Matching pursuit based decision-feedback equalizers

In this paper, equalization of channels with large delay spread but with few nonzero taps, such as those encountered in HDTV, are considered. Exploiting the sparse nature of the channel impulse response, we propose a decision feedback equalizer (DFE) which is based on a channel estimate obtained via a matching pursuit (MP) algorithm rather than the standard least squares (LS) channel estimate. It is shown that equalizers so designed result in a large performance gain. It is also shown that while truncation of the LS channel estimate to give a sparse channel estimate leads to some performance improvement, it falls well short of the MP-based DFE. In addition, an adaptive scheme which is intermediate in complexity between the LMS and RLS is presented for updating the sparse channel estimate in a time-varying environment. This adaptive algorithm outperforms the LMS.