Synchronization method, device and terminal equipment

Abstract

The present invention provides a synchronization method, device and terminal equipment, which relate to the field of communication technology. The synchronization method is executed by a first terminal device, including: sending a pilot signal and a first synchronization control signaling to a second terminal device; wherein the first synchronization control signaling is used to indicate: the synchronization level of the first terminal device; the frame number and subframe number for synchronization. The above scheme, by sending the first synchronization control signaling and the pilot signal to the second terminal device, is used to indicate the synchronization level and the frame number and subframe number for synchronization to other devices, thereby achieving synchronization between terminals and improving the efficiency of synchronization.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a synchronization method, device and terminal equipment. Background Art

[0002] In the process of implementing this application, the inventors found that there are at least the following problems in the prior art:

[0003] When a vehicle is in a complex environment such as an urban canyon, overpass, viaduct, underground parking lot, tunnel, etc., it may not be able to receive satellite signals and cannot synchronize time through satellite signals. The internal clock accuracy of the Internet of Vehicles equipment is low and cannot meet the requirements of high-precision time synchronization for a long time. In the prior art, there is no solution for direct link synchronization signals that meets industry standards and can be implemented. At the same time, under the distributed architecture of the Internet of Vehicles, synchronization and coordination between a large number of terminals is difficult. Summary of the invention

[0004] Embodiments of the present invention provide a synchronization method, apparatus, and terminal device to solve the problem of difficulty in synchronization and coordination among a large number of terminals under the distributed architecture of the existing Internet of Vehicles.

[0005] In order to solve the above technical problem, an embodiment of the present invention provides a synchronization method, which is executed by a first terminal device and includes:

[0006] Sending a pilot signal and a first synchronization control signaling to a second terminal device;

[0007] The first synchronization control signaling is used to indicate:

[0008] a synchronization level of the first terminal device;

[0009] The frame number and subframe number for synchronization.

[0010] Optionally, the sending the pilot signal and the first synchronization control signaling to the second terminal device includes:

[0011] Sending the first synchronization control signaling to the second terminal device via a direct link control channel PSCCH; or

[0012] Sending the first synchronization control signaling to the second terminal device via the PSCCH and the direct link shared channel PSSCH;

[0013] The pilot signal is a demodulation reference signal DMRS.

[0014] Optionally, the sending the first synchronization control signaling to the second terminal device through the PSCCH and the direct link shared channel PSSCH includes:

[0015] Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and

[0016] Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH;

[0017] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0018] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0019] Wherein, N is less than or equal to 7.

[0020] Alternatively, according to the formula:

[0021] Indicating whether the PSCCH carries the first synchronization control signaling;

[0022] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0023] Optionally, if the synchronization levels indicated by the first synchronization control signaling sent by the first terminal device at different times are different, the first terminal device sends the second part of the first synchronization control signaling indicating different synchronization levels on the PSSCH using frequency division multiplexing FDM or time division multiplexing TDM.

[0024] Optionally, the synchronization method further includes:

[0025] Sending a second synchronization control signaling to the second terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe;

[0026] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0027] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0028] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0029] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0030] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0031] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0032] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the reserved subframe occupancy mode for the first terminal device to send the second synchronization control signaling of different synchronization levels includes:

[0033] When the first terminal device is at a first synchronization level, the first terminal device sends a second synchronization control signaling on a second reserved subframe;

[0034] When the first terminal device is at a second synchronization level, the first terminal device sends a second synchronization control signaling on a first reserved subframe;

[0035] When the first terminal device is at the third synchronization level, the first terminal device sends a second synchronization control signaling on a first target reserved subframe, where the first target reserved subframe is the one with lower receiving power between the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0036] When the first terminal device is at the fourth synchronization level, the first terminal device randomly selects a subframe based on an internal clock to send a second synchronization control signaling.

[0037] Optionally, the synchronization level of the first terminal device includes one of the following:

[0038] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0039] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0040] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0041] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0042] The priority of the synchronization levels is in the order of high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0043] The embodiment of the present invention further provides a synchronization method, which is executed by a second terminal device and includes:

[0044] Determining whether a first signal is received, the first signal comprising: a pilot signal and a first synchronization control signaling sent by at least one first terminal device;

[0045] If the first signal is received, determining a synchronization source of the second terminal device;

[0046] determining a synchronization level of the second terminal device according to a synchronization source of the second terminal device;

[0047] The first synchronization control signaling is used to indicate:

[0048] a synchronization level of the first terminal device;

[0049] The frame number and subframe number for synchronization.

[0050] Optionally, the pilot signal and the first synchronization control signaling sent by the at least one first terminal device include:

[0051] A first synchronization control signaling sent by at least one first terminal device via a direct link control channel PSCCH; or

[0052] A first synchronization control signaling sent by at least one first terminal device via the PSCCH and the direct link shared channel PSSCH;

[0053] The pilot signal is a demodulation reference signal DMRS.

[0054] Optionally, in the case where the at least one first terminal device sends the first synchronization control signaling through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries the first part of the first synchronization control signaling, and the PSSCH carries the second part of the first synchronization control signaling;

[0055] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0056] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0057] Wherein, N is less than or equal to 7.

[0058] Alternatively, according to the formula:

[0059] Indicating whether the PSCCH carries the first synchronization control signaling;

[0060] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0061] Optionally, the second part of the first synchronization control signaling of the first terminal devices of different synchronization levels is sent on the PSSCH in a frequency division multiplexing FDM or time division multiplexing TDM manner.

[0062] Optionally, if the first signal is received, determining a synchronization source of the second terminal device includes:

[0063] The first terminal device corresponding to a first synchronization control signaling with the highest synchronization level in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

[0064] Optionally, the first signal further includes: a second synchronization control signaling and / or a global navigation satellite system GNSS signal sent by at least one first terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe;

[0065] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0066] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0067] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0068] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0069] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0070] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0071] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the manner in which the second terminal device receives the second synchronization control signaling of different synchronization levels includes:

[0072] When the first terminal device is at a first synchronization level, the second terminal device receives a second synchronization control signaling on a second reserved subframe;

[0073] When the first terminal device is at a second synchronization level, the second terminal device receives a second synchronization control signaling on a first reserved subframe;

[0074] When the first terminal device is at the third synchronization level, the second terminal device receives the second synchronization control signaling on the first target reserved subframe, where the first target reserved subframe is a reserved subframe with low receiving power among the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0075] When the first terminal device is at the fourth synchronization level, the second terminal device receives a second synchronization control signaling on a second target reserved subframe, where the second target reserved subframe is a subframe randomly selected by the first terminal device based on an internal clock.

[0076] Optionally, if the first signal is received, determining a synchronization source of the second terminal device includes:

[0077] In the case where the first signal includes a GNSS signal, using the GNSS signal as a synchronization source for the second terminal device;

[0078] When the first signal does not include a GNSS signal, the first terminal device corresponding to the highest synchronization level in the first signaling is determined as the synchronization source of the second terminal device, and the first signaling is the first synchronization control signaling, or the first signaling is the first synchronization control signaling and the second synchronization control signaling.

