A New Improved Symbol Mapper/8-Ary Constellation for BICM-ID

Slimane Benmahmoud, Ali Djebbari

Telecommunications and Digital Signal Processing Laboratory, Djillali Liabes University, Sidi Bel-Abbes, Algeria.
Telecommunications and Digital Signal Processing Laboratory, Djillali Liabes University, Sidi Bel-Abbes, Algeria; Department of Electronics Engineering, M’sila University, M’sila, Algeria.

DOI: 10.4236/wet.2013.42010                

Abstract

This contribution proposes a new combination symbol mapper/8-ary constellation, which is a joint optimization of an 8-ary signal constellation and its symbol mapping operation, to improve the performance of Bit Interleaved Coded Modulation with Iterative Decoding (BICM-ID). The basic idea was to use the so called (1,7) constellation (which is a capacitive efficient constellation) instead of the conventional 8-PSK constellation and to choose the most suitable mapping for it. A comparative study between the combinations most suitable mapping/(1,7) constellation and SSP mapping/conventional 8-PSK constellation has been carried out. Simulation results showed that the 1^st combination significantly outperforms the 2^nd combination and with only 4 iterations, it gives better performance than the 2^nd combination with 8 iterations. A gain of 4 dB is given by iteration 4 of the 1^st combination compared to iteration 8 of the 2^nd combination at a BER level equal to 10^-5, and it (iteration 4 of the 1^st combination) can attain a BER equal to 10^-7 for, only, a SNR = 5.6 dB.

Keywords

Bit Interleaved Coded Modulation; BICM; Iterative Decoding/Processing; Log-Likelihood Ratios (LLRs); 8PSK Constellation; Signal Mappings; Constellation Labeling Maps; Extrinsic Information; BCJR Algorithm

Conflicts of Interest

The authors declare no conflicts of interest.

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