CN111526577A

CN111526577A - Clock synchronization method and equipment

Info

Publication number: CN111526577A
Application number: CN201910106165.XA
Authority: CN
Inventors: 黄曲芳; 范强; 徐小英; 娄崇
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-02-01
Filing date: 2019-02-01
Publication date: 2020-08-11
Also published as: WO2020156343A1

Abstract

The embodiment of the application discloses a clock synchronization method and equipment, relates to the field of communication, and solves the problem that the clock synchronization error between a terminal and network equipment is large. The specific scheme is as follows: the method comprises the steps that a terminal acquires first information, wherein the first information is used for determining transmission delay of the terminal and network equipment; a terminal acquires a first time value, wherein the first time value is used for indicating the sending time of a frame boundary of a wireless frame of a first cell of network equipment; and the terminal determines a second time value corresponding to the receiving time of the frame boundary of the wireless frame of the first cell according to the obtained transmission delay and the first time value.

Description

Clock synchronization method and equipment

Technical Field

The embodiment of the application relates to the field of communication, in particular to a clock synchronization method and device.

Background

In the existing communication system, clock synchronization needs to be realized between nodes communicating with each other. The current clock synchronization mainly comprises the following modes: global Positioning Systems (GPS) 1588. In the GPS mode, each node can obtain accurate time by receiving a signal transmitted from a GPS satellite, so as to achieve clock synchronization. The GPS system requires that a node can directly receive a GPS satellite signal, and a node located indoors cannot directly receive a GPS satellite signal. In the 1588 scheme, a node (for example, referred to as a master node) may be selected within a certain range, a clock on the master node is used as a master clock (master clock), and clocks on other nodes (for example, referred to as slave nodes) are synchronized with the master clock as much as possible, that is, clock synchronization is achieved. The premise of realizing clock synchronization in the 1588 mode is that the transmission delay from the master node to the slave node is the same as the transmission delay from the slave node to the master node. However, the terminal is not necessarily located outdoors, and in addition, the transmission delay from the network device to the terminal is not the same as the transmission delay from the terminal to the network device. Therefore, the terminal is not suitable for performing clock synchronization with the network device using the GPS method or the 1588 method. Therefore, a clock synchronization method and device are needed to solve the problem of clock synchronization between a terminal and a network device.

Disclosure of Invention

In view of this, embodiments of the present application provide a clock synchronization method and device to solve the problem of clock synchronization between a terminal and a network device.

In a first aspect, an embodiment of the present application provides a clock synchronization method, where the method may include: the terminal acquires first information used for determining the transmission delay between the terminal and the first network device, and acquires a first time value indicating the sending time of the frame boundary of the wireless frame of the first cell of the first network device, and the terminal can determine a second time value corresponding to the receiving time of the frame boundary of the wireless frame of the first cell according to the acquired transmission delay and the first time value, so as to complete clock synchronization.

With reference to the first aspect, in a possible implementation manner, the first information may be information used to indicate a transmission delay.

With reference to the first aspect or the foregoing possible implementation manner, in another possible implementation manner, the first information may be information used to indicate a distance between the terminal and the first network device; correspondingly, the method may further include: the terminal may obtain the transmission delay according to a distance between the terminal and the first network device. That is to say, the terminal may obtain the transmission delay between the terminal and the first network device according to the obtained information for indicating the distance. Instead of using the TA to obtain the transmission delay, the transmission delay with the first network device may be obtained without first sending a signal (such as a preamble) to the first network device.

With reference to the first aspect or the foregoing possible implementation manner, in another possible implementation manner, the method may further include: the terminal acquires the moving distance from the moment of acquiring the first information to the current moment; when the moving distance is greater than the distance threshold, it indicates that the transmission delay between the terminal and the first network device may be changed, and the terminal may send, to the first network device, first indication information for indicating the first network device to resend the first information, so that the first network device resends, to the terminal, the first information for determining the transmission delay between the terminal and the first network device.

With reference to the first aspect or the foregoing possible implementation manner, in another possible implementation manner, since the terminal may have an error when performing frame boundary detection of a radio frame, in order to reduce the error as much as possible, the method may further include: a terminal acquires the receiving time of the frame boundaries of the wireless frames of M cells, the frame boundaries of the wireless frames of the M cells are aligned, the M cells comprise a first cell, and M is an integer greater than or equal to 2; and the terminal updates the receiving time of the frame boundary of the wireless frame of the first cell according to the receiving time of the frame boundary of the wireless frame of the M cells. That is, the terminal may detect the frame boundaries of the radio frames of the multiple cells, and then finally determine the frame boundaries of the radio frames according to the detected result.

With reference to the first aspect or the foregoing possible implementation manner, in another possible implementation manner, the acquiring, by the terminal, the first time value may specifically include: the terminal may receive time values indicating the transmission time of frame boundaries of radio frames of M cells, the frame boundaries of the radio frames of the M cells being aligned, the M cells including a first cell, M being an integer greater than or equal to 2, and then determine the first time value according to the obtained time values of the M cells.

With reference to the first aspect or the foregoing possible implementation manner, in another possible implementation manner, under the condition that a sending period of a time service message in each cell is not changed, the first network device may ensure that sending periods of time service messages in each of the multiple cells are staggered, so that the terminal may read the time service messages more frequently. That is, in M cells, the time windows of the terminals receiving the time values indicating the transmission time of the frame boundary of the radio frame are different for different cells; correspondingly, the method may further include: the terminal may receive second indication information from the first network device, where the second indication information may be used to indicate a time window of a time value indicating a transmission time of a frame boundary of a radio frame for a cell received in each of N cells, where the N cells include M cells, and N is an integer greater than or equal to M; the method for receiving, by a terminal, a time value indicating a transmission time of a frame boundary of a radio frame in M cells may specifically include: and the terminal receives the time values of the M cells according to the time window indicated by the second indication information.

With reference to the first aspect or the foregoing possible implementation manners, in another possible implementation manner, in order to enable the first network device to allocate an appropriate number of cells to the terminal, the method may further include: the terminal may send third indication information to the first network device, where the third indication information is used for the first network device to allocate a cell to the terminal, and the cell allocated to the terminal includes M cells; the third indication information is the precision requirement of the terminal on the clock of the terminal; or, the third indication information is an identifier of the first service of the terminal or a QoS identifier of the first service, and the accuracy requirement of the first service of the terminal on the clock of the terminal is greater than the accuracy requirement of other services of the terminal on the clock of the terminal.

With reference to the first aspect or the foregoing possible implementation manners, in another possible implementation manner, the method may further include: the terminal receives a third time value sent by the first network equipment, wherein the third time value is used for indicating the sending time of a subframe boundary of a second cell of the second network equipment; after the terminal is switched to the second cell, acquiring a fourth time value, wherein the fourth time value is used for indicating the receiving time of the subframe boundary of the second cell; the terminal determines the transmission delay between the terminal and the second network equipment according to the third time value and the fourth time value; and the terminal transmits data according to the transmission delay between the terminal and the second network equipment.

With reference to the first aspect or the foregoing possible implementation manners, in another possible implementation manner, the method may further include: after the terminal is switched to a second cell of second network equipment, acquiring a system frame number of the second cell, and receiving a fifth time value sent by the second network equipment, wherein the fifth time value is used for indicating the sending time of a frame boundary of a wireless frame of the second cell; the terminal acquires a sixth time value according to the system frame number, wherein the sixth time value is used for indicating the receiving moment of the frame boundary of the wireless frame of the second cell; the terminal determines the transmission delay between the terminal and the second network equipment according to the fifth time value and the sixth time value; and the terminal transmits data according to the transmission delay between the terminal and the second network equipment.

In a second aspect, an embodiment of the present application provides a clock synchronization method, where the method may include: the first network equipment acquires the distance between the terminal and the first network equipment, generates first information for determining the transmission delay between the terminal and the first network equipment according to the distance, and sends the first information to the terminal.

With reference to the second aspect, in a possible implementation manner, the first network device sends, to the terminal, a time value indicating a sending time of a frame boundary of a radio frame through a cell allocated to the terminal, where the cell allocated to the terminal includes the first cell.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, the first information may be information used for indicating a transmission delay; alternatively, the first information may be information indicating a distance between the terminal and the first network device.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, the method further includes: the method comprises the steps that first network equipment obtains the distance between a terminal and the first network equipment; when the acquired distance between the terminal and the first network device is changed compared with the distance between the terminal and the first network device when the first network device issues the first information, which indicates that the transmission delay between the terminal and the first network device may be changed, the first network device sends the first information to the terminal again.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, the cells allocated to the terminal include N cells, frame boundaries of radio frames of the N cells are aligned, and N is an integer greater than or equal to 2.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, under the condition that a sending period of the time service message in each cell is not changed, the first network device may ensure that sending periods of the time service messages in each of the multiple cells are staggered, so that the terminal may read the time service messages more frequently. The first network device sends, to the terminal through the cell allocated to the terminal, a time value indicating a sending time of a frame boundary of the radio frame, which may specifically include: the first network equipment sends a time value indicating the sending time of a frame boundary of a wireless frame to the terminal through each cell in the N cells in different time windows; the method may further comprise: and the first network equipment sends second indication information to the terminal, wherein the second indication information is used for indicating a time window of a time value of a sending time of a receiving cell indicating a frame boundary of a wireless frame in each cell of the N cells of the terminal.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, in order to allocate an appropriate number of cells to the terminal, the first network device may allocate cells to the terminal according to an instruction of the terminal. Namely, the method may further comprise: the first network equipment receives third indication information from the terminal; the first network equipment acquires the number X of the cells needing to be allocated to the terminal according to the third indication information; the first network equipment allocates N cells for the terminal according to the number X, wherein N is greater than or equal to the number X; wherein: the third indication information is the precision requirement of the terminal on the clock of the terminal, and different precision requirements correspond to different numbers X; or, the third indication information is an identifier of the first service of the terminal, and the identifiers of different services correspond to different numbers X; or, the third indication information is a QoS identifier of the first service, and different QoS identifiers correspond to different numbers X; the accuracy requirement of the first service of the terminal on the clock of the terminal is greater than the accuracy requirement of other services of the terminal on the clock of the terminal.

With reference to the second aspect or the foregoing possible implementation manner, in another possible implementation manner, the method may further include: the first network equipment receives a third time value sent by the second network equipment, wherein the third time value is used for indicating the sending time of a subframe boundary of a second cell of the second network equipment; and the first network equipment sends the third time value to the terminal.

In a third aspect, embodiments of the present application provide a clock synchronization apparatus, which includes a unit or means (means) for performing the steps of the first aspect. Specifically, the method comprises the following steps: the clock synchronization apparatus may include:

a first obtaining unit, configured to obtain first information and a first time value, where the first information is used to determine a transmission delay between a clock synchronization apparatus and a first network device, and the first time value is used to indicate a sending time of a frame boundary of a wireless frame of a first cell of the first network device; and the determining unit is used for determining a second time value corresponding to the receiving time of the frame boundary of the wireless frame of the first cell according to the transmission delay and the first time value.

