CN113141594B

CN113141594B - Synchronization method and device and Internet of vehicles V2X equipment

Info

Publication number: CN113141594B
Application number: CN202010054561.5A
Authority: CN
Inventors: 苗玉梅; 周海军; 房家奕
Original assignee: Datang Gaohong Zhilian Technology Chongqing Co ltd
Current assignee: Datang Gaohong Zhilian Technology Chongqing Co ltd
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2022-10-14
Anticipated expiration: 2040-01-17
Also published as: CN113141594A

Abstract

The invention provides a synchronization method, a synchronization device and a vehicle networking V2X device, wherein the synchronization method comprises the following steps: transmitting a PSBCH and/or a preset channel to a second V2X device under the condition that a first V2X device is in a synchronous state; the preset channel comprises a PSCCH and a PSSCH; PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logic subframe, and the logic subframe is a subframe except a reserved subframe. According to the scheme, the second V2X equipment at the receiving side can be supported to directly and effectively realize synchronization between the V2X equipment according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment in the GNSS signal coverage blind area is solved, the desynchronizing phenomenon can be avoided, and traffic safety is maintained; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; the problems that transmission delay of services is increased and synchronization cannot be achieved in a synchronization scheme in the prior art are well solved.

Description

Synchronization method and device and Internet of vehicles V2X equipment

Technical Field

The invention relates to the technical field of terminals, in particular to a synchronization method and device and a vehicle networking V2X device.

Background

With the rapid development of the car networking technology, more and more vehicle-mounted V2X (car networking) devices are coming into use. The vehicle-mounted V2X equipment enables the vehicles to share the traffic information through vehicle-to-vehicle communication, so that the vehicles can acquire relatively comprehensive traffic information in real time, and the safe driving of the vehicles is ensured. The method for keeping synchronization between the ad hoc network V2X devices by utilizing GNSS (global navigation satellite system) signals is a simple and feasible synchronization scheme, but the phenomenon that the GNSS signals are small in intensity or even lost exists in scenes such as tunnels or underground parking lots, so that each vehicle-mounted terminal cannot synchronize through the GNSS signals, further the vehicle-mounted terminal cannot acquire various communication information in a vehicle networking, and the traffic safety of vehicles is threatened.

In order to solve the above problem, the prior art provides a solution: in the existing LTE (long term evolution) -V2X standard, a synchronization channel is specifically set up to transmit a synchronization signal, and the synchronization channel is called a PSBCH channel (bypass broadcast channel). The synchronization period is the standard of 160ms, and a certain subframe resource is configured in the 160ms period for transmitting the PSBCH and the SLSS signal (bypass synchronization signal), and data of the traffic channel cannot be transmitted in these subframes.

Specifically, consider: the synchronization period needs to be divided by 10240, the overhead of synchronization information transmission, and the synchronization period matches the length of 100ms of a typical traffic period, so the synchronization period is defined as 160ms. Wherein:

1) Number of synchronization subframes:

if the existing requirement exists, when the synchronization message is sent out of the coverage, at least 2 synchronization subframes are set, since the synchronization period is 160ms, 64 synchronization periods exist in the system frame 10240, 128 synchronization subframes are occupied totally, and the overhead is 1.25%.

2) And (3) defining a reserved subframe:

because the system frame length is 10240, synchronous subframes, and downlink subframes and special subframes of TDD (time division duplex) are excluded, and the remaining subframes after the modulus of the remaining subframes by a high-level configuration bitmap are reserved subframes.

3) The number of reserved subframes is as follows:

because bitmap is only considered to be set to be 100ms, if the synchronization period is 160ms and the number of synchronization subframes is 128, the number of reserved subframes is: (10240-128) mod (remainder) 100=12; the reserved subframe overhead is 0.1%.

In the case where no synchronization subframe is set, the number of reserved subframes is (10240) mod 100=40.

4) Distribution of reserved subframes within a system frame:

in the system frame 10240, the reserved subframes are distributed evenly according to the number of the reserved subframes.

5) Physical subframe number:

each subframe within the subframes of system frame 10240 is numbered, ranging from 0 to 10239, which is the physical subframe number.

6) Logical subframe number:

each unreserved subframe in the subframes of the system frame 10240 is numbered, and under the condition that the synchronous subframe is not set, the range is 0-10199, which is a logical subframe number.

7) DMRS (demodulation reference signal) pilot signal:

for both LTE-V2X system and NR (new air interface) -V2X system, when PSCCH (bypass control channel) or PSCCH (bypass shared channel) is transmitted, DMRS signals are transmitted at the same time for PSCCH detection on the receiving side, a specific sequence is required to be used when DMRS signals are generated, and initial parameters of the generated sequence are reset every 10 logical subframes.

The existence of the synchronous sub-frame can solve the problem of synchronization of vehicle-to-vehicle communication without GNSS signals, but increases resource overhead and service time delay.

From the above, it can be seen that:

1) In the existing LTE-V2X standard, synchronization between V2X devices is ensured by reserving a synchronization subframe and transmitting a PSBCH channel, which has the following disadvantages: the total overhead of the synchronization sub-frame and the reserved sub-frame is 1.35%, and the overhead can increase the transmission delay of the service and reduce the transmission efficiency.

2) If the GNSS signals are directly utilized for synchronization, although the complexity of product implementation can be reduced, there are disadvantages: in GNSS signal coverage blind areas such as tunnels and underground parking lots, the V2X equipment cannot receive GNSS signals, the equipment is out of step, normal service communication cannot be carried out between the equipment, and traffic information under the scene cannot be acquired, so that traffic safety hazards are caused.

It can be known from the above that the existing synchronization scheme has the problems of requiring additional time-frequency resource overhead, increasing transmission delay of the service, being unable to implement synchronization, etc.

Disclosure of Invention

The invention aims to provide a synchronization method, a synchronization device and Internet of vehicles V2X equipment, and aims to solve the problems that in the prior art, the transmission delay of a service is increased and synchronization cannot be realized in a synchronization scheme.

In order to solve the above technical problem, an embodiment of the present invention provides a synchronization method, which is applied to a first vehicle networking V2X device, where the first V2X device includes a road side unit RSU or a vehicle mounted unit OBU, and the synchronization method includes:

transmitting a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device under the condition that the first V2X device is in a synchronous state;

the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH;

the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe;

the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logic subframe, and the logic subframe is a subframe except the reserved subframe.

Optionally, the synchronization control indication information includes:

subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether a synchronization control signaling is carried in the PSCCH and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH;

wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10);

or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indication value is a non-zero value;

or, the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of mod (n, 10) are divided into m groups, one indication value corresponds to a group of possible values of mod (n, 10), m <10; the indication value is a non-zero value;

and when the indicated value is a nonzero value, indicating that the PSCCH carries the synchronous control signaling.

Optionally, the synchronization control indication information further includes: 2 bits of synchronization level information, wherein the bits of the synchronization level information: if the value is 01, the first V2X equipment is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

Optionally, the synchronization control indication information further includes:

1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission and the initial transmitted physical subframe when the PSSCH retransmission is enabled.

Optionally, when the retransmission of the PSSCH is disabled, the indication flag information is invalid, and a bit indication value of the indication flag information is 0.

Optionally, the PSBCH further carries the synchronization level of the first V2X device.

Optionally, information carried by the PSCCH and the PSCCH is collectively referred to as quasi-synchronization information.

Optionally, before sending the bypass broadcast channel PSBCH and/or the preset channel to the second V2X device, the method further includes:

searching GNSS information, synchronous information and quasi-synchronous information of a global navigation satellite system in each subframe;

and under the condition that the first V2X device is in a synchronous state, determining the synchronous level of the first V2X device according to a search result.

Optionally, the determining, according to the search result, the synchronization level of the first V2X device includes:

determining that the synchronization level of the first V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information;

or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a fifth V2X device with a synchronization level of 2 is searched, and synchronization with the fifth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 3;

or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a sixth V2X device with a synchronization level of 3 or 4 is searched, and synchronization with the sixth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 4.

Optionally, the PSBCH also carries greenwich UTC time.

The embodiment of the invention also provides a synchronization method, which is applied to a second vehicle networking V2X device, wherein the second V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method comprises the following steps:

receiving a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device;

carrying out synchronization according to the PSBCH and/or a preset channel;

the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe.

Optionally, the synchronization control indication information includes:

subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH;

wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of mod (n, 10);

or the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of the mod (n, 10) are divided into m groups, one of the indication values corresponds to a group of possible values of the mod (n, 10), m <10; the indication value is a non-zero value;

Optionally, the synchronization control indication information further includes: 2 bits of synchronization level information, wherein bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

Optionally, the synchronizing according to the PSBCH and/or a preset channel includes:

under the condition that the second V2X equipment is in an out-of-step state or a quasi-synchronization state, synchronizing according to the PSBCH and/or a preset channel;

or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel;

or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel.

Optionally, before performing synchronization according to the PSBCH and/or a preset channel when the second V2X device is in a synchronous state or a quasi-synchronous state, the method further includes:

and under the condition that the second V2X device is in a synchronous state, determining the synchronous level of the second V2X device according to the search result.

Optionally, the determining, according to the search result, the synchronization level of the second V2X device includes:

determining that the synchronization level of the second V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information;

or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a seventh V2X device with a synchronization level of 2 is searched, and synchronization with the seventh V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 3;

or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by an eighth V2X device having a synchronization level of 3 or 4 is searched, and synchronization with the eighth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 4.

Optionally, the synchronizing according to the preset channel includes:

detecting the PSCCH according to the preliminary timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information;

determining a value of mod (n, 10) based on the indication value of the first bit;

obtaining a local pilot frequency numerical value of the PSSCH according to the synchronous control signaling, the CRC check bit information and the mod (n, 10) value;

detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining the timing offset of a subframe head according to a pilot signal of the PSSCH and a demodulation reference signal (DMRS) after the decoding is successful;

and obtaining the timing position of the subframe head according to the preliminary timing position and the timing offset of the subframe head, and entering a quasi-synchronization state.

Optionally, the determining a value of mod (n, 10) according to the indication value of the first bit includes:

under the condition that the number of the first bits is 1 and the indication value of the first bits is 1, blind-detecting all possible values of the mod (n, 10), and obtaining a unique mod (n, 10) value after the blind-detection is successful;

or, in the case that the number of bits of the first bit is 4 and the indication value of the first bit is a non-zero value, subtracting 1 from the indication value to obtain the value of mod (n, 10);

or, when the number of bits of the first bit is 2 or 3 and the indication value of the first bit is a non-zero value, determining possible values of mod (n, 10) of the corresponding group according to the indication value, performing blind detection on each possible value of mod (n, 10), and obtaining a unique mod (n, 10) value after the blind detection is successful.

Optionally, before detecting the PSCCH according to the preliminary timing position of the subframe header to obtain the synchronization control signaling and the CRC check bit information, the method further includes:

when the second V2X equipment is in the out-of-step state, obtaining the preliminary timing position according to the data characteristics of the quasi-synchronization information, and entering the quasi-synchronization state from the out-of-step state;

or, when the second V2X device is in a synchronous state or a quasi-synchronous state, acquiring and storing the preliminary timing position.

