Enhanced Channel Estimation Algorithm for Dedicated Short-Range Communication Systems

Abstract

The Dedicated Short-Range Communication (DSRC) has been widely accepted as a promising wireless technology for enhancing traffic safety. In such Keywords: dedicated short range communications (DSRC), IEEE 802.11p standard, orthogonal frequency division multiplexing (OFDM), channel estimationCopyright © 2015 Universitas Ahmad Dahlan. All rights reserved. IntroductionDedicated Short-Range Communications (DSRC) is a wireless communication technique that enhances the safety and efficiency of transportation systems by enabling for a high-speed data exchange between vehicles. The U.S. Department of Transportation has estimated that vehicle-to-vehicle (V2V) communication can be used to manage up to 82% of all crashes arising from unimpaired drivers [1]. Currently, the most common worldwide DSRC standard is the IEEE 802.11p [2], which is based on orthogonal frequency division multiplexing (OFDM) [3]. Due to the high mobility of vehicles, the channels within the vehicular communication scenarios vary significantly in both time and frequency domain. Compared to the indoor channels, the time-varying characteristic of wireless propagation channels is a severe obstacle for reliable packet delivery. We focus on the practical methods for improving the reliability of V2V communications using enhanced channel estimation inherent to the IEEE 802.11p standard.The V2V channel propagation characteristics differ significantly from those of cellular and indoor stationary channels, especially in terms of their frequency-selectivity, time-selectivity, and associated fading statistics [4,5]. Time-variation results in a short channel coherence time, which causes the channel to change significantly from the start of the packet to the end of the packet. A commercially-available channel estimation scheme for chip set implementation in an indoor environment is the preamble-based least square (LS) [3] estimator. In the V2V communication environment, however, the LS estimator will significantly degrade system performance because it neglects the time-varying characteristic. A simple and accurate method to trace the time-varying channel is a linear interpolation either in the frequency direction only or the time-frequency-direction [6][7][8][9]. However, only four sub-carriers are allocated as pilots in the IEEE 802.11p standard, and they are not spaced closely enough to accurately sample the