Modeling and Estimation of Wireless OFDM Channels by Using Time-Frequency Analysis

Orthogonal frequency division multiplexing (OFDM) has become a very popular method for high data rate wireless communications because of its advantages over single carrier modulation schemes on multipath, frequency selective fading channels. However, intercarrier interference, due to Doppler frequency shifts, and multipath fading severely degrade the performance of OFDM systems. Estimation of channel parameters is required at the receiver. In this paper, we present a channel modeling and estimation method based on the time-frequency representation of the received signal. The discrete evolutionary transform provides a time-frequency procedure to obtain a complete characterization of the multipath, fading, and frequency selective channels. Simulations are used to illustrate the performance of the proposed procedure and to compare it with other time-varying channel estimation techniques.