[0079] Optionally, the synchronization level of the first terminal device includes one of the following:

[0080] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0081] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0082] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0083] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0084] The priority of the synchronization levels is in the order from high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0085] An embodiment of the present invention further provides a terminal device, comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program implements the steps of the above-mentioned synchronization method when executed by the processor.

[0086] The embodiment of the present invention further provides a synchronization device, applied to a first terminal device, comprising:

[0087] A sending module, used for sending a pilot signal and a first synchronization control signaling to a second terminal device;

[0088] The first synchronization control signaling is used to indicate:

[0089] a synchronization level of the first terminal device;

[0090] The frame number and subframe number for synchronization.

[0091] The embodiment of the present invention further provides a synchronization device, which is applied to a second terminal device, including:

[0092] A determination module, configured to determine whether a first signal is received, wherein the first signal includes: a pilot signal and a first synchronization control signaling sent by at least one first terminal device;

[0093] A first determination module, configured to determine a synchronization source of the second terminal device if the first signal is received;

[0094] A second determining module, configured to determine a synchronization level of the second terminal device according to a synchronization source of the second terminal device;

[0095] The first synchronization control signaling is used to indicate:

[0096] a synchronization level of the first terminal device;

[0097] The frame number and subframe number for synchronization.

[0098] An embodiment of the present invention further provides a readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned synchronization method are implemented.

[0099] The beneficial effects of the present invention are:

[0100] The above scheme sends the first synchronization control signaling and the pilot signal to the second terminal device, thereby indicating the synchronization level and the frame number and subframe number to be synchronized to other devices, thereby achieving synchronization between terminals and improving the synchronization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 A schematic diagram showing a flow chart of a synchronization method according to an embodiment of the present invention;

[0102] Figure 2 A schematic diagram showing a time division multiplexing message sending method;

[0103] Figure 3 A schematic diagram showing a method of sending messages using frequency division multiplexing;

[0104] Figure 4 A second flowchart diagram showing a synchronization method according to an embodiment of the present invention;

[0105] Figure 5 A schematic diagram showing a detailed flow chart of an embodiment of the present invention;

[0106] Figure 6 An architecture diagram showing application scenario 1 of an embodiment of the present invention;

[0107] Figure 7 An architecture diagram showing application scenario 2 of an embodiment of the present invention;

[0108] Figure 8 One of the module schematic diagrams showing the synchronization device according to an embodiment of the present invention;

[0109] Fig. 9 A structural diagram showing a terminal device according to an embodiment of the present invention;

[0110] Fig.10 The second schematic diagram of the module of the synchronization device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0111] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0112] First, some concepts related to the embodiments of the present invention are described as follows.

[0113] High-precision time synchronization is one of the key technologies of the Internet of Vehicles. It is not only related to the safety of vehicles during driving, but also affects the safety of other traffic participants and the development of various Internet of Vehicles applications. The main synchronization sources of Internet of Vehicles devices include: Global Navigation Satellite System (GNSS), gNB / eNB, other Internet of Vehicles devices and the internal clock of the device. However, when the vehicle is in a complex environment such as an urban canyon, an overpass, an elevated bridge, an underground parking lot, a tunnel, etc., it may not be able to receive satellite signals and cannot perform time synchronization through satellite signals. The internal clock accuracy of Internet of Vehicles devices is low and cannot meet the requirements of high-precision time synchronization for a long time. Therefore, unsynchronized Internet of Vehicles devices need to obtain time synchronization signals through other synchronized Internet of Vehicles devices. In addition, the current Internet of Vehicles mainly uses Orthogonal Frequency Division Multiplexing (OFDM) modulation technology for communication. OFDM systems generally require accurate time synchronization to maintain orthogonality between carriers.

[0114] There are two main synchronization signals in the synchronization scheme defined by 3GPP: 1) Sidelink Synchronization Signal (SLSS), which is used for synchronization in time and frequency; 2) Master Information Block SL (MIB-SL), which provides other information. For SLSS, there are Primary Sidelink Synchronization Signal (PSSS) and Secondary Sidelink Synchronization Signal (SSSS).

[0115] MIB-SL is transmitted through the Physical Sidelink Broadcast Channel (PSBCH) and carries the following information: the inCoverage flag indicates whether the synchronization signal transmitting device is within the coverage of the cell; directFrameNumber and directSubFrameNumber correspond to the frame number and subframe number when connected to the coverage. When the user equipment (UE, also known as the terminal) sends SLSS and MIB-SL, it must select parameters and determine the corresponding subframe. In order to facilitate the processing of subframes used for service transmission in the resource pool, the physical subframes determined by the system frame number (SFN) are mapped into logical subframes in the form of a synchronization bitmap. The following three types of subframes need to be excluded from the physical subframes to obtain the logical subframes: 1) All downlink (DL) subframes and special subframes when the PC5 port and the Uu port share a time division duplex (TDD) carrier; 2) Synchronous subframes used to send SLSS and PSBCH, and the synchronization period is agreed to be 160ms; 3) Reserved subframes.

[0116] In the SFN cycle (10240ms), after excluding 1) and 2), the remaining subframes are arranged in ascending order and recorded as Where N slss N is the number of subframes configured as SLSS resources in 10240 subframes. dssf It is the total number of downlink subframes and special subframes in 10240 subframes when the direct link transmission occurs in a time division duplexing (TDD) cellular cell. According to the bitmap mapping, the subframes in the SFN cycle that cannot be divided by the bitmap are called reserved subframes. The number of reserved subframes is calculated as follows:

[0117] N reserved =(10240-N slss -N dssf )mod L bitmap ,

[0118] Among them, N reserved is the number of reserved subframes; L bitmap Bitmap length configured for higher layers.

[0119] Then, the reserved subframes are evenly distributed to the SFN as follows:

[0120]

[0121] where m=0,...,N reserved -1.

[0122] By excluding the above three types of subframes, the remaining subframes in the SFN / DFN cycle can be used to send vehicle-to-everything (V2X) services. The resource pool configuration uses a bitmap to indicate the logical subframes through the time domain indication method. The protocol stipulates that the bitmap length can be any value among 16, 20 and 100.

[0123] The prior art stipulates that the bitmap length is 100, the number of reserved subframes is 40, and the period is 256ms. At the same time, the industry standard points out that the roadside equipment can send direct link synchronization signals in subframes that are not configured for V2X message transmission based on its own capabilities, and these subframes at least include reserved subframes.

[0124] In the prior art, there is no solution for direct link synchronization signals that complies with industry standards and can be implemented; at the same time, under the distributed architecture of the Internet of Vehicles, synchronization and coordination between a large number of terminals is difficult.

[0125] In view of the above problems, the present invention provides a synchronization method, device and terminal equipment.

[0126] like Figure 1 As shown, the synchronization method of the embodiment of the present invention is executed by the first terminal device, including:

[0127] Step 11, sending a pilot signal and a first synchronization control signaling to a second terminal device;

[0128] The first synchronization control signaling is used to indicate:

[0129] a synchronization level of the first terminal device;

[0130] The frame number and subframe number for synchronization.

[0131] It should be noted that the first terminal device usually refers to a roadside device.

