A communication method and apparatus

Abstract

A communication method and apparatus are disclosed. The method includes: receiving a first time difference from a second communication device; determining a round-trip time (RTT) based on the first time difference and a second time difference; sending a second message to a terminal device, the second message containing the RTT, an air interface propagation delay, or terminal device-side timing information, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the terminal device-side timing information is determined based on the air interface propagation delay. Using the method and apparatus of this application embodiment, high-precision time synchronization between network devices and terminal devices can be achieved in a CU and DU separation architecture.

Description

Technical Field

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

[0002] Mobile internet and the Internet of Things (IoT), as the main driving forces for the future development of communications, have had a tremendous impact on people's living, working, leisure, and transportation. Currently, in order to achieve precise control of services, many fields such as industrial control, smart grids, and autonomous driving require high-precision time synchronization between terminal devices and wireless network clocks, with time synchronization accuracy reaching the microsecond or even nanosecond level.

[0003] Currently, in the Long Term Evolution (LTE) and 5G (5G) era... th In 5G (Generation 5G) communication systems (or new radio, NR), base stations transmit high-precision time information to terminal devices via broadcast or unicast to achieve high-precision time synchronization. Due to transmission delays between the base station and terminal devices, the high-precision time on the terminal device side is actually the result of the base station's high-precision time superimposed with the air interface propagation delay. In one design, the round-trip time (RTT) can be determined by the downlink reception and uplink transmission time difference of the terminal device, and the uplink reception and downlink transmission time difference of the base station, thus determining the air interface propagation delay, where the air interface propagation delay is equal to half the RTT.

[0004] In 5G communication systems, base stations can adopt an architecture that separates centralized units (CUs) and distributed units (DUs) (hereinafter referred to as CU-DU separation architecture). Under the CU-DU separation architecture, how to utilize the time difference between downlink reception and uplink transmission of the terminal device, and the time difference between uplink reception and downlink transmission of the base station, to determine the air interface propagation delay and further achieve high-precision time synchronization between network devices and terminal devices is the technical problem to be solved in the embodiments of this application. Summary of the Invention

[0005] This application provides a communication method and apparatus to achieve high-precision time synchronization between network devices and terminal devices under a CU-DU separation architecture.

[0006] It should be noted that in the following description, the first communication device is a DU or a chip in a DU, the second communication device is a CU or a chip in a CU, and the terminal device can also be a chip in a terminal device. Taking the first communication device as a DU, the second communication device as a CU, and the terminal device as a UE as an example, the following scheme is described.

[0007] In a first aspect, a communication method is provided, the method comprising: a DU receiving a first time difference from a CU, the first time difference being the time difference between a UE receiving a first downlink time unit and transmitting a first uplink time unit; the DU determining a round-trip time (RTT) based on the first time difference and a second time difference, the second time difference being the time difference between the DU receiving the first uplink time unit and transmitting the first downlink time unit; the DU sending a second message to the UE, the second message containing the RTT, an air interface propagation delay, or UE-side timing information, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the UE-side timing information is determined based on the air interface propagation delay.

[0008] Using the above method, the DU can obtain the first time difference from the UE side from the CU. Based on this first time difference and the second time difference from the DU side, it can determine the air interface propagation delay or the UE-side timing information, achieving high-precision timing between the terminal device and the network device in the CU-DU separation architecture. Furthermore, if the DU compensates for the DU-side timing information based on the air interface propagation delay to obtain the UE-side timing information, and directly sends this UE-side timing information to the UE via the aforementioned second message, then the DU directly sends the compensated timing information (i.e., the UE-side timing information) to the UE, eliminating the need for the UE to calculate it itself and reducing UE power consumption. Simultaneously, the DU no longer needs to send network-side timing information separately to the UE, saving signaling overhead.

[0009] Optionally, before the DU receives the first time difference from the CU, the method further includes: the DU sending a first message to the CU, the first message being used to request the first time difference; or, the DU sending a second indication message to the UE, the second indication message being used to instruct the UE to report the first time difference.

[0010] In one possible design, the first message is used to request the first time difference, specifically including: the first message requesting the CU to send the first time difference to the DU upon receiving the first message; or, the first message includes a first period, the first period being the period during which the CU sends the first time difference to the DU. Optionally, the first message may further include indication information indicating that the CU stops periodically sending the first time difference to the DU.

[0011] Using the above method, the CU can determine the difference between the current first time difference and the first time difference sent last time. If the difference is greater than a predefined threshold, the CU will no longer send the first time difference to the DU. This avoids the DU frequently sending the first time difference to the CU and saves signaling overhead.

[0012] Secondly, a communication method is provided, the method comprising: a CU receiving a first time difference from a UE, the first time difference being the time difference between the UE receiving a first downlink time unit and transmitting a first uplink time unit; the CU sending the first time difference to a DU, the first time difference being used by the DU to determine a second message, the second message including round-trip time (RTT), air interface propagation delay, or UE-side timing information, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the UE-side timing information is determined based on the air interface propagation delay.

[0013] Using the above method, the CU can obtain the first time difference of the UE and send the first time difference to the DU. Finally, the DU determines the air interface propagation delay, or directly uses the air interface propagation delay to compensate for the timing information on the DU side, thus realizing high-precision timing between network devices and terminal devices under the CU-DU architecture.

[0014] Optionally, before the CU receives the first time difference from the UE, the method further includes: the CU sending first indication information to the UE, the first indication information being used to instruct the UE to report the first time difference.

[0015] In one possible design, the first indication information includes: the UE reporting the period of the first time difference to the CU; or, the UE reporting the triggering event of the first time difference to the CU.

[0016] Optionally, the first indication information may further include: cell information corresponding to the first time difference reported by the UE.

[0017] It should be indicated that if the first indication information mentioned above does not include cell information, the UE may report the first time difference of a predefined cell to the CU. The predefined cell may be a primary cell, a primary secondary cell, or a secondary cell, etc.

[0018] In one possible design, the triggering event includes at least one of the following: the change between the first time difference currently measured by the UE and the first time difference previously reported is greater than or equal to a first threshold; the first time difference currently measured by the UE is greater than or equal to a second threshold.

[0019] The above method can avoid the UE frequently reporting the first time difference to the CU, thus saving signaling overhead.

[0020] Optionally, the method further includes: the CU receiving cell information from the UE corresponding to the first time difference.

[0021] Optionally, before sending the first time difference to the DU, the method further includes: the CU receiving a first message from the DU, the first message being used to request the first time difference.

[0022] In one possible design, the first message is used to request the first time difference, specifically including: the first message requests the CU to send the first time difference to the DU when it receives the first message; or, the first message includes a first period, the first period being the period during which the CU sends the first time difference to the DU.

[0023] Thirdly, a communication method is provided, comprising: a UE sending a first time difference to a CU, the first time difference being the time difference between the UE receiving a first downlink time unit and sending a first uplink time unit; the UE receiving a second message from a DU, the second message containing a round-trip time (RTT), an air interface propagation delay, or UE-side timing information, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the UE-side timing information is determined based on the air interface propagation delay.

[0024] Using the above method, if the DU directly sends the UE-side timing information to the UE, the UE does not need to calculate the UE-side timing information itself, thus reducing the UE's power consumption.

[0025] Optionally, before the UE sends the first time difference to the CU, the method further includes: the UE receiving first indication information from the CU, the first indication information being used to instruct the UE to report the first time difference; or, the UE receiving second indication information from the DU, the second indication information being used to instruct the UE to report the first time difference.

[0026] Fourthly, a communication method is provided, the method comprising: a CU receiving a first time difference from a UE, the first time difference being the time difference between the UE receiving a first downlink time unit and transmitting a first uplink time unit; the CU receiving a second time difference from a DU, the second time difference being the time difference between the DU receiving the first uplink time unit and transmitting the first downlink time unit; the CU determining a round-trip time (RTT) based on the first time difference and the second time difference; and the CU sending a fourth message to the UE, the fourth message containing the RTT, an air interface propagation delay, or UE-side timing information, wherein the UE-side timing information is determined based on the air interface propagation delay, and the value of the air interface propagation delay is equal to half the value of the RTT.

