Research And Application Of Dedicated Short Range Communication And Positioning Technology In Internet Of Vehicles

Traffic problems have attracted more and more attention with the increase of travel demand. Internet of vehicles is a main solution in intelligent transportation fields, since it considers roads, vehicles as a whole system. Howerver, most researchs of telematics in China still stay in sensing layer. Besides, it lacks uniform standards or applications in communication layer and application layer.This thesis studies dedicated short range communication technology, positioning technology, and develops vehicle-infrastructure cooperation and intersection’ collision warning application based on the sensing layer and communication layer.First of all, Wi-Fi protocol stack architecture and driver mechanism are studied. The solutions are rapid access and short message protocol designs for vehicular environment, including sending and receiving data, switching channel and communication way between user space and kernel based on Wi-Fi protocol and state machine. The communication technology performs better compared with Wi-Fi. Combining pseudorange differential positioning technology with dedicated short range communication technology, the differential GPS system can code and decode differential correct data and transport them via short message protocol. Meanwhile, the system improves the precision and reduces the system cost. The vehicle-infrastructure cooperation has the function of two-way communication between road managers and travelers. The application can broadcast traffic service information, upload vehicle data and maintain the connections. Multi-thread and multiplexing programming methods are used in road side unit and on-board unit software in order to improve parallel processing ability. The intersection collision warning application reduces channel congestion by collecting and broadcasting vehicle information via road side unit. The warning system classifies possible collision after recieves surrounding vehicle data, which can minimize overhead caused by the unnecessary warning. Different warning methods are adopted in linear and lateral collision environment. It considers real driving conditions and corresponding safety factors when setting warning prameters. The offline test results prove the reliability of intersection collision warning system in real circumstance.At last, this thesis integrates former chapters contents as a whole system, introduces the hierarchical structure of the integrated system and hardware components, and finishes the test in real scenarios.The results show that dedicated short range communication technology has good performances and acceptable communication delay, the differential positioning technology has well position accuracy, the system meets the technical requirements and can be used in real traffic environment.