[0132] It should also be noted that the synchronization control signaling mentioned in the embodiment of the present invention refers to the synchronization message, and the first synchronization control signaling can be considered as the synchronization message 1.

[0133] It should be further explained that the following synchronization levels are defined in the embodiment of the present invention:

[0134] A11, first synchronization level (i.e., synchronization level 1), indicating that the synchronization source of the first terminal device is a global navigation satellite system (GNSS) signal;

[0135] A12, second synchronization level (i.e., synchronization level 2), indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0136] A13, third synchronization level (i.e., synchronization level 3), indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0137] A14, fourth synchronization level (i.e., synchronization level 4), indicating that the first terminal device cannot receive a synchronization signal;

[0138] The priority of the synchronization levels is in the order of high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0139] It should also be noted that in the embodiment of the present invention, the GNSS signal is defined as synchronization level 0.

[0140] The first terminal device indicates one of the above synchronization levels through the first synchronization control signaling.

[0141] Further, the sending of the pilot signal and the first synchronization control signaling to the second terminal device in the embodiment of the present invention includes one of the following:

[0142] A21. Sending the first synchronization control signaling to the second terminal device through a direct link control channel (PSCCH);

[0143] It should be noted that, in this case, the first terminal device sends the first synchronization control signaling via the PSCCH.

[0144] It should be noted that the pilot signal is a demodulation reference signal (DMRS). It should be noted that for LTE-V2X and NR-V2X systems, when PSCCH is transmitted, a DMRS signal is sent at the same time, which can be used for PSCCH channel detection on the receiving side.

[0145] A22, sending the first synchronization control signaling to the second terminal device through the PSCCH and the direct link shared channel (PSSCH);

[0146] It should be noted that the pilot signal is DMRS. It should be pointed out that for LTE-V2X system and NR-V2X system, when PSCCH is transmitted, DMRS signal is sent at the same time, which can be used for PSCCH channel detection on the receiving side; when PSSCH is transmitted, DMRS signal is sent at the same time, which can be used for PSSCH channel detection on the receiving side.

[0147] It should be noted that, in this case, the first terminal device sends the first synchronization control signaling through the PSCCH and the PSSCH. Specifically, in this case, the specific implementation method of step 11 is:

[0148] Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and

[0149] Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH;

[0150] Specifically, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and the subframe number for synchronization.

[0151] Specifically, since the existing direct link control information (SCI) adopts SCI format 1, there are currently at least 7 bits left as filling bits (i.e., reserved bits). When the first part is sent, the first part is carried by N bits in the reserved bits of the SCI in the PSCCH (i.e., a i , a i+1 , ...a i+N-1 );

[0152] Wherein, N is less than or equal to 7.

[0153] It should be noted that, usually, the N bits refer to the last N bits in the reserved bits. For example, the last 4 bits in the reserved bits can be used to send the first part.

[0154] Further, in the embodiment of the present invention, Formula 1 is used to indicate whether the PSCCH carries the first synchronization control signaling. Specifically, Formula 1 is:

[0155]

[0156] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0157] It should be further explained that if the synchronization levels indicated by the first synchronization control signaling sent by the first terminal device at different times are different, the first terminal device uses frequency division multiplexing (FDM) or time division multiplexing (TDM) to send the second part of the first synchronization control signaling indicating different synchronization levels on the PSSCH.

[0158] Specifically, for the TDM method, such as Figure 2 As shown, the second part of the first synchronization control signaling of the first synchronization level and the second synchronization level is sent in the same frequency band of PSSCH, occupying 30 physical resource blocks (PRBs), and the second part of the first synchronization control signaling of the first synchronization level and the second synchronization level is sent in different subframes in the time domain of PSSCH. For the FDM method, such as Figure 3 As shown, the second part of the first synchronization control signaling of different synchronization levels is sent in the same subframe and different frequency bands. For example, the second part of the first synchronization control signaling of the first synchronization level is sent in PRBs of 0-20, the second part of the first synchronization control signaling of the second synchronization level is sent in PRBs of 40-60, and the second part of the first synchronization control signaling of the third synchronization level is sent in PRBs of 80-100. It should be noted that when the first terminal device is at the fourth synchronization level, it does not send the first synchronization control signaling.

[0159] It should be further explained that, based on the above, the embodiment of the present invention further includes:

[0160] Sending a second synchronization control signaling to the second terminal device on a direct link broadcast channel (PSBCH) sent through a reserved subframe;

[0161] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0162] It should be noted that the synchronization control signaling mentioned in the embodiment of the present invention refers to the synchronization message, and the second synchronization control signaling can be considered as the synchronization message 2.

[0163] It should also be noted that the synchronization level of the first terminal device in the first synchronization control signaling and the second synchronization control signaling sent by the same first terminal device is the same.

[0164] It should be further explained that, since the second synchronization control signaling does not explicitly carry the synchronization level of the first terminal device, when the second terminal device obtains the second synchronization control signaling, it is necessary to determine the synchronization level according to the correspondence between the synchronization level, the indication information, and the direct link synchronization signal index (SLSS ID). Specifically, the correspondence between the synchronization level, the indication information, and the direct link synchronization signal index includes at least one of the following:

[0165] A31, when the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0166] It should be noted that when the indication information is 1, it indicates that the first terminal device is within the GNSS coverage.

[0167] A32, when the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0168] It should be noted that when the indication information is 0, it indicates that the first terminal device is not within the GNSS coverage range (ie, the first terminal device is outside the GNSS coverage range).

[0169] A33, when the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0170] For example, the preset value is 168.

[0171] A34. When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0172] It should be further explained that the bitmap length is specified as 100 in the prior art, and the number of reserved subframes is N. rsf =40, with a period of 256ms. In the embodiment of the present invention, the two reserved subframe transmission periods are set as one direct link synchronization signal transmission period, i.e., 512ms. That is to say, the direct link synchronization signal transmission period in the PSBCH includes the first reserved subframe and the second reserved subframe. The number of the first reserved subframe is: N rsf1 =1,3,5,...,N rsf -1, the corresponding second reserved subframe number is N rsf2 =2,4,6,...,N rsf , which will be numbered N in this application rsf1 The reserved subframe is defined as an odd reserved subframe, and the subframe numbered N rsf2The reserved subframe is defined as an even reserved subframe, then the reserved subframe occupancy mode for the first terminal device to send the second synchronization control signaling of different synchronization levels includes:

[0173] A41. When the first terminal device is at the first synchronization level, the first terminal device sends a second synchronization control signaling in a second reserved subframe;

[0174] That is, when the first terminal device is at the first synchronization level, it sends the second synchronization control signaling on the even reserved subframe.

[0175] A42. When the first terminal device is at a second synchronization level, the first terminal device sends a second synchronization control signaling on a first reserved subframe;

[0176] That is to say, when the first terminal device is at the second synchronization level, it sends the second synchronization control signaling on the odd reserved subframe.

[0177] A43. When the first terminal device is at the third synchronization level, the first terminal device sends a second synchronization control signaling on the first target reserved subframe;

[0178] Specifically, the first target reserved subframe is the one with lower receiving power between the first reserved subframe and the second reserved subframe detected by the first terminal device; for example, the first terminal device monitors the receiving power of the even reserved subframe and the odd reserved subframe, and when the receiving power of the even reserved subframe is lower than the receiving power of the odd reserved subframe, the first terminal device sends a second synchronization control signaling on the even reserved subframe.

