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

摘要

The performances of Ungerboeck trellis-coded-modulation (TCM)codes on band-limited nonlinear satellite channels and of the pragmaticcodes, 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-rateencoder of 8-PSK Ungerboeck and pragmatic codes estimated forband-limited nonlinear satellite channel is presented, demonstrating therobustness of both Ungerboeck and pragmatic codes for severelyband-limited nonlinear satellite channels. It is shown that when theband-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 andpragmatic codes, respectively. When the bandwidth-time product is 1.2,the performance of pragmatic codes is shown to be within 0.8 dB of thatof Ungerboeck codes showing that the pragmatic codes are attractive forseverely band-limited nonlinear satellite channels