[0027] Using the above method, the CU obtains the first time difference from the UE and the second time difference from the DU. Based on the first and second time differences, the air interface propagation delay or the UE-side timing information is determined, thereby achieving high-precision timing between network devices and terminal devices under the CU-DU separation architecture.

[0028] Optionally, before receiving the first time difference from the UE, the method further includes: the CU sending first indication information to the UE, the first indication information being used to instruct the UE to report the first time difference.

[0029] In one possible design, the first indication information includes: the UE reporting the period of the first time difference to the CU; or, the UE reporting the triggering event of the first time difference to the CU.

[0030] Optionally, the first indication information may further include: cell information corresponding to the first time difference reported by the UE.

[0031] In one possible design, the triggering event includes at least one of the following: the change between the first time difference currently measured by the UE and the first time difference previously reported is greater than or equal to the first threshold; the first time difference currently measured by the UE is greater than or equal to the second threshold.

[0032] Optionally, the method further includes: the CU receiving cell information from the UE corresponding to the first time difference.

[0033] Optionally, before receiving the second time difference from the DU, the method further includes: the CU sending a third message to the DU, the third message being used to request the second time difference.

[0034] In one possible design, the third message is used to request the second time difference, specifically including: the third message requests the DU to send the second time difference to the CU when it receives the second message; or, the third message includes a second period, which is the period during which the DU sends the second time difference to the CU.

[0035] Fifthly, a communication method is provided, comprising: a DU determining a second time difference, the second time difference being the time difference between the DU receiving a first uplink time unit and transmitting a first downlink time unit; and the DU transmitting the second time difference to a CU.

[0036] Using the above method, the DU sends the second time difference from the DU side to the CU, so that the CU can determine the air interface propagation delay or the UE-side timing information based on the second time difference, thereby satisfying the high-precision timing between network devices and terminal devices under the CU-DU architecture.

[0037] Optionally, before sending the second time difference to the CU, the method further includes: the DU receiving a third message from the CU, the third message being used to request the second time difference.

[0038] In one possible design, the third message is used to request the second time difference, specifically including: the third message requests the DU to send the second time difference to the CU when it receives the third message; or, the second message includes a second period, which is the period during which the DU sends the second time difference to the CU.

[0039] A sixth aspect provides a communication method, comprising: a UE sending a first time difference to a CU, the UE receiving a fourth message from the CU, the fourth message being determined based on the first time difference, the fourth message including the RTT, air interface propagation delay or UE-side timing information, the UE-side timing information being determined based on the air interface propagation delay, the value of the air interface propagation delay being equal to half the value of the RTT.

[0040] Using the above method, the UE sends the first time difference from the UE side to the CU, so that the CU can determine the air interface propagation delay or the UE side timing information based on the first time difference, thereby satisfying the high-precision timing between network devices and terminal devices under the CU-DU architecture.

[0041] Optionally, before the UE sends the first time difference to the CU, the method further includes: the UE receiving first indication information from the CU, the first indication information being used to instruct the UE to report the first time difference.

[0042] In one possible design, the first indication information includes: the UE reporting the period of the first time difference to the CU; or, the UE reporting the triggering event of the first time difference to the CU.

[0043] Optionally, the first indication information may further include: cell information corresponding to the first time difference reported by the UE.

[0044] In one possible design, the triggering event includes at least one of the following: the change between the first time difference currently measured by the UE and the first time difference previously reported is greater than or equal to the first threshold; the first time difference currently measured by the UE is greater than or equal to the second threshold.

[0045] Optionally, the above also includes: the UE reporting cell information corresponding to the first time difference to the CU.

[0046] A seventh aspect provides a communication method, comprising: a CU receiving a second time difference from a DU, the second time difference being the time difference between the DU receiving a first uplink time unit and transmitting a first downlink time unit; the CU transmitting the second time difference to a UE, the second time difference being used by the UE to determine the air interface propagation delay.

[0047] Using the above method, the CU notifies the UE of the second time difference on the DU side. The UE determines the air interface propagation delay based on the second time difference, thus saving signaling overhead on the CU side or the DU side.

[0048] Optionally, before receiving the second time difference from the DU, the method further includes: the CU receiving a first request from the UE, the first request being used to request the second time difference.

[0049] Optionally, the first request may include the cell information corresponding to the second time difference.

[0050] Optionally, before the CU receives the second time difference from the DU, the method further includes: the CU sending a third message to the DU, the third message being used to request the second time difference.

[0051] In one possible design, the third message is used to request the second time difference, specifically including: the third message requests the DU to send the second time difference to the CU when it receives the third message; or, the second message includes a third period, the third period being the period during which the DU sends the second time difference to the CU.

[0052] Optionally, the method further includes: the CU sending cell information corresponding to the second time difference to the UE.

[0053] Eighthly, a communication method is provided, comprising: a DU determining a second time difference, the second time difference being the time difference between the DU receiving a first uplink time unit and transmitting a first downlink time unit; and the DU transmitting the second time difference to a CU.

[0054] Optionally, before the DU sends the second time difference to the CU, the method further includes: the DU receiving a third message from the CU, the third message being used to request the second time difference.

[0055] In one possible design, the third message is used to request the second time difference, specifically including: the third message requests the DU to send the second time difference to the CU when it receives the third message; or, the third message includes a second period, the second period being the period during which the DU sends the second time difference to the CU.

[0056] A ninth aspect provides a communication method, comprising: a UE receiving a first time difference from a CU, the first time difference being the time difference between the CU receiving a first uplink time unit and transmitting a first downlink time unit; and the UE determining an air interface propagation delay based on the first time difference and a second time difference.

[0057] Using the above method, when the CU receives a request for the second time difference, the CU directly triggers the DU to send the second time difference to the UE, without having to forward it through the CU, thus saving signaling overhead.

[0058] Optionally, before the UE receives the first time difference from the CU, the method further includes: sending a first message to the CU, the first message being used to request the first time difference.

[0059] Optionally, the first message may also include cell information corresponding to the first time difference.

[0060] A tenth aspect provides a communication method, comprising: a CU receiving a first request from a UE, the first request being used to request a DU to receive a second time difference between a first uplink time unit and a first downlink time unit; the CU sending a fifth message to the DU, the fifth message being used to request the DU to send the second time difference to the UE.

[0061] Optionally, the fifth message carries cell information corresponding to the second time difference.

[0062] In one possible design, the fifth message is used to request the DU to send the second time difference to the UE. Specifically, the fifth message includes: the fifth message instructing the DU to send the second time difference to the UE when it receives the fifth message; or, the fifth message includes a third period, which is the period during which the DU sends the second time difference to the UE.

[0063] Eleventhly, a communication method is provided, comprising: a DU receiving a fifth message from a CU, the fifth message being used to request the DU to send a second time difference to the UE, the second time difference being the time difference between the DU receiving a first uplink time unit and sending a first downlink time unit; and sending the second time difference to the UE, the second time difference being used to determine the air interface propagation delay.

[0064] Optionally, the method further includes: the DU sending cell information corresponding to the second time difference to the UE.

[0065] In a twelfth aspect, a communication method is provided, comprising: a UE receiving a second time difference from a DU, the second time difference being the time difference between the DU receiving a first uplink time unit and transmitting a first downlink time unit; the UE determining an air interface propagation delay based on the first time difference and the second time difference, the first time difference being the time difference between the UE receiving the first downlink time unit and transmitting the first uplink time unit.

[0066] Optionally, before the UE receives the second time difference from the DU, the method further includes: the UE sending a first request to the CU, the first request being used to request the second time difference.

[0067] In a thirteenth aspect, a communication apparatus is provided, including means for implementing any one of the first to twelfth aspects described above.

[0068] In a fourteenth aspect, a communication device is provided, including a processor and an interface circuit. The interface circuit is configured to receive signals from other communication devices outside the communication device and transmit them to the processor, or to send signals from the processor to other communication devices outside the communication device. The processor is configured to implement the methods in any of the implementations of the first to twelfth aspects via logic circuits or execution code instructions.

[0069] In a fifteenth aspect, a computer-readable storage medium is provided, which stores a computer program or instructions that, when executed, implement the method in any of the implementations of the first to twelfth aspects.

[0070] In a sixteenth aspect, a computer program product containing instructions is provided, which, when executed, implement the method of any of the implementations of the first to twelfth aspects described above.

