GenAlg-Based Multi-Objective Optimization of LDPC Codes for Multi-Level Coded Modulation

Yidi Zhang

doi:10.1109/tcomm.2026.3714301

GenAlg-Based Multi-Objective Optimization of LDPC Codes for Multi-Level Coded Modulation

2026-01-01

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DOI：10.1109/tcomm.2026.3714301

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This paper proposes a multi-stage multi-objective optimization framework based on a genetic algorithm for constructing rate-compatible low-density parity-check (LDPC) codes tailored for multi-level coded modulation (MLCM) schemes. The methodology establishes a hierarchical rate-compatible construction through successive rate-specific optimization stages, each employing a weighted modulation-aware fitness function according to the target operating regime. This enables optimization for specific modulation orders and code rates while maintaining rate compatibility among the LDPC base matrices through a freezing-inheritance rule. The fitness evaluation is guided by an extended protograph-based extrinsic information transfer (PEXIT) analysis for MLCM schemes, which enables computationally efficient genetic optimization without relying on exhaustive Monte Carlo simulations during the search process. To mitigate the tendency of threshold-based optimization to favor overly light column connections, decoding performance for finite block lengths is further evaluated through decoding-assisted feasibility checks, to verify the consistency between PEXIT threshold and practical decoding performance. Simulation results show that the optimized MLCM schemes with LDPC-coded least significant bit streams significantly outperform conventional LDPC-coded bit-interleaved coded modulation schemes across different code rates and modulation orders in the 5G New Radio standard. The proposed framework enables seamless rate-modulation adaptation for achieving highly spectrally efficient transmission, making it well suited for next-generation wireless communication systems.

Keywords:

Parity check codes

Optimization

Codes

Modulation

Matrices

Labeling

5G mobile communication

Decoding

Quadrature amplitude modulation

Signal to noise ratio

Multi-level coded modulation

low-density parity-check codes

high-order quadrature amplitude modulation

protograph-based extrinsic information transfer analysis

GenAlg-Based Multi-Objective Optimization of LDPC Codes for Multi-Level Coded Modulation

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