[0179] A44. When the first terminal device is at the fourth synchronization level, the first terminal device randomly selects a subframe based on an internal clock to send a second synchronization control signaling;

[0180] It should be noted that when the first terminal device is at the fourth synchronization level, when it chooses to send the second synchronization control signaling, it will randomly select subframes in the even reserved subframes and odd reserved subframes according to the internal clock to perform the second synchronization control signaling; it should also be noted that when the first terminal device is at the fourth synchronization level, the first terminal device may also choose not to send the second synchronization control signaling. Specifically, whether the first terminal device sends the second synchronization control signaling depends on the system implementation.

[0181] Corresponding to the above sending method, such as Figure 4 As shown, the synchronization method of the embodiment of the present invention is executed by the second terminal device, including:

[0182] Step 41, determining whether a first signal is received, wherein the first signal includes: a pilot signal and a first synchronization control signaling sent by at least one first terminal device;

[0183] Step 42, if the first signal is received, determining the synchronization source of the second terminal device;

[0184] Step 43, determining a synchronization level of the second terminal device according to the synchronization source of the second terminal device;

[0185] The first synchronization control signaling is used to indicate:

[0186] a synchronization level of the first terminal device;

[0187] The frame number and subframe number for synchronization.

[0188] It should be noted that the definition of the synchronization level in this embodiment is the same as that in the previous embodiment, and specifically includes:

[0189] B11, first synchronization level, indicating that the synchronization source of the first terminal device is a global navigation satellite system (GNSS) signal;

[0190] B12, second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0191] B13, third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0192] B14, fourth synchronization level, indicating that the first terminal device cannot receive a synchronization signal;

[0193] The priority of the synchronization levels is in the order from high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0194] A first synchronization control signaling received by the second terminal device indicates one of the above synchronization levels.

[0195] Further, the pilot signal and the first synchronization control signaling sent by the at least one first terminal device include:

[0196] A first synchronization control signaling sent by at least one first terminal device via a direct link control channel PSCCH; or

[0197] A first synchronization control signaling sent by at least one first terminal device via the PSCCH and the direct link shared channel PSSCH;

[0198] The pilot signal is a demodulation reference signal DMRS.

[0199] It should be noted that, in the case where the at least one first terminal device sends the first synchronization control signaling through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries the first part of the first synchronization control signaling, and the PSSCH carries the second part of the first synchronization control signaling;

[0200] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0201] Specifically, the first part is carried by N bits in the reserved bits of the direct link control information SCI in the PSCCH;

[0202] Wherein, N is less than or equal to 7.

[0203] It should be noted that, in the embodiment of the present invention, according to the formula:

[0204] Indicating whether the PSCCH carries the first synchronization control signaling;

[0205] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0206] It should also be noted that the second part of the first synchronization control signaling of the first terminal devices of different synchronization levels is sent on the PSSCH using frequency division multiplexing FDM or time division multiplexing TDM.

[0207] Specifically, if the first signal is received, determining the synchronization source of the second terminal device includes:

[0208] The first terminal device corresponding to a first synchronization control signaling with the highest synchronization level in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

[0209] It should be noted that when the second terminal device only receives the first synchronization control signaling sent by different first terminal devices, the first terminal device with the highest synchronization level indicated in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

[0210] Further, the first signal further includes: a second synchronization control signaling and / or a global navigation satellite system (GNSS) signal sent by at least one first terminal device on a direct link broadcast channel (PSBCH) sent through a reserved subframe;

[0211] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0212] In this case, if the first signal is received, determining the synchronization source of the second terminal device includes:

[0213] In the case where the first signal includes a GNSS signal, using the GNSS signal as a synchronization source for the second terminal device;

[0214] When the first signal does not include a GNSS signal, the first terminal device corresponding to the highest synchronization level in the first signaling is determined as the synchronization source of the second terminal device, and the first signaling is the first synchronization control signaling, or the first signaling is the first synchronization control signaling and the second synchronization control signaling.

[0215] That is to say, as long as the second terminal device can receive the GNSS signal, the GNSS signal will be used as the synchronization source of the second terminal device; when the second terminal device can simultaneously receive the first synchronization control signaling and the second synchronization control signaling sent by different first terminal devices, whichever synchronization level is the highest in the synchronization control signaling, the first terminal device with the corresponding highest synchronization level will be used as its synchronization source.

[0216] Further, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0217] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0218] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0219] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0220] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0221] Specifically, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the manner in which the second terminal device receives the second synchronization control signaling of different synchronization levels includes:

[0222] When the first terminal device is at a first synchronization level, the second terminal device receives a second synchronization control signaling on a second reserved subframe;

[0223] When the first terminal device is at a second synchronization level, the second terminal device receives a second synchronization control signaling on a first reserved subframe;

[0224] When the first terminal device is at the third synchronization level, the second terminal device receives the second synchronization control signaling on the first target reserved subframe, where the first target reserved subframe is a reserved subframe with low receiving power among the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0225] When the first terminal device is at the fourth synchronization level, the second terminal device receives a second synchronization control signaling on a second target reserved subframe, where the second target reserved subframe is a subframe randomly selected by the first terminal device based on an internal clock.

[0226] It should be noted that the second terminal device of the embodiment of the present invention may be an on-board unit (OBU), a vulnerable road user (Vulnerable Roas Users, VRU) or a roadside unit (RSU). It should be particularly noted that when the second terminal device is an RSU, after synchronization according to the synchronization source, the synchronization control signaling will be sent using the method of the above embodiment.

[0227] In combination with the above embodiments, the synchronization process involved in the present invention is described in detail as follows.

[0228] like Figure 5 As shown, the detailed process of time synchronization in the embodiment of the present invention is as follows:

[0229] After the local device is powered on, it first detects whether it can receive GNSS signals. If it can receive GNSS signals, the local device updates the local clock according to the GNSS signals and enters the synchronization state. The synchronization level is the first synchronization level. The indication information (i.e. inCoverage) of whether it is within the coverage of GNSS is 1, indicating that the local device is within the coverage of GNSS, and the SLSS ID is 0. The local device that enters the synchronization state sends synchronization control signaling (i.e. synchronization messages) through PSCCH&PSSCH and PSBCH respectively.

[0230] If the local device does not receive the GNSS signal, the local device enters the out-of-sync state and receives the synchronization messages sent by other devices; if the local device can receive the synchronization messages sent by other devices through PSCCH&PSSCH or PSBCH, and the signal power is greater than the threshold setting value, the local device synchronizes with the synchronization message with the highest synchronization level, and the local device enters the synchronization state. The local device sends synchronization messages through PSCCH&PSSCH and PSBCH respectively; if the synchronization source of the local device is the first synchronization level, the synchronization level of the local device is the second synchronization level, the inCoverage flag is 0, indicating that the local device is not within the coverage of the GNSS, and the SLSS ID is 0; if the synchronization source of the local device is the second synchronization level or the third synchronization level, the synchronization level of the local device is the third synchronization level, the inCoverage flag is 0, indicating that the local device is not within the coverage of the GNSS, and the SLSS ID is 168.

