Internet of vehicles system and time synchronization method and device thereof

Abstract

The application provides a vehicle-to-everything system, a time synchronization method and device thereof. The vehicle-to-everything system comprises a plurality of V2X devices. The time synchronization method comprises the following steps: acquiring a synchronization broadcast signal provided by a first V2X device in a time synchronization state; acquiring a target time offset value; and determining a final precise time synchronized with the first V2X device according to the target time offset value and the synchronization broadcast signal. The application enables a V2X device in an out-of-sync state to acquire accurate time information, ensures that the V2X device is applicable to more scenes, and prevents and reduces the accident rate of the system in a tunnel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a vehicle networking system and a time synchronization method and device thereof. BACKGROUND

[0002] With the rapid development of communication technology, wireless communication technology also has new application scenarios, such as V2X (Vehicle to Everything), and the vehicle-road cooperation scheme based on V2X technology is gradually deployed. In the future, V2X devices will achieve large-area coverage and popularization.

[0003] At present, GNSS (global navigation satellite system) signals are introduced into GNSS non-coverage areas through wired methods or optical fiber connections, or LTE / 5G base stations are deployed for time service, so as to ensure V2X time source synchronization and availability.

[0004] However, the above method has high cost and complicated construction, and for tunnels with a relatively long distance, such as tunnels longer than 5km, the construction difficulty is high, the deployment of time sources has high cost and long cycle, and is not conducive to the large-scale promotion of V2X. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art.

[0006] To this end, one object of the present application is to provide a time synchronization method for a vehicle networking system, which enables V2X devices in a step-out state to obtain accurate time information, ensures uninterrupted communication of V2X devices, guarantees V2X to be applicable to more scenarios, and prevents and reduces the accident rate of the system in tunnels.

[0007] To this end, a second object of the present application is to provide a time synchronization device for a vehicle networking system.

[0008] To this end, a third object of the present application is to provide a vehicle networking system.

[0009] In order to achieve the above-mentioned objects, an embodiment of the first aspect of the present application provides a time synchronization method for a vehicle networking system, comprising: acquiring a synchronization broadcast signal provided by a first V2X device in a time synchronization state; acquiring a target time offset value; and determining a final accurate time synchronized with the first V2X device according to the target time offset value and the synchronization broadcast signal.

[0010] According to the time synchronization method of the Internet of Vehicles system, when the V2X device enters the out-of-sync state, the synchronization broadcast signal and the target time offset value provided by the first V2X device in the time synchronization state are acquired, and the time of the V2X device in the out-of-sync state is calibrated according to the target time offset value, so as to obtain the final accurate time of the V2X device in the out-of-sync state, avoid the high cost and complicated construction caused by optical fiber or wired connection, calibrate the time by acquiring the synchronization broadcast signal provided by the first V2X device, so that the V2X device in the out-of-sync state can obtain accurate time information, so that the V2X device communication is not interrupted, the V2X is ensured to be applicable to more scenes, and the accident rate of the system in the tunnel is prevented and reduced.

[0011] In some embodiments, obtaining the target time offset value comprises: acquiring an initial accurate time by analyzing the synchronization broadcast signal; acquiring a flight time according to the initial accurate time; and acquiring the target time offset value according to the flight time.

[0012] In some embodiments, acquiring the initial accurate time by analyzing the synchronization broadcast signal comprises: acquiring a source time of the synchronization broadcast signal, a demodulation processing time and a frequency offset by analyzing the synchronization broadcast signal; and determining the initial accurate time according to the source time, the demodulation processing time and the frequency offset.

[0013] In some embodiments, acquiring the flight time according to the initial accurate time comprises: continuously receiving the synchronization broadcast signal multiple times; acquiring an initial accurate time corresponding to each time the synchronization broadcast signal is received by analyzing each time the synchronization broadcast signal is received; acquiring a preset receiving interval time of the initial accurate time multiple times in succession; and acquiring the flight time according to the initial accurate time and the preset receiving interval time.

[0014] In some embodiments, acquiring the target time offset value according to the flight time comprises: determining an initial time offset value according to the flight time, the demodulation processing time and the frequency offset; determining a confidence percentage according to the initial time offset value; and taking the initial time offset value as the target time offset value when the confidence percentage is greater than a preset confidence threshold.

[0015] In some embodiments, determining the final accurate time synchronized with the first V2X device according to the target time offset value and the synchronization broadcast signal comprises: determining a source time of receiving the synchronization broadcast signal; and determining the final accurate time synchronized with the V2X device according to the source time and the target time offset value.

[0016] In some embodiments, the acquiring the synchronization broadcast signal provided by the first V2X device in the time synchronization state comprises: establishing a synchronization channel; and acquiring the synchronization broadcast signal provided by the first V2X device in the time synchronization state by using the synchronization channel.

[0017] In some embodiments, before the acquiring the synchronization broadcast signal provided by the first V2X device in the time synchronization state, the method further comprises: determining that the V2X device enters an out-of-sync state, and controlling the V2X device to stop sending the synchronization broadcast signal.

[0018] In some embodiments, the obtaining the target time offset value comprises: acquiring a plurality of standard reference times; determining a plurality of time offset values and a plurality of confidence percentage corresponding to the plurality of time offset values according to the plurality of standard reference times; and determining the target time offset value according to the plurality of time offset values and the plurality of confidence percentage.

