Clock synchronization method and device

Abstract

The present application provides a clock synchronization method and device. In the technical solution of the present application, by simultaneously carrying information that can directly or indirectly indicate a first timestamp and a second timestamp in a third message, the timestamp exchange between the network device and the first terminal can be realized through three messages. In this way, the time interval between the first message and the second message can be shortened, and only three LBTs need to be performed, which can reduce the number of LBTs performed. Therefore, the technical solution of the embodiment of the present application helps to improve the accuracy of clock offset estimation, thereby improving the accuracy of clock synchronization.

Description

Technical Field

[0001] The present application relates to the field of communications, and more specifically, to a clock synchronization method and device. Background Art

[0002] High reliability and low latency wireless transmission are critical in industrial applications to ensure timely and reliable transmission of important information between machines and monitoring equipment. In factory automation applications, multiple robots work together and require synchronization with an accuracy of 1us. Therefore, clock synchronization of the communication network becomes critical.

[0003] In traditional communication networks, clock synchronization of communication networks can be achieved based on the precision time protocol (PTP). PTP exchanges timestamps between master nodes and slave nodes through four messages carrying timestamps to achieve clock synchronization between the master node and the slave node.

[0004] In unlicensed bands, communication devices need to perform (listen before talk, LBT) to listen to the idle state of the channel before transmitting a message carrying a timestamp. In PTP, the need for four messages carrying timestamps means that four LBTs need to be performed. Due to the uncertain delay caused by LBT, the symmetry of the uplink / downlink channels may be affected, resulting in errors in the clock offset estimation. Summary of the invention

[0005] The present application provides a clock synchronization method and device, which help to improve the accuracy of clock synchronization.

[0006] In a first aspect, the present application provides a clock synchronization method, the method comprising:

[0007] The network device sends a first message to the first terminal;

[0008] The network device receives a second message sent by the first terminal;

[0009] The network device sends a third message to the first terminal, and the third message includes first information. The first information is determined based on a first timestamp and a second timestamp. The first timestamp indicates the moment when the network device sends the first message, and the second timestamp indicates the moment when the network device receives the second message.

[0010] In the present application, by simultaneously carrying information that can directly or indirectly indicate the first timestamp and the second timestamp in the third message, the timestamp exchange between the network device and the first terminal can be realized through three messages. In this way, the time interval between the first message and the second message can be shortened, and only three LBTs need to be performed, which can reduce the number of LBTs performed. Therefore, the technical solution of the embodiment of the present application helps to improve the accuracy of clock offset estimation, thereby improving the accuracy of clock synchronization.

[0011] In combination with the first aspect, in a possible implementation, the method also includes: the network device sends second information to the first terminal, the second information is used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is the first time domain resource, and the frequency domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is different from the first frequency domain resource.

[0012] Due to the unlicensed frequency band of 5G, there may be multiple terminals that need to maintain accurate clock synchronization with network devices. If PTP is used to achieve clock synchronization between multiple terminals and network devices, each terminal needs to exchange timestamps with the network device separately, which makes clock synchronization time-consuming. In this application, the same time domain resources and different frequency domain resources are allocated to terminals belonging to the same terminal group, so that multiple terminals can exchange timestamps with network devices at the same time, which helps to reduce the total clock synchronization time of multiple terminals.

[0013] In combination with the first aspect or any one of its implementations, in another possible implementation, the method also includes: the network device divides N terminals into G terminal groups, the N terminals include the first terminal, N is an integer greater than 1, and G is a positive integer less than N.

[0014] In combination with the first aspect or any one of its implementations, in another possible implementation, the network device divides N terminals into G terminal groups, including: the network device divides the N terminals into the G terminal groups according to at least one of service priority, terminal attributes and clock synchronization accuracy requirements.

[0015] For example, terminals that complete the same task can be grouped into one terminal group.

[0016] For another example, terminals with similar moving speeds are grouped into one terminal group.

[0017] For another example, terminals with the same clock synchronization accuracy requirements are grouped into one terminal group.

[0018] For another example, terminals that send the same signal are grouped into one terminal group.

[0019] For another example, terminals having oscillators with the same stability are grouped into one terminal group.

[0020] For another example, a clustering algorithm may be used to comprehensively consider service priority, terminal attributes, and clock synchronization accuracy requirements when grouping.

[0021] In the above technical solution, the network device groups N terminals according to at least one of service priority, terminal attributes and clock synchronization accuracy requirements, which helps the terminals to collaborate in performing tasks.

[0022] In combination with the first aspect or any one of its implementations, in another possible implementation, the network device divides the N terminals into the G terminal groups according to at least one of the service priority, terminal characteristics and clock synchronization accuracy requirements, including: the network device divides the N terminals into the G terminal groups according to at least one of the service priority, terminal attributes and clock synchronization accuracy requirements, and at least one feedback information from the N terminals, and the feedback information is used to indicate whether the clock synchronization accuracy of the previous synchronization cycle meets the requirements.

[0023] Alternatively, the feedback information may indicate a clock synchronization accuracy requirement or a time-frequency resource allocation requirement for the next synchronization cycle.

[0024] In the above technical solution, the terminal can provide feedback to the network device on whether the current clock synchronization accuracy or resource allocation meets the requirements, so that the network device can better group and allocate time-frequency resources.

[0025] In combination with the first aspect or any one of its implementations, in another possible implementation, when the service priority of the first terminal group is higher than the service priority of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two of the G terminal groups; and / or, when the clock synchronization accuracy requirement of the first terminal group is higher than the clock synchronization requirement of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two of the G terminal groups.

[0026] That is, the terminal group with the highest service priority or clock synchronization accuracy requirement is given priority to send the second message.

[0027] Considering that the smaller the time interval between the first message and the second message, the better the symmetry of the uplink channel and the downlink channel, it is helpful to reduce the clock offset estimation error and improve the clock synchronization accuracy. Therefore, in the above technical scheme, the network device can first schedule the terminal group with the highest terminal attributes, service priority or clock synchronization accuracy requirements among the G terminal groups to send the second message, and finally schedule the terminal group with the lowest terminal attributes, service priority or clock synchronization accuracy requirements to send the second message. In this way, the time interval between the second message sent by the terminal group with the highest clock synchronization accuracy requirements and the first message is the shortest, which is conducive to achieving high-precision clock synchronization, while the time interval between the second message sent by the terminal group with the lowest clock synchronization accuracy requirements and the first message is the longest, which can achieve lower-precision clock synchronization. In this way, the clock synchronization accuracy requirements of each terminal can be met.

[0028] In combination with the first aspect or any one of its implementations, in another possible implementation, the second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent via broadcast, and the frequency domain resource allocation information is sent via unicast.

[0029] In combination with the first aspect or any one of its implementations, in another possible implementation, the method further includes: the network device sends third information to the first terminal, and the third information is used to indicate the terminal group to which the first terminal belongs.

[0030] In combination with the first aspect or any one of its implementations, in another possible implementation, the third information includes a group number G, a group number of a terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate a position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

[0031] In combination with the first aspect or any one of its implementations, in another possible implementation, the first information includes the first timestamp and the second timestamp;

[0032] or, when the first message includes an estimated timestamp of when the network device sends the first message, the first information includes a first offset value and the second timestamp, and the first offset value is a difference between the first timestamp and the estimated timestamp;

[0033] Or, the first information includes a third timestamp, and the third timestamp is the sum of the first offset value and the second timestamp;

[0034] Or, the first information includes a fourth timestamp, a second offset value and the first offset value, the fourth timestamp is an average value of timestamps of the second messages respectively sent by multiple terminals received by the network device, the multiple terminals are terminals in a terminal group to which the first terminal belongs, and the second offset value is a difference between the second timestamp and the fourth timestamp;

[0035] Or, the first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

[0036] In combination with the first aspect or any one of its implementations, in another possible implementation, the first timestamp is sent by broadcast, and the second timestamp is sent by unicast; or, the first offset value and the second timestamp are sent by unicast; or, the first offset value is sent by broadcast, and the second timestamp is sent by unicast; or, the third timestamp is sent by unicast; or, the fourth timestamp and the first offset value are sent by broadcast, and the second offset value is sent by unicast; or, the fifth timestamp is sent by broadcast, and the second offset value is sent by unicast.

[0037] In a second aspect, the present application provides a clock synchronization method, the method comprising:

[0038] The first terminal receives a first message sent by the network device;

[0039] The first terminal sends a second message to the network device;

[0040] The first terminal receives a third message sent by the network device, where the third message includes first information, where the first information is determined according to a first timestamp and a second timestamp, where the first timestamp indicates a time when the network device sends the first message, and the second timestamp indicates a time when the network device receives the second message;

[0041] The first terminal performs clock synchronization with the network device according to a sixth timestamp, a seventh timestamp and the first information, the sixth timestamp indicating the time when the first terminal receives the first message, and the seventh timestamp indicating the time when the first terminal sends the second message.

[0042] In the present application, by simultaneously carrying information that can directly or indirectly indicate the first timestamp and the second timestamp in the third message, the timestamp exchange between the network device and the first terminal can be realized through three messages. In this way, the time interval between the first message and the second message can be shortened, and only three LBTs need to be performed, which can reduce the number of LBTs performed. Therefore, the technical solution of the embodiment of the present application helps to improve the accuracy of clock offset estimation, thereby improving the accuracy of clock synchronization.

[0043] In combination with the second aspect, in a possible implementation, the method also includes: the first terminal receives second information sent by the network device, the second information is used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resources corresponding to the terminal belonging to the same terminal group as the first terminal are the first time domain resources, and the frequency domain resources corresponding to the terminal belonging to the same terminal group as the first terminal are different from the first frequency domain resources.

