Performance of 4-State Asymmetric 8-PSK TCM-STBC in Fast Fading Channels
ABSTRACT We use an asymmetric 8-PSK signal sets in the 4-state rate 2/3 trellis-coded modulation concatenated with space-time block coding (TCM-STBC) scheme for fast fading channels, and show performance gain over TCM-STBC scheme with symmetric 8-PSK constellations. The performance gain is due to an increase in the minimum product-sum distance and free distance of trellis code compared to that of the symmetric 8-PSK signal sets. Simulation for fast Rayleigh fading channels shows that the proposed asymmetric 8-PSK TCM-STBC scheme outperforms symmetric scheme by about 0.3 dB at frame error rate of 10-3.
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ABSTRACT: This letter studies the optimization of asymmetric constellations for trellis-coded modulation (TCM). Unlike the conventional criterion of maximizing the free Euclidean distance, the criterion here is to minimize the bit error rate (BER) of TCM systems. The letter presents an easy way to derive the BER upper bound for any TCM codes, and proposes the method for designing optimum asymmetric constellations by minimizing the bound. The given method can be applied to TCM systems with arbitrary state numbers. Numerical results verify that all the codes designed by the proposed method achieve better BER performance than symmetric ones.IEEE Communications Letters 08/2009; · 1.46 Impact Factor