[0019] In some embodiments, the determining the target time offset value according to the plurality of time offset values and the plurality of confidence percentage comprises: if at least two of the plurality of confidence percentage are greater than a preset confidence threshold, performing a weighted calculation on the time offset values corresponding to the at least two of the plurality of confidence percentage to obtain the target time offset value; or if one of the plurality of confidence percentage is greater than the preset confidence threshold, taking the time offset value corresponding to the confidence percentage greater than the preset confidence threshold as the target time offset value.

[0020] To achieve the above object, embodiments of the second aspect of the present application propose a time synchronization device of a vehicle-to-everything (V2X) system, the device comprising: a first acquiring module configured to acquire a synchronization broadcast signal provided by a first V2X device in a time synchronization state; a second acquiring module configured to acquire a target time offset value; and a determining module configured to determine a final accurate time synchronized with the first V2X device according to the target time offset value and the synchronization broadcast signal.

[0021] The time synchronization device of the vehicle-to-everything (V2X) system according to the embodiments of the present application, when the V2X device enters an out-of-sync state, acquires a synchronization broadcast signal provided by a first V2X device in a time synchronization state and a target time offset value, and performs time calibration on the V2X device in the out-of-sync state according to the target time offset value to obtain a final accurate time of the V2X device in the out-of-sync state, thereby avoiding high cost and complicated construction caused by optical fiber or wired connection, and enabling the V2X device in the out-of-sync state to obtain accurate time information by time calibration based on the synchronization broadcast signal provided by the first V2X device, so that the V2X device communication is not interrupted, and the V2X is ensured to be applicable to more scenarios, and the accident rate of the system in the tunnel is prevented and reduced.

[0022] To achieve the above object, the embodiment of the third aspect of the present application proposes a vehicle-to-everything system, comprising: a time synchronization device of the vehicle-to-everything system as described in the above embodiment; and a V2X device in communication with the time synchronization device.

[0023] According to the vehicle-to-everything system of the embodiment of the present application, when the V2X device enters the out-of-sync state, the synchronization broadcast signal and the target time offset value provided by the first V2X device in the time synchronization state are acquired, and the V2X device in the out-of-sync state is time calibrated according to the target time offset value, so as to obtain the final accurate time of the V2X device in the out-of-sync state, thereby avoiding the high cost and the complicated construction caused by the optical fiber or the wired connection, and through the time calibration by the synchronization broadcast signal provided by the first V2X device, the V2X device in the out-of-sync state can obtain accurate time information, so that the V2X device communication is not interrupted, the V2X is ensured to be applicable to more scenes, and the accident rate of the system in the tunnel is prevented and reduced.

[0024] In some embodiments, the V2X device comprises a roadside unit and / or a vehicle-mounted communication unit.

[0025] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0027] Figure 1 is a structural schematic diagram of a vehicle-to-everything system according to an embodiment of the present application;

[0028] Figure 2 is a flowchart of a time synchronization method of a vehicle-to-everything system according to an embodiment of the present application;

[0029] Figure 3 is a structural schematic diagram of a high-precision clock estimation system of a vehicle-to-everything system according to an embodiment of the present application;

[0030] Figure 4 is a structural block diagram of a time synchronization device of a vehicle-to-everything system according to an embodiment of the present application;

[0031] Figure 5 is a flowchart of a time synchronization method of a vehicle-to-everything system according to an embodiment of the present application;

[0032] Figure 6 is a structural block diagram of a time synchronization device of a vehicle-to-everything system according to an embodiment of the present application;

[0033] Figure 7 is a structural block diagram of a vehicle networking system according to an embodiment of the application.

[0034] Reference sign: time synchronization device 2 of a vehicle networking system;

[0035] First acquisition module 21; second acquisition module 22; determination module 23;

[0036] Vehicle networking system 3; V2X device 31. DETAILED DESCRIPTION

[0037] The embodiments of the application are described in detail below, and the embodiments described with reference to the accompanying drawings are exemplary, and the embodiments of the application are described in detail below.

[0038] V2X is referred to as vehicle networking in 3GPP (3rd Generation Partnership Project, 3rd Generation Partnership Project) standards, and is based on a cellular network, which is a key technology for future intelligent transportation systems, so that vehicles, road infrastructure, and multiple road infrastructure can communicate with each other, so that vehicles can obtain real-time traffic conditions, traffic road information, pedestrian information, and a series of traffic information, enhance the perception of vehicles to improve driving safety, reduce congestion, improve traffic efficiency, and provide vehicle entertainment information, etc.

[0039] V2X technology uses wireless communication between vehicles, between vehicles and roadside infrastructure, and between vehicles and pedestrians to perceive the surrounding conditions of vehicles in real time, to provide timely warnings and help prevent 80% of all traffic accidents, making V2X technology a research hotspot for solving road safety problems in the world.

[0040] In 3GPP, the LTE V2X trusted communication delay should be less than 100ms, and the biggest advantage of V2X communication is low latency, and the prerequisite for low latency is time synchronization between communication devices, but the development of V2X is a gradual process, and V2X technology needs to meet the time-specific precision as a prerequisite, and the 3GPP standard defines that the time deviation is less than 391ns. However, when the V2X device enters a long tunnel, there is no wireless signal and the GNSS signal is lost, and if there is no unified time server, the time accuracy of the V2X device cannot be guaranteed, resulting in V2X communication interruption and unavailability, so in the entire vehicle networking, maintaining the availability of V2X will be the top priority, and therefore guaranteeing the time synchronization technology is also an important prerequisite for V2X to work normally.