Optionally, the synchronization information includes a radio frame number and a subframe number; according to the PSBCH, synchronization is carried out, and the method comprises the following steps:

obtaining a physical subframe number of the second V2X device according to the radio frame number and the subframe number;

and correcting time and frequency according to the timing position of the subframe header and the physical subframe number, keeping synchronization with the first V2X equipment, and entering a synchronization state.

Optionally, when the retransmission of the PSSCH is not enabled, the indication flag information is invalid, and a bit indication value of the indication flag information is 0.

Optionally, the detecting and decoding the PSSCH according to the local pilot frequency value includes:

if the PSSCH decoding is successful but the PSSCH decoding is failed, obtaining a physical subframe interval between the first transmission and the retransmission of the PSSCH based on a logical subframe interval between the first transmission and the retransmission of the PSSCH indicated by the PSCCH and the indication mark information, and carrying out combined decoding on the PSSCH according to the physical subframe interval.

Optionally, the synchronizing is performed according to the preset channel, and the method further includes:

obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of a crystal oscillator adjustment counter;

and carrying out crystal oscillator synchronization according to the crystal oscillator adjustment amount.

Optionally, the synchronizing according to the PSBCH and/or a preset channel further includes:

determining a synchronization level of the second V2X device according to a synchronization level of the first V2X device carried by the PSBCH under the condition that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state;

or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel;

or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel.

Optionally, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the determining, according to the synchronization level of the first V2X device carried by the PSBCH, the synchronization level of the second V2X device includes:

determining that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the first V2X device is the lowest synchronization level;

or, in a case that the synchronization level of the first V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel includes:

determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel includes:

determining that the synchronization level of the second V2X device is the lowest synchronization level, when the synchronization level of the second V2X device is the lowest synchronization level;

or, in case that the synchronization level of the second V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, before receiving the bypass broadcast channel PSBCH and/or the preset channel sent by the first V2X device, the method further includes:

entering an out-of-synchronization state when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the PSBCH and/or the preset channel sent by the ninth V2X device are not received within a preset time period; the ninth V2X device has a higher synchronization level than the second V2X device;

or, when the second V2X device is in a synchronization state and the synchronization level of the second V2X device is the lowest synchronization level and does not receive the PSBCH and/or the preset channel sent by the tenth V2X device within the preset time period, entering an out-of-synchronization state; the synchronization level of the tenth V2X device is not lower than the synchronization level of the second V2X device;

or, entering an out-of-synchronization state when the second V2X device is in a quasi-synchronization state and does not receive the PSBCH and/or the preset channel sent by the eleventh V2X device within a preset time period.

Optionally, the PSBCH further carries greenwich UTC time.

The embodiment of the invention also provides a vehicle networking V2X device, wherein the V2X device is a first V2X device, the first V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the device further comprises a memory, a processor, a transceiver and a computer program which is stored on the memory and can run on the processor; the processor implements the following steps when executing the program:

transmitting a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device through the transceiver under the condition that the first V2X device is in a synchronous state;

Optionally, the synchronization control indication information includes:

and when the indicated value is a non-zero value, indicating that the PSCCH carries the synchronous control signaling.

Optionally, the synchronization control indication information further includes: 2 bits of synchronization level information, wherein the bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

Optionally, the processor is further configured to:

before transmitting a bypass broadcast channel PSBCH and/or a preset channel to the second V2X device, searching Global Navigation Satellite System (GNSS) information, synchronization information and quasi-synchronization information in each subframe;

Optionally, the processor is specifically configured to:

Optionally, the PSBCH further carries greenwich UTC time.

The embodiment of the invention also provides a vehicle networking V2X device, wherein the V2X device is a second V2X device, the second V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the device further comprises a memory, a processor, a transceiver and a computer program which is stored on the memory and can run on the processor; the processor implements the following steps when executing the program:

receiving, by the transceiver, a bypass broadcast channel PSBCH and/or a preset channel transmitted by a first V2X device;

carrying out synchronization according to the PSBCH and/or a preset channel;

Optionally, the synchronization control indication information includes:

or the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of the mod (n, 10) are divided into m groups, one of the indication values corresponds to a group of possible values of the mod (n, 10), m <10; the indicated value is a non-zero value;

Optionally, the processor is specifically configured to:

Optionally, the processor is further configured to:

searching Global Navigation Satellite System (GNSS) information, synchronization information and quasi-synchronization information in each subframe before synchronization is carried out according to the PSBCH and/or a preset channel when the second V2X equipment is in a synchronization state or a quasi-synchronization state;

and under the condition that the second V2X device is in a synchronous state, determining the synchronization level of the second V2X device according to the search result.

Optionally, the processor is specifically configured to:

detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining a subframe head timing offset according to a pilot signal of the PSSCH and a demodulation reference signal (DMRS) after the decoding is successful;

Optionally, the processor is specifically configured to:

blind-detecting all possible values of the mod (n, 10) under the condition that the number of bits of the first bit is 1 and the indication value of the first bit is 1, and obtaining a unique mod (n, 10) value after the blind-detection is successful;

or, when the number of bits of the first bit is 2 or 3 and the indication value of the first bit is a non-zero value, determining possible values of the mod (n, 10) of the corresponding group according to the indication value, performing blind detection on each possible value of the mod (n, 10), and obtaining a unique mod (n, 10) value after the blind detection is successful.

Optionally, the processor is further configured to:

before the PSCCH is detected according to the preliminary timing position of the subframe header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information, when the second V2X equipment is in an out-of-step state, the preliminary timing position is obtained according to the data characteristics of the quasi-synchronous information, and the out-of-step state enters a quasi-synchronous state;

Optionally, the synchronization information includes a radio frame number and a subframe number; the processor is specifically configured to:

1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission enabled by PSSCH retransmission and the initial transmitted physical subframe.

Optionally, the processor is specifically configured to:

Optionally, the processor is further configured to:

obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of the crystal oscillator adjustment counter;

Optionally, the processor is further configured to:

Optionally, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the processor is specifically configured to:

or, in case that the synchronization level of the first V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, when the second V2X device is in a synchronization state, the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the processor is specifically configured to:

Optionally, when the second V2X device is in a synchronization state, the synchronization level of the second V2X device is a lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the processor is specifically configured to:

or, in a case that the synchronization level of the second V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, the processor is further configured to:

before receiving a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device, when a second V2X device is in a synchronous state, the synchronous grade of the second V2X device is not the lowest synchronous grade, and the PSBCH and/or the preset channel sent by a ninth V2X device are not received in a preset time period, entering an out-of-synchronization state; the ninth V2X device has a higher synchronization level than the second V2X device;

Optionally, the PSBCH further carries greenwich UTC time.

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the synchronization method on the first V2X device side; alternatively, the first and second electrodes may be,

the program, when executed by a processor, implements the steps of the synchronization method of the second V2X device described above.

The embodiment of the present invention further provides a synchronization apparatus, which is applied to a first vehicle networking V2X device, where the first V2X device includes a road side unit RSU or a vehicle side unit OBU, and the synchronization apparatus includes:

a first sending module, configured to send a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device when the first V2X device is in a synchronization state;

Optionally, the synchronization control indication information includes:

Optionally, the method further includes:

a first searching module, configured to search for global navigation satellite system GNSS information, synchronization information, and quasi-synchronization information at each subframe before transmitting a bypass broadcast channel PSBCH and/or a preset channel to the second V2X device;

a first determining module, configured to determine, according to a search result, a synchronization level of the first V2X device when the first V2X device is in a synchronization state.

Optionally, the first determining module includes:

the first determining submodule is used for determining that the synchronization level of the first V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information;

Optionally, the PSBCH also carries greenwich UTC time.

The embodiment of the present invention further provides a synchronization apparatus, which is applied to a second vehicle networking V2X device, where the second V2X device includes a road side unit RSU or a vehicle-mounted unit OBU, and the synchronization apparatus includes:

a first receiving module, configured to receive a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device;

a first synchronization module, configured to perform synchronization according to the PSBCH and/or a preset channel;

Optionally, the synchronization control indication information includes:

Optionally, the first synchronization module includes:

a first synchronization sub-module, configured to perform synchronization according to the PSBCH and/or a preset channel when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state;

Optionally, the method further includes:

a second search module, configured to search for GNSS information, synchronization information, and quasi-synchronization information of a global satellite navigation system in each subframe before synchronization is performed according to the PSBCH and/or a preset channel when the second V2X device is in a synchronous state or a quasi-synchronous state;

a second determining module, configured to determine, according to a search result, a synchronization level of the second V2X device when the second V2X device is in a synchronization state.

Optionally, the second determining module includes:

the second determining submodule is used for determining that the synchronization level of the second V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information;

Optionally, the first synchronization module includes:

the first processing sub-module is used for detecting the PSCCH according to the preliminary timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information;

a second processing submodule for determining a value of mod (n, 10) from an indication of the first bit;

a third processing sub-module, configured to obtain a local pilot value of the PSSCH according to the synchronization control signaling, CRC check bit information, and a mod (n, 10) value;

the fourth processing sub-module is used for detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining the timing offset of a subframe head according to the pilot signal of the PSSCH and the DMRS (demodulation reference signal) after the decoding is successful;

and the fifth processing submodule is used for obtaining the timing position of the sub-frame header according to the preliminary timing position and the timing offset of the sub-frame header and entering a quasi-synchronization state.

Optionally, the second processing sub-module includes:

a first processing unit, configured to blindly detect all possible values of mod (n, 10) when a bit number of the first bit is 1 and an indication value of the first bit is 1, and obtain a unique mod (n, 10) value after successful blind detection;

Optionally, the method further includes:

the first processing module is used for detecting the PSCCH according to the preliminary timing position of the subframe header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information, and obtaining the preliminary timing position according to the data characteristics of the quasi-synchronization information when the second V2X equipment is in an out-of-synchronization state, and entering the quasi-synchronization state from the out-of-synchronization state;

Optionally, the synchronization information includes a radio frame number and a subframe number; the first synchronization module includes:

a sixth processing submodule, configured to obtain a physical subframe number of the second V2X device according to the radio frame number and the subframe number;

and the seventh processing submodule is used for correcting time and frequency according to the timing position of the subframe head and the physical subframe number, keeping synchronization with the first V2X equipment and entering a synchronization state.

Optionally, the fourth processing sub-module includes:

and the second processing unit is used for obtaining a physical subframe interval between the first transmission and the retransmission of the PSSCH based on the logical subframe interval between the first transmission and the retransmission of the PSSCH indicated by the PSCCH and the indication mark information if the PSSCH is successfully decoded but the PSSCH is unsuccessfully decoded, and performing combined decoding of the PSSCH according to the physical subframe interval.

Optionally, the first synchronization module further includes:

the eighth processing submodule is used for obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of the crystal oscillator adjustment counter;

and the ninth processing submodule is used for carrying out crystal oscillator synchronization according to the crystal oscillator adjustment quantity.

Optionally, the first synchronization module further includes:

a third determining submodule, configured to determine, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, a synchronization level of the second V2X device according to a synchronization level of the first V2X device carried by the PSBCH;

or, a fourth determining sub-module, configured to, when the second V2X device is in a synchronization state, and a synchronization level of the second V2X device is not a lowest synchronization level, and a synchronization level of the first V2X device is higher than a synchronization level of the second V2X device, re-determine the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel;

or, the fifth determining sub-module is configured to, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, re-determine the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel.

