WO2022088394A1 - 同步方法、车联网终端及存储介质 - Google Patents

同步方法、车联网终端及存储介质 Download PDF

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Publication number
WO2022088394A1
WO2022088394A1 PCT/CN2020/134361 CN2020134361W WO2022088394A1 WO 2022088394 A1 WO2022088394 A1 WO 2022088394A1 CN 2020134361 W CN2020134361 W CN 2020134361W WO 2022088394 A1 WO2022088394 A1 WO 2022088394A1
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WIPO (PCT)
Prior art keywords
synchronization signal
synchronization
optimal
slss
signal
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PCT/CN2020/134361
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English (en)
French (fr)
Inventor
李志远
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Tcl通讯（宁波）有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
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Priority to US18/250,547 priority Critical patent/US20240121735A1/en
Publication of WO2022088394A1 publication Critical patent/WO2022088394A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/0035—Synchronisation arrangements detecting errors in frequency or phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/0015—Synchronization between nodes one node acting as a reference for the others
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/002—Mutual synchronization

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a synchronization method, an Internet of Vehicles terminal, and a storage medium.
  • V2X Vehicle to X
  • 5G Vehicle to X
  • V2X adopts SideLink (edge connection) technology in ProSe (close-range communication) technology to realize direct communication between vehicle network terminals.
  • SideLink is based on the 5G air interface NR technology (NR V2X), which meets the low latency, high reliability, and high speed standards required by V2X.
  • NR has high requirements for time-frequency offset synchronization, that is, synchronization of frequency, phase, and time domain, and all three kinds of synchronization must depend on time domain synchronization.
  • SideLink synchronization scenario the IoV terminal directly connected to the base station receives the synchronization signal sent by the base station for synchronization; the IoV terminal not directly connected to the base station is synchronized according to the SLSS signal sent by other IoV terminals. If the networked terminals continue to synchronize according to this chain, the accumulated error of the chain will be enlarged, thereby reducing the synchronization accuracy of the Internet of Vehicles terminals.
  • Embodiments of the present application provide a synchronization method, a car networking terminal and a storage medium, which can reduce the synchronization error of the car networking terminal and improve the synchronization accuracy.
  • an embodiment of the present application provides a synchronization method, which is applied to an Internet of Vehicles terminal, and the method includes:
  • Synchronization is performed according to the optimal synchronization signal.
  • performing synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal to determine an optimal synchronization signal specifically includes:
  • the selecting an optimal SLSS synchronization signal from the at least one SLSS synchronization signal specifically includes:
  • the SLSS synchronization signal with the highest signal strength is selected from the SLSS synchronization signals with the highest priority as the optimal SLSS synchronization signal.
  • performing synchronization error detection on the optimal SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal specifically includes:
  • the time domain positions of the two synchronization errors are detected to determine the optimal synchronization signal according to the detection results.
  • the detection of the time domain positions of the two synchronization errors to determine the optimal synchronization signal according to the detection result specifically includes:
  • the method further includes:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the method further includes:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the method further includes:
  • the crystal oscillator of the car networking terminal is used as a synchronization source for synchronization.
  • an embodiment of the present application further provides a synchronization device, which is applied to a terminal of the Internet of Vehicles, and the device includes:
  • Detection module used to detect synchronization signal
  • an acquisition module configured to acquire a GNSS synchronization signal when at least one SLSS synchronization signal is detected
  • a determining module configured to perform synchronization error detection on the optimal SLSS synchronization signal and the GNSS synchronization signal, respectively, to determine an optimal synchronization signal
  • a synchronization module configured to perform synchronization according to the optimal synchronization signal.
  • embodiments of the present application further provide a computer-readable storage medium, where a plurality of instructions are stored in the storage medium, and the instructions are adapted to be loaded by a processor to perform the following steps:
  • Synchronization is performed according to the optimal synchronization signal.
  • the processor when the processor performs the synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal, the processor specifically performs the following steps:
  • the processor when the processor executes the selecting an optimal SLSS synchronization signal from the at least one SLSS synchronization signal, the processor specifically performs the following steps:
  • the SLSS synchronization signal with the highest signal strength is selected from the SLSS synchronization signals with the highest priority as the optimal SLSS synchronization signal.
  • the processor when the processor performs the synchronization error detection on the optimal SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal, the processor specifically performs the following steps:
  • the time domain positions of the two synchronization errors are detected to determine the optimal synchronization signal according to the detection results.
  • the processor when the processor performs the detection of the time domain positions of the two synchronization errors to determine the optimal synchronization signal according to the detection result, the processor specifically performs the following steps:
  • the processor further performs the following steps:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the processor further performs the following steps:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the processor further performs the following steps:
  • the crystal oscillator of the car networking terminal is used as a synchronization source for synchronization.
  • the present application further provides an Internet of Vehicles terminal, including a processor and a memory, the processor is electrically connected to the memory, the memory is used to store instructions and data, and the processor is used to perform the following steps :
  • Synchronization is performed according to the optimal synchronization signal.
  • the processor when the processor performs the synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal, the processor specifically performs the following steps:
  • the processor when the processor performs the synchronization error detection on the optimal SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal, the processor specifically performs the following steps:
  • the time domain positions of the two synchronization errors are detected to determine the optimal synchronization signal according to the detection results.
  • the processor when the processor performs the detection of the time domain positions of the two synchronization errors to determine the optimal synchronization signal according to the detection result, the processor specifically performs the following steps:
  • the synchronization method, the Internet of Vehicles terminal and the storage medium provided by the present application can obtain the GNSS synchronization signal when the Internet of Vehicles terminal detects at least one SLSS synchronization signal, and perform the optimal SLSS synchronization signal and the GNSS synchronization signal respectively.
  • Synchronization error detection is used to determine the optimal synchronization signal, and perform synchronization according to the optimal synchronization signal to avoid accumulating synchronization errors, thereby reducing synchronization errors and improving synchronization accuracy.
  • FIG. 1 is a schematic structural diagram of an Internet of Vehicles system provided by an embodiment of the present application.
  • FIG. 2 is another schematic structural diagram of the Internet of Vehicles system provided by an embodiment of the present application.
  • FIG. 3 is a schematic flowchart of a synchronization method provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a cyclic prefix of a signal sent by an Internet of Vehicles terminal in a synchronization method provided by an embodiment of the present application;
  • FIG. 5 is another schematic flowchart of a synchronization method provided by an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a synchronization apparatus provided by an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of an Internet of Vehicles terminal provided by an embodiment of the present application.
  • FIG. 8 is another schematic structural diagram of the Internet of Vehicles terminal provided by an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a car networking system.
  • the IoV environment is divided into three situations due to different network coverage, namely network coverage area, no network coverage area and partial network coverage area.
  • SideLink's PC5 interface can be used in these three situations, but the NR UU interface is in the There is no connection in areas with no network coverage, and may not exist in some areas of network coverage. Therefore, as shown in FIG.
  • the IoV terminal 12 is located in the network coverage area, the base station (qNodeB) 11 is connected to the IoV terminal 12 through the NR UU, the vehicle network terminal 13 is located in the non-network coverage area, and the base station 11 and IoV terminal 13 cannot be connected
  • the vehicle network terminal 12 can be connected to the vehicle network terminal 13 via SideLink.
  • the direct communication between two IoV terminals makes these two IoV terminals form a group of D2D (device to device) terminal.
  • D2D terminal 23 two IoV terminals are located within the coverage of the base station 21 ; in the D2D terminal 24 , one IoV terminal is located within the coverage area of the base station 21 , and the other IoV terminal is located in the coverage area of the base station 21 . Outside the coverage area of the base station; in the D2D terminal 25, one IoV terminal is located within the coverage area of the base station 21, and the other IoV terminal is located within the coverage area of the base station 22; in the D2D terminal 26, another IoV terminal is located in the base station out of coverage.
  • FIG. 3 is a schematic flowchart of a synchronization method provided by an embodiment of the present application.
  • the synchronization method is applied to a terminal of the Internet of Vehicles.
  • the specific process of the synchronization method may be as follows:
  • the IoV terminal detects the synchronization signal around it. If the IoV terminal is within the coverage of the base station, the IoV terminal can detect the synchronization signal sent by the base station, and the synchronization signal sent by the base station is PSS (Primary Synchronization Signal, main synchronization signal) or SSS (Secondary Synchronization Signal, secondary synchronization signal).
