Optimizing Spectral Efficiency with LDPC Coded MQAM for Next-Generation Communication Systems

DOI: https://doie.org/10.1121/Jbse.2024371116

PRASHANTHI H J, KABBALLI PRASHANTH, H J JAMBUKESH

Keywords:

Coded Modulation, MQAM, LDPC Codes, Spectral Efficiency, Wireless Communication, Gray Mapping, AWGN Channel, Rayleigh Fading Channel.

Abstract:

This paper presents a coded modulation scheme combining Multilevel Quadrature Amplitude Modulation (MQAM) with Low-Density Parity-Check (LDPC) codes for wireless communication systems, offering an efficient and pragmatic approach for bandwidth-efficient transmission. The proposed scheme utilizes a single encoder and decoder without requiring an interleaver, which simplifies the implementation compared to other coded modulation techniques such as Turbo-coded modulation. Due to the complexity of analytically evaluating LDPC-coded modulation, the system’s performance is assessed through extensive computer simulations. Results show that the LDPC-coded MQAM scheme with Gray mapping achieves performance close to the Shannon limit over the Additive White Gaussian Noise (AWGN) channel, using LDPC codes with a length of 2304 bits and a maximum of 30 decoding iterations. The system also performs well in flat uncorrelated Rayleigh fading channels, and its performance can be further enhanced by increasing the number of decoding iterations and code length. The proposed scheme demonstrates a significant improvement in spectral efficiency while maintaining robustness in various channel conditions.

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