Multitrellis decomposition of the Viterbi algorithm for multipath channels

A reduced complexity Viterbi algorithm for use as sequence estimator for linear intersymbol interference channels with coarsely located coefficients is presented. As an example, for an 8-phase-shift keying (PSK) modulation scheme and assuming a multipath channel of length 16 and only three nonzero coefficients, the proposed algorithm reduces the computational complexity by more than three orders of magnitude. In practice, the impulse response of a real life multipath channel can have more than three non-zero coefficients. From the estimated channel impulse response, the desired impulse response, formed of the three largest coefficients of the channel impulse response, is derived. A linear equalizer is used to filter the received sequence and shape the channel impulse response to the desired impulse response. Results are presented for a particular HF channel