In the V2X system, the correct decisions in many scenarios require the V2X device node clock synchronization, so that the time or frequency error between each network node device remains within a reasonable error level. The high-precision time service of multi-source fusion is more important in the scene where GNSS signal is blocked or multi-sensor fusion requires high signal accuracy. In addition, in the automatic driving technology, the time delay generated at different stages of perception, planning and execution needs to be considered. The signal positioning of running vehicles needs to control the synchronous time error at the nanosecond level.
This paper provides a high-precision time synchronization method applied to V2X. The method adopts multi clock source fusion. It includes three service modes: GNSS, cellular data and local clock. It also fully considers the priority of clock source and the transmission time delay of multiple interactions in the time service process, including hardware and software. Hardware depends on time service and software depends on compensation. The experimental results show that RSU and OBU can achieve synchronization time error by using multi-source fusion clock source: the timing accuracy of each module in OBU meets RMS 30ns and 99% 60ns, and the timing accuracy of OBU and OBU, as well as OBU and other vehicle body sensors is 99% 50ms. It can also operate reliably in the most challenging environment and improve the robustness of key applications.