[0071] In a seventeenth aspect, a chip system is provided, comprising a processor and potentially a memory, for implementing the methods described in any of the first and twelfth aspects. The chip system may be composed of chips or may include chips and other discrete devices. Attached Figure Description

[0072] Figure 1 A schematic diagram of the network architecture provided in the embodiments of this application;

[0073] Figure 2a , Figure 2b , Figure 2c and Figure 2d A schematic diagram of the protocol stack provided in an embodiment of this application;

[0074] Figure 3A schematic diagram illustrating the calculation of air interface propagation delay for a UE, provided in an embodiment of this application;

[0075] Figure 4 A schematic diagram illustrating the calculation of air interface propagation delay by gNB as provided in an embodiment of this application;

[0076] Figure 5 A schematic diagram illustrating the first time difference and the second time difference provided in the embodiments of this application;

[0077] Figure 6 This is a schematic diagram illustrating the transmission of DU-side timing information via SIB according to an embodiment of this application.

[0078] Figure 7 and Figure 8 This is a flowchart of the communication method corresponding to Embodiment 1 of this application;

[0079] Figure 9 and Figure 10 This is a flowchart of the communication method corresponding to Embodiment 2 of this application;

[0080] Figure 11 This is a flowchart of the communication method corresponding to Embodiment 3 of this application;

[0081] Figure 12 This is a flowchart of the communication method corresponding to Embodiment 4 of this application;

[0082] Figure 13 A schematic diagram of MAC layer messages provided in an embodiment of this application;

[0083] Figure 14 and Figure 15 This is a schematic diagram of the device provided in an embodiment of this application. Detailed Implementation

[0084] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0085] Figure 1 This is a schematic diagram of a network architecture applicable to an embodiment of this application. For example... Figure 1 As shown, a terminal device (such as terminal device 1301 or terminal device 1302) can access the wireless network to obtain services from the external network (such as the Internet) or communicate with other devices, such as other terminal devices. This wireless network includes a radio access network (RAN) and a core network (CN). The RAN is used to connect terminal devices to the wireless network, while the CN is used to manage the terminal devices and provide a gateway for communication with the external network.

[0086] The following sections respectively address... Figure 1 The terminal equipment, RAN, and CN involved are described in detail.

[0087] I. Terminal Equipment

[0088] Terminal equipment includes devices that provide voice and / or data connectivity to users, such as handheld devices with wireless connectivity or processing devices connected to a wireless modem. The terminal equipment can communicate with the core network via a radio access network (RAN) and exchange voice and / or data with the RAN. The terminal equipment can include user equipment (UE), wireless terminal equipment, mobile terminal equipment, device-to-device (D2D) terminal equipment, vehicle-to-everything (V2X) terminal equipment, machine-to-machine / machine-type communications (M2M / MTC) terminal equipment, internet of things (IoT) terminal equipment, subscriber unit, subscriber station, mobile station, remote station, access point (AP), remote terminal, access terminal, user terminal, user agent, or user device, etc. For example, this can include mobile phones (or "cellular" phones), computers with mobile terminal devices, and portable, pocket-sized, handheld, or computer-embedded mobile devices. Examples include Personal Communication Service (PCS) phones, cordless phones, Session Initiation Protocol (SIP) phones, Wireless Local Loop (WLL) stations, and Personal Digital Assistants (PDAs). It also includes limited devices, such as those with low power consumption, limited storage capacity, or limited computing power. Examples include information sensing devices such as barcode scanners, radio frequency identification (RFID), sensors, Global Positioning System (GPS), and laser scanners.

[0089] 2. RAN

[0090] The RAN may include one or more RAN devices, such as RAN device 1101 and RAN device 1102. The interface between the RAN device and the terminal device may be a Uu interface (or air interface). Of course, in future communications, the names of these interfaces may remain unchanged or may be replaced by other names, and this application does not limit this.

[0091] RAN equipment refers to nodes or devices that connect terminal devices to a wireless network. RAN equipment can also be called network equipment or base stations. Examples of RAN equipment include, but are not limited to: next-generation NodeBs (gNBs), evolved NodeBs (eNBs), radio network controllers (RNCs), node Bs (NBs), base station controllers (BSCs), base transceiver stations (BTSs), home base stations (e.g., home evolved nodeBs or home node Bs, HNBs), baseband units (BBUs), transmitting and receiving points (TRPs), transmitting points (TPs), and mobile switching centers in 5G communication systems.

[0092] (1) Protocol layer structure

[0093] Communication between RAN devices and terminal devices follows a certain protocol layer structure. For example, the control plane protocol layer structure may include the functions of protocol layers such as radio resource control (RRC), packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical layer. The user plane protocol layer structure may include the functions of protocol layers such as PDCP, RLC, MAC, and physical layer. In one possible implementation, a service data adaptation protocol (SDAP) layer may also be included above the PDCP layer.

[0094] Taking data transmission between network devices and terminal devices as an example, data transmission needs to pass through user plane protocol layers, such as SDAP, PDCP, RLC, MAC, and physical layers. These layers can also be collectively referred to as the access layer. Based on the direction of data transmission, it is divided into sending and receiving; each of the above layers is further divided into a sending part and a receiving part. See the following data transmission example. Figure 2a The diagram shows the transmission of downlink data between layers. Figure 2a Downward arrows indicate data transmission, while upward arrows indicate data reception. After receiving data from the upper layer, the PDCP layer transmits the data to the RLC and MAC layers. The MAC layer then generates transport blocks, which are then wirelessly transmitted through the physical layer. Data is encapsulated in each layer. Data received by a layer from the upper layer is considered a service data unit (SDU) for that layer. After layer encapsulation, it becomes a PDU and is then passed to the next layer.

[0095] For example, according to Figure 2a It can also be seen that the terminal device has an application layer and a non-access layer. The application layer can provide services to applications installed on the terminal device. For example, downlink data received by the terminal device can be sequentially transmitted from the physical layer to the application layer, and then provided to the application by the application layer. Alternatively, the application layer can acquire data generated by the application and sequentially transmit the data to the physical layer for transmission to other communication devices. The non-access layer can be used to forward user data, such as forwarding uplink data received from the application layer to the SDAP layer or forwarding downlink data received from the SDAP layer to the application layer.

[0096] (2) CU and DU

[0097] In this embodiment, the RAN device may include a CU and DUs, and multiple DUs may be centrally controlled by a single CU. As an example, the interface between the CU and DUs may be called an F1 interface, where the control plane (CP) interface may be F1-C and the user plane (UP) interface may be F1-U. The CU and DU can be distinguished according to the protocol layer of the wireless network: for example... Figure 2b As shown, the functionalities of the PDCP layer and above are configured in the CU, while the functionalities of the protocol layers below the PDCP layer (such as the RLC layer and MAC layer) are configured in the DU; for example... Figure 2c As shown, the functional settings of the protocol layers above the PDCP layer are configured in the CU, and the functional settings of the protocol layers at and below the PDCP layer are configured in the DU.

[0098] It is understood that the above division of CU and DU processing functions according to protocol layers is merely an example. Other division methods are also possible. For instance, CU or DU can be divided into functions with more protocol layers, or they can be divided into partial processing functions with protocol layers. In one design, some functions of the RLC layer and the functions of the protocol layers above the RLC layer are located in the CU, while the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer are located in the DU. In another design, the functions of CU or DU can be divided according to service type or other system requirements, such as by latency. Functions whose processing time needs to meet latency requirements are located in the DU, while functions that do not need to meet this latency requirement are located in the CU. In yet another design, the CU can also have one or more core network functions. For example, the CU can be located on the network side for convenient centralized management; the DU can have multiple radio frequency functions, or the radio frequency functions can be remotely located. This application does not limit this aspect.

[0099] For example, the functionality of a CU can be implemented by a single entity, or it can be implemented by different entities. For instance, such as... Figure 2d As shown, the functions of the CU can be further divided, that is, the control plane and the user plane can be separated and implemented through different entities, namely the control plane CU entity (i.e., the CU-CP entity) and the user plane CU entity (i.e., the CU-UP entity). The CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the functions of the RAN device.

