ICASSP '09 Proceedings of the 2009 IEEE International Conference on Acoustics, Speech and Signal Processing
Optimal training for block transmissions over doubly selective wireless fading channels
IEEE Transactions on Signal Processing
Time-Variant Channel Estimation Using Discrete Prolate Spheroidal Sequences
IEEE Transactions on Signal Processing
MMSE decision-feedback equalizers: finite-length results
IEEE Transactions on Information Theory
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We consider a decision-directed tracking approach to doubly-selective channel estimation exploiting the complex exponential basis expansion model (CE-BEM). The time-varying nature of the channel is well captured by the CE-BEM while the time-variations of the (unknown) BEM coefficients are likely much slower than those of the channel. We track the BEM coefficients via the exponentially-weighted recursive least-squares (RLS) algorithm, aided by symbol decisions from a decision-feedback equalizer (DFE). Such a scheme was recently presented in a conference paper by the authors [1]. In this paper we investigate selection of the forgetting factor in the RLS algorithm. We show that its selection depends upon how often the BEM coefficients are updated and we provide simple guidelines for its choice. Simulation examples demonstrate superior performance of the proposed decision-directed scheme over an existing subblock-wise channel tracking scheme.