[0041] In related technologies, when a vehicle is not in a tunnel, it can communicate with GNSS to obtain the time transmitted by GNSS in real time for time synchronization. When a vehicle enters a tunnel, it cannot communicate with GNSS to obtain the time, and time errors may cause traffic accidents. Therefore, in areas without GNSS coverage, a time source server, such as a time synchronization server, is set up, or wired and fiber optic connections are established to synchronize the vehicle's time. Wired and fiber optic connections have high requirements for deployment environment and cycle, increasing production costs.

[0042] Therefore, in the vehicle-to-everything (V2X) system of this embodiment, when a vehicle enters a tunnel, the vehicle is controlled to enter a V2X out-of-synchronization state, receive the synchronization broadcast signal of other V2X devices in the tunnel that are in a time synchronization state, use the signal as a reference signal, calculate the target time offset value and obtain the corrected final accurate time, so that the V2X devices in the out-of-synchronization state can obtain accurate time information.

[0043] The following is an example of the vehicle networking system according to an embodiment of the present invention.

[0044] like Figure 1 As shown, the vehicle-to-everything (V2X) system of this embodiment includes multiple V2X devices, such as Roadside Units (RSUs) supporting V2X communication functions set up on both sides of the tunnel, and / or Onboard Units (OBUs) mounted on vehicles. Each communication entity can communicate and interact through V2X technology, thereby improving the vehicle's perception of the entire traffic system. The interior of a tunnel is an area without GNSS coverage. Typically, the tunnel entrance and exit have GNSS coverage, while the interior lacks it. RSUs within the tunnel are divided into anchor RSUs and other RSUs. RSUs located at the tunnel entrance and exit that can receive GNSS signals are marked as anchor RSUs because they can obtain GNSS time sources and their V2X functionality is normal. RSUs located inside the tunnel, unable to receive GNSS, can only obtain time information through other means and are marked as other RSUs.

[0045] GNSS, or Global Navigation Satellite System, is a space-based radio navigation and positioning system that can provide users with all-weather three-dimensional coordinates, velocity, and time information at any location on the Earth's surface or in near-Earth space.

[0046] Roadside Units (RSUs) provide V2X and wireless connectivity for infrastructure such as roadside traffic lights, cameras, and various ETC (Electronic Toll Collection) devices. RSUs can provide V2X-based information broadcasting, such as traffic light times, intersection speed limits, and traffic congestion information, while also providing vehicles with high-precision maps and other services.

[0047] Onboard Unit (OBU) is typically a TBOX (Telematics Box), TCAN (Telematics Controller Area Network), or a vehicle-mounted unit. It is primarily installed in vehicles to collect vehicle signals and information, providing V2X connectivity and wireless internet access. Internet connectivity modules (such as 5G / 4G modules) are optional; in some scenarios or setups, only a V2X module may be present without wireless internet (e.g., a 5G / 4G module). Through V2X communication, it provides or receives warning information for the driver, and can also control some of the vehicle's auxiliary functions, interact with the vehicle's autonomous driving system, and share information, providing information input and network connectivity for the autonomous driving system.

[0048] The following is combined with Figures 1-3 This invention describes a time synchronization method for a vehicle-to-everything (V2X) system according to an embodiment of the present invention.

[0049] like Figure 2 As shown, the time synchronization method of the vehicle networking system in this embodiment of the invention includes at least steps S1-S3.

[0050] Step S1: Obtain the synchronization broadcast signal provided by the first V2X device in time synchronization state.

[0051] The time synchronization status includes the non-out-of-synchronization status and the status after the out-of-synchronization status has been completed; the first V2X device includes RSU device, OBU device and any other V2X-enabled device, which has completed time synchronization. The synchronization broadcast signal includes device identifier, source timestamp, subframe interval and frequency offset field. By obtaining the synchronization broadcast signal, a data foundation is provided for the time synchronization of the vehicle network system.

[0052] In this embodiment, when a V2X device enters a state of being out of sync, a first V2X device in a time-synchronized state is identified around the out-of-sync V2X device, and a correlation channel is established between the first V2X device and the time-synchronized first V2X device. The first V2X device sends a synchronization broadcast signal to the out-of-sync V2X device through the correlation channel, including, for example, device identifier, subframe interval, source timestamp, and frequency offset field. It is understood that the device identifier is generally obtained through the device IMEI (International Mobile Equipment Identity) or device vendor code identifier; the source timestamp is accurate to the nanosecond level. The out-of-sync V2X device obtains the synchronization broadcast signal provided by the first V2X device through the correlation channel and adds a timestamp field and crystal oscillator offset to the synchronization broadcast signal, providing a data basis for time synchronization of the vehicle-to-everything (V2X) system.

[0053] Step S2: Obtain the target time offset value.

[0054] The target time offset value is the time difference between the out-of-sync V2X device and the first V2X device in a synchronized state. By obtaining the target time offset value, the out-of-sync V2X device can be time-calibrated.

[0055] In this embodiment, after obtaining the synchronization broadcast signal provided by the first V2X device in a time synchronization state, the target time offset value is determined based on the device identifier, source timestamp, subframe interval, and frequency offset field in the synchronization broadcast signal, so as to perform real-time and accurate time calibration of the V2X device.

