Joint synchronization method and device for V2X, and storage medium

Abstract

The invention provides a joint synchronization method and device for V2X, and a storage medium. The method is applied to terminal equipment, and comprises the following steps: determining the position of a first sending subframe, and taking the position of a next physical subframe of the first sending subframe as an initial position; the sending subframe comprises a reserved subframe for sending an SLSS and / or a logic subframe for sending a beacon synchronization signal; starting from the initial position, performing beacon signal receiving detection and / or SLSS receiving detection on each physical subframe until the detection is passed; the beacon signal receiving detection is used for detecting whether a beacon synchronization signal exists on the physical subframe; the SLSS receiving detection is used for detecting whether an SLSS exists on the physical subframe or not; and performing synchronization according to the synchronization information carried by the detected physical subframe and a first synchronization measurement result obtained by current measurement. The two kinds of synchronization information are used for joint synchronization, so that the synchronization signal can be detected more quickly, different channel environments can be adapted, and the synchronization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a joint synchronization method, device and storage medium for V2X. Background Art

[0002] Long Time Evolution-Vehicle to everything (LTE-V2X) terminals support two synchronization methods when there is no Global Navigation Satellite System (GNSS) signal. One is the synchronization method based on the Sidelink Synchronisation Signal (SLSS) and the other is the beacon synchronization method.

[0003] The SLSS synchronization method is based on the synchronization scheme specified by the 3GPP protocol. It is synchronized through SLSS and the Physical Sidelink Broadcast Channel (PSBCH). It has disadvantages such as poor timing accuracy and long transmission cycle, resulting in low synchronization accuracy. Beacon synchronization is a synchronization scheme supplemented by the industry standard. It is synchronized through the Physical Sidelink Control Channel (PSCCH) and the Physical Sidelink Shared Channel (PSSCH). It has high timing accuracy, but also high complexity and high requirements for the channel environment. When the channel environment is poor, low synchronization accuracy or even failure to synchronize normally will occur. Summary of the invention

[0004] The present invention provides a joint synchronization method, device and storage medium for V2X, which are used to solve the technical problem of low synchronization efficiency in the prior art.

[0005] In a first aspect, the present invention provides a joint synchronization method for V2X, comprising the following steps.

[0006] Determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; Starting from the starting position, a beacon signal reception detection and / or an SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; Synchronization is performed according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

[0007] In some embodiments, the performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Before the first timer expires, performing beacon signal reception detection on each physical subframe; and / or Before the second timer expires, SLSS reception detection is performed on each physical subframe.

[0008] In some embodiments, the method further comprises: When the terminal device is turned on or starts searching for a synchronization signal, starting the first timer; When the first timer times out and no physical subframe is detected by beacon signal reception, start the second timer; and / or When the second timer times out and no physical subframe passes SLSS reception detection, the first timer is started.

[0009] In some embodiments, the method further comprises: In the case where there is a physical subframe detected by receiving a beacon signal, ending the first timer; When the first timer times out, end the first timer; In the case that there is a physical subframe detected by SLSS reception, ending the second timer; and / or When the second timer times out, the second timer is ended.

[0010] In some embodiments, the performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Beacon signal reception detection and SLSS reception detection are performed on each physical subframe.

[0011] In some embodiments, performing SLSS reception detection on each physical subframe includes: Determine whether the physical subframe is a reserved subframe for sending SLSS, and perform physical layer side link broadcast channel PSBCH decoding check on the data carried by the physical subframe; In a case where the physical subframe is a reserved subframe for sending SLSS and the PSBCH decoding check succeeds, determining that the SLSS reception detection passes; and / or When the physical subframe is not a reserved subframe for sending SLSS, or the PSBCH decoding check fails, it is determined that the SLSS reception detection fails.

[0012] In some embodiments, the determining whether the physical subframe is a reserved subframe for sending the SLSS includes: Low-pass filtering and down-sampling are performed on the data carried by the physical subframe to obtain two columns of side link primary synchronization signal PSSS symbols, two columns of side link secondary synchronization signal SSSS symbols, and three columns of physical layer side link broadcast channel PSBCH demodulation reference signal DMRS symbols; Perform correlation detection according to the PSSS symbol, the SSSS symbol and the PSBCH DMRS symbol to obtain a correlation value; When the correlation value is greater than a preset threshold, determining that the physical subframe is a reserved subframe for sending the SLSS; and / or When the correlation value is less than or equal to the preset threshold, it is determined that the physical subframe is not a reserved subframe for sending the SLSS.

[0013] In some embodiments, performing beacon signal reception detection on each physical subframe includes: Determine whether a physical side link control channel PSCCH signal carried by the physical subframe meets the beacon synchronization signal characteristics, and perform physical side link shared channel PSSCH decoding check on the data carried by the physical subframe; If the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding verification is successful, determine that the beacon signal reception detection is passed; and / or When the PSCCH signal does not conform to the beacon synchronization signal characteristics, or the PSSCH decoding check fails, it is determined that the beacon signal reception detection fails.

[0014] In some embodiments, determining the position of the first transmitted subframe includes: Detect the rising edge and falling edge of the power value of the radio frequency data; In the case where the interval time between a group of rising edges and falling edges is the length of a transmission subframe, the time domain position corresponding to the group of rising edges and falling edges is determined as the position of the first transmission subframe.

[0015] In some embodiments, when synchronization is completed, the method further includes: Determine whether a synchronization signal is received in the current physical subframe; When the current physical subframe receives a synchronization signal, the value of the first counter is cleared, and synchronization maintenance is performed based on the synchronization information carried by the synchronization signal.

[0016] In some embodiments, when the synchronization signal is a beacon synchronization signal, performing synchronization maintenance based on synchronization information carried by the synchronization signal includes: Determining whether the synchronization level in the synchronization information carried by the beacon synchronization signal is higher than or equal to the current system synchronization level; When the synchronization level in the synchronization information is higher than or equal to the current system synchronization level, updating the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and synchronizing according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result; and / or In a case where the synchronization level of the beacon synchronization signal is lower than the current system synchronization level, it is determined whether a synchronization signal is received in a next physical subframe.

[0017] In some embodiments, updating the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and performing synchronization according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result, includes: updating a timing estimate according to a timing estimate residual carried by the beacon synchronization signal and a timing estimate in the second synchronization measurement result, and updating a frequency offset estimate according to a frequency offset estimate residual carried by the beacon synchronization signal and a frequency offset estimate in the synchronization measurement result; Synchronization is performed based on the updated timing estimate, the updated frequency offset estimate, and the synchronization information carried by the beacon synchronization signal.

[0018] In some embodiments, when the synchronization level of the beacon synchronization signal is higher than or equal to the current system synchronization level, the method further includes: Determining whether the subframe number in the synchronization information is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

[0019] In some embodiments, when the synchronization signal is SLSS, the performing synchronization maintenance based on the synchronization information carried by the synchronization signal includes: Determine whether the subframe number in the synchronization information carried by the SLSS is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

[0020] In some embodiments, the method further comprises: When the subframe number in the synchronization information is not equal to the system subframe number, adding one to the value of the second counter, and determining whether the value of the second counter exceeds a second threshold value; When the value of the second counter exceeds the second threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the second counter does not exceed the second threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

[0021] In some embodiments, the method further comprises: In the case that the current physical subframe does not receive a synchronization signal, adding one to the value of the first counter, and determining whether the value of the first counter exceeds a first threshold value; When the value of the first counter exceeds the first threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the first counter does not exceed the first threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

[0022] In some embodiments, the method further comprises: Determine whether the current physical subframe is a reserved subframe; When the current physical subframe is a reserved subframe, performing a beacon signal reception detection on the current physical subframe, and when the beacon signal reception detection passes, determining that a beacon synchronization signal is received in the current physical subframe; and / or In a case where the current physical subframe is not a reserved subframe, a SLSS reception detection is performed on the current physical subframe, and in a case where the SLSS reception detection passes, it is determined that the SLSS is received in the current physical subframe.

[0023] In some embodiments, the specific steps of performing synchronization include one or more of the following: Adjust the subframe number of the current system according to the subframe number in the synchronization information; adjusting the starting position of the subframe according to the timing estimate in the synchronization measurement result; Adjust the crystal oscillator based on the frequency offset estimate from the synchronous measurement results; Adjust the UTC of the current system according to the coordinated universal time UTC in the synchronization information; Determine the synchronization level of the current system according to the synchronization level in the synchronization information; Calculating a target timing estimate based on the timing estimate residual in the synchronization information and the timing estimate in the synchronization measurement result, and adjusting the starting position of the subframe based on the target timing estimate; Calculating a target frequency offset estimate based on the frequency offset estimate residual in the synchronization information and the frequency offset estimate in the synchronization measurement result, and adjusting the crystal oscillator based on the target frequency offset estimate; and / or Leap seconds are adjusted according to the leap second indication in the sync information.

[0024] In a second aspect, the present invention provides a joint synchronization device for V2X, comprising the following modules: A first determination module is used to determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; A synchronization signal reception detection module, used to perform a beacon signal reception detection and / or an SLSS reception detection on each physical subframe starting from the starting position until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; The synchronization module is used to perform synchronization according to the synchronization information carried by the physical subframe that has been detected and the first synchronization measurement result obtained by the current measurement.

[0025] In a third aspect, the present invention provides a terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the joint synchronization method for V2X as described in the first aspect above is implemented.

[0026] In a fourth aspect, a non-transitory computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the joint synchronization method for V2X as described in the first aspect above.

[0027] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the joint synchronization method for V2X as described in the first aspect above is implemented.

[0028] The present invention provides a joint synchronization method, device and storage medium for V2X, wherein the terminal device determines the position of the first transmission subframe, and uses the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for transmitting the side link synchronization signal SLSS and / or a logical subframe for transmitting the beacon synchronization signal; starting from the starting position, a beacon signal reception detection and / or SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; synchronization is performed according to the synchronization information carried by the physical subframe that passes the detection and the first synchronization measurement result obtained by the current measurement. By using two types of synchronization information for joint synchronization, the synchronization signal can be detected faster, thereby reducing the time required for synchronization, and can adapt to various channel environments to ensure successful detection of synchronization signals at different code rates, thereby improving synchronization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is one of the flow charts of the joint synchronization method for V2X provided by the present invention.