With reference to the third aspect, in a possible implementation manner, the first information is information used for indicating a transmission delay.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the first information is information used to indicate a distance between the clock synchronization apparatus and the first network device; the first obtaining unit is further configured to obtain the transmission delay according to a distance between the clock synchronization apparatus and the first network device.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a second acquiring unit and a transmitting unit; the second acquisition unit is used for acquiring the moving distance from the moment of acquiring the first information to the current moment of the clock synchronization device; and the sending unit is used for sending first indication information to the first network equipment when the moving distance is greater than the distance threshold, wherein the first indication information is used for indicating the first network equipment to resend the first information.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: an update unit; the first obtaining unit is further configured to obtain a receiving time of a frame boundary of a radio frame of M cells, the frame boundaries of the radio frame of M cells are aligned, the M cells include a first cell, and M is an integer greater than or equal to 2; and the updating unit is used for updating the receiving time of the frame boundary of the wireless frame of the first cell according to the receiving time of the frame boundary of the wireless frame of the M cells.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a receiving unit; a receiving unit, configured to receive time values indicating transmission timings of frame boundaries of radio frames of M cells, the frame boundaries of the radio frames of the M cells being aligned, the M cells including a first cell, M being an integer greater than or equal to 2; the first obtaining unit is specifically configured to determine a first time value according to the time values of the M cells.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, in M cells, time windows of receiving, by a clock synchronization apparatus, time values indicating transmission time of a frame boundary of a radio frame are different for different cells; a receiving unit, further configured to receive second indication information from the first network device, where the second indication information is used to indicate a time window of a time value indicating a transmission time of a frame boundary of a radio frame for a cell received in each of N cells, where the N cells include M cells; and a receiving unit, configured to receive the time values of the M cells according to the time window indicated by the second indication information.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a sending unit, configured to send third indication information to the first network device, where the third indication information is used for the first network device to allocate a cell to the clock synchronization apparatus, and the cell allocated to the clock synchronization apparatus includes M cells; the third indication information is the precision requirement of the clock synchronization device on the clock of the clock synchronization device; or, the third indication information is an identifier of the first service of the clock synchronization device or a QoS identifier of the first service, and the accuracy requirement of the first service of the clock synchronization device on the clock of the clock synchronization device is greater than the accuracy requirement of other services of the clock synchronization device on the clock of the clock synchronization device.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a receiving unit and a transmitting unit; a receiving unit, configured to receive a third time value sent by the first network device, where the third time value is used to indicate a sending time of a subframe boundary of a second cell of the second network device; the second obtaining unit is further configured to obtain a fourth time value after the handover to the second cell is performed, where the fourth time value is used to indicate a receiving time of a subframe boundary of the second cell; the determining unit is further configured to determine a transmission delay between the clock synchronization apparatus and the second network device according to the third time value and the fourth time value; and the transmission unit is used for transmitting data according to the transmission time delay of the clock synchronization device and the second network equipment.

With reference to the third aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a transmission unit; the first obtaining unit is further configured to obtain a System Frame Number (SFN) of the second cell after the handover to the second cell of the second network device, and receive a fifth time value sent by the second network device, where the fifth time value is used to indicate a sending time of a frame boundary of a wireless frame of the second cell; the second obtaining unit is further configured to obtain a sixth time value according to the SFN, where the sixth time value is used to indicate a receiving time of a frame boundary of a wireless frame of the second cell; the determining unit is further configured to determine a transmission delay between the clock synchronization apparatus and the second network device according to the fifth time value and the sixth time value; and the transmission unit is used for transmitting data according to the transmission time delay of the clock synchronization device and the second network equipment.

In a fourth aspect, embodiments of the present application provide a clock synchronization apparatus, which may include a unit or a means for performing the steps of the second aspect. Specifically, the clock synchronization apparatus may include: the device comprises an acquisition unit, a clock synchronization unit and a control unit, wherein the acquisition unit is used for acquiring the distance between a terminal and the clock synchronization unit and generating first information according to the distance; and the sending unit is used for sending first information to the terminal, wherein the first information is used for the terminal to determine the transmission time delay between the terminal and the clock synchronization device.

With reference to the fourth aspect, in a possible implementation manner, the sending unit is further configured to send, to the terminal, a time value indicating a sending time of a frame boundary of a radio frame through a cell allocated to the terminal, where the cell allocated to the terminal includes the first cell.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the first information is information used to indicate a transmission delay; alternatively, the first and second electrodes may be,

the first information is information indicating a distance between the terminal and the clock synchronization device.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: the acquisition unit is also used for acquiring the distance between the terminal and the clock synchronization device; and the sending unit is further configured to send the first information to the terminal again when the obtained distance between the terminal and the clock synchronization device is changed compared with the distance between the terminal and the clock synchronization device when the clock synchronization device issues the first information.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the cells allocated to the terminal include N cells, where frame boundaries of radio frames of the N cells are aligned, and N is an integer greater than or equal to 2.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the sending unit is specifically configured to send, to the terminal, a time value indicating a sending time of a frame boundary of a radio frame through each of N cells in different time windows; and the transmitting unit is further used for transmitting second indication information to the terminal, wherein the second indication information is used for indicating a time window of a time value of a transmitting time of a receiving cell indicating a frame boundary of a wireless frame in each cell of the N cells.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the clock synchronization apparatus may further include: a receiving unit and a distributing unit; a receiving unit, configured to receive third indication information from the terminal; the obtaining unit is further configured to obtain the number X of cells that need to be allocated to the terminal according to the third indication information; the distribution unit is used for distributing N cells for the terminal according to the number X, wherein N is greater than or equal to the number X; wherein: the third indication information is the precision requirement of the terminal on the clock of the terminal, and different precision requirements correspond to different numbers X; or, the third indication information is an identifier of the first service of the terminal, and the identifiers of different services correspond to different numbers X; or, the third indication information is a QoS identifier of the first service, and different QoS identifiers correspond to different numbers X; the accuracy requirement of the first service of the terminal on the clock of the terminal is greater than the accuracy requirement of other services of the terminal on the clock of the terminal.

With reference to the fourth aspect or the foregoing possible implementation manner, in another possible implementation manner, the receiving unit is further configured to receive a third time value sent by the second network device, where the third time value is used to indicate a sending time of a subframe boundary of a second cell of the second network device; and the sending unit is also used for sending the third time value to the terminal.

In a fifth aspect, an embodiment of the present application provides a clock synchronization apparatus, where the clock synchronization apparatus may include: a processor and interface circuitry, the processor being configured to communicate with other apparatus, such as a network device, via the interface circuitry and to perform the method provided in the first aspect above. The processor may include one or more.

In a sixth aspect, an embodiment of the present application provides a clock synchronization apparatus, which may include: a processor and an interface circuit, the processor being configured to communicate with other devices, such as a terminal, via the interface circuit and to perform the method provided by the second aspect above. The processor may include one or more.

In a seventh aspect, an embodiment of the present application provides a clock synchronization apparatus, where the clock synchronization apparatus may include a processor, configured to be connected to a memory, and configured to call a program stored in the memory to perform the method provided in the first aspect. The memory may be located within the device or external to the device. And the processor includes one or more.

In an eighth aspect, embodiments of the present application provide a terminal, which may include the clock synchronization apparatus provided in the second aspect.

In a ninth aspect, an embodiment of the present application provides a network device, which may include the clock synchronization apparatus provided in the third aspect.

In a tenth aspect, an embodiment of the present application provides a computer-readable storage medium, including: computer software instructions; the computer software instructions, when run in the clock synchronization apparatus or a chip built in the clock synchronization apparatus, cause the clock synchronization apparatus to perform the method of the first or second aspect above.

In an eleventh aspect, embodiments of the present application provide a clock synchronization program, which when executed by a processor is configured to perform the method of the first or second aspect.

In a twelfth aspect, embodiments of the present application provide a program product, such as a computer-readable storage medium, including the above program.

Therefore, in the aspects above, the terminal can obtain a more accurate transmission delay. Therefore, the terminal synchronizes the clock according to the obtained more accurate transmission delay, so that the clock synchronization error between the terminal and the first network equipment can be reduced.

As indicated above, the terminal may obtain the first information for determining the transmission delay, as received from the first network device. The first information may be a distance between the first network device and the terminal measured by the first network device in a radar or wireless positioning manner, or a transmission delay between the first network device and the terminal determined according to the measured distance.

In addition, the terminal determines the frame boundary of the wireless frame by acquiring the receiving time of the frame boundary of the wireless frames of the plurality of cells, so that the error of the terminal in determining the frame boundary of the wireless frame can be reduced, and the clock synchronization error between the terminal and the first network equipment is further reduced. When the first network device notifies the terminal of the time value, the transmitted radio frame of the time value has no time constraint, that is, the first network device may determine the radio frame notifying the terminal of the time value according to its own schedule. For example, in which radio frame the first network device is lightly loaded, which radio frame is used to notify the terminal of the time value. After the terminal is switched to the target cell (such as the second cell of the second network device), random access is not required, and the TA can be obtained through the accurate time of the sending time of the subframe boundary notified by the second network device or by reading the time service message of the target cell, so as to perform data transmission in the target cell.

Drawings

Fig. 1 is a schematic diagram of a communication system according to an embodiment of the present application;

fig. 2 is a schematic diagram of a network architecture according to an embodiment of the present application;

fig. 3 is a schematic diagram of another network architecture provided in the embodiments of the present application;

fig. 4 is a schematic transmission diagram of a time service message according to an embodiment of the present application;

fig. 5 is a schematic flowchart of a clock synchronization method according to an embodiment of the present application;

fig. 6 is a schematic flowchart of another clock synchronization method according to an embodiment of the present application;

fig. 7 is a schematic transmission diagram of another timing message provided in the embodiment of the present application;

fig. 8 is a schematic flowchart of another clock synchronization method according to an embodiment of the present application;

fig. 9 is a schematic transmission diagram of another timing service message provided in the embodiment of the present application;

fig. 10 is a schematic transmission diagram of another timing service message provided in the embodiment of the present application;

fig. 11 is a schematic flowchart of another clock synchronization method according to an embodiment of the present application;

fig. 12 is a schematic flowchart of another clock synchronization method according to an embodiment of the present application;

fig. 13 is a schematic structural diagram of a network device according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of a terminal according to an embodiment of the present application.

Detailed Description

In the following, some terms in the present application will be explained:

1) a terminal, also referred to as User Equipment (UE), a Mobile Station (MS), a Mobile Terminal (MT), etc., is a device that provides voice/data connectivity to a user. Such as an arm terminal in an industrial control network. For example, a handheld device or an in-vehicle device having a wireless connection function. Currently, some examples of terminals are: a mobile phone (mobile phone), a tablet computer, a notebook computer, a palm top computer, a Mobile Internet Device (MID), a wearable device, a Virtual Reality (VR) device, an Augmented Reality (AR) device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote surgery (remote medical supply), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety (smart security), a wireless terminal in city (smart city), a wireless terminal in smart home (smart home), and the like.

2) A network device is a device in a wireless network, such as a Radio Access Network (RAN) node that accesses a terminal to the wireless network. Currently, some examples of RAN nodes are: a gbb, a Transmission Reception Point (TRP), an evolved Node B (eNB), a Radio Network Controller (RNC), a Node B (NB), a Base Station Controller (BSC), a Base Transceiver Station (BTS), a home base station (e.g., a home evolved Node B or home Node B, HNB), a Base Band Unit (BBU), or a wireless fidelity (Wifi) Access Point (AP), etc. In one network configuration, a network device may include a Centralized Unit (CU) node, or a Distributed Unit (DU) node, or a RAN device including a CU node and a DU node.

3) The term "plurality" means two or more, and the other terms are similar. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. Furthermore, for elements (elements) that appear in the singular form "a," an, "and" the, "they are not intended to mean" one or only one "unless the context clearly dictates otherwise, but rather" one or more than one. For example, "a device" means for one or more such devices. Still further, at least one (at least one of.). said. "means one or any combination of subsequently associated objects, e.g.," at least one of a, B, and C "includes a, B, C, AB, AC, BC, or ABC.

Please refer to fig. 1, which is a schematic diagram of a communication system according to an embodiment of the present application. As shown in fig. 1, a terminal 101 (such as the arm terminal shown in fig. 1) accesses a wireless network to acquire a service of an external network (e.g., the internet) through the wireless network or to communicate with other terminals through the wireless network. The wireless network may include a RAN 102 and a Core Network (CN) 103. Among them, the RAN 110 is used to access the terminal 101 to a wireless network, and the CN 120 is used to manage the terminal and provide a gateway for communication with an external network.

Please refer to fig. 2, which is a schematic diagram of a network architecture according to an embodiment of the present application. As shown in fig. 2, the network architecture includes CN equipment and RAN equipment.

The RAN device includes a baseband device and a radio frequency device, where the baseband device may be implemented by one node or by multiple nodes, and the radio frequency device may be implemented independently by being pulled away from the baseband device, may also be integrated in the baseband device, or may be partially pulled away and partially integrated in the baseband device. For example, in a Long Term Evolution (LTE) communication system, a RAN equipment (eNB) includes a baseband device and a radio frequency device, where the radio frequency device may be remotely located with respect to the baseband device, e.g., a Remote Radio Unit (RRU) is remotely located with respect to a BBU.

The communication between the RAN equipment and the terminal follows a certain protocol layer structure. For example, the control plane protocol layer structure may include functions of protocol layers such as a Radio Resource Control (RRC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a physical layer (PHY). The user plane protocol layer structure can comprise functions of protocol layers such as a PDCP layer, an RLC layer, an MAC layer, a physical layer and the like; in one implementation, a Service Data Adaptation Protocol (SDAP) layer may be further included above the PDCP layer.