[0044] Due to the unlicensed frequency band of 5G, there may be multiple terminals that need to maintain accurate clock synchronization with network devices. If PTP is used to achieve clock synchronization between multiple terminals and network devices, each terminal needs to exchange timestamps with the network device separately, which makes clock synchronization time-consuming. In this application, the same time domain resources and different frequency domain resources are allocated to terminals belonging to the same terminal group, so that multiple terminals can exchange timestamps with network devices at the same time, which helps to reduce the total clock synchronization time of multiple terminals.

[0045] In combination with the second aspect or any one of its implementations, in another possible implementation, the second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent via broadcast, and the frequency domain resource allocation information is sent via unicast.

[0046] In combination with the second aspect or any one of its implementations, in another possible implementation, the method further includes: the first terminal receives third information sent by the network device, and the third information is used to indicate the terminal group to which the first terminal belongs.

[0047] In combination with the second aspect or any one of its implementations, in another possible implementation, the third information includes a group number G, a group number of a terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate a position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

[0048] In combination with the second aspect or any one of its implementations, in another possible implementation, the first information includes the first timestamp and the second timestamp;

[0049] or, when the first message includes an estimated timestamp of when the network device sends the first message, the first information includes a first offset value and the second timestamp, and the first offset value is a difference between the first timestamp and the estimated timestamp;

[0050] Or, the first information includes a third timestamp, and the third timestamp is the sum of the first offset value and the second timestamp;

[0051] Or, the first information includes a fourth timestamp, a second offset value and the first offset value, the fourth timestamp is an average value of timestamps of the second messages respectively sent by multiple terminals received by the network device, the multiple terminals are terminals in the terminal group to which the first terminal belongs, the second offset value is the difference between the second timestamp and the fourth timestamp, the first terminal belongs to the G terminal groups, and G is a positive integer;

[0052] Or, the first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

[0053] In combination with the second aspect or any one of its implementations, in another possible implementation, the first timestamp is sent by broadcast, and the second timestamp is sent by unicast; or, the first offset value and the second timestamp are sent by unicast; or, the first offset value is sent by broadcast, and the second timestamp is sent by unicast; or, the third timestamp is sent by unicast; or, the fourth timestamp and the first offset value are sent by broadcast, and the second offset value is sent by unicast; or, the fifth timestamp is sent by broadcast, and the second offset value is sent by unicast.

[0054] In a third aspect, the present application provides a communication device, which has the function of implementing the method in the first aspect or any possible implementation thereof, or has the function of implementing the method in the second aspect or any possible implementation thereof. The function can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more units corresponding to the above functions.

[0055] In a fourth aspect, the present application provides a communication device, including a processor, a memory, and a transceiver. The memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory, and control the transceiver to send and receive signals, so that the communication device executes the method in the first aspect or any possible implementation thereof, or executes the method in the second aspect or any possible implementation thereof.

[0056] In a fifth aspect, the present application provides a communication device, comprising a processor and a communication interface, wherein the communication interface is used to receive a signal and transmit the received signal to the processor, and the processor processes the signal so that the method in the first aspect or any possible implementation thereof is executed, or so that the method in the second aspect or any possible implementation thereof is executed.

[0057] Optionally, the communication interface may be an interface circuit, and the processor may be a processing circuit.

[0058] In a sixth aspect, the present application provides a chip comprising a logic circuit and a communication interface, wherein the logic circuit is used to perform the processing as described in the first aspect or any possible implementation thereof, and the communication interface is used to perform the sending and receiving operations as described in the first aspect or any possible implementation thereof.

[0059] Optionally, the communication interface may include an input interface and an output interface.

[0060] In the seventh aspect, the present application provides a chip comprising a logic circuit and a communication interface, wherein the logic circuit is used to perform the processing as described in the second aspect or any possible implementation thereof, and the communication interface is used to perform the sending and receiving operations as described in the second aspect or any possible implementation thereof.

[0061] Optionally, the communication interface may include an input interface and an output interface.

[0062] In an eighth aspect, the present application provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions are run on a computer, the method in the first aspect or any possible implementation thereof is executed, or the method in the second aspect or any possible implementation thereof is executed.

[0063] In a ninth aspect, the present application provides a computer program product, comprising a computer program code, which, when executed on a computer, enables the method in the first aspect or any possible implementation thereof to be executed, or enables the method in the second aspect or any possible implementation thereof to be executed.

[0064] In a tenth aspect, the present application provides a wireless communication system, comprising the communication device described in any one of the above aspects or any possible implementation thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a schematic diagram of an architecture of a communication system to which an embodiment of the present application can be applied.

[0066] Figure 2 It is a schematic diagram of clock synchronization based on PTP.

[0067] Figure 3 It is a schematic flow chart of the clock synchronization method provided in an embodiment of the present application.

[0068] Figure 4 It is a schematic flowchart of a clock synchronization method provided in another embodiment of the present application.

[0069] Figure 5 It is a schematic diagram of the grouping rules.

[0070] Figure 6 It is a schematic diagram for adjusting grouping.

[0071] Figure 7 It is a schematic diagram of the B-IFDMA interleaved structure.

[0072] Figure 8 It is a schematic diagram of a network device indicating a grouping result and time-frequency resources used to transmit a second message.

[0073] Fig. 9 is an example of transmitting the second message.

[0074] Fig.10 It is a schematic diagram of the signal processing flow after grouping.

[0075] Fig.11 It is a schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method.

[0076] Fig.12 This is another schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method.

[0077] Fig.13 This is another schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method.

[0078] Fig.14 This is another schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method.

[0079] Fig.15This is another schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method.

[0080] Fig.16 It is an overall flow chart of the clock synchronization method of an embodiment of the present application.

[0081] Fig.17 It is a schematic block diagram of a communication device provided in an embodiment of the present application.

[0082] Fig.18 It is a schematic block diagram of a communication device provided in another embodiment of the present application.

[0083] Fig.19 A schematic structural diagram of a communication device provided in another embodiment of the present application.

[0084] Fig. 20 A schematic structural diagram of a communication device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0085] In order to facilitate understanding of the embodiments of the present application, the following explanations are made.

[0086] 1. In the embodiments of the present application, "indication" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a certain information is called information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, the information to be indicated may be directly indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated may also be indirectly indicated by indicating other information, wherein the other information has an association with the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, it is also possible to implement the indication of the information to be indicated by means of a pre-agreement (such as a protocol definition) on whether a certain information element exists, thereby reducing the indication overhead to a certain extent.

[0087] 2. In the embodiments shown below, the first, second, third, fourth and various numbers are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application. For example, to distinguish different devices or messages.

[0088] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0089] The technical solution of the embodiment of the present application can be applied to various communication systems, such as: long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD) system, universal mobile telecommunication system (UMTS), world-wide interoperability for microwave access (WiMAX) communication system, fifth generation (5G) communication system, etc. th generation, 5G) system or new radio (newradio, NR), satellite communication system, and future mobile communication system, etc.

[0090] Figure 1 It is a schematic diagram of an architecture of a communication system to which an embodiment of the present application can be applied.

[0091] like Figure 1 As shown, the communication system may include a network device 110 and a terminal 120 (eg Figure 1 The terminal 120 is connected to the network device 110 in a wireless manner. The terminal 120 may be fixed or movable. Figure 1 This is just a schematic diagram. The communication system may also include other network devices, such as wireless relay devices and wireless backhaul devices. Figure 1 The embodiments of the present application do not limit the number of network devices and terminals included in the mobile communication system.

[0092] The terminal in the embodiment of the present application may also be referred to as a slave node, user equipment (UE), user, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal equipment, wireless communication equipment, user agent or user device, etc. The terminal may be a cellular phone, a smart watch, a wireless data card, a mobile phone, a tablet computer, a personal digital assistant (PDA) computer, a wireless modem, a handheld device, a laptop computer, a machine type communication (MTC) terminal, a computer with wireless transceiver function, a virtual reality terminal, an augmented reality terminal, a wireless terminal in industrial control, a wireless terminal in unmanned driving, a wireless terminal in remote surgery, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, a wireless terminal in satellite communication (e.g., satellite phone or satellite terminal, etc.), etc. The embodiment of the present application does not limit the specific technology and specific device form adopted by the terminal.

[0093] The network device in the embodiment of the present application may be a device for communicating with a terminal, and the network device may also be referred to as a master node. The network device may be a base transceiver station (BTS) in a global system of mobile communication (GSM) system or a code division multiple access (CDMA), or a base station (nodeB, NB) in a wideband code division multiple access (WCDMA) system, or an evolutionary base station (eNB or eNodeB) in an LTE system, or a wireless controller in a cloud radio access network (CRAN) scenario, or the network device may be a relay station, an access point, a vehicle-mounted device, or a wearable device, or the network device may be a terminal that performs the function of a base station in D2D communication or machine communication, or the network device may be a network device in a 5G network or a network device in a future evolved PLMN network, etc., and the embodiment of the present application is not limited thereto. In addition, the network device in the embodiment of the present application may also be a module or unit that performs some functions of the base station, for example, it may be a centralized unit (CU) or a distributed unit (DU). The embodiment of the present application does not limit the specific technology and specific device form adopted by the network device.

[0094] The terminal and network device of the embodiment of the present application can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on the water surface; can also be deployed on aircraft, balloons and artificial satellites in the air. The embodiment of the present application does not limit the application scenarios of the network device and the terminal.

[0095] The terminal and the network device of the embodiment of the present application can communicate through unlicensed spectrum. The terminal and the network device can communicate through the spectrum below 6 gigahertz (GHz), can communicate through the spectrum above 6 GHz, and can also communicate using the spectrum below 6 GHz and the spectrum above 6 GHz at the same time. The embodiment of the present application does not limit the spectrum resources used between the terminal and the network device.

