the first candidate cell in the source cell.

[0108] S308, the CU sends a UE context modification request message to the candidate DU. The UE context modification request message may include: the cell ID of the source cell and the RS configuration of the source cell. It should be noted that the candidate cell includes the source cell.

[0109] S309, the candidate DU sends a UE context modification response message to the CU. The UE context modification response message may include: a generated CSI resource configuration. The CSI resource configuration is used to send the CSI of the candidate cell on the first candidate cell.

[0110] S310, the CU sends a downlink (DL) RRC message to the source DU. The DL RRC message may include: an RRC reconfiguration message including an LTM configuration (eg, a lower layer RRC configuration corresponding to the first candidate cell).

[0111] S311, the source DU sends an RRC reconfiguration message to the terminal device.

[0112] S312, the terminal device sends an RRC reconfiguration completion message to the source DU.

[0113] S313, the source DU sends an RRC reconfiguration completion message to the CU. The source DU sends the RRC reconfiguration completion message to the CU via a UL RRC message.

[0114] S314, the terminal device and the candidate DU perform early synchronization. According to the random access resource configuration of the first candidate cell, the terminal device and the candidate DU perform early synchronization on the first candidate cell. Early synchronization includes early uplink synchronization or downlink synchronization.

[0115] S315, the candidate DU sends the timing advance (TA) and associated contention free random access (CFRA) resource information of the first candidate cell to the CU.

[0116] S316, the CU sends the timing advance (TA) and associated contention free random access (CFRA) resource information of the first candidate cell to the source DU.

[0117] Among them, S314, S315, and S316 are optional steps and may not be executed.

[0118] S317, the terminal device sends a measurement report to the source DU. The measurement report includes the lower layer measurement result. The terminal device measures the RS according to the RS configuration, and then sends the measurement result to the source DU according to the CSI resource configuration.

[0119] S318: The source DU decides to perform LTM switching on the candidate cell according to the measurement report.

[0120] S319, the source DU sends an LTM cell switching command to the terminal device. The LTM cell switching command includes the identifier of the target cell, and the LTM cell switching command is used to indicate the first candidate cell as the target cell for switching. The LTM cell switching command may also include beam information of the target cell (for example, TCI state identifier) ​​and timing advance information of the target cell, and the beam information is used for the terminal device to receive downlink control information in a random access-free manner.

[0121] S320, the source DU sends an LTM cell change notification message to the CU. The LTM cell change notification message is used to indicate that an LTM cell switching command has been initiated for the terminal device. The LTM cell change notification message may include a target cell ID and beam information. It can be understood that the target cell is a candidate cell in the above steps.

[0122] S321, the CU sends the target cell ID and beam information to the target DU. It can be understood that the target DU is one of the candidate DUs in the above steps, that is, the DU corresponding to the target cell.

[0123] S322, the target DU detects terminal access. For example, the terminal device accesses the target DU through random access or random access-free mode. If it is a random access-free mode, the target DU sends downlink control information to the terminal device according to the beam information. The random access-free mode is that the terminal device accesses the target cell through PUSCH according to the timing advance information in the LTM cell switching command, rather than accessing the target cell through PRACH.

[0124] S323, the target DU sends a successful access message to the CU. After detecting the access of the terminal device, the target DU sends the successful access message to the CU.

[0125] S324, the CU sends a UE context release command message to the source DU, wherein the UE context release command message is used to release resources of the candidate cells of the source DU.

[0126] S325, the source DU sends a UE context release completion message to the CU.

[0127] In the LTM switching scenario, if the period of the service cannot be divided by the period of the wireless frame, then after the terminal device accesses the target cell, the target DU cannot determine the time domain position corresponding to the service, which causes problems in transmitting data of services with a specific period after the terminal device switches to the target DU.

[0128] Figure 5 It is a schematic flow chart of the communication method provided in an embodiment of the present application. Figure 5 The communication method 400 is composed of Figure 1 or Figure 2 The communication system is implemented in . Figure 5 The following steps are included.

[0129] S401, CU sends a first request message to a candidate DU.

[0130] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, which cannot be divided by N. N is the period of the radio frame, and P and N are positive integers greater than or equal to 1. The first configuration is used to determine a first target time domain position, which is used for the candidate DU to communicate with the terminal device.

[0131] When the first configuration is a CG configuration, the first target time domain position is used for CG transmission. That is, the first target time domain position is a CG time domain resource position. The terminal device and the target DU can communicate at the CG time domain resource position. When the first configuration is a DRX configuration, the first target time domain position is the DRX activation time. During this activation time, the terminal device monitors the PDCCH. When the first configuration is a measurement gap (gap, GAP) configuration, the first target time domain position is used to measure neighboring cells in the GAP.

[0132] In some embodiments, the period of the wireless frame is the product of a first value and the duration of a wireless frame, and the first value is the maximum value of SFN plus 1.

[0133] For example, it is assumed that the value range of SFN is 0 to 1023, that is, the first value is 1024. If the duration of a radio frame is 10 ms, then N is 1024×10 ms=10240 ms.

[0134] In some embodiments, the first request message is a UE context setup request message.

[0135] In some embodiments, the first request message also includes auxiliary information. The auxiliary information is used by the candidate DU to determine the first target time domain position.

[0136] In some embodiments, the auxiliary information includes time period information or synchronization information. The time period information is used to indicate a first time period, and the first time period includes an expected sending time period of a first configuration or an expected receiving time period of a first configuration. The time period includes at least one time slot. The synchronization information is used for frame synchronization and / or subframe synchronization between the source DU and the candidate DU. The synchronization information includes wireless frame synchronization information and / or subframe synchronization information.

[0137] For example, the synchronization information may include a first UTC time and a SFN and a subframe number of a source DU corresponding to the first UTC time. The candidate DU may determine the SFN and the subframe number of the candidate DU corresponding to the first UTC time according to the synchronization information, thereby determining the correspondence between the SFN of the candidate DU and the source DU, and the correspondence between the subframe number of the candidate DU and the source DU.

[0138] S402: The candidate DU sends a first response message to the CU, wherein the first response message includes the first configuration.

[0139] In some embodiments, the first response message is a UE context setup response message.

[0140] After the CU receives the first response message, the CU sends the first configuration to the source DU. Specifically, the CU generates an RRC reconfiguration message and sends a downlink (DL) RRC information transfer message to the source DU. The DL RRC information transfer (DL RRC message transfer) message includes the RRC reconfiguration message. The RRC reconfiguration message includes the first configuration.

[0141] In some embodiments, the first configuration further includes a first reference SFN and a first offset. The period P, the first reference SFN and the first offset are used by the candidate DU to determine the first target time domain position. The first offset is an offset corresponding to the first reference SFN.

[0142] For example, assuming that the SFN of the source DU used to communicate with the terminal device is 600, and the SFN of the candidate DU corresponding to 600 is 598, then the sum of the first reference SFN and the first offset is 598. Assuming that the first reference SFN is 512, the first offset is 86.

[0143] When the time period information is included in the first request message, the candidate DU may determine the first reference SFN according to the first time period included in the time period information. The first reference SFN does not belong to the SFN in the first time period. For specific implementation methods, please refer to the description in step S504.

