Channel Estimation and Equalization in the Presence of Timing Offset in MB-OFDM Systems

This paper presents low-complexity preamble-based channel estimation and one-tap frequency-domain equalization for zero-padded MB-OFDM based UWB systems. The required circular convolution property of the received signal is obtained by means of an overlap-add method. The proposed low-complexity channel estimator for each band is developed by first averaging the over-lap-added received preamble symbols within the same band and then applying time-domain least-squares method followed by the discrete Fourier transform. By using the probability density functions of the UWB channel path delays, we also derive the statistics of the UWB channel models, and utilizing them we present several optimization criteria for our proposed channel estimation and equalization in the presence of timing offset. The effectiveness of our proposed methods and optimization criteria are confirmed by computer simulation results.