[0096] The following describes the technical solution of the embodiment of the present application by taking the industrial wireless communication scenario as an example.

[0097] In factory automation applications, multiple robots work together and require synchronization with an accuracy of 1us. Therefore, clock synchronization of the communication network becomes critical. In traditional communication networks, clock synchronization of the communication network can be achieved based on the precision time protocol (PTP).

[0098] Figure 2 It is a schematic diagram of clock synchronization based on PTP.

[0099] The de facto standard for clock synchronization in wired industrial networks is IEEE 1588 (IEEE Standard for precision clock synchronization protocol for networked measurement and control systems, 2008), also known as the Precision Time Protocol, or PTP. In PTP, the master node synchronizes the clocks of the slave nodes by continuously sending time information.

[0100] Specifically, Figure 2 As shown, the master node shares time with the slave nodes through two-way communication.

[0101] In step 210, the master node sends a synchronization message (sync message) to the slave node at time T1, and the timestamp carried in the synchronization message is an estimated value of T1; the slave node receives the synchronization message sent by the master node at time T2 and records the time.

[0102] In step 220, the master node sends a follow up message to the slave node. The follow up message carries the time when the master node actually sends the synchronization message, that is, the exact time T1. The slave node receives the follow up message and obtains T1.

[0103] In step 230, the slave node sends a delay request message to the master node at time T3, and records T3; the master node receives the delay request message sent by the slave node at time T4.

[0104] In step 240, the master node sends a delay response message to the slave node, and the delay response message carries a timestamp T4; the slave node receives the delay response message sent by the master node and obtains T4.

[0105] Through the above information exchange, the slave node obtains T1, T2, T3, and T4. The slave node can determine the clock offset between the slave node and the master node according to the following formula:

[0106] T2=T1+d ms +θ Formula 1

[0107] T4=T3+d sm -θ Formula 2

[0108]

[0109] Among them, d ms is the transmission delay from the master node to the slave node, d sm is the transmission delay from the node to the master node, θ is the clock offset between the slave node and the master node, T1 is the time when the master node sends the synchronization message, T2 is the time when the slave node receives the synchronization message, T3 is the time when the slave node sends the delay request message, and T4 is the time when the master node receives the delay request message.

[0110] If the transmission delay from the master node to the slave node and the transmission delay from the slave node to the master node are symmetrical (i.e., d ms =d sm ), the calculation of the clock offset is bias-free; otherwise, the calculation of the clock offset is biased.

[0111] Assuming that the transmission delay from the master node to the slave node and the transmission delay from the slave node to the master node are symmetrical, d ms d sm and θ can be calculated using the following formula:

[0112]

[0113]

[0114] It can be seen that PTP needs to exchange timestamps between the master node and the slave node through 4 messages carrying timestamps, so as to achieve clock synchronization between the master node and the slave node.

[0115] In unlicensed bands, communication devices need to perform (listen beforetalk, LBT) to listen to the idle state of the channel before transmitting messages carrying timestamps. In PTP, the need for 4 messages carrying timestamps means that 4 LBTs need to be performed. Due to the uncertain delay caused by LBT, the time interval between the synchronization message and the delay request message may become larger, which may affect the symmetry of the uplink / downlink channels and cause errors in the clock offset estimation. In this way, the more LBTs that need to be performed, the lower the accuracy of the clock offset estimation.

[0116] In response to the above problems, the present application provides a clock synchronization method and apparatus to help improve the accuracy of clock offset estimation.

[0117] Figure 3 It is a schematic flow chart of the clock synchronization method provided in an embodiment of the present application. Figure 3 The method shown may be executed by a terminal and a network device, or may be executed by a module or unit (eg, a chip, a circuit, or a system on chip (SOC), etc.) in the terminal or the network device. Figure 3 The technical solution of the embodiment of the present application is described by taking the execution subject as a terminal and a network device as an example. Figure 3 The illustrated method may include at least some of the following.

[0118] In step 310, the network device sends a first message to the first terminal. Correspondingly, the first terminal receives the first message sent by the network device. The time when the network device sends the first message is T1, and the time when the first terminal receives the first message is T2.

[0119] The embodiment of the present application does not specifically limit the type of the first message, and the first message can be any downlink signal. For example, the first message is Figure 2 The synchronization message shown.

[0120] In step 320, the first terminal sends a second message to the network device. Correspondingly, the network device receives the second message sent by the first terminal. The time when the first terminal sends the second message is T3, and the time when the network device receives the second message is T4.

[0121] Similarly, the embodiment of the present application does not specifically limit the type of the second message, and the second message can be any uplink signal. Figure 2 The delay request message shown.

[0122] In step 330, the network device sends a third message to the first terminal. Correspondingly, the first terminal receives the third message sent by the network device.

[0123] The third message of the embodiment of the present application includes the first information, and the first information is determined according to the first timestamp and the second timestamp. The first timestamp is the above T1, and the second timestamp is the above T4. That is, the third message of the embodiment of the present application carries information that can directly or indirectly indicate the above T1 and T4.

[0124] Similarly, the embodiment of the present application does not specifically limit the type of the third message, and the third message can be any downlink signal. Figure 2 Delayed response message shown.

[0125] In step 340, the first terminal estimates the clock offset between the first terminal and the network device according to the sixth timestamp, the seventh timestamp, and the first information, thereby achieving clock synchronization with the network device. The sixth timestamp is T2, and the seventh timestamp is T3.

[0126] In some implementations, the first terminal may estimate the clock offset between the first terminal and the network device based on the above formula 5.

[0127] The embodiment of the present application does not specifically limit the form of the first information. Specifically, the form of the first information will be described in detail below.

[0128] In the embodiment of the present application, by simultaneously carrying the information that can directly or indirectly indicate the above T1 and T4 in the third message, the timestamp exchange between the network device and the first terminal can be realized through three messages. In this way, the time interval between the first message and the second message can be shortened, and only three LBTs need to be performed, which can reduce the number of LBTs. Therefore, the technical solution of the embodiment of the present application helps to improve the accuracy of clock offset estimation.

[0129] Considering that in some scenarios, there may be multiple terminals that need to maintain accurate clock synchronization with the network device. If each terminal exchanges timestamps with the network device separately, the clock synchronization will take a long time. For this scenario, the embodiment of the present application provides a clock synchronization method that can reduce the time consumption of clock synchronization.

[0130] Figure 4 It is a schematic flowchart of a clock synchronization method provided in another embodiment of the present application. Figure 4 The method shown may be executed by a terminal and a network device, or may be executed by a module or unit (eg, a chip, a circuit, or a system on chip (SOC), etc.) in the terminal or the network device. Figure 4 The technical solution of the embodiment of the present application is described by taking the execution subject as a terminal and a network device as an example. Figure 4 The illustrated method may include at least some of the following.

[0131] In step 410, the network device divides N terminals into G terminal groups, where N is an integer greater than 1, and G is a positive integer less than or equal to N.

[0132] Optionally, the N terminals may be terminals requiring high-precision clock synchronization.

[0133] Optionally, the number G of divided terminal groups may be determined according to the length of the synchronization period or the length of the maximum channel occupancy time (MCOT).

[0134] The embodiment of the present application does not specifically limit the manner in which the network device divides N terminals into G terminal groups.

[0135] In some implementations, the network device divides N terminals into G terminal groups according to at least one of terminal attributes, service priorities, and clock synchronization accuracy requirements. The terminal attributes include terminal moving speed, terminal signal transmission mode, terminal supported standards, terminal supported data rates, and terminal power supply mode.

[0136] Optionally, the network device may determine a grouping standard according to an application scenario, that is, determine which of the terminal attributes, service priorities, and clock synchronization accuracy requirements are used to group the N terminals.

[0137] 1) Grouping criteria is business priority

[0138] For example, in a factory, some terminals (e.g., robots in the factory) collaborate to perform one task, and other terminals (e.g., robots in the factory) collaborate to perform another task. If the terminals that complete the same task are divided into a terminal group, it is beneficial for the terminals to collaborate to perform tasks. In this case, the network device can group the N terminals according to the service type. Furthermore, the network device can group the terminals that perform the most critical tasks (high service priority) into Group 1, and the terminals that perform the least critical tasks (low service priority) into Group G. Terminals in the same group need to maintain clock synchronization with the same level of accuracy and need to be updated at the same synchronization interval.

[0139] 2) Grouping criteria are terminal attributes

[0140] For example, unlicensed frequency bands are mainly used in indoor environments, where some terminals (e.g., robots in factories) move fast, some terminals (e.g., robots in factories) move slowly, and some terminals (e.g., robots in factories) are almost static. In this case, the network device can group N terminals according to terminal attributes, such as the moving speed of the terminal. Further, the network device can group fast-moving terminals into group 1, slow-moving terminals into group 2, and statically moving robots into group G.

[0141] For another example, in Msg2 transmission, some terminals only need to send a reference signal (RS), while other terminals need to send the reference signal together with data (e.g., periodic data traffic). In this case, the network device can group N terminals according to terminal attributes, such as the way in which the terminal sends signals. Specifically, the network device can group terminals that only need to send reference signals into one group, and groups terminals that need to send reference signals and data at the same time into one group.

[0142] 3) Grouping standard is clock synchronization accuracy

[0143] For example, some terminals (e.g., robots in factories) require higher clock synchronization accuracy (e.g., less than 1us), some terminals (e.g., robots in factories) require medium clock synchronization accuracy (e.g., less than 5us), and some terminals (e.g., robots in factories) require lower clock synchronization accuracy (e.g., less than 10us). In this case, the network device can group N terminals according to the clock synchronization accuracy required by the terminals. Furthermore, the network device can group terminals that require higher clock synchronization accuracy into Group 1, terminals that require medium clock synchronization accuracy into Group 2, and terminals that require the lowest clock synchronization accuracy into Group G.