[0100] It should be noted that: in the above Figures 2b to 2d In the illustrated architecture, signaling generated by the CU can be sent to the terminal device via the DU, or signaling generated by the terminal device can be sent to the CU via the DU. The DU can directly encapsulate the signaling through the protocol layer and transmit it to the terminal device or CU without parsing it. In the following embodiments, if such signaling transmission between the DU and the terminal device is involved, the DU's sending or receiving of signaling includes this scenario. For example, RRC or PDCP layer signaling will eventually be processed into physical layer signaling and sent to the terminal device, or it may be transformed from received physical layer signaling. In this architecture, the RRC or PDCP layer signaling can also be considered as being sent by the DU, or by the DU and the radio frequency device.

[0101] III. CN

[0102] A CN can include one or more CN devices, for example, CN device 120. Taking a 5G communication system as an example, a CN can include access and mobility management function (AMF) network elements, session management function (SMF) network elements, user plane function (UPF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, and application function (AF) network elements, etc.

[0103] It should be understood that Figure 1 The number of devices in the communication system shown is for illustrative purposes only. This application embodiment is not limited to this. In actual applications, the communication system may include more terminal devices, more RAN devices, and other devices.

[0104] The above Figure 1 The illustrated network architecture is applicable to various radio access technology (RAT) communication systems, such as 4G (or LTE) communication systems, 5G (or NR) communication systems, or transitional systems between LTE and 5G communication systems (also known as 4.5G communication systems). It can also be used in future communication systems, such as 6G communication systems. The network architecture and service scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that with the evolution of communication network architectures and the emergence of new service scenarios, the technical solutions provided in this application are equally applicable to similar technical problems.

[0105] The relevant technical features involved in the embodiments of this application will be explained below. It should be noted that these explanations are for the purpose of making the embodiments of this application easier to understand, and should not be regarded as a limitation on the scope of protection claimed by this application.

[0106] I. High-precision time synchronization

[0107] In LTE or NR systems, the base station transmits high-precision time information to the UE via broadcast or unicast to achieve high-precision time synchronization. Due to the transmission delay between the base station and the UE, the high-precision time on the UE side is actually superimposed on the high-precision time information transmitted to the base station side due to the propagation delay.

[0108] In one possible design, the round-trip time (RTT) can be determined by the time difference between the UE's downlink reception and uplink transmission (hereinafter referred to as: downlink reception-uplink transmission time difference) and the time difference between the base station's uplink reception and downlink transmission (hereinafter referred to as: uplink reception-downlink transmission time difference), where RTT = (gNB reception-transmission time difference) + (UE reception-transmission time difference), thereby determining the air interface propagation delay RTT / 2. The air interface propagation delay accuracy obtained in this way is approximately within 100 ns (nanoseconds), which is relatively high.

[0109] II. The process of determining RTT

[0110] In the current scheme, there are two methods for determining RTT. The first method involves the gNB sending the uplink receive-downlink transmit time difference of a cell to the UE. The UE then determines the RTT based on the uplink receive-downlink transmit time difference from the gNB and the downlink receive-uplink transmit time difference of the UE in that cell. For example... Figure 3 As shown, a possible process is provided, including:

[0111] - The UE sends uplink frame i and records the uplink frame i transmission time T1.

[0112] -gNB receives uplink frame i and records the arrival time T3 of uplink frame i.

[0113] -gNB sends downlink frame j to the UE and records the downlink frame j transmission time T2.

[0114] - The UE receives downlink frame j and records the arrival time of downlink frame j, T4.

[0115] -gNB sends the receive-transmit time difference (T3-T2) to the UE. This time difference can be positive or negative.

[0116] It depends on whether the gNB sends the downlink frame before or after receiving the uplink frame.

[0117] - The UE determines the air interface propagation delay, which is calculated using the formula: RTT = (gNB receive-transmit time difference) + (UE receive-transmit time difference); where the gNB receive-transmit time difference is T3-T2, and the UE receive-transmit time difference is T4-T1. Assuming symmetrical uplink and downlink propagation delays, the one-way air interface propagation delay is RTT / 2.

[0118] The second approach involves the UE sending its receive-transmit time difference (RTD) within a cell to the gNB. The gNB then determines the air interface propagation delay based on the UE's RTD and its own RTD within the cell, and sends this delay back to the UE. For example... Figure 4 As shown, a possible process is provided, including:

[0119] - The UE sends uplink frame i and records the uplink frame i transmission time T1.

[0120] -gNB receives uplink frame i and records the arrival time T3 of uplink frame i.

[0121] -gNB sends downlink frame j to the UE and records the downlink frame j transmission time T2.

[0122] - The UE receives downlink frame j and records the arrival time of downlink frame j, T4.

[0123] - The UE sends the UE receive-transmit time difference (T4-T1) to the base station. The value of this time difference can be positive or negative, depending on whether the UE sends the uplink frame before or after receiving the downlink frame.

[0124] -gNB calculates the air interface propagation delay using the formula: RTT = (gNB receive-transmit time difference) + (UE receive-transmit time difference). Assuming symmetrical uplink and downlink propagation delays, the one-way air interface propagation delay is RTT / 2.

[0125] -gNB sends the air interface propagation delay to the UE.

[0126] It should be noted that, to facilitate understanding of the relationship between RTT and air interface propagation delay, the above formula can be slightly derived: RTT = (gNB receives uplink frame i - gNB sends downlink frame j) + (UE receives downlink frame j - UE sends uplink frame i) = (gNB receives uplink frame i - UE sends uplink frame i) + (UE receives downlink frame j - gNB sends downlink frame j) = twice the air interface propagation delay. Therefore, in this embodiment, the air interface propagation delay can be determined using the reception and transmission times of any uplink and downlink frame; the values ​​of i and j can be the same or different.

[0127] In the above Figure 1 In the network architecture shown, there is currently no solution for determining the air interface propagation delay and further achieving high-precision time synchronization between terminal devices and the wireless network side in scenarios where the CU and DU are separated.

[0128] Based on the above, this application provides the following solution: Since the DU includes the receive-transmit time difference on the DU side, and the UE includes the receive-transmit time difference on the UE side, this application provides the following solution:

[0129] Option 1: The DU can obtain the receive-transmit time difference from the UE side. The DU determines the air interface propagation delay based on both, as described in Example 1 below.

[0130] Option 2: The CU can obtain the receive-transmit time difference from the DU side and the receive-transmit time difference from the UE side. The CU determines the air interface propagation delay based on both, as described in the following Example 2.

[0131] Option 3: The CU can obtain the receive-transmit time difference from the DU side and send it to the UE. The UE determines the air interface propagation delay based on the receive-transmit time difference from the DU side, as described in Example 3 below.

[0132] Option 4: The UE can send a first message to the CU to obtain the DU receive-transmit time difference. After receiving the first message, the CU sends a second message to the DU. After receiving the second message, the DU sends the DU-side receive-transmit time difference to the UE. See the description in Example 4 below.

[0133] Option 5: The DU or CU can send an indication message to the UE, instructing the UE to report the UE-side receive-transmit time difference to the DU; the DU receives the UE-side receive-transmit time difference from the UE, and the DU determines the air interface propagation delay based on this time difference.

[0134] It should be noted that in the following description:

[0135] 1. The first communication device can be a DU or a chip in the DU, the second communication device can be a CU or a chip in the CU, and the terminal device can be a terminal device or a chip in the terminal device.

[0136] 2. The UE's receive-transmit time difference is called the first time difference, which is specifically the time difference between the UE receiving the first downlink time unit and transmitting the first uplink time unit. The DU's receive-transmit time difference is called the second time difference, which is specifically the time difference between the DU receiving the first uplink time unit and transmitting the first downlink time unit.

[0137] Optionally, the time unit in the embodiments of this application can be a radio frame, a subframe, a slot, a mini-slot, or a symbol, etc. In the following description, a subframe is used as an example of the time unit.

[0138] like Figure 5As shown, if the gNB sends downlink subframe 3 and the UE sends uplink subframe 3, then the UE's receive-transmit time difference is the time difference between the UE receiving downlink subframe 3 and sending uplink subframe 3, and the gNB's receive-transmit time difference is the time difference between the gNB receiving uplink subframe 3 and sending downlink subframe 3.