[0144] When the synchronization information is included in the first request message, the candidate DU can perform frame synchronization and subframe synchronization with the source DU according to the synchronization information, thereby determining the first reference SFN according to the first count value received subsequently. The first count value is used to determine the number K1 of the wireless frame period, and the number K1 starts counting from the time corresponding to the third reference SFN, and K1 is an integer greater than or equal to 0. The initial value of the number K1 corresponds to the third reference SFN, and the initial value is 0, for example. The third reference SFN is used by the source DU to determine the second target time domain position. The second target time domain position is the same as the first target time domain position or matches the service characteristics of the terminal device. For specific implementation methods, please refer to the description in step S612.

[0145] In some embodiments, the candidate DU receives a first count value from the CU after sending the first response message.

[0146] In an embodiment of the present application, the candidate DU sends a period P to the CU, so that the terminal device receives the period P. After the terminal device switches to the candidate DU, the candidate DU and the terminal device can determine the first target time domain position, and then communicate to match the data of the service of a specific period.

[0147] Figure 6 It is a schematic flow chart of the communication method provided in an embodiment of the present application. Figure 6 The communication method 500 is composed of Figure 1 or Figure 2 The communication system is implemented in . Figure 6 The following steps are included.

[0148] S501, CU sends a second request message to a source DU. Correspondingly, the source DU receives the second request message from the CU.

[0149] The second request message is used to request the source DU to provide auxiliary information. The auxiliary information is used by the candidate DU to determine a first target time domain position, and the first target time domain position is used by the candidate DU to communicate with the terminal device.

[0150] Optionally, the auxiliary information includes time period information. The time period information is used to indicate a first time period. The first time period includes an expected sending time period for the source DU to send the first configuration to the terminal device or an expected receiving time period for the terminal device to receive the first configuration. The time period includes at least one time slot. The time period information is similar to the description in step S401.

[0151] In some embodiments, the second request message is a UE context modification request message.

[0152] S502, the source DU sends a second response message to the CU. Correspondingly, the CU receives the second response message from the source DU. The second response message includes the auxiliary information.

[0153] In some embodiments, the second response message is a UE context modification response message.

[0154] When the auxiliary information includes time period information, the time period information includes the start time and duration of the first time period. The start time of the first time period is UTC time. Alternatively, the start time of the first time period is the radio frame information of the source cell. The radio frame information of the source cell includes the SFN and subframe number of the source cell. The source cell belongs to the source DU.

[0155] S503, the CU sends a first request message to the candidate DU. Correspondingly, the candidate DU receives the first request message from the CU.

[0156] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, which cannot be divided by N. N is the period of the radio frame, and P and N are positive integers greater than or equal to 1. The first configuration is used to determine a first target time domain position, which is used for the candidate DU to communicate with the terminal device.

[0157] When the first configuration is a CG configuration, the first target time domain position is used for CG transmission. That is, the first target time domain position is a CG time domain resource position. The terminal device and the target DU can communicate at the CG time domain resource position. When the first configuration is a DRX configuration, the first target time domain position is the DRX activation time. During this activation time, the terminal device monitors the PDCCH. When the first configuration is a measurement interval (GAP) configuration, the first target time domain position is used to measure neighboring cells in the GAP.

[0158] In some embodiments, the period of the wireless frame is the product of a first value and the duration of a wireless frame, and the first value is the maximum value of SFN plus 1.

[0159] In some embodiments, the first request message also includes auxiliary information. The auxiliary information is used by the candidate DU to determine the first target time domain position. The implementation of step S503 is similar to step S401 and will not be repeated here.

[0160] In some embodiments, the first request message is a UE context setup request message.

[0161] S504: The candidate DU sends a first configuration to the CU. Correspondingly, the CU receives the first configuration from the candidate DU.

[0162] The first configuration includes a period P, a first reference SFN and a first offset. The period P, the first reference SFN and the first offset are used to determine the first target time domain position. The first offset is an offset corresponding to the first reference SFN. The implementation of step S504 is similar to step S402.

[0163] In some embodiments, the first configuration is carried in a first response message. The first response message is a UE context setup response message.

[0164] After the candidate DU receives the first request message, the candidate DU determines the first time period according to the time period information in the first request message. The candidate DU also determines the first reference SFN according to the first time period. The first reference SFN does not belong to the SFN in the first time period.

[0165] Optionally, steps S501 and S502 may not be performed. That is, the CU does not need to obtain the time period information from the source DU, and the first request message may not include the time period information.

[0166] When the first request message does not include time period information, the candidate DU determines the first time period by itself. The start time of the first time period is the time when the first request message is received, and the duration of the first time period is less than or equal to N / 2. The first reference SFN does not belong to the SFN within the first time period.

[0167] Exemplarily, the candidate DU determines a first candidate value set. The first candidate value set includes a first reference SFN and a second reference SFN, the first reference SFN and the second reference SFN are before a first time, and the first reference SFN is closer to the first time than the second reference SFN. The first time is the time when the candidate DU receives the first request message, or the first time is within the expected sending time period for the candidate DU to send a first response message, or the first time is within the first time period. The time period includes at least one time slot. Within the expected sending time period, the candidate DU sends the first response message.

[0168] For example, assuming that the first candidate value set includes 0 and 512, if the SFN corresponding to the first time is 600, since 0 and 512 are both before 600, and 512 is closer to 600 than 0, the candidate DU determines that the first reference SFN is 512.

[0169] When the first request message does not include time period information, the candidate DU determines the first reference SFN according to the first time. The first time is the time when the candidate DU receives the first request message, or the first time is within the expected sending time period for the candidate DU to send the first response message. In the expected sending time period, the candidate DU sends the first response message to the CU.

[0170] Optionally, the candidate DU can determine the SFN corresponding to the candidate DU and the source DU according to the first reference SFN and the first offset, and the SFN is used for the source DU to communicate with the terminal device. In other words, the candidate DU can determine the first offset according to the first reference SFN and the SFN.

[0171] For example, assuming that the SFN of the source DU used to communicate with the terminal device is 600, and the SFN of the candidate DU corresponding to 600 is 598, the sum of the first reference SFN and the first offset is 598. Assuming that the first reference SFN is 512, the first offset is 598-512=86.

[0172] Optionally, the candidate DU receives synchronization information from the CU before step S504. The synchronization information is used for frame synchronization and subframe synchronization between the source DU and the candidate DU. The synchronization information includes wireless frame synchronization information and / or subframe synchronization information. After receiving the synchronization information, the candidate DU determines the corresponding relationship between the SFN of the candidate DU and the source DU at the same UTC time, and / or the corresponding relationship between the subframe number of the candidate DU and the source DU at the same UTC time.

[0173] For example, the synchronization information may include a first UTC time and a SFN and a subframe number of a source DU corresponding to the first UTC time. The candidate DU may determine the SFN and the subframe number of the candidate DU corresponding to the first UTC time according to the synchronization information, thereby determining the correspondence between the SFN of the candidate DU and the SFN of the source DU, and the correspondence between the subframe number of the candidate DU and the subframe number of the source DU.

[0174] S505, the CU sends a first configuration to the source DU. Correspondingly, the source DU receives the first configuration. The first configuration includes a period P, a first reference SFN, and a first offset.

[0175] In some embodiments, after receiving the first configuration, the CU generates an RRC reconfiguration message. The RRC reconfiguration message includes the first configuration. The CU also sends a DL RRC information transfer message to the source DU. The DL RRC information transfer message includes the RRC reconfiguration message.

[0176] In some embodiments, the CU receives a first configuration from each candidate DU in at least one candidate DU. The at least one candidate DU includes the candidate DU. The CU also sends the first configuration of each candidate DU to the source DU. Correspondingly, the source DU receives the first configuration of each candidate DU.

