I. Introduction
To meet increased demand for high data rate transmission in wireless communication various digital schemes have evolved. Orthogonal Frequency Division Multiplexing (OFDM) can be considered as a promising modulation technique for achieving high spectral efficiency, negligible Inter Symbol Interference(ISI) and tolerance to multipath delay spread[4]. Now OFDM has emerged as a prominent scheme for digital communication applications such as digital television and audio broadcasting (DAB and DVB-T), DSL internet access, 4G mobile communications, IEEE 802.11 a, IEEE 802.16 and IEEE 802.20[2]. In OFDM, available spectrum is divided into different subcarriers and each subcarrier is modulated with a low data rate stream. The subcarriers are chosen in such a way that they are orthogonal to each other. Orthogonality property of subcarriers in OFDM prevents the use of guard bands thereby eliminating additional overhead.