  • PSS Primary Synchronization Signal, main synchronization signal
  • SSS Secondary Synchronization Signal, secondary synchronization signal
  • both the two vehicle network terminals constituting the D2D terminal 23 can detect the PSS/SSS synchronization signal sent by the base station 21
  • the vehicle network terminal in the D2D terminal 25 located within the coverage of the base station 21 can detect the signal sent by the base station 21 .
  • the PSS/SSS synchronization signal, and the IoV terminal located within the coverage of the base station 22 can detect the PSS/SSS synchronization signal sent by the base station 22 .
  • the synchronization signal detected by the IoV terminal is the SLSS (SideLink Synchronization Signal) sent by other IoV terminals. Signal, SideLink sync signal).
  • the IoV terminal located outside the coverage area of the base station can detect the SLSS synchronization signal sent by another IoV terminal.
  • the IoV terminals located outside the coverage area of the base station may not detect any synchronization signal, for example, the two IoV terminals constituting the D2D terminal 26 in FIG. 2 .
  • the PSS/SSS synchronization signal sent by the base station has the highest priority and can be set to 0.
  • the method further includes: when the PSS/SSS synchronization signal is detected, performing synchronization according to the PSS/SSS synchronization signal; and calibrating the crystal oscillator of the vehicle networking terminal according to the PSS/SSS synchronization signal.
  • the IoV terminal detects the PSS/SSS synchronization signal sent by the base station, it will directly synchronize the clock according to the PSS/SSS synchronization signal, that is, the base station is used as the synchronization source.
  • the IoV terminal calibrates its own crystal oscillator according to the PSS/SSS synchronization signal, so as to avoid the subsequent failure to detect any synchronization signal, the crystal oscillator can be used as a synchronization source to reduce synchronization errors.
  • the IoV terminal sends an SLSS synchronization signal to the outside, and sets the priority of the SLSS synchronization signal to 1.
  • the higher the priority value, the lower the priority, that is, the priority of the SLSS synchronization signal The priority of the SSS sync signal. If the highest priority of the synchronization signals that can be detected by other IoV terminals is 1, the priority of the SLSS synchronization signals sent by other IoV terminals is set to 2, and so on, if one IoV terminal A can detect The highest priority in the synchronization signal is n, then the priority of the SLSS synchronization signal sent by the IoV terminal A to the outside is set to n+1, n ⁇ 0.
  • the GNSS synchronization signal is acquired when at least one SLSS synchronization signal is detected.
  • the IoV terminal does not detect the PSS/SSS synchronization signal sent by the base station, but only detects the SLSS synchronization signal sent by other IoV terminals.
  • the priority If it is too low, the accumulated synchronization error is too large, so GNSS (Global Navigation Satellite System, global satellite navigation system) synchronization signal.
  • the GNSS module of the IoV terminal can receive the synchronization signal sent by the GNSS, that is, the GNSS synchronization signal. That is to say, when the IoV terminal cannot be directly synchronized with the base station, the GNSS synchronization signal is used to select the optimal synchronization signal of the IoV terminal to reduce the synchronization error of the IoV terminal.
  • Synchronization error detection is performed on the at least one SLSS synchronization signal and the GNSS synchronization signal, respectively, to determine an optimal synchronization signal.
  • the IoV terminal compares and detects the SLSS synchronization signal received from other IoV terminals and the GNSS synchronization signal obtained from the GNSS. Select an optimal SLSS synchronization signal from the SLSS synchronization signal, and then compare and detect with the GNSS synchronization signal.
  • performing synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal respectively in step 103 to determine the optimal synchronization signal includes:
  • the optimal SLSS synchronization signal can be considered from two aspects of priority and signal strength.
  • the selecting the optimal SLSS synchronization signal from the at least one SLSS synchronization signal includes:
  • the SLSS synchronization signal with the highest signal strength is selected from the SLSS synchronization signals with the highest priority as the optimal SLSS synchronization signal.
  • the IoV terminal can identify the priority value corresponding to the SLSS synchronization signal, and select the lowest priority value from all the received SLSS synchronization signals (that is, the priority value). the highest level) SLSS synchronization signal. If there is only one SLSS synchronization signal with the smallest priority value selected, the SLSS synchronization signal will be regarded as the optimal SLSS synchronization signal; if there are still multiple SLSS synchronization signals with the smallest priority value selected, continue to compare the selected multiple SLSS synchronization signals. The signal strength of the SLSS synchronization signal, from which the SLSS signal with the highest signal strength is selected as the optimal SLSS synchronization signal.
  • the optimal SLSS synchronization signal and the GNSS synchronization signal are compared and detected to give priority to the synchronization signal with small synchronization error.
  • performing synchronization error detection on the optimal SLSS synchronization signal and the GNSS synchronization signal respectively to determine the optimal synchronization signal includes:
  • the time domain positions of the two synchronization errors are detected to determine the optimal synchronization signal according to the detection results.
  • the IoV terminal calculates the difference between the clock corresponding to the optimal SLSS synchronization signal and its own synchronization clock to obtain the SLSS synchronization error. At the same time, the IoV terminal calculates the difference between the GPS timing corresponding to the GNSS synchronization signal and its own synchronization clock. difference to get the GNSS synchronization error. Compare the SLSS synchronization error with the GNSS synchronization error, and give priority to the synchronization error with the smaller value.
  • the detection of the time domain positions of the two synchronization errors to determine the optimal synchronization signal according to the detection results includes:
  • a cyclic prefix when the IoV terminal sends a signal, a cyclic prefix will be set in the OFDM symbol, and some positions in the cyclic prefix are no ISIS (Inter-Symbol Interference, inter-symbol interference) areas, that is, no interference areas, such as shown in Figure 4.
  • the interference-free area is an error-tolerant area. If the time-domain position of the synchronization error falls into the non-interference area, the quasi-timing synchronization will not affect the transmission and reception of the IoV terminal. If the time-domain position of the synchronization error falls within the cyclic prefix Outside the interference-free area, the timing synchronization is invalid, which directly causes inter-symbol interference. Therefore, after calculating the synchronization error of the two synchronization signals, it is necessary to detect the time domain position of the synchronization error, and it is preferable to detect the synchronization error with a small value.
  • the priority is to detect whether the time domain position of the SLSS synchronization error is located in the non-interference area. If so, the optimal SLSS synchronization signal is used as the optimal synchronization signal of the IoV terminal, and there is no need to detect GNSS again. Synchronization error; if not, continue to detect whether the time domain position of the GNSS synchronization error is located in the non-interference area, if so, use the GNSS synchronization signal as the optimal synchronization signal for the IoV terminal, if not, the synchronization fails, and the IoV terminal keeps The status quo remains unchanged.
  • Synchronization is performed according to the optimal synchronization signal.
  • the synchronization according to the optimal synchronization signal means that the IoV terminal adjusts its own synchronization clock to be consistent with the clock corresponding to the optimal synchronization signal.
  • the method further includes:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the current IoV terminal can be based on the optimal The synchronization signal is used to calibrate the crystal oscillator; if the crystal oscillator of the Internet of Vehicles terminal has been calibrated according to the PSS/SSS synchronization signal before, it is not necessary to recalibrate the crystal oscillator at present, so as to avoid the subsequent failure of the vehicle to detect any synchronization signal.
  • Networked terminals can use a crystal oscillator as a synchronization source to reduce synchronization errors.
  • the method also includes:
  • the crystal oscillator of the car networking terminal is used as a synchronization source for synchronization.
  • the crystal oscillator of the IoV terminal is calibrated when there is a synchronization signal with a high priority as much as possible, so that when the IoV terminal does not detect any synchronization signal, it can use its own crystal oscillator as a synchronization source. synchronization to minimize synchronization errors.
  • the synchronization method provided by the present application can obtain the GNSS synchronization signal when the IoV terminal detects at least one SLSS synchronization signal, and perform synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal respectively, so as to determine the most
  • the optimal synchronization signal is synchronized according to the optimal synchronization signal to avoid accumulating synchronization errors, thereby reducing synchronization errors and improving synchronization accuracy.
  • FIG. 5 is another schematic flowchart of the synchronization method provided by the embodiment of the present application.
  • the synchronization method is applied to the terminal of the Internet of Vehicles, and the specific process of the synchronization method may be as follows:
  • the Internet of Vehicles terminal A detects all the synchronization signals around it.
