Reduced-State Sequence Detection of Multilevel Partial-Response Signals

This paper is concerned with the problem of designing reduced-complexity Viterbi decoders for the transmission of digital data over intersymbol-interference channels. First, optimal state-grouping for constructing reduced-state trellises is presented and illustrative examples are given for multilevel transmission over partial-response channels of the type 1 ±D″, (1+D)², (1+D)²(l-D), and (1+D)³(1-D). Then, the quaternary 1 D type partial-response channel is considered in more detail and a difference-metric algorithm employing state-reduction is derived and shown to result in a simple decoding scheme. © 1992 IEEE