N-user trellis coding for a class of multiple-access channels (Corresp.)

Trellis coding is investigated for a class of -user multiple-access channels. It is shown that -user trellis coding, in conjunction with Viterbi or sequential decoding, permits the multiple-access function to be combined with forward error correction. The distance and rate properties are analyzed for linear (convolutional) -user trellis codes, and the use of nonlinear -user trellis coding is discussed. A procedure is given for constructing -user convolutional-code -tuples with large free distance. Finally the error performance is analyzed, and coding gains of several decibels over uncoded time sharing are verified by simulation results.