[0031] Figure 2 This is the second flow chart of the joint synchronization method for V2X provided by the present invention.

[0032] Figure 3 It is one of the frame structure diagrams of the synchronization signal search example provided by the present invention.

[0033] Figure 4 This is the second frame structure diagram of the synchronization signal search example provided by the present invention.

[0034] Figure 5 This is the third frame structure diagram of the synchronization signal search example provided by the present invention.

[0035] Figure 6 This is the third flow chart of the joint synchronization method for V2X provided by the present invention.

[0036] Figure 7 This is the fourth frame structure diagram of the synchronization signal search example provided by the present invention.

[0037] Figure 8This is the fifth frame structure diagram of the synchronization signal search example provided by the present invention.

[0038] Fig. 9 This is the fourth flow chart of the joint synchronization method for V2X provided by the present invention.

[0039] Fig.10 It is a structural schematic diagram of a joint synchronization device for V2X provided by the present invention.

[0040] Fig.11 It is a structural schematic diagram of the terminal device provided by the present invention. DETAILED DESCRIPTION

[0041] LTE-V2X schedules transmission and reception according to subframes. The system physical subframe number is 0 to 10239. The time of each subframe is 1 millisecond. When the remainder of the physical subframe number divided by 256 is 0, it corresponds to a reserved subframe, that is, the physical subframe number corresponding to the reserved subframe is 0, 256, 512, ..., that is, there is a reserved subframe for every 256 physical subframes (256 milliseconds), and the remaining 255 physical subframes are logical subframes. The physical subframe number is 0 to 10239, the logical subframe number is 0 to 10199, and the remaining 40 subframes are reserved subframes. For example, the physical subframe number 0 corresponds to the reserved subframe, the physical subframe number 1 corresponds to the logical subframe 0, the physical subframe number 256 corresponds to the reserved subframe, the physical subframe number 257 corresponds to the logical subframe 255, and so on.

[0042] When there is no GNSS signal, the synchronization scheme of the roadside equipment includes sending SLSS synchronization signals and sending beacon synchronization signals.

[0043] The SLSS synchronization signal sending scheme is as follows: The SLSS synchronization signal is sent in each reserved subframe, that is, the transmission period of the SLSS synchronization signal is 256 milliseconds, and the SLSS occupies 6 physical resource blocks (PRBs) on a fixed basis. The SLSS synchronization signal includes the primary sidelink synchronization signal (PSSS), the secondary sidelink synchronization signal (SSSS), the PSBCH and the PSBCH demodulation reference signal (DMRS) in 14 symbols in a subframe. The information in the PSBCH includes the system bandwidth (sl-Bandwidth-r14), the TDD configuration (tdd-ConfigSL-r14), the frame number directFrameNumber-r14 (range 0 to 1023), and the subframe number directSubframeNumber-r14 (range 0 to 9) The beacon synchronization signal sending scheme is as follows: The beacon synchronization signal is sent according to the configured period T, which is sent once every 100 logical subframes by default (100 milliseconds when there is no reserved subframe in the period or 101 milliseconds when there is a reserved subframe in the period). The beacon synchronization signal occupies 50 PRBs, of which PSCCH occupies 2 PRBs and PSSCH occupies 48 PRBs. The beacon synchronization signal includes PSCCH, PSSCH, PSCCH DMRS, and PSSCH DMRS, which are in 14 symbols in one subframe.

[0044] At present, the terminal synchronization scheme only uses one synchronization signal as a synchronization scheme without GNSS. When only SLSS signal is used for synchronization, due to the small number of PRBs occupied by PSBCH and the long period, there will be shortcomings such as inaccurate timing estimation and frequency offset estimation, long synchronization time, and less system information carried. When only beacon signal is used for synchronization, due to the high modulation and code rate (MCS) of the beacon signal PSSCH, when the channel environment is poor, the timing estimation and frequency offset estimation will be inaccurate or even unable to synchronize normally. If the sending device does not support beacon signal sending, the terminal can only search for beacon signal and cannot synchronize.

[0045] Based on the above technical problems, the present invention proposes a joint synchronization method, which determines the position of the first sending subframe, and takes the position of the next physical subframe of the first sending subframe as the starting position; the sending subframe includes a reserved subframe for sending the side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; starting from the starting position, a beacon signal reception detection and / or SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; synchronization is performed according to the synchronization information carried by the physical subframe that passes the detection and the first synchronization measurement result obtained by the current measurement. By using two types of synchronization information for joint synchronization, the synchronization signal can be detected faster, thereby reducing the time required for synchronization, and can adapt to various channel environments to ensure successful detection of synchronization signals at different code rates, thereby improving synchronization efficiency.

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Figure 1 is one of the flow charts of the joint synchronization method for V2X provided by the present invention, such as Figure 1 As shown, the present invention provides a joint synchronization method for V2X, and the execution subject may be a terminal device. The method includes: Step 101, determine the position of the first sending subframe, and use the position of the next physical subframe of the first sending subframe as the starting position; the sending subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal.

[0048] Specifically, the terminal device is a device that receives synchronization signals in V2X (also known as a receiving terminal device), which may be a road side unit (RSU) or an on board unit (OBU).

[0049] The synchronization signal may be a SLSS and / or a beacon synchronization signal.

[0050] The synchronization signal is sent by other terminal devices. The terminal device that sends the synchronization signal (referred to as the sending terminal device) can be an RSU or an OBU. For example, the sending terminal device sends the beacon synchronization signal with an offset of n logical subframes and a period of m logical subframes, where n is a natural number and m is a positive integer. For another example, the sending terminal device sends the SLSS in a reserved subframe.

[0051] The transmission subframe is a subframe for transmitting synchronization signals, including a reserved subframe for transmitting SLSS and / or a logical subframe for transmitting beacon synchronization signals. The first transmission subframe refers to the first transmission subframe searched after the receiving terminal device is turned on or when searching for synchronization signals again.

[0052] The sending terminal device sends SLSS and / or beacon synchronization signals. The receiving terminal device starts to capture SLSS and beacon synchronization signals when it is turned on or searches for synchronization signals again. Specifically, it determines in turn whether each physical subframe is a sending subframe for sending synchronization signals. When the first sending subframe is determined, the first synchronization signal is captured and the position of the first sending subframe is known. At the same time, the position of each subsequent physical subframe can also be determined, and the position of the next physical subframe of the first sending subframe is used as the starting position for synchronization signal reception detection.

[0053] For example, the transmitting terminal device transmits a beacon synchronization signal with an offset of 0 logical subframes and a period of 100 logical subframes, and transmits SLSS in a reserved subframe. When the receiving terminal device is powered on or searches for the synchronization signal again (assuming the position of the physical subframe a, a is 0 when powered on, and a is a positive integer when searching for the synchronization signal again), it starts searching for SLSS and beacon synchronization signals, and determines the position of the first transmitted subframe, which may be a logical subframe for sending a beacon synchronization signal, or a reserved subframe for sending SLSS. The position of the next physical subframe of the first transmitted subframe is used as the starting position.

[0054] Step 102: Starting from the starting position, perform beacon signal reception detection and / or SLSS reception detection on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe.

[0055] Specifically, after determining the position of the first transmitted subframe, the position of the next physical subframe of the first transmitted subframe is used as the starting position, and a beacon signal reception detection and / or an SLSS reception detection are performed on each physical subframe until the detection passes. The beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe, and the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe.

[0056] For example, starting from the starting position, the beacon signal reception detection is performed on the first a physical subframes (where a is a positive integer). If the beacon signal reception detection fails, the SLSS reception detection is continued to be performed on the a+1th to a+bth physical subframes (where b is a positive integer). In this way, the beacon signal reception detection of a physical subframes and the SLSS reception detection of b physical subframes are performed alternately until the detection of a physical subframe passes and the detection is stopped.

[0057] For another example, starting from the starting position, a beacon signal reception detection is performed on the physical subframe within time t1 (where t1 is greater than 0). If the beacon signal reception detection fails, the SLSS reception detection is continued to be performed on the subsequent physical subframe within time t2 (where t2 is greater than 0). In this way, the beacon signal reception detection at time t1 and the SLSS reception detection at time t2 are performed alternately until the detection of a physical subframe passes and the detection is stopped.

[0058] For another example, starting from the starting position, beacon signal reception detection and SLSS reception detection are performed on each physical subframe simultaneously until the beacon signal reception detection or SLSS reception detection of a physical subframe passes, and then the detection is stopped.

[0059] Step 103: Perform synchronization according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

[0060] Specifically, after a beacon signal reception detection or SLSS reception detection is passed on a physical subframe, the synchronization information carried by the physical subframe that passes the detection is obtained, such as the subframe number, UTC time, timing estimation residual and / or frequency offset estimation residual, etc., and the first synchronization measurement result obtained by the physical layer measurement is obtained, the first synchronization measurement result includes timing estimation and frequency offset estimation, and then synchronization is performed according to the synchronization information and the first synchronization measurement result.

[0061] For example, if a beacon signal reception detection is performed on a physical subframe, the synchronization information such as the subframe number, UTC time, timing estimation residual, and frequency offset estimation residual carried by the PSSCH on the physical subframe that passes the detection is obtained. Assume that the subframe number is 0, the UTC time is 0:00 on January 1, 2024, the timing estimation residual is 10us, and the frequency offset estimation residual is 50Hz. The timing estimation and frequency offset estimation obtained by the current measurement are obtained. Assume that the timing estimation is 200us and the frequency offset estimation is 600Hz. The negotiable timing estimation has a positive value indicating a timing delay, a negative value indicating a timing advance, a positive frequency offset estimation indicates that the frequency is too large, and a negative value indicates that the frequency is too small. Then the system physical subframe number corresponding to the physical subframe is set to 0, the UTC time is adjusted to 0:00 on January 1, 2024, the start time of the subframe is advanced by 200+10=210us, and the frequency is reduced by 600+50=650Hz. After the adjustment is completed, the terminal device completes synchronization.