The functions of these protocol layers may be implemented by one node, or may be implemented by a plurality of nodes; for example, in an evolved structure, a RAN device may include a Centralized Unit (CU) and a Distributed Unit (DU), and a plurality of DUs may be centrally controlled by one CU. As shown in fig. 2, the CU and the DU may be divided according to protocol layers of the radio network, for example, functions of a PDCP layer and above protocol layers are provided in the CU, and functions of protocol layers below the PDCP layer, for example, functions of an RLC layer and a MAC layer, are provided in the DU.

This division of the protocol layers is only an example, and it is also possible to divide the protocol layers at other protocol layers, for example, at the RLC layer, and the functions of the RLC layer and the protocol layers above are set in the CU, and the functions of the protocol layers below the RLC layer are set in the DU; alternatively, the functions are divided into some protocol layers, for example, a part of the functions of the RLC layer and the functions of the protocol layers above the RLC layer are provided in the CU, and the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer are provided in the DU. In addition, the processing time may be divided in other manners, for example, by time delay, a function that needs to satisfy the time delay requirement for processing is provided in the DU, and a function that does not need to satisfy the time delay requirement is provided in the CU.

In addition, the radio frequency device may be pulled away, not placed in the DU, or integrated in the DU, or partially pulled away and partially integrated in the DU, which is not limited herein.

With continued reference to fig. 3, with respect to the architecture shown in fig. 2, the Control Plane (CP) and the User Plane (UP) of the CU may be separated and implemented by being divided into different entities, namely a control plane CU entity (CU-CP entity) and a user plane CU entity (CU-UP entity).

In the above network architecture, the signaling generated by the CU may be transmitted to the terminal through the DU, or the signaling generated by the terminal may be transmitted to the CU through the DU. The DU may pass through the protocol layer encapsulation directly to the terminal or CU without parsing the signaling. In the following embodiments, if transmission of such signaling between the DU and the terminal is involved, in this case, the transmission or reception of the signaling by the DU includes such a scenario. For example, the signaling of the RRC or PDCP layer is finally processed as the signaling of the PHY layer to be transmitted to the terminal, or converted from the received signaling of the PHY layer. Under this architecture, the signaling of the RRC or PDCP layer can also be considered to be sent by the DU, or by the DU and the radio frequency.

In the above embodiment, the CU is divided into the network devices on the RAN side, and in addition, the CU may also be divided into the network devices on the CN side, which is not limited herein.

The apparatus in the following embodiments of the present application may be located in a terminal or a network device according to the functions implemented by the apparatus. When the above structure of CU-DU is adopted, the network device may be a CU node, or a DU node, or a RAN device including the CU node and the DU node.

In the existing communication system, clock synchronization can be achieved between nodes that need to communicate with each other (e.g., between different network devices, between a network device and a terminal). The main ways of clock synchronization are currently GPS and 1588. However, this is not applicable to the terminal.

Therefore, a clock synchronization method applicable to a terminal is proposed. Specifically, the method comprises the following steps: the network device informs the terminal of a time value indicating the time of the ending position of a certain radio frame, and the terminal performs clock synchronization by using the time value and the transmission delay.

The time value notified to the terminal by the network device specifically indicates the time when the network device transmits the end position of the wireless frame. For example, as shown in fig. 4, the network device carries a time value indicating a time when the network device transmits the end position of the wireless frame M in the wireless frame M-2 and transmits the time value to the terminal. If so, the network device notifies the terminal in the wireless frame M-2: the time value corresponding to the end position of the wireless frame M is 485ms793.25us with 30 minutes and 28 seconds at 12, 22, 14 and 2018.

After receiving the wireless frame M-2, the terminal can know that the time value corresponding to the time when the network device sends the end position of the wireless frame M is 2018, 12, 22, 14, 30 min, 28 sec, 485 ms793.25us. The terminal may also detect the time at which the end position of the radio frame M is received. For example, the time when the terminal detects the end position of the radio frame M is T1.

Since there is a transmission delay between the network device and the terminal, the sum of the time value corresponding to the time at which the network device sends the ending position of the wireless frame M and the transmission delay obtained by the terminal should be equal to the time value corresponding to the time at which the terminal detects the ending position of the wireless frame M. Thus, the synchronization of the terminal clock and the network equipment clock can be realized. That is, the terminal may determine, according to the obtained time value and the transmission delay corresponding to the time when the network device transmits the ending position of the wireless frame M, the time value corresponding to the time (such as T1) when the terminal detects the ending position of the wireless frame M. If the transmission delay is 200us, the terminal may determine that T1 corresponds to a time value of 30 minutes, 28 seconds, 485ms993.25us at 12 months, 22 days, 14 hours in 2018. In this way, the clocks between the terminal and the network device are synchronized.

It can be seen that the terminal needs to know the transmission delay between the network device and the terminal, and can perform clock synchronization according to the time value notified by the network device. The terminal may determine a Timing Advance (TA), and then use one half of the TA as the transmission delay.

There is an error in the clock synchronization using the above method. The error introduced by this method can be seen in table 1. As can be seen from table 1, the timing error type (timing error type) under this method may include: the base station transmits frame timing (BS transmit frame timing), the UE receives frame timing (UE receiving frame timing), the UE transmits frame timing (UE transmit frame timing (TA adjustment accuracy)), the TA adjustment granularity (TA adjustment granularity), and the base station receives frame timing (BS receiving frame timing). In addition, in different sub-carrier spacing (SCS), errors introduced by the same timing error type may be different, and Total timing error (Total timing error) may also be different. For example, when SCS equals 15kHz, the error introduced by the UE receiving frame timing is [12] × 64 × Tc (Tc is the minimum time unit), and the total timing error is [38] × 64 × Tc. When SCS equals 30kHz, the error introduced by the UE receiving frame timing is [8] x 64Tc, and the total timing error is [26] x 64 Tc.

TABLE 1

In table 1, the UE transmission frame timing (TA adjustment accuracy), the TA adjustment granularity, and the base station reception frame timing are all from TA. That is, the TA error determined by the terminal is large. If one half of TA is taken as the transmission delay, this will make the error of the transmission delay determined by the terminal larger, and thus the error of the synchronization of the clocks between the terminal and the network device is larger.

Based on this, a clock synchronization method is provided: the network device measures the distance between the network device and the terminal by using a radar or wireless positioning mode, and informs the terminal of the measured distance or the transmission delay between the network device and the terminal determined according to the measured distance. The propagation delay obtained in this way is more accurate than the propagation delay determined by the TA. That is, the terminal can obtain a more accurate transmission delay. Therefore, the terminal synchronizes the clock according to the acquired more accurate transmission delay, so that the synchronization error of the clock between the terminal and the network equipment can be reduced.

It should be noted that the clock synchronization method described in the embodiment of the present application may be applied to an industrial control network. The industrial control network may be based on the communication system shown in fig. 1 described above. As an example, the communication system may be a 5G NR system, and of course, the communication system may also be another communication system, as long as the communication system is supported by an industrial control network, and the embodiment of the present application is not limited specifically herein.

The clock synchronization method provided by the embodiments of the present application is described in detail below with reference to the accompanying drawings.

Fig. 5 is a schematic flowchart of a clock synchronization method according to an embodiment of the present application, and as shown in fig. 5, the method may include:

501. the first network device sends the first information to the terminal.

502. And the terminal acquires the first information, wherein the first information is used for determining the transmission delay between the terminal and the first network equipment.

In some embodiments, the first information may be information indicating a transmission delay of the terminal with the first network device. The first information may specifically be the transmission delay itself, or may be indication information for indicating the transmission delay.

The first information in this embodiment is different from TA in that it is not obtained through signaling interaction between the network device and the terminal, and has a characteristic of more accurately representing a distance or a time delay between the network device and the terminal.

For example, the first network device may obtain a distance between the terminal and the first network device. For example, the first network device may obtain the distance between the terminal and the first network device through radar measurement. The first network device can also measure the distance between the terminal and the first network device by means of wireless positioning. The distance obtained by the first network device may be a result obtained through one measurement, or may be a result obtained by averaging or weighted averaging results obtained through multiple measurements.

The first network device may generate the first information according to the acquired distance. For example, the first network device may determine the transmission delay between the terminal and the first network device according to the obtained distance between the terminal and the first network device.

For example, the first network device may determine the transmission delay between itself and the terminal by dividing the obtained distance by the speed of light. Also for example, there may be a multipath offset between the first network device and the terminal. The first network device may also take into account the transmission delay caused by the multipath offset when determining the transmission delay with the terminal. For example, the terminal is an operation arm terminal located in a factory building. Various obstructions may exist between the first network device and the arm terminal, resulting in a multipath offset between the first network device and the arm terminal. Therefore, the first network device may determine the transmission delay 1 by dividing the obtained distance between the operation arm terminal and the first network device by the speed of light, and determine the transmission delay 2 caused by the multipath offset according to the channel transmission model. The first network device may obtain the transmission delay between the operation arm terminal and the first network device according to the transmission delay 1 and the transmission delay 2 (for example, the transmission delay between the operation arm terminal and the first network device is obtained by summing the transmission delay 1 and the transmission delay 2).

Wherein, the channel transmission model is determined by the first network device and includes probability distribution of transmission delay at different distances (distance between the terminal and the first network device), for example, at the first distance, the transmission delay t _1 of the line-of-sight direct transmission path has a probability of 95%, and the transmission delay t of the non-line-of-sight path is t% _—2, the probability is 5%; and under the second distance, the probability of the transmission delay t _3 of the line-of-sight direct transmission path is 90%, the probability of the transmission delay t _4 of the non-line-of-sight path is 10%, and the like. The first network device determines the transmission delay 2 caused by the multipath offset by using the channel transmission model according to the distance between the terminal and the first network device. If the distance between the terminal of the operating arm and the first network device is the first distance, the transmission delay 2 is equal to the sum of t _1 × 95% and t _2 × 5%. The first network device may thenAnd informing the obtained transmission delay or indication information for indicating the transmission delay to the terminal.

Accordingly, the terminal can acquire the transmission delay or the indication information for indicating the transmission delay. If the terminal acquires the indication information for indicating the transmission delay, the terminal can determine the transmission delay between the terminal and the first network device according to the acquired indication information for indicating the transmission delay.

In still other embodiments, the first information may be information indicating a distance between the terminal and the first network device. The first information may be a distance between the terminal and the first network device, or may be indication information for indicating the distance. That is, the first network device may transmit the obtained distance or indication information indicating the distance to the terminal after acquiring the distance between the terminal and the first network device. Accordingly, the terminal may obtain the distance between the terminal and the first network device or the indication information for indicating the distance. According to the obtained distance between the terminal and the first network device or the indication information for indicating the distance, the terminal can determine the transmission delay between the terminal and the first network device.

Of course, the first network device may also send the channel transmission model to the terminal if the transmission delay caused by the multipath offset between the first network device and the terminal is taken into account. In this way, the terminal may determine the transmission delay between the terminal and the first network device according to the acquired information indicating the distance between the terminal and the first network device and the channel transmission model. The first network device may carry the channel transmission model and information indicating the distance between the terminal and the first network device in the same information (e.g., first information) and transmit the same information to the terminal, or may carry the channel transmission model and information indicating the distance between the terminal and the first network device in different information and transmit the same information to the terminal, which is not limited in this embodiment. It should be noted that, in this embodiment, the specific implementation of determining the transmission delay by the terminal may refer to the specific implementation of determining the transmission delay by the first network device, and details are not described here.

It should be noted that, in the above example, the first information is sent by the first network device to the terminal, that is, the step 502 may specifically be that the terminal receives the first information from the first network device. Of course, the first information may also be obtained by the terminal in other manners, that is, the transmission delay between the terminal and the first network device may be obtained by the terminal in other manners. For example, the terminal may obtain the distance between itself and the first network device through radar measurement, and then determine the transmission delay with the first network device according to the measured distance. For another example, the terminal may measure a distance between itself and the first network device by using its own positioning module, and then determine the transmission delay with the first network device according to the measured distance. For another example, the terminal may further obtain a distance between itself and the first network device according to the configuration of the background, and then determine the transmission delay with the first network device according to the obtained distance. When the terminal obtains the first information by other means, the above step 501 may not be performed.

503. The first network equipment transmits a time value indicating the transmission time of a frame boundary of a wireless frame to the terminal through a cell allocated to the terminal, wherein the cell allocated to the terminal comprises the first cell.