Optionally, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the third determining sub-module includes:

a first determining unit, configured to determine that the synchronization level of the second V2X device is a lowest synchronization level when the synchronization level of the first V2X device is the lowest synchronization level;

Optionally, when the second V2X device is in a synchronization state, the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the fourth determining sub-module includes:

a second determination unit for determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Optionally, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the fifth determining sub-module includes:

a third determining unit, configured to determine that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the second V2X device is the lowest synchronization level;

Optionally, the method further includes:

a second processing module, configured to, before receiving a PSBCH and/or a preset channel that is a bypass broadcast channel and is sent by a first V2X device, enter an out-of-sync state when the second V2X device is in a synchronization state, and a synchronization level of the second V2X device is not a lowest synchronization level, and a PSBCH and/or the preset channel that is sent by a ninth V2X device is not received within a preset time period; the ninth V2X device has a higher synchronization level than the second V2X device;

Optionally, the PSBCH further carries greenwich UTC time.

The technical scheme of the invention has the following beneficial effects:

in the above scheme, the synchronization method is applied to a first vehicle networking V2X device, where the first V2X device includes a road side unit RSU or a vehicle mounted unit OBU, and the synchronization method transmits a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device when the first V2X device is in a synchronization state; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the second V2X equipment on the receiving side can be supported to directly and effectively realize synchronization between the V2X equipment according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment in a GNSS signal coverage blind area is solved, the occurrence of desynchronization phenomenon can be avoided, traffic safety is maintained, meanwhile, the scheme that the V2X equipment utilizes the GNSS signal to carry out synchronization is more complete, communication (synchronization) between the V2X equipment can be ensured to be normally carried out in any scene, and therefore potential traffic safety hazards are reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Drawings

FIG. 1 is a first flowchart illustrating a synchronization method according to an embodiment of the present invention;

FIG. 2 is a second flowchart illustrating a synchronization method according to an embodiment of the present invention;

FIG. 3 is a first flowchart illustrating a specific application of a synchronization method according to an embodiment of the present invention;

FIG. 4 is a flowchart illustrating a second specific application of the synchronization method according to the embodiment of the present invention;

fig. 5 is a schematic diagram of a specific application flow of the synchronization method according to the embodiment of the present invention;

fig. 6 is a schematic diagram illustrating a specific application flow of the synchronization method according to the embodiment of the present invention;

FIG. 7 is a clock propagation diagram according to an embodiment of the present invention;

FIG. 8 is a data feature diagram of an embodiment of the present invention;

fig. 9 is a schematic structural diagram of a first V2X device according to an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a second V2X device according to an embodiment of the present invention;

FIG. 11 is a first schematic structural diagram of a synchronization apparatus according to an embodiment of the present invention;

fig. 12 is a second structural diagram of a synchronization apparatus according to an embodiment of the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The invention provides a synchronization method for solving the problems of increased service transmission delay and incapability of realizing synchronization in a synchronization scheme in the prior art, which is applied to a first vehicle networking (V2X) device, wherein the first V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and as shown in figure 1, the synchronization method comprises the following steps:

step 11: transmitting a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device under the condition that the first V2X device is in a synchronous state; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe.

The synchronization method provided by the embodiment of the invention is applied to first vehicle networking V2X equipment, wherein the first V2X equipment comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method transmits a bypass broadcast channel (PSBCH) and/or a preset channel to second V2X equipment under the condition that the first V2X equipment is in a synchronization state; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the second V2X equipment on the receiving side can be supported to directly and effectively realize synchronization between the V2X equipment according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment in a GNSS signal coverage blind area is solved, the occurrence of desynchronizing phenomenon can be avoided, traffic safety is maintained, meanwhile, the scheme that the V2X equipment utilizes the GNSS signal to carry out synchronization is more complete, communication (synchronization) between the V2X equipment can be ensured to be normally carried out in any scene, and thus the traffic safety potential is reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indicated value is a non-zero value; or the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of the mod (n, 10) are divided into m groups, one of the indication values corresponds to a group of possible values of the mod (n, 10), m <10; the indication value is a non-zero value; and when the indicated value is a nonzero value, indicating that the PSCCH carries the synchronous control signaling.

Regarding the group number of the m groups, in the embodiment of the present invention, a non-zero value is taken.

Further, the synchronization control indication information further includes: 2 bits of synchronization level information, wherein bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

Further, the synchronization control indication information further includes: 1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission enabled by PSSCH retransmission and the initial transmitted physical subframe.

When the retransmission of the PSSCH is not enabled, the indication mark information is invalid, and a bit indication value of the indication mark information is 0.

Further, the PSBCH also carries the synchronization level of the first V2X device.

In the embodiment of the invention, the information carried by the PSCCH and the PSSCH is commonly called as quasi-synchronization information.

Further, before transmitting the bypass broadcast channel PSBCH and/or the preset channel to the second V2X device, the method further includes: searching GNSS information, synchronous information and quasi-synchronous information of a global navigation satellite system in each subframe; and under the condition that the first V2X device is in a synchronous state, determining the synchronous level of the first V2X device according to a search result.

Specifically, the determining the synchronization level of the first V2X device according to the search result includes: determining that the synchronization level of the first V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a fifth V2X device with a synchronization level of 2 is searched, and synchronization with the fifth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a sixth V2X device with a synchronization level of 3 or 4 is searched, and synchronization with the sixth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 4.

In the embodiment of the invention, the PSBCH also carries Greenwich UTC time.

An embodiment of the present invention further provides a synchronization method, which is applied to a second vehicle networking V2X device, where the second V2X device includes a road side unit RSU or a vehicle mounted unit OBU, and as shown in fig. 2, the synchronization method includes:

step 21: receiving a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device;

step 22: carrying out synchronization according to the PSBCH and/or a preset channel; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe.

The synchronization method provided by the embodiment of the invention is applied to a second vehicle networking V2X device, wherein the second V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method receives a bypass broadcast channel (PSBCH) and/or a preset channel sent by a first V2X device; carrying out synchronization according to the PSBCH and/or a preset channel; the preset channel comprises a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the synchronization between the V2X equipment can be effectively realized directly according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment covering a blind area by the GNSS signal is solved, the occurrence of desynchronization can be avoided, the traffic safety is maintained, meanwhile, the scheme for synchronizing the V2X equipment by the GNSS signal is more complete, the communication (synchronization) between the V2X equipment can be normally carried out in any scene, and the traffic safety hidden danger is reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each indication value corresponds to the sum of all possible values of mod (n, 10) plus 1 in a one-to-one manner; the indicated value is a non-zero value; or the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of the mod (n, 10) are divided into m groups, one of the indication values corresponds to a group of possible values of the mod (n, 10), m <10; the indication value is a non-zero value; and when the indicated value is a non-zero value, indicating that the PSCCH carries the synchronous control signaling.

Further, the synchronization control indication information further includes: 2 bits of synchronization level information, wherein the bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

The PSBCH also carries the synchronization level of the first V2X device.

Specifically, the synchronizing according to the PSBCH and/or a preset channel includes: under the condition that the second V2X equipment is in an out-of-step state or a quasi-synchronization state, synchronizing according to the PSBCH and/or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel.

In the embodiment of the invention, the information carried by the PSCCH and the PSSCH is commonly called quasi-synchronization information.

Further, before performing synchronization according to the PSBCH and/or a preset channel when the second V2X device is in a synchronization state or a quasi-synchronization state, the method further includes: searching GNSS information, synchronous information and quasi-synchronous information of a global navigation satellite system in each subframe; and under the condition that the second V2X device is in a synchronous state, determining the synchronous level of the second V2X device according to the search result.

Specifically, the determining the synchronization level of the second V2X device according to the search result includes: determining that the synchronization level of the second V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a seventh V2X device with a synchronization level of 2 is searched, and synchronization with the seventh V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by an eighth V2X device having a synchronization level of 3 or 4 is searched, and synchronization with the eighth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 4.

Wherein, according to the preset channel, the synchronization comprises: detecting the PSCCH according to the preliminary timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information; determining a value of mod (n, 10) based on the indication value of the first bit; obtaining a local pilot frequency numerical value of the PSSCH according to the synchronous control signaling, the CRC check bit information and the mod (n, 10) value; detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining a subframe head timing offset according to a pilot signal of the PSSCH and a demodulation reference signal (DMRS) after the decoding is successful; and obtaining the timing position of the subframe head according to the preliminary timing position and the timing offset of the subframe head, and entering a quasi-synchronization state.

The "obtaining the subframe head timing offset according to the pilot signal of the PSSCH and the DMRS may be specifically implemented as follows: correlating the pilot signal of the PSSCH with a demodulation reference signal (DMRS), and processing the correlation result to obtain a subframe header timing offset with higher accuracy;

thereby to follow: and obtaining the timing position of the subframe head with higher precision according to the preliminary timing position and the timing offset of the subframe head, and entering a quasi-synchronization state.

In this embodiment of the present invention, the determining a value of mod (n, 10) according to the indication value of the first bit includes: blind-detecting all possible values of the mod (n, 10) under the condition that the number of bits of the first bit is 1 and the indication value of the first bit is 1, and obtaining a unique mod (n, 10) value after the blind-detection is successful; or, in the case that the number of bits of the first bit is 4 and the indication value of the first bit is a non-zero value, subtracting 1 from the indication value to obtain the value of mod (n, 10); or, when the number of bits of the first bit is 2 or 3 and the indication value of the first bit is a non-zero value, determining possible values of the mod (n, 10) of the corresponding group according to the indication value, performing blind detection on each possible value of the mod (n, 10), and obtaining a unique mod (n, 10) value after the blind detection is successful.

Further, before detecting the PSCCH according to the preliminary timing position of the subframe header to obtain the synchronization control signaling and the CRC check bit information, the method further includes: when the second V2X equipment is in the out-of-step state, obtaining the preliminary timing position according to the data characteristics of the quasi-synchronization information, and entering the quasi-synchronization state from the out-of-step state; or, when the second V2X device is in a synchronous state or a quasi-synchronous state, acquiring and storing the preliminary timing position.

Wherein the synchronization information comprises a radio frame number and a subframe number; according to the PSBCH, synchronization is carried out, and the method comprises the following steps: obtaining a physical subframe number of the second V2X device according to the radio frame number and the subframe number; and correcting time and frequency according to the timing position of the subframe header and the physical subframe number, keeping synchronization with the first V2X equipment, and entering a synchronization state.

In this embodiment of the present invention, the synchronization control indication information further includes: 1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission physical subframe and an initial transmission physical subframe when the PSSCH is enabled for retransmission; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission and the initial transmitted physical subframe when the PSSCH retransmission is enabled.

When the PSSCH is not enabled for retransmission, the indication mark information is invalid, and the bit indication value of the indication mark information is 0.

Specifically, the detecting and decoding the PSSCH according to the local pilot value includes: if the PSSCH decoding is successful but the PSSCH decoding is failed, obtaining a physical subframe interval between the first transmission and the retransmission of the PSSCH based on a logical subframe interval between the first transmission and the retransmission of the PSSCH indicated by the PSCCH and the indication mark information, and carrying out combined decoding on the PSSCH according to the physical subframe interval.

