Equalization of Sparse Intersymbol-Interference Channels Revisited

• Format: Article
• Language: English
• Published: SpringerOpen 2006-01-01
• Series: EURASIP Journal on Wireless Communications and Networking
• Online Access: http://www.hindawi.com/GetArticle.aspx?doi=10.1155/WCN/2006/29075

<p>Sparse intersymbol-interference (ISI) channels are encountered in a variety of communication systems, especially in high-data-rate systems. These channels have a large memory length, but only a small number of significant channel coefficients. In this paper, equalization of sparse ISI channels is revisited with focus on trellis-based techniques. Due to the large channel memory length, the complexity of maximum-likelihood sequence estimation by means of the Viterbi algorithm is normally prohibitive. In the first part of the paper, a unified framework based on factor graphs is presented for complexity reduction without loss of optimality. In this new context, two known reduced-complexity trellis-based techniques are recapitulated. In the second part of the paper a simple alternative approach is investigated to tackle general sparse ISI channels. It is shown that the use of a linear filter at the receiver renders the application of standard reduced-state trellis-based equalization techniques feasible without significant loss of optimality.</p>