[0144] For another example, some terminals (e.g., robots in factories) have high stability oscillators (e.g., 0.1 ppm), so the synchronization interval can be as long as 300 ms, and some terminals (e.g., robots in factories) have medium stability oscillators (e.g., 0.5 ppm), so the synchronization interval can be as long as 60 ms. In this case, it is beneficial for the network device to group terminals with oscillators of the same stability into the same group.

[0145] 4) Multiple grouping criteria

[0146] For example, the network device can group N terminals by comprehensively considering multiple grouping criteria. For example, based on at least one of terminal attributes, service priority, and clock synchronization accuracy, the network device can group N terminals using an advanced clustering algorithm. The clustering algorithm may include a machine learning clustering algorithm, a neural network clustering algorithm, etc. In this way, the network device can implement multi-dimensional input grouping.

[0147] The embodiments of the present application do not specifically limit the grouping rules.

[0148] In some implementations, it is assumed that each terminal group includes M terminals, that is, each terminal group includes the same number of terminals, N = G*M. Figure 5As shown, first, according to terminal attributes, service priorities or clock synchronization accuracy, N terminals (UE1, UE2, ..., UEk, ..., UEN) are sorted in descending order, and the sorted N terminals are represented as {SUE1, SUE2, ..., SUEk, ..., SUEN}. The sorted N terminals satisfy the following formula:

[0149]

[0150] Among them, λ k is the terminal attribute, service priority or clock synchronization accuracy of the terminal SUEk, i is greater than or equal to 0 and less than or equal to G.

[0151] In some other implementations, it is assumed that the number of terminals included in the G terminal groups may be different, and the g-th terminal group includes Mg terminals, g=1, 2, ..., G, Similarly, first, according to terminal attributes, service priorities or clock synchronization accuracy, N terminals (UE1, UE2, ..., UEk, ..., UEN) are sorted in descending order, and the sorted N terminals are represented as {SUE1, SUE2, ..., SUEk, ..., SUEN}. The sorted N terminals satisfy the following formula:

[0152]

[0153] Among them, λ k is the terminal attribute, service priority or clock synchronization accuracy of the terminal SUEk, i is greater than or equal to 0 and less than or equal to G.

[0154] In some embodiments, the network device may also receive at least one feedback information sent by N terminal devices, the feedback information being used to indicate whether the clock synchronization accuracy of the previous synchronization cycle meets the requirements. When grouping the N terminals, the network device may also consider the feedback information of the terminal devices in addition to the above grouping criteria.

[0155] Some methods for handling abnormal grouping situations are also provided in the embodiments of the present application.

[0156] In some embodiments, after N terminals are divided into G terminal groups, the grouping of some terminals may need to be adjusted. In this case, the grouping of other terminals also needs to be adjusted accordingly, and the remaining terminals still meet the above grouping rules. The situation where the grouping needs to be adjusted may occur in the same synchronization cycle or in different synchronization cycles.

[0157] As an example, due to various reasons, some terminals are not grouped according to the grouping rules described above. In this case, these terminals can be regarded as "queue-jumping" terminals. Due to the influence of the "queue-jumping" terminals, other terminals may need to be adjusted to the next group, and the remaining terminals still follow the above grouping rules. In this way, in terms of clock synchronization accuracy, the above remaining terminals can still benefit from the above grouping rules.

[0158] like Figure 6 As shown, assuming that each terminal group includes the same number of terminals, the grouping of SUE(M+1) is adjusted from Group 2 to Group 1, resulting in SUEM being adjusted from Group 1 to Group 2. In this way, only the grouping of SUE(M+1) and SUEM changes, and the remaining SUE1, SUE2, SUE(M-1), and SUE(M+2)-SUEN still follow the original grouping results.

[0159] As another example, in some cases, some terminals (which may be referred to as "maverick terminals") are not grouped according to the grouping rules described above, but are grouped and updated separately, and accordingly, the grouping of the remaining terminals needs to be adjusted accordingly. For example, these "maverick terminals" may be treated as an independent terminal group, and the remaining terminal groups may be updated accordingly (re-grouping). In this way, in terms of clock synchronization accuracy, except for the "maverick terminals", the remaining terminals can still benefit from the above grouping rules.

[0160] In step 420, the network device indicates the allocated time-frequency resources and grouping results to the N terminals, where the time-frequency resources are used to transmit the second message.

[0161] 1) Different terminal groups occupy different time domain resources

[0162] Terminals in different terminal groups occupy different time domain resources. Allocating time domain resources includes configuring time slot offset, starting OFDM symbol, number of occupied OFDM symbols, etc.

[0163] For different terminal groups, the number of OFDM symbols allocated by the network device may be different. For example, for a terminal group, the terminals included in it only need to send reference signals. In this case, the network device can only allocate 1 OFDM symbol to the terminal group for transmitting the reference signal; for another terminal group, the terminals included in it need to send reference signals and data (for example, periodic data traffic) at the same time. In this case, the network device can allocate 4 OFDM symbols to the terminal group.

[0164] In an embodiment of the present application, the smaller the time interval between the first message and the second message, the better the symmetry of the uplink channel and the downlink channel, which helps to reduce the clock offset estimation error and improve the clock synchronization accuracy. Therefore, for G terminal groups, the network device can first schedule the terminal group with the highest terminal attributes, service priority or clock synchronization accuracy requirements among the G terminal groups to send the second message, and finally schedule the terminal group with the lowest terminal attributes, service priority or clock synchronization accuracy requirements to send the second message. In this way, the time interval between the second message sent by the terminal group with the highest clock synchronization accuracy requirements and the first message is the shortest, which is conducive to achieving high-precision clock synchronization, while the time interval between the second message sent by the terminal group with the lowest clock synchronization accuracy requirements and the first message is the longest, which can achieve lower-precision clock synchronization. In this way, the clock synchronization accuracy requirements of each terminal can be met.

[0165] The above grouping and scheduling process is described below with reference to specific examples.

[0166] Example 1

[0167] Assume that N terminals have similar moving speeds, each terminal has different requirements for clock synchronization accuracy, N=GM, and each terminal group includes M terminals.

[0168] According to the requirements of N terminals for clock synchronization accuracy, N terminals are grouped and γ k It represents the clock synchronization accuracy requirement for the sorted terminal SUEk (i.e., the kth terminal), k = 1, 2, ..., N, then the sorted N terminals meet:

[0169] γ1≥γ2≥...≥γ k ≥γ N Formula 8

[0170] Then connect UE1 to UE M Grouped into Group 1, UE M+1 To UE 2M The group is Group 2, UE (G-1)M+1 To UE GM The group is Group G.

[0171] The first group of terminals with the highest scheduling clock synchronization accuracy requirement of the network device sends the second message first, and the Gth group of terminals with the lowest scheduling clock synchronization accuracy requirement sends the second message last.

[0172] For the first group of terminals, the channel change between the uplink and downlink is the smallest between the transmission of the first message and the second message, and the asymmetry between the uplink transmission delay and the downlink transmission delay is the smallest. Therefore, the first group of terminals can achieve the best performance in terms of clock synchronization accuracy. Similarly, for the G group of terminals, the channel change between the uplink and downlink is the largest, and the asymmetry between the uplink transmission delay and the downlink transmission delay is the largest. Therefore, the performance of the G group of terminals in terms of clock synchronization accuracy is the worst. The above grouping and scheduling scheme can ensure that the terminals with high requirements for clock synchronization accuracy can achieve the highest clock synchronization accuracy.

[0173] Example 2

[0174] Assume that N terminals have different moving speeds, N=GM, and each terminal group includes M terminals.

[0175] According to the moving speed of N terminals, N terminals are grouped and the v k represents the moving speed of the sorted terminal SUEk (i.e., the kth terminal), k = 1, 2, ..., N, then the sorted N terminals satisfy:

[0176] v1≥v2≥...≥v k ≥v N Formula 9

[0177] Then connect UE1 to UE M Grouped into Group 1, UE M+1 To UE 2M The group is Group 2, UE (G-1)M+1 To UE GM The group is Group G.

[0178] The network device schedules the first group of terminals with the fastest moving speed to send the second message first, and schedules the Gth group of terminals with the slowest moving speed to send the second message last.

[0179] By adopting the above grouping and scheduling scheme, the channel change experienced by the first group of terminals when receiving the first message and sending the second message can be minimized. By adopting the above grouping and scheduling scheme, the overall time interval between the first downlink message and the second uplink message can be minimized, thereby minimizing the overall impact of the channel change, thereby minimizing the asymmetry of the uplink transmission delay and the downlink transmission delay.

[0180] 2) Terminals belonging to the same terminal group occupy the same time domain resources and different frequency domain resources

[0181] Terminals belonging to the same terminal group need to send the second message at the same time, so different frequency domain resources need to be allocated to different terminals.

[0182] In some implementations, for unlicensed frequency bands, a block interleave frequency domain multiple access (B-IFDMA) structure will be used for uplink transmission. Figure 7 It is a schematic diagram of the B-IFDMA interleaving structure. Terminals belonging to the same terminal group will be allocated different interleaved frequency resource blocks (i.e., interlaces), and the number of interlaces allocated to different terminals may be different, where an interlace includes one or more subcarriers (SC). For example, a terminal can occupy one interlace, while other terminals in the same group can occupy two interlaces. The network device can allocate an interlace that matches its channel to the terminal based on the channel state information (CSI) and / or channel estimation history fed back by the terminal.

[0183] In the embodiment of the present application, the time domain resources and frequency domain resources allocated by the network device to the N terminals may change from one synchronization period to another. Optionally, the network device may allocate time domain resources and frequency domain resources to the N terminals according to the network environment and / or feedback information from the terminals.