[0177] S506, the source DU sends a first configuration to the terminal device. Correspondingly, the terminal device receives the first configuration. The first configuration is a configuration of a candidate cell. The first configuration includes a period P.

[0178] In some embodiments, the source DU sends the first configuration to the terminal device within the first time period. Alternatively, the terminal device receives the first configuration within the first time period.

[0179] In some embodiments, the source DU sends an RRC reconfiguration message to the terminal device, wherein the RRC reconfiguration message includes the configuration of the candidate cell.

[0180] In some embodiments, the configuration of the candidate cell also includes a first reference SFN and a first offset.

[0181] In some embodiments, the source DU receives the first configuration of each candidate DU in at least one candidate DU. The source DU also sends the first configuration of each candidate DU to the terminal device. Correspondingly, the terminal device receives the first configuration of each candidate DU.

[0182] S507, the terminal device sends a configuration completion message to the source DU. Correspondingly, the source DU receives the configuration completion message.

[0183] In some embodiments, the configuration complete message is an RRC reconfiguration complete message.

[0184] S508, the source DU sends a configuration completion message to the CU. Correspondingly, the CU receives the configuration completion message from the source DU.

[0185] In some embodiments, the configuration complete message is an RRC reconfiguration complete message.

[0186] In some embodiments, the source DU sends a UL RRC message to the CU. The UL RRC message includes the RRC reconfiguration complete message.

[0187] S509, the terminal device sends a measurement report to the source DU. Correspondingly, the source DU receives the measurement report from the terminal device.

[0188] The measurement report includes a measurement result of a first candidate cell. The first candidate cell belongs to a candidate DU. The measurement result of the first candidate cell is used to indicate a signal quality of the first candidate cell.

[0189] In some embodiments, the terminal device measures the RS according to the RS configuration, and then sends the measurement result to the source DU according to the CSI resource configuration.

[0190] In some embodiments, before the terminal device sends the measurement report, according to the random access resource configuration of the first candidate cell, the terminal device and the candidate DU perform early synchronization on the first candidate cell. Early synchronization includes early uplink synchronization or downlink synchronization. The candidate DU sends the timing advance (TA) and associated non-contention random access (CFRA) resource information of the first candidate cell to the source DU through the CU.

[0191] In some embodiments, the terminal device sends a measurement report to the first DU. Correspondingly, the first DU receives the measurement report from the terminal device. The first DU is a DU different from the source DU. That is, the terminal device switches from the source DU to the first DU, and after switching to the first DU, sends a measurement report to the first DU. After the terminal device switches to the first DU, the first DU is regarded as the source DU of the terminal device.

[0192] S510: The source DU decides to perform LTM switching according to the measurement report. For example, the source DU decides to perform LTM switching on the first candidate cell.

[0193] S511, the source DU sends an LTM cell switching command to the terminal device. Correspondingly, the terminal device receives the LTM cell switching command.

[0194] The LTM cell switching command indicates a first candidate cell as a target cell for switching. The first candidate cell is the target cell. The LTM cell switching command includes an identifier of the target cell.

[0195] In some embodiments, the LTM cell switching command also includes beam information of the target cell (e.g., time controlled interrupt state (TCI state) identifier) ​​and timing advance information of the target cell. The beam information is used for the terminal device to receive downlink control information in a random access-free manner.

[0196] In some embodiments, the LTM cell switching command is a MAC control element (MAC-CE) message.

[0197] S512: The source DU sends a LTM cell change notification message to the CU. Correspondingly, the CU receives the LTM cell change notification message from the source DU.

[0198] The LTM cell change notification message is used to indicate that an LTM cell handover command has been initiated for the terminal device. The LTM cell change notification message may include a target cell ID and beam information. It can be understood that the target cell is the first candidate cell in the above step.

[0199] S513, the CU sends the target cell ID and beam information to the target DU. Correspondingly, the target DU receives the target cell ID and beam information from the CU.

[0200] It can be understood that the target DU is one of the candidate DUs in the aforementioned steps, that is, the DU corresponding to the target cell.

[0201] Optionally, before step S514, the target DU detects terminal access. For example, the terminal device accesses the target DU through random access or random access-free mode. If it is a random access-free mode, the target DU sends downlink control information to the terminal device according to the beam information. The random access-free mode is that the terminal device accesses the target cell through PUSCH according to the timing advance information in the LTM cell switching command, instead of accessing the target cell through PRACH.

[0202] After detecting the access of the terminal device, the target DU sends the successful access message to the CU.

[0203] After the CU receives the successful access message from the target DU, the CU sends a UE context release command message to the source DU. The UE context release command message is used to release the resources of the candidate cell of the source DU. The source DU sends a UE context release completion message to the CU.

[0204] S514: The terminal device determines the first target time domain position according to the first configuration.

[0205] After accessing the target cell (ie, switching to the target DU), the terminal device applies the first configuration. The first configuration is the configuration of the target cell. The first target time domain position is used to communicate with the target DU.

[0206] In some embodiments, the configuration of the target cell includes a period P, a first reference SFN, and a first offset. The period P, the first reference SFN, and the first offset are used to determine the first target time domain position.

[0207] In some embodiments, the terminal device determines the first target time domain position based on the configuration of the target cell and the reception time of the RRC reconfiguration message.

[0208] Exemplarily, the terminal device determines the third count value according to the first reference SFN and the reception time of the RRC reconfiguration message. The terminal device also determines the first target time domain position according to the third count value, the period P, the first reference SFN and the first offset.

[0209] After the terminal device receives the first configuration, the terminal device determines a first receiving time. The first receiving time is the time when the first configuration is received. In other words, the first receiving time is the time when the RRC reconfiguration message is received.

[0210] In some embodiments, the first receiving time is UTC time. Alternatively, the first receiving time is the SFN, subframe and symbol of the source cell. The source cell belongs to the source DU. The source cell is the current serving cell of the terminal device.

[0211] After the terminal device determines the first receiving time, the terminal device determines a third count value according to the first receiving time and the first reference SFN. The third count value is used to determine the number K3 of the period of the wireless frame, and the number K3 starts counting from the time corresponding to the first reference SFN, and K3 is an integer greater than or equal to 0. The initial value of the number K3 corresponds to the first reference SFN, and the initial value is, for example, 0.

[0212] For example, assuming that the first reference SFN is 512, the number of radio frames that have passed during the period from the first reference SFN to the first SFN after the first reference SFN being 511 is 0, and the third count value is 0. During the period from the first SFN after the first reference SFN being 512 to the second SFN after the first reference SFN being 511, the number of radio frames that have passed is 1, and the third count value is 1, and so on.

[0213] Exemplarily, the first reference SFN is before the first receiving time and is closest to the first receiving time.

[0214] For example, assuming that the first reference SFN is 512, the SFN corresponding to the first receiving time is 600. Before the first receiving time, there are multiple SFNs 512, and the first reference SFN is 512 closest to the first receiving time among the multiple SFNs.

[0215] After the target DU sends the first configuration to the CU, the terminal device may switch to the target cell after at least one wireless frame period. After the terminal device accesses the target cell, the terminal device applies the first configuration, resulting in different understandings of the target time domain position indicated by the first configuration between the terminal device and the target DU, which in turn causes data transmission failure.