The frame boundary of the radio frame may be a start position or an end position of the radio frame. In addition, since the time value sent by the first network device to the terminal indicates the time when the first network device sends the frame boundary of the radio frame, for convenience of description, in the embodiment of the present application, the time when the first network device sends the frame boundary of the radio frame indicated by the time value sent by the first network device to the terminal is referred to as the sending time of the frame boundary of the radio frame.

The first network device may notify the terminal of a time value indicating a transmission time of a start position or an end position of a certain radio frame through a cell allocated to the terminal, and the notified time value may be used for the terminal to perform clock synchronization. In some embodiments, the first network device may send, to the terminal, a time service message through a cell allocated to the terminal, where the time service message carries a time value indicating a sending time of a start position or an end position of the radio frame.

For example, the cell allocated to the terminal includes a first cell, and a frame boundary of a radio frame is taken as an end position. The first network device may send, through the first cell, a time service message to the terminal in the wireless frame M-2, where the time service message carries a time value (e.g., referred to as a first time value), and the time value may be used to indicate a sending time of the end position of the wireless frame M. The time service message can be sent to the terminal in a broadcasting mode or a special signaling mode.

It should be noted that, the first network device may periodically transmit, to the terminal, a time value indicating a transmission time of a frame boundary of the radio frame through a cell allocated to the terminal, so that the terminal performs clock synchronization. The first network device may also send the time value indicating the sending time of the frame boundary of the radio frame to the terminal through the cell allocated to the terminal at an irregular time, for example, the first network device may send the time value indicating the sending time of the frame boundary of the radio frame to the terminal through the cell allocated to the terminal when determining that the clock of the first network device has a jump, so as to perform clock synchronization for the terminal.

504. The terminal acquires a first time value, which is used for indicating the sending time of the frame boundary of the wireless frame of the first cell of the first network equipment.

For example, in combination with the example in step 503, step 504 may specifically be: the terminal receives a time service message sent by the first network device in the wireless frame M-2 through the first cell to obtain a time value used for indicating the sending time of the ending position of the wireless frame M of the first cell, namely, a first time value. As the first time value: 12/29/13/14/36/s 587ms323.25us in 2018.

505. And the terminal determines a second time value corresponding to the receiving moment of the frame boundary of the wireless frame of the first cell according to the transmission delay and the first time value.

For a terminal, it may obtain a time of a frame boundary (a start position or an end position) of a certain radio frame through sync sequence detection, and a subsequent terminal starts receiving or ends receiving the radio frame at the time, so for convenience of description, in this embodiment, the time of the frame boundary of the radio frame detected by the terminal is referred to as a receiving time of the frame boundary of the radio frame. It should be noted that the time (e.g., receiving time, transmitting time) described in the embodiments of the present application refers to a point on a time axis. The time value corresponding to the time (e.g., the time value corresponding to the reception time, and the time value corresponding to the transmission time) refers to a coordinate value corresponding to this point on the time axis.

Theoretically, the time value corresponding to the receiving time of the frame boundary of the wireless frame detected by the terminal should be equal to the sum of the time value corresponding to the transmitting time of the frame boundary of the wireless frame and the transmission delay, so that the clocks of the terminal and the first network device are synchronized. Therefore, after the terminal acquires the transmission delay between the terminal and the first network device and the first time value used for indicating the sending time of the frame boundary of the wireless frame of the first cell, the transmission delay is added to the first time value, and the terminal can determine the second time value corresponding to the receiving time of the frame boundary of the wireless frame, so that clock synchronization between the terminal and the first network device is realized.

For example, in combination with the above examples of step 502 and step 504, the terminal may obtain a transmission delay (e.g., 300us of transmission delay) and a first time value (e.g., first time value: 14 min 36 s 587ms323.25us on 13 th 24 th 12 th 29 th 2018) indicating the transmission time of the end position of the radio frame M of the first cell, and may also perform synchronization sequence detection to obtain the reception time (e.g., T1) of the end position of the radio frame M of the first cell. The terminal adds the first time value and the transmission delay to determine a second time value corresponding to the receiving time T1 of the ending position of the wireless frame M of the first cell, wherein the second time value is 587ms623.25us, 12 years, 29 months, 13 hours, 14 minutes, 36 seconds.

According to the clock synchronization method provided by the embodiment of the application, the terminal can obtain more accurate transmission time delay. Therefore, the terminal synchronizes the clock according to the obtained more accurate transmission delay, so that the clock synchronization error between the terminal and the first network equipment can be reduced. For example, the terminal may receive first information from a first network device for determining a transmission delay. The first information may be a distance between the first network device and the terminal measured by the first network device in a radar or wireless positioning manner, or a transmission delay between the first network device and the terminal determined according to the measured distance.

For example, the terminal is an operation arm terminal. Assuming that the distance between the arm terminal and the first network device is 100 meters, the radius of the moving range of the arm terminal is 10 meters. That is, the distance between the terminal of the operation arm and the first network device is 90 m to 110 m, and the transmission delay obtained by dividing the distance by the speed of light is about 0.3us to 0.36 us. And the transmission delay is 0.3us-0.4us when the distance between the operating arm terminal and the first network equipment is measured to be 90 m-110 m. Therefore, the error due to the propagation delay measurement is about 0.1us (0.4-0.36 us ═ 0.04us, about 0.1 us). By adopting the method for calculating TA, and taking SCS equal to 15kHz as an example in combination with table 1, the determined error of the transmission delay reaches 0.78 us.

Optionally, in order to enable the terminal clock synchronization result to be more accurate, in some embodiments, the time precision of the transmission delay determined according to the first information may be less than or equal to the time precision of the first time value. For example, the time precision of the first time value is 250ns, and taking the first information as the transmission delay of the terminal and the first network device itself as an example, the time precision of the transmission delay sent by the first network device to the terminal may be less than or equal to 250 ns. The smaller the time accuracy, the more accurate the result of the terminal clock synchronization.

The terminal may be in a mobile state. As the terminal moves, the distance between the terminal and the first network device changes, and the transmission delay between the terminal and the first network device changes accordingly. Therefore, in some embodiments, the terminal may periodically acquire the first information, so as to periodically determine the transmission delay according to the first information, thereby performing clock synchronization, so as to further reduce a synchronization error of the clock between the terminal and the first network device.

For example, taking the first information sent to the terminal by the first network device as an example, the first network device may periodically obtain the distance between the terminal and the first network device, and periodically send the first information to the terminal. If the first information is the transmission delay itself between the terminal and the first network device, the first network device may measure the distance between the terminal and the first network device at regular intervals (e.g., 5 minutes, 30 minutes, etc.), and notify the terminal of the transmission delay between the terminal and the first network device determined according to the measurement result. If the first information is the distance itself between the terminal and the first network device, the first network device may measure the distance between the terminal and the first network device at regular intervals, and notify the terminal of the measurement result. In this way, the terminal can periodically acquire the first information for clock synchronization.

In some other embodiments, if the first information is sent to the terminal by the first network device, the first network device may also monitor the distance between the terminal and the first network device after sending the first information to the terminal. If the distance between the terminal and the first network device is detected to be changed, the first network device can issue the first information to the terminal again, so that the terminal determines the transmission delay with the first network device according to the first information issued again, and clock synchronization is performed.

For example, the first information is the transmission delay itself between the terminal and the first network device. After the first network device issues the transmission delay 1 to the terminal, the distance between the terminal and the first network device may be monitored. If the obtained distance between the terminal and the first network device at the current moment is changed compared with the distance between the terminal and the first network device when the transmission delay 1 is issued, the first network device may determine the transmission delay 2 according to the distance between the terminal and the first network device at the current moment, and notify the terminal of the transmission delay 2, and the terminal may perform clock synchronization according to the transmission delay 2. . For another example, the first information is the distance between the terminal and the first network device itself. After the first network device issues the distance 1 (the distance between the terminal and the first network device) to the terminal, the first network device may monitor the distance between the terminal and the first network device. If the obtained distance 2 between the terminal and the first network device at the current moment is changed compared with the distance 1, the first network device can inform the terminal of the distance 2, and the terminal can determine transmission delay according to the distance 2 for clock synchronization.

In some other embodiments, the terminal may also monitor the moving distance of the terminal after acquiring the first information (e.g., the terminal may measure the moving distance of the terminal by radar, wireless (e.g., Wifi) positioning, artificial intelligence analysis, image analysis, and the like), and if it is detected that the moving distance is greater than (or equal to) the distance threshold, it is indicated that the distance between the terminal and the first network device may change, and the transmission delay of the terminal and the first network device may change. At this time, the terminal may reacquire the first information, so as to determine the transmission delay according to the reacquired first information, thereby performing clock synchronization, so as to further reduce a clock synchronization error between the terminal and the first network device.

For example, the first information is sent to the terminal by the first network device. After the terminal receives the first information sent by the first network device, the terminal may obtain a moving distance from the time when the terminal obtains the first information to the current time. If the obtained moving distance is greater than the distance threshold, the terminal may send first indication information to the first network device, where the first indication information is used to indicate the first network device to resend the first information. If the first information is the transmission delay itself between the terminal and the first network device, the first network device may obtain the distance between the terminal and the first network device again after receiving the first indication information, and notify the terminal of the transmission delay between the terminal and the first network device determined according to the obtained distance result, and the terminal may perform clock synchronization according to the transmission delay obtained again. Also, for example, if the first information is the distance between the terminal and the first network device itself, the first network device may obtain the distance between the terminal and the first network device again after receiving the first indication information, and notify the obtained distance to the terminal, and the terminal may determine the transmission delay according to the obtained distance again, so as to perform clock synchronization.

In addition, with reference to table 1, it can be seen that an error is also introduced into the UE receiving frame timing during the clock synchronization. For example, when the SCS is equal to 15kHz, the error introduced by the UE receiving frame timing is [12] × 64 × Tc, and when the SCS is equal to 30kHz, the error introduced by the UE receiving frame timing is [8] × 64 × Tc. That is, there is an error (the error may reach 390ns) in the frame boundary of the radio frame determined by the terminal, that is, the receiving time of the detected frame boundary of the radio frame, and this error also affects the clock synchronization precision between the terminal and the first network device. In order to further reduce the clock synchronization error between the terminal and the first network device, further, before the terminal determines the second time value corresponding to the receiving time of the frame boundary of the radio frame of the first cell according to the transmission delay and the first time value, that is, before step 505, as shown in fig. 6, the clock synchronization method may further include the following steps:

601. the terminal acquires the receiving time of the frame boundaries of the wireless frames of the M cells, the frame boundaries of the wireless frames of the M cells are aligned, the M cells comprise a first cell, and M is an integer greater than or equal to 2.

602. And the terminal updates the receiving time of the frame boundary of the wireless frame of the first cell according to the receiving time of the frame boundary of the wireless frame of the M cells.

For example, in order to reduce an error when the terminal determines the frame boundary of the radio frame, the first network device may allocate a plurality of cells to the terminal, and the frame boundaries of the radio frames of the plurality of cells are aligned. Specifically, from the perspective of the first network device, the frame boundaries of the radio frames of the multiple cells are aligned. For example, as shown in (a) of fig. 7, the first network device allocates two cells to the terminal, namely, cell 1 and cell 2, and from the perspective of the first network device, the frame boundaries of the radio frame of cell 1 and the radio frame of cell 2 are aligned, that is, the frame boundaries of radio frame M-2 of cell 1 and radio frame M-2 of cell 2 are aligned, the frame boundaries of radio frame M-1 of cell 1 and radio frame M-1 of cell 2 are aligned, and the frame boundaries of radio frame M of cell 1 and radio frame M of cell 2 are aligned.

In addition, after the first network device allocates multiple cells to the terminal, a notification message may be sent to the terminal, where the notification message is used to notify that the terminal allocates multiple cells to the terminal, and the frame boundaries of the radio frames of the multiple cells are aligned. It should be noted that, according to the protocol, when the network device transmits a radio frame, the frame boundary may shift forward or backward by 64Tc, but the network device is not aware of it. That is, the alignment of the frame boundaries of the radio frames in which a plurality of cells are allocated to the terminal is not strictly aligned, and the frame boundaries of different cells may be considered to be aligned when there is a deviation of less than 64Tc between the frame boundaries.