[0056] Step S3: Determine the final precise time for synchronization with the first V2X device based on the target time offset value and the synchronization broadcast signal.

[0057] In this embodiment, after determining the target time offset value, the final accurate time for synchronization with the first V2X device is determined based on the source timestamp of the synchronization broadcast signal and the target time offset value. After determining the final accurate time for synchronization with the first V2X device, the final accurate time is input to the out-of-sync V2X device to synchronize the out-of-sync V2X device, so that the time information of the out-of-sync V2X device is restored to normal. The restored V2X device can normally send and receive the synchronization broadcast signal.

[0058] According to the time synchronization method of the vehicle-to-everything (V2X) system of the present invention, when a V2X device enters a state of out-of-synchronization, a synchronization broadcast signal provided by a first V2X device in a time synchronization state is obtained, a target time deviation value is obtained based on the synchronization broadcast signal, the time is corrected based on the target time deviation value, and a final accurate time is obtained. By performing time synchronization based on the synchronization broadcast signal provided by the first V2X device, the V2X device in the out-of-synchronization state can obtain accurate time information, ensuring that V2X is applicable to more scenarios and preventing and reducing the accident rate of the system in tunnels.

[0059] In some embodiments, obtaining the target time offset value includes: parsing the synchronous broadcast signal to obtain the initial accurate time; obtaining the flight time based on the initial accurate time; and obtaining the target time offset value based on the flight time.

[0060] In this embodiment, after acquiring the synchronization broadcast signal provided by the first V2X device in a time synchronization state, the synchronization broadcast signal is parsed, and the initial accurate time is obtained based on the device identifier, source timestamp, subframe interval, and frequency offset field in the synchronization broadcast signal. After obtaining the initial accurate time, since the synchronization broadcast signal is transmitted at a relatively fixed period, for example every 500ms, through a fixed transmission bandwidth and fixed subframe position of a fixed PRB (Physical Resource Block), and the timestamp field and crystal oscillator offset are added to the synchronization broadcast signal, the initial accurate time may deviate. Therefore, the difference between the initial accurate time and the relatively fixed period time is calculated, and the flight time is obtained based on the difference. After obtaining the flight time, the target time offset value is determined based on the time difference between the flight time and the relatively fixed period time.

[0061] In some embodiments, parsing the synchronous broadcast signal to obtain the initial accurate time includes: parsing the synchronous broadcast signal to obtain the source time, demodulation processing time and frequency offset of the synchronous broadcast signal; and determining the initial accurate time based on the source time, demodulation processing time and frequency offset.

[0062] In this embodiment, after obtaining the synchronization broadcast signal provided by the first V2X device in a time synchronization state, the source timestamp in the synchronization broadcast signal is used to indicate the precise time when the synchronization broadcast signal was sent, and the source time of the synchronization broadcast signal is synchronized according to the source timestamp; the subframe interval in the synchronization broadcast signal is used to indicate the subframe position in the transmission of the synchronization broadcast signal, and the subframe offset and demodulation processing time are obtained according to the subframe interval; the frequency offset field in the synchronization broadcast signal is used to calculate the frequency offset of the first V2X device that sent the synchronization broadcast signal. By parsing the synchronization signal, the source time, demodulation processing time and frequency offset are obtained, thereby determining the initial precise time.

[0063] In some embodiments, obtaining flight time based on initial accurate time includes: receiving synchronous broadcast signals multiple times consecutively; parsing each received synchronous broadcast signal to obtain the initial accurate time corresponding to each synchronous broadcast signal; obtaining a preset reception interval time for multiple consecutive initial accurate times; and obtaining flight time based on the initial accurate time and the preset reception interval time.

[0064] In this embodiment, synchronous broadcast signals are received multiple times consecutively. Each received synchronous broadcast signal is analyzed to obtain the source time, demodulation processing time, and frequency offset of each synchronous broadcast signal. Based on these parameters, multiple corresponding initial accurate times are determined. After determining multiple corresponding initial accurate times, the average of the multiple initial accurate times is taken to reduce errors. At the same time, the preset reception interval time of the multiple consecutive initial accurate times is obtained. The difference between the multiple consecutive initial accurate times and the preset reception interval time is calculated to obtain the flight time. By obtaining the flight time, the air network delay time can be calculated, thereby calculating the final accurate time.

[0065] For example, when receiving two synchronous broadcast signals, the first synchronous broadcast signal B1 is received with a source time of T1, a demodulation processing time of t1, a subframe interval of n1, and a frequency offset of t1'. Based on the above parameters, the initial accurate time tm1 is calculated, i.e., tm1 = T1 + t1 + t1'. When receiving the second synchronous broadcast signal B2, the source time is T2, the demodulation processing time is t2, the subframe interval is n2, and the frequency offset is t2'. Based on the above parameters, the initial accurate time tm2 is calculated, i.e., tm2 = T2 + t2 + t2'.

[0066] After determining the two initial precise times, the preset reception interval between the two initial precise times is set to, for example, 500ms. Then the flight time is the difference between the source time T2 of the second synchronous broadcast signal, the source time T1 of the first synchronous broadcast signal, and the preset reception interval, i.e., T2-T1-500ms.

[0067] In some embodiments, obtaining a target time offset value based on flight time includes: determining an initial time offset value based on flight time, demodulation processing time, and frequency offset; determining a confidence percentage based on the initial time offset value; and using the initial time offset value as the target time offset value when the confidence percentage is greater than a preset confidence threshold.