[0231] If the local device does not receive the GNSS signal, the local device enters the out-of-sync state and receives the synchronization message sent by other devices; if the local device does not receive the synchronization message sent by other devices through PSCCH and PSSCH, and does not receive the synchronization message sent by other devices through PSBCH, the local device enters the out-of-sync state, the inCoverage flag is 0, indicating that the local device is not within the coverage of GNSS, and the SLSS ID is a random number greater than 168, indicating that the local device has no synchronization source, then according to the pre-settings, no synchronization message is sent or synchronization messages are only sent through PSBCH based on the local device's internal clock.

[0232] Devices with synchronization levels of the second, third, and fourth levels randomly enter the synchronization signal receiving state. If a synchronization message is received and its priority is higher than the local synchronization source, the local device updates the synchronization source; otherwise, the local device maintains the original synchronization state.

[0233] First application scenario of the embodiment of the present invention

[0234] The system parameter configuration of Internet of Vehicles equipment such as RSU and OBU is as follows: system bandwidth is 20MHz, half-duplex mode is supported, subcarrier spacing is 15kHz, cyclic prefix (CP) length is 4.687μs (5.208μs (symbol 0)), modulation mode is quadrature phase shift keying (QPSK), and the maximum transmission power is 23dBm.

[0235] like Figure 6As shown in the figure, the application scenario of the Internet of Vehicles includes 4 RSUs and 1 OBU, among which only RSU1 can receive GNSS signals. The initial state of the 4 RSUs and 1 OBU is out of sync. After startup, they first receive GNSS signals without sending synchronization messages. RSU1 receives GNSS signals and enters the synchronization state, setting the inCoverage flag to 1, the SLSS ID to 0, and the synchronization level to the first synchronization level. RSU1 sends synchronization messages through PSCCH&PSSCH and PSBCH respectively, and PSSCH can be sent in TDM or FDM mode, and PSBCH is sent in even reserved subframes.

[0236] RSU2 receives the synchronization message sent by RSU1, enters the synchronization state, sets the inCoverage flag to 0, SLSSID to 0, and the synchronization level to the second synchronization level; RSU2 sends synchronization messages through PSCCH&PSSCH and PSBCH respectively, and PSSCH can be sent in TDM or FDM mode, and PSBCH is sent in odd reserved subframes.

[0237] RSU3 receives the synchronization message sent by RSU2, enters the synchronization state, sets the inCoverage flag to 0, the SLSSID to 168, and the synchronization level to the third synchronization level; RSU3 sends synchronization messages through PSCCH&PSSCH and PSBCH respectively, and PSSCH can be sent in TDM or FDM mode, and PSBCH is sent in even reserved subframes.

[0238] RSU4 and OBU1 receive the synchronization message sent by RSU3 and enter the synchronization state, and the synchronization level is the third synchronization level; the inCoverage flag of RSU4 and OBU1 is 0, and the SLSS ID is 168. RSU4 and OBU1 send synchronization messages through PSCCH&PSSCH and PSBCH respectively, and PSSCH can be sent in TDM or FDM mode, and PSBCH is sent in odd reserved subframes.

[0239] Second application scenario of the embodiment of the present invention

[0240] When the local device receives multiple synchronous messages at the same time, Figure 7Take this as an example to illustrate. RSU2 receives two synchronization messages from RSU1 and RSU3 respectively, where the synchronization signal power of RSU1 is P1, the inCoverage flag is 0, the SLSSID is 0, the synchronization level is the second synchronization level, RSU1 selects TDM to send PSSCH, and RSU1 sends synchronization messages through PSBCH in odd reserved subframes; the synchronization signal power of RSU3 is P3, the inCoverage flag is 0, the SLSS ID is 168, the synchronization level is the third synchronization level, RSU3 selects TDM to send PSSCH, and RSU3 sends synchronization messages through PSBCH in even reserved subframes; and P1 and P3 are both greater than the power threshold, then RSU2 is synchronized with RSU1, the inCoverage flag is 0, the SLSS ID is 168, the synchronization level is the third synchronization level, RSU2 sends synchronization messages through PSCCH&PSSCH and PSBCH respectively, and RSU2 selects TDM to send PSSCH; if P1>P3, RSU1 sends synchronization messages through PSBCH in even reserved subframes.

[0241] It should be noted that the implementation method of the embodiment of the present invention is applicable to the distributed architecture of the Internet of Vehicles, complies with industry standards, has wide applicability, can accurately realize synchronous coordination between a large number of terminals, and improves the efficiency of synchronization.

[0242] like Figure 8 As shown, the embodiment of the present invention further provides a synchronization device 80, which is applied to a first terminal device, including:

[0243] A first sending module 81, configured to send a pilot signal and a first synchronization control signaling to a second terminal device;

[0244] The first synchronization control signaling is used to indicate:

[0245] a synchronization level of the first terminal device;

[0246] The frame number and subframe number for synchronization.

[0247] Optionally, the first sending module 81 is used to:

[0248] Sending the first synchronization control signaling to the second terminal device via a direct link control channel PSCCH; or

[0249] Sending the first synchronization control signaling to the second terminal device via the PSCCH and the direct link shared channel PSSCH;

[0250] The pilot signal is a demodulation reference signal DMRS.

[0251] Optionally, the first sending module 81 is used to:

[0252] Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and

[0253] Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH;

[0254] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0255] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0256] Wherein, N is less than or equal to 7.

[0257] Alternatively, according to the formula:

[0258] Indicating whether the PSCCH carries the first synchronization control signaling;

[0259] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0260] Optionally, if the synchronization levels indicated by the first synchronization control signaling sent by the first terminal device at different times are different, the first terminal device sends the second part of the first synchronization control signaling indicating different synchronization levels on the PSSCH using frequency division multiplexing FDM or time division multiplexing TDM.

[0261] Optionally, the synchronization device of the embodiment of the present invention further includes:

[0262] A second sending module, used for sending a second synchronization control signaling to a second terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe;

[0263] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0264] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0265] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0266] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0267] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0268] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0269] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the reserved subframe occupancy mode for the first terminal device to send the second synchronization control signaling of different synchronization levels includes:

[0270] When the first terminal device is at a first synchronization level, the first terminal device sends a second synchronization control signaling on a second reserved subframe;

[0271] When the first terminal device is at a second synchronization level, the first terminal device sends a second synchronization control signaling on a first reserved subframe;

[0272] When the first terminal device is at the third synchronization level, the first terminal device sends a second synchronization control signaling on a first target reserved subframe, where the first target reserved subframe is the one with lower receiving power between the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0273] When the first terminal device is at the fourth synchronization level, the first terminal device randomly selects a subframe based on an internal clock to send a second synchronization control signaling.

[0274] Optionally, the synchronization level of the first terminal device includes one of the following:

[0275] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0276] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0277] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0278] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0279] The priority of the synchronization levels is in the order from high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0280] It should be noted that the synchronization device embodiment is a device that corresponds one-to-one to the above-mentioned method embodiment. All implementation methods in the above-mentioned method embodiment are applicable to the embodiment of the device and can achieve the same technical effect.