Further, according to the preset channel, performing synchronization, further comprising: obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of a crystal oscillator adjustment counter; and carrying out crystal oscillator synchronization according to the crystal oscillator adjustment amount.

In this embodiment of the present invention, the synchronizing according to the PSBCH and/or a preset channel further includes: determining a synchronization level of the second V2X device according to a synchronization level of the first V2X device carried by the PSBCH under the condition that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel.

Wherein, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH includes: determining that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the first V2X device is the lowest synchronization level; or, in a case that the synchronization level of the first V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel includes: determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is a lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel includes: determining that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the second V2X device is the lowest synchronization level; or, in a case that the synchronization level of the second V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Further, before receiving the bypass broadcast channel PSBCH and/or the preset channel sent by the first V2X device, the method further includes: entering an out-of-sync state when the second V2X device is in a sync state, and the sync level of the second V2X device is not the lowest sync level, and the PSBCH and/or the preset channel sent by the ninth V2X device are not received within a preset time period; the ninth V2X device has a higher synchronization level than the second V2X device; or, when the second V2X device is in a synchronization state and the synchronization level of the second V2X device is the lowest synchronization level and does not receive the PSBCH and/or the preset channel sent by the tenth V2X device within the preset time period, entering an out-of-synchronization state; the synchronization level of the tenth V2X device is not lower than the synchronization level of the second V2X device; or, entering an out-of-synchronization state when the second V2X device is in a quasi-synchronization state and does not receive the PSBCH and/or the preset channel sent by the eleventh V2X device within a preset time period.

In the embodiment of the invention, the PSBCH also carries greenwich UTC time.

In this description, in the embodiment of the present invention, the receiving side (i.e., the second V2X device side) may realize the transmitting side (i.e., the first V2X device side) as well, and correspondingly, the transmitting side (i.e., the first V2X device side) may realize the receiving side (i.e., the second V2X device side) as well, which is not limited herein.

The synchronization method provided by the embodiment of the present invention is further described below with reference to two sides of the first V2X device and the second V2X device.

In view of the above technical problems, embodiments of the present invention provide a synchronization method, which can be specifically understood as a new synchronization mechanism to solve the problem of step-out of a vehicle networking terminal in a GNSS signal coverage blind area, avoid the occurrence of step-out phenomenon, and maintain traffic safety; furthermore, the scheme can solve the problem of synchronization of the V2X equipment of the GNSS signal coverage blind area on the basis of reducing service time delay, and meanwhile, the scheme that the V2X equipment utilizes the GNSS signal to carry out synchronization is more complete, so that communication between the V2X equipment can be normally carried out in any scene, and the potential traffic safety hazard is reduced.

Specifically, in order to solve the problem of synchronization between V2X devices without GNSS signals, reduce resource overhead, and ensure timely and accurate transmission of service data, embodiments of the present invention provide a synchronization method, in which a special synchronization subframe is not required to be established, DMRS pilot signals and synchronization control signaling respectively carried by PSCCH and PSCCH channels are directly used for synchronization, and synchronization between V2X devices can be effectively achieved.

When the scheme is implemented:

the first V2X device may be installed in a GNSS signal coverage blind area, and the first V2X device transmits traffic channel data of a special configuration (bandwidth is equivalent) at a certain frequency (the period cannot be too long) (PSCCH and PSCCH are one-to-one, and in the same subframe, frequency domain resources are not different); meanwhile, a synchronization control signaling is sent on the PSCCH, and after receiving data of the control channel (i.e., PSCCH) and the traffic channel (i.e., PSCCH), the first V2X device directly uses DMRS pilot data of the traffic channel and the synchronization control signaling carried by the control channel to perform synchronization. The specific processing of the nodes involved on the transmitting side (i.e. the first V2X device side) and the receiving side (i.e. the second V2X device side) is as follows:

transmitting side

1) All the first V2X devices in the synchronization state can send a PSCCH carrying synchronization control indication information, a subframe for sending the special PSCCH can be a logical subframe, and the subframe for sending the PSBCH is limited to a reserved subframe.

2) The synchronization control signaling is carried by the PSCCH at the physical layer.

3) The synchronization control indication information comprises 1-4 bit subframe information and is used for indicating whether the current PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 by a logical word frame number n of the PSSCH; since the PSCCH can carry 32-bit control signaling at most, and at least 7 bits are padding bits at present, the synchronization control indication information can be stored using the padding bit positions of the control signaling carried by the PSCCH. The bits occupied by the subframe information are at least 1 bit and at most 4 bits, and specifically, see examples 1 to 3 described below.

Regarding the value of mod (n, 10), it can be: the value of mod (n, 10) explicitly indicated by the transmitting side or the value of mod (n, 10) blind detected by the receiving side is 2 extremes, and of course, a combination of the two (partial explicit indication + partial blind detection) may respectively correspond to example 3 (explicit), example 1 (blind detection), and example 2 (combination) in sequence.

Further, the synchronization control indication information may further include: whether indication mark information of a reserved subframe exists between a retransmission and an initial transmitted physical subframe when the PSSCH retransmission of 1 bit is enabled, if the bit of the indication mark information is 0: and if the value is 1, the reserved subframe exists. When PSSCH retransmission is not enabled, the indication mark information is invalid, and the bit value is set to 0.

Further, the synchronization control indication information may further include: 2 bits of synchronization level information, wherein the bits of the synchronization level information correspond to three values, and the meanings are respectively as follows: the value is 01: indicating that the first V2X device is synchronized with the GNSS with a synchronization level of 2; the value is 10: indicating that the first V2X device is synchronized with a (third) V2X device whose synchronization level bit takes a value of 01, the synchronization level being 3; the value is 11: indicating synchronization with a (fourth) V2X device with a synchronization level bit value of 10 or 11, the synchronization level being 4.

4) The PSCCH channel and the PSCCH channel that carry the synchronization control signaling are collectively referred to as a quasi-synchronization signal (i.e., information carried by the PSCCH and the PSCCH is collectively referred to as quasi-synchronization information). The PSBCH sends a synchronization signal, which carries a radio frame number and a subframe number.

5) In order to reduce the transmission delay of the service data, the PSBCH channel and the SLSS signal can be placed in the reserved subframe for transmission, and no special synchronous subframe is set.

6) The PSBCH may also carry UTC time (greenwich time), and is not limited herein.

Receiving side

The receiving side synchronization method may specifically be an air interface signal synchronization process, and as shown in fig. 3, the method includes:

step 31: carrying out subframe detection;

step 32: determining whether a GNSS signal (i.e., GNSS information) is detected, if so, proceeding to step 33, otherwise, proceeding to step 36;

step 33: performing time and frequency correction;

step 34: entering a synchronization state, and determining the synchronization level of the system to be 2;

step 35: clearing the out-of-step counter T2 in the synchronous state, and returning to the step 31;

step 36: determining the current state, and if the current state is the synchronous state, entering step 37; if the status is quasi-synchronous status, go to step 38; if the state is the out-of-step state, go to step 39;

step 37: executing a synchronization process in a synchronization state; see fig. 4;

step 38: executing a synchronization process in a quasi-synchronization state; see fig. 5;

step 39: executing a synchronization process in an out-of-step state; see fig. 6.

The synchronization flow in the synchronization state is shown in fig. 4 (assuming that the current synchronization level of the receiving side itself is i), and includes:

step 41: judging whether a synchronization grade k corresponding to the detected signal is better than a synchronization grade i of the local equipment (namely k < i), or whether the synchronization grade i of the local equipment is 4 (namely i = 4); if yes, go to step 42, if no, go to step 45;

step 42: performing time and frequency correction;

step 43: whether a synchronous signal or a quasi-synchronous signal is detected, the state of the local equipment is maintained to be a synchronous state, and when the synchronization level k of opposite-end equipment is superior to the synchronization level i of the local equipment, the synchronization level R of the local equipment is set to be inferior to k by one level, namely R = k +1; r = k +1 if i =4 and k ≠ 4, or R =4 if i = k =4;

step 44: resetting the out-of-step counter T3 in the synchronous state, and entering step 48;

step 45: adding 1 to an out-of-step counter T3 in a synchronous state; entering step 46;

step 46: judging whether T3 exceeds a corresponding threshold Th _ T3, if yes, entering step 47, and if not, entering step 48;

step 47: entering an out-of-step state, and entering a step 48;

and step 48: and returning to the operation of subframe detection.

The synchronization process in the quasi-synchronization state is shown in fig. 5, and includes:

step 51: judging whether the detected signal is a synchronous signal (i.e. synchronous information), if so, entering step 52, otherwise, entering step 55;

step 52: performing time and frequency correction;

step 53: entering a synchronization state, wherein the own synchronization level R = j +1 when the synchronization level j <4 corresponding to the detected signal, and R = j when j =4;

step 54: clearing the out-of-synchronization counter T4 in the synchronization state, and entering step 512;

step 55: judging whether the detected signal is a quasi-synchronous signal; if yes, go to step 56, if no, go to step 59;

step 56: performing time and frequency correction;

and 57: entering a quasi-synchronous state;

step 58: resetting the out-of-step counter T5 in the quasi-synchronization state, and entering step 512;

step 59: adding 1 to an out-of-step counter T5 in a quasi-synchronous state; entering step 510;

step 510: judging whether T5 exceeds a corresponding threshold Th _ T5, if yes, entering step 511, and if not, entering step 512;

step 511: entering an out-of-step state, and entering step 512;

step 512: and returning to the operation of subframe detection.

The synchronization process in the out-of-step state is shown in fig. 6, and includes:

step 61: judging whether the detected signal is a synchronous signal (i.e. synchronous information), if so, entering step 62, otherwise, entering step 65;

step 62: performing time and frequency correction;

and step 63: entering a synchronization state, wherein the own synchronization level R = j +1 when the synchronization level j <4 corresponding to the detected signal, and R = j when j =4;

step 64: clearing the out-of-synchronization counter T6 in the synchronization state, and entering step 610;

step 65: judging whether the detected signal is a quasi-synchronous signal, if so, entering a step 66, and if not, entering a step 69;

and step 66: performing time and frequency correction;

step 67: entering a quasi-synchronous state;

step 68: clearing the out-of-sync counter T7 in the quasi-synchronization state, and entering step 610;

step 69: maintaining the out-of-step state, entering step 610;

step 610: and returning to the operation of subframe detection.

In particular, it relates to:

1. firstly, a V2X device (a first V2X device or a second V2X device) needs to search for GNSS (synchronization level is 1) signals, synchronization signals, and quasi-synchronization signals (i.e., quasi-synchronization information) in each subframe, and defines its own synchronization state and synchronization level according to the search result:

1) Synchronization status and synchronization level is labeled 2: the V2X equipment which searches the GNSS signal and keeps synchronous with the GNSS signal enters a synchronous state, and the synchronous grade is 2;

2) The synchronization state and the synchronization level mark is 3, namely, GNSS signals are not searched, V2X equipment which is sent by V2X equipment with the synchronization level of 2 and keeps synchronization with the synchronization signals (namely, the signals are used for keeping synchronization with the equipment with the synchronization level of 2) is searched, and the synchronization level is 3;

or, the GNSS signal is not searched, the quasi-synchronization information sent by the V2X device with the synchronization level of 2 is searched, and the V2X device is synchronized with the quasi-synchronization information, where the synchronization level is 3;

3) The synchronization state and the synchronization level are marked as 4, namely, no GNSS signal is searched, and the synchronization level of the V2X device which searches the synchronization signal sent by the V2X device with the synchronization level of 3 or 4 and keeps synchronization with the synchronization signal (namely keeps synchronization by the signal) is 4;

or, the GNSS signal is not searched, the quasi-synchronization information sent by the V2X device with the synchronization level of 3 or 4 is searched, and the V2X device performs synchronization with the quasi-synchronization information, where the synchronization level is 4.