[0216] In some embodiments, the first target time domain position includes a first target SFN and a first target subframe number. The first target SFN and the first target subframe number satisfy the following formula:

[0217] (third count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0218] Wherein, N is the period of a radio frame, M is the duration corresponding to a radio frame, and modulo is a modular operation.

[0219] When N is 10240ms and M is 10ms, the above formula is:

[0220] (third count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0221] S515: The target DU determines a first target time domain position according to the first configuration.

[0222] After the terminal device switches to the target DU, the target DU determines a first target time domain position according to the first configuration. The first target time domain position includes a first target SFN and a first target subframe number.

[0223] Optionally, after determining the first reference SFN, the target DU determines a second count value according to the first reference SFN. The second count value is used to determine the number K2 of the period of the wireless frame, and the number K2 starts counting from the time corresponding to the first reference SFN. The initial value of the number K2 corresponds to the first reference SFN, and the initial value is, for example, 0.

[0224] For example, assuming that the first reference SFN is 512, the number of radio frame cycles that have passed during the time from the first reference SFN to the first SFN after the first reference SFN being 511 is 0, and the second count value is 0. During the time from the first SFN after the first reference SFN being 512 to the second SFN after the first reference SFN being 511, the number of radio frame cycles that have passed is 1, and the second count value is 1, and so on.

[0225] After the target DU sends the first configuration to the CU, the terminal device may switch to the target cell after at least one wireless frame period. After the terminal device accesses the target cell, the terminal device applies the first configuration, resulting in different understandings of the target time domain position indicated by the first configuration between the terminal device and the target DU, which in turn causes data transmission failure.

[0226] Optionally, the target DU determines the first target SFN and the first target subframe number according to the first configuration and the second count value.

[0227] In some embodiments, the first target SFN and the first target subframe number satisfy the following formula:

[0228] (second count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0229] Wherein, N is the period of a radio frame, M is the duration corresponding to a radio frame, and modulo is a modular operation.

[0230] When N is 10240ms and M is 10ms, the above formula is:

[0231] (second count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0232] In an embodiment of the present application, the terminal device determines the number of wireless frame cycles that have passed based on the received first configuration and the time of receiving the first configuration, so that after the terminal device switches to the target DU, the target DU and the terminal device determine the first target time domain position based on the first configuration and the number of wireless frame cycles that have passed, and then communicate with the data matching the service of the specific period.

[0233] Figure 7 It is a schematic flow chart of the communication method provided in an embodiment of the present application. Figure 7 The communication method 600 comprises Figure 1 or Figure 2 The communication system is implemented in . Figure 7 The following steps are included.

[0234] S601, CU sends a third request message to a source DU. Correspondingly, the source DU receives the third request message from the CU.

[0235] The third request message is used to request the source DU to provide auxiliary information. The auxiliary information is used by the candidate DU to determine a first target time domain position, and the first target time domain position is used by the candidate DU to communicate with the terminal device.

[0236] Optionally, the auxiliary information includes synchronization information. The synchronization information is used for the source DU and the candidate DU to perform frame synchronization and subframe synchronization. The synchronization information includes wireless frame synchronization information and / or subframe synchronization information. The synchronization information is similar to the description in step S401.

[0237] For example, the synchronization information may include a first UTC time and a SFN and a subframe number of a source DU corresponding to the first UTC time. The candidate DU may determine the SFN and the subframe number of the candidate DU corresponding to the first UTC time according to the synchronization information, thereby determining the correspondence between the SFN of the candidate DU and the source DU, and the correspondence between the subframe number of the candidate DU and the source DU.

[0238] In some embodiments, the third request message is a UE context modification request message.

[0239] S602: The source DU sends third response information to the CU.

[0240] Correspondingly, the CU receives a third response message from the source DU, wherein the third response message includes the auxiliary information.

[0241] In some embodiments, the third response message is a UE context modification response message.

[0242] S603, the CU sends a first request message to the candidate DU. Correspondingly, the candidate DU receives the first request message from the CU.

[0243] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, which cannot be divided by N. N is the period of the radio frame, and P and N are positive integers greater than or equal to 1. The first configuration is used to determine a first target time domain position, which is used for the candidate DU to communicate with the terminal device. The implementation method of step S603 is similar to S401.

[0244] When the first configuration is a CG configuration, the first target time domain position is used for CG transmission. That is, the first target time domain position is a CG time domain resource position. The terminal device and the target DU can communicate at the CG time domain resource position. When the first configuration is a DRX configuration, the first target time domain position is the DRX activation time. During this activation time, the terminal device monitors the PDCCH. When the first configuration is a measurement interval (GAP) configuration, the first target time domain position is used to measure neighboring cells in the GAP.

[0245] In some embodiments, the period of the wireless frame is the product of a first value and the duration of a wireless frame, and the first value is the maximum value of SFN plus 1.

[0246] In some embodiments, the first request message also includes auxiliary information. The auxiliary information is used by the candidate DU to determine the first target time domain position.

[0247] In some embodiments, the first request message is a UE context setup request message.

[0248] S604: The candidate DU sends a first configuration to the CU. Correspondingly, the CU receives the first configuration from the candidate DU.

[0249] The first configuration includes a period P. The period P is used by the terminal device to determine the first target time domain position. The implementation of step S604 is similar to step S402.

[0250] In some embodiments, the first configuration is carried in a first response message. The first response message is a UE context setup response message.

[0251] S605, the CU sends a first configuration to the source DU. Correspondingly, the source DU receives the first configuration. The first configuration includes a period P.

[0252] In some embodiments, after receiving the first configuration, the CU generates an RRC reconfiguration message. The RRC reconfiguration message includes the first configuration. The CU also sends a DL RRC information transfer message to the source DU. The DL RRC information transfer message includes the RRC reconfiguration message.

[0253] In some embodiments, the CU receives a first configuration from each candidate DU in at least one candidate DU. The at least one candidate DU includes the candidate DU. The CU also sends the first configuration of each candidate DU to the source DU. Correspondingly, the source DU receives the first configuration of each candidate DU.

[0254] S606, the source DU sends a first configuration to the terminal device. Correspondingly, the terminal device receives the first configuration. The first configuration is a configuration of a candidate cell. The first configuration includes a period P.

[0255] In some embodiments, the source DU sends an RRC reconfiguration message to the terminal device, wherein the RRC reconfiguration message includes the configuration of the candidate cell.

[0256] In some embodiments, the source DU receives the first configuration of each candidate DU in at least one candidate DU. The source DU also sends the first configuration of each candidate DU to the terminal device. Correspondingly, the terminal device receives the first configuration of each candidate DU.

[0257] S607, the terminal device sends a configuration completion message to the source DU. Correspondingly, the source DU receives the configuration completion message.

[0258] In some embodiments, the configuration complete message is an RRC reconfiguration complete message. The implementation of step S607 is similar to step S507.

[0259] S608, the source DU sends a configuration completion message to the CU. Correspondingly, the CU receives the configuration completion message from the source DU.

[0260] In some embodiments, the configuration complete message is an RRC reconfiguration complete message. The implementation of step S608 is similar to step S508.

[0261] In some embodiments, the source DU sends a UL RRC message to the CU. The UL RRC message includes the RRC reconfiguration complete message.

[0262] S609, the terminal device sends a measurement report to the source DU.

[0263] The measurement report includes a measurement result of the first candidate cell. The first candidate cell belongs to the candidate DU. The measurement result of the first candidate cell is used to indicate the signal quality of the first candidate cell. The implementation method of step S609 is similar to step S509.

