Serial concatenated trellis coded modulation with inner rate-1 accumulate code

We propose a serial concatenated trellis coded modulation system using one or more inner accumulate code(s) and a Gray-labeled signal constellation. We show the existence of a threshold, such that if the signal-to-noise ratio (SNR) exceeds this threshold, the bit error probability goes to zero as the blocklength goes to infinity. Tight numerical values for the thresholds for an iterative decoder are found by density evolution. Despite the simple inner code, the simulated performance in AWGN and Rayleigh fading is comparable to that of more complex systems suggested in the literature