[0062] For another example, if a physical subframe passes the SLSS reception detection, the synchronization information such as the subframe number (assuming it is 0) carried by the PSBCH on the physical subframe that passes the detection is obtained, and the timing estimate and frequency offset estimate obtained by the current measurement are obtained. Assuming that the timing estimate is 200us and the frequency offset estimate is 600Hz, it can be negotiated that a positive value of the timing estimate indicates a timing delay, a negative value indicates a timing advance, a positive value of the frequency offset estimate indicates that the frequency is too large, and a negative value indicates that the frequency is too small, then the system physical subframe number corresponding to this subframe is set to 0, the start time of the subframe is advanced by 200us, and the frequency is reduced by 600Hz. After the adjustment is completed, the terminal device completes the synchronization.

[0063] The joint synchronization method for V2X provided in the embodiment of the present application, by using two kinds of synchronization information for joint synchronization, can detect the synchronization signal more quickly, thereby reducing the time required for synchronization, can improve the accuracy of synchronization, and can adapt to various channel environments to ensure successful detection of synchronization signals at different code rates, thereby improving synchronization efficiency.

[0064] In some embodiments, performing beacon signal reception detection on each physical subframe includes: Determine whether a physical side link control channel PSCCH signal carried by the physical subframe meets the beacon synchronization signal characteristics, and perform physical side link shared channel PSSCH decoding check on the data carried by the physical subframe; If the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding verification is successful, determine that the beacon signal reception detection is passed; and / or When the PSCCH signal does not conform to the beacon synchronization signal characteristics, or the PSSCH decoding check fails, it is determined that the beacon signal reception detection fails.

[0065] Specifically, the beacon signal reception detection mainly includes PSCCH signal detection and PSSCH decoding verification. Among them, PSCCH signal detection is to determine whether the PSCCH signal meets the beacon synchronization signal characteristics. PSSCH decoding verification is to determine whether the PSSCH decoding can pass the cyclic redundancy check (CRC).

[0066] When performing beacon signal reception detection, determine whether the PSCCH signal carried by the currently detected physical subframe meets the beacon synchronization signal characteristics, and determine whether the PSSCH decoding passes the CRC check. If the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding check succeeds, it indicates that the beacon signal reception detection passes; if the PSCCH signal does not meet the beacon synchronization signal characteristics, or the PSSCH decoding check fails, it indicates that the beacon signal reception detection fails.

[0067] The joint synchronization method for V2X provided in the embodiment of the present application accurately detects the beacon synchronization signal by judging whether the PSCCH signal meets the beacon synchronization signal characteristics and whether the PSSCH decoding check is passed, thereby ensuring the effectiveness of the synchronization signal detection.

[0068] In some embodiments, performing SLSS reception detection on each physical subframe includes: Determine whether the physical subframe is a reserved subframe for sending SLSS, and perform physical layer side link broadcast channel PSBCH decoding check on the data carried by the physical subframe; In a case where the physical subframe is a reserved subframe for sending SLSS and the PSBCH decoding check succeeds, determining that the SLSS reception detection passes; and / or When the physical subframe is not a reserved subframe for sending SLSS, or the PSBCH decoding check fails, it is determined that the SLSS reception detection fails.

[0069] Specifically, SLSS reception detection mainly includes SLSS subframe judgment and PSBCH decoding verification. Among them, SLSS subframe judgment is to judge whether the physical subframe is a reserved subframe for sending SLSS. PSBCH decoding verification is to judge whether PSBCH decoding can pass CRC verification.

[0070] When performing beacon signal reception detection, determine whether the currently detected physical subframe is a reserved subframe for sending SLSS, and determine whether the PSBCH decoding can pass the CRC check. If the physical subframe is a reserved subframe for sending SLSS and the PSBCH decoding check succeeds, it means that the SLSS reception detection passes; if the physical subframe is not a reserved subframe for sending SLSS, or the PSBCH decoding check fails, it means that the SLSS reception detection fails.

[0071] In some embodiments, the determining whether the physical subframe is a reserved subframe for sending the SLSS includes: Low-pass filtering and down-sampling are performed on the data carried by the physical subframe to obtain two columns of side link primary synchronization signal PSSS symbols, two columns of side link secondary synchronization signal SSSS symbols, and three columns of physical layer side link broadcast channel PSBCH demodulation reference signal DMRS symbols; Perform correlation detection according to the PSSS symbol, the SSSS symbol and the PSBCH DMRS symbol to obtain a correlation value; When the correlation value is greater than a preset threshold, determining that the physical subframe is a reserved subframe for sending the SLSS; and / or When the correlation value is less than or equal to the preset threshold, it is determined that the physical subframe is not a reserved subframe for sending the SLSS.

[0072] Specifically, SLSS subframe judgment can be achieved through correlation detection. First, the data carried by the physical subframe is low-pass filtered and down-sampled to obtain two columns of PSSS symbols, two columns of SSSS symbols, and three columns of PSBCH DMRS symbols. Then, correlation detection is performed based on these symbols to determine whether the correlation value obtained by the detection is greater than the preset threshold. If the correlation value is greater than the preset threshold, the physical subframe is considered to be a reserved subframe for sending SLSS, and the start time of a subframe is obtained. At the same time, the data carried by the physical subframe is subjected to PSBCH decoding verification; if the correlation value is less than or equal to the preset threshold, the physical subframe is considered not to be a reserved subframe for sending SLSS.

[0073] The joint synchronization method for V2X provided in the embodiment of the present application determines the reserved subframe for sending SLSS through correlation detection and preset threshold, and jointly detects SLSS in combination with PSSCH decoding verification, thereby ensuring the accuracy and effectiveness of synchronization signal detection.

[0074] In some embodiments, the performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Before the first timer expires, performing beacon signal reception detection on each physical subframe; and / or Before the second timer expires, SLSS reception detection is performed on each physical subframe.

[0075] Specifically, one way to perform synchronization signal reception detection is to alternately detect the beacon synchronization signal and the SLSS.

[0076] In the embodiment of the present application, two timers are used to realize the alternation of beacon signal reception detection and SLSS reception detection. The activation of the first timer and the activation of the second timer are mutually exclusive. When the first timer is activated, the second timer is disabled, and when the second timer is activated, the first timer is disabled. After the first timer is activated and before it ends, the beacon signal reception detection is performed on the physical subframe; after the second timer is activated and before it ends, the SLSS reception detection is performed on the physical subframe.

[0077] For example, after the terminal device is turned on or when searching for the synchronization signal again, the first timer is started, and a beacon signal reception detection is performed on each physical subframe before the first timer expires. After the first timer expires, the second timer is started, and an SLSS reception detection is performed on each physical subframe before the second timer expires.

[0078] For another example, after the terminal device is turned on or searches for the synchronization signal again, the second timer is started, and an SLSS reception detection is performed on each physical subframe before the second timer expires. After the second timer expires, the first timer is started, and a beacon signal reception detection is performed on each physical subframe before the first timer expires.

[0079] The joint synchronization method for V2X provided in the embodiment of the present application uses two timers to realize alternating detection of two synchronization signals, so that the terminal device can quickly detect the synchronization signal for synchronization, and can be flexibly applied to a variety of scenarios and adapted to the sending terminal devices of different synchronization signal sending schemes, thereby improving the synchronization success rate.

[0080] In some embodiments, the method further comprises: When the terminal device is turned on or starts searching for a synchronization signal, starting the first timer; When the first timer times out and no physical subframe is detected by beacon signal reception, start the second timer; and / or When the second timer times out and no physical subframe passes SLSS reception detection, the first timer is started.

[0081] Specifically, the triggering condition for starting the first timer includes that the terminal device is turned on or starts searching for synchronization signals, and the second timer times out, and no physical subframe passes the SLSS reception detection within the second timer. The triggering condition for starting the second timer is that the first timer times out, and no physical subframe passes the beacon signal reception detection within the second timer.

[0082] For example, after the terminal device is turned on or when it searches for the synchronization signal again, the first timer is started, and a beacon signal reception detection is performed before the first timer ends. If no physical subframe passes the beacon signal reception detection until the first timer times out, the second timer is started, and an SLSS reception detection is performed before the second timer ends. If no physical subframe passes the SLSS reception detection until the second timer times out, the first timer is started, and the beacon signal reception detection is continued. The beacon signal reception detection and the SLSS reception detection are repeated until the detection of a physical subframe passes, and the timer is stopped.

[0083] In some embodiments, the method further comprises: In the case where there is a physical subframe detected by receiving a beacon signal, ending the first timer; When the first timer times out, end the first timer; In the case that there is a physical subframe detected by SLSS reception, ending the second timer; and / or When the second timer times out, the second timer is ended.

[0084] Specifically, the triggering conditions for the end of the first timer include: there is a physical subframe detected by beacon signal reception before the first timer times out, and the first timer times out.

[0085] The triggering conditions for the second timer to end include: a physical subframe is detected by SLSS reception before the second timer times out, and the second timer times out.

[0086] For example, Figure 2 This is a second flow chart of the joint synchronization method for V2X provided by the present invention, such as Figure 2 As shown, the specific steps of alternately detecting the beacon synchronization signal and SLSS for synchronization are as follows: Step 1: After the terminal device is turned on or searches for the synchronization signal again, two synchronization signals are captured and a first timer is started. The first timer can be 201 milliseconds, corresponding to 201 physical subframes.

[0087] Step 2: The physical layer searches for the rising edge and falling edge of the power value of the radio frequency data in the sliding window. If the rising edge and falling edge that match the length of a transmission subframe are found, the starting position for synchronization signal reception detection is determined, and the process goes to step 3. If the starting position is not found after the first timer times out, that is, after the timing exceeds 201 milliseconds, the process goes to step 4.

[0088] Step 3: Starting from the starting position, the physical layer performs PSCCH detection and PSSCH detection decoding on the data of each physical subframe. If the PSCCH meets the beacon synchronization signal characteristics and the PSSCH decoding verification is successful, go to step 7; if the PSCCH does not meet the synchronization signal characteristics or the PSSCH decoding verification fails and the first timer has not timed out, continue to perform PSCCH detection and PSSCH decoding verification on the next physical subframe; if no physical subframe passes the PSCCH detection and PSSCH decoding verification until the first timer times out, go to step 4.

[0089] Step 4: Start the second timer. The second timer may be 256 milliseconds, corresponding to 256 physical subframes.