[0264] In some embodiments, the terminal device measures the RS according to the RS configuration, and then sends the measurement result to the source DU according to the CSI resource configuration.

[0265] In some embodiments, before the terminal device sends the measurement report, the terminal device and the candidate DU perform early synchronization on the first candidate cell according to the random access resource configuration of the first candidate cell. Early synchronization includes early uplink synchronization or downlink synchronization. The candidate DU sends the TA and CFRA resource information of the first candidate cell to the source DU through the CU.

[0266] In some embodiments, the terminal device sends a measurement report to the first DU. Correspondingly, the first DU receives the measurement report from the terminal device. The first DU is a DU different from the source DU. That is, the terminal device switches from the source DU to the first DU, and after switching to the first DU, sends a measurement report to the first DU. After the terminal device switches to the first DU, the first DU is regarded as the source DU of the terminal device.

[0267] S610: The source DU decides to perform LTM switching according to the measurement report. That is, the source DU decides to perform LTM on the first candidate cell. The implementation of step S610 is similar to step S510.

[0268] S611: The source DU sends a first count value to the CU. Correspondingly, the CU receives the first count value from the source DU.

[0269] The first count value is used to determine the number K1 of the period of the wireless frame, and the number K1 is counted from the time corresponding to the third reference SFN, and K1 is an integer greater than or equal to 0. The initial value of the number K1 corresponds to the third reference SFN, and the initial value is, for example, 0. The third reference SFN is used by the source DU to determine the second target time domain position. The second target time domain position is the same as the first target time domain position or matches the service characteristics of the terminal device.

[0270] In some embodiments, the source DU determines a third reference SFN. The source DU also determines the first count value based on the third reference SFN.

[0271] For example, assuming that the third reference SFN is 512, the number of radio frame cycles that have passed during the time from the third reference SFN to the first SFN after the third reference SFN being 511 is 0, and the first count value is 0. During the time from the first SFN after the third reference SFN being 512 to the second SFN after the third reference SFN being 511, the number of radio frame cycles that have passed is 1, and the first count value is 1, and so on. The manner of determining the first count value is similar to the manner of determining the second count value in step S515.

[0272] Exemplarily, the source DU determines the third reference SFN from at least one candidate value. For example, the source DU uses any one of the at least one candidate value as the third reference SFN.

[0273] Exemplarily, the source DU determines a second candidate value set. The second candidate value set includes a third reference SFN and a fourth reference SFN, the third reference SFN and the fourth reference SFN are before a second time, and the third reference SFN is closer to the second time than the fourth reference SFN. The second time is within an expected sending time period for the source DU to send synchronization information to the CU, or the second time is within an expected receiving time period for the target DU to receive the synchronization information. Within the expected sending time period, the source DU sends synchronization information to the CU. Within the expected receiving time period, the target DU receives the synchronization information. Wherein, the time period includes at least one time slot. Wherein, the time period includes at least one time slot.

[0274] For example, assuming that the second candidate value set includes 0 and 512, if the SFN corresponding to the second time is 600, since 0 and 512 are both before 600, and 512 is closer to 600 than 0, the source DU determines that the third reference SFN is 512.

[0275] S612: The CU sends a first count value to the candidate DU. Correspondingly, the candidate DU receives the first count value from the CU.

[0276] After the candidate DU receives the first count value, the candidate DU determines a first reference SFN and / or a first offset according to the synchronization information and the first count value. The first reference SFN and the first offset are used to determine the first target time domain position. The first offset is an offset corresponding to the first reference SFN.

[0277] Exemplarily, the candidate DU determines the SFN of the source DU in the current wireless frame period according to the synchronization information and the first count value, and the SFN of the source DU is used to determine the time domain position for communicating with the terminal device. The candidate DU determines the SFN of the candidate DU corresponding to the SFN of the source DU according to the synchronization information. The candidate DU determines the first reference SFN and the first offset according to the SFN of the candidate DU. The sum of the first reference SFN and the first offset is the SFN of the candidate DU.

[0278] For example, assuming that in the current wireless frame period, the SFN of the source DU used to communicate with the terminal device is 600, and the SFN of the candidate DU corresponding to 600 is 598, then it can be determined that the first reference SFN is 512 and the first offset is 86.

[0279] Exemplarily, the candidate DU determines a first candidate value set. The first candidate value set includes a first reference SFN and a second reference SFN, the first reference SFN and the second reference SFN are before a third time, and the first reference SFN is closer to the third time than the second reference SFN. The third time is the time when the candidate DU receives the first count value, or the third time is within the expected sending time period for the candidate DU to send the first reference SFN, or the third time is within the expected receiving time period for the terminal device to receive the first reference SFN. Within the expected sending time period, the candidate DU sends the first reference SFN to the CU. Within the expected receiving time period, the terminal device receives the first reference SFN. The time period includes at least one time slot. The specific implementation method is similar to the description in step S504.

[0280] For example, assuming that the first candidate value set includes 0 and 512, if the SFN corresponding to the third time is 600, since 0 and 512 are both before 600, and 512 is closer to 600 than 0, the candidate DU determines that the first reference SFN is 512.

[0281] S613: The candidate DU sends a first reference SFN and a first offset to the CU. Correspondingly, the CU receives the first reference SFN and the first offset from the candidate DU.

[0282] S614, the CU sends a first reference SFN and a first offset to the source DU. Correspondingly, the source DU receives the first reference SFN and the first offset from the CU.

[0283] S615, the source DU sends an LTM cell switching command to the terminal device. Correspondingly, the terminal device receives the LTM cell switching command.

[0284] The LTM cell switching command indicates a first candidate cell as a target cell for switching. The first candidate cell is the target cell. The LTM cell switching command includes an identifier of the target cell.

[0285] In some embodiments, the LTM cell switching command also includes beam information of the target cell (e.g., time controlled interrupt state (TCI state) identifier) ​​and timing advance information of the target cell. The beam information is used for the terminal device to receive downlink control information in a random access-free manner.

[0286] In some embodiments, the LTM cell switching command includes a first reference SFN and a first offset. The period P, the first reference SFN and the first offset are used to determine the first target time domain position.

[0287] In some embodiments, the LTM cell switching command is a MAC-CE message.

[0288] S616, the source DU sends a LTM cell change notification message to the CU. Correspondingly, the CU receives the LTM cell change notification message from the source DU. The implementation of step S616 is similar to step S512.

[0289] The LTM cell change notification message is used to indicate that an LTM cell handover command has been initiated for the terminal device. The LTM cell change notification message may include a target cell ID and beam information. It can be understood that the target cell is the first candidate cell in the above step.

[0290] S617, the CU sends the target cell ID and beam information to the target DU. Correspondingly, the target DU receives the target cell ID and beam information from the CU. The implementation of step S617 is similar to step S513.

[0291] It can be understood that the target DU is one of the candidate DUs in the aforementioned steps, that is, the DU corresponding to the target cell.

[0292] Optionally, before step S618, the target DU detects terminal access. For example, the terminal device accesses the target DU through random access or random access-free mode. If it is a random access-free mode, the target DU sends downlink control information to the terminal device according to the beam information. The random access-free mode is that the terminal device accesses the target cell through PUSCH according to the timing advance information in the LTM cell switching command, instead of accessing the target cell through PRACH.

[0293] After detecting the access of the terminal device, the target DU sends the successful access message to the CU.

