Application Based On OFDMA Access Technology In The Wave

With the number of civilian vehicles increasing, our transportation system is under increasing pressure, our cities and residents are plagued by the driving problems, parking problems, traffic safety problems and so on. On the other hand, the rapid development of wireless communication technology and the advance of sensor technology can provide a method to solve the traffic congestion and other problems for the people who live in this era of the rapid development of science and technology. The new generation of intelligent transportation system-wireless access in vehicular environments(WAVE)was put forward to solve the traffic problem.This article will introduce OFDMA access technology to IEEE802.11 p which used in the WAVE, the original network communication channel used in WAVE is divided into sub-channels simultaneously accessed by multiple car unit, and design a receiver structure for this architecture. This receiver structure can achieve multiple access uplink synchronization signals, according to the characteristics of high equipment demand, low-cost requirements in the practical application; design a resource-saving structure. The main contents of the work as follows:1) Firstly, to make the OFDMA access technology has a good compatibility in IEEE802.11 p standard, designed an OFMDA / CSMA hybrid MAC layer protocol, and make a reasonable arrangement for using OFDM and OFDMA mode of communication under different conditions, so the system not only has simple structure, but also has high system performance by improve the throughput of the system at the largest extent.2) Under the framework of OFMDA / CSMA hybrid MAC layer protocol, designed a road side unit(RSU) uplink synchronization receiver structure, and combined this structure with a traditional transmitter receiver in IEEE802.11 p standard system, allowing the system to achieve the introduction of OFDMA access technology under the premise of change the original system as little as possible. Firstly, gave the design scheme and algorithms of each modules of the system, and simulated all modules in the system to design and verify the algorithm, simulation results show that it meets all parameters and performance requirements of the original standards which proved the correctness and effectiveness of the system design,3) Described the design scheme of modules on FPGA, gave the implementation plan of each modules and the FPGA implementation algorithms of complex algorithms in designed modules. We used Quartus Ⅱ 11.1 to compile the modules and used Modelsim to make functional simulation of these modules, which in order to verify the correctness of its logic function.