[0090] Step 5: The physical layer performs low-pass filtering and down-sampling on the RF data in the sliding window to obtain two columns of PSSS symbols, two columns of SSSS symbols, and three columns of PSBCH DMRS symbols and performs correlation detection, and then determines whether the correlation value is greater than the threshold. If the correlation value is greater than the threshold, go to step 6; if the correlation value is less than the threshold, execute step 5 again.

[0091] Step 6. If the correlation value is greater than the threshold, it is determined that the currently detected physical subframe is a reserved subframe for sending SLSS, and PSBCH detection and decoding are performed on the data carried by the physical subframe. If the PSBCH decoding check is successful, go to step 7; if the PSBCH decoding check fails and the second timer has not timed out, go to step 5; if no physical subframe passes the PSBCH decoding check until the second timer times out, go to step 1.

[0092] Step 7: Report the synchronization information to the upper layer so as to make synchronization adjustments.

[0093] The joint synchronization method for V2X provided in the embodiment of the present application improves the speed of detecting the synchronization signal by alternately detecting the two synchronization signals, SLSS and beacon synchronization signal. It can adapt to various channel environments to ensure the successful detection of synchronization signals at different code rates and can adapt to roadside equipment with different synchronization signal sending schemes, thereby improving the success rate of synchronization and improving the synchronization efficiency.

[0094] The joint synchronization method for V2X provided in the above embodiments is further described below through specific examples: Assume that sending device A sends a beacon synchronization signal with an offset of 0 logical subframes and a period of 100 logical subframes, and sends an SLSS synchronization signal in a reserved subframe, that is, SLSS synchronization signals are sent at physical subframes 0, 256, 512, etc., and beacon synchronization signals are sent at physical subframes 1, 101, 201, 302, 402, 502, 603 (corresponding to logical subframes 0, 100, 200, 300, 400, 500, 600, respectively), and receiving device B is synchronized according to the synchronization signal.

[0095] Example 1: Figure 3 FIG. 1 is one of the frame structure diagrams of the synchronization signal search example provided by the present invention, such as Figure 3 As shown, when the receiving device B searches for the synchronization signal, it starts to search for the synchronization signal alternately from the position of physical subframe 0 (first detect the beacon signal 201 milliseconds, and then detect the SLSS 256 milliseconds). Then, the rising edge and the falling edge are found at the position of physical subframe 0, thereby determining that the starting position is the position of physical subframe 1. Then, the beacon signal reception detection is performed on each physical subframe starting from physical subframe 1. At the position of physical subframe 1, the PSCCH signal meets the beacon signal characteristics and the PSSCH CRC check is successful. It is considered that the beacon signal reception detection is successful at this time, and synchronization is entered.

[0096] Example 2: Figure 4 FIG. 2 is a second schematic diagram of a frame structure of a synchronization signal search example provided by the present invention. Figure 4 As shown, when the receiving device B searches for the synchronization signal, it starts to search for the synchronization signal alternately from the position of the physical subframe 102 (first detect the beacon signal 201 milliseconds, and then detect the SLSS signal 256 milliseconds). Then, the rising edge and the falling edge are found at the position of the physical subframe 201, and the starting position is determined to be the position of the physical subframe 202. Then, starting from the physical subframe 202, the beacon signal reception detection is performed on each subframe. At the position of the physical subframe 302, the PSCCH signal meets the beacon signal characteristics and the PSSCH CRC check is successful. It is considered that the beacon signal reception detection is successful at this time, and synchronization is entered.

[0097] Example 3: Figure 5 FIG. 3 is a schematic diagram of a frame structure of a synchronization signal search example provided by the present invention. Figure 5As shown, when the receiving device B searches for the synchronization signal, it starts to search for the synchronization signal alternately from the position of physical subframe 0 (first detect the beacon signal 201 milliseconds, and then detect the SLSS 256 milliseconds). Then, the rising edge and the falling edge are found at the position of physical subframe 0, and the starting position is determined to be the position of physical subframe 1. Then, beacon signal reception detection is performed on each physical subframe starting from physical subframe 1. The detection fails at the positions of physical subframes 1 and 101 due to the poor channel environment, and the process switches to the SLSS reception detection process. The SLSS reception detection succeeds at the position of physical subframe 256, and synchronization is entered.

[0098] In some embodiments, the performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Beacon signal reception detection and SLSS reception detection are performed on each physical subframe.

[0099] Specifically, one way to perform synchronization signal reception detection is to detect the beacon synchronization signal and the SLSS simultaneously, that is, to perform beacon signal reception detection and SLSS reception detection on each physical subframe.

[0100] For example, Figure 6 This is a flowchart of the joint synchronization method for V2X provided by the present invention, as shown in FIG. Figure 6 As shown, the specific steps of simultaneously detecting the beacon synchronization signal and SLSS for synchronization are as follows: Step 1: After the terminal device is turned on or when searching for the synchronization signal again, the rising edge and falling edge of the power value of the RF data are searched. If the rising edge and falling edge that match the length of a transmitted subframe are found, the starting position for the synchronization signal reception detection is determined, and the process goes to step 2. If the rising edge and falling edge found do not match the length of a transmitted subframe, the rising edge and falling edge of the power value of the RF data are continued to be searched.

[0101] Step 2: Starting from the starting position, perform beacon signal reception detection (including PSCCH detection and PSSCH detection decoding) on ​​each physical subframe. If PSCCH meets the beacon synchronization signal characteristics and PSSCH decoding verification succeeds, go to step 4; if PSCCH does not meet the beacon synchronization signal characteristics or PSSCH decoding verification fails, go to step 3.

[0102] Step 3: Perform SLSS reception detection on the physical subframe, that is, after low-pass filtering and down-sampling the RF data, perform PSBCH detection and decoding on the data carried by the physical subframe. If the PSBCH decoding test succeeds, go to step 4; if the PSBCH decoding test fails, go to step 2 and perform beacon signal reception detection on the next physical subframe.

[0103] Step 4: Report the synchronization information to the upper layer for synchronization adjustment.

[0104] The joint synchronization method for V2X provided in the above embodiment is further described below through a specific example: Example 4: Figure 7 FIG. 4 is a schematic diagram of a frame structure of a synchronization signal search example provided by the present invention. Figure 7 As shown, when the receiving device B searches for the synchronization signal, it starts to search for the synchronization signal simultaneously from the position of physical subframe 0, then finds the rising edge and the falling edge at the position of physical subframe 0, determines that the starting position is the position of physical subframe 1, and then starts from physical subframe 1 to simultaneously perform reception detection of the beacon synchronization signal and the SLSS signal for each physical subframe. At the position of physical subframe 1, the PSCCH signal meets the characteristics of the beacon synchronization signal and the PSSCH CRC check is successful, and it is considered that the beacon signal reception detection is successful at this time, and synchronization is entered.

[0105] Example 5: Figure 8 FIG. 5 is a schematic diagram of a frame structure of a synchronization signal search example provided by the present invention. Figure 8 As shown, when the receiving device B searches for the synchronization signal, it starts to search for the synchronization signal simultaneously from the position of physical subframe 102, then finds the rising edge and the falling edge at the position of physical subframe 201, determines the starting position as the position of physical subframe 202, and then starts from physical subframe 202 to simultaneously perform reception detection of the beacon synchronization signal and the SLSS signal for each subframe, and succeeds in the PSBCH CRC check of the SLSS signal at the position of physical subframe 256, and it is considered that the SLSS reception detection is successful at this time, and synchronization is entered.

[0106] The joint synchronization method for V2X provided in the embodiment of the present application improves the efficiency and success rate of detecting the synchronization signal by simultaneously detecting the beacon synchronization signal and the SLSS, and can use the measurement values ​​detected by the two synchronization signals to further improve the accuracy of synchronization. It can use roadside equipment that can adapt to various channel environments to ensure successful detection of synchronization signals at different code rates and can adapt to different synchronization signal sending schemes, thereby improving the synchronization success rate and synchronization efficiency.

[0107] In some embodiments, determining the position of the first transmitted subframe includes: Detect the rising edge and falling edge of the power value of the radio frequency data; In the case where the interval time between a group of rising edges and falling edges is the length of a transmission subframe, the time domain position corresponding to the group of rising edges and falling edges is determined as the position of the first transmission subframe.

[0108] Specifically, the position of the first transmission subframe can be determined based on the length of the transmission subframe. When the terminal device is turned on or starts searching for the synchronization signal again, the physical layer determines the power value of the RF data. When it is determined that the interval between the rising edge and the falling edge of a certain set of power values ​​is the length of a transmission subframe, the time domain position corresponding to the rising edge and the falling edge is a transmission subframe, thereby obtaining the position of the first transmission subframe.

[0109] For example, a sliding window is set, the length of which is the length of a transmitting subframe, and the starting position of the sliding window is the time domain position when the power is turned on or the synchronization signal is re-searched. During the sliding process, it is determined whether a rising edge of the RF data power value and a falling edge immediately following the rising edge (i.e., a set of rising edges and falling edges) appear in the sliding window, and the interval time between the rising edge and the falling edge is equal to the length of the sliding window. If the sliding window slides to a certain position and a set of rising edges and falling edges that meet the above conditions appear in it, then the time domain position corresponding to the sliding window at this time is the position of the first transmitting subframe.

[0110] The joint synchronization method for V2X provided in the embodiment of the present application judges the power value of the radio frequency data. When the interval time between the rising edge and the falling edge meets the length of a transmitted subframe, the interval time is used as the position of the first transmitted subframe, thereby determining the position of each subsequent physical subframe and ensuring the smooth reception and detection of the synchronization signal.

[0111] In some embodiments, when synchronization is completed, the method further includes: Determine whether a synchronization signal is received in the current physical subframe; When the current physical subframe receives a synchronization signal, the value of the first counter is cleared, and synchronization maintenance is performed based on the synchronization information carried by the synchronization signal.

[0112] Specifically, after synchronization is completed, synchronization maintenance is also performed: beacon synchronization signals and SLSS are continuously received and detected. After receiving the synchronization signal, synchronization maintenance is performed based on the synchronization information carried by the synchronization signal. The synchronization information includes synchronization level, subframe number, etc.

