Design of unpunctured turbo trellis-coded modulation

In this paper, the design of newly introduced turbo encoding scheme called ‘Unpunctured Turbo Trellis-Coded Modulation’ (UTTCM) is exposed. The performance improvement of this encoding scheme is obtained by setting a design criterion for each of its components namely: the search rules of best constituent encoders’ generator polynomials, the constellation and the associated mapping. Simulation results show that the optimized UTTCM outperforms TTCM and PCTCM for all considered spectral efficiencies, and presents competitive error floors. As examples, for a spectral efficiency of 3 bits/symbol (bps), UTTCM with 8 decoding iterations outperforms TTCM by 0.05 dB at BER = 10−4; and for a spectral efficiency of 4 bps and 6 decoding iterations, UTTCM outperforms Fragouli's PCTCM by 0.07 dB at BER = 10−5.