[0184] The grouping result and the indication method of the time-frequency resources used to transmit the second message are described below.

[0185] In some implementations, the network device may indicate the grouping results and time-frequency resources to N terminals in a unicast manner.

[0186] In some other implementations, the network device may indicate the grouping results and time-frequency resources to the N terminals by combining broadcast and unicast.

[0187] As an example, the network device may indicate the following to N terminals:

[0188] a) Number of groups G;

[0189] b) a g-th group of time domain resources for transmitting a second message, g=1, 2, ..., G;

[0190] c) group number g and offset k of the nth terminal in the gth group, n=1, 2, ..., N;

[0191] d) frequency domain resources used by the nth terminal to transmit the second message.

[0192] The group number G and the time domain resources of the g-th group for transmitting the second message can be sent by broadcasting, and the group number g, the offset k of the n-th terminal in the g-th group and the frequency domain resources of the n-th terminal for transmitting the second message can be sent by unicasting. Specifically, Figure 8 shown.

[0193] The signaling overhead between the network device and the N terminal can be reduced by combining broadcast and unicast.

[0194] Optionally, for the time domain resources of the gth group used to transmit the second message, the network device may indicate the allocated time domain resources by broadcasting a resource allocation index. The terminal may determine the time domain resources used to transmit the second message by looking up the table according to the received resource allocation index. Table 1 shows a possible form of a resource configuration table, which may be configured by RRC signaling.

[0195] Table 1

[0196] index Slot offset Starting OFDM symbol The number of occupied OFDM symbols 0 0 2 1 1 0 6 1 2 1 3 2 … … … …

[0197] In step 430, the network device sends a first message to N terminals. Correspondingly, the N terminals receive the first message sent by the network device. The time when the network device sends the first message is T1, and the time when the N terminals receive the first message is T2.

[0198] The embodiment of the present application does not specifically limit the type of the first message, and the first message can be any downlink signal. For example, the first message is Figure 2 The synchronization message shown.

[0199] In step 440, the N terminals respectively send second messages to the network device. Correspondingly, the network device receives the second messages sent by the N terminals.

[0200] Specifically, in step 440-1, the terminals of group 1 first send the second message, and the time when the k-th terminal of group 1 sends the second message is recorded as T3(1, k). Accordingly, the time when the network device receives the second message sent by the terminals of group 1 is recorded as T4(1, k). In step 440-2, the terminals of group 2 then send the second message, and the time when the k-th terminal of group 2 sends the second message is recorded as T3(2, k). Accordingly, the time when the network device receives the second message sent by the terminals of group 2 is recorded as T4(2, k). By analogy, in step 440-G, the terminals of group G send the second message last, and the time when the k-th terminal of group G sends the second message is recorded as T3(G, k). Accordingly, the time when the network device receives the second message sent by the terminals of group G is recorded as T4(G, k).

[0201] In this way, the time interval between the second message and the first message sent by the terminal in group 1 is the shortest, which is conducive to achieving high-precision clock synchronization, while the time interval between the second message and the first message sent by the terminal in group G is the longest, which can achieve low-precision clock synchronization. In this way, the clock synchronization accuracy requirements of each terminal can be met.

[0202] Similarly, the embodiment of the present application does not specifically limit the type of the second message, and the second message can be any uplink signal. Figure 2 The delay request message shown.

[0203] Fig. 9 is an example of transmitting the second message.

[0204] For the transmission of the second message, some terminals only need to transmit a reference signal (RS), while other terminals need to transmit RS together with data. In this case, the terminals that only transmit RS can be grouped into one group, and the terminals that need to transmit RS and data can be grouped into another group. Since the terminals that only transmit RS take a shorter time, while the terminals that transmit RS and data take a longer time, the group of terminals that only transmit RS can be grouped into Group 1, and the terminals that need to transmit RS and data can be grouped into Group 2. Figure 7 As shown, assuming that the bandwidth is 20 MHz, the entire bandwidth is divided into 10 interlaces, each interlace includes 10 resource blocks (RBs), each RB consists of 12 subcarriers, and the spacing between adjacent RBs in the same interlace is 120 subcarriers. Each terminal is allocated 1 interlace, then a maximum of 10 terminals can transmit the second message simultaneously. If the number of terminals included in each terminal is the same, M=10.

[0205] Fig. 9 Take N=20, M=10, G=2 as an example. Fig. 9 As shown, after executing Cat.4LBT, the network device sends a first message to 20 terminals. The first message may carry a downlink demodulation reference signal (DMRS) and a coarse T1 (for example, with an accuracy of 10ms). In the unlicensed frequency band, according to the MCOT sharing mechanism, within the MCOT initiated after the network device executes Cat.4LBT, the terminal may execute 25us LBT. In this way, after receiving the first message, the 20 terminals firstly execute 25us LBT of the 10 terminals in the first group, and send a reference signal to the network device after executing LBT, and then the terminals in the second group execute 25us LBT, and send a reference signal and L bits of data to the network device after executing LBT.

[0206] In step 450, the network device sends a third message to the N terminals respectively. Accordingly, the N terminals receive the third message sent by the network device. The third message includes the first information, and the first information is determined according to the first timestamp and the second timestamp. The first timestamp is the above T1, and the second timestamp is the above T4. It can be understood that for terminals in different groups, T4 may be different. For example, the T4 corresponding to the terminals in the first group is the above T4 (1, k), the T4 corresponding to the terminals in the second group is the above T4 (2, k), and the T4 corresponding to the terminals in the Gth group is the above T4 (G, k).

[0207] Similarly, the embodiment of the present application does not specifically limit the type of the third message, and the third message can be any downlink signal. Figure 2 Delayed response message shown.

[0208] The third message in this embodiment of the present application carries information that may directly or indirectly indicate the above-mentioned T1 and T4.

[0209] After receiving the third message, the N terminals may perform clock synchronization according to the above T2, T3 and the first information.

[0210] It should be noted that Figure 3 The first terminal in can be Figure 4 Any one of the N terminals.

[0211] The following describes in detail the signal processing flow after grouping with reference to specific examples.

[0212] Example 1

[0213] Assume that there are N terminals and they are divided into G terminal groups. The g-th terminal group includes M g terminals, g = 1, 2, ..., G,

[0214] Fig.10 It is a schematic diagram of the signal processing flow after grouping. Fig.11 It is a schematic diagram of the information contained in Msg1, Msg2 and Msg3 and the transmission method. Fig.10 and Fig.11 The Msg1 in the message may correspond to the first message above, the Msg2 may correspond to the second message above, and the Msg3 may correspond to the third message above.

[0215] 1) Transmission of Msg1

[0216] Before transmitting Msg1, the network device can perform Cat.4LBT to sense the availability of the channel. If it is detected that the channel is idle, the length of time the network device occupies the channel can be MCOT. The network device can also transmit a physical downlink control channel (PDCCH) to N terminals. The PDCCH can indicate the grouping result of each terminal and the time-frequency resources (e.g., UL grant) used to transmit Msg2. For the g-th group. The network device can specify a unified starting OFDM symbol and the number of occupied OFDM symbols for the g-th group of terminals, and can specify different frequency resources for each terminal in the g-th group, for example, different interlaces.

[0217] After the above PDCCH transmission, the network device sends Msg1 (for example, synchronization message) to N terminals at time T1. Msg1 may include the estimated time T1' (accuracy is 10ms) when the network device sends Msg1. When the k-th terminal of the g-th group receives Msg1, the terminal records the time T2(g, k) when Msg1 is received, where g = 1, 2, ... G, k = 1, 2, ..., M g .

[0218] Since the precision of T1' is 10 ms, it can be represented by 40 bits, so the effective load of Msg1 is 40 bits.

[0219] 2) Transmission of Msg2

[0220] Before sending Msg2 on the pre-allocated time-frequency resources, the terminal needs to detect channel availability by performing 25us LBT. If the channel is detected to be available, the terminals of the G terminal groups send Msg2 to the network device in turn.

[0221] The order of sending Msg2 is: the first group of terminals sends Msg2 first, then the second group of terminals sends Msg2, and finally, the G group of terminals sends Msg2. The terminals in each terminal group send Msg2 at the same time. The k-th terminal in the g-th group records the actual time T3(g, k) when it sends Msg2. When receiving the Msg2 sent by the k-th terminal in the g-th group, the network device will record the time T4(g, k) when the Msg2 is received.

[0222] In this example, Msg2 may include only a reference signal, such as an RS or a DMRS.

[0223] 3) Transmission of Msg3

[0224] Before transmitting Msg3, the network device can perform Cat.4 LBT to sense the availability of the channel. After LBT is successful, the network device can first transmit PDCCH, which is used to indicate the time and frequency resources for receiving Msg3 to N terminals.

[0225] After transmitting the PDCCH, the network device sends Msg3 to the N terminals. In this example, Msg3 may include T4(g, k) and ΔT, where ΔT is the difference between T1 and T1'.

[0226] Optionally, the precision of T4(g, k) and ΔT are both 10 ns. T4(g, k) may occupy 60 bits, and ΔT may occupy 20 bits, so that the effective load for each terminal is 80 bits, and Msg3 includes N*80 bits.

[0227] Alternatively, if Fig.11 As shown, ΔT and T4(g, k) can be sent in a unicast manner.

[0228] Alternatively, if Fig.12 As shown, ΔT can be sent in a broadcast manner, and T4(g, k) can be sent in a unicast manner.

[0229] 4) Timestamp processing

[0230] After completing the timestamp exchange process, the terminal can determine the clock offset between it and the network device according to the following formula:

[0231]

[0232] Among them, d ms (g, k) is the transmission delay from the network device to the kth terminal of the gth group, d sm (g, k) is the transmission delay from the kth terminal of the gth group to the network device, θ(g, k) is the clock offset between the network device and the kth terminal of the gth group, g = 1, 2, ..., G, k = 1, 2, ..., M g .

