Terrestrial radio links with sparsely distributed multipath delays can be represented by a tapped-delay line with a few significant tap coefficients. This letter presents criteria and performance of identification methods that determine channel taps with significant power. In particular, a tap identification method derived from the maximum-likelihood criterion and its closed form error probabilities are presented. Performance improvement over a previously reported scheme is quantified using the derived error probabilities.

This paper proposes and investigates a tap selectable Viterbi equalizer for mobile radio communications. When the multipath channel is modeled by a tapped delay line only, the taps which may seriously affect the data sequence estimation are selected and used to calculate the trellis metric in the Viterbi algorithm. The proposed equalization algorithm can reduce the number of path metric calculations and the number of path selections in the Viterbi algorithm. Moreover, we propose an extended equalizer which has antenna diversity. This equalizer calculates the path metric using the antenna outputs and results of channel estimators. Computer simulation is used to evaluate the BER performance of the proposed equalizer in a multipath radio channel.