Sequential Decoding of Trellis Codes

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Trellis-coded modulation (TCM) has proved to be very effective as a modulation technique for bandwidth-efficient communication. Higher data rates over a given channel are obtainable using this technique. Typically, the decoders for this modulation format are Viterbi decoders, which perform a maximum-likelihood sequence estimation upon soft-decision data extracted from the received signal. The complexity of the Viterbi decoders grows exponentially with code constraint length, thus limiting practical operation to moderate coding gains and decoding speeds. The sequential decoding technique gives a performance which is independent of code constraint length thereby permitting the use of longer codes to obtain a greater coding gain. This project is concerned with: 1. The selection of an appropriate sequential decoding algorithm for use with trellis-coed modulation. 2. The performance evaluation of sequential decoding, using both analytical and simulation techniques when used with trellis-coded modulation. 3. The construction of good long-constraint-length trellis codes for use with sequential decoding.