[0113] After entering the synchronization state, it is determined whether the synchronization signal is received in the current physical subframe. If the synchronization signal is received, the value of the first counter is cleared, and synchronization maintenance is performed according to the synchronization information carried by the synchronization signal. The first counter is used to record the number of failures of synchronization signal reception detection (including beacon signal reception detection and SLSS reception detection), that is, the number of times the synchronization signal is not received in the physical subframe.

[0114] In the joint synchronization method for V2X provided in the embodiment of the present application, the terminal device continues to receive synchronization signals and perform synchronization maintenance after completing synchronization, thereby ensuring real-time synchronization adjustment of the terminal device, guaranteeing synchronization accuracy, and improving synchronization stability.

[0115] In some embodiments, the method further comprises: Determine whether the current physical subframe is a reserved subframe; If the current physical subframe is not a reserved subframe, performing a beacon signal reception detection on the current physical subframe, and if the beacon signal reception detection passes, determining that a beacon synchronization signal is received in the current physical subframe; and / or In the case that the current physical subframe is a reserved subframe, an SLSS reception detection is performed on the current physical subframe, and in the case that the SLSS reception detection passes, it is determined that the SLSS is received in the current physical subframe.

[0116] Specifically, the synchronization maintenance first needs to determine whether a synchronization signal is received. Specifically, it can be divided into two cases according to whether the current physical subframe is a reserved subframe, and further determine whether the synchronization signal is received.

[0117] If the current physical subframe is not a reserved subframe, a beacon signal reception detection (including PSCCH signal detection and PSSCH decoding check, etc.) is performed on the physical subframe. If the beacon signal reception detection fails, the next physical subframe is judged. If the beacon signal reception detection passes, it indicates that the beacon synchronization signal is received in the physical subframe.

[0118] If the current physical subframe is a reserved subframe, SLSS reception detection (including PSBCH decoding check, etc.) is performed on the physical subframe. If the SLSS reception detection fails, the next physical subframe is judged. If the SLSS reception detection passes, it indicates that SLSS is received in the reserved subframe.

[0119] The joint synchronization method for V2X provided in the embodiment of the present application performs synchronization signal detection according to different situations by judging whether the physical subframe is a reserved subframe. The operation is simple, unnecessary detection operations are reduced, and the efficiency of synchronization maintenance is ensured.

[0120] In some embodiments, the method further comprises: In the case that the current physical subframe does not receive a synchronization signal, adding one to the value of the first counter, and determining whether the value of the first counter exceeds a first threshold value; When the value of the first counter exceeds the first threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the first counter does not exceed the first threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

[0121] Specifically, after entering the synchronization state, it is determined whether a synchronization signal is received within a period of time. If no synchronization signal is received within a period of time, resynchronization is required, that is, determining the position of the first transmitted subframe, performing beacon signal reception detection and / or SLSS reception detection and synchronization operations.

[0122] The first counter can be used to represent the duration of synchronization maintenance, and to determine whether a synchronization signal is received in the current physical subframe. If the synchronization signal is not received, the value of the first counter is increased by one, and it is determined whether the value of the first counter exceeds the first threshold value. If the value of the first counter exceeds the first threshold value, the synchronization operation is performed again, that is, the position of the first transmitted subframe is re-determined and the synchronization operation is performed. If the value of the first counter does not exceed the first threshold value, it is continued to determine whether the synchronization signal is received in the next physical subframe.

[0123] For example, the terminal device detects the beacon synchronization signal at the position of physical subframe 1 and completes the synchronization. After synchronization, it continues to detect the synchronization signal of physical subframe 2. The first threshold value is set to 50000. At this time, the value of the first counter is 0. If no synchronization signal is detected in physical subframe 2, the value of the first counter is increased by one. At this time, the value of the counter is 1, which does not exceed the first threshold value of 50000. It continues to judge whether the synchronization signal is detected in physical subframe 3. Until the synchronization signal is detected in physical subframe 100, the value of the first counter is cleared from 98 to zero, and synchronization maintenance is performed according to the current measurement results and the synchronization information carried by the synchronization signal, and the physical subframe 101 is continued to be judged.

[0124] The joint synchronization method for V2X provided in the embodiment of the present application controls the duration of synchronization maintenance by setting a first counter. If no synchronization signal is received during this period of time, it indicates that a synchronization abnormality may have occurred and re-synchronization is required. If a synchronization signal is received, the synchronization is adjusted in real time according to the synchronization signal, thereby improving the accuracy and effectiveness of the synchronization.

[0125] In some embodiments, when the synchronization signal is a beacon synchronization signal, performing synchronization maintenance based on synchronization information carried by the synchronization signal includes: Determining whether the synchronization level in the synchronization information carried by the beacon synchronization signal is higher than or equal to the current system synchronization level; When the synchronization level in the synchronization information is higher than or equal to the current system synchronization level, updating the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and synchronizing according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result; and / or In a case where the synchronization level of the beacon synchronization signal is lower than the current system synchronization level, it is determined whether a synchronization signal is received in a next physical subframe.

[0126] Specifically, when a synchronization signal is received and is a beacon synchronization signal, synchronization maintenance may be performed based on the synchronization level in the synchronization information carried by the beacon synchronization signal.

[0127] Compare the synchronization level of the beacon synchronization signal with the current system synchronization level: if the synchronization level of the beacon synchronization signal is higher than or equal to the current system synchronization level, update the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, obtain a second synchronization measurement result, and synchronize according to the synchronization information carried by the beacon synchronization signal and the second synchronization measurement result; if the synchronization level of the beacon synchronization signal is lower than the current system synchronization level, continue to determine whether the next physical subframe receives the synchronization signal.

[0128] For example, after synchronization is completed, the physical layer performs PSCCH detection and PSSCH decoding verification on a certain physical subframe. If the PSCCH signal meets the characteristics of the beacon synchronization signal and the PSSCH decoding passes the CRC check, it indicates that the beacon signal reception detection is passed and the beacon synchronization signal is received in the physical subframe. The synchronization information (including subframe number, UTC time, timing estimation residual, frequency offset estimation residual, and synchronization level, etc.) carried by the beacon synchronization signal and the synchronization measurement results are reported to the upper layer, and the upper layer determines whether the synchronization level in the synchronization information carried by the beacon synchronization signal is higher than or equal to the current system synchronization level. If the synchronization level in the synchronization information is equal to or higher than the local system synchronization level, synchronization adjustment needs to be performed based on the synchronization information and the updated synchronization measurement results. If the synchronization level in the synchronization information is lower than the current system synchronization level, no synchronization adjustment is required, and the next physical subframe continues to be determined whether the synchronization signal is received.

[0129] The joint synchronization method for V2X provided in the embodiment of the present application, after completing the synchronization, if a beacon synchronization signal is received, the synchronization level in the synchronization information carried by the beacon synchronization signal can be compared with the current system synchronization level to determine whether synchronization adjustment is required, thereby realizing synchronization maintenance after synchronization and improving and strengthening the synchronization strategy.

[0130] In some embodiments, updating the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and performing synchronization according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result, includes: updating a timing estimate according to a timing estimate residual carried by the beacon synchronization signal and a timing estimate in the second synchronization measurement result, and updating a frequency offset estimate according to a frequency offset estimate residual carried by the beacon synchronization signal and a frequency offset estimate in the synchronization measurement result; Synchronization is performed based on the updated timing estimate, the updated frequency offset estimate, and the synchronization information carried by the beacon synchronization signal.

[0131] Specifically, determine the timing estimation residual and the frequency offset estimation residual in the synchronization information carried by the beacon synchronization signal, and determine the timing estimation and the frequency offset estimation in the second synchronization measurement result, update the timing estimation based on the timing estimation residual and the timing estimation, and update the frequency offset estimation based on the frequency offset estimation residual and the frequency offset estimation, synchronize according to the updated timing estimation and frequency offset estimation and the synchronization information carried by the beacon synchronization signal, that is, adjust the starting position of the subframe according to the updated timing estimation, and adjust the crystal oscillator according to the updated frequency offset estimation to obtain a more accurate frequency offset estimate.

[0132] The joint synchronization method for V2X provided in the embodiment of the present application obtains a more accurate timing estimate by jointly calculating the timing estimate residual and the reported timing estimate, and obtains a more accurate frequency offset estimate by jointly calculating the frequency offset estimate residual and the reported frequency offset estimate, thereby realizing real-time and accurate synchronization dimension adjustment.

[0133] In some embodiments, when the synchronization level of the beacon synchronization signal is higher than or equal to the current system synchronization level, the method further includes: Determining whether the subframe number in the synchronization information is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

[0134] Specifically, after receiving the beacon synchronization signal and performing synchronization adjustment according to the synchronization information carried by the beacon synchronization signal, further synchronization maintenance is performed based on the subframe number in the synchronization information: determine whether the subframe number in the synchronization information is equal to the system subframe number. If they are equal, clear the value of the second counter and continue to determine whether the synchronization signal is received in the next physical subframe.

[0135] In some embodiments, the method further comprises: When the subframe number in the synchronization information is not equal to the system subframe number, adding one to the value of the second counter, and determining whether the value of the second counter exceeds a second threshold value; When the value of the second counter exceeds the second threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the second counter does not exceed the second threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

[0136] Specifically, after synchronization adjustment is performed according to the synchronization information carried by the beacon synchronization signal, if the subframe number in the synchronization information is not equal to the system subframe number, the value of the second counter is increased by one, and the value of the second counter is the number of times the subframe number in the synchronization information is not equal to the system subframe number (or the UTC time in the synchronization information is not equal to the system UTC time). It is determined whether the value of the second counter exceeds the second threshold value: if it exceeds, it is necessary to resynchronize, that is, re-determine the position of the first transmitted subframe and perform the synchronization operation; if the value of the second counter does not exceed the second threshold value, it is continued to determine whether the synchronization signal is received in the next physical subframe.

[0137] The joint synchronization method for V2X provided in the embodiment of the present application, after using the synchronization information of the beacon synchronization signal for synchronization adjustment, determines whether the subframe number in the synchronization information is continuously not equal to the system subframe number for more than a preset time length (corresponding to the second threshold value). If so, it indicates that the synchronization may be abnormal and the synchronization process needs to be re-executed, thereby ensuring the accuracy and effectiveness of the synchronization.

