Research On Vehicle Networks MAC Layer For Safety Information Transmission In Multi-channel

With the rapid development of social economic, our country’s car ownership is growing fast, traffic jams and traffic accident has become a social problem. In order to improve the traffic and implement the intelligent of the urban traffic, the vehicle network technology arises at the historic moment.Therefore WAVE (Wireless Access in Vehicular Environments) technique has become a research hotspot in recent years, but as a result of the lack of reliable and scalable safety-related communication protocols, the large-scale arrangement of this system has not been approved. So, the research on reasonable and feasible safe information transmission scheme is of great significance.Vehicular safety applications require low latency communications and reliable packet dissemination for life saving safety messages, but the safety message latency for devices can be54milliseconds or even longer for enabling seven channel operations in WAVE, greater than the delay requirement of SAE J2735standard. A neighbor-assistant technique aimed to increase channel coverage and reduce latency in multi-channel vehicular communication networks, but the uncertainties of relay number and the channels on which relay randomly retransmits lead to high failure probability of safety message dissemination, resulting in a longer delay and higher collision rate.The thesis optimizes the delay and reliability of safety information in multi-channel operations based on the neighbor-assistant technique scheme, it proposed a handshaking scheme for V2V (Vehicle-to-Vehicle) relay recruitment and resource reservation based on RTS(Request to Send) frame/CTS (Clear To Send) frame exchange in the EDCA (Enhanced Distributed Channel Access) pattern for IEEE802.11p standard in the vehicle networks, reusing the RTS frame and ACK (Acknowledgement) frame in the handshaking mechanism. When the source vehicle detects the hazard signal, it coordinates with V2V relays and removes the relay has successfully competed and the channel has jumped one by one and establishs the corresponding system model. The simulation results show that the proposed scheme achieves improvement on transmission delay and packet success rate for safety information transmission and has a certain value for the safety information transmission in multi-channel vehicular communication networks.