I. Introduction
As a multicarrier modulation technique, orthogonal frequency division multiplexing (OFDM) [1], [2] has gained popularity in a number of applications including digital audio broadcasting (DAB), terrestrial digital video broadcasting (DVB-T), the IEEE 802.11a standard for wireless local area networks (WLAN) and the IEEE 802.16d standard for wireless metropolitan area networks (WMAN), owing to its high bandwidth efficiency and robustness to multipath fading.