In this way, before performing clock synchronization according to the transmission delay and the first time value, the terminal may perform frame boundary detection on the radio frames of the plurality of cells allocated to the terminal by the first network device, that is, the terminal acquires the receiving time of the frame boundaries of the radio frames of the plurality of cells, where the receiving time includes the receiving time of the frame boundary of the radio frame of the first cell. Since transmission paths of signals in different cells are not completely the same, transmission delays of the terminal and the first network device in different cells are also not necessarily the same, and thus, reception times of frame boundaries of radio frames of multiple cells acquired by the terminal are usually different. Therefore, after the receiving time of the frame boundaries of the wireless frames of the multiple cells is obtained, the terminal may update the receiving time of the frame boundary of the wireless frame of the first cell according to the obtained receiving time of the frame boundaries of the wireless frames of the multiple cells, so as to reduce an error when determining the frame boundary of the wireless frame, that is, obtain a more accurate receiving time of the frame boundary of the wireless frame of the first cell. After determining the more accurate receiving time of the frame boundary of the wireless frame of the first cell, the terminal may perform step 505, that is, determine a second time value corresponding to the receiving time of the frame boundary of the wireless frame of the first cell according to the transmission delay and the first time value, so as to complete clock synchronization.

It should be noted that the radio frame referred to herein is the same radio frame as the radio frame indicated by the first time value in step 504. For example, in step 504, the first time value indicates the transmission time of the frame boundary of the wireless frame M of the first cell (e.g., cell 1), and the wireless frame refers to the wireless frame M, i.e., the reception time of the frame boundary of the wireless frame M of multiple cells acquired by the terminal.

For example, in combination with the above step 504 and the example shown in fig. 7 (a), the frame boundary of the radio frame is taken as the ending position. The terminal may acquire the reception time of the end position of the radio frame M of the cell 1 and the reception time of the end position of the radio frame M of the cell 2. As shown in fig. 7 (b), the reception time at which the terminal acquires the end position of the radio frame M in cell 1 is T1, and the reception time at which the terminal acquires the end position of the radio frame M in cell 2 is T2. If the cell 1 is the first cell, after acquiring the receiving time T1 of the ending position of the radio frame M of the cell 1 and the receiving time T2 of the ending position of the radio frame M of the cell 2, the terminal may take an average value of T1 and T2 (T1 and T2 may also be weighted and averaged, and a weighted value corresponding to each cell may be configured for the terminal by the first network device), and if the obtained result is T12, update the T12 to the receiving time of the ending position of the radio frame M of the cell 1. At this time, the terminal may determine a second time value corresponding to the receiving time T12 of the ending position of the radio frame M of the cell 1, such as 14 minutes 36 seconds 587ms623.25us at 13 time of 29 th 12 th 2018, according to the transmission delay (such as the transmission delay of 300us) and the first time value (such as the first time value: 14 minutes 36 seconds 587ms323.25us at 13 time of 29 th 12 th 2018), so as to complete clock synchronization.

It should be noted that, in the description here, it is assumed that the radio frame numbers of the cells allocated to the terminal by the first network device are aligned, as with the example of fig. 7, the terminal acquires the receiving time of the frame boundary of the radio frame M of cell 1, and acquires the receiving time of the frame boundary of the radio frame M of cell 2. In practical use, the radio frame numbers of the multiple cells allocated to the terminal by the first network device may also be unaligned, and it is only necessary to ensure that the frame boundaries of the radio frames of the multiple cells are aligned.

Therefore, the terminal determines the frame boundary of the wireless frame by acquiring the receiving time of the frame boundary of the wireless frames of the plurality of cells, so that the error of the terminal in determining the frame boundary of the wireless frame can be reduced, and the clock synchronization error between the terminal and the first network equipment is further reduced.

In addition, as shown in fig. 8, the step 504 of acquiring, by the terminal, the first time value may specifically include the following steps:

801. the terminal receives time values indicating transmission timings of frame boundaries of radio frames for the M cells.

Wherein frame boundaries of radio frames of the M cells are aligned, the M cells include a first cell, and M is an integer greater than or equal to 2.

802. And the terminal determines a first time value according to the time values of the M cells.

For example, in order to reduce an error of the second time value corresponding to the reception time of the radio frame determined by the terminal, the first network device may send, to the terminal, the time value indicating the transmission time of the frame boundary of the radio frame of the cell through a plurality of cells allocated to the terminal, respectively. That is, step 503 may be specifically configured to allow the first network device to transmit, to the terminal, the time value indicating the transmission time of the frame boundary of the radio frame of the cell, through the plurality of cells allocated to the terminal. For example, the first network device sends a time service message to the terminal through a plurality of cells allocated to the terminal, where the time service message carries a time value indicating a sending time of a frame boundary of a radio frame of the cell. The frame boundaries of the radio frames of the plurality of cells are aligned, the plurality of cells including the first cell. In this way, the terminal can receive time values indicating the transmission time of the frame boundary of the radio frame for a plurality of cells.

In addition, the first network device may or may not indicate to the terminal the time value of the transmission time of the frame boundary of the same radio frame of the plurality of cells. If the time value of the transmission time of the frame boundary of the same radio frame is indicated, the terminal may average or weighted average the received time values of the multiple cells (where the weighted value corresponding to each cell may be configured by the first network device to the terminal), so as to determine the first time value. If the indicated time value is not the time value of the transmission time of the frame boundary of the same wireless frame, the terminal can calculate the time value of the transmission time of the frame boundary of the same wireless frame (the same wireless frame refers to the same wireless frame as the wireless frame indicated by the first cell), and then determine the first time value according to the calculated time value and the received time value of the transmission time of the frame boundary of the indicated wireless frame of the first cell. The "same radio frame" refers to a radio frame with aligned time boundaries when transmitted by the first network device, and the radio frame numbers of the same radio frame in different cells may be the same or different.

For example, as shown in (a) of fig. 9, the first network device allocates two cells to the terminal, namely cell 1 and cell 2, and from the perspective of the first network device, the frame boundaries of the radio frame of cell 1 and the radio frame of cell 2 are aligned, that is, the frame boundaries of radio frame M-2 of cell 1 and radio frame N-2 of cell 2 are aligned, the frame boundaries of radio frame M-1 of cell 1 and radio frame N-1 of cell 2 are aligned, and the frame boundaries of radio frame M of cell 1 and radio frame N of cell 2 are aligned. The radio frame M of the cell 1 and the radio frame N of the cell 2 are "the same radio frame", and have different radio frame numbers. Take the frame boundary as the end position as an example. The first network device may transmit, to the terminal, through cell 1 (e.g., through radio frame M-2 of cell 1), time value 1 indicating the transmission time of the end position of radio frame M of cell 1, e.g., time value 1 is 14 minutes, 36 seconds 587ms323.25us at 13 days 13 of 12 months 29 of 2018. The first network device may transmit, to the terminal, through cell 2 (e.g., through radio frame N-1 of cell 2), time value 2 indicating the transmission time of the end position of radio frame N of cell 2, e.g., time value 2 is 2018, 12, 29, 13, 14 minutes, 36 seconds 587 ms323.50us. Accordingly, the terminal may receive a time value 1 of cell 1 indicating the transmission time of the end position of the radio frame M and a time value 2 of cell 2 indicating the transmission time of the end position of the radio frame N. The terminal may average the received time value 1 and time value 2 to determine the first time value. If the result is a time value of 12: in 2018, 12, 29, 13 hours, 14 minutes, 36 seconds, 587ms323.375us, and the time value 12 is the first time value.

Of course, after the terminal determines the first time value, a second time value corresponding to the receiving time of the ending position of the wireless frame M of the cell 1 may be determined according to the first time value and the transmission delay (for example, the transmission delay is 300us), for example, 14 minutes, 36 seconds, 587ms623.375us when 13, 12, 29, 2018, and 24 minutes, so as to complete clock synchronization. As shown in fig. 9 (b), the reception time of the end position of the radio frame M in the cell 1 may be T1 shown in fig. 9 (b) or T12. T1 may be obtained by the terminal performing frame boundary detection on the radio frame M indicated by the time value 1. T12 may be obtained by the terminal according to T1 and T2, and T2 is obtained by the terminal after performing frame boundary detection on the radio frame N indicated by the time value 2. The specific description of determining T12 may refer to the specific description of the corresponding content in the embodiment shown in fig. 6, and is not described in detail here.

In this way, when the first network device notifies the terminal of the time value, the transmitted radio frame of the time value has no time constraint, that is, the first network device may determine the radio frame notifying the terminal of the time value according to its own schedule. For example, in which radio frame the first network device is lightly loaded, which radio frame is used to notify the terminal of the time value.

In addition, as described in step 503 above, the first network device may transmit the time service message to the terminal by using a broadcast or dedicated signaling mode through the cell allocated to the terminal, so as to notify the terminal of the time value of the transmission time of the frame boundary of the wireless frame in the cell. When the number of terminals in a cell is large, the first network device generally transmits the time service message in a broadcast manner, and in this manner, the time service message is periodically transmitted.

When the terminal has a higher requirement on the accuracy of its own clock, the first network device may be required to send the time service message more frequently in a cell due to the clock drift of the terminal, that is, the terminal needs to read the time service message more frequently. Otherwise, in the latter half of a time service message sending period, the clock maintained by the terminal may drift too much and exceed the threshold, so that the requirement on the clock precision cannot be met. In this case, the first network device may achieve the purpose by reducing the transmission cycle of the time service message. However, this occupies more wireless resources, and the transmission period of the time service message is usually the transmission period of the reused system information, and if the transmission period of the system information (or called system message window) is reduced, other unrelated terminals are forced to read the system information multiple times, which is obviously unnecessary.

In this embodiment of the present application, when the first network device allocates multiple cells to the terminal, and under the condition that the transmission cycle of the time service message in each cell is not changed, the first network device may ensure that the transmission cycles of the time service messages in each cell of the multiple cells are staggered, that is, step 503 specifically may include: the first network device transmits a time value indicating a transmission timing of a frame boundary of a radio frame to the terminal through each of a plurality of cells allocated to the terminal in different time windows. In this way, the time windows in which the terminal receives the time values indicating the transmission times of the frame boundaries of the radio frames of different cells are different. That is, it is not necessary for the first network device to frequently send the time service message in one cell, nor to reduce the sending period of the system message, and for the terminal, by reading the time service messages of multiple cells (the time service message carries the time value indicating the sending time of the frame boundary of the wireless frame), it is possible to reduce the period of reading the time service message of a cell, and the purpose of reading the time service message more frequently is achieved.

For example, as shown in fig. 10, the first network device allocates two cells, cell 1 and cell 2, respectively, to the terminal. The first network device sends a time service message to the terminal through the cell 1 in the time window 1, where the time service message carries a time value (e.g., time value (time)1 in fig. 10) indicating a sending time of a frame boundary of the radio frame in the cell 1. The first network device sends a time service message to the terminal through the cell 2 in the time window 2, where the time service message carries a time value (e.g., time value (time)2 in fig. 10) indicating a sending time of a frame boundary of the radio frame in the cell 2. The

time windows

1 and 2 are different and staggered.

Of course, the first network device may send, to the terminal, second indication information for indicating a time window in which the terminal receives, in each of a plurality of cells of the first network device allocated to the terminal, a time value of a transmission time of a frame boundary indicating a radio frame of the cell. Before the above step 801, the terminal may receive the second indication information from the first network device. In this way, the terminal may receive the time values of the plurality of cells allocated to the terminal by the first network device according to the time window indicated by the second indication information. For example, referring to fig. 10, the first network device may send, to the terminal, second indication information indicating a time window 1 for the terminal to receive the time service message in cell 1 and a time window 2 for the terminal to receive the time service message in cell 2. The terminal can receive the time service messages in the cell 1 and the cell 2 respectively according to the time window 1 and the time window 2 indicated by the second indication information so as to obtain the time value of the cell 1 indicating the sending time of the frame boundary of the wireless frame and the time value of the cell 2 indicating the sending time of the frame boundary of the wireless frame. And because the time window 1 and the time window 2 are staggered, the terminal can read the time service message more frequently, so that the synchronized clock precision can meet the requirement of the terminal.

It should be noted that the multiple cells allocated to the terminal may be located in the same network device, or may be located in different network devices. If a plurality of cells are located in the same network device, the network device may internally and automatically ensure that the transmission periods of the time service messages of each cell in the plurality of cells are staggered.

