A Novel Relative Speed Estimation Technique in WAVE Using Pilot Subcarriers

Wireless access in vehicular environment (WAVE) is a technology developed for high data rate vehicle-to-vehicle and vehicle-to-infrastructure communications. Accurate estimation of speed of a vehicular node is essential in applications of WAVE such as collision avoidance systems and intersection safety applications. A novel speed estimation technique in WAVE is presented in this paper. The method estimates the relative speed of a vehicle using the Doppler shift which causes frequency offset in the received orthogonal frequency division multiplexed subcarriers. The frequency offset in the received subcarriers is calculated using a cross correlation metric between the transmitted pilot subcarriers and the received pilot subcarriers. The method gives good estimates of relative speed even at low signal to noise ratios and the simulations demonstrate that wide range of speeds (0 to 360 km/h) can be accurately estimated.