[0068] In this embodiment, after obtaining the flight time, the initial time deviation value between the initial accurate time and the synchronous broadcast signal is determined based on the demodulation processing time, frequency offset, and flight time. After determining the initial time deviation value, the confidence percentage is determined based on the initial time deviation value combined with the signal strength and temperature of the synchronous broadcast signal received by the system.

[0069] The confidence level can be preset for each time calculation unit, or the confidence level can be calculated periodically. For example, the initial time offset value can be calculated for each unit over a period of time and compared with the GNSS time. The error weighted average ratio is then used to obtain the confidence level.

[0070] After determining the confidence percentage, the relationship between the confidence percentage and the preset confidence threshold is judged. If the confidence percentage is greater than the preset confidence threshold, it is considered that the time synchronization accuracy of the V2X device is met, and the initial time offset value is used as the target time offset value. If the confidence percentage is less than or equal to the preset confidence threshold, it is considered that the time synchronization accuracy of the V2X device is not met, and the synchronization broadcast signal is re-analyzed.

[0071] In some embodiments, determining the final precise time for synchronization with the first V2X device based on a target time offset value and a synchronization broadcast signal includes: determining the source time for receiving the synchronization broadcast signal; and determining the final precise time for V2X device synchronization based on the source time and the target time offset value.

[0072] In this embodiment, after determining the target time offset value, the source time is determined by the time information of the received synchronization broadcast signal. The difference between the source time and the target time offset value is calculated and used as the final accurate time for V2X device synchronization, so as to meet the time accuracy requirements at the ns level. All time synchronization is completed at the physical layer or media access control layer, without the need for higher-level protocols to intervene in parsing and decoding data, which greatly reduces internal processing time and improves time accuracy.

[0073] In some embodiments, acquiring a synchronization broadcast signal provided by a first V2X device in a time-synchronized state includes: establishing a synchronization channel; and using the synchronization channel to acquire the synchronization broadcast signal provided by the first V2X device in a time-synchronized state.

[0074] In an embodiment, such as Figure 3 The diagram shown is a structural schematic of a high-precision clock estimation system for a vehicle-to-everything (V2X) system according to an embodiment of the present invention. Based on the data channel established between the out-of-sync V2X device and the first V2X device, a synchronization channel is established. The first V2X device sends a synchronization broadcast signal to the out-of-sync V2X device through the synchronization channel. The out-of-sync V2X device uses the synchronization channel to obtain the synchronization broadcast signal provided by the first V2X device, which is in a time-synchronized state. The data channel is the traditional 3GPP-defined correlation channel, typically used for transmitting V2X data; the synchronization channel is typically used for broadcasting synchronization signals.

[0075] The first V2X device provides time source synchronization for out-of-sync V2X devices. Instead of using traditional message or data transmission mechanisms, the synchronization channel is introduced in the V2X time and frequency domains. This synchronization channel only listens when the V2X device is out of sync and sends data when the V2X device is in a synchronized state, which greatly reduces system resource consumption.

[0076] In some embodiments, before acquiring the synchronization broadcast signal provided by the first V2X device in a time synchronization state, the method further includes: determining that the V2X device has entered a loss-of-synchronization state and controlling the V2X device to stop sending the synchronization broadcast signal.

[0077] In this embodiment, before acquiring the synchronization broadcast signal provided by the first V2X device in a time synchronization state, it is determined whether the V2X device has entered a state of being out of sync. If the V2X device is in a state where it cannot normally acquire positioning data and time source data from GNSS, since V2X messages are time-sensitive, erroneous delay messages will cause the packet loss rate of the entire system to increase, and other devices will not be able to determine the specific time of the data, which will lead to incorrect judgments for assisted driving. Therefore, the V2X device is controlled to stop sending the synchronization broadcast signal, thereby controlling the V2X devices that are sending normally in the system to be reliable V2X time devices and meet the accuracy requirements of time synchronization.

[0078] In some embodiments, obtaining a target time offset value includes: acquiring multiple standard reference times; determining multiple time offset values ​​and multiple confidence percentages corresponding to the multiple standard reference times; and determining a target time offset value based on the multiple time offset values ​​and the multiple confidence percentages.

[0079] In an embodiment, such as Figure 4 The diagram shown is a structural schematic of a high-precision clock estimation system for a vehicle-to-everything (V2X) system according to an embodiment of the present invention. The estimation system includes: a DR (Dead-Reckoning) data module, a V2X time module, a wireless network time module, an onboard ECU (Electronic Control Unit) time module, an offset calculation module, and a clock output module.

[0080] The DR (Depth-of-Traffic) data module, or Inertial Navigation Measurement Unit, typically consists of a gyroscope, accelerometer, various sensors, and an algorithm processing unit. DR technology is a commonly used navigation and positioning technology. Its basic principle is to use direction and velocity sensors to calculate the vehicle's instantaneous position, and to obtain its own trajectory and time accuracy estimates by measuring acceleration and rotation angles. It is responsible for calculating the GNSS time estimate after the vehicle enters the tunnel, achieving continuous autonomous positioning. Vehicle positioning usually combines DR with GPS (Global Positioning System), leveraging the strengths of both to compensate for their respective weaknesses. This ensures that V2X devices can provide relatively accurate navigation information to the vehicle at all times. On one hand, the accurate positioning results of GPS can assist in the initialization of DR, and it can be used periodically to correct DR positioning errors online. On the other hand, when GPS positioning fails, the V2X device can automatically switch to DR navigation mode until GPS reception is restored, at which point the system returns to the combined GPS and DR navigation mode. Therefore, when a vehicle enters a tunnel and loses synchronization, the standard reference time can be obtained through the DR data module, and the corresponding time offset value and confidence percentage can be determined.