[0138] In some embodiments, when the synchronization signal is SLSS, the method further includes: Determine whether the subframe number in the synchronization information carried by the SLSS is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

[0139] Specifically, when a synchronization signal is received and is a SLSS, synchronization maintenance may be performed based on the subframe number in the synchronization information carried by the SLSS.

[0140] It is determined whether the subframe number in the synchronization information is equal to the system subframe number. If they are equal, the value of the second counter is cleared, and it is continued to be determined whether the synchronization signal is received in the next physical subframe.

[0141] In some embodiments, the method further comprises: When the subframe number in the synchronization information is not equal to the system subframe number, adding one to the value of the second counter, and determining whether the value of the second counter exceeds a second threshold value; When the value of the second counter exceeds the second threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the second counter does not exceed the second threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

[0142] Specifically, if the subframe number in the synchronization information carried by SLSS is not equal to the system subframe number, the value of the second counter is increased by one to determine whether the value of the second counter exceeds the second threshold value: if it exceeds, resynchronization is required, that is, the position of the first transmitted subframe is re-determined and the synchronization operation is performed; if the value of the second counter does not exceed the second threshold value, it is continued to determine whether the synchronization signal is received in the next physical subframe.

[0143] The joint synchronization method for V2X provided in the embodiment of the present application uses the subframe number in the synchronization information carried by SLSS for synchronization maintenance. When the subframe number in the synchronization information is not equal to the system subframe number for more than a preset period of time (corresponding to the second threshold value), it indicates that the synchronization may be abnormal and the synchronization process needs to be re-executed, thereby ensuring the accuracy and effectiveness of the synchronization.

[0144] Fig. 9 This is a fourth flow chart of the joint synchronization method for V2X provided by the present invention, such as Fig. 9 As shown in the figure, after entering the synchronization state, the steps for synchronization maintenance are as follows: Step 1: Determine whether the next physical subframe is a reserved subframe. If it is a reserved subframe, go to step 2; if it is not a reserved subframe, go to step 4.

[0145] Step 2: The next physical subframe is a reserved subframe. The physical layer performs PSBCH detection in the reserved subframe. If the PSBCH decoding is successful, indicating that the SLSS is received in the reserved subframe, the count d is cleared, and the synchronization information and synchronization measurement results are reported to the upper layer. The upper layer makes synchronization adjustments based on the measurement information and goes to step 3. If the PSBCH decoding fails, the count d is increased by 1, and it is determined whether the count d exceeds 50000. If it exceeds, go to step 7. If it does not exceed, go to step 1.

[0146] Step 3: Determine whether the subframe number parsed from the synchronization information of SLSS is equal to the system subframe number. If they are equal, clear the count c1 and go to step 1. If they are not equal, add 1 to the count c1 and determine whether the count c1 exceeds 10. If so, go to step 7; if not, go to step 1.

[0147] Step 4: The next physical subframe is not a reserved subframe, and the physical layer performs PSCCH and PSSCH detection in the non-reserved subframe. If the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding is successful, indicating that the beacon synchronization signal is received in the non-reserved subframe, the count d is cleared and the process goes to step 5; if the PSCCH signal does not meet the beacon synchronization signal characteristics or the PSSCH decoding fails, the count d is increased by 1, and it is determined whether the count d exceeds 50000. If so, go to step 7; if not, go to step 1.

[0148] Step 5: parse the synchronization level from the synchronization information of the beacon synchronization signal, and determine whether the synchronization level is higher than or equal to the system synchronization level. If the synchronization level is higher than or equal to the system synchronization level, report the synchronization information and synchronization measurement results to the upper layer, and the upper layer makes synchronization adjustments based on the measurement information, and go to step 6; if the synchronization level is lower than the system synchronization level, go to step 1.

[0149] Step 6: Determine whether the subframe number is equal to the system subframe number from the subframe number parsed from the synchronization information of the beacon synchronization signal. If they are equal, clear the count c2 and go to step 1. If they are not equal, add 1 to the count c2 and determine whether the count c2 exceeds 10. If so, go to step 7; if not, go to step 1.

[0150] Step 7: Re-search for synchronization signals and execute the synchronization process.

[0151] The joint synchronization method for V2X provided in the above embodiment is further described below through a specific example: The sending device A sends a beacon synchronization signal with an offset of 0 logical subframes and a period of 100 logical subframes, and sends an SLSS synchronization signal in the reserved subframe, that is, it sends SLSS synchronization signals at physical subframes 0, 256, 512, etc., and sends beacon synchronization signals at physical subframes 1, 101, 201, 302, 402, 502, 603 (corresponding to logical subframes 0, 100, 200, 300, 400, 500, 600, respectively). The receiving device B has completed synchronization by receiving the beacon signal or SLSS signal, and then performs synchronization maintenance.

[0152] Example 6: Receive SLSS synchronization signals at physical subframes 0, 256, 512, etc. When the PSBCH CRC check succeeds, determine whether the subframe number carried by the PSBCH is equal to the physical subframe number of the current system, and make adjustments based on the timing estimate and frequency offset estimate obtained from physical layer measurements. If the subframe numbers are not equal for 10 consecutive times, resynchronize; otherwise, continue to determine the next physical subframe and perform synchronization maintenance.

[0153] Example 7: Beacon synchronization signals are received at physical subframes 1, 101, 201, 302, 402, 502, 603, etc. When the PSCCH signal meets the characteristics of the beacon synchronization signal and the PSSCH CRC check is successful, determine whether the current system synchronization level is higher than or equal to the synchronization level carried by the beacon signal. If so, make adjustments based on the timing estimate and frequency offset estimate obtained from physical layer measurements and the timing estimate residual and frequency offset estimate residual carried by the beacon signal. At the same time, determine whether the subframe number and UTC time are equal to the locally stored subframe number and UTC time. If the subframe number or UTC time are not equal for 10 consecutive times, resynchronize.

[0154] In some embodiments, the specific steps of performing synchronization include one or more of the following: Adjust the subframe number of the current system according to the subframe number in the synchronization information; adjusting the starting position of the subframe according to the timing estimate in the synchronization measurement result; Adjust the crystal oscillator based on the frequency offset estimate from the synchronous measurement results; Adjust the UTC of the current system according to the coordinated universal time UTC in the synchronization information; Determine the synchronization level of the current system according to the synchronization level in the synchronization information; Calculating a target timing estimate based on the timing estimate residual in the synchronization information and the timing estimate in the synchronization measurement result, and adjusting the starting position of the subframe based on the target timing estimate; Calculating a target frequency offset estimate based on the frequency offset estimate residual in the synchronization information and the frequency offset estimate in the synchronization measurement result, and adjusting the crystal oscillator based on the target frequency offset estimate; and / or Leap seconds are adjusted according to the leap second indication in the sync information.

[0155] Specifically, when performing synchronization or synchronization maintenance, the upper layer of the terminal device adjusts the system physical subframe number according to the subframe number in the synchronization information reported by the physical layer, adjusts the starting position of the subframe according to the timing estimate in the reported synchronization measurement result, and adjusts the crystal oscillator according to the frequency deviation estimate in the reported synchronization measurement result.

[0156] If the detected synchronization signal is a beacon synchronization signal, more adjustments can be made, including adjusting the current system UTC according to the UTC time, setting the current system synchronization level according to the synchronization level, and adjusting the start position of the subframe by jointly calculating a more accurate timing estimate based on the timing estimation residual and the reported timing estimation measurement result, and adjusting the crystal oscillator by jointly calculating a more accurate frequency offset estimate based on the frequency offset estimation residual and the reported frequency offset estimation measurement result, and adjusting the leap second according to the leap second indication. At this time, the timing adjustment amount and the frequency offset adjustment amount are respectively: Timing adjustment = timing estimate + timing residual Frequency offset adjustment = frequency offset estimation + frequency offset residual Among them, the timing estimation and frequency offset estimation are the measurement values ​​obtained from this physical layer measurement, the timing residual and frequency offset residual are the timing and frequency offset errors between the signal source carried in the beacon signal and the GNSS, and the timing adjustment and frequency offset adjustment are the timing and frequency offset sizes that need to be adjusted this time.

[0157] The above-mentioned synchronous measurement result includes a first synchronous measurement result and a second synchronous measurement result.

[0158] The joint synchronization method for V2X provided in the embodiment of the present application can perform synchronization and synchronization adjustment through the above-mentioned multiple operations before and after synchronization, realizes real-time synchronization and adjustment of terminal equipment, ensures synchronization accuracy, and improves synchronization stability. Compared with synchronization using only beacon synchronization signals or only SLSS signals, the joint synchronization method for V2X provided in the embodiment of the present application uses two synchronization signals for synchronization at the same time, which can detect the synchronization signal as early as possible, thereby reducing the time required for synchronization, and uses the measurement values ​​detected by the two synchronization signals to improve the synchronization accuracy, and can also adapt to various channel environments to ensure the successful detection of synchronization signals at different code rates, thereby improving synchronization efficiency, and adapt to roadside equipment with different synchronization signal sending schemes to improve the synchronization success rate.

[0159] Fig.10 is a schematic diagram of the structure of a joint synchronization device for V2X provided by the present invention, such as Fig.10 As shown, the present invention provides a joint synchronization device for V2X, including a first determination module 1001, a synchronization signal reception detection module 1002 and a synchronization module 1003.

[0160] The first determination module 1001 is used to determine the position of the first sending subframe, and take the position of the next physical subframe of the first sending subframe as the starting position; the sending subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal.

[0161] The synchronization signal reception detection module 1002 is used to perform beacon signal reception detection and / or SLSS reception detection on each physical subframe starting from the starting position until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe.

[0162] The synchronization module 1003 is used to perform synchronization according to the synchronization information carried by the physical subframe that has been detected and the first synchronization measurement result obtained by the current measurement.

[0163] In some embodiments, the synchronization signal reception detection module 1002 includes: a beacon signal reception detection unit, configured to perform beacon signal reception detection on each physical subframe before the first timer expires; and / or The SLSS reception detection unit is used to perform SLSS reception detection on each physical subframe before the second timer ends.