[0294] After the CU receives the successful access message from the target DU, the CU sends a UE context release command message to the source DU. The UE context release command message is used to release the resources of the candidate cell of the source DU. The source DU sends a UE context release completion message to the CU.

[0295] S618, the terminal device determines a first target time domain position according to the first configuration, the first reference SFN and the first offset.

[0296] After accessing the target cell (i.e., switching to the target DU), the terminal device determines a first target time domain position according to the first configuration, the first reference SFN, and the first offset. The first target time domain position is used to communicate with the target DU. The first configuration is the configuration of the target cell.

[0297] In some embodiments, the terminal device determines the first target time domain position according to the first configuration, the first reference system frame number SFN, the first offset and the reception time of the LTM cell switching command.

[0298] After the terminal device receives the first reference SFN, the terminal device determines a second receiving time. The second receiving time is the time when the first reference SFN is received. In other words, the second receiving time is the time when the LTM cell switching command is received.

[0299] In some embodiments, the second receiving time is UTC time. Alternatively, the second receiving time is the SFN, subframe and symbol of the source cell. The source cell belongs to the source DU. The source cell is the current serving cell of the terminal device.

[0300] After the terminal device determines the second receiving time, the terminal device determines a third count value according to the second receiving time and the first reference SFN. The third count value is used to determine the number K3 of the period of the wireless frame, and the number K3 starts counting from the time corresponding to the first reference SFN, and K3 is an integer greater than or equal to 0. The initial value of the number K3 corresponds to the first reference SFN, and the initial value is, for example, 0. The manner in which the terminal device determines the third count value is similar to the description in step S514, and will not be repeated here.

[0301] Exemplarily, the first reference SFN is before the second receiving time and is closest to the second receiving time.

[0302] In some embodiments, the first target time domain position includes a first target SFN and a first target subframe number. The first target SFN and the first target subframe number satisfy the following formula:

[0303] (third count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0304] Wherein, N is the period of a radio frame, M is the duration corresponding to a radio frame, and modulo is a modular operation.

[0305] When N is 10240ms and M is 10ms, the above formula is:

[0306] (third count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0307] S619: The target DU determines a first target time domain position according to the first configuration, the first reference SFN and the first offset.

[0308] After the terminal device switches to the target DU, the target DU determines a first target time domain position according to the first configuration, the first reference SFN and the first offset. The first target time domain position includes a first target SFN and a first target subframe number.

[0309] Optionally, after determining the first reference SFN, the target DU determines a second count value according to the first reference SFN. The second count value is used to determine the number K2 of the period of the radio frame, and the number K2 starts counting from the time corresponding to the first reference SFN. The initial value of the number K2 corresponds to the first reference SFN, and the initial value is, for example, 0. The way in which the target DU determines the second count value is similar to the description in step S515, and will not be repeated here.

[0310] In some embodiments, the first target SFN and the first target subframe number satisfy the following formula:

[0311] (second count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0312] Wherein, N is the period of a radio frame, M is the duration corresponding to a radio frame, and modulo is a modular operation.

[0313] When N is 10240ms and M is 10ms, the above formula is:

[0314] (second count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0315] In an embodiment of the present application, the terminal device determines the number of wireless frame cycles that have passed based on the time of the received first reference SFN and the first reference SFN, so that after the terminal device switches to the target DU, the target DU and the terminal device determine the first target time domain position based on the number of wireless frame cycles that have passed, the period P, the first reference SFN and the first bias, and then communicate to match the data of the service of the specific period.

[0316] It is understood that in order to implement the functions in the above embodiments, the terminal device, the source DU, and the target DU include hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0317] Figure 8 , Fig. 9 and Fig.10 The following is a schematic diagram of the structure of possible communication devices provided in the embodiments of the present application. These communication devices are used to implement the functions of the target DU, source DU or terminal device in the above method embodiments, so as to achieve the beneficial effects of the above method embodiments. In the embodiments of the present application, the communication device is as follows Figure 2 The source DU 201 or the target DU 203 shown is also Figure 2 The terminal device 202 is shown.

[0318] like Figure 8 As shown, the communication device 700 includes a receiving unit 710 and a sending unit 720. The communication device 700 is used to implement the above Figure 5 , Figure 6 or Figure 7 The function of the target DU or the source DU in the method embodiment shown in FIG.

[0319] When the communication device 700 is used to implement Figure 5 , Figure 6 or Figure 7 In the method embodiment shown in the figure, the function of the target DU is: the receiving unit 710 is used to receive a first request message from the CU; the sending unit 720 is used to send a first response message to the CU, and the first response message includes a first configuration. Figure 5 , Figure 6 or Figure 7 The first request message, the first response message, and the first configuration are similar and will not be repeated here.

[0320] In some embodiments, when the communication device 700 is used to implement Figure 6 In the method embodiment shown in FIG. 1 , when the target DU functions, the communication device 700 further includes a processing unit. The processing unit is configured to determine a first reference SFN according to the first time period. The first time period, the first reference SFN and Figure 6 The first time period and the first reference SFN are similar and will not be repeated here.

[0321] In some embodiments, when the communication device 700 is used to implement Figure 6 In the method embodiment shown in FIG. 1 , the receiving unit 710 is further configured to receive time period information from the CU. The time period information is Figure 6 The time period information in is similar and will not be repeated here.

[0322] In some embodiments, when the communication device 700 is used to implement Figure 7 When the function of the target DU is used in the method embodiment shown, the communication device 700 also includes a processing unit. The receiving unit 710 is also used to receive a first count value from the CU; the processing unit is also used to determine a first reference SFN and a first offset according to the first count value; the sending unit 720 is also used to send the first reference SFN and the first offset to the CU. The first count value, the first reference SFN and the first offset are Figure 7 The first count value, the first reference SFN and the first offset are similar and will not be described in detail here.

[0323] In some embodiments, when the communication device 700 is used to implement Figure 7 In the method embodiment shown in FIG. 1 , when the target DU is used, the communication device 700 further includes a processing unit. The receiving unit 710 is further configured to receive synchronization information from the CU; the processing unit is further configured to determine the first reference SFN and / or the first offset according to the synchronization information and the first count value. The synchronization information and the first count value are Figure 7 The synchronization information in is similar and will not be repeated here.

[0324] In some embodiments, when the communication device 700 is used to implement Figure 6 or Figure 7 In the method embodiment shown in FIG. 1 , the communication device 700 further includes a processing unit. After the terminal device switches from the source DU to the communication device 700, the processing unit is further configured to determine a first target SFN and a first target subframe number. The first target SFN and the first target subframe number are Figure 6 , Figure 7 The first target SFN and the first target subframe number are similar and will not be repeated here.

[0325] When the communication device 700 is used to implement Figure 6 or Figure 7In the method embodiment shown in the figure, the source DU functions as follows: the sending unit 720 is used to send auxiliary information to the target DU through the CU; the receiving unit 710 is used to receive the RRC reconfiguration message from the CU; the sending unit 720 is also used to send the RRC reconfiguration message to the terminal device. The auxiliary information, the RRC reconfiguration message and Figure 6 , Figure 7 The auxiliary information and RRC reconfiguration message are similar and will not be repeated here.

[0326] In some embodiments, when the communication device 700 is used to implement Figure 6 , Figure 7 In the method embodiment shown in the figure, the source DU functions as follows: the receiving unit 710 is further configured to receive a measurement report from a terminal device; the sending unit 720 is further configured to send an LTM cell switching command to the terminal device. Figure 6 , Figure 7 The measurement report and LTM cell switching command are similar and will not be repeated here.