4) Out-of-step state: the method comprises the steps that the V2X network is accessed for the first time, and the V2X equipment which does not search GNSS signals enters an out-of-step state.

5) Once receiving the synchronization signal, the V2X device in the quasi-synchronization state directly enters the synchronization state, and when the level of sending the synchronization signal is 2, the synchronization level of the device entering the synchronization state from the quasi-synchronization state is 3, otherwise, the synchronization level is 4.

6) No matter the synchronization level of the V2X device in the synchronization state is 2 or 3, the V2X device may enter the out-of-synchronization state when a synchronization signal of a higher level is not received within a certain time;

when the synchronization level of the V2X device in the synchronization state is 4, the V2X device may enter the out-of-synchronization state when a synchronization signal not lower than the synchronization level (4) of the V2X device is not received within a certain time;

for a V2X device in a quasi-synchronization state, if a quasi-synchronization signal or a synchronization signal sent by another V2X device is not received within a certain time, the V2X device may also enter an out-of-synchronization state.

2. The process of synchronization at the receiving side includes, but is not limited to, coarse timing, fine timing, physical subframe number calibration, time and frequency correction, and comprehensive timing adjustment using each timing quantity. Wherein:

1) Coarse timing

Considering that a signal of quasi-synchronization subframe data transmitted by a V2X system has a certain characteristic (i.e., the data characteristic of the quasi-synchronization information), for example, after continuously transmitting data of 13 symbols, an LTE-V2X system has one symbol as GP (guard interval) to not transmit data, according to this characteristic, a preliminary timing position of a subframe header, which is coarse timing, can be determined by using a time difference between a rising edge and a falling edge.

2) Fine timing

By using the DMRS pilot sent by the pscch in the quasi-synchronization signal, the received pilot data may be correlated in the time domain to obtain a more accurate subframe header timing offset (which is an offset between the current subframe header position and the standard position at the receiving side), and by using the offset, a more accurate subframe header timing position, which is a fine timing, may be obtained.

That is, the sub-frame head timing position is obtained according to the preliminary timing position and the sub-frame head timing offset.

3) Physical subframe number calculation

After detecting and receiving the synchronization data (i.e. synchronization information) sent by the PSBCH channel, a radio frame number n _ dfn and a subframe number n _ sfn may be obtained, and a specific calculation method for determining the current physical subframe number is n _ psfn = n _ dfn × 10+ n \\ sfn, where n _ psfn is the calibrated physical subframe number and ranges from 0 to 10239.

4) Time and frequency correction

In the case where fine timing is obtained, but there is no physical subframe number, the V2X device enters a quasi-synchronous state.

In the case where the physical subframe number is determined and the fine timing is obtained again, the combination of the two can keep the local V2X device synchronized with the V2X device that has entered the synchronized state, thereby also entering the synchronized state.

The method can correct the frequency after the coarse timing or the fine timing of the subframe head is finished, can accurately obtain the specific position of a virtual carrier according to a preset rule for a V2X system with a certain carrier interval and a certain bandwidth, does not bear data on the virtual carrier, has small signal power, calculates the power of all carrier positions, can determine whether the carrier positions deviate or not according to the characteristics of the relative relationship of the power on different carriers, and corrects the frequency according to the deviation.

In the embodiment of the present invention, regarding the transmission of the clock (i.e. the sub-frame) (schematic diagram of clock transmission from right to left), as shown in fig. 7, S in the diagram is a synchronization signal, and M is a synchronization level; the scheme eliminates the influence of propagation delay in time adjustment, and avoids the one-way increase of delay errors.

From the above, the scheme provided by the embodiment of the invention is as follows: by utilizing the synchronous information, accurate timing synchronization and crystal oscillator synchronization can be realized.

The scheme provided by the embodiment of the invention is illustrated below.

Example 1:

it is assumed that the synchronization control indication information has 4 bits in total, wherein the occupied bit of the subframe information (i.e. the first bit) is only 1 bit; the indication mark information of whether the reserved sub-frame exists between the initial retransmission physical sub-frames when PSSCH retransmission is enabled occupies 1 bit, the indication value of the bit is 0 to indicate existence, and 1 to indicate nonexistence. The synchronization level information occupies 2 bits.

Transmitting side

The indicated value of the occupied bit of the subframe information is 1, which indicates that the subframe is a quasi-synchronization signal subframe containing synchronization control signaling.

When PSSCH retransmission is enabled, the indication mark information of whether the reserved subframe exists between the initial retransmission physical subframes occupies 1 bit, the indication value of the bit is 0 to indicate existence, and 1 to indicate nonexistence.

The synchronization level information occupies 2 bits and is filled according to the synchronization level of the transmitting side V2X device.

Receiving side

1) If the state of the receiving side is the out-of-step state, coarse timing is needed firstly, the initial position of the sub-frame header is determined after coarse timing is finished, and the equipment enters a quasi-synchronization state. The coarse timing procedure is shown in example 4.

2) After the coarse timing is successful, the preparation work of fine timing can be carried out; if the state of the receiving side is quasi-synchronous or synchronous, the preparation work of fine timing can be directly performed over the coarse timing:

firstly, PSCCH detection and decoding are carried out;

obtaining 1-bit subframe information after the decoding is correct, indicating mark information of whether a reserved subframe exists between initial retransmission and 2-bit synchronization grade information when the PSCCH retransmission of 1 bit is enabled; the receiving side can re-determine its own synchronization level according to the synchronization level conversion rule.

3) Fine timing is performed, the fine timing process is shown in example 4.

When the indicated value of the bit occupied by the subframe information is 1, blind detection can be performed on mod (n, 10) according to the signaling content, n is a logical subframe number (obtained according to the bit of the subframe information), and the blind detection range (predefined) is 0-9. The main effect of the different mod (n, 10) values is the local pilot values of the pscch channel calculated by the receiving side. The correct local pilot frequency can ensure that the PSSCH channel of the receiving side is successfully detected and correctly decoded to obtain the fine timing.

4) When the indicated value of the bit occupied by the subframe information is 0, it indicates that the current subframe does not carry the synchronization control signaling, and the receiving side receives the subframe (including the PSCCH and the pscsch) as normal service data.

5) In the quasi-synchronization state, accurate physical subframe numbers cannot be acquired, a synchronization signal (PSBCH) needs to be waited for to be received, and in the process, the quasi-synchronization signal is received at any time, so that the precision of fine timing is kept.

6) After receiving the synchronous signal, calculating a physical subframe number, calibrating a local subframe number, entering a synchronous state by the equipment, and determining the own synchronous level according to the synchronous level information of the equipment at the sending side carried in the synchronous signal; and time and frequency calibration is performed.

Example 2

It is assumed that the synchronization control indication information has 5 bits in total, wherein the occupied bit of the subframe information (i.e. the first bit) has 2 bits; the indication mark information of whether the reserved sub-frame exists between the initial retransmission physical sub-frames when PSSCH retransmission is enabled occupies 1 bit, the indication value of the bit is 0 to indicate existence, and 1 to indicate nonexistence. The synchronization level information occupies 2 bits.

Transmitting side

In the synchronization control indication information, when subframe information is indicated with 2 bits, logical subframes may be divided into any three groups:

a first group, for a subframe with a logical subframe number of n and mod (n, 10) <3, a transmitting side fills an indication value of a subframe information occupied bit in synchronization control indication information in a PSCCH to 1;

in the second group, for a subframe with a logical subframe number of n and mod (n, 10) epsilon {3,4,5}, a transmitting side fills an indication value of a subframe information occupied bit in synchronous control indication information in a PSCCH into 2;

in the third group, for the subframe with the logical subframe number n and mod (n, 10) epsilon {6,7,8,9}, the sending side fills the indicated value of the occupied bit of the subframe information in the synchronous control indication information in the PSCCH to 3;

the indication mark information of whether the reserved sub-frame exists between the primary retransmission physical sub-frames when PSSCH retransmission is enabled in the synchronization control indication information occupies 1 bit, the indication value of the bit is 0 to indicate existence, and the indication value of the bit is 1 to indicate nonexistence.

The synchronization level information of the synchronization control indication information occupies 2 bits and is filled according to the synchronization level of the transmitting side V2X device.

Receiving side

The specific steps are the same as example 1, and the detailed timing is slightly different:

after the synchronization control indication information of the PSCCH is successfully analyzed and 2-bit subframe information is obtained, the value range of mod (n, 10) can be determined according to the indicated value of the bit occupied by the subframe information, for example, when the indicated value of the bit occupied by the subframe information is 1, mod (n, 10) belongs to {0,1,2}, and each value in the set can be subjected to blind detection after the value range set of mod (n, 10) is determined, so that correct receiving and decoding of the PSSCH channel are realized, and fine timing is completed.

When the indicated value of the bit occupied by the subframe information is 0, it indicates that the current subframe does not carry the synchronization control signaling, and the receiving side receives the subframe (including the PSCCH and the pscsch) as normal service data.

Example 3:

assuming that the synchronization control indication information has 7 bits in total, wherein the occupied bit of the subframe information (i.e. the first bit) has 4 bits; the indication mark information of whether the reserved sub-frame exists between the initial retransmission physical sub-frames when PSSCH retransmission is enabled occupies 1 bit, the indication value of the bit is 0 to indicate existence, and 1 to indicate nonexistence. The synchronization level information occupies 2 bits.

Transmitting side

In the synchronization control indication information, when subframe information is indicated with 4 bits, logical subframes may be divided into ten groups:

a first group, for a subframe with a logical subframe number of n and mod (n, 10) =0, a transmitting side fills an indication value of a subframe information occupied bit in synchronization control indication information in a PSCCH to 1;

a second group, for a subframe with a logical subframe number of n and mod (n, 10) =1, a transmitting side fills an indication value of a subframe information occupied bit in synchronization control indication information in a PSCCH to 2;

···

in the tenth group, for a subframe having a logical subframe number of n and mod (n, 10) =9, the transmitting side fills an indication value of a subframe information occupied bit in synchronization control indication information in the PSCCH to 10.

Receiving side

after the synchronization control indication information of the PSCCH channel is successfully analyzed and 4-bit subframe information is obtained, the value range of mod (n, 10) can be determined according to the indication value of the bit occupied by the subframe information, for example, when the indication value of the bit occupied by the subframe information is a value a which is greater than or equal to 1, mod (n, 10) = a-1, and the local pilot frequency required for detecting the PSCCH channel can be correctly generated according to the specific value of mod (n, 10), so that the PSCCH channel can be correctly received and correctly decoded, and fine timing is completed.

