A fast algorithm for single block finite alphabet based channel identification

Blind channel identification techniques in a communication system usually exploit a known property of the source symbols such as a statistical or finite alphabet property. Recently, a purely algebraic approach that relies on guard intervals (sequences of zeros equal or longer in length than the channel memory) inserted between transmitted blocks has been considered. It was proved that only a single received block suffices for recovering the finite alphabet source and identifying the channel. This paper proposes a fast algorithm that achieves this theoretical limit, and when more blocks are used it achieves better performance in the presence of noise. The algorithm is based on a simple approximation which holds exactly in the noise free case. Numerical examples illustrate the advantages of the proposed algorithm.