If the plurality of cells are located in different network devices, the network devices may interact with each other to ensure that transmission periods of the time service messages of each cell in the plurality of cells are staggered. For example, a plurality of cells are respectively located at network device 1 and network device 2. Network device 1 may send a time window of time values indicating the sending time of the frame boundary of the radio frame located in each cell of network device 1 to network device 2, for example, network device 1 notifies network device 2, the time window (or referred to as time service period, sending period) of time service message sent by network device 1 is Y1 radio frames, the time window of time service message sent at a certain time (e.g. the first time) is from which radio frame to which radio frame, and the time service message is next prepared to be sent on the radio frame with radio frame number i. Network device 2 may also notify network device 1 of a time window of a time value indicating a transmission time of a frame boundary of a radio frame located in each cell of network device 2 to network device 1, for example, network device 2 notifies network device 1 that the time window for network device 2 to transmit a time service message (or referred to as a time service period, or a transmission period) is Y2 radio frames, and from which radio frame to which radio frame the time window for transmitting the time service message at a certain time (e.g., the first time) is, the time service message is to be prepared to be transmitted at the radio frame with the radio frame number j next time. Through interaction among the network devices, the transmission periods of the time service messages of each cell in a plurality of cells allocated to the terminal can be finally ensured to be staggered. In addition, in the process, the information exchanged between the network devices is notified to the terminal, and the network devices may or may not read the information.

In some embodiments, as described in the embodiments shown in fig. 6 and fig. 8, it can be understood that the first network device may reduce the error of clock synchronization by allocating a plurality of cells to the terminal to reduce the error when the terminal determines the frame boundary of the radio frame and/or reduce the error when the terminal determines the time value corresponding to the receiving time of the radio frame. Obviously, the more cells are allocated to the terminal, the smaller the error will be, the smaller the error of clock synchronization, and the higher the accuracy of the terminal clock will be. However, the larger the number of cells allocated to the terminal, the larger the data processing amount of the terminal, and the more power consumption. Considering different terminals, different services of the terminals have different requirements on the clock accuracy, and therefore, the first network device may allocate an appropriate number of cells to the terminal according to the indication of the terminal. That is, the embodiment of the present application may further include: and the terminal sends third indication information to the first network equipment, wherein the third indication information is used for the first network equipment to allocate the cell for the terminal. The first network device may receive third indication information from the terminal, and allocate an appropriate number of cells to the terminal according to the third indication information.

In some embodiments, the third indication information may be an accuracy requirement of the terminal on a clock of the terminal. For example, the terminal may report to the first network device an error requirement of its own reception time of the frame boundary of the determined radio frame, for example, the error is within XXXXns. The first network device allocates a suitable number of cells to the terminal based on the error requirement.

In other embodiments, the third indication information may be an identifier of the first service of the terminal or a quality of service (QoS) identifier of the first service. The accuracy requirement of the first service of the terminal on the clock of the terminal is greater than the accuracy requirement of other services of the terminal on the clock of the terminal. For example, the terminal may report, to the first network device, an identifier of a service (i.e., the first service) that has a highest requirement on clock accuracy among all services currently in progress, or a QoS identifier of the first service. The first network device may store a correspondence between different service identifiers (or different QoS identifiers) and different numbers of cells. According to the corresponding relationship, the first network device may allocate an appropriate number of cells to the terminal. In addition, the terminal may also report the identifiers (e.g., frequency points) of one or more cells obtained by its own measurement to the first network device, for example, the identifiers are carried in the third indication information and reported to the first network device, and of course, the identifiers may also be carried in other indication information and reported to the first network device. In this way, the first network device may allocate an appropriate number of cells to the terminal according to the cell identifier reported by the terminal and the accuracy requirement of the terminal on the clock (or the identifier of the first service or the QoS identifier of the first service).

In some other embodiments, the first network device may allocate a suitable number of cells to the terminal (e.g., N cells are allocated to the terminal, where N is an integer greater than or equal to 2), and may also configure the signal strength threshold to the terminal. The terminal may perform clock synchronization with the cells allocated to the terminal by using the first network device, for example, when determining a frame boundary of a radio frame, the signal strength of the N cells may be monitored first, and if the signal strength of one or some cells in the N cells is lower than a configured signal strength threshold, the terminal may not use the cells to perform clock synchronization, for example, the cells may not be used to assist in determining a receiving time of the frame boundary of the radio frame, that is, the terminal may use M cells (M is less than or equal to N) to assist in determining the receiving time of the frame boundary of the radio frame. It should be noted that the signal strength threshold may be any one or more of Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and Received Signal Strength Indicator (RSSI). The signal strength threshold configured to the terminal by the first network device may be one or more. For example, the same signal strength threshold is configured for cells of different frequency bands. For another example, different signal strength thresholds are configured for cells of different frequency bands, e.g., a cell with a frequency band greater than 6GHz configures one signal strength threshold, and a cell with a frequency band less than 6GHz configures another signal strength threshold.

In some other embodiments, the first network device may also allocate several more cells than the terminal needs when allocating the cell to the terminal. Illustratively, the first network device determines, according to the third indication information, that the number of cells that need to be allocated to the terminal is X, but the first network device allocates N cells to the terminal (N is greater than or equal to X). For example, according to the accuracy requirement of the terminal on the clock, the first network device determines that the terminal can meet the requirement of the terminal only by using three cells, but the first network device allocates five cells to the terminal. When the terminal performs clock synchronization, for example, when determining the frame boundary of a radio frame, the five cells may be used to determine the frame boundary of the radio frame, or three cells with the strongest signals may be selected to determine the frame boundary of the radio frame according to the signal strength. Of course, the signal strengths of the three selected cells are all greater than the signal strength threshold.

In addition, it should be noted that, in this embodiment of the present application, the multiple (e.g., N) cells allocated by the first network device to the terminal may be used only for the terminal to perform frame boundary detection of the radio frame and/or determine a time value corresponding to a reception time of the radio frame, that is, only for performing clock synchronization, but not for other purposes, such as not being used for the terminal to perform carrier aggregation. Of course, the method and the device may also be used for the terminal to perform carrier aggregation, and the embodiment of the present application is not limited specifically here. And, the multiple cells allocated for the terminal may be physically co-sited or non-co-sited. It is only necessary to ensure that the frame boundaries of the radio frames of the multiple cells are aligned, i.e., the time when the signal is sent out is aligned. Of course, it is also possible that the difference between the frame boundaries of the radio frames of the plurality of cells is smaller than [2] × 64 × Tc, and the clock synchronization error between the terminal and the first network device can also be reduced.

It should be noted that, the above-mentioned process of determining the frame boundary of the radio frame (i.e. step 601 and step 602), the process of determining the time value corresponding to the transmission time of the frame boundary of the radio frame of the first cell (i.e. step 801 and step 802), and the above-mentioned process of determining the transmission delay between the terminal and the first network device are independent of each other and can be executed independently. That is, in a specific implementation, the TA method may be used to determine the transmission delay between the terminal and the first network device (e.g., acquire the TA, where the transmission delay is equal to one half of the TA), but the above steps 601 and 602 are used to determine the frame boundary of the radio frame. Alternatively, the TA method may be adopted to determine the transmission delay between the terminal and the first network device, but the time value corresponding to the transmission time of the frame boundary of the radio frame is determined in steps 801 and 802. The embodiments of the present application are not specifically limited herein. Of course, the process described in this embodiment may also be used to determine the transmission delay, determine the frame boundary of the radio frame, and determine the time value corresponding to the sending time of the frame boundary of the radio frame, so that the synchronization error of the clock between the terminal and the first network device may be smaller.

After the clock between the terminal and the first network device is synchronized, if the terminal needs to switch to the second network device, at present, the terminal needs to obtain the TA through the random access process, and then the TA and the second network device can be used for data transmission. In the embodiment of the application, the TA can be obtained without the need of the terminal to perform random access.

In some embodiments, further, as shown in fig. 11, the method may further include the steps of:

1101. the first network device sends a handover request to the second network device.

When the terminal resides in a cell (e.g., cell 1) of the first network device, the terminal may measure the signal quality of a cell adjacent to the cell 1, and may also report the measurement result to the first network device by carrying the measurement result in a measurement report. After receiving the measurement report sent by the terminal, the first network device may send a handover request to the second network device if it is determined that the signal quality of the second cell of the second network device indicated in the measurement report is good. The handover request is used to request a second network device to which the terminal is to be handed over to a second cell.

1102. And the second network equipment sends a switching response to the first network equipment, wherein the switching response comprises a third time value, and the third time value is used for indicating the sending time of the subframe boundary of the second cell of the second network equipment.

The second network device may return a handover response to the first network device after receiving the handover request sent by the first network device. In this embodiment, the handover response may carry a third time value indicating a transmission time of a subframe boundary of the second cell of the second network device. The second network device may inform the first network device of the precise time of the subframe boundary of the second cell (the target cell to which the terminal is to be handed over). The subframe boundary may be a start position or an end position of the subframe. For example, the subframe boundary is the starting position. The second network device may inform the first network device via the X2 interface that the time value for the starting position of the subframe of the second cell of the second network device is 306ms405us at 38 minutes 49 seconds 14 at 12 months 29 days 2018. The third time value may be an explicit (or plaintext) time value, which is readable by the first network device, or an implicit time value, which is carried in a container (container), which is unreadable by the first network device.

1103. And the first network equipment sends a switching command to the terminal, wherein the switching command comprises the third time value.

After receiving the third time value, the first network device may send the third time value to the terminal, where the third time value is carried in the handover command.

1104. And the terminal receives the third time value sent by the first network equipment.

1105. And after the terminal is switched to the second cell, acquiring a fourth time value, wherein the fourth time value is used for indicating the receiving time of the subframe boundary of the second cell.

1106. And the terminal determines the transmission delay between the terminal and the second network equipment according to the third time value and the fourth time value.

The terminal may perform downlink synchronization with the second network device after being handed over to the second cell of the second network device. During this time of the downlink synchronization, the clock internal to the terminal continues to run, and clock drift of the second network device and the terminal may not be taken into account during this time. The terminal may identify the subframe by detecting the synchronization sequence. In addition, the time value (i.e., the fourth time value) corresponding to the reception time at which the terminal can acquire the subframe boundary (e.g., the start position) of the identified subframe is 310ms705us of 38 minutes, 49 seconds, 310ms, 705 and us of 29 days and 14 days in 12 months in 2018, corresponding to the clock maintained by the terminal.

And, the terminal, according to the received third time value: in 2018, 12, 29, 14, 38 minutes, 49 seconds, 306ms, 405us, it can be inferred that the time values corresponding to the transmission time of the start positions of the other subframes of the second cell (the interval between the adjacent subframes is 1ms) are: 38 minutes 49 seconds 306ms405us at 14 of 29 months in 2018, 12 months in 2018, 14 days in 29 months in 38 minutes 49 seconds 307ms405us, 38 minutes 49 seconds 308ms405us at 14 days in 29 months in 12 months in 2018, 38 minutes 49 seconds 309ms405us at 14 days in 29 months in 12 months in 2018, 38 minutes 49 seconds 310ms405us at 14 days in 29 months in 12 months in 2018, and the like. The terminal selects the time value closest to the detected fourth time value from these time values, i.e., "310 ms405us for 38 minutes 49 seconds at 29 days 14 of 12 months in 2018". The terminal may consider the time value as the time value corresponding to the transmission time of the subframe boundary (start position) of the subframe detected by the terminal. It can be seen that the time value corresponding to the transmission time at the start position of the subframe is "38 minutes 49 seconds 310ms405us at 14 hours 29/12/29/2018", and the time value corresponding to the reception time at the start position of the subframe is "38 minutes 49 seconds 310ms705us at 14 hours 38 minutes 49/29/12/2018". Since the clocks of the first network device and the terminal are precisely synchronized, the terminal can determine that the downlink transmission delay between the terminal and the second network device is 300 us.