[0164] In some embodiments, it also includes: A first starting unit, configured to start the first timer when the terminal device is turned on or starts searching for a synchronization signal; A second starting unit is configured to start the second timer when the first timer times out and no physical subframe is detected by beacon signal reception; and / or The third starting unit is used to start the first timer when the second timer times out and no physical subframe passes the SLSS reception detection.

[0165] In some embodiments, it also includes: A first ending unit, configured to end the first timer in case that there is a physical subframe detected by receiving a beacon signal; A second ending unit, configured to end the first timer when the first timer times out; A third ending unit is configured to end the second timer when there is a physical subframe detected by SLSS reception; and / or The fourth ending unit is used to end the second timer when the second timer times out.

[0166] In some embodiments, the synchronization signal reception detection module 1002 includes: The simultaneous receiving detection unit is used to perform beacon signal receiving detection and SLSS receiving detection on each physical subframe.

[0167] In some embodiments, the synchronization signal reception detection module 1002 includes: A first determination unit is used to determine whether the physical subframe is a reserved subframe for sending SLSS, and perform physical layer side link broadcast channel PSBCH decoding check on the data carried by the physical subframe; A second determining unit is configured to determine that the SLSS reception detection is passed when the physical subframe is a reserved subframe for sending the SLSS and the PSBCH decoding check succeeds; and / or The third determining unit is used to determine that the SLSS reception detection fails when the physical subframe is not a reserved subframe for sending the SLSS or the PSBCH decoding check fails.

[0168] In some embodiments, the first determining unit includes: The first acquisition submodule is used to low-pass filter and down-sample the data carried by the physical subframe to obtain two columns of side link primary synchronization signal PSSS symbols, two columns of side link secondary synchronization signal SSSS symbols and three columns of physical layer side link broadcast channel PSBCH demodulation reference signal DMRS symbols; A second acquisition submodule is used to perform correlation detection according to the PSSS symbol, the SSSS symbol and the PSBCH DMRS symbol to obtain a correlation value; A first determining submodule is configured to determine, when the correlation value is greater than a preset threshold, that the physical subframe is a reserved subframe for sending the SLSS; and / or The second determination submodule is used to determine that the physical subframe is not a reserved subframe for sending SLSS when the correlation value is less than or equal to a preset threshold.

[0169] In some embodiments, the synchronization signal reception detection module 1002 includes: a fourth determination unit, configured to determine whether a physical side link control channel PSCCH signal carried by the physical subframe meets the beacon synchronization signal characteristics, and perform a physical side link shared channel PSSCH decoding check on the data carried by the physical subframe; a fifth determining unit, configured to determine that the beacon signal reception detection passes when the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding verification succeeds; and / or The sixth determination unit is used to determine that the beacon signal reception detection fails when the PSCCH signal does not meet the beacon synchronization signal characteristics or the PSSCH decoding check fails.

[0170] In some embodiments, the first determining module 1001 includes: A detection unit, used to detect the rising edge and falling edge of the power value of the radio frequency data; The second determining unit is used to determine the time domain position corresponding to a group of rising edges and falling edges as the position of the first sending subframe when the interval time between the group of rising edges and falling edges is the length of a sending subframe.

[0171] In some embodiments, it also includes: A first determination module, used to determine whether a synchronization signal is received in a current physical subframe; The synchronization maintenance module is used to clear the value of the first counter when a synchronization signal is received in the current physical subframe, and perform synchronization maintenance based on the synchronization information carried by the synchronization signal.

[0172] In some embodiments, the synchronization maintenance module includes: A first judgment unit, used to judge whether the synchronization level in the synchronization information carried by the beacon synchronization signal is higher than or equal to the current system synchronization level; a first synchronization adjustment unit, configured to update a synchronization measurement result based on the synchronization information carried by the beacon synchronization signal when the synchronization level in the synchronization information is higher than or equal to the current system synchronization level, and synchronize according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result; and / or The second judgment unit is used to judge whether a synchronization signal is received in a next physical subframe when the synchronization level of the beacon synchronization signal is lower than the current system synchronization level.

[0173] In some embodiments, the first synchronization adjustment unit includes: an updating subunit, configured to update a timing estimate according to a timing estimate residual carried by the beacon synchronization signal and a timing estimate in the second synchronization measurement result, and to update a frequency offset estimate according to a frequency offset estimate residual carried by the beacon synchronization signal and a frequency offset estimate in the synchronization measurement result; The synchronization adjustment subunit is used to synchronize according to the updated timing estimate, the updated frequency offset estimate and the synchronization information carried by the beacon synchronization signal.

[0174] In some embodiments, it also includes: A third judgment unit, used to judge whether the subframe number in the synchronization information is equal to the system subframe number; The fourth judgment unit is used to clear the value of the second counter when the subframe number in the synchronization information is equal to the system subframe number, and judge whether the synchronization signal is received in the next physical subframe.

[0175] In some embodiments, the synchronization maintenance module includes: A fifth judgment unit, used to judge whether the subframe number in the synchronization information carried by the SLSS is equal to the system subframe number; The sixth judgment unit is used to clear the value of the second counter when the subframe number in the synchronization information is equal to the system subframe number, and judge whether the synchronization signal is received in the next physical subframe.

[0176] In some embodiments, it also includes: A first judging subunit, configured to, when the subframe number in the synchronization information is not equal to the system subframe number, increase the value of the second counter by one, and judge whether the value of the second counter exceeds a second threshold value; a synchronization subunit, configured to, when the value of the second counter exceeds the second threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or The second judging subunit is configured to judge whether a synchronization signal is received in a next physical subframe when the value of the second counter does not exceed the second threshold value.

[0177] In some embodiments, it also includes: A second judgment module is used to increase the value of the first counter by one when the current physical subframe does not receive the synchronization signal, and judge whether the value of the first counter exceeds a first threshold value; a synchronization execution module, configured to re-determine the position of the first transmitted subframe and perform a synchronization operation when the value of the first counter exceeds the first threshold value; and / or The third judgment module is used to judge whether a synchronization signal is received in a next physical subframe when the value of the first counter does not exceed the first threshold value.

[0178] In some embodiments, it also includes: A fourth determination module, used to determine whether the current physical subframe is a reserved subframe; A second determination module is configured to perform a beacon signal reception detection on the current physical subframe when the current physical subframe is not a reserved subframe, and determine that a beacon synchronization signal is received in the current physical subframe when the beacon signal reception detection passes; and / or The third determination module is used to perform SLSS reception detection on the current physical subframe when the current physical subframe is a reserved subframe, and determine that the SLSS is received in the current physical subframe when the SLSS reception detection passes.

[0179] In some embodiments, the specific steps of performing synchronization include one or more of the following: Adjust the subframe number of the current system according to the subframe number in the synchronization information; adjusting the starting position of the subframe according to the timing estimate in the synchronization measurement result; Adjust the crystal oscillator based on the frequency offset estimate from the synchronous measurement results; Adjust the UTC of the current system according to the coordinated universal time UTC in the synchronization information; Determine the synchronization level of the current system according to the synchronization level in the synchronization information; Calculating a target timing estimate based on the timing estimate residual in the synchronization information and the timing estimate in the synchronization measurement result, and adjusting the starting position of the subframe based on the target timing estimate; Calculating a target frequency offset estimate based on the frequency offset estimate residual in the synchronization information and the frequency offset estimate in the synchronization measurement result, and adjusting the crystal oscillator based on the target frequency offset estimate; and / or Leap seconds are adjusted according to the leap second indication in the sync information.

[0180] Specifically, the above-mentioned joint synchronization device for V2X provided by the present invention can implement all the method steps implemented by the above-mentioned joint synchronization method embodiment for V2X, and can achieve the same technical effect. The parts and beneficial effects that are the same as those in the method embodiment will not be specifically repeated here.

[0181] It should be noted that the division of units / modules in the above-mentioned embodiments of the present invention is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, the functional units in the various embodiments of the present application may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware or in the form of software functional units.

[0182] Fig.11 is a schematic diagram of the structure of the terminal device provided by the present invention, such as Fig.11 As shown, the terminal device may include: a processor 1101, a communications interface 1102, a memory 1103 and a communication bus 1104, wherein the processor 1101, the communications interface 1102, and the memory 1103 communicate with each other through the communication bus 1104. The processor 1101 may call the logic instructions in the memory 1103 to execute a joint synchronization method for V2X, the method comprising: Determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; Starting from the starting position, a beacon signal reception detection and / or an SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; Synchronization is performed according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

[0183] Specifically, the processor 1101 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or a complex programmable logic device (CPLD), and the processor may also adopt a multi-core architecture.

[0184] The logic instructions in the memory 1103 can be implemented in the form of software functional units and can be stored in a processor-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0185] In some embodiments, a computer program product is further provided, the computer program product comprising a computer program, the computer program may be stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer can execute the joint synchronization method for V2X provided in the above-mentioned method embodiments, the method comprising: Determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; Starting from the starting position, a beacon signal reception detection and / or an SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; Synchronization is performed according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

[0186] Specifically, the above-mentioned computer program product provided in the embodiment of the present application can implement all the method steps implemented by the above-mentioned method embodiments, and can achieve the same technical effect. The parts and beneficial effects of this embodiment that are the same as the method embodiment will not be described in detail here.

[0187] In some embodiments, a computer-readable storage medium is further provided, wherein the computer-readable storage medium stores a computer program, wherein the computer program is used to enable a computer to execute the joint synchronization method for V2X provided in the above-mentioned method embodiments, the method comprising: Determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; Starting from the starting position, a beacon signal reception detection and / or an SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; Synchronization is performed according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

[0188] Specifically, the above-mentioned computer-readable storage medium provided by the present invention can implement all the method steps implemented by the above-mentioned method embodiments, and can achieve the same technical effects. The parts and beneficial effects that are the same as the method embodiments in this embodiment will not be described in detail here.

[0189] It should be noted that the computer-readable storage medium can be any available medium or data storage device that can be accessed by the processor, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)), etc.

[0190] It should also be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first" and "second" are usually of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0191] In the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0192] In the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar to them.