[0139] 3. DU-side timing information refers to the reference time of the frame boundary of a radio frame or subframe on the base station side, which can be understood as the time before propagation delay compensation. UE-side timing information refers to the reference time of the boundary of a radio frame or subframe on the UE side, which can be understood as the time after air interface propagation delay compensation. In this embodiment, the DU-side timing information can be sent to the UE by the DU, or sent to the UE by the CU. If sent to the UE by the CU, the CU needs to obtain the aforementioned DU-side timing information from the DU in advance. The DU-side timing information can also be referred to as network-side timing information.

[0140] Optionally, the DU-side timing information includes at least one of the following:

[0141] -DU side reference time

[0142] -Number of days relative to the start time

[0143] - seconds value

[0144] -millisecond value

[0145] Values ​​in units of -10 nanoseconds

[0146] The reference time on the DU side represents the reference time relative to the agreed start time point, which is equal to: number of days.

[0147] *86400*1000*100000+seconds*1000*100000+milliseconds*100000+ten nanoseconds, where the unit is nanoseconds.

[0148] -Reference system frame number (SFN)

[0149] - Clock type: Local clock or Global Positioning System (GPS) clock

[0150] - Error value; Optionally, if an error value is included, the UE can determine its timing information based on the error value and the DU-side reference time. In other words, the UE-side timing information needs to consider not only the impact of air interface propagation delay but also the impact of the aforementioned error value.

[0151] In one example, the DU or CU can broadcast DU-side timing information to the UE. This DU-side timing information does not need to carry the aforementioned reference SFN; the reference SFN can be implicitly indicated through the broadcast message. For example, as... Figure 6 As shown, the DU-side timing information is sent through the system information block (SIB) 16. The boundary position of the SFN100 carrying the SIB 16 is the position of the DU reference time indicated by the aforementioned DU-side timing information.

[0152] In another example, the DU or CU can use unicast to send DU-side timing information to the UE using dedicated signaling. The aforementioned DU-side timing information needs to carry the aforementioned reference SFN.

[0153] 4. In the following Embodiment 1 and Embodiment 2, the information sent by the CU to the UE to instruct the UE to report the first time difference is referred to as the first indication information. The first indication information may be, but is not limited to:

[0154] SIB, Master Information Block (MIB), RRC Reconfiguration, RRC Resume, Downlink (DL) Information Transfer, RRC Reestablishment, DL Information Transfer (Multi-rat Dual Connectivity, MRDC), Logged Measurement Configuration, UE Information Request, Mobility from NR Command, or Measurement Configuration.

[0155] For example, the first instruction information mentioned above includes any of the following:

[0156] - The period during which the UE reports the first time difference to the CU; or

[0157] - The UE reports the triggering event of the first time difference to the CU; optionally, the triggering event includes any of the following:

[0158] -The change between the first time difference currently measured by the UE and the first time difference previously reported is greater than or equal to the first threshold;

[0159] -The first time difference currently measured by the UE is greater than or equal to the second threshold;

[0160] -The difference between the first time difference and the hysteresis value currently measured by the UE is greater than or equal to the third gate.

[0161] The hysteresis value is limited and the duration for which it is continuously satisfied is greater than T. Optionally, the hysteresis value can be a parameter used in the entry and exit conditions of the event triggering reporting condition.

[0162] Optionally, the first indication information may also include cell information corresponding to the first time difference. This cell information can be a primary cell (Pcell), a primary secondary cell (PScell), or a secondary cell (Scell), etc. If the first indication information does not carry cell information, the UE can report the first time difference of a predefined cell, which can be a Pcell, PScell, or Scell, etc., without limitation.

[0163] 5. In the following Embodiment 1 and Embodiment 2, the first time difference sent by the UE to the CU according to the above-mentioned first indication information can be carried in any of the following messages: UE assistance information message, measurement report message, RRC reconfiguration complete message, RRC reestablishment complete message, RRC resumecomplete message, uplink information transfer message, UE information response message, or uplink information transfer multi-mode dual connectivity (MRDC) message, etc.

[0164] Optionally, in addition to sending the first time difference to the CU, the UE can also send the cell information corresponding to the first time difference to the CU. Optionally, if the UE does not send the cell information corresponding to the first time difference to the CU, the CU may assume that the UE is reporting the first time difference of a predefined cell, such as a Pcell, PScell, or Scell. The UE can determine the difference between the currently measured first time difference and the previously sent first time difference; if the difference is less than a predefined threshold, the UE will no longer send the first time difference to the CU. This avoids the UE frequently sending the first time difference to the CU, reducing signaling overhead. The predefined threshold for the first time difference can be configured for the UE by the CU or DU, for example, the predefined threshold for the first time difference can be carried in the first indication information.

[0165] It should be noted that the following naming convention is used in the following Embodiment 1 and Embodiment 2. In Embodiment 1, please refer to... Figure 7 The message sent by the DU to the CU to request the first time difference is called the first message. The message sent by the DU to the UE carrying RTT, air interface propagation delay, or terminal device-side timing information is called the second message. See Embodiment 2 for details. Figure 9 The message sent by the CU to the DU to request the second time difference is called the third message. The message sent by the CU to the UE carrying RTT, air interface propagation delay, or terminal device-side timing information is called the fourth message.

[0166] In addition, see also Figure 11 As shown, since Embodiment 3 also involves the process of the CU requesting a second time difference from the DU, the message sent by the CU to the DU to request the second time difference retains the naming convention from Embodiment 2 and is still called the third message. It is noted that although Embodiment 4 below also involves the process of the CU requesting a second time difference from the DU, the CU actually requests the DU to send the second time difference to the UE. Therefore, this request message is different from the request messages in Embodiments 2 and 3 above. Therefore, the above command is no longer used, and the message in Embodiment 4 where the CU requests the DU to send the second time difference to the UE is called the fifth message. See [link to related documentation]. Figure 12 As shown.

[0167] Example 1

[0168] This application provides a communication method, including: a first communication device receiving a first time difference from a second communication device; the first communication device determining an RTT based on the first time difference and a second time difference; and the first communication device sending the RTT, an air interface propagation delay, or terminal device-side timing information to a terminal device, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the terminal device-side timing information is determined based on the air interface propagation delay.

[0169] In the following description, the terminal device is UE, the first communication device is DU, and the second communication device is CU, as an example, to describe the scheme in the embodiments of this application. Figure 7 As shown, a flow chart of a communication method is provided, including:

[0170] Optionally, in step 701: the CU sends a first indication information to the UE, the first indication information being used to instruct the UE to report the UE's receive-transmit time difference, i.e., the first time difference.

[0171] Step 702: The UE sends the first time difference to the CU.

[0172] Optionally, in step 703: DU sends a first message to CU, which is used to request a first time difference.

[0173] The first message includes, but is not limited to: reference time information reporting message, uplink RRC message transfer message, UE context setup response message, or UE context modification response message, etc.

[0174] Optionally, the first message is used to request a first time difference, specifically including: the first message requesting the CU to send a first time difference to the DU when it receives the first message; or the first message includes a first period, where the first period is the period during which the CU sends the first time difference to the DU. Optionally, the first message may also include: an indication that the CU stops sending the first time difference to the DU, etc.

[0175] Optionally, step 701 above can also be replaced by: the DU sending a second indication information to the UE, the second indication information being used to instruct the UE to report the first time difference to the CU.

[0176] The second indication information may be, but is not limited to, SIB, MIB, downlink control information (DCI), or MAC layer messages.

[0177] Step 704: CU sends the first time difference to DU.

[0178] The aforementioned first time difference can be carried in any of the following messages: reference time information reporting control message, downlink RRC message transfer message, UE context setup request message, or UE context modification request message, etc.

[0179] Step 705: The DU sends a second message to the UE, which includes RTT, air interface propagation delay, or UE-side timing information. Optionally, the second message may include, but is not limited to, DCI or downlink MAC layer signaling.

[0180] Example 1: The second message sent by the DU to the UE contains RTT or air interface propagation delay.

[0181] In Example 1, the DU can determine the RTT based on the first time difference and the second time difference; the DU can directly send the RTT to the UE, and the UE can subsequently determine the air interface propagation delay based on the RTT and use the air interface propagation delay to compensate for the timing on the network side. Alternatively, the DU can directly send the air interface propagation delay to the UE.