[0281] like Fig. 9 As shown, an embodiment of the present invention further provides a terminal device 90, which is a first terminal device, including a processor 91, a transceiver 92, a memory 93, and a program stored in the memory 93 and executable on the processor 91; wherein the transceiver 92 is connected to the processor 91 and the memory 93 through a bus interface, wherein the processor 91 is used to read the program in the memory and execute the following process:

[0282] Sending the pilot signal and the first synchronization control signaling to the second terminal device through the transceiver 92;

[0283] The first synchronization control signaling is used to indicate:

[0284] a synchronization level of the first terminal device;

[0285] The frame number and subframe number for synchronization.

[0286] It should be noted that in Fig. 9 In the embodiment, the bus architecture may include any number of interconnected buses and bridges, specifically one or more processors represented by processor 91 and various circuits of memory represented by memory 93 are linked together. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface. The transceiver 92 may be a plurality of components, namely, a transmitter and a transceiver, providing a unit for communicating with various other devices on a transmission medium. For different terminals, the user interface 94 may also be an interface capable of externally connecting or internally connecting required devices, and the connected devices include but are not limited to a keypad, a display, a speaker, a microphone, a joystick, and the like. The processor 91 is responsible for managing the bus architecture and general processing, and the memory 93 may store data used by the processor 91 when performing operations.

[0287] Optionally, the processor implements the following steps when executing a program for sending a pilot signal and a first synchronization control signaling to a second terminal device:

[0288] Sending the first synchronization control signaling to the second terminal device via a direct link control channel PSCCH; or

[0289] Sending the first synchronization control signaling to the second terminal device via the PSCCH and the direct link shared channel PSSCH;

[0290] The pilot signal is a demodulation reference signal DMRS.

[0291] Optionally, when the processor executes the program of sending the first synchronization control signaling to the second terminal device through the PSCCH and the direct link shared channel PSSCH, the following steps are implemented:

[0292] Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and

[0293] Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH;

[0294] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0295] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0296] Wherein, N is less than or equal to 7.

[0297] Alternatively, according to the formula:

[0298] Indicating whether the PSCCH carries the first synchronization control signaling;

[0299] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0300] Optionally, if the synchronization levels indicated by the first synchronization control signaling sent by the first terminal device at different times are different, the first terminal device sends the second part of the first synchronization control signaling indicating different synchronization levels on the PSSCH using frequency division multiplexing FDM or time division multiplexing TDM.

[0301] Optionally, the processor is used to read a program in the memory and is further used to execute:

[0302] Sending a second synchronization control signaling to the second terminal device through the transceiver 92 on the direct link broadcast channel PSBCH sent through the reserved subframe;

[0303] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0304] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0305] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0306] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0307] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0308] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0309] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the reserved subframe occupancy mode for the first terminal device to send the second synchronization control signaling of different synchronization levels includes:

[0310] When the first terminal device is at a first synchronization level, the first terminal device sends a second synchronization control signaling on a second reserved subframe;

[0311] When the first terminal device is at a second synchronization level, the first terminal device sends a second synchronization control signaling on a first reserved subframe;

[0312] When the first terminal device is at the third synchronization level, the first terminal device sends a second synchronization control signaling on a first target reserved subframe, where the first target reserved subframe is the one with lower receiving power between the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0313] When the first terminal device is at the fourth synchronization level, the first terminal device randomly selects a subframe based on an internal clock to send a second synchronization control signaling.

[0314] Optionally, the synchronization level of the first terminal device includes one of the following:

[0315] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0316] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0317] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0318] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0319] The priority of the synchronization levels is in the order of high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0320] An embodiment of the present invention further provides a readable storage medium, on which a computer program is stored, wherein when the program is executed by a processor, the steps of the synchronization method applied to the first terminal device are implemented.

[0321] An embodiment of the present invention further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement each process of an embodiment of a synchronization method applied to a first terminal device, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0322] like Fig.10 As shown, the embodiment of the present invention further provides a synchronization device 100, which is applied to a second terminal device, including:

[0323] The judging module 101 is configured to judge whether a first signal is received, wherein the first signal includes: a pilot signal and a first synchronization control signaling sent by at least one first terminal device;

[0324] A first determination module 102, configured to determine a synchronization source of the second terminal device if the first signal is received;

[0325] A second determining module 103, configured to determine a synchronization level of the second terminal device according to a synchronization source of the second terminal device;

[0326] The first synchronization control signaling is used to indicate:

[0327] a synchronization level of the first terminal device;

[0328] The frame number and subframe number for synchronization.

[0329] Optionally, the pilot signal and the first synchronization control signaling sent by the at least one first terminal device include:

[0330] A first synchronization control signaling sent by at least one first terminal device via a direct link control channel PSCCH; or

[0331] A first synchronization control signaling sent by at least one first terminal device via the PSCCH and the direct link shared channel PSSCH;

[0332] The pilot signal is a demodulation reference signal DMRS.

[0333] Optionally, in the case where the at least one first terminal device sends the first synchronization control signaling through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries the first part of the first synchronization control signaling, and the PSSCH carries the second part of the first synchronization control signaling;

[0334] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0335] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0336] Wherein, N is less than or equal to 7.

[0337] Alternatively, according to the formula:

[0338] Indicating whether the PSCCH carries the first synchronization control signaling;

[0339] Among them, a jis the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0340] Optionally, the second part of the first synchronization control signaling of the first terminal devices of different synchronization levels is sent on the PSSCH in a frequency division multiplexing FDM or time division multiplexing TDM manner.

[0341] Optionally, the first determining module 102 is configured to:

[0342] The first terminal device corresponding to a first synchronization control signaling with the highest synchronization level in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

[0343] Optionally, the first signal further includes: a second synchronization control signaling and / or a global navigation satellite system GNSS signal sent by at least one first terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe;

[0344] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0345] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0346] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0347] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0348] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0349] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0350] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the manner in which the second terminal device receives the second synchronization control signaling of different synchronization levels includes:

[0351] When the first terminal device is at a first synchronization level, the second terminal device receives a second synchronization control signaling on a second reserved subframe;

[0352] When the first terminal device is at a second synchronization level, the second terminal device receives a second synchronization control signaling on a first reserved subframe;

[0353] When the first terminal device is at the third synchronization level, the second terminal device receives the second synchronization control signaling on the first target reserved subframe, where the first target reserved subframe is a reserved subframe with low receiving power among the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0354] When the first terminal device is at the fourth synchronization level, the second terminal device receives a second synchronization control signaling on a second target reserved subframe, where the second target reserved subframe is a subframe randomly selected by the first terminal device based on an internal clock.

[0355] Optionally, the first determining module 102 is configured to:

[0356] In the case where the first signal includes a GNSS signal, using the GNSS signal as a synchronization source for the second terminal device;

[0357] When the first signal does not include a GNSS signal, the first terminal device corresponding to the highest synchronization level in the first signaling is determined as the synchronization source of the second terminal device, and the first signaling is the first synchronization control signaling, or the first signaling is the first synchronization control signaling and the second synchronization control signaling.