[0081] The V2X time module is responsible for receiving the synchronization broadcast signal from the RSU. Therefore, when a vehicle enters a tunnel and is out of sync, the standard reference time can be obtained through the V2X time module, and the corresponding time offset value and the confidence percentage of the time offset value can be determined.

[0082] The wireless network time module is responsible for synchronizing device information via the wireless network. Therefore, when a vehicle enters a tunnel and becomes out of sync, it can obtain the standard reference time through the wireless network time module, determine the time offset value, and the confidence percentage corresponding to the time offset value. Furthermore, when the vehicle receives time synchronization information from other cellular networks such as 5G, it can synchronize its time through the wireless network.

[0083] When a vehicle enters a tunnel and loses synchronization, the onboard ECU's time module obtains a standard reference time from other ECU components in the vehicle, such as the intelligent module controller, and determines the corresponding time offset value and the confidence percentage of that time offset value. This allows other ECU components or connected devices in the vehicle to obtain the final accurate time.

[0084] When a vehicle enters a tunnel and becomes out of sync, the offset calculation module uses the GNSS time estimated by the V2X time module and DR data module as the input source to obtain the standard reference time, determine the corresponding time offset value, and correct the local clock signal. Different time synchronization modules can determine different standard reference times and time offset values ​​according to different algorithms. The offset calculation module determines the confidence percentage corresponding to the time offset value based on the vehicle temperature, speed, and crystal oscillator status.

[0085] The above modules are used to obtain multiple time offset values ​​and multiple confidence percentages, thereby determining the target time offset value based on the multiple time offset values ​​and multiple confidence percentages.

[0086] In some embodiments, determining a target time offset value based on multiple time offset values ​​and multiple confidence percentages includes: if at least two of the multiple confidence percentages are greater than a preset confidence threshold, then weighting the time offset values ​​corresponding to the at least two confidence percentages to obtain a target time offset value; if one of the multiple confidence percentages is greater than a preset confidence threshold, then using the time offset value corresponding to the confidence threshold being greater than the preset confidence threshold as the target time offset value.

[0087] In this embodiment, after obtaining multiple time offset values ​​and multiple confidence percentages, it is determined whether at least two of the multiple confidence percentages are greater than a preset confidence threshold. If at least two of the multiple confidence percentages are greater than the preset confidence threshold, the offset calculation module performs a weighted calculation on the time offset values ​​corresponding to the at least two confidence percentages to obtain the target time offset value. If one of the multiple confidence percentages is greater than the preset confidence threshold, the time offset value corresponding to the confidence threshold being greater than the preset confidence threshold is taken as the target time offset value.

[0088] The offset calculation module determines the final accurate time based on the target time offset value, which is then used as the time source input to the V2X module, enabling the V2X module to function properly.

[0089] The clock output module is responsible for outputting a reference clock signal. After the out-of-sync V2X device completes time synchronization, the clock output module normally outputs a 1pps pulse, and the V2X device enters normal transmission and reception of synchronization broadcast signals.

[0090] The following is for reference. Figure 5 An example is provided to illustrate the time synchronization method of the vehicle networking system according to an embodiment of the present invention.

[0091] like Figure 5 As shown, the time synchronization method of the vehicle networking system in this embodiment of the invention includes at least steps S11-S22.

[0092] Step S11: Determine that the V2X device has entered a state of being out of sync, and control the V2X device to stop sending synchronization broadcast signals.

[0093] Step S12: Establish a synchronization channel and use the synchronization channel to obtain the synchronization broadcast signal provided by the first V2X device in time synchronization state.

[0094] Step S13: Analyze the synchronous broadcast signal to obtain the source time, demodulation processing time and frequency offset of the synchronous broadcast signal, and determine the initial accurate time based on the source time, demodulation processing time and frequency offset.

[0095] Step S14: Receive synchronous broadcast signals multiple times consecutively, parse each received synchronous broadcast signal to obtain the initial accurate time corresponding to each synchronous broadcast signal, obtain the preset reception interval time of multiple consecutive initial accurate times, and obtain the flight time based on the initial accurate time and the preset reception interval time.

[0096] Step S15: Determine the initial time offset value based on the flight time, demodulation processing time, and frequency offset; determine the confidence percentage based on the initial time offset value.

[0097] Step S16: Determine whether the confidence percentage is greater than the preset confidence threshold. If yes, proceed to step S17; otherwise, proceed to step S13.

[0098] Step S17: Use the initial time offset value as the target time offset value.

[0099] Step S18: Determine the source time of the received synchronization broadcast signal, and determine the final accurate time for V2X device synchronization based on the source time and the target time offset value.

[0100] Step S19: Obtain multiple standard reference times, and determine multiple time offset values ​​and multiple confidence percentages corresponding to the multiple time offset values ​​based on the multiple standard reference times.

[0101] Step S20: Determine whether there are at least two confidence percentages that are greater than the preset confidence threshold. If so, proceed to step S21; otherwise, proceed to step S22.

