Guard interval assisted OFDM symbol-based channel estimation for rapid time-varying scenarios in IEEE 802.11p

Abstract

In the recent year, road accidents in India have drastically increased. Owing to this, there is a need for reliable and robust data transmission in vehicular communication. IEEE 802.11p standard is a dedicated wireless vehicular communication standard meant for outdoor applications. In this standard, one of the biggest challenges is robust channel estimation due to rapid time varying nature of the channel. The impact of channel interference on vehicular tovehicular (V2V) communication uctuates rapidly and unpredictably due to high mobility scenarios. However, IEEE 802.11p is developed without considering an impact of high mobility as it was originally derived from IEEE 802.11a standard, a standard meant for indoor applications. Thus, in this work, we are interested in estimating channel for V2V communication systems. We reviewed prior work on channel estimation in IEEE 802.11p standard and have made two significant research contributions: First, we propose a novel decision-directed recursive least squares (RLS) time-domain channel estimation method that utilizes the guard interval (GI) of every orthogonal frequency division multiplexing (OFDM) symbol to track time-varying channel. Analysis and simulation results demonstrate that the proposed scheme outperforms existing GI assisted channel estimation schemes. Although, this proposed scheme suffers with inter carrier interference (ICI). The second contribution of this work is even more significant. Here, we propose a new scheme that alleviates ICI in the previous proposed scheme. Proposed scheme utilizes the redundant space of GI (other than that required for cyclic pre x (CP) to combat ICI) to insert pseudorandom sequence (PRS) for channel estimation. A decision directed time-domain recursive least squares channel estimation method is proposed that utilizes the inserted PRS with CP. Simulation results show considerably improved bit error rate (BER) performance compared to the existing methods. Thus, proposed scheme enables robust channel equalization in rapidly time-varying channel with high Doppler spread.