Or, the terminal may obtain possible transmission delays according to the time values, for example, if the terminal considers that the time value corresponding to the sending time is "310 ms405us of 38 minutes 49 seconds at 14 times of 12 months and 29 days in 2018", and it may be determined that the downlink transmission delay is 300us according to that the time value of the receiving time is "310 ms705us of 38 minutes 49 seconds at 14 times of 12 months and 29 days in 2018"; if the terminal considers that the time value corresponding to the sending moment is: "38 minutes 49 seconds 309ms405us at 14 hours of 29 th and 12 th in 2018", then it can be determined that the downlink transmission delay is 1300us according to the fact that the time value of the receiving time is "38 minutes 49 seconds 310ms705us at 14 hours of 29 th and 12 th in 2018"; if the terminal considers that the time value corresponding to the sending time is '308 ms405us in 38 minutes and 49 seconds at 14 days in 12 months and 29 months in 2018', the downlink transmission time delay can be determined to be 2300us according to the fact that the time value of the receiving time is '310 ms705us in 38 minutes and 49 seconds at 14 days in 12 months and 29 months in 2018'; if the terminal considers that the time value corresponding to the sending time is '307 ms405us in 38 minutes and 49 seconds at 14 days of 12 and 29 in 2018', the downlink transmission time delay can be determined to be 3300us according to the fact that the time value of the receiving time is '310 ms705us in 38 minutes and 49 seconds at 14 days of 12 and 29 in 2018'; if the terminal considers that the time value corresponding to the sending time is "306 ms405us in 38 minutes and 49 seconds at 14 days in 12 months and 29 months in 2018", the downlink transmission time delay is 4300us according to the fact that the time value of the receiving time is "310 ms705us in 38 minutes and 49 seconds at 14 days in 12 months and 29 months in 2018". In addition, the terminal may determine, according to other information, for example, knowing that the transmission delay between the terminal and the second network device cannot be 1300us, 2300us, 3300us, 4300us, a time value corresponding to the transmission delay 300us, that is, "38 minutes, 49 seconds, 310ms, 405 us", at 12, 29, in 2018, and 14, that is, a time value corresponding to the transmission time of the subframe boundary (start position) of the subframe detected by the terminal. Thereby determining that the transmission delay of the terminal and the second network device is 300 us.

1107. And the terminal transmits data according to the transmission delay between the terminal and the second network equipment.

After the terminal obtains the downlink transmission delay, the TA can be obtained by multiplying the downlink transmission delay by 2, so that when the terminal has data to transmit, the TA can be used for data transmission.

In other embodiments, further, as shown in fig. 12, the method may further include the steps of:

1201. the first network device sends a handover request to the second network device.

1202. The second network device sends a handover response to the first network device.

1203. The first network device sends a handover command to the terminal.

1204. After the terminal is switched to the second cell of the second network device, the terminal acquires a System Frame Number (SFN) of the second cell, and receives a fifth time value sent by the second network device, where the fifth time value is used to indicate a sending time of a frame boundary of a radio frame of the second cell.

As described in the embodiment shown in fig. 11, when the first network device determines that the signal quality of the second cell of the second network device is good, the terminal may be handed over to the second cell of the second network device. Unlike the embodiment shown in fig. 11, after the terminal is handed over to the second cell, the terminal may read the MIB message to obtain the SFN of the second cell, and receive a fifth time value sent by the second network device to indicate the transmission time of the frame boundary of the radio frame N of the second cell. If the second network device transmits a time service message to the terminal, the time value indicating the transmission time of the end position of the radio frame with "SFN ═ N" (i.e., the fifth time value) in the time service message is 302ms 405us at 38 minutes and 49 seconds at 14 days 14 and 14 minutes at 12 months 29 in 2018. The time service message may be sent by broadcasting or dedicated signaling, and is not limited in particular here.

1205. And the terminal acquires a sixth time value according to the SFN, wherein the sixth time value is used for indicating the receiving time of the frame boundary of the wireless frame of the second cell.

The terminal can determine the receiving time of the frame boundary (such as the end position) of the wireless frame N by detecting the synchronization sequence, and determine that the time value (i.e., the sixth time value) corresponding to the receiving time is "302 ms705us of 38 minutes, 49 seconds, 14 days, 29 months, 14 months, 12 months, 29 months, 2018" according to the clock maintained by the terminal.

1206. And the terminal determines the transmission delay between the terminal and the second network equipment according to the fifth time value and the sixth time value.

According to the fifth time value "38 minutes 49 seconds 302ms 405us at 14 of 29/12/29 in 2018" and the sixth time value "38 minutes 49 seconds 302ms705us at 14 of 29/12/29 in 2018", the terminal can determine that the downlink transmission delay between the terminal and the second network device is 300 us.

1207. And the terminal transmits data according to the transmission delay between the terminal and the second network equipment.

Thus, with the method shown in fig. 11 or fig. 12, after the terminal is handed over to the target cell (the second cell of the second network device), the terminal does not need to perform random access, and the TA can be obtained by the accurate time of the transmission time of the subframe boundary notified by the second network device or by reading the time service message of the target cell, so as to perform data transmission in the target cell.

The present embodiments also provide an apparatus for implementing any one of the above methods, for example, a clock synchronization apparatus is provided that includes a unit (or means) for implementing each step performed by a terminal in any one of the above methods.

For example: the clock synchronization apparatus may include: the obtaining unit, for example, performs step 502 in the above method to obtain the first information, step 504 obtains the first time value, step 601 obtains the receiving time of the frame boundary of the radio frame of M cells, step 1105 obtains the fourth time value, etc.

The determining unit, for example, executes step 505 of the method to determine a second time value corresponding to the receiving time of the frame boundary of the radio frame of the first cell according to the transmission delay and the first time value, step 802 determines the first time value according to the time values of M cells, step 1106 determines the transmission delay between the terminal and the second network device, and so on.

The clock synchronization apparatus may further include: the sending unit, for example, executes an operation of sending the first indication information to the first network device to indicate the first network device to resend the first information.

If step 602 is executed, the updating unit updates the receiving time of the frame boundary of the radio frame of the first cell according to the receiving time of the frame boundary of the radio frame of the M cells.

The receiving unit, for example, executes step 801 to receive time values indicating the transmission time of the frame boundary of the radio frame in M cells, step 1104 to receive a third time value, and so on.

The transmitting unit, for example, executes step 1107 to perform data transmission according to the transmission delay between the clock synchronization apparatus and the second network device.

For another example, another clock synchronization apparatus is also provided, which includes a unit (or means) for implementing each step performed by the network device in any one of the above methods. Such as the first network device, the second network device described above.

For example: the clock synchronization apparatus may include: the sending unit sends the first information to the terminal as executing step 501 in the method, step 503 sends a time value indicating a sending time of a frame boundary of the wireless frame to the terminal through a cell allocated to the terminal, steps 1101 and 1201 send a handover request to the second network device, steps 1103 and 1203 send a handover command to the terminal, and the like.

The clock synchronization apparatus may further include: and an acquisition unit for performing an operation of acquiring a distance between the terminal and the clock synchronization device. And a receiving unit for performing an operation of receiving the third indication information from the terminal. And an allocation unit, for example, performing an operation of allocating a suitable number of cells to the terminal.

It should be understood that the division of the units in the above apparatus is only a division of logical functions, and the actual implementation may be wholly or partially integrated into one physical entity or may be physically separated. And the units in the device can be realized in the form of software called by the processing element; or may be implemented entirely in hardware; part of the units can also be realized in the form of software called by a processing element, and part of the units can be realized in the form of hardware.

For example, each unit may be a processing element separately set up, or may be implemented by being integrated into a chip of the apparatus, or may be stored in a memory in the form of a program, and a function of the unit may be called and executed by a processing element of the apparatus. In addition, all or part of the units can be integrated together or can be independently realized. The processing element described herein may in turn be a processor, which may be an integrated circuit having signal processing capabilities. In the implementation process, the steps of the method or the units above may be implemented by integrated logic circuits of hardware in a processor element or in a form called by software through the processor element.

In one example, the units in any of the above apparatuses may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), or a combination of at least two of these integrated circuit forms.

As another example, when a unit in a device may be implemented in the form of a processing element scheduler, the processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of invoking programs. As another example, these units may be integrated together and implemented in the form of a system-on-a-chip (SOC).

The above unit for receiving is an interface circuit of the apparatus for receiving signals from other apparatuses. For example, when the device is implemented in the form of a chip, the receiving unit is an interface circuit for the chip to receive signals from other chips or devices. The above unit for transmitting is an interface circuit of the apparatus for transmitting a signal to other apparatuses. For example, when the device is implemented in the form of a chip, the transmitting unit is an interface circuit for the chip to transmit signals to other chips or devices.

Please refer to fig. 13, which is a schematic structural diagram of a network device according to an embodiment of the present application. Which may be the network device in the above embodiments, for implementing the operations of the network device in the above embodiments.

As shown in fig. 13, the network device includes: antenna 1301, radio frequency device 1302, baseband device 1303. The antenna 1301 is connected to the radio frequency device 1302. In the uplink direction, the rf device 1302 receives information transmitted by the terminal through the antenna 1301, and transmits the information transmitted by the terminal to the baseband device 1303 for processing. In the downlink direction, the baseband device 1303 processes the information of the terminal and sends the processed information to the rf device 1302, and the rf device 1302 processes the information of the terminal and sends the processed information to the terminal through the antenna 1301.

Baseband device 1303 may include one or more processing elements 1303-1, including, for example, a main CPU and other integrated circuits. In addition, the baseband device 1303 may further include a storage element 1303-2 and an interface 1303-3, where the storage element 1303-2 is used to store programs and data; the interface 1303-3 is used for exchanging information with the rf device 1302, and is, for example, a Common Public Radio Interface (CPRI). The above means for a network device may be located on the baseband means 1303, for example, the above means for a network device may be a chip on the baseband means 1303, the chip including at least one processing element and an interface circuit, wherein the processing element is configured to perform each step of any one of the methods performed by the above network device, and the interface circuit is configured to communicate with other devices. In one implementation, the unit of the network device for implementing the steps in the above method may be implemented in the form of a processing element scheduler, for example, an apparatus for the network device includes a processing element and a storage element, and the processing element calls a program stored in the storage element to execute the method executed by the network device in the above method embodiment. The memory elements may be memory elements on the same chip as the processing element, i.e. on-chip memory elements, or may be memory elements on a different chip than the processing element, i.e. off-chip memory elements.

In another implementation, the unit of the network device for implementing the steps of the above method may be configured as one or more processing elements, which are disposed on the baseband apparatus, where the processing elements may be integrated circuits, for example: one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits may be integrated together to form a chip.

The units of the network device implementing the steps of the above method may be integrated together and implemented in the form of a system-on-a-chip (SOC), for example, the baseband device 1303 includes the SOC chip for implementing the above method. At least one processing element and a storage element can be integrated in the chip, and the method executed by the network equipment is realized in the form that the processing element calls the stored program of the storage element; or, at least one integrated circuit may be integrated in the chip, for implementing the method executed by the above network device; alternatively, the above implementation modes may be combined, the functions of the partial units are implemented in the form of a processing element calling program, and the functions of the partial units are implemented in the form of an integrated circuit.

It is seen that the above apparatus for a network device may comprise at least one processing element and interface circuitry, wherein the at least one processing element is configured to perform the method performed by any one of the network devices provided by the above method embodiments. The processing element may: namely, calling the program stored in the storage element to execute part or all of the steps executed by the network equipment; it is also possible to: that is, some or all of the steps performed by the network device are performed by integrated logic circuitry of hardware in the processor element in combination with the instructions; of course, some or all of the steps performed by the above network device may also be performed in combination with the first manner and the second manner.

The processing elements herein, like those described above, may be a general purpose processor, such as a CPU, or one or more integrated circuits configured to implement the above methods, such as: one or more ASICs, or one or more microprocessors DSP, or one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms.

The storage element may be a memory or a combination of a plurality of storage elements.

Please refer to fig. 14, which is a schematic structural diagram of a terminal according to an embodiment of the present application. It may be the terminal in the above embodiment, for implementing the operation of the terminal in the above embodiment.

As shown in fig. 14, the terminal includes: antenna 1401, radio frequency part 1402, signal processing part 1403. An antenna 1401 is connected to the radio frequency section 1402. In the downlink direction, the radio frequency part 1402 receives information transmitted from the network device through the antenna 1401, and transmits the information transmitted from the network device to the signal processing part 1403 for processing. In the uplink direction, the signal processing part 1403 processes the information of the terminal and sends the information to the radio frequency part 1402, and the radio frequency part 1402 processes the information of the terminal and sends the information to the network device through the antenna 1401.

