Designing of Bit-Interleaved Serially Concatenated Block-Coded Modulation With Iterative Decoding System for Power-Limited Channels

In this paper, a Bit-Interleaved Serially Concatenated Block Coded Modulation with Iterative Decoding (BISCBCM-ID) system is proposed, employing a Serially Concatenated Block Code (SCBC) with an outer and an inner encoder, where the inner encoder is combined with modulation based on Bit Geometrically Uniform (BGU) mapping. The proposed system enhances error correction performance while maintaining comparable computational complexity, compared to previous systems using only a single block code. Unlike traditional modulation schemes, this approach replaces multi-level modulation with an inner coding structure combined with BPSK, which expands the mapping space, introduces modulation redundancy, and improves the average bit distance. Evaluations over the AWGN channel show at least a 1.15 dB gain over the previous BICM-ID with single-level modulation, without added complexity. These results, validated through theoretical analysis and simulations, show promise for the proposed BISCBCM-ID system, and can be further improved for practical implementation in power-limited and error-sensitive applications.