Example 4:

coarse timing

1) There is a characteristic regarding the transmission of data in the logical subframe of LTE-V2X that after 13 symbols of data are continuously transmitted, there is one symbol as GP (guard interval) for not transmitting data, and the time domain power is as shown in fig. 8 (the time difference between the rising edge and the falling edge is 13 symbols):

when the V2X device a has data transmitted in one subframe and the received power of the V2X device B is significantly higher than the background noise, a rising power edge and a falling power edge can be always captured, and the time difference between the rising edge and the falling edge is approximately 13 symbols in time.

The Coarse synchronization position TA _ Coarse can be obtained by using the data feature shown in fig. 8.

2) Coarse timing for NR (new air interface) -V2X systems is similar to LTE-V2X systems. Data transmission of a logical subframe of the NR-V2X system has a feature that, after data of 13 symbols is continuously transmitted in a subframe where there is no PSFCH (physical edge link feedback channel) channel (feedback channel carrying ACK (acknowledgement) or NACK (negative acknowledgement) NACK signaling) transmission, there is one symbol as a GP which does not transmit data. In a subframe where the PSFCH channel is transmitted, the transmission of the PSFCH channel is performed on one or two symbols before the GP symbol, and there is also a symbol before the transmission of the PSFCH channel where no data is transmitted as a transition interval between the PSSCH channel and the PSSCH channel. The period for which a regular subframe transmits a PSFCH channel in an NR-V2X system is configurable, typically 2. I.e. only one of every two regular subframes will transmit the PSFCH channel.

When the V2X device a has data transmission of a subframe without a feedback channel, and the received power of the V2X device B is significantly higher than the background noise, a power rising edge and a power falling edge can always be captured, and the time difference between the rising edge and the falling edge is approximately 13 symbols in time length.

The Coarse synchronization position TA _ Coarse can also be obtained using the above data feature.

Fine timing

After the V2X equipment at the receiving side completes coarse timing, the PSCCH channel can be detected; and judging whether the channel carries the synchronous control signaling or not based on the indicated value a of the subframe information occupied bit of the PSCCH. If a is equal to 0, indicating that no synchronous control signaling exists; otherwise, taking a-1 as a result of taking the modulus of the current subframe logical subframe number to 10 (when the subframe information is 4 bits), or a result of taking the modulus of the blind test logical subframe number to 10 (when the subframe information is 1 bit), or a result of taking the modulus of the semi-blind test logical subframe number to 10 (when the subframe information is 2 or 3 bits); and further decoding the PSSCH indicated by the result obtained after the modulus of 10 is performed based on the obtained logical subframe number and other information of the PSCCH. If decoding is successful, a PSSCH-based pilot channel (a pilot signal and a demodulation reference signal (DMRS)) can be estimated to obtain a more accurate subframe start position (a subframe head timing position). This is fine timing.

The starting positions of the sub-frames obtained by the coarse timing and the fine timing are relatively accurate, and the process of determining the starting position of the sub-frame head is timing calibration.

Example 5:

the calculation method of the crystal oscillator adjustment amount comprises the following steps:

and calculating the crystal oscillator adjustment quantity according to the value of the sub-frame head timing offset obtained in the fine timing process and the count value of the crystal oscillator adjustment counter.

From the above, the scheme provided by the embodiment of the invention is as follows:

(1) Under the condition of not needing extra time-frequency resource overhead, the problem of synchronization between the V2X equipment of the GNSS coverage blind area is solved, and the service time delay is reduced.

(2) The design is simple, and the realization is easy.

(3) Timing adjustment and crystal oscillator synchronization are carried out simultaneously, and two synchronization problems are solved.

(4) The timing precision is high, and the crystal oscillator adjustment amount is accurate.

(5) Effectively reducing the service delay.

The embodiment of the present invention further provides a V2X device for an internet of vehicles, where the V2X device is a first V2X device, and the first V2X device includes a road side unit RSU or a vehicle-mounted unit OBU, as shown in fig. 9, and further includes a memory 91, a processor 92, a transceiver 93, and a computer program 94 stored in the memory 91 and operable on the processor 92; the processor 92, when executing the program, performs the following steps:

The V2X device provided in the embodiment of the present invention sends a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device when the first V2X device is in a synchronization state; the preset channel comprises a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the second V2X equipment on the receiving side can be supported to directly and effectively realize synchronization between the V2X equipment according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment in a GNSS signal coverage blind area is solved, the occurrence of desynchronization phenomenon can be avoided, traffic safety is maintained, meanwhile, the scheme that the V2X equipment utilizes the GNSS signal to carry out synchronization is more complete, communication (synchronization) between the V2X equipment can be ensured to be normally carried out in any scene, and therefore potential traffic safety hazards are reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indication value is a non-zero value; or, the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of mod (n, 10) are divided into m groups, one indication value corresponds to a group of possible values of mod (n, 10), m <10; the indication value is a non-zero value; and when the indicated value is a nonzero value, indicating that the PSCCH carries the synchronous control signaling.

Further, the bit rate of the information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

Further, the synchronization control indication information further includes: 1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission and the initial transmitted physical subframe when the PSSCH retransmission is enabled.

Further, the processor is further configured to: before transmitting a bypass broadcast channel PSBCH and/or a preset channel to the second V2X device, searching Global Navigation Satellite System (GNSS) information, synchronization information and quasi-synchronization information in each subframe; and under the condition that the first V2X device is in a synchronous state, determining the synchronous level of the first V2X device according to a search result.

Specifically, the processor is specifically configured to: determining that the synchronization level of the first V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a fifth V2X device with a synchronization level of 2 is searched, and synchronization with the fifth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a sixth V2X device with a synchronization level of 3 or 4 is searched, and synchronization with the sixth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 4.

In the embodiment of the invention, the PSBCH also carries Greenwich UTC time.

The implementation embodiments of the synchronization method on the first V2X device side are all applicable to the embodiment of the V2X device, and the same technical effect can be achieved.

The embodiment of the present invention further provides a V2X device for a vehicle networking, where the V2X device is a second V2X device, and the second V2X device includes a road side unit RSU or a vehicle mounted unit OBU, as shown in fig. 10, and further includes a memory 101, a processor 102, a transceiver 103, and a computer program 104 stored in the memory 101 and capable of running on the processor 102; the processor 102, when executing the program, implements the steps of:

carrying out synchronization according to the PSBCH and/or a preset channel;

The V2X device provided in the embodiment of the present invention receives a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device; carrying out synchronization according to the PSBCH and/or a preset channel; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logic subframe, and the logic subframe is a subframe except the reserved subframe; the synchronization between the V2X equipment can be effectively realized directly according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment with a GNSS signal covering blind area is solved, the occurrence of desynchronizing phenomenon can be avoided, the traffic safety is maintained, meanwhile, the scheme that the V2X equipment performs synchronization by utilizing the GNSS signal is more complete, the communication (synchronization) between the V2X equipment can be normally performed in any scene, and thus the traffic safety hidden danger is reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indication value is a non-zero value; or, the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of mod (n, 10) are divided into m groups, one indication value corresponds to a group of possible values of mod (n, 10), m <10; the indicated value is a non-zero value; and when the indicated value is a non-zero value, indicating that the PSCCH carries the synchronous control signaling.

Wherein the PSBCH further carries the synchronization level of the first V2X device.

Specifically, the processor is specifically configured to: under the condition that the second V2X equipment is in an out-of-step state or a quasi-synchronization state, synchronizing according to the PSBCH and/or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel.

Further, the processor is further configured to: searching Global Navigation Satellite System (GNSS) information, synchronization information and quasi-synchronization information in each subframe before synchronization is carried out according to the PSBCH and/or a preset channel when the second V2X equipment is in a synchronization state or a quasi-synchronization state; and under the condition that the second V2X device is in a synchronous state, determining the synchronization level of the second V2X device according to the search result.

Specifically, the processor is specifically configured to: determining that the synchronization level of the second V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a seventh V2X device with a synchronization level of 2 is searched, and synchronization with the seventh V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by an eighth V2X device having a synchronization level of 3 or 4 is searched, and synchronization with the eighth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 4.

Wherein the processor is specifically configured to: detecting the PSCCH according to the initial timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information; determining a value of mod (n, 10) from the indication value of the first bit; obtaining a local pilot frequency numerical value of the PSSCH according to the synchronous control signaling, the CRC check bit information and the mod (n, 10) value; detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining a subframe head timing offset according to a pilot signal of the PSSCH and a demodulation reference signal (DMRS) after the decoding is successful; and obtaining the timing position of the subframe head according to the preliminary timing position and the timing offset of the subframe head, and entering a quasi-synchronization state.

In an embodiment of the present invention, the processor is specifically configured to: blind-detecting all possible values of the mod (n, 10) under the condition that the number of bits of the first bit is 1 and the indication value of the first bit is 1, and obtaining a unique mod (n, 10) value after the blind-detection is successful; or, in the case that the number of bits of the first bit is 4 and the indication value of the first bit is a non-zero value, subtracting 1 from the indication value to obtain the value of mod (n, 10); or, when the number of bits of the first bit is 2 or 3 and the indication value of the first bit is a non-zero value, determining possible values of the mod (n, 10) of the corresponding group according to the indication value, performing blind detection on each possible value of the mod (n, 10), and obtaining a unique mod (n, 10) value after the blind detection is successful.

Further, the processor is further configured to: before the PSCCH is detected according to the preliminary timing position of the subframe header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information, when the second V2X equipment is in an out-of-step state, the preliminary timing position is obtained according to the data characteristics of the quasi-synchronous information, and the out-of-step state enters a quasi-synchronous state; or, when the second V2X device is in a synchronous state or a quasi-synchronous state, acquiring and storing the preliminary timing position.

Wherein the synchronization information comprises a radio frame number and a subframe number; the processor is specifically configured to: obtaining a physical subframe number of the second V2X device according to the radio frame number and the subframe number; and correcting time and frequency according to the timing position of the subframe head and the physical subframe number, keeping synchronization with the first V2X device, and entering a synchronization state.

In this embodiment of the present invention, the synchronization control indication information further includes: 1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission enabled by PSSCH retransmission and the initial transmitted physical subframe.

Specifically, the processor is specifically configured to: if the PSSCH decoding is successful but the PSSCH decoding is failed, obtaining a physical subframe interval between the first transmission and the retransmission of the PSSCH based on a logical subframe interval between the first transmission and the retransmission of the PSSCH indicated by the PSCCH and the indication mark information, and carrying out combined decoding on the PSSCH according to the physical subframe interval.

Further, the processor is further configured to: obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of a crystal oscillator adjustment counter; and carrying out crystal oscillator synchronization according to the crystal oscillator adjustment amount.

In an embodiment of the present invention, the processor is further configured to: determining a synchronization level of the second V2X device according to a synchronization level of the first V2X device carried by the PSBCH under the condition that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel.