[0102] Step S21: Perform a weighted calculation on the time offset values ​​corresponding to at least two confidence percentages to obtain the target time offset value.

[0103] Step S22: The time offset value corresponding to the confidence threshold being greater than the preset confidence threshold is taken as the target time offset value.

[0104] According to the time synchronization method of the vehicle-to-everything (V2X) system of the present invention, when a V2X device enters a state of out-of-synchronization, a synchronization broadcast signal provided by a first V2X device in a time synchronization state is obtained, a target time deviation value is obtained based on the synchronization broadcast signal, the time is corrected based on the target time deviation value, and a final accurate time is obtained. By performing time synchronization based on the synchronization broadcast signal provided by the first V2X device, the V2X device in the out-of-synchronization state can obtain accurate time information, ensuring that V2X is applicable to more scenarios and preventing and reducing the accident rate of the system in tunnels.

[0105] The following is for reference. Figure 6 The time synchronization device 2 of the vehicle networking system according to an embodiment of the present invention is described.

[0106] like Figure 6 As shown, the time synchronization device 2 of the vehicle networking system in this embodiment of the invention includes: a first acquisition module 21, a second acquisition module 22, and a determination module 23, wherein,

[0107] The first acquisition module 21 is used to acquire the synchronization broadcast signal provided by the first V2X device in the time synchronization state; the second acquisition module 22 is used to acquire the target time offset value; and the determination module 23 is used to determine the final accurate time of synchronization with the first V2X device based on the target time offset value and the synchronization broadcast signal.

[0108] In this embodiment, when a V2X device enters a state of being out of sync, the first acquisition module 21 identifies a first V2X device in a time-synchronized state around the out-of-sync V2X device and establishes a correlation channel with the first V2X device in a time-synchronized state. The first V2X device sends a synchronization broadcast signal to the out-of-sync V2X device through the correlation channel, including, for example, device identifier, subframe interval, source timestamp, and frequency offset field. It can be understood that the device identifier is generally obtained through the device IMEI (International Mobile Equipment Identity) or device vendor code identifier; the source timestamp is accurate to the nanosecond level. The out-of-sync V2X device obtains the synchronization broadcast signal provided by the first V2X device through the correlation channel and adds a timestamp field and crystal oscillator offset to the synchronization broadcast signal to provide a data basis for time synchronization of the vehicle network system. The time synchronization status includes the non-out-of-synchronization status and the status after the out-of-synchronization status has been completed; the first V2X device includes RSU device, OBU device and any other V2X-enabled device, which has completed time synchronization. The synchronization broadcast signal includes device identifier, source timestamp, subframe interval and frequency offset field. By obtaining the synchronization broadcast signal, a data foundation is provided for the time synchronization of the vehicle network system.

[0109] The second acquisition module 22 determines the target time offset value based on the device identifier, source timestamp, subframe interval, and frequency offset field in the synchronization broadcast signal, so as to perform real-time and accurate time calibration of the V2X device. The target time offset value is the time difference between the out-of-sync V2X device and the first V2X device in a synchronized state. By acquiring the target time offset value, the out-of-sync V2X device can be time-calibrated.

[0110] The determining module 23 determines the final accurate time for synchronization with the first V2X device based on the source timestamp of the synchronization broadcast signal and the target time offset value. After determining the final accurate time for synchronization with the first V2X device, the final accurate time is input to the out-of-synchronization V2X device to synchronize the out-of-synchronization V2X device, so that the time information of the out-of-synchronization V2X device is restored to normal. The restored V2X device can send and receive the synchronization broadcast signal normally.

[0111] According to the time synchronization method of the vehicle-to-everything (V2X) system of the present invention, when a V2X device enters a state of out-of-synchronization, a synchronization broadcast signal provided by a first V2X device in a time synchronization state is obtained, a target time deviation value is obtained based on the synchronization broadcast signal, the time is corrected based on the target time deviation value, and a final accurate time is obtained. By performing time synchronization based on the synchronization broadcast signal provided by the first V2X device, the V2X device in the out-of-synchronization state can obtain accurate time information, ensuring that V2X is applicable to more scenarios and preventing and reducing the accident rate of the system in tunnels.

[0112] The following is for reference. Figure 7 The vehicle networking system 3 of this invention is described in an embodiment.

[0113] like Figure 7 As shown, the vehicle networking system 3 of this embodiment includes: a time synchronization device 2 and a V2X device 31 as described in the above embodiment, wherein the V2X device 31 communicates with the time synchronization device 2 of the vehicle networking system.

[0114] According to the vehicle-to-everything (V2X) system 3 of the present invention, when a V2X device enters a state of being out of sync, it acquires a synchronization broadcast signal provided by a first V2X device in a time synchronization state, obtains a target time deviation value based on the synchronization broadcast signal, corrects the time based on the target time deviation value, and obtains the final accurate time. By performing time synchronization based on the synchronization broadcast signal provided by the first V2X device, the V2X device in the state of being out of sync can obtain accurate time information, ensuring that V2X is applicable to more scenarios and preventing and reducing the accident rate of the system in tunnels.

[0115] In some embodiments, the V2X device includes a roadside unit and / or an onboard communication unit.