[0193] In the present invention, "determine B based on A" means that the factor A should be considered when determining B. It is not limited to "B can be determined based on A alone", but should also include: "determine B based on A and C", "determine B based on A, C and E", "determine C based on A, and further determine B based on C", etc. In addition, it can also include taking A as a condition for determining B, for example, "when A meets the first condition, use the first method to determine B"; for another example, "when A meets the second condition, determine B", etc.; for another example, "when A meets the third condition, determine B based on the first parameter", etc. Of course, it can also be a condition that takes A as a factor for determining B, for example, "when A meets the first condition, use the first method to determine C, and further determine B based on C", etc.

[0194] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program codes.

[0195] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer executable instructions. These computer executable instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0196] These processor executable instructions may also be stored in a processor readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the processor readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0197] These processor-executable instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0198] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A joint synchronization method for V2X, characterized in that: Applied to terminal equipment, including: Determine the position of the first transmission subframe, and use the position of the next physical subframe of the first transmission subframe as the starting position; the transmission subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; Starting from the starting position, a beacon signal reception detection and / or an SLSS reception detection is performed on each physical subframe until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; Synchronization is performed according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

2. The joint synchronization method for V2X according to claim 1, characterized in that: The performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Before the first timer expires, performing beacon signal reception detection on each physical subframe; and / or Before the second timer expires, SLSS reception detection is performed on each physical subframe.

3. The joint synchronization method for V2X according to claim 2, characterized in that: The method further comprises: When the terminal device is turned on or starts searching for a synchronization signal, starting the first timer; When the first timer times out and no physical subframe is detected by beacon signal reception, start the second timer; and / or When the second timer times out and no physical subframe passes SLSS reception detection, the first timer is started.

4. The joint synchronization method for V2X according to claim 2, characterized in that: The method further comprises: In the case where there is a physical subframe detected by receiving a beacon signal, ending the first timer; When the first timer times out, end the first timer; In the case that there is a physical subframe detected by SLSS reception, ending the second timer; and / or When the second timer times out, the second timer is ended.

5. The joint synchronization method for V2X according to claim 1, characterized in that: The performing beacon signal reception detection and / or SLSS reception detection on each physical subframe includes: Beacon signal reception detection and SLSS reception detection are performed on each physical subframe.

6. The joint synchronization method for V2X according to claim 1, 2 or 5, characterized in that: The performing SLSS reception detection on each physical subframe includes: Determine whether the physical subframe is a reserved subframe for sending SLSS, and perform physical layer side link broadcast channel PSBCH decoding check on the data carried by the physical subframe; In a case where the physical subframe is a reserved subframe for sending SLSS and the PSBCH decoding check succeeds, determining that the SLSS reception detection passes; and / or When the physical subframe is not a reserved subframe for sending SLSS, or the PSBCH decoding check fails, it is determined that the SLSS reception detection fails.

7. The joint synchronization method for V2X according to claim 6, characterized in that: The determining whether the physical subframe is a reserved subframe for sending the SLSS includes: Low-pass filtering and down-sampling are performed on the data carried by the physical subframe to obtain two columns of side link primary synchronization signal PSSS symbols, two columns of side link secondary synchronization signal SSSS symbols, and three columns of physical layer side link broadcast channel PSBCH demodulation reference signal DMRS symbols; Perform correlation detection according to the PSSS symbol, the SSSS symbol and the PSBCH DMRS symbol to obtain a correlation value; When the correlation value is greater than a preset threshold, determining that the physical subframe is a reserved subframe for sending the SLSS; and / or When the correlation value is less than or equal to the preset threshold, it is determined that the physical subframe is not a reserved subframe for sending the SLSS.

8. The joint synchronization method for V2X according to claim 1, 2 or 5, characterized in that: Performing beacon signal reception detection on each physical subframe includes: Determine whether a physical side link control channel PSCCH signal carried by the physical subframe meets the beacon synchronization signal characteristics, and perform physical side link shared channel PSSCH decoding check on the data carried by the physical subframe; If the PSCCH signal meets the beacon synchronization signal characteristics and the PSSCH decoding verification is successful, determine that the beacon signal reception detection is passed; and / or When the PSCCH signal does not conform to the beacon synchronization signal characteristics, or the PSSCH decoding check fails, it is determined that the beacon signal reception detection fails.

9. The joint synchronization method for V2X according to claim 1, characterized in that: The determining the position of the first sending subframe includes: Detect the rising edge and falling edge of the power value of the radio frequency data; In the case where the interval time between a group of rising edges and falling edges is the length of a transmission subframe, the time domain position corresponding to the group of rising edges and falling edges is determined as the position of the first transmission subframe.

10. The joint synchronization method for V2X according to claim 1, characterized in that: When the synchronization is completed, the method further includes: Determine whether a synchronization signal is received in the current physical subframe; When the current physical subframe receives a synchronization signal, the value of the first counter is cleared, and synchronization maintenance is performed based on the synchronization information carried by the synchronization signal.

11. The joint synchronization method for V2X according to claim 10, characterized in that: In a case where the synchronization signal is a beacon synchronization signal, the performing synchronization maintenance based on the synchronization information carried by the synchronization signal includes: Determining whether the synchronization level in the synchronization information carried by the beacon synchronization signal is higher than or equal to the current system synchronization level; When the synchronization level in the synchronization information is higher than or equal to the current system synchronization level, updating the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and performing synchronization according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result; and / or In a case where the synchronization level of the beacon synchronization signal is lower than the current system synchronization level, it is determined whether a synchronization signal is received in a next physical subframe.

12. The joint synchronization method for V2X according to claim 11, characterized in that: The updating of the synchronization measurement result based on the synchronization information carried by the beacon synchronization signal, and synchronizing according to the synchronization information carried by the beacon synchronization signal and the updated second synchronization measurement result, includes: updating a timing estimate according to a timing estimate residual carried by the beacon synchronization signal and a timing estimate in the second synchronization measurement result, and updating a frequency offset estimate according to a frequency offset estimate residual carried by the beacon synchronization signal and a frequency offset estimate in the synchronization measurement result; Synchronization is performed based on the updated timing estimate, the updated frequency offset estimate, and the synchronization information carried by the beacon synchronization signal.

13. The joint synchronization method for V2X according to claim 11, characterized in that: In a case where the synchronization level of the beacon synchronization signal is higher than or equal to the current system synchronization level, the method further includes: Determining whether the subframe number in the synchronization information is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

14. The joint synchronization method for V2X according to claim 10, characterized in that: In a case where the synchronization signal is SLSS, the performing synchronization maintenance based on the synchronization information carried by the synchronization signal includes: Determine whether the subframe number in the synchronization information carried by the SLSS is equal to the system subframe number; When the subframe number in the synchronization information is equal to the system subframe number, the value of the second counter is cleared to zero, and it is determined whether a synchronization signal is received in the next physical subframe.

15. The joint synchronization method for V2X according to claim 13 or 14, characterized in that: The method further comprises: When the subframe number in the synchronization information is not equal to the system subframe number, adding one to the value of the second counter, and determining whether the value of the second counter exceeds a second threshold value; When the value of the second counter exceeds the second threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the second counter does not exceed the second threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

16. The joint synchronization method for V2X according to claim 10, characterized in that: The method further comprises: In the case that the current physical subframe does not receive a synchronization signal, adding one to the value of the first counter, and determining whether the value of the first counter exceeds a first threshold value; When the value of the first counter exceeds the first threshold value, re-determine the position of the first transmitted subframe and perform a synchronization operation; and / or When the value of the first counter does not exceed the first threshold value, it is determined whether a synchronization signal is received in a next physical subframe.

17. The joint synchronization method for V2X according to claim 10, characterized in that: The method further comprises: Determine whether the current physical subframe is a reserved subframe; If the current physical subframe is not a reserved subframe, performing a beacon signal reception detection on the current physical subframe, and if the beacon signal reception detection passes, determining that a beacon synchronization signal is received in the current physical subframe; and / or In the case that the current physical subframe is a reserved subframe, an SLSS reception detection is performed on the current physical subframe, and in the case that the SLSS reception detection passes, it is determined that the SLSS is received in the current physical subframe.

18. The joint synchronization method for V2X according to claim 1, 11 or 12, characterized in that: The specific steps of synchronization include one or more of the following: Adjust the subframe number of the current system according to the subframe number in the synchronization information; adjusting the starting position of the subframe according to the timing estimate in the synchronization measurement result; Adjust the crystal oscillator based on the frequency offset estimate from the synchronous measurement results; Adjust the UTC of the current system according to the coordinated universal time UTC in the synchronization information; Determine the synchronization level of the current system according to the synchronization level in the synchronization information; Calculating a target timing estimate based on the timing estimate residual in the synchronization information and the timing estimate in the synchronization measurement result, and adjusting the starting position of the subframe based on the target timing estimate; Calculating a target frequency offset estimate based on the frequency offset estimate residual in the synchronization information and the frequency offset estimate in the synchronization measurement result, and adjusting the crystal oscillator based on the target frequency offset estimate; and / or Leap seconds are adjusted according to the leap second indication in the sync information.

19. A joint synchronization device for V2X, characterized in that: include: A first determining module is used to determine the position of the first transmission subframe, and take the position of the next physical subframe of the first transmission subframe as the starting position; The sending subframe includes a reserved subframe for sending a side link synchronization signal SLSS and / or a logical subframe for sending a beacon synchronization signal; A synchronization signal reception detection module, used to perform a beacon signal reception detection and / or an SLSS reception detection on each physical subframe starting from the starting position until the detection passes; the beacon signal reception detection is used to detect whether there is a beacon synchronization signal on the physical subframe; the SLSS reception detection is used to detect whether there is an SLSS on the physical subframe; The synchronization module is used to perform synchronization according to the synchronization information carried by the physical subframe that has passed the detection and the first synchronization measurement result obtained by the current measurement.

20. A terminal device, characterized in that: Including memory, transceiver, processor; The memory is used to store computer programs; the transceiver is used to send and receive data under the control of the processor; the processor is used to read the computer program in the memory and execute the joint synchronization method for V2X as described in any one of claims 1 to 18.

21. A processor-readable storage medium, characterized in that: The processor-readable storage medium stores a computer program, and when the computer program is executed by the processor, the joint synchronization method for V2X according to any one of claims 1 to 18 is implemented.

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