IMPROVED TRELLIS-CODING FOR PARTIAL-RESPONSE CHANNELS

New code design methods and Viterbi detector architectures are present ed for high-rate trellis-coded partial-response (TCPR) systems. The me thods, which extend the matched-spectral-null (MSN) coding technique, use novel code constraints and time-varying detector trellis structure s to reduce path memory requirements by as much as a factor of two, re lative to previously reported codes, while retaining the other attract ive features of MSN codes. The design methods and corresponding time-v arying trellis structures are illustrated with several examples.