Decoding of trellis-encoded signals in the presence of intersymbol interference and noise

• Published in: IEEE transactions on communications Vol. 37; no. 7; pp. 669 - 676
• Main Authors: Chevillat, P.R., Eleftheriou, E.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.1989; Institute of Electrical and Electronics Engineers
• Subjects: Additive white noise; Applied sciences; AWGN; Decision feedback equalizers; Decoding; Exact sciences and technology; Filters; Gaussian noise; Information, signal and communications theory; Intersymbol interference; Modulation coding; Phase distortion; Telecommunications and information theory; Viterbi algorithm; Noise; Coding; Interference
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/26.31158

A novel receiver for data-transmission systems using trellis-coded modulation is investigated. It comprises a whitened-matched filter and a trellis decoder which combines the previously separated functions of equalization and trellis-coded modulation (TCM) decoding. TCM encoder, transmission channel, and whitened-matched filter are modeled by a single finite-state machine with combined intersymbol interference and code states. Using ISI-state truncation techniques and the set-partitioning principles inherent in TCM, a systematic method is then developed for reducing the state complexity of the corresponding ISI and code trellis. A modified branch metric is used for canceling those ISI terms which are not represented by the trellis states. The approach leads to a family of Viterbi decoders which offer a tradeoff between decoding complexity and performance. An adaptive version of the proposed receiver is discussed, and an efficient structure for reduced-state decoding is given. Simulation results are presented for channels with severe amplitude and phase distortion. It is shown that the proposed receiver achieves a significant gain in noise margin over a conventional receiver which uses separate linear equalization and TCM decoding.< >