Wherein, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the processor is specifically configured to: determining that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the first V2X device is the lowest synchronization level; or, in a case that the synchronization level of the first V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the processor is specifically configured to: determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, the synchronization level of the second V2X device is a lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the processor is specifically configured to: determining that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the second V2X device is the lowest synchronization level; or, in a case that the synchronization level of the second V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Further, the processor is further configured to: before receiving a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device, when a second V2X device is in a synchronous state, the synchronous grade of the second V2X device is not the lowest synchronous grade, and the PSBCH and/or the preset channel sent by a ninth V2X device are not received in a preset time period, entering an out-of-synchronization state; the ninth V2X device has a higher synchronization level than the second V2X device; or, when the second V2X device is in a synchronization state and the synchronization level of the second V2X device is the lowest synchronization level and does not receive the PSBCH and/or the preset channel sent by the tenth V2X device within the preset time period, entering an out-of-synchronization state; the synchronization level of the tenth V2X device is not lower than the synchronization level of the second V2X device; or, entering an out-of-synchronization state when the second V2X device is in a quasi-synchronization state and does not receive the PSBCH and/or the preset channel sent by the eleventh V2X device within a preset time period.

In the embodiment of the invention, the PSBCH also carries greenwich UTC time.

The implementation embodiments of the synchronization method on the second V2X device side are all applicable to the embodiment of the V2X device, and the same technical effect can be achieved.

the program realizes the steps of the synchronization method on the second V2X device side described above when executed by a processor.

The implementation embodiments of the synchronization method of the first V2X device side or the second V2X device side are all applicable to the embodiment of the computer-readable storage medium, and the same technical effects can be achieved.

An embodiment of the present invention further provides a synchronization apparatus, which is applied to a first vehicle networking V2X device, where the first V2X device includes a road side unit RSU or a vehicle mounted unit OBU, as shown in fig. 11, and the synchronization apparatus includes:

a first sending module 111, configured to send a bypass broadcast channel PSBCH and/or a preset channel to a second V2X device when the first V2X device is in a synchronization state;

The synchronization device provided by the embodiment of the invention is applied to a first vehicle networking V2X device, the first V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method sends a bypass broadcast channel (PSBCH) and/or a preset channel to a second V2X device under the condition that the first V2X device is in a synchronization state; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the second V2X equipment on the receiving side can be supported to directly and effectively realize synchronization between the V2X equipment according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment in a GNSS signal coverage blind area is solved, the occurrence of desynchronization phenomenon can be avoided, traffic safety is maintained, meanwhile, the scheme that the V2X equipment utilizes the GNSS signal to carry out synchronization is more complete, communication (synchronization) between the V2X equipment can be ensured to be normally carried out in any scene, and therefore potential traffic safety hazards are reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of the mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each indication value corresponds to the sum of all possible values of mod (n, 10) plus 1 in a one-to-one manner; the indication value is a non-zero value; or the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of the mod (n, 10) are divided into m groups, one of the indication values corresponds to a group of possible values of the mod (n, 10), m <10; the indication value is a non-zero value; and when the indicated value is a non-zero value, indicating that the PSCCH carries the synchronous control signaling.

Further, the synchronization apparatus further includes: a first searching module, configured to search for global navigation satellite system GNSS information, synchronization information, and quasi-synchronization information at each subframe before transmitting a bypass broadcast channel PSBCH and/or a preset channel to the second V2X device; a first determining module, configured to determine, according to a search result, a synchronization level of the first V2X device when the first V2X device is in a synchronization state.

Specifically, the first determining module includes: the first determining submodule is used for determining that the synchronization level of the first V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a fifth V2X device with a synchronization level of 2 is searched, and synchronization with the fifth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a sixth V2X device with a synchronization level of 3 or 4 is searched, and synchronization with the sixth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 4.

In the embodiment of the invention, the PSBCH also carries Greenwich UTC time.

The implementation embodiments of the synchronization method on the first V2X device side are all applicable to the embodiment of the synchronization apparatus, and the same technical effects can be achieved.

An embodiment of the present invention further provides a synchronization apparatus, which is applied to a second vehicle networking V2X device, where the second V2X device includes a road side unit RSU or an on board unit OBU, as shown in fig. 12, the synchronization apparatus includes:

a first receiving module 121, configured to receive a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device;

a first synchronization module 122, configured to perform synchronization according to the PSBCH and/or a preset channel;

the preset channel comprises a bypass control channel PSCCH and a bypass shared channel PSSCH;

The synchronization device provided by the embodiment of the invention is applied to a second vehicle networking V2X device, the second V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method receives a bypass broadcast channel (PSBCH) and/or a preset channel sent by a first V2X device; carrying out synchronization according to the PSBCH and/or a preset channel; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH; the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe; the synchronization between the V2X equipment can be effectively realized directly according to the PSBCH and/or the preset channel, the synchronization problem of the V2X equipment covering a blind area by the GNSS signal is solved, the occurrence of desynchronization can be avoided, the traffic safety is maintained, meanwhile, the scheme for synchronizing the V2X equipment by the GNSS signal is more complete, the communication (synchronization) between the V2X equipment can be normally carried out in any scene, and the traffic safety hidden danger is reduced; moreover, a special synchronous subframe is not required to be set, so that the resource overhead can be reduced, the timely and accurate transmission of service data is ensured, and the transmission delay of the service is reduced; in addition, the scheme is easy to realize and has high synchronization precision; the problems that in the prior art, the transmission delay of the service is increased and the synchronization cannot be realized in the synchronization scheme are solved well.

Wherein the synchronization control indication information includes: subframe information of a first bit, where the first bit is greater than or equal to 1 bit and less than or equal to 4 bits, and the subframe information is used to indicate whether the PSCCH carries synchronization control signaling and a result mod (n, 10) obtained by modulo 10 a logical subframe number n of the PSCCH; wherein the number of bits of the first bit is 1 and the indicator value of the first bit is 1, the indicator value corresponding to all possible values of mod (n, 10); or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indication value is a non-zero value; or, the number of bits of the first bit is 2 or 3, the indication value of the first bit has m, all possible values of mod (n, 10) are divided into m groups, one indication value corresponds to a group of possible values of mod (n, 10), m <10; the indication value is a non-zero value; and when the indicated value is a nonzero value, indicating that the PSCCH carries the synchronous control signaling.

Specifically, the first synchronization module includes: a first synchronization sub-module, configured to perform synchronization according to the PSBCH and/or a preset channel when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel; or, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, performing synchronization according to the PSBCH and/or a preset channel.

Further, the synchronization apparatus further includes: a second searching module, configured to search for GNSS information, synchronization information, and quasi-synchronization information of a global navigation satellite system in each subframe before performing synchronization according to the PSBCH and/or a preset channel when the second V2X device is in a synchronization state or a quasi-synchronization state; a second determining module, configured to determine, according to a search result, a synchronization level of the second V2X device when the second V2X device is in a synchronization state.

Specifically, the second determining module includes: the second determining submodule is used for determining that the synchronization level of the second V2X device is 2 under the condition that the search result is that GNSS information is searched and the GNSS synchronization is kept according to the GNSS information; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a seventh V2X device with a synchronization level of 2 is searched, and synchronization with the seventh V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 3; or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by an eighth V2X device having a synchronization level of 3 or 4 is searched, and synchronization with the eighth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the second V2X device is 4.

Wherein the first synchronization module comprises: the first processing sub-module is used for detecting the PSCCH according to the preliminary timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information; a second processing submodule for determining a value of mod (n, 10) from an indication of the first bit; a third processing sub-module, configured to obtain a local pilot value of the PSSCH according to the synchronization control signaling, CRC check bit information, and a mod (n, 10) value; the fourth processing sub-module is used for detecting and decoding the PSSCH according to the local pilot frequency value, and obtaining the timing offset of a subframe head according to the pilot signal of the PSSCH and the DMRS (demodulation reference signal) after the decoding is successful; and the fifth processing submodule is used for obtaining the timing position of the sub-frame header according to the preliminary timing position and the timing offset of the sub-frame header and entering a quasi-synchronization state.

In this embodiment of the present invention, the second processing sub-module includes: a first processing unit, configured to blind-detect all possible values of the mod (n, 10) when the number of bits of the first bit is 1 and an indication value of the first bit is 1, and obtain a unique mod (n, 10) value after the blind detection is successful; or, when the number of bits of the first bit is 4 and the indication value of the first bit is a non-zero value, subtracting 1 from the indication value to obtain the value of mod (n, 10); or, when the number of bits of the first bit is 2 or 3 and the indication value of the first bit is a non-zero value, determining possible values of mod (n, 10) of the corresponding group according to the indication value, performing blind detection on each possible value of mod (n, 10), and obtaining a unique mod (n, 10) value after the blind detection is successful.

Further, the synchronization apparatus further includes: a first processing module, configured to, before detecting the PSCCH according to a preliminary timing position of a subframe header to obtain the synchronization control signaling and cyclic redundancy check CRC check bit information, obtain the preliminary timing position according to data characteristics of the quasi-synchronization information when the second V2X device is in an out-of-synchronization state, and enter a quasi-synchronization state from the out-of-synchronization state; or, when the second V2X device is in a synchronous state or a quasi-synchronous state, acquiring and storing the preliminary timing position.

Wherein the synchronization information comprises a radio frame number and a subframe number; the first synchronization module includes: a sixth processing submodule, configured to obtain a physical subframe number of the second V2X device according to the radio frame number and the subframe number; and the seventh processing submodule is used for correcting time and frequency according to the timing position of the subframe head and the physical subframe number, keeping synchronization with the first V2X device and entering a synchronization state.

In this embodiment of the present invention, the synchronization control indication information further includes: 1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission and the initial transmitted physical subframe when the PSSCH retransmission is enabled.

Specifically, the fourth processing sub-module includes: and the second processing unit is used for obtaining a physical subframe interval between the first transmission and the retransmission of the PSSCH based on the logical subframe interval between the first transmission and the retransmission of the PSSCH indicated by the PSCCH and the indication mark information if the PSSCH is successfully decoded but the PSSCH is unsuccessfully decoded, and performing combined decoding of the PSSCH according to the physical subframe interval.

Further, the first synchronization module further includes: the eighth processing submodule is used for obtaining crystal oscillator adjustment quantity according to the subframe header timing offset and the count value of the crystal oscillator adjustment counter; and the ninth processing submodule is used for carrying out crystal oscillator synchronization according to the crystal oscillator adjustment quantity.

In this embodiment of the present invention, the first synchronization module further includes: a third determining submodule, configured to determine, when the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, a synchronization level of the second V2X device according to a synchronization level of the first V2X device carried by the PSBCH; or, a fourth determining sub-module, configured to, when the second V2X device is in a synchronization state, and a synchronization level of the second V2X device is not a lowest synchronization level, and a synchronization level of the first V2X device is higher than a synchronization level of the second V2X device, re-determine the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel; or, a fifth determining sub-module, configured to re-determine the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or the preset channel when the second V2X device is in the synchronization state, the synchronization level of the second V2X device is the lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device.

Wherein, under the condition that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the third determining sub-module includes: a first determining unit, configured to determine that the synchronization level of the second V2X device is a lowest synchronization level when the synchronization level of the first V2X device is the lowest synchronization level; or, in a case that the synchronization level of the first V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the fourth determining submodule includes: a second determination unit for determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Wherein, when the second V2X device is in a synchronization state, and the synchronization level of the second V2X device is a lowest synchronization level, and the synchronization level of the first V2X device is not lower than the synchronization level of the second V2X device, the fifth determining sub-module includes: a third determining unit, configured to determine that the synchronization level of the second V2X device is the lowest synchronization level when the synchronization level of the second V2X device is the lowest synchronization level; or, in a case that the synchronization level of the second V2X device is not the lowest synchronization level, determining that the synchronization level of the second V2X device is lower than the synchronization level of the first V2X device by a first level.