[0116] According to the vehicle-to-everything (V2X) system 3 of the present invention, when a V2X device enters a state of being out of sync, it acquires a synchronization broadcast signal provided by a first V2X device in a time synchronization state, obtains a target time deviation value based on the synchronization broadcast signal, corrects the time based on the target time deviation value, and obtains the final accurate time. By performing time synchronization based on the synchronization broadcast signal provided by the first V2X device, the V2X device in the state of being out of sync can obtain accurate time information, ensuring that V2X is applicable to more scenarios and preventing and reducing the accident rate of the system in tunnels.

[0117] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0118] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A time synchronization method for a vehicle networking system, characterized in that, The vehicle-to-everything (V2X) system includes multiple V2X devices, and the time synchronization method includes: Acquire the synchronization broadcast signal provided by the first V2X device in time synchronization state; Obtaining the target time offset value includes: parsing the synchronization broadcast signal to obtain the initial precise time; obtaining the flight time based on the initial precise time; and obtaining the target time offset value based on the flight time. Obtaining the target time offset value based on the flight time includes: determining an initial time offset value based on the flight time, demodulation processing time, and frequency offset; determining a confidence percentage based on the initial time offset value; and using the initial time offset value as the target time offset value when the confidence percentage is greater than a preset confidence threshold. The final precise time for synchronization with the first V2X device is determined based on the target time offset value and the synchronization broadcast signal; The process of parsing the synchronous broadcast signal to obtain the initial precise time includes: The synchronous broadcast signal is analyzed to obtain the source time, demodulation processing time, and frequency offset corresponding to the synchronous broadcast signal; The initial precise time is determined based on the source time, the demodulation processing time, and the frequency offset. The flight time is obtained based on the initial precise time, including: Receive the synchronous broadcast signal multiple times consecutively; Each received synchronous broadcast signal is parsed to obtain the initial precise time corresponding to each synchronous broadcast signal; Obtain the preset reception interval time for multiple consecutive initial precise times; The flight time is obtained based on the initial accurate time and the preset reception interval.

2. The time synchronization method for a vehicle networking system according to claim 1, characterized in that, Determining the final precise time for synchronization with the first V2X device based on the target time offset value and the synchronization broadcast signal includes: Determine the source time for receiving the synchronous broadcast signal; The final precise time for V2X device synchronization is determined based on the source time and the target time offset value.

3. The time synchronization method for a vehicle networking system according to claim 1, characterized in that, Acquire the synchronization broadcast signal provided by the first V2X device in time synchronization state, including: Establish a synchronization channel; The synchronization channel is used to obtain the synchronization broadcast signal provided by the first V2X device in a time-synchronized state.

4. The time synchronization method for a vehicle networking system according to claim 1, characterized in that, Before acquiring the synchronization broadcast signal provided by the first V2X device in time synchronization state, the process also includes: If the V2X device is found to be out of sync, control the V2X device to stop sending the synchronization broadcast signal.

5. The time synchronization method for a vehicle networking system according to claim 1, characterized in that, Obtain the target time offset value, including: Obtain multiple standard reference times; Based on the multiple standard reference times, determine multiple time offset values ​​and multiple confidence percentages corresponding to the multiple time offset values; The target time offset value is determined based on a plurality of the stated time offset values ​​and a plurality of stated confidence percentages.

6. The time synchronization method for a vehicle networking system according to claim 4, characterized in that, Determining the target time offset value based on a plurality of said time offset values ​​and a plurality of said confidence percentages includes: If at least two of the multiple confidence percentages are greater than a preset confidence threshold, then the time offset values ​​corresponding to the at least two confidence percentages are weighted and calculated to obtain the target time offset value; If any one of the confidence percentages is greater than the preset confidence threshold, then the time offset value corresponding to the confidence threshold being greater than the preset confidence threshold is taken as the target time offset value.

7. A time synchronization device for a vehicle networking system, characterized in that, include: The first acquisition module is used to acquire the synchronization broadcast signal provided by the first V2X device in a time synchronization state; The second acquisition module is used to acquire the target time offset value; Obtaining the target time offset value includes: parsing the synchronization broadcast signal to obtain the initial precise time; obtaining the flight time based on the initial precise time; and obtaining the target time offset value based on the flight time. Obtaining the target time offset value based on the flight time includes: determining an initial time offset value based on the flight time, demodulation processing time, and frequency offset; determining a confidence percentage based on the initial time offset value; and using the initial time offset value as the target time offset value when the confidence percentage is greater than a preset confidence threshold. The determination module is used to determine the final accurate time of synchronization with the first V2X device based on the target time offset value and the synchronization broadcast signal; The process of parsing the synchronous broadcast signal to obtain the initial precise time includes: The synchronous broadcast signal is analyzed to obtain the source time, demodulation processing time, and frequency offset corresponding to the synchronous broadcast signal; The initial precise time is determined based on the source time, the demodulation processing time, and the frequency offset. The flight time is obtained based on the initial precise time, including: Receive the synchronous broadcast signal multiple times consecutively; Each received synchronous broadcast signal is parsed to obtain the initial precise time corresponding to each synchronous broadcast signal; Obtain the preset reception interval time for multiple consecutive initial precise times; The flight time is obtained based on the initial accurate time and the preset reception interval.

8. A vehicle networking system, characterized in that, include: The time synchronization device for the vehicle networking system as described in claim 7; The V2X device communicates with the time synchronization device.

9. The vehicle networking system according to claim 8, characterized in that, The V2X equipment includes a roadside unit and / or an on-board communication unit.

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