[0327] In some embodiments, when the communication device 700 is used to implement Figure 7 In the method embodiment shown in the figure, the source DU functions as follows: the sending unit 720 is further used to send a first count value to the target DU through the CU; the receiving unit 710 is further used to receive a first reference SFN and a first offset from the target DU through the CU. The first count value, the first reference SFN and the first offset are Figure 7 The first count value, the first reference SFN and the first offset are similar and will not be described in detail here.

[0328] For more detailed description of the receiving unit 710 and the sending unit 720, refer to Figure 5 , Figure 6 or Figure 7 Related description in the method embodiment shown.

[0329] like Fig. 9 As shown, the communication device 800 includes a transceiver unit 810 and a processing unit 820. The communication device 800 is used to implement the above Figure 6 or Figure 7 The functions of the terminal device in the method embodiment shown in FIG.

[0330] When the communication device 800 is used to implement Figure 6 or Figure 7In the method embodiment shown, the functions of the terminal device are as follows: the transceiver unit 810 is used to receive an RRC reconfiguration message from a source DU, wherein the RRC reconfiguration message includes the configuration of the target cell; the transceiver unit 810 is also used to receive an LTM cell switching command from the source DU; the processing unit 820 is used to determine the first target time domain position according to the configuration of the target cell. The RRC reconfiguration message, the configuration of the target cell, the LTM cell switching command, the first target time domain position and Figure 6 or Figure 7 The description is similar to that in , and will not be repeated here.

[0331] In some embodiments, when the communication device 800 is used to implement Figure 6 The function of the terminal device in the method embodiment shown is: the processing unit 820 is also used to determine the first target time domain position according to the configuration of the target cell and the reception time of the RRC reconfiguration message.

[0332] In some embodiments, when the communication device 800 is used to implement Figure 7 The functions of the terminal device in the method embodiment shown are: the processing unit 820 is also used to determine the first target time domain position according to the configuration of the target cell, the first reference SFN, the first offset and the reception time of the LTM cell switching command. The first reference SFN, the first offset and the reception time of the LTM cell switching command Figure 7 The first reference SFN and the first offset are similar and will not be described again here.

[0333] In some embodiments, when the communication device 800 is used to implement Figure 6 or Figure 7 In the method embodiment shown, the function of the terminal device is: the transceiver unit 810 is also used to send a measurement report to the source DU. Figure 6 , Figure 7 The measurement report is similar to that in , and will not be repeated here.

[0334] For more detailed description of the transceiver unit 810 and the processing unit 820, refer to Figure 6 or Figure 7 Related description in the method embodiment shown.

[0335] like Fig.10 As shown, the communication device 900 includes a processor 910 and an interface circuit 920. The processor 910 and the interface circuit 920 are coupled to each other. It is understood that the interface circuit 920 is a transceiver or an input-output interface. Optionally, the communication device 900 also includes a memory 930 for storing instructions executed by the processor 910 or storing input data required by the processor 910 to execute instructions or storing data generated after the processor 910 executes instructions.

[0336] When the communication device 900 is used to implement Figure 5 , Figure 6 or Figure 7 When the method is performed, the processor 910 is used to implement the functions of the processing unit 820, and the interface circuit 920 is used to implement the functions of the receiving unit 710, the sending unit 720 or the transceiver unit 810.

[0337] When the above communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiment. The terminal chip receives information from other modules in the terminal (such as a radio frequency module or an antenna), and the information is sent by the base station to the terminal; or the terminal chip sends information to other modules in the terminal (such as a radio frequency module or an antenna), and the information is sent by the terminal to the base station.

[0338] When the above-mentioned communication device is a module applied to a base station (or a network device), the base station module implements the function of the base station in the above-mentioned method embodiment. The base station module receives information from other modules in the base station (such as a radio frequency module or an antenna), and the information is sent by the terminal to the base station; or, the base station module sends information to other modules in the base station (such as a radio frequency module or an antenna), and the information is sent by the base station to the terminal. The base station module here can be a baseband chip of a base station, or it can be a DU or other module. The DU here can be a DU under an open radio access network (O-RAN) architecture.

[0339] It is understandable that the processor in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0340] The method steps in the embodiments of the present application can be implemented in hardware or in software instructions that can be executed by a processor. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, mobile hard disks, compact disc read-only memory (CD-ROM) or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a base station or a terminal. The processor and the storage medium can also be present in a base station or a terminal as discrete components.

[0341] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instruction is loaded and executed on a computer, the process or function described in the embodiment of the present application is executed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device or other programmable device. The computer program or instruction may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer program or instruction may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server, data center, etc. that integrates one or more available media. The available medium may be a magnetic medium, for example, a floppy disk, a hard disk, a tape; it may also be an optical medium, for example, a digital video disc; it may also be a semiconductor medium, for example, a solid-state hard disk. The computer-readable storage medium may be a volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

[0342] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0343] In the present application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of the present application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship; in the formula of the present application, the character " / " indicates that the previous and next associated objects are in a "division" relationship. "Including at least one of A, B and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B and C.

[0344] It is understood that the various numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that: The method is applicable to a target distribution unit DU, and the method is applied to a mobility LTM switching scenario triggered by layer 1 / layer 2. The method includes: receiving a first request message from a centralized unit CU, where the first request message is used to request the target DU to provide a first configuration, where the first configuration includes a period P, where P cannot be divided by N, where N is a period of a radio frame, and where P and N are positive integers greater than or equal to 1; A first response message is sent to the CU, where the first response message includes the first configuration, where the first configuration is used to determine a first target time domain position, and the first target time domain position is used to communicate with a terminal device.

2. The method according to claim 1, characterized in that The first configuration also includes a first reference system frame number SFN and a first offset, and the period P, the first reference SFN and the first offset are used to determine the first target time domain position.

3. The method according to claim 2, characterized in that Before sending the first response message to the CU, the method further includes: The first reference SFN is determined according to the first time period, the first reference SFN does not belong to the SFN within the first time period, the start time of the first time period is the time when the first request message is received, and the duration of the first time period is less than or equal to N / 2.

4. The method according to claim 2, characterized in that: Before sending the first response message to the CU, the method further includes: receiving time period information from the CU, where the time period information is used to indicate a first time period, where the first time period includes an expected sending time period of the first configuration or an expected receiving time period of the first configuration; The first reference SFN is determined according to the first time period, where the first reference SFN does not belong to the SFN in the first time period.

5. The method according to any one of claims 2 to 4, characterized in that The first candidate value set includes the first reference SFN and the second reference SFN, the first reference SFN and the second reference SFN are before a first time, the first reference SFN is closer to the first time than the second reference SFN, the first time is the time when the first request message is received, or the first time is within the expected sending time period of the first response message.

6. The method according to claim 1, characterized in that The method further comprises: Receive a first count value from the CU, where the first count value is used to determine the number K1 of radio frame periods, where the number K1 starts counting from a time corresponding to a third reference SFN, where the third reference SFN is used by the source DU to determine a second target time domain position, and K1 is an integer greater than or equal to 0; Determine a first reference SFN and a first offset according to the first count value, wherein the period P, the first reference SFN and the first offset are used to determine the first target time domain position, and the first target time domain position is the same as the second target time domain position; The first reference SFN and the first offset are sent to the CU.