  • IoV terminal A does not detect the PSS/SSS synchronization signal sent by the base station, but when it detects the SLSS synchronization signal sent by IoV terminal B, IoV terminal C, and IoV terminal D, it can obtain the GNSS synchronization signal sent by GNSS .
  • the priority of the SLSS synchronization signal sent by the Internet of Vehicles terminals B and C is 1, and the priority of the SLSS synchronization signal sent by the Internet of Vehicles terminal D is 2.
  • the priority of the SLSS synchronization signal sent by the Internet of Vehicles terminals B and C is the same, which is 1, but the signal strength of the Internet of Vehicles terminal B is greater than that of the Internet of Vehicles terminal C, so the SLSS synchronization signal sent by the Internet of Vehicles terminal B is selected. is the optimal SLSS synchronization signal.
  • the synchronization error corresponding to the SLSS synchronization signal is greater than the synchronization error corresponding to the GNSS synchronization signal.
  • step 207 Detect whether the time domain position of the smallest synchronization error among the two synchronization errors is located in the non-interference area of the cyclic prefix of the IoV terminal, if so, go to step 207, if not, go to step 208.
  • the synchronization error corresponding to the GNSS synchronization signal is located in the non-interference area of the cyclic prefix of the IoV terminal A.
  • the GNSS synchronization signal is used as the optimal synchronization signal of the Internet of Vehicles terminal A, and there is no need to detect the optimal SLSS synchronization signal.
  • step 209 Detect whether the time domain position of the largest synchronization error among the two synchronization errors is located in the non-interference area of the cyclic prefix of the IoV terminal, if so, perform step 209, if not, the synchronization fails.
  • the synchronization error corresponding to the GNSS synchronization signal is outside the non-interference area of the cyclic prefix of the IoV terminal A, continue to detect whether the time domain position of the optimal SLSS synchronization signal is located in the non-interference area of the cyclic prefix of the IoV terminal A.
  • the optimal SLSS synchronization signal is used as the optimal synchronization signal of the Internet of Vehicles terminal A.
  • the IoV terminal A when the optimal synchronization signal is the GNSS synchronization signal, the IoV terminal A performs synchronization according to the GNSS synchronization signal; when the optimal synchronization signal is the SLSS synchronization signal, the IoV terminal A performs synchronization according to the SLSS synchronization signal.
  • the IoV terminal A calibrates the crystal oscillator according to the GNSS synchronization signal; when the optimal synchronization signal is the SLSS synchronization signal, the IoV terminal A calibrates the crystal oscillator according to the SLSS synchronization signal device.
  • the IoV terminal A detects the PSS/SSS synchronization signal sent by the base station E, regardless of whether it detects the SLSS signal sent by other IoV terminals, it performs synchronization according to the PSS/SSS synchronization signal. At the same time, the IoV terminal A calibrates the crystal oscillator according to the PSS/SSS synchronization signal.
  • the pre-calibrated crystal oscillator is used as the synchronization source for synchronization.
  • the embodiments of the present application effectively reduce the synchronization error of the Internet of Vehicles terminal, and improve the clock synchronization accuracy.
  • this embodiment will be further described from the perspective of a synchronization device, and the synchronization device may be integrated into a terminal of the Internet of Vehicles.
  • FIG. 6 specifically describes the synchronization apparatus provided by the embodiment of the present application.
  • the synchronization apparatus may include: a detection module 31 , an acquisition module 32 , a determination module 33 , and a synchronization module 34 .
  • the detection module 31 is used to detect the synchronization signal.
  • the IoV terminal detects the synchronization signal around it. If the IoV terminal is within the coverage of the base station, the IoV terminal can detect the synchronization signal sent by the base station, and the synchronization signal sent by the base station is PSS or SSS. If the IoV terminal is outside the coverage of the base station, and the IoV terminal can detect the synchronization signal, the synchronization signal detected by the IoV terminal is the SLSS sent by other IoV terminals. In addition, IoV terminals located outside the coverage area of the base station may not detect any synchronization signals.
  • the acquiring module 32 is configured to acquire the GNSS synchronization signal when at least one SLSS synchronization signal is detected.
  • the IoV terminal does not detect the PSS/SSS synchronization signal sent by the base station, but only detects the SLSS synchronization signal sent by other IoV terminals. In order to avoid the priority value of the SLSS synchronization signal being too large, the priority If it is too low, the accumulated synchronization error is too large, so the GNSS synchronization signal is introduced.
  • the GNSS module of the IoV terminal can receive the synchronization signal sent by the GNSS, that is, the GNSS synchronization signal. That is to say, when the IoV terminal cannot be directly synchronized with the base station, the GNSS synchronization signal is used to select the optimal synchronization signal of the IoV terminal to reduce the synchronization error of the IoV terminal.
  • the determining module 33 is configured to perform synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal, respectively, to determine an optimal synchronization signal.
  • the IoV terminal compares and detects the SLSS synchronization signal received from other IoV terminals and the GNSS synchronization signal obtained from the GNSS.
  • the synchronization signal with small synchronization error is given priority.
  • the synchronization module 34 is configured to perform synchronization according to the optimal synchronization signal.
  • the synchronization according to the optimal synchronization signal means that the IoV terminal adjusts its own synchronization clock to be consistent with the clock corresponding to the optimal synchronization signal.
  • the determining module 33 is specifically configured to:
  • the determining module 33 is specifically configured to:
  • the SLSS synchronization signal with the highest signal strength is selected from the SLSS synchronization signals with the highest priority as the optimal SLSS synchronization signal.
  • the determining module 33 is specifically configured to:
  • the time domain positions of the two synchronization errors are detected to determine the optimal synchronization signal according to the detection results.
  • the determining module 33 is specifically configured to:
  • the apparatus further includes a calibration module 35, and the calibration module 35 is specifically configured to:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the apparatus further includes a signal synchronization module 36, and the signal synchronization module 36 is specifically configured to:
  • the crystal oscillator of the connected car terminal is calibrated.
  • the apparatus further includes a synchronization source determination module 37, and the synchronization source determination module 37 is specifically configured to:
  • the crystal oscillator of the car networking terminal is used as a synchronization source for synchronization.
  • the synchronization device provided by the present application can obtain the GNSS synchronization signal when the IoV terminal detects at least one SLSS synchronization signal, and perform synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal, so as to determine the optimal
  • the synchronization signal is synchronized according to the optimal synchronization signal to avoid accumulating synchronization errors, thereby reducing synchronization errors and improving synchronization accuracy.
  • an embodiment of the present application further provides a vehicle networking terminal.
  • the Internet of Vehicles terminal 400 includes a processor 401 and a memory 402 .
  • the processor 401 is electrically connected to the memory 402 .
  • the processor 401 is the control center of the mobile terminal 400, and uses various interfaces and lines to connect various parts of the entire Internet of Vehicles terminal, and executes by running or loading the application program stored in the memory 402 and calling the data stored in the memory 402. Various functions of the Internet of Vehicles terminal and processing data, so as to conduct overall monitoring of the Internet of Vehicles terminal.
  • the detection module 31 , the acquisition module 32 , the determination module 33 and the synchronization module 34 shown in FIG. 6 may be application programs stored in the memory 402 .
  • the processor 401 in the IoV terminal 400 runs the detection module 31 , the acquisition module 32 , the determination module 33 and the synchronization module 34 stored in the memory 402 , thereby realizing various functions.
  • the detection module 31 is executed by the processor 401, it is used to detect the synchronization signal.
  • the acquiring module 32 is executed by the processor 401, it is configured to acquire the GNSS synchronization signal when at least one SLSS synchronization signal is detected.
  • the determining module 33 When the determining module 33 is executed by the processor 401, it is configured to perform synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal, respectively, to determine an optimal synchronization signal.
  • the synchronization module 34 When the synchronization module 34 is executed by the processor 401, it is used for synchronization according to the optimal synchronization signal.
  • FIG. 8 is a schematic structural diagram of an Internet of Vehicles terminal provided by an embodiment of the present application.
  • the IoV terminal 300 may include an RF circuit 310 , a memory 320 including one or more computer-readable storage media, an input unit 330 , a display unit 340 , a sensor 350 , an audio circuit 360 , a speaker 361 , a microphone 362 , and a transmission module 370 , including a processor 380 with one or more processing cores, a power supply 390 and other components.
