Study And FPGA Implementation Of Channel Estimation Technology In Vehicular OFDM Communication System

Vehicle communication network can greatly improve the traffic efficiency and reduce the loss of the life and property of drivers and pedestrians by directly establishing vehicle-to-vehicle and vehicle-toinfrastructure wireless communication, and has a broad application prospect in the field of intelligent transportation and attracted much attention. The physical layer of the vehicular communication system adopts OFDM. Vehicular channel have larger doppler spread and delay spread compared to relatively stable indoor environment, which results in the amplitude and phase of the OFDM signal distortion. How to conduct an effective channel estimation becomes the key to ensure reliable vehicle communication. This article aims at the research and FPGA implementation of channel estimation technology for OFDM communication system in vehicular environment. The main work includes the following three aspects:(1) Based on the analysis of the concrete realization of the physical layer of the vehicular communication system and characteristics of the vehicular channel, build a complete OFDM baseband system simulation platform using simulink, and verify the correctness of the simulation platform by measured zero bit error rate without the influence of channel.(2) Analyzed the limitations of traditional channel estimation algorithms when applied to the vehicular environment from two aspects which are the pilot frequency distribution and time-varying characteristics of the vehicle channel. On the basis of the analysis of existing improvement decision feedback channel estimation methods, This paper proposed a decision-directed channel estimation method based on the information of channel variation carried by the channel response of postamble for vehicular communication environment with both large doppler spread and large delay spread. Simulation results show that the proposed method can obtain much better packet error rate(PER) performance compared to currently effective channel estimation methods.(3) Proposed a FPGA hardware implement scheme for the improved channel estimation method. In the case of the same input data source, the function simulation output of the demodulation module of the FPGA design is consistent with the demodulation output of the simulink model,which shows that the function of the FPGA design is correct and the proposed channel eatimation method is practical.