A Low-Complexity and Efficient Channel Estimator for Multiband OFDM-UWB Systems

This paper proposes an efficient channel-estimation scheme for multiband (MB) orthogonal frequency-division multiplexing (OFDM)-based ultrawideband (UWB) communication systems and, more specifically, for practical implementation of low-cost, high-speed, UWB-based wireless universal serial bus (USB) devices. The proposed channel estimator consists of two stages. The first stage employs a simple least-squares (LS) method together with a frequency-domain smoothing operation that estimates the channel using the available training sequence. The second stage uses this channel estimate to detect the frame header and then refines the channel estimate by using a decision-directed technique. The mean-squared error performance and computational complexity of the proposed scheme are analyzed. Numerical examples show that the proposed scheme substantially outperforms the conventional LS approach and that it performs comparably to the maximum-likelihood estimator, under various highly noisy multipath channel conditions.