[0233] Assumption d ms (g, k) = d sm (g, k), θ(g, k) satisfies the following formula:

[0234]

[0235] Example 2

[0236] In Example 2, the transmission of Msg1 and Msg2 is the same or similar to that in Example 1. Please refer to the relevant description in the example, and no further details will be given here.

[0237] 1) Transmission of Msg3

[0238] Before transmitting Msg3, the network device can perform Cat.4 LBT to sense the availability of the channel. After LBT is successful, the network device can first transmit PDCCH, which is used to indicate the time and frequency resources for receiving Msg3 to N terminals.

[0239] After transmitting the PDCCH, the network device sends Msg3 to N terminals. Fig.13 As shown, Msg3 may include T c (g, k). Where T c (g, k)=T4(g, k)+ΔT, ΔT is the difference between T1 and T1'.

[0240] Optionally, T c The accuracy of (g, k) is 10ns. c (g, k) can occupy 60 bits, so the effective load for each terminal is 60 bits, and Msg3 includes N*60 bits.

[0241] Optionally, T c (g, k) can be sent via unicast.

[0242] 2) Timestamp processing

[0243] After completing the timestamp exchange process, the terminal can determine the clock offset θ(g,k) between itself and the network device according to the following formula:

[0244]

[0245] Example 3

[0246] In Example 3, the transmission of Msg1 and Msg2 is the same or similar to that in Example 1. Please refer to the relevant description in the example, and no further details will be given here.

[0247] 1) Transmission of Msg3

[0248] Before transmitting Msg3, the network device can perform Cat.4 LBT to sense the availability of the channel. After LBT is successful, the network device can first transmit PDCCH, which is used to indicate the time and frequency resources for receiving Msg3 to N terminals.

[0249] After transmitting the PDCCH, the network device sends Msg3 to N terminals. Fig.14 As shown, Msg3 may include T 4_average (g), ΔT and ΔT4(g, k). Among them, T 4_average(g) is the average value of the time when the network device receives Msg2 sent by the g-th group of terminals, ΔT is the difference between T1 and T1', and ΔT4(g, k) is the difference between T4(g, k) and T 4_average (g) The difference between 4_average (g) and ΔT4(g, k) satisfy the following formula:

[0250]

[0251] Optionally, T 4_average The accuracy of ΔT and ΔT4(g, k) is 10ns. ΔT4(g, k) can occupy 10 bits, T 4_average (g) can occupy 60 bits and ΔT can occupy 20 bits, so the total effective load of Msg3 is (G*60+N*10+20) bits.

[0252] Optionally, T 4_average (g) and ΔT may be sent via broadcast, and ΔT4(g, k) may be sent via unicast.

[0253] 2) Timestamp processing

[0254] After completing the timestamp exchange process, the terminal can determine the clock offset θ(g,k) between itself and the network device according to the following formula:

[0255]

[0256] Example 4

[0257] In Example 4, the transmission of Msg1 and Msg2 is the same or similar to that in Example 1. Please refer to the relevant description in the example, and no further details will be given here.

[0258] 1) Transmission of Msg3

[0259] Before transmitting Msg3, the network device can perform Cat.4 LBT to sense the availability of the channel. After LBT is successful, the network device can first transmit PDCCH, which is used to indicate the time and frequency resources for receiving Msg3 to N terminals.

[0260] After transmitting the PDCCH, the network device sends Msg3 to N terminals. Fig.15 As shown, Msg3 may include T c_average (g) and ΔT4(g, k). Where, T c_average (g) = T 4_average (g)+ΔT,T 4_average(g) is the average value of the time when the network device receives Msg2 sent by the g-th group of terminals, ΔT is the difference between T1 and T1', and ΔT4(g, k) is the difference between T4(g, k) and T 4_average (g) The difference between 4_average (g) and ΔT4(g, k) satisfy the following formula 13.

[0261] Optionally, T c_average The accuracy of ΔT4(g, k) and ΔT4(g, k) is 10ns. ΔT4(g, k) can occupy 10 bits, T c_average (g) can occupy 60 bits, so the total payload of Msg3 is (G*60+N*10) bits.

[0262] Optionally, T c_average (g) can be sent via broadcast, and ΔT4(g, k) can be sent via unicast.

[0263] 2) Timestamp processing

[0264] After completing the timestamp exchange process, the terminal can determine the clock offset θ(g,k) between itself and the network device according to the following formula:

[0265]

[0266] In the embodiment of the present application, the information included in Msg3 may also be in other forms or other precisions, which are not specifically limited. For example, Msg3 may include T4(g, k) and T1. The embodiment of the present application also does not specifically limit the transmission mode of Msg3, which may be unicast, broadcast, or a combination of unicast and broadcast.

[0267] Next, combine Fig.16 , the clock synchronization method of the embodiment of the present application is described as a whole. Fig.16 As shown, the network device first divides N terminals into G terminal groups according to the basic information of the terminal, the grouping standards, grouping rules and exception handling rules in different scenarios (corresponding to the content of the grouping adjustment above); then the network device indicates the grouping results and the time-frequency resources used to transmit the second message to the N terminals; then the network device and the N terminals exchange timestamps through the first message, the second message and the third message, and the details can be found in the relevant description above; after exchanging timestamps with the network device, the terminal processes the timestamp to obtain the clock offset between the network device and the terminal. Optionally, the terminal can feedback the grouping requirements and resource allocation requirements of the next synchronization cycle to the network device so that the network device can better group and allocate time-frequency resources.

[0268] The clock synchronization method provided by the present application is described in detail above. The communication device provided by the present application is introduced below.

[0269] It is understandable that in order to implement the functions in the above embodiments, the communication device includes hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0270] Fig.17 1700 is a schematic block diagram of a communication device provided in an embodiment of the present application. The device 1700 has various functional modules for implementing the methods executed by the network device in the above-mentioned method embodiments. Specifically, the device 1700 includes a sending unit 1710 and a receiving unit 1720.

[0271] The sending unit 1710 is configured to send a first message to a first terminal;

[0272] The receiving unit 1720 is configured to receive a second message sent by the first terminal;

[0273] The sending unit 1710 is also used to send a third message to the first terminal, where the third message includes first information, where the first information is determined based on a first timestamp and a second timestamp, where the first timestamp indicates the moment when the network device sends the first message, and the second timestamp indicates the moment when the network device receives the second message.

[0274] Optionally, the sending unit 1710 is also used to send second information to the first terminal, the second information being used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resources corresponding to the terminal belonging to the same terminal group as the first terminal are the first time domain resources, and the frequency domain resources corresponding to the terminal belonging to the same terminal group as the first terminal are different from the first frequency domain resources.

[0275] Optionally, the apparatus 1700 further includes a processing unit 1730, configured for the network device to divide N terminals into G terminal groups, where the N terminals include the first terminal, N is an integer greater than 1, and G is a positive integer less than N.

[0276] Optionally, the processing unit 1730 is specifically configured to divide the N terminals into the G terminal groups according to at least one of service priority, terminal attributes and clock synchronization accuracy requirements.

[0277] Optionally, the processing unit 1730 is specifically used for the network device to divide the N terminals into the G terminal groups according to at least one of the service priority, terminal attributes and clock synchronization accuracy requirements, and at least one feedback information from the N terminals, and the feedback information is used to indicate whether the clock synchronization accuracy of the previous synchronization cycle meets the requirements.

[0278] Optionally, when the service priority of the first terminal group is higher than the service priority of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two of the G terminal groups; and / or, when the clock synchronization accuracy requirement of the first terminal group is higher than the clock synchronization requirement of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two of the G terminal groups.

[0279] Optionally, the second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent via broadcast, and the frequency domain resource allocation information is sent via unicast.

[0280] Optionally, the sending unit 1710 is further used to send third information to the first terminal, where the third information is used to indicate the terminal group to which the first terminal belongs.

[0281] Optionally, the third information includes the group number G, the group number of the terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate the position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

[0282] Optionally, the first information includes the first timestamp and the second timestamp; or, when the first message includes an estimated timestamp of the network device sending the first message, the first information includes a first offset value and the second timestamp, and the first offset value is the difference between the first timestamp and the estimated timestamp; or, the first information includes a third timestamp, and the third timestamp is the sum of the first offset value and the second timestamp; or, the first information includes a fourth timestamp, a second offset value and the first offset value, and the fourth timestamp is the average timestamp of the second messages sent by multiple terminals respectively received by the network device, and the multiple terminals are terminals in the terminal group to which the first terminal belongs, and the second offset value is the difference between the second timestamp and the fourth timestamp; or, the first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

[0283] Optionally, the first timestamp is sent by broadcast, and the second timestamp is sent by unicast; or, the first offset value and the second timestamp are sent by unicast; or, the first offset value is sent by broadcast, and the second timestamp is sent by unicast; or, the third timestamp is sent by unicast; or, the fourth timestamp and the first offset value are sent by broadcast, and the second offset value is sent by unicast; or, the fifth timestamp is sent by broadcast, and the second offset value is sent by unicast.

[0284] In the above implementations, the sending unit 1710 may be implemented by a transmitter, the receiving unit 1720 may be implemented by a receiver, and the processing unit 1730 may be implemented by a processor.

[0285] Optionally, the transmitter and the receiver may be provided separately, or may be part of a transceiver having receiving and transmitting functions, which is not limited here.

[0286] Optionally, as an example, the communication device 1700 may be a network device in the method embodiment.