[0358] Optionally, the synchronization level of the first terminal device includes one of the following:

[0359] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0360] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0361] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0362] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0363] The priority of the synchronization levels is in the order from high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0364] It should be noted that the synchronization device embodiment is a device that corresponds one-to-one to the above-mentioned method embodiment. All implementation methods in the above-mentioned method embodiment are applicable to the embodiment of the device and can achieve the same technical effect.

[0365] An embodiment of the present invention further provides a terminal device, which is a second terminal device, comprising a processor, a transceiver, a memory, and a program stored in the memory and executable on the processor; wherein the transceiver is connected to the processor and the memory via a bus interface, wherein the processor is used to read the program in the memory and execute the following process:

[0366] Determining whether a first signal is received, the first signal comprising: a pilot signal and a first synchronization control signaling sent by at least one first terminal device;

[0367] If the first signal is received, determining a synchronization source of the second terminal device;

[0368] determining a synchronization level of the second terminal device according to a synchronization source of the second terminal device;

[0369] The first synchronization control signaling is used to indicate:

[0370] a synchronization level of the first terminal device;

[0371] The frame number and subframe number for synchronization.

[0372] It should be noted that the terminal device in this embodiment is Fig. 9 The structure of the terminal device is the same as that of the terminal device in the embodiment, and the specific structure will not be repeated here.

[0373] Optionally, the pilot signal and the first synchronization control signaling sent by the at least one first terminal device include:

[0374] A first synchronization control signaling sent by at least one first terminal device via a direct link control channel PSCCH; or

[0375] A first synchronization control signaling sent by at least one first terminal device via the PSCCH and the direct link shared channel PSSCH;

[0376] The pilot signal is a demodulation reference signal DMRS.

[0377] Optionally, in the case where the at least one first terminal device sends the first synchronization control signaling through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries the first part of the first synchronization control signaling, and the PSSCH carries the second part of the first synchronization control signaling;

[0378] Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization.

[0379] Optionally, the first part is carried by N bits in reserved bits of direct link control information SCI in the PSCCH;

[0380] Wherein, N is less than or equal to 7.

[0381] Alternatively, according to the formula:

[0382] Indicating whether the PSCCH carries the first synchronization control signaling;

[0383] Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

[0384] Optionally, the second part of the first synchronization control signaling of the first terminal devices of different synchronization levels is sent on the PSSCH in a frequency division multiplexing FDM or time division multiplexing TDM manner.

[0385] Optionally, when the processor executes the program for determining the synchronization source of the second terminal device if the first signal is received, the following steps are implemented:

[0386] The first terminal device corresponding to a first synchronization control signaling with the highest synchronization level in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

[0387] Optionally, the first signal further includes: a second synchronization control signaling and / or a global navigation satellite system GNSS signal sent by at least one first terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe;

[0388] Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

[0389] Optionally, the correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following:

[0390] When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level;

[0391] When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level;

[0392] When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level;

[0393] When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

[0394] Optionally, the through link synchronization signal transmission period in the PSBCH includes a first reserved subframe and a second reserved subframe, and the manner in which the second terminal device receives the second synchronization control signaling of different synchronization levels includes:

[0395] When the first terminal device is at a first synchronization level, the second terminal device receives a second synchronization control signaling on a second reserved subframe;

[0396] When the first terminal device is at a second synchronization level, the second terminal device receives a second synchronization control signaling on a first reserved subframe;

[0397] When the first terminal device is at the third synchronization level, the second terminal device receives the second synchronization control signaling on the first target reserved subframe, where the first target reserved subframe is a reserved subframe with low receiving power among the first reserved subframe and the second reserved subframe detected by the first terminal device;

[0398] When the first terminal device is at the fourth synchronization level, the second terminal device receives a second synchronization control signaling on a second target reserved subframe, where the second target reserved subframe is a subframe randomly selected by the first terminal device based on an internal clock.

[0399] Optionally, when the processor executes the program for determining the synchronization source of the second terminal device if the first signal is received, the following steps are implemented:

[0400] In the case where the first signal includes a GNSS signal, using the GNSS signal as a synchronization source for the second terminal device;

[0401] When the first signal does not include a GNSS signal, the first terminal device corresponding to the highest synchronization level in the first signaling is determined as the synchronization source of the second terminal device, and the first signaling is the first synchronization control signaling, or the first signaling is the first synchronization control signaling and the second synchronization control signaling.

[0402] Optionally, the synchronization level of the first terminal device includes one of the following:

[0403] A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal;

[0404] A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level;

[0405] A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level;

[0406] A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal;

[0407] The priority of the synchronization levels is in the order from high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

[0408] An embodiment of the present invention further provides a readable storage medium, on which a computer program is stored, wherein when the program is executed by a processor, the steps of the synchronization method applied to a second terminal device are implemented.

[0409] An embodiment of the present invention further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement each process of an embodiment of a synchronization method applied to a second terminal device, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0410] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0411] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0412] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0413] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary personnel in this technical field, several improvements and modifications can be made without departing from the principles described in the present invention. These improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A synchronization method, characterized in that: The method is executed by the first terminal device and includes: Sending a pilot signal and a first synchronization control signaling to a second terminal device; The first synchronization control signaling is used to indicate: a synchronization level of the first terminal device; The frame number and subframe number for synchronization; The sending of the pilot signal and the first synchronization control signaling to the second terminal device includes: Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH; Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization; the pilot signal is the demodulation reference signal DMRS.

2. The synchronization method according to claim 1, characterized in that: The first part is carried by N bits in the reserved bits of the direct link control information SCI in the PSCCH; Wherein, N is less than or equal to 7.

3. The synchronization method according to claim 2, characterized in that: According to the formula: Indicating whether the PSCCH carries the first synchronization control signaling; Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

4. The synchronization method according to claim 1, characterized in that: If the synchronization levels indicated by the first synchronization control signaling sent by the first terminal device at different times are different, the first terminal device sends the second part of the first synchronization control signaling indicating different synchronization levels on the PSSCH using frequency division multiplexing FDM or time division multiplexing TDM.

5. The synchronization method according to claim 1, characterized in that: Also includes: Sending a second synchronization control signaling to the second terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe; Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

6. The synchronization method according to claim 5, characterized in that: The correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following: When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level; When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level; When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level; When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

7. The synchronization method according to claim 5, characterized in that: The transmission period of the direct link synchronization signal in the PSBCH includes a first reserved subframe and a second reserved subframe, and the reserved subframe occupancy mode for the first terminal device to send the second synchronization control signaling of different synchronization levels includes: When the first terminal device is at a first synchronization level, the first terminal device sends a second synchronization control signaling on a second reserved subframe; When the first terminal device is at a second synchronization level, the first terminal device sends a second synchronization control signaling on a first reserved subframe; When the first terminal device is at the third synchronization level, the first terminal device sends a second synchronization control signaling on a first target reserved subframe, where the first target reserved subframe is the one with lower receiving power between the first reserved subframe and the second reserved subframe detected by the first terminal device; When the first terminal device is at the fourth synchronization level, the first terminal device randomly selects a subframe based on an internal clock to send a second synchronization control signaling.