  • a processor 380 with one or more processing cores, a power supply 390 and other components.
  • the RF circuit 310 is used for receiving and sending electromagnetic waves, realizing mutual conversion between electromagnetic waves and electrical signals, so as to communicate with a communication network or other devices.
  • RF circuitry 310 may include various existing circuit elements for performing these functions, eg, antennas, cellular communication radio frequency transceivers, millimeter wave radio frequency transceivers, WIFI/BT transceivers, GPS transceivers, digital signal processors, Encryption/decryption chips, Subscriber Identity Module (SIM) cards, memory, and more.
  • the RF circuit 310 may communicate with various networks such as the Internet, an intranet, a wireless network, or with other devices over a wireless network.
  • the aforementioned wireless network may include a cellular telephone network, a wireless local area network, or a metropolitan area network.
  • the above-mentioned wireless network can use various communication standards, protocols and technologies, including but not limited to Global System for Mobile Communication (GSM), Enhanced Data GSM Environment (EDGE), Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA), Code Division Multiple Access (Code Division Access, CDMA), Time Division Multiple Access (TDMA), Wireless Fidelity (Wireless Fidelity, Wi- Fi) (e.g.
  • IEEE 802.11a Institute of Electrical and Electronics Engineers standard IEEE 802.11a, IEEE 802.11b, IEEE802.11g and/or IEEE 802.11n
  • VoIP Voice over Internet Protocol
  • Wi-Max Worldwide Interoperability for Microwave Access
  • the memory 320 may be used to store software programs and modules, and the processor 380 executes various functional applications and data processing by running the software programs and modules stored in the memory 320 .
  • Memory 320 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory.
  • the memory 320 may further include memory disposed remotely with respect to the processor 380, and these remote memories may be connected to the connected vehicle terminal 300 through a network. Examples of such networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.
  • the input unit 330 may be used to receive input numerical or character information, and generate keyboard, mouse, joystick, optical or trackball signal input related to user settings and function control.
  • the input unit 330 may include a touch-sensitive surface 331 as well as other input devices 332 .
  • Touch-sensitive surface 331 also known as a touch display or trackpad, collects user touch operations on or near it (such as a user using a finger, stylus, etc., any suitable object or accessory on or on touch-sensitive surface 331). operation near the touch-sensitive surface 331), and drive the corresponding connection device according to a preset program.
  • the touch-sensitive surface 331 may include two parts, a touch detection device and a touch controller.
  • the touch detection device detects the user's touch orientation, detects the signal brought by the touch operation, and transmits the signal to the touch controller; the touch controller receives the touch information from the touch detection device, converts it into contact coordinates, and then sends it to the touch controller.
  • the touch-sensitive surface 331 may be implemented using various types of resistive, capacitive, infrared, and surface acoustic waves.
  • the input unit 330 may also include other input devices 332 .
  • other input devices 332 may include, but are not limited to, one or more of physical keyboards, function keys (such as volume control keys, switch keys, etc.), trackballs, mice, joysticks, and the like.
  • the display unit 340 can be used to display information input by the user or information provided to the user and various graphical user interfaces of the car networking terminal 300, which can be composed of graphics, text, icons, videos and any combination thereof.
  • the display unit 340 may include a display panel 341, and optionally, an LCD (Liquid Crystal Display, liquid crystal display), an OLED (Organic
  • the display panel 341 is configured in the form of Light-Emitting Diode, organic light emitting diode) and the like. Further, the touch-sensitive surface 331 may cover the display panel 341.
  • the touch-sensitive surface 331 When the touch-sensitive surface 331 detects a touch operation on or near it, it transmits it to the processor 380 to determine the type of the touch event, and then the processor 380 determines the type of the touch event according to the touch event. Type provides corresponding visual output on display panel 341 .
  • the touch-sensitive surface 331 and the display panel 341 are implemented as two separate components to realize the input and output functions, in some embodiments, the touch-sensitive surface 331 and the display panel 341 may be integrated to realize the input and output functions.
  • the IoV terminal 300 may further include at least one sensor 350, such as a light sensor, a motion sensor, and other sensors.
  • the light sensor may include an ambient light sensor and a proximity sensor, wherein the ambient light sensor may adjust the brightness of the display panel 341 according to the brightness of the ambient light, and the proximity sensor may close the display panel when the car networking terminal 300 is moved to the ear 341 and/or backlight.
  • the gravitational acceleration sensor can detect the magnitude of acceleration in all directions (usually three axes), and can detect the magnitude and direction of gravity when it is stationary.
  • the audio circuit 360 , the speaker 361 and the microphone 362 can provide an audio interface between the user and the connected car terminal 300 .
  • the audio circuit 360 can transmit the received audio data converted electrical signal to the speaker 361, and the speaker 361 converts it into a sound signal for output; on the other hand, the microphone 362 converts the collected sound signal into an electrical signal, which is converted by the audio circuit 360 After receiving, it is converted into audio data, and then the audio data is output to the processor 380 for processing, and then sent to, for example, another terminal through the RF circuit 310, or the audio data is output to the memory 320 for further processing.
  • the audio circuit 360 may also include an earplug jack to provide communication between the peripheral headset and the connected car terminal 300 .
  • the IoV terminal 300 can help users to send and receive emails, browse web pages, access streaming media, etc. through the transmission module 370 (eg, a WIFI module), and it provides users with wireless broadband Internet access.
  • FIG. 8 shows the transmission module 370, it can be understood that it does not belong to the necessary structure of the Internet of Vehicles terminal 300, and can be completely omitted as required within the scope of not changing the essence of the invention.
  • the processor 380 is the control center of the terminal 300, using various interfaces and lines to connect various parts of the entire terminal, by running or executing the software programs and/or modules stored in the memory 320, and calling the data stored in the memory 320, Execute various functions of the Internet of Vehicles terminal 300 and process data, so as to monitor the terminal as a whole.
  • the processor 380 may include one or more processing cores; in some embodiments, the processor 380 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user interface and Applications, etc., the modem processor mainly deals with wireless communication. It can be understood that, the above-mentioned modulation and demodulation processor may not be integrated into the processor 380 .
  • the IoV terminal 300 also includes a power source 390 (such as a battery) for supplying power to various components.
  • the power source can be logically connected to the processor 380 through a power management system, so as to manage charging, discharging, and power management through the power management system. consumption management and other functions.
  • Power supply 390 may also include one or more DC or AC power sources, recharging systems, power failure detection circuits, power converters or inverters, power status indicators, and any other components.
  • the Internet of Vehicles terminal 300 may further include a camera (eg, a front camera, a rear camera), a Bluetooth module, and the like, which will not be repeated here.
  • the display unit of the Internet of Vehicles terminal is a touch screen display, and the Internet of Vehicles terminal further includes a memory 320.
  • the detection module 31, the acquisition module 32, the determination module 33 and the synchronization module 34 shown in FIG. 6 may be stored in applications in memory 320.
  • the processor 380 in the IoV terminal 300 runs the detection module 31 , the acquisition module 32 , the determination module 33 and the synchronization module 34 stored in the memory 320 , thereby realizing various functions.
  • the detection module 31 When the detection module 31 is executed by the processor 380, it is used to detect the synchronization signal.
  • the acquisition module 32 is executed by the processor 380, it is configured to acquire the GNSS synchronization signal when at least one SLSS synchronization signal is detected.
  • the determining module 33 is executed by the processor 380, it is configured to perform synchronization error detection on the at least one SLSS synchronization signal and the GNSS synchronization signal respectively, so as to determine an optimal synchronization signal.
  • the synchronization module 34 When the synchronization module 34 is executed by the processor 380, it is used for synchronization according to the optimal synchronization signal.
  • the above modules can be implemented as independent entities, or can be arbitrarily combined to be implemented as the same or several entities.
  • the specific implementation of the above modules can refer to the previous method embodiments, which will not be repeated here.
  • the embodiments of the present invention provide a storage medium, in which a plurality of instructions are stored, and the instructions can be loaded by a processor to execute steps in any synchronization method provided by the embodiments of the present invention.
  • the storage medium may include: Read Only Memory (ROM, Read Only Memory) Memory), random access memory (RAM, Random Access Memory), disk or CD, etc.

