Symbol mapping diversity in iterative decoding/demodulation of ARQ systems
نویسندگان
چکیده
This paper presents a simple, yet effective method of enhancing the inherent diversity among packet retransmissions in digital communication systems that employ high-order modulations such as M -PSK and M -QAM through frequency-selective channels. Diversity is enhanced by uniquely redefining the bitto-symbol mapping for each retransmission. Finding the optimal mappings leads to iterative solutions of the Quadratic Assignment Problem. More importantly, jointly equalizing transmissions with different mappings only requires a marginal increase in complexity, while providing substantial gains in bit error rates (BER) and frame error rates (FER).
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