[0287] Alternatively, as another example, the communication device 1700 may be a chip or integrated circuit installed in a network device. In this case, the sending unit 1710 and the receiving unit 1720 may be communication interfaces or interface circuits. For example, the sending unit 1710 is an output interface or output circuit, and the receiving unit 1720 is an input interface or input circuit.

[0288] In various examples, the processing unit 1730 is used to perform processes and / or operations implemented internally by the communication device in addition to the actions of sending and receiving.

[0289] Optionally, the processing unit 1730 may be a processing device. The functions of the processing device may be implemented by hardware, or by hardware executing corresponding software. For example, the processing device may include at least one processor and at least one memory, wherein the at least one memory is used to store a computer program, and the at least one processor reads and executes the computer program stored in the at least one memory, so that the communication device 1700 performs the operations and / or processing performed by the network device in each method embodiment.

[0290] Alternatively, the processing device may only include a processor, and a memory for storing the computer program is located outside the processing device. The processor is connected to the memory through circuits / wires to read and execute the computer program stored in the memory.

[0291] In some examples, the processing device may also be a chip or an integrated circuit. For example, the processing device includes a processing circuit / logic circuit and an interface circuit, wherein the interface circuit is used to perform the sending and receiving operations performed by the network device in each method embodiment, and the processing circuit / logic circuit is used to perform the packet processing performed by the network device in each method embodiment.

[0292] For a more detailed description of the sending unit 1710, the receiving unit 1720 and the processing unit 1730, reference may be made to the relevant descriptions in the above method embodiments, which will not be repeated here.

[0293] Fig.18 1800 is a schematic block diagram of a communication device provided by another embodiment of the present application. The device 1800 has various functional modules for implementing the methods executed by the terminal in the above-mentioned method embodiments. Specifically, the device 1800 includes a sending unit 1810, a receiving unit 1820 and a processing unit 1830.

[0294] The receiving unit 1820 is configured to receive a first message sent by a network device;

[0295] The sending unit 1810 is configured to send a second message to the network device;

[0296] The receiving unit 1820 is further configured to receive a third message sent by the network device, where the third message includes first information, where the first information is determined according to a first timestamp and a second timestamp, where the first timestamp indicates a time when the network device sends the first message, and the second timestamp indicates a time when the network device receives the second message;

[0297] Processing unit 1830 is used to perform clock synchronization with the network device according to a sixth timestamp, a seventh timestamp and the first information, the sixth timestamp indicating the moment when the first terminal receives the first message, and the seventh timestamp indicating the moment when the first terminal sends the second message.

[0298] Optionally, the receiving unit 1820 is also used to receive second information sent by the network device, the second information being used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resource corresponding to a terminal belonging to the same terminal group as the first terminal is the first time domain resource, and the frequency domain resource corresponding to a terminal belonging to the same terminal group as the first terminal is different from the first frequency domain resource.

[0299] Optionally, the second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent via broadcast, and the frequency domain resource allocation information is sent via unicast.

[0300] Optionally, the receiving unit 1820 is further used to receive third information sent by the network device, where the third information is used to indicate the terminal group to which the first terminal belongs.

[0301] Optionally, the third information includes the group number G, the group number of the terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate the position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

[0302] Optionally, the first information includes the first timestamp and the second timestamp; or, when the first message includes an estimated timestamp when the network device sends the first message, the first information includes a first offset value and the second timestamp, and the first offset value is the difference between the first timestamp and the estimated timestamp; or, the first information includes a third timestamp, and the third timestamp is the sum of the first offset value and the second timestamp; or, the first information includes a fourth timestamp, a second offset value and the first offset value, and the fourth timestamp is the average value of the timestamps of the second messages sent by multiple terminals respectively received by the network device, and the multiple terminals are terminals in the terminal group to which the first terminal belongs, and the second offset value is the difference between the second timestamp and the fourth timestamp, and the first terminal belongs to the G terminal groups, and G is a positive integer; or, the first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

[0303] Optionally, the first timestamp is sent by broadcast, and the second timestamp is sent by unicast; or, the first offset value and the second timestamp are sent by unicast; or, the first offset value is sent by broadcast, and the second timestamp is sent by unicast; or, the third timestamp is sent by unicast; or, the fourth timestamp and the first offset value are sent by broadcast, and the second offset value is sent by unicast; or, the fifth timestamp is sent by broadcast, and the second offset value is sent by unicast.

[0304] In the above implementations, the sending unit 1810 may be implemented by a transmitter, the receiving unit 1820 may be implemented by a receiver, and the processing unit 1830 may be implemented by a processor.

[0305] Optionally, the transmitter and the receiver may be provided separately, or may be part of a transceiver having receiving and transmitting functions, which is not limited here.

[0306] Optionally, as an example, the communication device 1800 may be a terminal in a method embodiment.

[0307] Alternatively, as another example, the communication device 1800 may be a chip or integrated circuit installed in a terminal. In this case, the sending unit 1810 and the receiving unit 1820 may be communication interfaces or interface circuits. For example, the sending unit 1810 is an output interface or output circuit, and the receiving unit 1820 is an input interface or input circuit.

[0308] In various examples, the processing unit 1830 is used to perform processes and / or operations implemented internally by the communication device in addition to the actions of sending and receiving.

[0309] Optionally, the processing unit 1830 may be a processing device. The functions of the processing device may be implemented by hardware, or by hardware executing corresponding software. For example, the processing device may include at least one processor and at least one memory, wherein the at least one memory is used to store a computer program, and the at least one processor reads and executes the computer program stored in the at least one memory, so that the communication device 1800 performs the operations and / or processing performed by the network device in each method embodiment.

[0310] Alternatively, the processing device may only include a processor, and a memory for storing the computer program is located outside the processing device. The processor is connected to the memory through circuits / wires to read and execute the computer program stored in the memory.

[0311] In some examples, the processing device may also be a chip or an integrated circuit. For example, the processing device includes a processing circuit / logic circuit and an interface circuit, wherein the interface circuit is used to perform the sending and receiving operations performed by the terminal in each method embodiment, and the processing circuit / logic circuit is used to perform the packet processing performed by the terminal in each method embodiment.

[0312] For a more detailed description of the sending unit 1810, the receiving unit 1820 and the processing unit 1830, reference may be made to the relevant descriptions in the above-mentioned method embodiments, which will not be repeated here.

[0313] Fig.19 This is a schematic structural diagram of a communication device provided in another embodiment of the present application. Fig.19 As shown, the device 1900 includes one or more processors 1910 and one or more interface circuits 1920. The processor 1910 and the interface circuit 1920 are coupled to each other. It is understood that the interface circuit 1920 can be a transceiver or an input-output interface. Optionally, the device 1900 may also include one or more memories 1930 for storing instructions executed by the processor 1910 or storing input data required by the processor 1910 to execute instructions or storing data generated after the processor 1910 executes instructions.

[0314] When the apparatus 1900 is used to implement the functions of the network device in the above-mentioned method embodiments, the processor 1910 is used to execute the functions of the above-mentioned processing unit 1730 , and the interface circuit 1920 is used to execute the functions of the above-mentioned sending unit 1710 and the receiving unit 1720 .

[0315] In one implementation, the apparatus 1900 may be a network device in a method embodiment.

[0316] Fig. 20 This is a schematic structural diagram of a communication device provided in another embodiment of the present application. Fig. 20 As shown, the device 2000 includes one or more processors 2010 and one or more interface circuits 2020. The processor 2010 and the interface circuit 2020 are coupled to each other. It is understood that the interface circuit 2020 can be a transceiver or an input-output interface. Optionally, the device 2000 may also include one or more memories 2030 for storing instructions executed by the processor 2010 or storing input data required by the processor 2010 to execute instructions or storing data generated after the processor 2010 executes instructions.

[0317] When the device 2000 is used to implement the functions of the terminal in the above-mentioned method embodiments, the processor 2010 is used to execute the functions of the above-mentioned processing unit 1830, and the interface circuit 2020 is used to execute the functions of the above-mentioned sending unit 1810 and the receiving unit 1820.

[0318] In one implementation, the apparatus 2000 may be a terminal in a method embodiment.

[0319] Optionally, the memory and processor in the above-mentioned device embodiments may be physically independent units, or the memory may be integrated with the processor, which is not limited in this document.

[0320] In addition, the present application also provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions are executed on a computer, the operations and / or processes performed by the network device in each method embodiment of the present application are executed.

[0321] The present application also provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions are executed on a computer, the operations and / or processes performed by the terminal in the various method embodiments of the present application are executed.

[0322] In addition, the present application also provides a computer program product, which includes computer program code or instructions. When the computer program code or instructions are run on a computer, the operations and / or processes performed by the network device in the various method embodiments of the present application are executed.

[0323] The present application also provides a computer program product, which includes computer program code or instructions. When the computer program code or instructions are run on a computer, the operations and / or processes performed by the terminal in the various method embodiments of the present application are executed.

[0324] In addition, the present application also provides a chip, which includes a processor, a memory for storing computer programs is set independently of the chip, and the processor is used to execute the computer program stored in the memory, so that a network device equipped with the chip performs the operations and / or processing performed by the network device in any one of the method embodiments.

[0325] Furthermore, the chip may further include a communication interface. The communication interface may be an input / output interface, or an interface circuit, etc. Furthermore, the chip may further include the memory.

[0326] The present application also provides a chip, which includes a processor, a memory for storing computer programs which is set independently of the chip, and the processor is used to execute the computer program stored in the memory, so that a terminal equipped with the chip executes the operations and / or processing performed by the terminal in any one of the method embodiments.

[0327] Furthermore, the chip may further include a communication interface. The communication interface may be an input / output interface, or an interface circuit, etc. Furthermore, the chip may further include the memory.