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Abstract

本申请公开了一种同步方法、车联网终端及存储介质。所述方法应用于车联网终端，所述方法包括：检测同步信号；在检测到至少一个SLSS同步信号时，获取GNSS同步信号；分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；根据所述最优同步信号进行同步。

Description

同步方法、车联网终端及存储介质
本申请要求于2020年10月27日提交中国专利局、申请号为202011162180.5、发明名称为“同步方法、装置及存储介质”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种同步方法、车联网终端及存储介质。
 背景技术
车联网（Vehicle to X，V2X）是5G中的重要应用场景，V2X采用了ProSe（近距离通信）技术中的SideLink（边缘连接）技术，实现车辆网终端之间的直接通信。SideLink基于5G空口NR的技术（NR V2X），满足V2X需求的低时延、高可靠性、高速率标准。
NR对时频偏同步有很高要求，即要求频率、相位、时域的同步，而三种同步都必须依赖于时域同步。在SideLink同步的场景中，与基站直接连接的车联网终端，接收基站发送的同步信号进行同步；不与基站直接连接的车联网终端，则根据其他车联网终端发送的SLSS信号进行同步，若车联网终端按照这种链式同步下去，会扩大链式累积误差，从而降低车联网终端同步的准确性。
 技术问题
本申请实施例提供一种同步方法、车联网终端及存储介质，能够降低车联网终端的同步误差，提高同步准确性。
 技术解决方案
第一方面，本申请实施例提供了一种同步方法，应用于车联网终端，所述方法包括：
检测同步信号；
在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
根据所述最优同步信号进行同步。
在本申请一些实施例中，所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，具体包括：
从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
在本申请一些实施例中，所述从所述至少一个SLSS同步信号中选取最优SLSS同步信号，具体包括：
从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
在本申请一些实施例中，所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，具体包括：
分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
在本申请一些实施例中，所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号，具体包括：
检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
在本申请一些实施例中，所述方法还包括：
根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
在本申请一些实施例中，所述方法还包括：
在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；
根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
在本申请一些实施例中，所述方法还包括：
在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
第二方面，本申请实施例还提供了一种同步装置，应用于车联网终端，所述装置包括：
检测模块，用于检测同步信号；
获取模块，用于在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
确定模块，用于分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；以及，
同步模块，用于根据所述最优同步信号进行同步。
第三方面，本申请实施例还提供了一种计算机可读存储介质，所述存储介质中存储有多条指令，所述指令适于由处理器加载以执行以下步骤：
检测同步信号；
在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
根据所述最优同步信号进行同步。
在本申请一些实施例中，所述处理器在执行所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
在本申请一些实施例中，所述处理器在执行所述从所述至少一个SLSS同步信号中选取最优SLSS同步信号时，具体执行以下步骤：
从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
在本申请一些实施例中，所述处理器在执行所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
在本申请一些实施例中，所述处理器在执行所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号时，具体执行以下步骤：
检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
在本申请一些实施例中，所述处理器还执行以下步骤：
根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
在本申请一些实施例中，所述处理器还执行以下步骤：
在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；
根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
在本申请一些实施例中，所述处理器还执行以下步骤：
在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
第四方面，本申请还提供一种车联网终端，包括处理器和存储器，所述处理器与所述存储器电性连接，所述存储器用于存储指令和数据，所述处理器用于执行如下步骤：
检测同步信号；
在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
根据所述最优同步信号进行同步。
在本申请一些实施例中，所述处理器在执行所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
在本申请一些实施例中，所述处理器在执行所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
在本申请一些实施例中，所述处理器在执行所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号时，具体执行以下步骤：
检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
 有益效果
本申请提供的同步方法、车联网终端及存储介质，能够在车联网终端检测到至少一个SLSS同步信号时，获取GNSS同步信号，并分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，根据最优同步信号进行同步，避免累积同步误差，从而降低同步误差，提高同步的准确性。
 附图说明
下面结合附图，通过对本申请的具体实施方式详细描述，将使本申请的技术方案及其它有益效果显而易见。
图1为本申请实施例提供的车联网系统的结构示意图；
图2为本申请实施例提供的车联网系统的另一结构示意图；
图3为本申请实施例提供的同步方法的流程示意图；
图4为本申请实施例提供的同步方法中车联网终端所发送信号的循环前缀示意图；
图5为本申请实施例提供的同步方法的另一流程示意图；
图6为本申请实施例提供的同步装置的结构示意图；
图7为本申请实施例提供的车联网终端的结构示意图；
图8为本申请实施例提供的车联网终端的另一结构示意图。
 本发明的实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
如图1所示，图1是车联网系统的结构示意图。车联网的环境由于网络覆盖的不同，分为三种情况，即网络覆盖区、无网络覆盖区和部分网络覆盖区，SideLink的PC5接口在这三种情况下都可以使用，但NR UU接口在无网络覆盖区不存在连接，在部分网络覆盖区也可能不存在连接。因此，如图1所示，车联网终端12位于网络覆盖区，基站（qNodeB）11通过NR UU与车联网终端12连接，车辆网终端13位于无网络覆盖区，基站11与车联网终端13无法连接，而车辆网终端12可以通过SideLink与车辆网终端13连接。
两个车联网终端之间的直接通信，使这两个车联网终端构成一组D2D（device to device）终端。如图2所示，在D2D终端23中，两个车联网终端均位于基站21的覆盖范围内；在D2D终端24中，一个车联网终端位于基站21的覆盖范围内，另一个车联网终端位于基站覆盖范围外；在D2D终端25中，一个车联网终端位于基站21的覆盖范围内，另一个车联网终端位于基站22的覆盖范围内；在D2D终端26中，另个车联网终端均位于基站覆盖范围外。
如图3所示，图3是本申请实施例提供的同步方法的流程示意图，该同步方法应用于车联网终端，该同步方法的具体流程可以如下：
101．检测同步信号。
本申请实施例中，车联网终端对其周围的同步信号进行检测。若车联网终端位于基站的覆盖范围内，则车联网终端可以检测到基站发送的同步信号，基站发送的同步信号为PSS（Primary Synchronization Signal，主同步信号）或SSS（Secondary Synchronization Signal，辅同步信号）。例如，图2中构成D2D终端23的两个车辆网终端均可以检测到基站21发送的PSS/SSS同步信号，D2D终端25中位于基站21覆盖范围内的车联网终端可以检测到基站21发送的PSS/SSS同步信号，而位于基站22覆盖范围内的车联网终端可以检测到基站22发送的PSS/SSS同步信号。
若车联网终端位于基站的覆盖范围外，且车联网终端可以检测到同步信号，则车联网终端检测到的同步信号为其他车联网终端发送的SLSS（SideLink Synchronization Signal，SideLink同步信号）。例如，图2中D2D终端24中位于基站覆盖范围外的车联网终端可以检测到另一个车联网终端发送的SLSS同步信号。另外，位于基站覆盖范围外的车联网终端还可能检测不到任何同步信号，例如，图2中构成D2D终端26的两个车联网终端。
基站发送的PSS/SSS同步信号的优先级最高，可以设置为0。所述方法还包括：在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
需要说明的是，若车联网终端检测到基站发送的PSS/SSS同步信号，则直接根据该PSS/SSS同步信号进行时钟同步，即将基站作为同步源。同时，车联网终端根据该PSS/SSS同步信号对自身的晶体振荡器进行校准，以避免后续无法检测到任何同步信号时，能够将晶体振荡器作为同步源，减小同步误差。
另外，该车联网终端向外发送SLSS同步信号，并设置该SLSS同步信号的优先级为1，优先级的数值越大，则优先级越低，即该SLSS同步信号的优先级低于PSS/SSS同步信号的优先级。若其他车联网终端能够检测到的同步信号中优先级最高为1，则其他车联网终端向外发送的SLSS同步信号的优先级设置为2，以此类推，若一个车联网终端A能够检测到的同步信号中优先级最高为n，则该车联网终端A向外发送的SLSS同步信号的优先级设置为n+1，n≥0。
102．在检测到至少一个SLSS同步信号时，获取GNSS同步信号。
本申请实施例中，车联网终端未检测到基站发送的PSS/SSS同步信号，只检测到其他车联网终端发送的SLSS同步信号，为了避免该SLSS同步信号的优先级数值过大，即优先级过低，同步累积误差过大，因此引入GNSS（Global Navigation Satellite System，全球卫星导航系统）同步信号。
车联网终端的GNSS模块可以接收GNSS发送的同步信号，即GNSS同步信号。也就是说，在车联网终端不能与基站直接同步时，会借助GNSS同步信号来选取车联网终端的最优同步信号，以减小车联网终端的同步误差。
103．分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
本申请实施例中，车联网终端将从其他车联网终端处接收到的SLSS同步信号与从GNSS处获取的GNSS同步信号进行比较检测，为了提高比较检测效率，进而提高处理速度，可以从接收到的SLSS同步信号中选取一个最优的SLSS同步信号，再与GNSS同步信号进行比较检测。
具体地，步骤103中的所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，包括：
从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
其中，最优SLSS同步信号可以从优先级和信号强度两方面进行考虑。具体地，所述从所述至少一个SLSS同步信号中选取最优SLSS同步信号，包括：
从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
需要说明的是，车联网终端在接收到其他车联网终端发送的SLSS同步信号后，可以识别SLSS同步信号对应的优先级数值，从接收到的所有SLSS同步信号中选取优先级数值最小（即优先级最高）的SLSS同步信号。若选取的优先级数值最小的SLSS同步信号只有一个，则将该SLSS同步信号作为最优SLSS同步信号；若选取的优先级数值最小的SLSS同步信号仍有多个，则继续比较选取的多个SLSS同步信号的信号强度，以从中选取信号强度最高的SLSS信号作为最优SLSS同步信号。
在选取最优SLSS同步信号后，将最优SLSS同步信号与GNSS同步信号进行比较检测，以优先考虑同步误差小的同步信号。具体地，所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，包括：
分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
需要说明的是，车联网终端计算最优SLSS同步信号对应的时钟与自身同步时钟之前的差值，得到SLSS同步误差，同时车联网终端计算GNSS同步信号对应的GPS授时与自身同步时钟之间的差值，得到GNSS同步误差。比较SLSS同步误差与GNSS同步误差的大小，优先考虑数值小的同步误差。
具体地，所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号，包括：
检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端的循环前缀的无干扰区；
若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端的循环前缀的无干扰区；
若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
需要说明的是，车联网终端在发送信号时，会在OFDM符号中设置循环前缀，而循环前缀中有部分位置为无ISIS（Inter-Symbol Interference，码间干扰）区，即无干扰区，如图4所示。该无干扰区为误差容忍区，若同步误差的时域位置落入该无干扰区，为准定时同步，不会影响车联网终端的发送和接收，若同步误差的时域位置落入循环前缀的无干扰区之外，则为无效定时同步，直接引发符号间干扰。因此，在计算出两个同步信号的同步误差后，还需检测同步误差的时域位置，优选数值小的同步误差进行检测。
例如，若SLSS同步误差小于GNSS同步误差，则优先检测SLSS同步误差的时域位置是否位于无干扰区，若是，则将最优SLSS同步信号作为车联网终端的最优同步信号，无需再检测GNSS同步误差；若否，则继续检测GNSS同步误差的时域位置是否位于无干扰区，若是，则将GNSS同步信号作为车联网终端的最优同步信号，若否，则同步失败，车联网终端保持原状不变。
104．根据所述最优同步信号进行同步。
本申请实施例中，根据最优同步信号进行同步是指车联网终端将自身同步时钟调整为与最优同步信号对应的时钟相一致。
在车联网终端进行同步后，所述方法还包括：
根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
需要说明的是，若车联网终端之前未接收到基站发送的PSS/SSS同步信号，即车联网终端的晶体振荡器之前未根据PSS/SSS同步信号进行校准，则当前车联网终端可以根据最优同步信号，对晶体振荡器进行校准；若车联网终端的晶体振荡器之前已根据PSS/SSS同步信号进行校准，则当前无需再校准晶体振荡器，以避免后续无法检测到任何同步信号时，车联网终端能够将晶体振荡器作为同步源，减小同步误差。
进一步地，所述方法还包括：
在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
需要说明的是，车联网终端的晶体振荡器在尽可能有高优先级的同步信号时进行校准，以便在车联网终端未检测到任何同步信号时，能够将自身的晶体振荡器作为同步源进行同步，以尽可能减小同步误差。
由上述可知，本申请提供的同步方法，能够在车联网终端检测到至少一个SLSS同步信号时，获取GNSS同步信号，并分别对至少一个SLSS同步信号和GNSS同步信号进行同步误差检测，以确定最优同步信号，根据最优同步信号进行同步，避免累积同步误差，从而降低同步误差，提高同步的准确性。
如图5所示，图5是本申请实施例提供的同步方法的另一流程示意图，该同步方法应用于车联网终端，该同步方法的具体流程可以如下：
201.检测同步信号。
例如，车联网终端A对周围的所有同步信号进行检测。
202.在检测到至少一个SLSS同步信号时，获取GNSS同步信号。
例如，车联网终端A未检测到基站发送的PSS/SSS同步信号，但检测到车联网终端B、车联网终端C和车联网终端D发送的SLSS同步信号时，可以获取GNSS发送的GNSS同步信号。
203.从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号。
例如，在车联网终端A检测到的SLSS同步信号中，车联网终端B和C发送的SLSS同步信号的优先级为1，车联网终端D发送的SLSS同步信号的优先级为2，则选取车联网终端B和C发送的SLSS同步信号。
204.从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
例如，车联网终端B和C发送的SLSS同步信号的优先级相同，均为1，但车联网终端B的信号强度大于车联网终端C的信号强度，从而选取车联网终端B发送的SLSS同步信号为最优SLSS同步信号。
205.分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差。
例如，通过计算，得到SLSS同步信号对应的同步误差大于GNSS同步信号对应的同步误差。
206.检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端的循环前缀的无干扰区，若是，则执行步骤207，若否，则执行步骤208。
例如，检测GNSS同步信号对应的同步误差是否位于车联网终端A的循环前缀的无干扰区。
207.确定所述最小同步误差对应的同步信号为所述最优同步信号。
例如，若GNSS同步信号对应的同步误差位于车联网终端A的循环前缀的无干扰区，则将GNSS同步信号作为车联网终端A的最优同步信号，无需再检测最优SLSS同步信号。
208.检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端的循环前缀的无干扰区，若是，则执行步骤209，若否，则同步失败。
例如，若GNSS同步信号对应的同步误差位于车联网终端A的循环前缀的无干扰区外，则继续检测最优SLSS同步信号的时域位置是否位于车联网终端A的循环前缀的无干扰区。
209.确定所述最大同步误差对应的同步信号为所述最优同步信号。
例如，若最优SLSS同步信号的时域位置位于车联网终端A的循环前缀的无干扰区，则将最优SLSS同步信号作为车联网终端A的最优同步信号。
210.根据所述最优同步信号进行同步。
例如，在最优同步信号为GNSS同步信号时，车联网终端A根据该GNSS同步信号进行同步；在最优同步信号为SLSS同步信号时，车联网终端A根据该SLSS同步信号进行同步。
211.根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
例如，在最优同步信号为GNSS同步信号时，车联网终端A根据该GNSS同步信号校准晶体振荡器；在最优同步信号为SLSS同步信号时，车联网终端A根据该SLSS同步信号校准晶体振荡器。
212.在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
例如，车联网终端A在检测到基站E发送的PSS/SSS同步信号时，无论是否检测到其他车联网终端发送的SLSS信号，均根据PSS/SSS同步信号进行同步。同时，车联网终端A根据PSS/SSS同步信号校准晶体振荡器。
213.在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
例如，车联网终端A未检测到基站发送的PSS/SSS同步信号，也未检测到其他车联网终端发送的SLSS同步信号，则采用预先校准过的晶体振荡器作为同步源进行同步。
本申请实施例有效降低车联网终端的同步误差，提高时钟同步精度。
根据上述实施例所描述的方法，本实施例将从同步装置的角度进一步进行描述，该同步装置可以集成车联网终端中。
请参阅图6，图6具体描述了本申请实施例提供的同步装置，该同步装置可以包括：检测模块31、获取模块32、确定模块33和同步模块34。
（1）检测模块31
检测模块31，用于检测同步信号。
本申请实施例中，车联网终端对其周围的同步信号进行检测。若车联网终端位于基站的覆盖范围内，则车联网终端可以检测到基站发送的同步信号，基站发送的同步信号为PSS或SSS。若车联网终端位于基站的覆盖范围外，且车联网终端可以检测到同步信号，则车联网终端检测到的同步信号为其他车联网终端发送的SLSS。另外，位于基站覆盖范围外的车联网终端还可能检测不到任何同步信号。
（2）获取模块32
获取模块32，用于在检测到至少一个SLSS同步信号时，获取GNSS同步信号。
本申请实施例中，车联网终端未检测到基站发送的PSS/SSS同步信号，只检测到其他车联网终端发送的SLSS同步信号，为了避免该SLSS同步信号的优先级数值过大，即优先级过低，同步累积误差过大，因此引入GNSS同步信号。
车联网终端的GNSS模块可以接收GNSS发送的同步信号，即GNSS同步信号。也就是说，在车联网终端不能与基站直接同步时，会借助GNSS同步信号来选取车联网终端的最优同步信号，以减小车联网终端的同步误差。
（3）确定模块33
确定模块33，用于分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
本申请实施例中，车联网终端将从其他车联网终端处接收到的SLSS同步信号与从GNSS处获取的GNSS同步信号进行比较检测。其中，优先考虑同步误差小的同步信号。
（4）同步模块34
同步模块34，用于根据所述最优同步信号进行同步。
本申请实施例中，根据最优同步信号进行同步是指车联网终端将自身同步时钟调整为与最优同步信号对应的时钟相一致。
在本申请的一些实施例中，所述确定模块33具体用于：
从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
在本申请的一些实施例中，所述确定模块33具体用于：
从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
在本申请的一些实施例中，所述确定模块33具体用于：
分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
在本申请的一些实施例中，所述确定模块33具体用于：
检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
在本申请的一些实施例中，所述装置还包括校准模块35，所述校准模块35具体用于：
根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
在本申请的一些实施例中，所述装置还包括信号同步模块36，所述信号同步模块36具体用于：
在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；
根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
在本申请的一些实施例中，所述装置还包括同步源确定模块37，所述同步源确定模块37具体用于：
在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
由上述可知，本申请提供的同步装置，能够在车联网终端检测到至少一个SLSS同步信号时，获取GNSS同步信号，并对至少一个SLSS同步信号与GNSS同步信号进行同步误差检测，以确定最优同步信号，根据最优同步信号进行同步，避免累积同步误差，从而降低同步误差，提高同步的准确性。
另外，本申请实施例还提供一种车联网终端。如图7所示，车联网终端400包括处理器401、存储器402。其中，处理器401与存储器402电性连接。
处理器401是移动终端400的控制中心，利用各种接口和线路连接整个车联网终端的各个部分，通过运行或加载存储在存储器402内的应用程序，以及调用存储在存储器402内的数据，执行车联网终端的各种功能和处理数据，从而对车联网终端进行整体监控。
在本实施例中，图6所示的检测模块31、获取模块32、确定模块33和同步模块34可以是存储在存储器402中的应用程序。车联网终端400中的处理器401运行存储在存储器402中的检测模块31、获取模块32、确定模块33和同步模块34，从而实现各种功能。当检测模块31被处理器401执行时，用于检测同步信号。当获取模块32被处理器401执行时，用于在检测到至少一个SLSS同步信号时，获取GNSS同步信号。当确定模块33被处理器401执行时，用于分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。当同步模块34被处理器401执行时，用于根据所述最优同步信号进行同步。
请参阅图8，图8为本申请实施例提供的车联网终端的结构示意图。该车联网终端300可以包括RF电路310、包括有一个或一个以上计算机可读存储介质的存储器320、输入单元330、显示单元340、传感器350、音频电路360、扬声器361、传声器362、传输模块370、包括有一个或者一个以上处理核心的处理器380、以及电源390等部件。本领域技术人员可以理解，图8中示出的车联网终端结构并不构成对车联网终端的限定，可以包括比图示更多或更少的部件，或者组合某些部件，或者不同的部件布置。
RF电路310用于接收以及发送电磁波，实现电磁波与电信号的相互转换，从而与通讯网络或者其他设备进行通讯。RF电路310可包括各种现有的用于执行这些功能的电路元件，例如，天线、蜂窝通信射频收发器、毫米波射频收发器、WIFI/BT收发器、GPS收发器、数字信号处理器、加密/解密芯片、用户身份模块（SIM）卡、存储器等等。RF电路310可与各种网络如互联网、企业内部网、无线网络进行通讯或者通过无线网络与其他设备进行通讯。上述的无线网络可包括蜂窝式电话网、无线局域网或者城域网。上述的无线网络可以使用各种通信标准、协议及技术，包括但并不限于全球移动通信系统（Global System for Mobile Communication, GSM）、增强型移动通信技术（Enhanced Data GSM Environment, EDGE)，宽带码分多址技术（Wideband Code Division Multiple Access, WCDMA），码分多址技术（Code Division Access, CDMA）、时分多址技术（Time Division Multiple Access, TDMA），无线保真技术（Wireless Fidelity， Wi-Fi）（如美国电气和电子工程师协会标准 IEEE 802.11a， IEEE 802.11b, IEEE802.11g 和/或 IEEE 802.11n）、网络电话（Voice over Internet Protocol, VoIP）、全球微波互联接入（Worldwide Interoperability for Microwave Access， Wi-Max）、其他用于邮件、即时通讯及短消息的协议，以及任何其他合适的通讯协议，甚至可包括那些当前仍未被开发出来的协议。
存储器320可用于存储软件程序以及模块，处理器380通过运行存储在存储器320内的软件程序以及模块，从而执行各种功能应用以及数据处理。存储器320可包括高速随机存储器，还可包括非易失性存储器，如一个或者多个磁性存储装置、闪存、或者其他非易失性固态存储器。在一些实例中，存储器320可进一步包括相对于处理器380远程设置的存储器，这些远程存储器可以通过网络连接至车联网终端300。上述网络的实例包括但不限于互联网、企业内部网、局域网、移动通信网及其组合。
输入单元330可用于接收输入的数字或字符信息，以及产生与用户设置以及功能控制有关的键盘、鼠标、操作杆、光学或者轨迹球信号输入。具体地，输入单元330可包括触敏表面331以及其他输入设备332。触敏表面331，也称为触摸显示屏或者触控板，可收集用户在其上或附近的触摸操作（比如用户使用手指、触笔等任何适合的物体或附件在触敏表面331上或在触敏表面331附近的操作），并根据预先设定的程式驱动相应的连接装置。可选的，触敏表面331可包括触摸检测装置和触摸控制器两个部分。其中，触摸检测装置检测用户的触摸方位，并检测触摸操作带来的信号，将信号传送给触摸控制器；触摸控制器从触摸检测装置上接收触摸信息，并将它转换成触点坐标，再送给处理器380，并能接收处理器380发来的命令并加以执行。此外，可以采用电阻式、电容式、红外线以及表面声波等多种类型实现触敏表面331。除了触敏表面331，输入单元330还可以包括其他输入设备332。具体地，其他输入设备332可以包括但不限于物理键盘、功能键（比如音量控制按键、开关按键等）、轨迹球、鼠标、操作杆等中的一种或多种。
显示单元340可用于显示由用户输入的信息或提供给用户的信息以及车联网终端300的各种图形用户接口，这些图形用户接口可以由图形、文本、图标、视频和其任意组合来构成。显示单元340可包括显示面板341，可选的，可以采用LCD(Liquid Crystal Display，液晶显示器)、OLED(Organic Light-Emitting Diode,有机发光二极管)等形式来配置显示面板341。进一步的，触敏表面331可覆盖显示面板341，当触敏表面331检测到在其上或附近的触摸操作后，传送给处理器380以确定触摸事件的类型，随后处理器380根据触摸事件的类型在显示面板341上提供相应的视觉输出。虽然在图8中，触敏表面331与显示面板341是作为两个独立的部件来实现输入和输出功能，但是在某些实施例中，可以将触敏表面331与显示面板341集成而实现输入和输出功能。
车联网终端300还可包括至少一种传感器350，比如光传感器、运动传感器以及其他传感器。具体地，光传感器可包括环境光传感器及接近传感器，其中，环境光传感器可根据环境光线的明暗来调节显示面板341的亮度，接近传感器可在车联网终端300移动到耳边时，关闭显示面板341和/或背光。作为运动传感器的一种，重力加速度传感器可检测各个方向上（一般为三轴）加速度的大小，静止时可检测出重力的大小及方向，可用于识别终端姿态的应用（比如横竖屏切换、相关游戏、磁力计姿态校准）、振动识别相关功能（比如计步器、敲击）等; 至于车联网终端300还可配置的陀螺仪、气压计、湿度计、温度计、红外线传感器等其他传感器，在此不再赘述。
音频电路360、扬声器361和传声器362，传声器362可提供用户与车联网终端300之间的音频接口。音频电路360可将接收到的音频数据转换后的电信号，传输到扬声器361，由扬声器361转换为声音信号输出；另一方面，传声器362将收集的声音信号转换为电信号，由音频电路360接收后转换为音频数据，再将音频数据输出处理器380处理后，经RF电路310以发送给比如另一终端，或者将音频数据输出至存储器320以便进一步处理。音频电路360还可能包括耳塞插孔，以提供外设耳机与车联网终端300的通信。
车联网终端300通过传输模块370（例如WIFI模块）可以帮助用户收发电子邮件、浏览网页和访问流式媒体等，它为用户提供了无线的宽带互联网访问。虽然图8示出了传输模块370，但是可以理解的是，其并不属于车联网终端300的必须构成，完全可以根据需要在不改变发明的本质的范围内而省略。
