A DFE coefficient placement algorithm for underwater digital acoustic communications

We describe and evaluate an algorithm for determining decision-feedback equalizer (DFE) coefficient placements from an estimated channel response. Efficient tap placement is desirable to minimize equalizer computation in multichannel, underwater acoustic environments due to long, potentially sparse channel responses lasting hundreds of symbols or more. Although our algorithm relies on heuristics to simplify the placement search, it is based on taking advantage of the interaction between the minimum mean-squared error (MMSE) optimal feedforward and feedback filters, rather than optimizing over each separately. Tests of the automated routine on two diverse sets of data gathered from an at-sea experiment of an underwater acoustic communication system demonstrate the algorithm's ability to provide complete automation of the tap placement process while maintaining performance.