[0328] In addition, the present application also provides a communication device (for example, a chip), including a processor and a communication interface, wherein the communication interface is used to receive a signal and transmit the signal to the processor, and the processor processes the signal so that the operations and / or processing performed by the network device in any method embodiment are executed.

[0329] The present application also provides a communication device (for example, a chip), including a processor and a communication interface, wherein the communication interface is used to receive a signal and transmit the signal to the processor, and the processor processes the signal so that the operations and / or processing performed by the terminal in any method embodiment are executed.

[0330] In addition, the present application also provides a communication device, comprising at least one processor, wherein the at least one processor is coupled to at least one memory, and the at least one processor is used to execute a computer program or instruction stored in the at least one memory, so that the operations and / or processing performed by the network device in any method embodiment are executed.

[0331] The present application also provides a communication device, comprising at least one processor, wherein the at least one processor is coupled to at least one memory, and the at least one processor is used to execute a computer program or instruction stored in the at least one memory, so that the operations and / or processing performed by the terminal in any method embodiment are executed.

[0332] In addition, the present application also provides a communication device, including a processor, a memory, and a transceiver. The memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory, and control the transceiver to send and receive signals, so that the network device performs the operation and / or processing performed by the network device in any one of the method embodiments.

[0333] The present application also provides a communication device, including a processor, a memory and a transceiver. The memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory, and control the transceiver to send and receive signals, so that the terminal performs the operation and / or processing performed by the terminal in any method embodiment.

[0334] In addition, the present application also provides a wireless communication system, including the network device and terminal in the embodiments of the present application.

[0335] The processor in the embodiment of the present application can be an integrated circuit chip with the ability to process signals. In the implementation process, each step of the above method embodiment can be completed by the hardware integrated logic circuit or software instructions in the processor. The processor can be a general-purpose processor, a digital signal processor (digital signal processor, DSP), an application-specific integrated circuit (application-specific integrated circuit, ASIC), a field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware coding processor to perform, or the hardware and software modules in the coding processor are combined and performed. The software module can be located in a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, and other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0336] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DRRAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0337] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0338] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0339] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0340] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0341] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0342] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Among them, A, B and C can all be singular or plural, without limitation.

[0343] In the embodiments of the present application, the numbers "first" and "second" are used to distinguish the same or similar items with substantially the same functions and effects. Those skilled in the art will understand that "first" and "second" do not limit the quantity and sequence, and "first", "second", etc. do not necessarily limit them to be different.

[0344] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application.

[0345] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A clock synchronization method, characterized in that: include: The network device sends a first message to the first terminal; The network device receives a second message sent by the first terminal; The network device sends a third message to the first terminal, where the third message includes first information, where the first information is determined according to a first timestamp and a second timestamp, where the first timestamp indicates a time when the network device sends the first message, and the second timestamp indicates a time when the network device receives the second message; The method further comprises: The network device sends second information to the first terminal, and the second information is used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is the first time domain resource, and the frequency domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is different from the first frequency domain resource.

2. The method according to claim 1, characterized in that The method further comprises: The network device divides N terminals into G terminal groups, where the N terminals include the first terminal, N is an integer greater than 1, and G is a positive integer less than N.

3. The method according to claim 2, characterized in that The network device divides N terminals into G terminal groups, including: The network device divides the N terminals into the G terminal groups according to at least one of service priority, terminal attributes and clock synchronization accuracy requirements.

4. The method according to claim 3, characterized in that The network device divides the N terminals into the G terminal groups according to at least one of service priority, terminal characteristics, and clock synchronization accuracy requirements, including: The network device divides the N terminals into the G terminal groups according to at least one of service priority, terminal attributes and clock synchronization accuracy requirements, and at least one feedback information from the N terminals, wherein the feedback information is used to indicate whether the clock synchronization accuracy of the previous synchronization cycle meets the requirements.

5. The method according to claim 3 or 4, characterized in that: When the service priority of the first terminal group is higher than the service priority of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two terminal groups among the G terminal groups; and / or, When the clock synchronization accuracy requirement of the first terminal group is higher than that of the second terminal group, the time when the first terminal group sends the second message is earlier than the time when the second terminal group sends the second message, and the first terminal group and the second terminal group are any two terminal groups among the G terminal groups.

6. The method according to claim 3 or 4, characterized in that: The second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent in a broadcasting manner, and the frequency domain resource allocation information is sent in a unicast manner.

7. The method according to claim 3 or 4, characterized in that: The method further comprises: The network device sends third information to the first terminal, where the third information is used to indicate the terminal group to which the first terminal belongs.

8. The method according to claim 7, characterized in that The third information includes the group number G, the group number of the terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate the position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

9. The method according to claim 3 or 4, characterized in that: The first information includes the first timestamp and the second timestamp; or, When the first message includes an estimated timestamp when the network device sends the first message, the first information includes a first offset value and the second timestamp, and the first offset value is a difference between the first timestamp and the estimated timestamp; or, The first information includes a third timestamp, where the third timestamp is the sum of the first offset value and the second timestamp; or, The first information includes a fourth timestamp, a second offset value, and the first offset value, the fourth timestamp being an average of timestamps of the second messages respectively sent by a plurality of terminals received by the network device, the plurality of terminals being terminals in a terminal group to which the first terminal belongs, and the second offset value being a difference between the second timestamp and the fourth timestamp; or, The first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

10. The method according to claim 9, characterized in that The first timestamp is sent in a broadcast manner, and the second timestamp is sent in a unicast manner; or, The first offset value and the second timestamp are sent in a unicast manner; or, The first offset value is sent by broadcasting, and the second timestamp is sent by unicasting; or, The third timestamp is sent in a unicast manner; or, The fourth timestamp and the first offset value are sent by broadcasting, and the second offset value is sent by unicasting; or, The fifth timestamp is sent via broadcast, and the second offset value is sent via unicast.

11. A clock synchronization method, characterized in that: include: The first terminal receives a first message sent by the network device; The first terminal sends a second message to the network device; The first terminal receives a third message sent by the network device, where the third message includes first information, where the first information is determined according to a first timestamp and a second timestamp, where the first timestamp indicates a time when the network device sends the first message, and the second timestamp indicates a time when the network device receives the second message; The first terminal performs clock synchronization with the network device according to a sixth timestamp, a seventh timestamp and the first information, the sixth timestamp indicating a time when the first terminal receives the first message, and the seventh timestamp indicating a time when the first terminal sends the second message; The method further comprises: The first terminal receives second information sent by the network device, the second information is used to indicate a first time domain resource and a first frequency domain resource used to transmit the second message, the time domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is the first time domain resource, and the frequency domain resource corresponding to the terminal belonging to the same terminal group as the first terminal is different from the first frequency domain resource.

12. The method according to claim 11, characterized in that The second information includes time domain resource allocation information and frequency domain resource allocation information, wherein the time domain resource allocation information is sent in a broadcasting manner, and the frequency domain resource allocation information is sent in a unicast manner.

13. The method according to claim 11 or 12, characterized in that: The method further comprises: The first terminal receives third information sent by the network device, where the third information is used to indicate the terminal group to which the first terminal belongs.

14. The method according to claim 13, characterized in that The third information includes the group number G, the group number of the terminal group to which the first terminal belongs, and a third offset value, wherein the third offset value is used to indicate the position of the first terminal in the terminal group to which it belongs, wherein the group number G is sent via broadcast, and the group number and the third offset value are sent via unicast.

15. The method according to claim 11 or 12, characterized in that: The first information includes the first timestamp and the second timestamp; or, When the first message includes an estimated timestamp when the network device sends the first message, the first information includes a first offset value and the second timestamp, and the first offset value is a difference between the first timestamp and the estimated timestamp; or, The first information includes a third timestamp, where the third timestamp is the sum of the first offset value and the second timestamp; or, The first information includes a fourth timestamp, a second offset value, and the first offset value, the fourth timestamp being an average of timestamps of the second messages respectively sent by multiple terminals received by the network device, the multiple terminals being terminals in a terminal group to which the first terminal belongs, the second offset value being a difference between the second timestamp and the fourth timestamp, the first terminal belonging to G terminal groups, and G being a positive integer; or, The first information includes a fifth timestamp and the second offset value, and the fifth timestamp is the sum of the first offset value and the fourth timestamp.

16. The method according to claim 15, characterized in that The first timestamp is sent in a broadcast manner, and the second timestamp is sent in a unicast manner; or, The first offset value and the second timestamp are sent in a unicast manner; or, The first offset value is sent by broadcasting, and the second timestamp is sent by unicasting; or, The third timestamp is sent in a unicast manner; or, The fourth timestamp and the first offset value are sent by broadcasting, and the second offset value is sent by unicasting; or, The fifth timestamp is sent via broadcast, and the second offset value is sent via unicast.

17. A communication device, characterized in that: The method comprises a module or a unit for executing the method according to any one of claims 1 to 16.

18. A communication device, characterized in that: The device comprises at least one processor coupled to at least one memory, and the at least one processor is used to execute a computer program or instruction stored in the at least one memory, so that the communication device executes the method according to any one of claims 1 to 16.

19. A chip, characterized in that: It comprises a logic circuit and a communication interface, wherein the communication interface is used to receive data and / or information to be processed, the logic circuit is used to perform data and / or information processing as described in any one of claims 1 to 16, and the communication interface is also used to output the data and / or information processed by the logic circuit.

20. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions. When the computer instructions are executed on a computer, the method according to any one of claims 1 to 16 is implemented.

21. A computer program product, characterized in that The computer program product comprises a computer program code, and when the computer program code is run on a computer, the method according to any one of claims 1 to 16 is implemented.

22. A wireless communication system, characterized in that: include: A communication device for implementing the method according to any one of claims 1 to 10, and a communication device for implementing the method according to any one of claims 11 to 16.

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