As part of intelligent transport system (ITS) technology, vehicular ad hoc network (VANET) offers convenience coordination between moving vehicles. A moving vehicle could be move at a very high speed, producing the Doppler Effect that damages OFDM symbols and also causes inter-carrier interference (ICI). Also, the scatterer along the vehicle generates many delays in vehicle to vehicle or vehicle to infrastructure communication system. This paper discussed VANET technology in comparison with 802.11a technology as they have many differences in adapting to user's mobility. The Doppler effect resulted from user's mobility with high speed was investigated as the main parameter in this paper to deliver a better solution in subsequent research. The results of this preliminary study were the Doppler shift, multipath delay, orthogonality parameter in OFDM, power spectral density of VANET and the influence of multipath delay in power spectral density. These preliminary results could be used as a reference in the implementation of future research to resolve the Doppler effect.