[0182] In this example, if the DU sends the air interface propagation delay to the UE, the DU can determine the difference between the current air interface propagation delay and the previously sent air interface propagation delay. If the difference is lower than a predefined threshold, the DU can stop sending the air interface propagation delay to the UE. Similarly, if the DU sends the RTT to the UE, the DU can determine the difference between the current RTT and the previously sent RTT. If the difference is lower than a predefined threshold, the DU can stop sending the RTT to the UE. This avoids the DU frequently sending the air interface propagation delay or RTT to the UE, reducing signaling overhead. The predefined thresholds for the air interface transmission delay or RTT can be configured by the CU for the DU and are not limited.

[0183] In Example 1, such as Figure 8 As shown, in addition to steps 701 to 705 described above, the following steps may also be included:

[0184] Step 706: The DU sends DU-side timing information to the UE. Alternatively, step 706 can be replaced by: the CU sending DU-side timing information to the UE.

[0185] Step 707: The UE compensates for the DU-side timing information based on the RTT or air interface propagation delay received in step 705 above, and obtains the UE-side timing information.

[0186] The UE-side timing information is equal to the sum of the DU-side timing information and the air interface propagation delay. Optionally, the UE can also provide UE-side timing information to the application layer.

[0187] In Example 1 above, the CU obtains the first time difference from the UE and sends the first time difference to the DU; the DU determines the RTT or air interface propagation delay based on the first time difference and the second time difference, and sends the RTT or air interface propagation delay to the UE. The DU determines the RTT or air interface propagation delay to reduce the power consumption of the UE.

[0188] Example 2: The second message sent by the DU to the UE contains UE-side timing information, which is determined based on the air interface propagation delay.

[0189] Optionally, before sending UE-side timing information to the UE via the second message, the DU can determine the difference between the current UE-side timing information and the previously sent UE-side timing information. If the difference is less than a predefined threshold, the DU will no longer send UE-side timing information to the UE. This avoids the DU frequently sending UE-side timing information to the UE and saves signaling overhead.

[0190] In Example 2, after determining the RTT based on the first and second time differences, the DU obtains the air interface propagation delay. Based on the air interface propagation delay, the DU compensates for the DU-side timing information to obtain the UE-side timing information. This UE-side timing information is then directly sent to the UE. Thus, the DU directly sends the compensated timing information (i.e., the UE-side timing information) to the UE, eliminating the need for the UE to calculate it itself and reducing UE power consumption. Simultaneously, the DU no longer needs to separately send network-side timing information to the UE, saving signaling overhead.

[0191] Example 2

[0192] The method includes: a second communication device receiving a first time difference from a terminal device; the second communication device receiving a second time difference from a first communication device; the second communication device determining the RTT based on the first time difference and the second time difference; and the second communication device sending the RTT, air interface propagation delay, or terminal device-side timing information to the terminal device, wherein the terminal device-side timing information is determined based on the air interface propagation delay.

[0193] like Figure 9As shown, taking the first communication device as DU, the second communication device as CU, and the terminal device as UE as an example, a communication method flow is provided, which includes at least:

[0194] Optionally, in step 901: the CU sends a first indication information to the UE, which is used to instruct the UE to report the first time difference.

[0195] Step 902: The UE sends the first time difference to the CU.

[0196] Optionally, in step 903: the CU sends a third message to the DU, which is used to request a second time difference.

[0197] The third message may be, but is not limited to, any of the following: reference time information report control message, downlink RRC message transmission message, UE context establishment request message, or UE context modification request message, etc.

[0198] Optionally, the third message is used to request the second time difference, specifically including: the third message is used to request the DU to send the second time difference to the CU when it receives the third message; or, the third message includes a second period, which is the period during which the DU sends the second time difference to the CU. Optionally, the third message may also include: an indication that the DU stops periodically reporting the second time difference to the CU, and / or, cell information corresponding to the second time difference.

[0199] Step 904: DU sends the second time difference to CU.

[0200] The second time difference is carried in any of the following messages: reference time information report message, uplink RRC message transmission message, UE context establishment response message, or UE context modification response message, etc.

[0201] Optionally, the DU can also send cell information corresponding to the second time difference to the CU. This cell information and the second time difference can be carried in the same or different messages, without limitation. Optionally, if the DU does not send cell information corresponding to the second time difference to the CU, the DU can assume that the received second time difference belongs to a predefined cell, which can be a Pcell, Pscell, or Scell, etc., without limitation. The DU can determine the difference between the current second time difference and the previously reported second time difference. If the difference is less than a predefined threshold, the DU will no longer send the second time difference to the CU, thus avoiding the DU frequently sending the second time difference to the CU. The aforementioned predefined threshold for the second time difference can be configured by the CU for the DU.

[0202] Step 905: The CU sends a fourth message to the UE, which includes RTT, air interface propagation delay, or UE-side timing information. This fourth message can be, but is not limited to, any of the following:

[0203] DCI, RRC connection establishment, RRC reconfiguration message, RRC connection recovery message, downlink information transmission message, RRC re-establishment message, downlink information transmission multi-standard dual-connection message, log measurement configuration message, UE information request message, handover command message, or measurement configuration message, etc.

[0204] Example 1: The fourth message in step 905 above contains RTT or air interface propagation delay.

[0205] In Example 1, after obtaining the first time difference and the second time difference from the UE and the CU respectively, the CU can determine the RTT based on the first time difference and the second time difference, and can directly indicate the RTT to the UE; or, the CU can also determine the air interface propagation delay based on the RTT and indicate the air interface propagation delay to the UE, etc., without limitation.

[0206] Optionally, the CU can determine the difference between the current RTT and the last transmitted RTT; if the difference is less than or equal to a predefined threshold, the CU will no longer send RTT or air interface propagation delay to the UE, thus avoiding the CU frequently sending RTT or air interface propagation delay to the UE and saving signaling overhead.

[0207] In Example 1 above, such as Figure 10 As shown, in addition to steps 901 to 905 described above, the method may also include:

[0208] Step 906: The DU sends DU-side timing information to the UE. Alternatively, step 906 can be replaced with: the CU sends DU-side timing information to the UE.

[0209] Step 907: The UE determines the UE-side timing information based on the DU-side timing information and the air interface propagation delay. Optionally, the UE-side timing information is equal to the sum of the DU-side timing information and the air interface propagation delay.

[0210] Example 2: The fourth message in step 905 above contains UE-side timing information.

[0211] Optionally, before sending UE-side timing information to the UE via the fourth message, the CU can determine the difference between the current UE-side timing information and the previously sent UE-side timing information. If the difference is less than a predefined threshold, the CU will no longer send UE-side timing information to the UE. This avoids the CU frequently sending UE-side timing information to the UE and saves signaling overhead.

[0212] In Example 2, after determining the air interface propagation delay, the CU determines the UE-side timing information based on the air interface propagation delay and the DU-side timing information, and directly instructs the UE-side timing information to the UE. Thus, the UE does not need to calculate the UE-side timing information itself, saving UE power consumption. Simultaneously, the CU does not need to send the DU-side timing information to the UE, saving signaling overhead.

[0213] Example 3

[0214] The method includes: a second communication device receiving a second time difference from a first communication device; the second communication device sending the second time difference to a terminal device, the second time difference being used by the terminal device to determine the air interface propagation delay.

[0215] like Figure 11 As shown, a flow chart of a communication method is provided. Taking a first communication device as DU, a second communication device as CU, and a terminal device as UE as an example, it includes at least the following:

[0216] Optionally, in step 1101: the UE sends a first request to the CU, which is used to request a second time difference.

[0217] Optionally, the first request in step 1101 above can also be replaced with: whether the UE supports the ability to receive the second time difference; if the UE supports receiving the second time difference, then the DU or CU can send the second time difference to the UE; otherwise, it will not send the second time difference to the UE. Or,

[0218] Does the UE expect to obtain a second time difference? Similarly, if the UE expects to obtain a second time difference, the DU or CU will send the second time difference to the UE; otherwise, it will not send the second time difference to the UE.