Further, the synchronization apparatus further includes: a second processing module, configured to, before receiving a PSBCH and/or a preset channel that is a bypass broadcast channel and is sent by a first V2X device, enter an out-of-sync state when the second V2X device is in a synchronization state, and a synchronization level of the second V2X device is not a lowest synchronization level, and a PSBCH and/or the preset channel that is sent by a ninth V2X device is not received within a preset time period; the ninth V2X device has a higher synchronization level than the second V2X device; or, when the second V2X device is in a synchronization state and the synchronization level of the second V2X device is the lowest synchronization level and does not receive the PSBCH and/or the preset channel sent by the tenth V2X device within the preset time period, entering an out-of-synchronization state; the synchronization level of the tenth V2X device is not lower than the synchronization level of the second V2X device; or, entering an out-of-synchronization state when the second V2X device is in a quasi-synchronization state and does not receive the PSBCH and/or the preset channel sent by the eleventh V2X device within a preset time period.

In the embodiment of the invention, the PSBCH also carries greenwich UTC time.

The implementation embodiments of the synchronization method on the second V2X device side are all applicable to the embodiment of the synchronization apparatus, and the same technical effects can be achieved.

It should be noted that many of the functional components described in this specification are referred to as modules/sub-modules/units in order to more particularly emphasize their implementation independence.

In embodiments of the present invention, the modules/sub-modules/units may be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions which may, for instance, be constructed as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different bits which, when joined logically together, comprise the module and achieve the stated purpose for the module.

Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.

When a module can be implemented by software, considering the level of existing hardware technology, a module implemented by software may build a corresponding hardware circuit to implement a corresponding function, without considering cost, and the hardware circuit may include a conventional Very Large Scale Integration (VLSI) circuit or a gate array and an existing semiconductor such as a logic chip, a transistor, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A synchronization method is applied to a first vehicle networking (V2X) device, wherein the first V2X device comprises a Road Side Unit (RSU) or a vehicle-mounted unit (OBU), and the synchronization method comprises the following steps:

the PSBCH carries synchronization information, and a sending subframe of the PSBCH is a reserved subframe; the preset channels comprise a bypass control channel PSCCH and a bypass shared channel PSSCH;

the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logical subframe, and the logical subframe is a subframe except the reserved subframe;

the synchronization control indication information includes:

or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each of the indication values corresponds to the sum of all possible values of mod (n, 10) plus 1, respectively; the indicated value is a non-zero value;

2. The synchronization method according to claim 1, wherein the synchronization control indication information further comprises: 2 bits of synchronization level information, wherein bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

3. The synchronization method according to claim 1 or 2, wherein the synchronization control indication information further comprises:

1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission and an initial transmission physical subframe when PSSCH retransmission is enabled; bits of the indicator flag information: if the value is 0, the fact that a reserved subframe does not exist between the retransmission and the initial transmission physical subframe when the PSSCH is enabled is represented; and if the value is 1, indicating that a reserved subframe exists between the retransmission and the initial transmitted physical subframe when the PSSCH retransmission is enabled.

4. The synchronization method of claim 3, wherein the indication flag information is invalid when the PSSCH retransmission is not enabled, and wherein a bit indication value of the indication flag information is 0.

5. The synchronization method according to claim 1, wherein the PSBCH further carries a synchronization level of the first V2X device.

6. The synchronization method according to any one of claims 1 to 2, wherein the information carried by the PSCCH and PSCCH is collectively referred to as quasi-synchronization information.

7. The synchronization method according to claim 6, characterized in that before transmitting a bypass broadcast channel PSBCH and/or a preset channel to the second V2X device, further comprising:

8. The synchronization method according to claim 7, wherein the determining the synchronization level of the first V2X device according to the search result comprises:

or, when the search result indicates that GNSS information is not searched but synchronization information or quasi-synchronization information sent by a sixth V2X device having a synchronization level of 3 or 4 is searched, and synchronization with the sixth V2X device is maintained according to the synchronization information or synchronization is performed according to the quasi-synchronization information, determining that the synchronization level of the first V2X device is 4.

9. The synchronization method according to claim 1, wherein the PSBCH further carries greenwich UTC time.

10. A synchronization method is applied to a second vehicle networking (V2X) device, the second V2X device comprises a Road Side Unit (RSU) or an On Board Unit (OBU), and the synchronization method comprises the following steps:

carrying out synchronization according to the PSBCH and/or a preset channel;

the PSCCH carries synchronization control indication information, a sending subframe of the PSCCH is a logic subframe, and the logic subframe is a subframe except the reserved subframe;

the synchronization control indication information includes:

11. The synchronization method according to claim 10, wherein the synchronization control indication information further comprises: 2 bits of synchronization level information, wherein the bits of the synchronization level information: if the value is 01, the first V2X device is synchronous with a Global Navigation Satellite System (GNSS), and the synchronization level is 2; if the value is 10, it indicates that the first V2X device is synchronized with a third V2X device whose bit value of the synchronization level information is 01, and the synchronization level is 3; if the value is 11, it indicates that the first V2X device is synchronized with a fourth V2X device whose bit of the synchronization level information takes a value of 10 or 11, and the synchronization level is 4.

12. The synchronization method according to claim 11, wherein the PSBCH further carries a synchronization level of the first V2X device.

13. The synchronization method according to claim 12, wherein the performing synchronization according to the PSBCH and/or a preset channel comprises:

14. The synchronization method according to any one of claims 11 to 13, wherein the information carried by the PSCCH and PSCCH is collectively referred to as quasi-synchronization information.

15. The synchronization method according to claim 14, wherein before performing synchronization according to the PSBCH and/or a preset channel when the second V2X device is in a synchronization state or a quasi-synchronization state, further comprising:

16. The synchronization method according to claim 15, wherein the determining the synchronization level of the second V2X device according to the search result comprises:

17. The synchronization method according to claim 14, wherein the performing synchronization according to the preset channel comprises:

detecting the PSCCH according to the initial timing position of the sub-frame header to obtain the synchronous control signaling and Cyclic Redundancy Check (CRC) check bit information;

18. The synchronization method of claim 17, wherein determining a value of mod (n, 10) based on the indicator value of the first bit comprises:

19. The synchronization method according to claim 17, wherein before detecting the PSCCH according to a preliminary timing position of a subframe header to obtain the synchronization control signaling and CRC check bit information, further comprising:

20. The synchronization method of claim 17, wherein the synchronization information comprises a radio frame number and a subframe number; according to the PSBCH, carrying out synchronization, comprising:

21. The synchronization method according to claim 17, wherein the synchronization control indication information further comprises:

1 bit of indication mark information, wherein the indication mark information is used for indicating whether a reserved subframe exists between a retransmission physical subframe and an initial transmission physical subframe when the PSSCH is enabled for retransmission; bits of the indicator flag information: if the value is 0, indicating that no reserved subframe exists between the retransmission and the initial transmission physical subframe when PSSCH retransmission is enabled; and if the value is 1, indicating that a reserved subframe exists between the retransmission enabled by PSSCH retransmission and the initial transmitted physical subframe.

22. The synchronization method of claim 21, wherein the indicator information is invalid when the PSSCH retransmission is not enabled, and wherein a bit indicator of the indicator information is 0.

23. The synchronization method as claimed in claim 21, wherein the detecting and decoding the psch according to the local pilot values comprises:

24. The synchronization method according to claim 15, wherein the synchronization is performed according to the preset channel, further comprising:

obtaining crystal oscillator adjustment quantity according to the timing offset of the subframe header and the count value of the crystal oscillator adjustment counter;

25. The synchronization method according to claim 12, wherein the synchronization is performed according to the PSBCH and/or a preset channel, further comprising:

determining the synchronization grade of the second V2X device according to the synchronization grade of the first V2X device carried by the PSBCH under the condition that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state;

26. The synchronization method according to claim 25, wherein in case that the second V2X device is in an out-of-synchronization state or a quasi-synchronization state, the determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH comprises:

27. The synchronization method of claim 25, wherein in a case that the second V2X device is in a synchronization state, the synchronization level of the second V2X device is not the lowest synchronization level, and the synchronization level of the first V2X device is higher than the synchronization level of the second V2X device, the re-determining the synchronization level of the second V2X device according to the synchronization level of the first V2X device carried by the PSBCH or a preset channel comprises:

28. The synchronization method according to claim 25, wherein in case that the second V2X device is in synchronization state, and the synchronization rank of the second V2X device is the lowest synchronization rank, and the synchronization rank of the first V2X device is not lower than the synchronization rank of the second V2X device, said re-determining the synchronization rank of the second V2X device according to the synchronization rank of the first V2X device carried by the PSBCH or a preset channel comprises:

29. The synchronization method according to claim 10, wherein before receiving the bypass broadcast channel PSBCH and/or the preset channel transmitted by the first V2X device, further comprising:

entering an out-of-sync state when the second V2X device is in a sync state, and the sync level of the second V2X device is not the lowest sync level, and the PSBCH and/or the preset channel sent by the ninth V2X device are not received within a preset time period; the ninth V2X device has a higher synchronization level than the second V2X device;

30. The synchronization method of claim 10, wherein the PSBCH further carries greenwich UTC time.

31. A V2X device for a vehicle networking, the V2X device being a first V2X device, the first V2X device comprising a road side unit, RSU, or an on board unit, OBU, further comprising a memory, a processor, a transceiver, and a computer program stored on the memory and operable on the processor; wherein the processor implements the following steps when executing the program:

the synchronization control indication information includes:

32. A V2X device for a vehicle networking, the V2X device being a second V2X device, the second V2X device comprising a road side unit, RSU, or an on board unit, OBU, further comprising a memory, a processor, a transceiver, and a computer program stored on the memory and operable on the processor; wherein the processor implements the following steps when executing the program:

receiving a bypass broadcast channel PSBCH and/or a preset channel sent by first V2X equipment through the transceiver;

carrying out synchronization according to the PSBCH and/or a preset channel;

the synchronization control indication information includes:

33. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the synchronization method according to any one of claims 1 to 9; alternatively, the first and second electrodes may be,

the program when executed by a processor implementing the steps of the synchronization method according to any one of claims 10 to 30.

34. The utility model provides a synchronizer, is applied to first car networking V2X equipment, first V2X equipment includes road side unit RSU or on-board unit OBU, its characterized in that, synchronizer includes:

the synchronization control indication information includes:

or, the number of bits of the first bit is 4, the indication value of the first bit has 10, and each indication value corresponds to the sum of all possible values of mod (n, 10) plus 1 in a one-to-one manner; the indication value is a non-zero value;

35. A synchronizer is applied to a second vehicle networking V2X device, the second V2X device comprises a Road Side Unit (RSU) or an On Board Unit (OBU), and the synchronizer comprises:

a first receiving module, configured to receive a bypass broadcast channel PSBCH and/or a preset channel sent by a first V2X device; the first synchronization module is used for carrying out synchronization according to the PSBCH and/or a preset channel;

the synchronization control indication information includes: