Communication method and related device

Abstract

Provided in the present application are a communication method and a related device. The communication method is applicable to a target DU, and is applied to an LTM switching scenario. The method comprises: receiving a first request message from a CU, wherein the first request message is used for requesting a target DU to provide a 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 cycle P, P cannot be divided by N, N is a cycle of a radio frame, P and N are positive integers greater than or equal to 1, and the first configuration is used for determining a first target time-domain position, which is used for communicating with a terminal device. In the method, a target DU sends to a CU a cycle P which cannot be divided by a cycle N of a radio frame, such that a terminal device receives the cycle 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 the transmission of data of a service within a specific cycle.

Description

A communication method and related equipment

[0001] This application claims priority to the Chinese patent application with application number 202311294412.6 filed with the State Intellectual Property Office of China on September 28, 2023, and priority to the Chinese patent application with the invention name “A communication method and related equipment”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and more particularly, to a communication method, a communication device, a communication system, a computer program product, a computer-readable storage medium, and a chip. Background Art

[0003] In fifth-generation mobile communication technology (5G), the movement of terminal devices triggers handovers. The basic goal of handovers is to switch the terminal device to a neighboring cell with better signal quality before the signal quality of the terminal device's serving cell becomes unavailable, thereby providing continuous, uninterrupted communication services and effectively preventing call drops caused by deteriorating serving cell signal quality. In the 5G radio access network (RAN) architecture, a base station consists of a distributed unit (DU) and a central unit (CU). The DU is responsible for handling physical layer functions and real-time Layer 2 functions, such as radio link control (RLC), medium access control (MAC), and physical layer (PHY) layer functions. The CU is responsible for handling non-real-time wireless higher-layer protocol stack functions, such as service data adaptation protocol (SDAP), radio resource control (RRC), and packet data convergence protocol (PDCP). The CU and DU communicate over the F1 interface, with a maximum transmission latency of approximately 3ms to 10ms. In layer 1 / layer 2 triggered mobility (LTM) handovers, the DU determines whether to initiate a handover based on the terminal device's measurement results, sending the handover command directly to the terminal device. This reduces interaction between the CU and DU and reduces handover latency. However, in LTM handover scenarios, there are issues with transmitting data for specific periodic services after the terminal device switches from the source DU to the target DU.

[0004] Therefore, how to support data transmission of services with a specific cycle in the LTM switching scenario becomes an urgent problem to be solved.

[0005] Summary of the Invention

[0006] 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.

[0007] In a first aspect, a communication method is provided. The method is executed by a target DU and 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; and sending a first response message to the CU, the first response message including the first configuration. The first configuration includes a period P, where P cannot be divided by N, where N is the period of a 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, which is used to communicate with a terminal device.

[0008] 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 for services of a specific period.

[0009] In combination with the first aspect, in some implementations of the first aspect, the first configuration further 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.

[0010] 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.

[0011] In conjunction with the first aspect, in certain implementations of the first aspect, before sending the first response message to the CU, a first reference SFN is determined based on the first time period. The first reference SFN does not belong to an SFN within the first time period. The first time period starts at 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.

[0012] 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.

[0013] 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, 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; based on the first time period, a first reference SFN is determined, and the first reference SFN does not belong to an SFN within the first time period.

[0014] In an embodiment of the present application, the target DU receives time period information from the CU, thereby determining the first reference SFN based on the expected sending time period or expected receiving time period of the first configuration, thereby avoiding errors in the terminal device when counting based on the first reference SFN.

[0015] 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.

[0016] 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.

[0017] In combination with the first aspect, in certain implementations of the first aspect, a first count value is received from the CU, where the first count value is used to determine the number K1 of wireless frame periods, where the number K1 is counted from the time corresponding to the third reference SFN, where 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; based on the first count value, a first reference SFN and a first offset are determined, where the period P, the first reference SFN, and the first offset are used to determine the first target time domain position, where the first target time domain position is the same as the second target time domain position; and the first reference SFN and the first offset are sent to the CU.

[0018] In an embodiment of the present application, the target DU determines the first reference SFN and the first offset based on the 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, and then aligns the configuration of the target DU and the terminal device.

[0019] 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; based on the synchronization information and the first count value, a first reference SFN and / or the first bias is determined.

[0020] 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 current radio frame period 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.

[0021] 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, where the first target SFN and the first target subframe number are the first target time domain position.

[0022] 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.

[0023] In conjunction with the first aspect, in certain implementations of the first aspect, the first target SFN and the first target subframe number satisfy the following formula:

[0024] (Second count value × N + first target SFN × M + first target subframe number) modulo period P = (first reference SFN × M + first offset) modulo period P. Modulo represents a modular operation, and M represents the duration of a radio frame. The second count value is used to determine the number K2 of radio frame periods, which is counted starting 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, where K2 is an integer greater than or equal to 0.

[0025] 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, thereby supporting the transmission of data of a service of a specific period through the time domain position.

[0026] In the second aspect, a communication method is provided. The method is executed by the source DU and 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.

[0027] 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.

[0028] In combination with the second aspect, in some 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.

[0029] 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.

[0030] In conjunction with the second aspect, in certain implementations of the second aspect, the auxiliary information includes time period information, where the time period information includes a first time period, where the first time period includes an expected time period for sending a first configuration to a terminal device or an expected time period for receiving the first configuration by the terminal device. The first configuration includes a period P, a first reference SFN, and a first offset.

[0031] In an embodiment of the present application, the source DU sends the 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.

[0032] 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.

[0033] 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 the measurement results of the 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 the target cell, which belongs to the target DU.

[0034] 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.

[0035] 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 is counted 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.

[0036] In an embodiment of the present application, the source DU sends a first count value to the CU, so that the target DU determines the first reference SFN and the first offset based on the first count value, so that the terminal device receives the first reference SFN and the first offset, and then determines the first target time domain position.

[0037] In combination with the second aspect, in some implementations of the second aspect, the auxiliary information includes synchronization information, where the synchronization information is used for frame synchronization and subframe synchronization between the source DU and the target DU.

[0038] 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.

[0039] In conjunction with the second aspect, in certain implementations of the second aspect, a measurement report is received from a terminal device, the measurement report including measurement results of a target cell; and an LTM cell handover command is sent to the terminal device. The LTM cell handover command includes a first reference SFN and a first offset. The LTM cell handover command instructs the terminal device to handover to a target cell, where the target cell belongs to a target DU.

[0040] 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.

[0041] In a 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 including the configuration of the target cell, the configuration of the target cell including a period P, the target cell belongs to a target DU, 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; 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; 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.

[0042] 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.

[0043] In combination with the second aspect, in certain implementations of the second aspect, the configuration of the target cell further 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.

[0044] In an embodiment of the present application, the terminal device receives the first reference SFN and the first offset, 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 offset, thereby supporting the transmission of data of services of a specific period.

[0045] In combination with the second aspect, in certain implementations of the second aspect, the first target time domain position is determined based on the configuration of the target cell and the reception time of the RRC reconfiguration message.

[0046] 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.

[0047] 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.

[0048] In an embodiment of the present application, the terminal device receives the first reference SFN and the first offset, 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 offset, thereby supporting the transmission of data of services of a specific period.

[0049] 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.

[0050] 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.

[0051] In conjunction with the second aspect, in certain implementations of the second aspect, the first target 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:

[0052] (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 represents a modular operation and M represents the duration of a radio frame. The third count value is used to determine the number K3 of radio frame periods. This number K3 is counted starting from the time corresponding to the first reference SFN, and K3 is an integer greater than or equal to 0.

[0053] In an embodiment of the present application, the terminal device determines the 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.

[0054] 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.

[0055] 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.

[0056] In a fourth aspect, a communication device is provided, which includes a module for executing the method as described in any one of the first to third aspects and any possible implementation manners of the first to third aspects.

[0057] In a fifth aspect, a communication device is provided. The communication device includes: 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 performs the method described in the first aspect or any possible implementation of the first aspect.

[0058] In a sixth aspect, a communication device is provided. The communication device includes: 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 performs the method described in the second aspect or any possible implementation of the second aspect.

[0059] In a seventh aspect, a communication device is provided. The communication device includes: 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 performs the method described in the third aspect or any possible implementation of the third aspect.

[0060] 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.

[0061] In a ninth aspect, a computer program product is provided, wherein the computer program product includes program instructions, and when the program instructions are executed, the method described in any one of the first to third aspects and any possible implementation of the first to third aspects is executed.

[0062] In a tenth aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores program code for execution by a device, and when the program code is executed, the method described in any of the first to third aspects and any possible implementation of the first to third aspects is executed.

[0063] In an eleventh aspect, a chip is provided. The chip includes at least one processor, and when program instructions are executed by the at least one processor, the method described in any one of the first to third aspects and any possible implementation of the first to third aspects is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG1 is a schematic architecture diagram of a 5G system.

[0065] FIG2 is a schematic architecture diagram of a communication system according to an embodiment of the present application.

[0066] FIG3 is a schematic diagram of a radio frame period according to an embodiment of the present application.

[0067] FIG4 is a schematic flow chart of LTM switching.

[0068] FIG5 is a schematic flowchart of a communication method according to an embodiment of the present application.

[0069] FIG6 is a schematic flowchart of a communication method according to another embodiment of the present application.

[0070] FIG7 is a schematic flowchart of a communication method according to another embodiment of the present application.

[0071] FIG8 is a schematic structural diagram of a communication device according to an embodiment of the present application.

[0072] FIG9 is a schematic structural diagram of a communication device according to another embodiment of the present application.

[0073] FIG10 is a schematic structural diagram of a communication device according to another embodiment of the present application. DETAILED DESCRIPTION

[0074] The technical solution in this application will be described below with reference to the accompanying drawings.

[0075] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: 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), world-wide interoperability for microwave access (WiMAX) communication system, fourth generation (4G) system, fifth generation (5G) system or new radio (NR), etc.

[0076] A terminal device is a device with wireless transceiver capabilities that can send signals to a network device or receive signals from a network device. A terminal may 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. A user device may 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 capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle 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 thereto.

[0077] The network device in the embodiments of the present application may be a device for communicating with a terminal, and for connecting the terminal to a radio access network (RAN). A network device may also sometimes be referred to as an access network device, an access network node, or a base station. It is understood that in systems employing different radio access technologies, the name of the device having base station functionality may vary. For ease of description, in the embodiments of the present application, the device providing wireless communication access functionality for a terminal is collectively referred to as a network device. The network equipment can be a base transceiver station (BTS) in the global system for mobile communications (GSM) system or code division multiple access (CDMA), a base station (NodeB, NB) in the wideband code division multiple access (WCDMA) system, an evolved NodeB (eNB or eNodeB) in the LTE system, a base station (gNodeB, gNB) in NR, a next generation evolved base station (ng-eNB) or a transmission receiving point / transmission reception point (TRP), a base station subsequently evolved by the 3rd Generation Partnership Project (3GPP), an access node, a wireless relay node, a wireless backhaul node in the wireless network communication technology (WiFi) system, or a cloud radio access network (CRN). The network device may be a wireless controller in a 5G network (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 (gNB) or a transmission point, such as a baseband unit (BBU), a distributed unit (DU), a centralized unit (CU), etc., and the embodiments of the present application are not limited.

[0078] 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 memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through processes, 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 browsers, address books, word processing software, and 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 is possible to 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 network device, or a functional module in the terminal or network device that can call and execute a program, such as a chip or processor.

[0079] In addition, various aspects or features of the present application can be implemented as methods, apparatus, or articles of manufacture using standard programming and / or engineering techniques. For example, computer-readable media can include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes), 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 can represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" can include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data.

[0080] To facilitate understanding of the embodiments of the present application, several terms involved in the present application are first briefly explained.

[0081] 1. Wireless frame

[0082] In mobile communications, data is transmitted on wireless networks in radio frames. That is, a radio frame is the time unit for data transmission. A radio frame can include at least one subframe, each subframe can include at least one slot, and each slot can include at least one symbol. When the sub-carrier spacing (SCS) is 30 kilohertz (kHz), a radio frame can include 10 subframes, each subframe can include 2 slots, and each slot can include 14 symbols. When the duration of a radio frame is 10 milliseconds (ms), each subframe has a duration of 1 ms, and each slot has a duration of 0.5 ms. This allows multiple users to be assigned different subframes for data transmission within a second (s). The system frame number (SFN) of a radio frame can range from 0 to 1023. When the SFN of a radio frame is 1023, the SFN of the next radio frame can be 0, thus implementing a cyclic value.

[0083] 2. Switch

[0084] In the 5G system, a terminal device can trigger a handover due to mobility while in the RRC connected state. The basic goal of handover is to switch the terminal device to a neighboring cell with better signal quality before the signal quality of the serving cell becomes unavailable for communication, thereby providing continuous and uninterrupted communication services and effectively preventing call drops caused by deteriorating signal quality in the serving cell. Layer 3 (L3) handover means that the CU can receive measurement reports from the DU and determine whether to initiate a handover based on the measurement reports. The measurement reports are 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, which then sends the handover command to the terminal device, thereby implementing the handover. Because data is transmitted between the CU and DU via 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 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.

[0085] 3. Discontinuous reception (DRX)

[0086] DRX can be used to save energy in 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. A 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 acknowledgement (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.

[0087] 4. Configured grant (CG)

[0088] CG is used for ultra-reliable and low latency communications (URLLC). Terminal devices can send data directly without having to wait for PDCCH scheduling for uplink transmission, thus reducing transmission latency. Similar to DRX, CG also requires adapting to service cycles to avoid affecting service data transmission.

[0089] Figure 1 is a schematic architecture diagram of a 5G system. The 5G system 100 in Figure 1 includes a 5G core network (5G core, 5GC) and a 5G radio access network (NG RAN). The 5G core network can include at least one access and mobility management function (AMF) network element / user plane function (UPF) network element. The NG RAN includes at least one gNB and / or at least one ng-eNB.

[0090] 5GC can be used to implement functions such as registration, connection, and session management. 5GC can also include authentication server function (AUSF) network elements, network exposure function (NEF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, unified data repository (UDR) network elements, network repository function (NRF) network elements, application function (AF) network elements, and session management function module (SMF) network elements.

[0091] The AMF network element primarily performs functions such as mobility management and access authentication / authorization, and can also communicate user policies between terminal devices and the PCF network element. The UPF network element serves as the interface (UPF) with the data network, implementing user plane data forwarding, session / flow-level billing and statistics, and bandwidth limiting. The AUSF network element authenticates users to determine whether they are allowed to access the network. The NEF network element exposes the services and capabilities of 3GPP network functions to the AF network element, while also enabling the AF to provide information to 3GPP network functions. The PCF network element manages policy for billing and quality of service (QoS) policies. The UDM network element manages functions such as subscription data and user access authorization. The UDR network element manages the storage and access of subscription data, policy data, application data, and other types of data. The NRF network element provides network element discovery, providing network element information corresponding to the network element type upon request from other network elements. The NRF network element also provides network element management services, such as network element registration, update, and deregistration, as well as network element status subscription and push notification. The AF network element can be used to convey the requirements of the application side to the network side. The SMF network element can implement session management functions such as the allocation of Internet Protocol (IP) addresses for terminal devices, UPF network element selection, billing and QoS policy control.

[0092] Each gNB can provide the termination point for the NR user plane and control plane protocols. Each ng-eNB can provide the termination point for 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 via the Xn interface. Each gNB is connected to the 5GC via the NG interface. Specifically, each gNB is connected to the AMF via the NG-C interface, and each gNB is connected to the UPF via the NR-U interface. Similarly, each ng-eNB is connected to the 5GC via the NG interface. Specifically, each ng-eNB is connected to the AMF via the NG-C interface, and each ng-eNB is connected to the UPF via the NR-U interface.

[0093] FIG2 is a schematic structural block diagram of a communication system provided in an embodiment of the present application. The communication system 200 in FIG2 includes a source DU 201, a terminal device 202, a target DU 203, and a CU 204.

[0094] Source DU 201 and target DU 203 are responsible for processing physical layer functions and real-time Layer 2 (L2) functions, such as RLC, MAC, and PHY layer functions. CU 204 is responsible for processing non-real-time wireless upper layer protocol stack functions, such as SDAP, RRC, PDCP, and other functions. At least two of source DU 201, target DU 203, and CU 204 may belong to the same network device or different network devices, but this embodiment of the present application is not limited to this. That is, source DU 201 and target DU 203 may belong to the same network device or different network devices. Source DU 201 and CU 204 may belong to the same network device or different network devices. Target DU 203 and CU 204 may belong to the same network device or different network devices. This network device is the gNB or ng-eNB in ​​Figure 1.

[0095] Source DU 201 and target DU 203 communicate through CU 204. When source DU 201, target DU 203, and CU 204 belong to the same network device, source DU 201 sends data to CU 204 via the F1 interface, and CU 204 sends data to target DU 203 via the F1 interface. When source DU 201 and target DU 203 belong to different network devices, source DU 201 sends data to the CU of the network device where source DU 201 is located, which in turn sends data to the CU of the network device where target DU 203 is located, which in turn sends data to the CU of the network device where target DU 203 is located, thereby achieving communication between source DU 201 and target DU 203. The CU 204 is the CU of the network device where source DU 201 is located, or the CU 204 is the CU of the network device where target DU 203 is located.

[0096] Terminal device 202 is connected to source DU 201. That is, terminal device 202 accesses the source cell, which belongs to source DU 201. After receiving the handover command, terminal device 202 also accesses the target cell. The target cell belongs to target DU 203. That is, terminal device 202 is connected to target DU 203. The handover command is an LTM cell handover command, which includes identification information of the target cell.

[0097] 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 shown in FIG. 3 .

[0098] Figure 3 is a schematic diagram of a radio frame period provided in an embodiment of the present application. As shown in Figure 3, the radio frame periods of source DU 201 and target DU 203 are the same. For example, a radio frame period includes 1024 radio frames, and the SFNs of these 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 source DU 201 and target DU 203 may be the same or different. For example, at the same time, the SFN corresponding to source DU 201 is 2, and the SFN corresponding to target DU 203 is 0.

[0099] When the service cycle is evenly 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 evenly 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.

[0100] For example, if the service period is 10240ms, the service data can be transmitted in each radio frame period using a radio frame with SFN 0. If the service period is 10230ms, the service data can be transmitted in the first radio frame period using radio frames with SFN 0 and SFN 1023, but in the second radio frame period using radio frames with SFN 1022.

[0101] When the service period cannot be divided evenly by the wireless frame period, since the SFN corresponding to the service is different in different wireless frame periods, 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 the service of a specific period after the terminal device switches to the target DU.

[0102] Figure 4 is a schematic flow chart of LTM switching, which includes the following steps.

[0103] S301: The terminal device sends a measurement report to the source DU. The measurement report includes layer 3 (L3) measurement results, specifically, measurement results of neighboring cells. Neighboring cells refer to cells to which the terminal device may switch after moving.

[0104] 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.

[0105] S303: The CU decides to initiate LTM configuration based on the measurement report. The CU decides to initiate LTM configuration based on the measurement results of the neighboring cells included in the measurement report.

[0106] S304: The CU sends a UE context establishment request message to the candidate DU. The UE context establishment request message may include the identity (ID) of the first candidate cell. It is understood that the CU also indicates the ID of the source DU. The source DU ID is used to request the candidate DU to provide physical random access channel (PRACH) resources for the source DU.

[0107] S305: The candidate DU sends a UE context establishment response message to the CU. When the candidate DU accepts the LTM configuration request, 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, the random access channel (RACH) configuration, and the reference signal (RS) configuration.

[0108] 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.

[0109] 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, where the CSI resource configuration is used to send a lower layer measurement result of the first candidate cell in the source cell.

[0110] 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 cells include the source cell.

[0111] 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.

[0112] 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).

[0113] S311, the source DU sends an RRC reconfiguration message to the terminal device.

[0114] S312, the terminal device sends an RRC reconfiguration completion message to the source DU.

[0115] S313: The source DU sends an RRC reconfiguration complete message to the CU. The source DU sends the RRC reconfiguration complete message to the CU via a UL RRC message.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] Among them, S314, S315, and S316 are optional steps and may not be executed.

[0120] S317: The terminal device sends a measurement report to the source DU. The measurement report includes lower layer measurement results. The terminal device measures the RS according to the RS configuration, and then sends the measurement results to the source DU according to the CSI resource configuration.

[0121] S318: The source DU decides to perform LTM handover on the candidate cell based on the measurement report.

[0122] S319: The source DU sends an LTM cell handover command to the terminal device. The LTM cell handover command includes the identifier of the target cell, and the LTM cell handover command is used to indicate the first candidate cell as the target cell for handover. The LTM cell handover command may also include beam information of the target cell (e.g., TCI state identifier) ​​and timing advance information of the target cell. The beam information is used by the terminal device to receive downlink control information in a random access-free manner.

[0123] S320: The source DU sends an LTM cell change notification message to the CU. The LTM cell change notification message indicates that an LTM cell handover command has been initiated for the terminal device. The LTM cell change notification message may include the target cell ID and beam information. It is understood that the target cell is one of the candidate cells in the aforementioned steps.

[0124] 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.

[0125] S322: The target DU detects terminal access. For example, the terminal device accesses the target DU via random access or random access-free access. If the random access-free access is used, the target DU sends downlink control information to the terminal device based on the beam information. In the random access-free access mode, the terminal device accesses the target cell via PUSCH based on the timing advance information in the LTM cell handover command, rather than via PRACH.

[0126] 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.

[0127] 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.

[0128] S325: The source DU sends a UE context release completion message to the CU.

[0129] In the LTM switching scenario, if the service period cannot be divided evenly by the radio frame period, then after the terminal device accesses the target cell, the target DU cannot determine the time domain position corresponding to the service, resulting in problems in transmitting data of services with a specific period after the terminal device switches to the target DU.

[0130] Figure 5 is a schematic flow chart of a communication method provided by an embodiment of the present application. The communication method 400 in Figure 5 is executed by the communication system in Figure 1 or Figure 2. Figure 5 includes the following steps.

[0131] S401: The CU sends a first request message to a candidate DU.

[0132] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, where the period P is not divisible by N. N is the radio frame period, 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 communication between the candidate DU and the terminal device.

[0133] 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) configuration, the first target time domain position is used to measure neighboring cells at the GAP.

[0134] In some embodiments, the period of the radio frame is the product of a first value and the duration of a radio frame, and the first value is the maximum value of SFN plus 1.

[0135] For example, assuming 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.

[0136] In some embodiments, the first request message is a UE context setup request message.

[0137] In some embodiments, the first request message further includes auxiliary information. The auxiliary information is used by the candidate DU to determine the first target time domain position.

[0138] 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, which includes an expected transmission time period of a first configuration or an expected reception time period of the 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 radio frame synchronization information and / or subframe synchronization information.

[0139] For example, the synchronization information may include a first UTC time and the SFN and subframe number of the source DU corresponding to the first UTC time. The candidate DU may determine the SFN and subframe number of the candidate DU corresponding to the first UTC time based on 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.

[0140] S402: The candidate DU sends a first response message to the CU, where the first response message includes the first configuration.

[0141] In some embodiments, the first response message is a UE context setup response message.

[0142] 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 message includes the RRC reconfiguration message. The RRC reconfiguration message includes the first configuration.

[0143] 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.

[0144] 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 86.

[0145] When the first request message includes time period information, the candidate DU may determine a first reference SFN based on the first time period included in the time period information. The first reference SFN does not belong to the SFN within the first time period. For specific implementation, see the description in step S504.

[0146] 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 based on the synchronization information, thereby determining the first reference SFN based on the first count value received subsequently. The first count value is used to determine the number K1 of wireless frame periods, 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.

[0147] In some embodiments, the candidate DU receives a first count value from the CU after sending the first response message.

[0148] 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 with the data matching the service of the specific period.

[0149] Figure 6 is a schematic flow chart of a communication method provided in an embodiment of the present application. The communication method 500 in Figure 6 is executed by the communication system in Figure 1 or Figure 2. Figure 6 includes the following steps.

[0150] S501: The CU sends a second request message to the source DU. Correspondingly, the source DU receives the second request message from the CU.

[0151] 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 for the candidate DU to communicate with the terminal device.

[0152] 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.

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

[0154] 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.

[0155] In some embodiments, the second response message is a UE context modification response message.

[0156] 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.

[0157] S503: The CU sends a first request message to the candidate DU. Correspondingly, the candidate DU receives the first request message from the CU.

[0158] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, where the period P is not divisible by N. N is the radio frame period, 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 communication between the candidate DU and the terminal device.

[0159] 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 at the GAP.

[0160] In some embodiments, the period of the radio frame is the product of a first value and the duration of a radio frame, and the first value is the maximum value of SFN plus 1.

[0161] 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 that of step S401 and will not be repeated here.

[0162] In some embodiments, the first request message is a UE context setup request message.

[0163] S504: The candidate DU sends a first configuration to the CU. Correspondingly, the CU receives the first configuration from the candidate DU.

[0164] 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. Step S504 is implemented similarly to step S402.

[0165] In some embodiments, the first configuration is carried in a first response message. The first response message is a UE context setup response message.

[0166] After the candidate DU receives the first request message, the candidate DU determines a first time period based on the time period information in the first request message. The candidate DU also determines a first reference SFN based on the first time period. The first reference SFN does not belong to an SFN within the first time period.

[0167] 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.

[0168] When the first request message does not include time period information, the candidate DU independently determines a 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. The first reference SFN does not belong to an SFN within the first time period.

[0169] 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 an expected transmission time period for the candidate DU to send a first response message, or the first time is within a first time period. The time period includes at least one time slot. The candidate DU sends the first response message within the expected transmission time period.

[0170] For example, assuming that the first candidate value set includes 0 and 512, if the SFN corresponding to the first time is 600, since both 0 and 512 are before 600 and 512 is closer to 600 than 0, the candidate DU determines the first reference SFN as 512.

[0171] When the first request message does not include time period information, the candidate DU determines the first reference SFN based on a 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 time period for the candidate DU to send a first response message. During the expected time period, the candidate DU sends the first response message to the CU.

[0172] Optionally, the candidate DU may determine the SFN corresponding to the source DU based on the first reference SFN and the first offset, and the SFN is used for communication between the source DU and the terminal device. In other words, the candidate DU may determine the first offset based on the first reference SFN and the SFN.

[0173] 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. If the first reference SFN is 512, the first offset is 598-512=86.

[0174] Optionally, before step S504, the candidate DU receives synchronization information from the CU. This synchronization information is used for frame and subframe synchronization between the source DU and the candidate DU. This synchronization information includes radio frame synchronization information and / or subframe synchronization information. After receiving this 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.

[0175] For example, the synchronization information may include a first UTC time and the SFN and subframe number of the source DU corresponding to the first UTC time. The candidate DU may determine the SFN and subframe number of the candidate DU corresponding to the first UTC time based on 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.

[0176] S505: The CU sends a first configuration to the source DU. Correspondingly, the source DU receives the first configuration, which includes a period P, a first reference SFN, and a first offset.

[0177] 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.

[0178] 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.

[0179] 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 and includes a period P.

[0180] 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.

[0181] 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.

[0182] In some embodiments, the configuration of the candidate cell further includes a first reference SFN and a first offset.

[0183] In some embodiments, the source DU receives a 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.

[0184] S507: The terminal device sends a configuration completion message to the source DU. Correspondingly, the source DU receives the configuration completion message.

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

[0186] S508: The source DU sends a configuration completion message to the CU. Correspondingly, the CU receives the configuration completion message from the source DU.

[0187] In some embodiments, the configuration complete message is an RRC reconfiguration complete message.

[0188] In some embodiments, the source DU sends an UL RRC message to the CU, where the UL RRC message includes the RRC reconfiguration complete message.

[0189] S509: The terminal device sends a measurement report to the source DU. Correspondingly, the source DU receives the measurement report from the terminal device.

[0190] 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.

[0191] In some embodiments, the terminal device measures the RS according to the RS configuration, and then sends the measurement results to the source DU according to the CSI resource configuration.

[0192] In some embodiments, before the terminal device sends a 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 timing advance (TA) and associated non-contention random access (CFRA) resource information of the first candidate cell to the source DU via the CU.

[0193] In some embodiments, the terminal device sends a measurement report to a first DU. Correspondingly, the first DU receives the measurement report from the terminal device. The first DU is a different DU 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 considered the source DU of the terminal device.

[0194] S510: The source DU decides to perform LTM handover based on the measurement report. For example, the source DU decides to perform LTM handover on the first candidate cell.

[0195] S511: The source DU sends an LTM cell handover command to the terminal device. Correspondingly, the terminal device receives the LTM cell handover command.

[0196] The LTM cell handover command indicates a first candidate cell as a target cell for handover. The first candidate cell is the target cell. The LTM cell handover command includes an identifier of the target cell.

[0197] In some embodiments, the LTM cell handover command also includes beam information of the target cell (e.g., a time controlled interrupt state (TCI state) identifier) ​​and timing advance information of the target cell. The beam information is used by the terminal device to receive downlink control information in a random access-free manner.

[0198] In some embodiments, the LTM cell switching command is a MAC control element (MAC-CE) message.

[0199] S512: The source DU sends an LTM cell change notification message to the CU. Correspondingly, the CU receives the LTM cell change notification message from the source DU.

[0200] 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 the target cell ID and beam information. It is understood that the target cell is the first candidate cell in the aforementioned step.

[0201] 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.

[0202] 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.

[0203] Optionally, before step S514, the target DU detects terminal access. For example, the terminal device accesses the target DU via random access or random access-free access. If the random access-free access is used, the target DU sends downlink control information to the terminal device based on the beam information. In the random access-free access mode, the terminal device accesses the target cell via PUSCH based on the timing advance information in the LTM cell handover command, rather than accessing the target cell via PRACH.

[0204] After detecting the access of the terminal device, the target DU sends the successful access message to the CU.

[0205] After the CU receives the successful access message from the target DU, it 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 source DU's candidate cell. The source DU sends a UE Context Release Complete message to the CU.

[0206] S514: The terminal device determines the first target time domain position according to the first configuration.

[0207] After accessing the target cell (i.e., 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.

[0208] 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.

[0209] 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.

[0210] Exemplarily, the terminal device determines a third count value based on the first reference SFN and the reception time of the RRC reconfiguration message, and further determines a first target time domain position based on the third count value, the period P, the first reference SFN, and the first offset.

[0211] After the terminal device receives the first configuration, the terminal device determines a first reception time. The first reception time is the time when the first configuration is received. In other words, the first reception time is the time when the RRC reconfiguration message is received.

[0212] In some embodiments, the first receiving time is UTC time. Alternatively, the first receiving time is the SFN, subframe, and symbol of a source cell. The source cell belongs to a source DU. The source cell is the current serving cell of the terminal device.

[0213] After the terminal device determines the first reception time, the terminal device determines a third count value based on the first reception time and the first reference SFN. This third count value is used to determine the number K3 of radio frame periods. This number K3 begins 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 this number K3 corresponds to the first reference SFN, and is, for example, 0.

[0214] 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. The number of radio frames that have passed 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 is 1, and the third count value is 1, and so on.

[0215] Exemplarily, the first reference SFN is before the first receiving time and is closest to the first receiving time.

[0216] 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.

[0217] 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.

[0218] 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:

[0219] (third count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0220] Where N is the radio frame period, M is the duration of a radio frame, and modulo is the modular operation.

[0221] When N is 10240ms and M is 10ms, the above formula is:

[0222] (third count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0223] S515: The target DU determines a first target time domain position according to the first configuration.

[0224] 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.

[0225] Optionally, after determining the first reference SFN, the target DU determines a second count value based on the first reference SFN. The second count value is used to determine the number K2 of radio frame periods, where K2 is counted starting from the time corresponding to the first reference SFN. The initial value of K2 corresponds to the first reference SFN and is, for example, 0.

[0226] For example, assuming that the first reference SFN is 512, the number of radio frame cycles that have elapsed during the period 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. The number of radio frame cycles that have elapsed 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 is 1, and the second count value is 1, and so on.

[0227] 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.

[0228] 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.

[0229] In some embodiments, the first target SFN and the first target subframe number satisfy the following formula:

[0230] (Second count value×N+First target SFN×M+First target subframe number) modulo period P=(First reference SFN×M+First offset) modulo period P.

[0231] Where N is the radio frame period, M is the duration of a radio frame, and modulo is the modular operation.

[0232] When N is 10240ms and M is 10ms, the above formula is:

[0233] (Second count value×10240+First target SFN×10+First target subframe number) modulo period P=(First reference SFN×10+First offset) modulo period P.

[0234] 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.

[0235] Figure 7 is a schematic flow chart of a communication method provided by an embodiment of the present application. The communication method 600 in Figure 7 is executed by the communication system in Figure 1 or Figure 2. Figure 7 includes the following steps.

[0236] S601: The CU sends a third request message to the source DU. Correspondingly, the source DU receives the third request message from the CU.

[0237] 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 for the candidate DU to communicate with the terminal device.

[0238] Optionally, the auxiliary information includes synchronization information. The synchronization information is used for frame synchronization and subframe synchronization between the source DU and the candidate DU. The synchronization information includes radio frame synchronization information and / or subframe synchronization information. The synchronization information is similar to that described in step S401.

[0239] For example, the synchronization information may include a first UTC time and the SFN and subframe number of the source DU corresponding to the first UTC time. The candidate DU may determine the SFN and subframe number of the candidate DU corresponding to the first UTC time based on 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.

[0240] In some embodiments, the third request message is a UE context modification request message.

[0241] S602: The source DU sends third response information to the CU.

[0242] Correspondingly, the CU receives a third response message from the source DU, where the third response message includes the auxiliary information.

[0243] In some embodiments, the third response message is a UE context modification response message.

[0244] S603: The CU sends a first request message to the candidate DU. Correspondingly, the candidate DU receives the first request message from the CU.

[0245] The first request message is used to request the candidate DU to provide a first configuration. The first configuration includes a period P, which is not divisible 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 communication between the candidate DU and the terminal device. The implementation method of step S603 is similar to that of S401.

[0246] 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 at the GAP.

[0247] In some embodiments, the period of the radio frame is the product of a first value and the duration of a radio frame, and the first value is the maximum value of SFN plus 1.

[0248] In some embodiments, the first request message further includes auxiliary information. The auxiliary information is used by the candidate DU to determine the first target time domain position.

[0249] In some embodiments, the first request message is a UE context setup request message.

[0250] S604: The candidate DU sends a first configuration to the CU. Correspondingly, the CU receives the first configuration from the candidate DU.

[0251] 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 that of step S402.

[0252] In some embodiments, the first configuration is carried in a first response message. The first response message is a UE context setup response message.

[0253] S605: The CU sends a first configuration to the source DU. Correspondingly, the source DU receives the first configuration, which includes a period P.

[0254] 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.

[0255] 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.

[0256] 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 and includes a period P.

[0257] 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.

[0258] In some embodiments, the source DU receives a 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.

[0259] S607: The terminal device sends a configuration completion message to the source DU. Correspondingly, the source DU receives the configuration completion message.

[0260] In some embodiments, the configuration complete message is an RRC reconfiguration complete message. The implementation of step S607 is similar to that of step S507.

[0261] S608: The source DU sends a configuration completion message to the CU. Correspondingly, the CU receives the configuration completion message from the source DU.

[0262] In some embodiments, the configuration complete message is an RRC reconfiguration complete message. The implementation of step S608 is similar to that of step S508.

[0263] In some embodiments, the source DU sends an UL RRC message to the CU, where the UL RRC message includes the RRC reconfiguration complete message.

[0264] S609, the terminal device sends a measurement report to the source DU.

[0265] 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 of step S609 is similar to step S509.

[0266] In some embodiments, the terminal device measures the RS according to the RS configuration, and then sends the measurement results to the source DU according to the CSI resource configuration.

[0267] In some embodiments, before the terminal device sends a measurement report, the terminal device and the candidate DU perform early synchronization on the first candidate cell based on 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 via the CU.

[0268] In some embodiments, the terminal device sends a measurement report to a first DU. Correspondingly, the first DU receives the measurement report from the terminal device. The first DU is a different DU 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 considered the source DU of the terminal device.

[0269] S610: The source DU decides to perform LTM switching based on 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.

[0270] S611: The source DU sends a first count value to the CU. Correspondingly, the CU receives the first count value from the source DU.

[0271] The first count value is used to determine the number K1 of radio frame periods. This number K1 is counted starting 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 a second target time domain location. The second target time domain location is the same as the first target time domain location or matches the service characteristics of the terminal device.

[0272] In some embodiments, the source DU determines a third reference SFN and further determines the first count value based on the third reference SFN.

[0273] For example, assuming that the third reference SFN is 512, the number of radio frame cycles that have elapsed during the period 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. The number of radio frame cycles that have elapsed during the period from the first SFN after the third reference SFN being 512 to the second SFN after the third reference SFN being 511 is 1, and the first count value is 1, and so on. The method for determining the first count value is similar to the method for determining the second count value in step S515.