[0219] The first request mentioned above may be, but is not limited to: UE auxiliary information message, measurement report message, RRC reconfiguration completion message, RRC re-establishment completion message, RRC recovery completion message, uplink information transmission message, UE information response message, or uplink information transmission multi-mode dual-connection message, etc.

[0220] Optionally, the first request may include cell information corresponding to the second time difference. If the first request does not include cell information corresponding to the second time difference, the CU or DU may send the second time difference of a predefined cell to the UE, wherein the predefined cell may be Pcell, Pscell, or Scell, etc.

[0221] Optionally, in step 1102: the CU sends a third message to the DU, which requests a second time difference. Similar to the above, the third message can also be replaced with: whether the UE supports receiving the second time difference, or whether the UE expects to receive the second time difference, etc.

[0222] Step 1103: DU sends the second time difference to CU.

[0223] For detailed procedures of steps 1102 and 1103 above, please refer to the above. Figure 9 The details recorded therein will not be repeated here.

[0224] Step 1104: The CU sends the second time difference to the UE.

[0225] Optionally, the second time difference may be carried in any of the following messages: RRC connection establishment, RRC reconfiguration message, RRC connection recovery message, downlink information transmission message, RRC re-establishment message, downlink information transmission multi-mode dual-connection message, log measurement configuration message, UE information request message, handover command message, or measurement configuration message, etc.

[0226] Optionally, the CU may also send cell information corresponding to the second time difference to the UE. This cell information and the aforementioned second time difference may be carried in the same message or in different messages, without limitation.

[0227] Step 1105: The UE determines the air interface propagation delay based on the second time difference and the first time difference. Optionally, the UE may compensate for the timing information on the DU side based on the air interface propagation delay.

[0228] Example 4

[0229] The method includes: a second communication device receiving a first request from a terminal device, the first request being used to request a second time difference; and the second communication device sending the second time difference to a first communication device.

[0230] like Figure 12 As shown, taking the first communication device as DU, the second communication device as CU, and the terminal device as UE as an example, a communication method flow is provided, which includes at least:

[0231] Step 1201: The UE sends a first request to the CU, which requests a second time difference. See step 1101 above for details on step 1201.

[0232] Step 1202: The CU sends a fifth message to the DU, which requests the DU to send the second time difference to the UE. Similarly, the fifth message can also be replaced with: whether the UE supports receiving the second time difference, or whether the UE expects to receive the second time difference, etc.

[0233] Optionally, the fifth message may be, but is not limited to: a reference time information report control message, a downlink RRC message transmission message, a UE context establishment request message, or a UE context modification request message, etc.

[0234] The fifth message is used to request the DU to send a second time difference to the UE. Specifically, the fifth message includes: the fifth message instructs the DU to send the second time difference to the UE when it receives the fifth message; or, the fifth message includes a third period, which is the period during which the DU sends the second time difference to the UE.

[0235] Step 1203: The DU sends a second time difference to the UE according to the fifth message. Optionally, this second time difference can be carried in the DCI or MAC layer signaling.

[0236] Taking MAC layer signaling as an example, such as Figure 13 As shown, the MAC layer signaling includes a MAC subheader and a MAC control element (CE). The MAC subheader includes field 1, carrying a logical channel identity document (LCH ID) to indicate the type of the MAC CE associated with the MAC subheader. The MAC CE carries information indicating a second time difference. For example, the MAC CE may include field 2, carrying information indicating the second time difference. Optionally, the MAC CE may also include field 3, carrying cell information indicating the second time difference.

[0237] Optionally, the DU can determine the difference between the current second time difference and the last transmitted second time difference; if the difference is less than a predefined threshold, the DU will no longer transmit the second time difference to the UE, thus avoiding the DU frequently transmitting the second time difference to the UE and saving signaling overhead.

[0238] Step 1204: The UE determines the air interface propagation delay based on the second time difference and the first time difference. Optionally, the UE can use the air interface propagation delay to compensate for the timing information on the DU side.

[0239] Using the above method, when the CU receives a request for the second time difference, the CU directly triggers the DU to send the second time difference to the UE, without having to forward it through the CU, thus saving signaling overhead.

[0240] Optionally, in one approach, the UE can directly request a second time difference from the DU. Upon receiving the request, the DU directly sends the second time difference to the UE. The entire process requires no CU involvement, resulting in lower signaling overhead. In this approach, steps 1201 to 1203 can be replaced by: the UE sending a second request to the DU, which requests the second time difference; and the DU sending the second time difference to the UE. The second request can be MAC layer signaling or physical layer signaling, etc. The second request is similar to the first request in step 1101 and can be referred to accordingly; further details are omitted.

[0241] The above primarily describes the solutions provided by the embodiments of this application from the perspective of device interaction. It is understood that, to achieve the above functions, the CU or DU may include corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0242] Figure 14 and Figure 15 The diagram illustrates the possible communication devices provided in the embodiments of this application. These communication devices can be used to implement the functions of the CU or DU in the above method embodiments. In the embodiments of this application, the communication device can be the CU or DU in the above method embodiments, or it can be a module (such as a chip) applied in the CU or DU.

[0243] like Figure 14 As shown, the device 1400 includes a processing unit 1401 and a communication unit 1402. The communication device 1400 is used to implement the above-mentioned... Figures 7 to 12 The functions of CU or DU in the method embodiments shown.

[0244] When the communication device 1400 is used to achieve the above Figure 7 or Figure 8 In the method embodiment shown, the DU functions as follows: Communication unit 1402 is used to receive a first time difference from the second communication device, the first time difference being the time difference between the terminal device receiving a first downlink time unit and sending a first uplink time unit; processing unit 1401 is used to determine the round-trip time (RTT) based on the first time difference and the second time difference, the second time difference being the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; communication unit 1402 is also used to send a second message to the terminal device, the second message containing the RTT, air interface propagation delay, or terminal device-side timing information, wherein the value of the air interface propagation delay is equal to half the value of the RTT, and the terminal device-side timing information is determined based on the air interface propagation delay.

[0245] When the communication device 1400 is used to achieve the above Figure 7 or Figure 8In the method embodiment shown, the CU functions as follows: the communication unit 1402 is used to receive a first time difference from the terminal device, the first time difference being the time difference between the terminal device receiving a first downlink time unit and sending a first uplink time unit; the communication unit 1402 is also used to send the first time difference to the first communication device, the first time difference being used by the first communication device to determine a second message, the second message containing round-trip time (RTT), air interface propagation delay, or terminal device-side timing information, the value of the air interface propagation delay being equal to half the value of the RTT, and the terminal device-side timing information being determined based on the air interface propagation delay.

[0246] When the communication device 1400 is used to achieve the above Figure 9 or Figure 10 In the method embodiment shown, the CU functions as follows: Communication unit 1402 is used to receive a first time difference from the terminal device, the first time difference being the time difference between the terminal device receiving a first downlink time unit and sending a first uplink time unit; Communication unit 1402 is also used to receive a second time difference from the first communication device, the second time difference being the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; Processing unit 1401 is used to determine the round-trip time (RTT) based on the first and second time differences; Communication unit 1402 is also used to send a fourth message to the terminal device, the fourth message containing the RTT, air interface propagation delay, or terminal device-side timing information, the terminal device-side timing information being determined based on the air interface propagation delay, the value of the air interface propagation delay being equal to half the value of the RTT.

[0247] When the communication device 1400 is used to achieve the above Figure 9 or Figure 10 In the method embodiment shown, when DU functions, the processing unit 1401 is used to determine a second time difference, which is the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; the communication unit 1402 is used to send the second time difference to the second communication device.

[0248] When the communication device 1400 is used to achieve the above Figure 11 In the method embodiment shown, when the CU functions, the communication unit 1402 is used to receive a second time difference from the first communication device, the second time difference being the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; the communication unit 1402 is also used to send the second time difference to the terminal device, the second time difference being used by the terminal device to determine the air interface propagation delay.

[0249] When the communication device 1400 is used to achieve the above Figure 11 In the method embodiment shown, when DU functions, the processing unit 1401 is used to determine a second time difference, which is the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; the communication unit 1402 is used to send the second time difference to the second communication device.