7. The method according to claim 6, characterized in that The determining, according to the first count value, a first reference SFN and a first offset includes: receiving synchronization information from the CU, where the synchronization information is used for frame synchronization and subframe synchronization between the source DU and the target DU; The first reference SFN and / or the first offset are determined according to the synchronization information and the first count value.

8. The method according to any one of claims 1 to 7, characterized in that The method further comprises: After the terminal device switches from the source DU to the target DU, a first target SFN and a first target subframe number are determined, where the first target SFN and the first target subframe number are the first target time domain position.

9. The method according to claim 8, characterized in that The first target SFN and the first target subframe number satisfy the following formula: (the second count value×N+the first target SFN×M+the first target subframe number) modulo the period P=(the first reference SFN×M+the first bias) modulo the period P, wherein modulo is a modular operation, M is the duration of a wireless frame, the second count value is used to determine the number K2 of wireless frame periods, the number K2 is counted from the time corresponding to the first reference SFN, the period P, the first reference SFN and the first bias are used to determine the first target time domain position, and K2 is an integer greater than or equal to 0.

10. A communication method, characterized in that: The method is applicable to a source distribution unit DU, and the method is applied to a mobility LTM switching scenario triggered by layer 1 / layer 2. The method includes: Sending auxiliary information to the target DU through a centralized unit CU, wherein the auxiliary information is used by the target DU to determine a first target time domain position, and the first target time domain position is used to communicate with a terminal device; Receiving an RRC reconfiguration message from the CU, where the RRC reconfiguration message includes a period P, where the period P is used by the terminal device to determine the first target time domain position, P cannot be divided by N, N is the period of the radio frame, and P and N are positive integers greater than or equal to 1; Send the RRC reconfiguration message to the terminal device.

11. The method according to claim 10, characterized in that The RRC reconfiguration message also includes a first reference system frame number SFN and a first offset, and the period P, the first reference SFN and the first offset are used by the terminal device to determine the first target time domain position.

12. The method according to claim 11, characterized in that The auxiliary information includes time period information, and the time period information includes a first time period, and the first time period includes an expected sending time period for sending a first configuration to the terminal device or an expected receiving time period for the terminal device to receive the first configuration, and the first configuration includes the period P, the first reference SFN and the first bias.

13. The method according to claim 12, characterized in that The sending the RRC reconfiguration message to the terminal device includes: Within the first time period, the RRC reconfiguration message is sent to the terminal device.

14. The method according to any one of claims 10 to 13, characterized in that The method further comprises: receiving a measurement report from the terminal device, wherein the measurement report includes a measurement result of a target cell; An LTM cell switching command is sent to the terminal device, wherein the LTM cell switching command instructs the terminal device to switch to the target cell, and the target cell belongs to the target DU.

15. The method according to claim 10, characterized in that The method further comprises: Sending a first count value to the target DU through the CU, where the first count value is used to determine the number K1 of radio frame cycles, where the number K1 starts counting from a time corresponding to a third reference SFN, where the third reference SFN is used by the source DU to determine a second target time domain position, and K1 is an integer greater than or equal to 0; Receiving, through the CU, a first reference SFN and a first offset from the target DU, wherein the period P, the first reference SFN, and the first offset are used to determine the first target time domain position, and the first target time domain position is the same as the second target time domain position; Sending the first reference SFN and the first offset to the terminal device.

16. The method according to claim 10 or 15, characterized in that The auxiliary information includes synchronization information, and the synchronization information is used for the source DU and the target DU to perform frame synchronization and subframe synchronization.

17. The method according to claim 15, characterized in that The sending the first reference SFN and the first offset to the terminal device includes: receiving a measurement report from the terminal device, wherein the measurement report includes a measurement result of a target cell; An LTM cell switching command is sent to the terminal device, wherein the LTM cell switching command includes the first reference SFN and the first offset, and the LTM cell switching command instructs the terminal device to switch to the target cell, and the target cell belongs to the target DU.

18. A communication method, characterized in that: The method is applicable to a terminal device, and the method is applied to a mobility LTM switching scenario triggered by layer 1 / layer 2. The method includes: Receiving an RRC reconfiguration message from a source distribution unit DU, wherein the RRC reconfiguration message includes a configuration of a target cell, wherein the configuration of the target cell includes a period P, wherein the target cell belongs to a target DU, P cannot be divided by N, N is a period of a radio frame, and P and N are positive integers greater than or equal to 1; Receiving an LTM cell switching command from the source DU, the LTM cell switching command instructing the terminal device to switch to the target cell; A first target time domain position is determined according to the configuration of the target cell, where the first target time domain position is used to communicate with the target DU.

19. The method according to claim 18, characterized in that The configuration of the target cell also includes a first reference system frame number SFN and a first offset, and the period P, the first reference SFN and the first offset are used to determine the first target time domain position.

20. The method according to claim 19, characterized in that The determining, according to the configuration of the target cell, a first target time domain position includes: The first target time domain position is determined according to the configuration of the target cell and the reception time of the RRC reconfiguration message.

21. The method according to claim 18, characterized in that The LTM cell switching command also includes a first reference system frame number SFN and a first offset, and the period P, the first reference SFN and the first offset are used to determine the first target time domain position.

22. The method according to claim 21, characterized in that The determining, according to the configuration of the target cell, a first target time domain position includes: The first target time domain position is determined according to the configuration of the target cell, the first reference system frame number SFN, the first offset and the reception time of the LTM cell switching command.

23. The method according to any one of claims 19 to 22, characterized in that The first time domain position includes a first target SFN and a first target subframe number, and the first target SFN and the first target subframe number satisfy the following formula: (the third count value×N+the first target SFN×M+the first target subframe number) modulo the period P=(the first reference SFN×M+the first offset) modulo the period P, wherein modulo is a modular operation, M is the duration of a wireless frame, and the third count value is used to determine the number K3 of wireless frame periods, and the number K3 is counted from the time corresponding to the first reference SFN, and K3 is an integer greater than or equal to 0.

24. The method according to any one of claims 18 to 23, characterized in that The method further comprises: Send a measurement report to the source DU, where the measurement report includes a measurement result of the target cell.

25. A communication device, characterized in that: Comprising means for performing the method as claimed in any one of claims 1 to 24.

26. A communication device, characterized in that: The communication device comprises: at least one processor and a communication interface, wherein the communication interface is used for the communication device to exchange information with other communication devices, and when program instructions are executed in the at least one processor, the communication device executes the method as claimed in any one of claims 1 to 9.

27. A communication device, characterized in that: The communication device comprises: at least one processor and a communication interface, wherein the communication interface is used for the communication device to exchange information with other communication devices, and when the program instructions are executed in the at least one processor, the communication device executes the method as described in any one of claims 10 to 17.

28. A communication device, characterized in that: The communication device comprises: at least one processor and a communication interface, wherein the communication interface is used for the communication device to exchange information with other communication devices, and when the program instructions are executed in the at least one processor, the communication device executes the method as described in any one of claims 18 to 24.

29. A communication system comprising the communication device according to claim 26, the communication device according to claim 27 and the communication device according to claim 28.

30. A computer program product, characterized in that The method comprises program instructions, and when the program instructions are executed, the method according to any one of claims 1 to 24 is performed.

31. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program code for execution by a device, and when the program code is executed, the method according to any one of claims 1 to 24 is performed.

32. A chip, characterized in that: The chip includes at least one processor, and when program instructions are executed by the at least one processor, the method according to any one of claims 1 to 24 is executed.

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