处理器380是终端300的控制中心，利用各种接口和线路连接整个终端的各个部分，通过运行或执行存储在存储器320内的软件程序和/或模块，以及调用存储在存储器320内的数据，执行车联网终端300的各种功能和处理数据，从而对终端进行整体监控。可选的，处理器380可包括一个或多个处理核心；在一些实施例中，处理器380可集成应用处理器和调制解调处理器，其中，应用处理器主要处理操作系统、用户界面和应用程序等，调制解调处理器主要处理无线通信。可以理解的是，上述调制解调处理器也可以不集成到处理器380中。
车联网终端300还包括给各个部件供电的电源390（比如电池），在一些实施例中，电源可以通过电源管理系统与处理器380逻辑相连，从而通过电源管理系统实现管理充电、放电、以及功耗管理等功能。电源390还可以包括一个或一个以上的直流或交流电源、再充电系统、电源故障检测电路、电源转换器或者逆变器、电源状态指示器等任意组件。
尽管未示出，车联网终端300还可以包括摄像头（如前置摄像头、后置摄像头）、蓝牙模块等，在此不再赘述。具体在本实施例中，车联网终端的显示单元是触摸屏显示器，车联网终端还包括有存储器320，图6所示的检测模块31、获取模块32、确定模块33和同步模块34可以是存储在存储器320中的应用程序。车联网终端300中的处理器380运行存储在存储器320中的检测模块31、获取模块32、确定模块33和同步模块34，从而实现各种功能。当检测模块31被处理器380执行时，用于检测同步信号。当获取模块32被处理器380执行时，用于在检测到至少一个SLSS同步信号时，获取GNSS同步信号。当确定模块33被处理器380执行时，用于分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。当同步模块34被处理器380执行时，用于根据所述最优同步信号进行同步。
具体实施时，以上各个模块可以作为独立的实体来实现，也可以进行任意组合，作为同一或若干个实体来实现，以上各个模块的具体实施可参见前面的方法实施例，在此不再赘述。
本领域普通技术人员可以理解，上述实施例的各种方法中的全部或部分步骤可以通过指令来完成，或通过指令控制相关的硬件来完成，该指令可以存储于一计算机可读存储介质中，并由处理器进行加载和执行。为此，本发明实施例提供一种存储介质，其中存储有多条指令，该指令能够被处理器进行加载，以执行本发明实施例所提供的任一种同步方法中的步骤。
其中，该存储介质可以包括：只读存储器（ROM，Read Only Memory）、随机存取记忆体（RAM，Random Access Memory）、磁盘或光盘等。
由于该存储介质中所存储的指令，可以执行本发明实施例所提供的任一种同步方法中的步骤，因此，可以实现本发明实施例所提供的任一种同步方法所能实现的有益效果，详见前面的实施例，在此不再赘述。
以上各个操作的具体实施可参见前面的实施例，在此不再赘述。
综上该，虽然本申请已以优选实施例揭露如上，但上述优选实施例并非用以限制本申请，本领域的普通技术人员，在不脱离本申请的精神和范围内，均可作各种更动与润饰，因此本申请的保护范围以权利要求界定的范围为准。

Claims (20)

  1. 一种同步方法，应用于车联网终端，所述方法包括：
    检测同步信号；
    在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
    分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
    根据所述最优同步信号进行同步。
  2. 根据权利要求1所述的同步方法，其中，所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，具体包括：
    从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
    分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
  3. 根据权利要求2所述的同步方法，其中，所述从所述至少一个SLSS同步信号中选取最优SLSS同步信号，具体包括：
    从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
    从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
  4. 根据权利要求2所述的同步方法，其中，所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号，具体包括：
    分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
    检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
  5. 根据权利要求4所述的同步方法，其中，所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号，具体包括：
    检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
    若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
  6. 根据权利要求1所述的同步方法，其中，所述方法还包括：
    根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
  7. 根据权利要求1所述的同步方法，其中，所述方法还包括：
    在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；
    根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
  8. 根据权利要求1所述的同步方法，其中，所述方法还包括：
    在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
  9. 一种计算机可读存储介质，所述存储介质中存储有多条指令，所述指令适于由处理器加载以执行以下步骤：
    检测同步信号；
    在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
    分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
    根据所述最优同步信号进行同步。
  10. 根据权利要求9所述的计算机可读存储介质，其中，所述处理器在执行所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
    从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
    分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
  11. 根据权利要求10所述的计算机可读存储介质，其中，所述处理器在执行所述从所述至少一个SLSS同步信号中选取最优SLSS同步信号时，具体执行以下步骤：
    从所述至少一个SLSS同步信号中选取优先级最高的SLSS同步信号；
    从所述优先级最高的SLSS同步信号中选取信号强度最高的SLSS同步信号，作为所述最优SLSS同步信号。
  12. 根据权利要求10所述的计算机可读存储介质，其中，所述处理器在执行所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
    分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
    检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
  13. 根据权利要求12所述的计算机可读存储介质，其中，所述处理器在执行所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号时，具体执行以下步骤：
    检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
    若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
  14. 根据权利要求9所述的计算机可读存储介质，其中，所述处理器还执行以下步骤：
    根据所述最优同步信号，校准所述车联网终端的晶体振荡器。
  15. 根据权利要求9所述的计算机可读存储介质，其中，所述处理器还执行以下步骤：
    在检测到PSS/SSS同步信号时，根据所述PSS/SSS同步信号进行同步；
    根据所述PSS/SSS同步信号，校准所述车联网终端的晶体振荡器。
  16. 根据权利要求9所述的计算机可读存储介质，其中，所述处理器还执行以下步骤：
    在未检测到同步信号时，将所述车联网终端的晶体振荡器作为同步源进行同步。
  17. 一种车联网终端，包括处理器和存储器，所述处理器与所述存储器电性连接，所述存储器用于存储指令和数据，所述处理器用于执行如下步骤：
    检测同步信号；
    在检测到至少一个SLSS同步信号时，获取GNSS同步信号；
    分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号；
    根据所述最优同步信号进行同步。
  18. 根据权利要求17所述的车联网终端，其中，所述处理器在执行所述分别对所述至少一个SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
    从所述至少一个SLSS同步信号中选取最优SLSS同步信号；
    分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号。
  19. 根据权利要求18所述的车联网终端，其中，所述处理器在执行所述分别对所述最优SLSS同步信号和所述GNSS同步信号进行同步误差检测，以确定最优同步信号时，具体执行以下步骤：
    分别计算所述最优SLSS同步信号、所述GNSS同步信号与所述车联网终端的同步时钟之间的同步误差，得到两个同步误差；
    检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号。
  20. 根据权利要求19所述的车联网终端，其中，所述处理器在执行所述检测所述两个同步误差的时域位置，以根据检测结果确定最优同步信号时，具体执行以下步骤：
    检测所述两个同步误差中的最小同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最小同步误差对应的同步信号为所述最优同步信号；
    若否，则检测所述两个同步误差中的最大同步误差的时域位置是否位于所述车联网终端所发送信号的循环前缀的无干扰区；
    若是，则确定所述最大同步误差对应的同步信号为所述最优同步信号。
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