[0250] When the communication device 1400 is used to achieve the above Figure 12 In the method embodiment shown, when the CU functions, the communication unit 1402 is used to receive a first request from the terminal device, the first request being used to request the first communication device to receive a second time difference between a first uplink time unit and a first downlink time unit; the communication unit 1402 is also used to send a fifth message to the first communication device, the fifth message being used to request the first communication device to send the second time difference to the terminal device.

[0251] When the communication device 1400 is used to achieve the above Figure 12 In the method embodiment shown, when DU functions, the communication unit 1402 is used to receive a fifth message from the second communication device. The fifth message is used to request the first communication device to send a second time difference to the terminal device. The second time difference is the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit. The communication unit 1402 is also used to send the second time difference to the terminal device. The second time difference is used to determine the air interface propagation delay.

[0252] For a more detailed description of the processing unit 1401 and the communication unit 1402, please refer to the above. Figures 7 to 12 The descriptions in the illustrated method embodiments will not be repeated here.

[0253] like Figure 15 As shown, the communication device 1500 includes a processor 1510 and an interface circuit 1520. The processor 1510 and the interface circuit 1520 are coupled to each other. It is understood that the interface circuit 1520 can be a transceiver or an input / output interface. Optionally, the communication device 1500 may also include a memory 1530 for storing instructions executed by the processor 1510, or storing input data required by the processor 1510 to execute instructions, or storing data generated after the processor 1510 executes instructions.

[0254] When the communication device 1500 is used to achieve Figures 7 to 12 In the method shown, the processor 1510 is used to implement the functions of the processing unit 1401, and the interface circuit 1520 is used to implement the functions of the communication unit 1402.

[0255] When the aforementioned communication device is a chip applied to a CU, the CU chip implements the functions of the CU in the above method embodiments. The CU chip receives information from other modules (such as radio frequency modules or antennas) in the CU, which is sent to the CU by a DU or terminal device; or, the CU chip sends information to other modules (such as radio frequency modules or antennas) in the CU, which is sent to the DU or terminal device by the CU.

[0256] When the aforementioned communication device is a chip applied to a DU, the DU chip implements the functions of the DU in the above method embodiments. The DU chip receives information from other modules in the DU (such as an RF module or antenna), which is sent to the DU by the CU or terminal device; or, the DU chip sends information to other modules in the DU (such as an RF module or antenna), which is sent to the CU or terminal device by the DU.

[0257] It is understood that the processor in the embodiments of this application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor.

[0258] In embodiments of this application, the processor may be a random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), register, hard disk, portable hard disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium may also be a component of the processor. The processor and storage medium may reside in an ASIC. Furthermore, the ASIC may reside in a CU, DU, or terminal device. Alternatively, the processor and storage medium may exist as discrete components in a CU, DU, or terminal device.

[0259] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially 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 this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a terminal device, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a DVD; or it can be a semiconductor medium, such as a solid-state disk (SSD).

[0260] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0261] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, The method is applicable to a second communication device, which is a centralized unit (CU) or a chip within the CU, comprising: The first time difference is received from the terminal device, where the first time difference is the time difference between the terminal device receiving the first downlink time unit and sending the first uplink time unit. Receive a second time difference from a first communication device, the second time difference being the time difference between the first communication device receiving a first uplink time unit and sending a first downlink time unit, the first communication device being a distribution unit DU or a chip in a DU; The round-trip time (RTT) is determined based on the first time difference and the second time difference, wherein the RTT is equal to the sum of the first time difference and the second time difference; A fourth message is sent to the terminal device. The fourth message contains the RTT, air interface propagation delay, or terminal device-side timing information. The terminal device-side timing information is determined based on the air interface propagation delay, and the value of the air interface propagation delay is equal to half the value of the RTT.

2. The method as described in claim 1, characterized in that, Before receiving the first time difference from the terminal device, the method further includes: Send a first instruction message to the terminal device, the first instruction message being used to instruct the terminal device to report the first time difference.

3. The method as described in claim 2, characterized in that, The first indication information includes: The terminal device reports the period of the first time difference to the second communication device; or... The terminal device reports the triggering event of the first time difference to the second communication device.

4. The method as described in claim 3, characterized in that, The first indication information also includes: The cell information corresponding to the first time difference reported by the terminal device.

5. The method as described in claim 3, characterized in that, The triggering event includes at least one of the following: The change between the first time difference currently measured by the terminal device and the first time difference previously reported is greater than or equal to a first threshold. The first time difference currently measured by the terminal device is greater than or equal to the second threshold.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: Receive cell information from the terminal device corresponding to the first time difference.

7. The method according to any one of claims 1 to 5, characterized in that, Before receiving the second time difference from the first communication device, the method further includes: A third message is sent to the first communication device, the third message being used to request the second time difference.

8. The method as described in claim 7, characterized in that, The third message is used to request the second time difference, specifically including: The third message requests the first communication device to send the second time difference to the second communication device upon receiving the second message; or, The third message includes a second period, which is the period during which the first communication device sends the second time difference to the second communication device.

9. A communication method, characterized in that, The method is applicable to a first communication device, which is a distribution unit (DU) or a chip within the DU, comprising: Determine a second time difference, which is the time difference between the first communication device receiving the first uplink time unit and sending the first downlink time unit; The second time difference is sent to a second communication device, which is a centralized unit (CU) or a chip in the CU, and the second time difference is used by the second communication device to determine the round-trip time (RTT).

10. The method as described in claim 9, characterized in that, Before sending the second time difference to the second communication device, the method further includes: A third message is received from the second communication device, the third message being used to request the second time difference.

11. The method as described in claim 10, characterized in that, The third message is used to request the second time difference, specifically including: The third message requests the first communication device to send the second time difference to the second communication device upon receiving the third message; or, The second message includes a second period, which is the period during which the first communication device sends the second time difference to the second communication device.

12. A communication method, characterized in that, The method is applicable to a second communication device, which is a centralized unit (CU) or a chip within the CU, comprising: Receive a second time difference from a first communication device, the second time difference being the time difference between the first communication device receiving a first uplink time unit and transmitting a first downlink time unit, the first communication device being a distribution unit DU or a chip in a DU; The second time difference is sent to the terminal device, and the second time difference is used by the terminal device to determine the air interface propagation delay.

13. The method as described in claim 12, characterized in that, Before receiving the second time difference from the first communication device, the method further includes: A first request is received from the terminal device, the first request being used to request the second time difference.

14. The method as described in claim 13, characterized in that, The first request includes the cell information corresponding to the second time difference.

15. The method according to any one of claims 12 to 14, characterized in that, Before receiving the second time difference from the first communication device, the method further includes: A third message is sent to the first communication device, the third message being used to request the second time difference.

16. The method as described in claim 15, characterized in that, The third message is used to request the second time difference, specifically including: The third message requests the first communication device to send the second time difference to the second communication device upon receiving the third message; or, The second message includes a third period, which is the period during which the first communication device sends the second time difference to the second communication device.

17. The method according to any one of claims 12, 13, 14, or 16, characterized in that, The method further includes: The cell information corresponding to the second time difference is sent to the terminal device.

18. A communication device, characterized in that, It includes modules for performing the method as described in any one of claims 1 to 8, or modules for performing the method as described in any one of claims 9 to 11, or modules for performing the method as described in any one of claims 12 to 17.

19. A communication device, characterized in that, It includes a processor and a memory coupled together, the processor being used to implement the method as described in any one of claims 1 to 8, or the method as described in any one of claims 9 to 11, or the method as described in any one of claims 12 to 17.

20. A communication device, characterized in that, The device includes a processor and an interface circuit. The interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor, or to send signals from the processor to other communication devices outside the communication device. The processor is used to implement the method as described in any one of claims 1 to 8, or the method as described in any one of claims 9 to 11, or the method as described in any one of claims 12 to 17, through logic circuits or execution code instructions.

21. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 8, or the method as described in any one of claims 9 to 11, or the method as described in any one of claims 12 to 17.

22. A communication system, characterized in that, Includes means for performing the method as described in any one of claims 1 to 8, and means for performing the method as described in any one of claims 9 to 11.

23. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when the computer program or instructions are run, execute the method as described in any one of claims 1 to 8, or execute the method as described in any one of claims 9 to 11, or execute the method as described in any one of claims 12 to 17.

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