PERFORMANCE BOUNDS FOR MLSE EQUALIZATION AND DECODING WITH REPEAT REQUEST FOR FADING DISPERSIVE CHANNELS

Upper bounds on the bit error probability and repeat request probabili ty. and lower bounds on the throughput are derived for a Hybrid-ARQ sc heme that employs trellis-coded modulation on a fading dispersive chan nel. The receiver employs a modified Viterbi algorithm to perform join t maximum likelihood sequence estimation (MLSE) equalization and decod ing. Retransmissions are generated by using the approach suggested by Yamamoto and Itoh. The analytical bounds are extended to trellis-coded modulation on fading dispersive channels with code combining. Compari son of the analytical bounds with simulation results shows that the an alytical bounds are quite loose when diversity reception is not employ ed. However, no other analytical bounds exist in the literature for th e trellis-coded Hybrid ARQ system studied in this paper. Therefore, th e results presented in this paper can provide the basis for comparison with more sophisticated analytical bounds that may be derived in the future.