8. The synchronization method according to claim 1 or 5, characterized in that: The synchronization level of the first terminal device includes one of the following: A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal; A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level; A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level; A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal; The priority of the synchronization levels is in the order of high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

9. A synchronization method, characterized in that: The method is executed by the second terminal device and includes: Determining whether a first signal is received, the first signal comprising: a pilot signal and a first synchronization control signaling sent by at least one first terminal device; If the first signal is received, determining a synchronization source of the second terminal device; determining a synchronization level of the second terminal device according to a synchronization source of the second terminal device; The first synchronization control signaling is used to indicate: a synchronization level of the first terminal device; The frame number and subframe number for synchronization; The pilot signal and the first synchronization control signaling sent by the at least one first terminal device include: In the case of a first synchronization control signaling sent by the at least one first terminal device through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries a first part of the first synchronization control signaling, and the PSSCH carries a second part of the first synchronization control signaling; The first part is used to indicate whether the PSCCH carries the first synchronization control signaling. In the case where the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and the subframe number for synchronization; The pilot signal is a demodulation reference signal DMRS.

10. The synchronization method according to claim 9, characterized in that: The first part is carried by N bits in the reserved bits of the direct link control information SCI in the PSCCH; Wherein, N is less than or equal to 7.

11. The synchronization method according to claim 10, characterized in that: According to the formula: Indicating whether the PSCCH carries the first synchronization control signaling; Among them, a j is the value of the jth bit; i=31-N+1; the value of a is used to indicate whether the PSCCH carries the first synchronization control signaling. If a>0, it means that the PSCCH carries the first synchronization control signaling. If a=0, it means that the PSCCH does not carry the first synchronization control signaling.

12. The synchronization method according to claim 9, characterized in that: The second part of the first synchronization control signaling of the first terminal devices of different synchronization levels is sent on the PSSCH in a frequency division multiplexing FDM or time division multiplexing TDM manner.

13. The synchronization method according to claim 9, characterized in that: If the first signal is received, determining the synchronization source of the second terminal device includes: The first terminal device corresponding to a first synchronization control signaling with the highest synchronization level in the first synchronization control signaling is determined as the synchronization source of the second terminal device.

14. The synchronization method according to claim 9, characterized in that: The first signal further includes: a second synchronization control signaling and / or a global navigation satellite system GNSS signal sent by at least one first terminal device on a direct link broadcast channel PSBCH sent through a reserved subframe; Among them, the second synchronization control signaling is used to indicate the synchronization level of the first terminal device; the second synchronization control signaling includes: indication information of whether the first terminal device is within the coverage of the GNSS and the direct link synchronization signal index.

15. The synchronization method according to claim 14, characterized in that: The correspondence between the synchronization level, the indication information, and the through link synchronization signal index includes at least one of the following: When the indication information is 1 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the first synchronization level; When the indication information is 0 and the through link synchronization signal index is 0, it indicates that the synchronization level of the first terminal device is the second synchronization level; When the indication information is 0 and the through link synchronization signal index is a preset value, it indicates that the synchronization level of the first terminal device is the third synchronization level; When the indication information is 0 and the direct link synchronization signal index is a value greater than a preset value, it indicates that the synchronization level of the first terminal device is the fourth synchronization level.

16. The synchronization method according to claim 14, characterized in that: The transmission period of the direct link synchronization signal in the PSBCH includes a first reserved subframe and a second reserved subframe, and the manner in which the second terminal device receives the second synchronization control signaling of different synchronization levels includes: When the first terminal device is at a first synchronization level, the second terminal device receives a second synchronization control signaling on a second reserved subframe; When the first terminal device is at a second synchronization level, the second terminal device receives a second synchronization control signaling on a first reserved subframe; When the first terminal device is at the third synchronization level, the second terminal device receives the second synchronization control signaling on the first target reserved subframe, where the first target reserved subframe is a reserved subframe with low receiving power among the first reserved subframe and the second reserved subframe detected by the first terminal device; When the first terminal device is at the fourth synchronization level, the second terminal device receives a second synchronization control signaling on a second target reserved subframe, where the second target reserved subframe is a subframe randomly selected by the first terminal device based on an internal clock.

17. The synchronization method according to claim 14, characterized in that: If the first signal is received, determining the synchronization source of the second terminal device includes: In the case where the first signal includes a GNSS signal, using the GNSS signal as a synchronization source for the second terminal device; When the first signal does not include a GNSS signal, the first terminal device corresponding to the highest synchronization level in the first signaling is determined as the synchronization source of the second terminal device, and the first signaling is the first synchronization control signaling, or the first signaling is the first synchronization control signaling and the second synchronization control signaling.

18. The synchronization method according to claim 9 or 14, characterized in that: The synchronization level of the first terminal device includes one of the following: A first synchronization level, indicating that the synchronization source of the first terminal device is a Global Navigation Satellite System GNSS signal; A second synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the first synchronization level; A third synchronization level, indicating that the synchronization source of the first terminal device is a terminal device of the second synchronization level or the third synchronization level; A fourth synchronization level indicates that the first terminal device cannot receive a synchronization signal; The priority of the synchronization levels is in the order of high to low: first synchronization level, second synchronization level, third synchronization level, fourth synchronization level.

19. A terminal device, characterized in that: include: A processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the steps of the synchronization method according to any one of claims 1 to 18 are implemented.

20. A synchronization device, applied to a first terminal device, characterized in that: include: A sending module, used for sending a pilot signal and a first synchronization control signaling to a second terminal device; The first synchronization control signaling is used to indicate: a synchronization level of the first terminal device; The frame number and subframe number for synchronization; Wherein, the sending module is specifically used for: Sending a first part of the first synchronization control signaling to the second terminal device on the PSCCH; and Sending a second part of the first synchronization control signaling to the second terminal device on the PSSCH; Among them, the first part is used to indicate whether the PSCCH carries the first synchronization control signaling. When the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and subframe number for synchronization; the pilot signal is the demodulation reference signal DMRS.

21. A synchronization device, applied to a second terminal device, characterized in that: include: A determination module, configured to determine whether a first signal is received, wherein the first signal includes: a pilot signal and a first synchronization control signaling sent by at least one first terminal device; A first determination module, configured to determine a synchronization source of the second terminal device if the first signal is received; A second determining module, configured to determine a synchronization level of the second terminal device according to a synchronization source of the second terminal device; The first synchronization control signaling is used to indicate: a synchronization level of the first terminal device; The frame number and subframe number for synchronization; The pilot signal and the first synchronization control signaling sent by the at least one first terminal device include: In the case of a first synchronization control signaling sent by the at least one first terminal device through the PSCCH and the direct link shared channel PSSCH, the PSCCH carries a first part of the first synchronization control signaling, and the PSSCH carries a second part of the first synchronization control signaling; The first part is used to indicate whether the PSCCH carries the first synchronization control signaling. In the case where the PSCCH carries the first synchronization control signaling, the PSSCH indicated by the PSCCH carries the second part of the first synchronization control signaling; the second part is used to indicate the synchronization level of the first terminal device, the frame number and the subframe number for synchronization; The pilot signal is a demodulation reference signal DMRS.

22. A readable storage medium, characterized in that: The readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the synchronization method according to any one of claims 1 to 18.

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