[0274] 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.

[0275] 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. During the expected sending time period, the source DU sends synchronization information to the CU. During the expected receiving time period, the target DU receives the synchronization information. The time period includes at least one time slot. The time period includes at least one time slot.

[0276] 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 the third reference SFN to be 512.

[0277] S612: The CU sends a first count value to the candidate DU. Correspondingly, the candidate DU receives the first count value from the CU.

[0278] After the candidate DU receives the first count value, the candidate DU determines a first reference SFN and / or a first offset based on 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 location. The first offset is an offset corresponding to the first reference SFN.

[0279] Exemplarily, the candidate DU determines the SFN of the source DU within the current radio frame period based on the synchronization information and the first count value. The SFN of the source DU is used to determine the time domain location for communication with the terminal device. The candidate DU determines the SFN of the candidate DU corresponding to the SFN of the source DU based on the synchronization information. The candidate DU determines a first reference SFN and a first offset based on the SFN of the candidate DU. The sum of the first reference SFN and the first offset is the SFN of the candidate DU.

[0280] 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 the first reference SFN can be determined to be 512 and the first offset to be 86.

[0281] 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.

[0282] For example, assuming that the first candidate value set includes 0 and 512, if the SFN corresponding to the third time is 600, since both 0 and 512 are before 600 and 512 is closer to 600 than 0, the candidate DU determines the first reference SFN as 512.

[0283] 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.

[0284] 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.

[0285] S615: The source DU sends an LTM cell switching command to the terminal device. Correspondingly, the terminal device receives the LTM cell switching command.

[0286] The LTM cell handover command indicates a first candidate cell as a target cell for handover. The first candidate cell is the target cell. The LTM cell handover command includes an identifier of the target cell.

[0287] In some embodiments, the LTM cell handover command also includes beam information of the target cell (e.g., a time controlled interrupt state (TCI state) identifier) ​​and timing advance information of the target cell. The beam information is used by the terminal device to receive downlink control information in a random access-free manner.

[0288] In some embodiments, the LTM cell handover 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.

[0289] In some embodiments, the LTM cell handover command is a MAC-CE message.

[0290] S616: The source DU sends an 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.

[0291] 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 the target cell ID and beam information. It is understood that the target cell is the first candidate cell in the aforementioned step.

[0292] In step 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.

[0293] 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.

[0294] Optionally, before step S618, the target DU detects terminal access. For example, the terminal device accesses the target DU via random access or random access-free access. If the random access-free access is used, the target DU sends downlink control information to the terminal device based on the beam information. The random access-free access method is that the terminal device accesses the target cell via PUSCH based on the timing advance information in the LTM cell handover command, rather than accessing the target cell via PRACH.

[0295] After detecting the access of the terminal device, the target DU sends the successful access message to the CU.

[0296] After the CU receives the successful access message from the target DU, it 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 source DU's candidate cell. The source DU sends a UE Context Release Complete message to the CU.

[0297] S618: The terminal device determines a first target time domain position according to the first configuration, the first reference SFN and the first offset.

[0298] After accessing the target cell (i.e., switching to the target DU), the terminal device determines a first target time domain position based on 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.

[0299] 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.

[0300] After the terminal device receives the first reference SFN, the terminal device determines a second reception time. The second reception time is the time when the first reference SFN is received. In other words, the second reception time is the time when the LTM cell switching command is received.

[0301] 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.

[0302] After the terminal device determines the second reception time, it determines a third count value based on the second reception time and the first reference SFN. This third count value is used to determine the number K3 of radio frame periods. This number K3 begins 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 this number K3 corresponds to the first reference SFN, and is, for example, 0. The manner in which the terminal device determines the third count value is similar to that described in step S514 and is not further described here.

[0303] Exemplarily, the first reference SFN is before the second receiving time and is closest to the second receiving time.

[0304] 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:

[0305] (third count value×N+first target SFN×M+first target subframe number) modulo period P=(first reference SFN×M+first offset) modulo period P.

[0306] Where N is the radio frame period, M is the duration of a radio frame, and modulo is the modular operation.

[0307] When N is 10240ms and M is 10ms, the above formula is:

[0308] (third count value×10240+first target SFN×10+first target subframe number) modulo period P=(first reference SFN×10+first offset) modulo period P.

[0309] S619: The target DU determines a first target time domain position according to the first configuration, the first reference SFN, and the first offset.

[0310] 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 the first target SFN and the first target subframe number.

[0311] Optionally, after determining the first reference SFN, the target DU determines a second count value based on the first reference SFN. This second count value is used to determine the number K2 of radio frame periods, which is counted starting from the time corresponding to the first reference SFN. The initial value of K2 corresponds to the first reference SFN and is, for example, 0. The manner in which the target DU determines the second count value is similar to that described in step S515 and is not further described here.

[0312] In some embodiments, the first target SFN and the first target subframe number satisfy the following formula:

[0313] (Second count value×N+First target SFN×M+First target subframe number) modulo period P=(First reference SFN×M+First offset) modulo period P.

[0314] Where N is the radio frame period, M is the duration of a radio frame, and modulo is the modular operation.

[0315] When N is 10240ms and M is 10ms, the above formula is:

[0316] (Second count value×10240+First target SFN×10+First target subframe number) modulo period P=(First reference SFN×10+First offset) modulo period P.

[0317] In an embodiment of the present application, the terminal device determines the number of wireless frame periods 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 periods that have passed, the period P, the first reference SFN and the first bias, and then communicate with the data matching the service of the specific period.

[0318] It is understood that in order to implement the functions in the above embodiments, the terminal device, source DU, and target DU include hardware structures and / or software modules corresponding to the execution of each function. It should be readily apparent to 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 hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0319] Figures 8, 9, and 10 are schematic diagrams of the structures of possible communication devices provided in 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-mentioned method embodiments, and thus can also achieve the beneficial effects possessed by the above-mentioned method embodiments. In the embodiments of the present application, the communication device is the source DU 201 or target DU 203 shown in Figure 2, and is also the terminal device 202 shown in Figure 2.

[0320] As shown in Figure 8, the communication device 700 includes a receiving unit 710 and a sending unit 720. The communication device 700 is used to implement the functions of the target DU or source DU in the method embodiments shown in Figure 5, Figure 6 or Figure 7 above.