The signal processing section 1403 may include a modem subsystem for implementing processing of each communication protocol layer of data; the system also comprises a central processing subsystem used for realizing the processing of a terminal operating system and an application layer; in addition, other subsystems, such as a multimedia subsystem for implementing control of a terminal camera, a screen display, etc., peripheral subsystems for implementing connection with other devices, and the like may be included. The modem subsystem may be a separately provided chip. Alternatively, the above means for the terminal may be located at the modem subsystem.

The modem subsystem may include one or more processing elements 1403-1, including, for example, a master CPU and other integrated circuits.

The modem subsystem may also include a storage element 1403-2 and an interface circuit 1403-3. The storage element 1403-2 is used for storing data and programs, but programs for performing the methods performed by the terminal in the above methods may not be stored in this storage element 1403-2 but in a memory outside the modem subsystem, which is loaded for use when used. Interface circuit 1403-3 is used to communicate with other subsystems. The above apparatus for a terminal may be located in a modem subsystem, which may be implemented by a chip comprising at least one processing element for performing the steps of any of the methods performed by the above terminal and interface circuitry for communicating with other apparatus.

In one implementation, the unit of the terminal for implementing the steps of the above method may be implemented in the form of a processing element scheduler, for example, an apparatus for the terminal includes a processing element and a storage element, and the processing element calls a program stored in the storage element to execute the method executed by the terminal in the above method embodiment. The memory elements may be memory elements with the processing elements on the same chip, i.e. on-chip memory elements.

In another implementation, the program for performing the method performed by the terminal in the above method may be a memory element on a different chip than the processing element, i.e. an off-chip memory element. At this time, the processing element calls or loads a program from the off-chip storage element onto the on-chip storage element to call and execute the method executed by the terminal in the above method embodiment.

In yet another implementation, the unit of the terminal implementing the steps of the above method may be configured as one or more processing elements disposed on the modem subsystem, where the processing elements may be integrated circuits, for example: one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of these types of integrated circuits. These integrated circuits may be integrated together to form a chip.

The units of the terminal for realizing the steps of the method can be integrated together and realized in the form of SOC, and the SOC chip is used for realizing the method. At least one processing element and a storage element can be integrated in the chip, and the processing element calls the stored program of the storage element to realize the method executed by the terminal; or, at least one integrated circuit may be integrated in the chip for implementing the method executed by the above terminal; alternatively, the above implementation modes may be combined, the functions of the partial units are implemented in the form of a processing element calling program, and the functions of the partial units are implemented in the form of an integrated circuit.

It will be seen that the above apparatus for a terminal may comprise at least one processing element and interface circuitry, wherein the at least one processing element is adapted to perform any of the methods performed by the terminal provided by the above method embodiments. The processing element may: namely, calling the program stored in the storage element to execute part or all of the steps executed by the terminal; it is also possible to: that is, some or all of the steps performed by the terminal are performed by integrated logic circuits of hardware in the processor element in combination with instructions; of course, some or all of the steps performed by the terminal may be performed in combination with the first and second manners.

Through the above description of the embodiments, it is clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional modules is merely used as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device may be divided into different functional modules to complete all or part of the above described functions.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the modules or units is only one logical functional division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another device, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may be one physical unit or a plurality of physical units, that is, may be located in one place, or may be distributed in a plurality of different places. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially or partially contributed to by the prior art, or all or part of the technical solutions may be embodied in the form of a software product, where the software product is stored in a storage medium and includes several instructions to enable a device (which may be a single chip, a chip, or the like) or a processor (processor) to execute all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

The above description is only an embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions within the technical scope of the present disclosure should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of clock synchronization, comprising:

a terminal acquires first information, wherein the first information is used for determining the transmission delay between the terminal and first network equipment;

the terminal acquires a first time value, wherein the first time value is used for indicating the sending time of a frame boundary of a wireless frame of a first cell of the first network equipment;

and the terminal determines a second time value corresponding to the receiving time of the frame boundary of the wireless frame of the first cell according to the transmission delay and the first time value.

2. The method of claim 1, wherein the first information is information indicating the transmission delay.

3. The method of claim 1, wherein the first information is information indicating a distance between the terminal and the first network device;

the method further comprises the following steps:

and the terminal acquires the transmission delay according to the distance between the terminal and the first network equipment.

4. The method according to any one of claims 1-3, further comprising:

the terminal acquires the moving distance from the moment of acquiring the first information to the current moment;

and when the moving distance is greater than a distance threshold, the terminal sends first indication information to the first network equipment, wherein the first indication information is used for indicating the first network equipment to send the first information again.

5. The method according to any one of claims 1-4, further comprising:

the terminal acquires the receiving time of the frame boundaries of the wireless frames of M cells, the frame boundaries of the wireless frames of the M cells are aligned, the M cells comprise the first cell, and M is an integer greater than or equal to 2;

and the terminal updates the receiving time of the frame boundary of the wireless frame of the first cell according to the receiving time of the frame boundary of the wireless frame of the M cells.

6. The method according to any of claims 1-5, wherein the terminal obtaining the first time value comprises:

the terminal receives time values of M cells indicating the sending time of the frame boundaries of wireless frames, the frame boundaries of the wireless frames of the M cells are aligned, the M cells comprise the first cell, and M is an integer greater than or equal to 2;

and the terminal determines the first time value according to the time values of the M cells.

7. The method according to claim 6, wherein the time windows in which the terminal receives time values indicating the transmission time of the frame boundary of a radio frame are different for different cells in the M cells;

the method further comprises the following steps:

the terminal receives second indication information from the first network equipment, wherein the second indication information is used for indicating a time window of receiving a time value of a sending moment of a frame boundary of an indication wireless frame of a cell in each cell of N cells, and the N cells comprise the M cells;

the terminal receiving time values of the sending time of the frame boundary of the indication wireless frames of the M cells comprises the following steps:

and the terminal receives the time values of the M cells according to the time window indicated by the second indication information.

8. The method according to any one of claims 5-7, further comprising:

the terminal sends third indication information to the first network equipment, wherein the third indication information is used for the first network equipment to allocate a cell for the terminal, and the cell allocated for the terminal comprises the M cells;

the third indication information is the precision requirement of the terminal on the clock of the terminal; or, the third indication information is an identifier of a first service of the terminal or a QoS identifier of the first service, and a precision requirement of the first service of the terminal on the clock of the terminal is greater than a precision requirement of other services of the terminal on the clock of the terminal.

9. The method according to any one of claims 1-8, further comprising:

the terminal receives a third time value sent by the first network equipment, wherein the third time value is used for indicating the sending time of a subframe boundary of a second cell of second network equipment;

the terminal acquires a fourth time value after being switched to the second cell, wherein the fourth time value is used for indicating the receiving time of the subframe boundary of the second cell;

the terminal determines the transmission delay between the terminal and the second network equipment according to the third time value and the fourth time value;

and the terminal transmits data according to the transmission time delay between the terminal and the second network equipment.

10. The method according to any one of claims 1-8, further comprising:

the terminal acquires a System Frame Number (SFN) of a second cell after being switched to the second cell of second network equipment, and receives a fifth time value sent by the second network equipment, wherein the fifth time value is used for indicating the sending time of a frame boundary of a wireless frame of the second cell;

the terminal acquires a sixth time value according to the SFN, wherein the sixth time value is used for indicating the receiving time of the frame boundary of the wireless frame of the second cell;

the terminal determines the transmission delay between the terminal and the second network equipment according to the fifth time value and the sixth time value;

11. A clock synchronization apparatus, comprising:

a first obtaining unit, configured to obtain first information and a first time value, where the first information is used to determine a transmission delay between the clock synchronization apparatus and a first network device, and the first time value is used to indicate a sending time of a frame boundary of a radio frame of a first cell of the first network device;

a determining unit, configured to determine, according to the transmission delay and the first time value, a second time value corresponding to a receiving time of the frame boundary of the radio frame of the first cell.

12. The clock synchronization apparatus of claim 11, wherein the first information is information indicating the transmission delay.

13. The clock synchronization apparatus according to claim 11, wherein the first information is information indicating a distance between the clock synchronization apparatus and the first network device;

the first obtaining unit is further configured to obtain the transmission delay according to a distance between the clock synchronization apparatus and the first network device.

14. The clock synchronization apparatus of any one of claims 11-13, further comprising: a second acquiring unit and a transmitting unit;

the second obtaining unit is configured to obtain a moving distance from the time when the clock synchronization device obtains the first information to the current time;

the sending unit is configured to send first indication information to the first network device when the moving distance is greater than a distance threshold, where the first indication information is used to indicate the first network device to resend the first information.

15. The clock synchronization apparatus of any one of claims 11-14, further comprising: an update unit;

the first obtaining unit is further configured to obtain receiving time of the frame boundaries of radio frames of M cells, where the frame boundaries of the radio frames of M cells are aligned, the M cells include the first cell, and M is an integer greater than or equal to 2;

the updating unit is configured to update the receiving time of the frame boundary of the radio frame of the first cell according to the receiving time of the frame boundary of the radio frame of the M cells.

16. The clock synchronization apparatus of any one of claims 11-15, further comprising: a receiving unit;

the receiving unit is configured to receive time values of M cells indicating transmission timings of the frame boundaries of radio frames, the frame boundaries of the radio frames of the M cells being aligned, the M cells including the first cell, and M being an integer greater than or equal to 2;

the first obtaining unit is specifically configured to determine the first time value according to the time values of the M cells.

17. The clock synchronization apparatus of claim 16, wherein the time windows for the clock synchronization apparatus to receive time values indicating the transmission time of the frame boundary of a radio frame are different for different cells in the M cells;

the receiving unit is further configured to receive second indication information from the first network device, where the second indication information is used to indicate a time window for receiving a time value of a transmission time of the frame boundary of the radio frame of the cell in each of N cells, where the N cells include the M cells;

the receiving unit is specifically configured to receive the time values of the M cells according to the time window indicated by the second indication information.

18. The clock synchronization apparatus of any one of claims 15-17, further comprising: a transmitting unit;

the sending unit is configured to send third indication information to the first network device, where the third indication information is used for the first network device to allocate a cell to the clock synchronization apparatus, and the cell allocated to the clock synchronization apparatus includes the M cells;

the third indication information is the precision requirement of the clock synchronization device on the clock of the clock synchronization device; or, the third indication information is an identifier of a first service of the clock synchronization apparatus or a QoS identifier of the first service, and a precision requirement of the first service of the clock synchronization apparatus on the clock of the clock synchronization apparatus is greater than a precision requirement of other services of the clock synchronization apparatus on the clock of the clock synchronization apparatus.

19. The clock synchronization apparatus of any one of claims 11-18, further comprising: a receiving unit and a transmitting unit;

the receiving unit is configured to receive a third time value sent by the first network device, where the third time value is used to indicate a sending time of a subframe boundary of a second cell of a second network device;

the second obtaining unit is further configured to obtain a fourth time value after the handover to the second cell is performed, where the fourth time value is used to indicate a receiving time of a subframe boundary of the second cell;

the determining unit is further configured to determine, according to the third time value and the fourth time value, a transmission delay between the clock synchronization apparatus and the second network device;

and the transmission unit is used for transmitting data according to the transmission time delay of the clock synchronization device and the second network equipment.

20. The clock synchronization apparatus of any one of claims 11-18, further comprising: a transmission unit;

the first obtaining unit is further configured to obtain a System Frame Number (SFN) of a second cell after the handover to the second cell of a second network device, and receive a fifth time value sent by the second network device, where the fifth time value is used to indicate a sending time of a frame boundary of a wireless frame of the second cell;

the second obtaining unit is further configured to obtain a sixth time value according to the SFN, where the sixth time value is used to indicate a receiving time of the frame boundary of the radio frame of the second cell;

the determining unit is further configured to determine, according to the fifth time value and the sixth time value, a transmission delay between the clock synchronization apparatus and the second network device;

21. A clock synchronization apparatus, comprising: a processor and interface circuitry, the processor to communicate with a network device through the interface circuitry and to perform the method of any of claims 1 to 10.

22. A clock synchronization apparatus comprising a processor coupled to a memory, the processor calling a program stored in the memory to perform the method of any of claims 1 to 10.

23. A terminal, characterized in that it comprises a clock synchronization device according to any one of claims 11 to 20.

24. A computer-readable storage medium, comprising: computer software instructions;

the computer software instructions, when run in a clock synchronization device or a chip built into a clock synchronization device, cause the clock synchronization device to perform the method of any of claims 1 to 10.