We propose to apply DSRC using OFDM to roadside-vehicle communication system as a means to overcome frequency selective fading, shadowing and high-speed hand-over difficulties. We optimized the transmission rate of a subcarrier which is a transmission parameter of the OFDM system. Our goal is to achieve a BER of less than 10/sup -5/ under the conditions of transmission rate 2.048 Mbps, carrier frequency 5.8 GHz, vehicle speed 180 km/h, simulcasting of several roadside transmitters, maximum delay of less than 1 /spl mu/sec and utilizing forward error correction (FEC). We developed the transmitter and receiver of DQPSK-OFDM system in 5.8 GHz band and measured the BER performance to show that OFDM system was applicable to roadside-vehicle communication system.