Research Of MAC Technology With QoS For CoITS Wireless Access Network

With the development of society and economy, the transportation is growing rapidly. As a result, the problems such as road congestion and traffic accidents have become more and more serious. CoITS (Cooperative Intelligent Transportation Systems) integrate advanced sensor technology, information technology and communication technology effectively and apply these technologies to each aspect in transportation. By means of real-time information exchange and intelligent processing technology, CoITS provide a new solution for the development of transportation informatization and become the future direction of transportation modernization. Cars and road infrastructures could communicate with each other based on the wireless access network of CoITS. Besides, different CoITS services have different requirements of QoS (Quality of Service). So how to provide wireless access communication with QoS between cars and infrastructures becomes the key technology of CoITS.The thesis focuses on the research of MAC (Media Access Control) technology with QoS of the CoITS wireless access network. The MAC technology includes access control mechanism, services bear methods and handover. On the basis of the comparison analysis of MAC technology of IEEE 802.11p and LTE, the MAC technology of CoITS wireless access network is researched which refers to TD-LTE MAC technology. The performance of random access CoITS services with the TD-LTE mechanism is analyzed in terms of theory and verified with simulation. A kind of efficient services bear method based on eMBMS (evolved Multimedia Broadcast Multicast Service) is designed to broadcast the CVIS (Cooperative Vehicle Infrastructure Service) and multicast the PTT (Push to Talk) service. The performance of the services bearing with eMBMS is verified by simulation. After analysis in theory and simulation to the TD-LTE hard handover assisted by UE, a handover method based on dual connection is proposed. The dual connection handover can not only simplify the signal interaction between eNodeBs, but also provide a good performance.