Pragmatic vs. TCM codes. A performance comparison for severely band-limited nonlinear satellite channel

The performances of Ungerboeck trellis-coded-modulation (TCM) codes on band-limited nonlinear satellite channels and of the pragmatic codes, which are standard convolution 1/2-rate codes mapped into M -ary phase-shift-keyed (M-PSK) signals, are reviewed. Using a computer simulation, the performance of a 16-state, 2/3-rate encoder of 8-PSK Ungerboeck and pragmatic codes estimated for band-limited nonlinear satellite channel is presented, demonstrating the robustness of both Ungerboeck and pragmatic codes for severely band-limited nonlinear satellite channels. It is shown that when the band-limitation is too severe, major intersymbol interference occurs, and a coding gain of 0.8 dB and 1.1 dB will be lost for Ungerboeck and pragmatic codes, respectively. When the bandwidth-time product is 1.2, the performance of pragmatic codes is shown to be within 0.8 dB of that of Ungerboeck codes showing that the pragmatic codes are attractive for severely band-limited nonlinear satellite channels