[0321] When the communication device 700 is used to implement the functions of the target DU in the method embodiments shown in Figures 5, 6, or 7: 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, where the first response message includes a first configuration. The first request message, first response message, and first configuration are similar to the first request message, first response message, and first configuration in Figures 5, 6, or 7, and are not further described here.

[0322] In some embodiments, when the communication device 700 is used to implement the functions of the target DU in the method embodiment shown in FIG6 , the communication device 700 further includes a processing unit. The processing unit is configured to determine a first reference SFN based on the first time period. The first time period and the first reference SFN are similar to the first time period and the first reference SFN in FIG6 , and are not further described here.

[0323] In some embodiments, when the communication device 700 is used to implement the function of the target DU in the method embodiment shown in Figure 6, the receiving unit 710 is further used to receive time period information from the CU. The time period information is similar to the time period information in Figure 6 and will not be repeated here.

[0324] In some embodiments, when the communication device 700 is used to implement the functions of the target DU in the method embodiment shown in FIG7 , the communication device 700 further includes a processing unit. The receiving unit 710 is further configured to receive a first count value from the CU; the processing unit is further configured to determine a first reference SFN and a first offset based on the first count value; and the sending unit 720 is further configured 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 similar to the first count value, the first reference SFN, and the first offset in FIG7 and are not further described here.

[0325] In some embodiments, when the communication device 700 is used to implement the functions of the target DU in the method embodiment shown in FIG7 , 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 based on the synchronization information and the first count value. This synchronization information is similar to the synchronization information in FIG7 and is not further described here.

[0326] In some embodiments, when the communication device 700 is used to implement the functions of the target DU in the method embodiment shown in Figure 6 or Figure 7, 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 similar to those in Figures 6 and 7 and are not further described here.

[0327] When the communication device 700 is used to implement the functions of the source DU in the method embodiment shown in Figure 6 or Figure 7: the transmitting unit 720 is used to send auxiliary information to the target DU via the CU; the receiving unit 710 is used to receive the RRC reconfiguration message from the CU; and the transmitting unit 720 is further used to send the RRC reconfiguration message to the terminal device. The auxiliary information and RRC reconfiguration message are similar to the auxiliary information and RRC reconfiguration message in Figures 6 and 7, and will not be repeated here.

[0328] In some embodiments, when the communication device 700 is used to implement the functions of the source DU in the method embodiments shown in Figures 6 and 7, the receiving unit 710 is further configured to receive a measurement report from a terminal device; and the sending unit 720 is further configured to send an LTM cell handover command to the terminal device. The measurement report and LTM cell handover command are similar to those in Figures 6 and 7, and are not further described here.

[0329] In some embodiments, when the communication device 700 is used to implement the functions of the source DU in the method embodiment shown in FIG7 , the transmitting unit 720 is further configured to transmit a first count value to the target DU via the CU; and the receiving unit 710 is further configured to receive a first reference SFN and a first offset from the target DU via the CU. The first count value, first reference SFN, and first offset are similar to the first count value, first reference SFN, and first offset in FIG7 and are not further described here.

[0330] For a more detailed description of the above-mentioned receiving unit 710 and sending unit 720, please refer to the relevant description of the method embodiment shown in Figure 5, Figure 6 or Figure 7.

[0331] As shown in Figure 9, the communication device 800 includes a transceiver unit 810 and a processing unit 820. The communication device 800 is used to implement the functions of the terminal device in the method embodiment shown in Figure 6 or Figure 7 above.

[0332] When the communication device 800 is used to implement the functions of the terminal device in the method embodiment shown in Figure 6 or Figure 7: the transceiver unit 810 is used to receive an RRC reconfiguration message from the 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 handover command from the source DU; and the processing unit 820 is used to determine the first target time domain position based on the configuration of the target cell. The RRC reconfiguration message, the configuration of the target cell, the LTM cell handover command, and the first target time domain position are similar to those described in Figure 6 or Figure 7 and are not further described here.

[0333] In some embodiments, when the communication device 800 is used to implement the function of the terminal device in the method embodiment shown in Figure 6: the processing unit 820 is also used to determine the first target time domain position based on the configuration of the target cell and the reception time of the RRC reconfiguration message.

[0334] In some embodiments, when the communication apparatus 800 is used to implement the functions of the terminal device in the method embodiment shown in FIG7 , the processing unit 820 is further configured to determine the first target time domain location based on the configuration of the target cell, the first reference SFN, the first offset, and the time of receipt of the LTM cell handover command. The first reference SFN and the first offset are similar to the first reference SFN and the first offset in FIG7 and are not further described here.

[0335] In some embodiments, when the communication device 800 is used to implement the functions of the terminal device in the method embodiment shown in Figure 6 or Figure 7: the transceiver unit 810 is further used to send a measurement report to the source DU. The measurement report is similar to the measurement report in Figure 6 and Figure 7, and will not be repeated here.

[0336] For a more detailed description of the transceiver unit 810 and the processing unit 820 , please refer to the relevant description of the method embodiment shown in FIG. 6 or FIG. 7 .

[0337] As shown in Figure 10, 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.

[0338] When the communication device 900 is used to implement the method shown in Figure 5, Figure 6 or Figure 7, the processor 910 is used to implement the functions of the above-mentioned processing unit 820, and the interface circuit 920 is used to implement the functions of the above-mentioned receiving unit 710, sending unit 720 or transceiver unit 810.

[0339] When the communication device is a chip used in a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from other modules in the terminal (such as a radio frequency module or 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 antenna), and the information is sent by the terminal to the base station.

[0340] When the above-mentioned communication device is a module applied to a base station (or network equipment), the base station module implements the functions 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 the baseband chip of the base station, or it can be a DU or other module. The DU here can be a DU under the open radio access network (O-RAN) architecture.

[0341] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be 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.

[0342] 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 well 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 an integral part 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.

[0343] In the above embodiments, all or part of the embodiments may be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed 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 instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; an optical medium, such as a digital video disk; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

[0344] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0345] In this application, "at least one" means one or more, and "more" 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 this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship; in the formula of this 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.

[0346] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent 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: (second count value×N+the first target SFN×M+the first target subframe number) modulo the period P=(first reference SFN×M+first offset) 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 offset 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 the first target time domain position, 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 target 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, characterized in that: Includes the communication device as claimed in claim 26, the communication device as claimed in claim 27, and the communication device as claimed in 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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