Simulation and Performance Comparison of BP and NMSA Algorithm for QC-LDPC Codes under CCSDS Standards in BPSK-Modulated AWGN Channels

Low-Density Parity-Check (LDPC) codes are essential for error correction in space communications, particularly in CCSDS implementations. Space communication channels face interference challenges due to extreme distances and signal attenuation. While Belief Propagation (BP) and Normalized Min-Sum Algorithm (NMSA) are widely used decoding techniques, quantitative comparisons for short-length QC-LDPC codes remain insufficient. This paper addresses this gap through systematic evaluation. This article implemented QC-LDPC encoding structures per CCSDS standards and conducted MATLAB simulations using BPSK modulation over AWGN channels. Simulations compared 1/2-rate codes across different lengths which including 320, 640, 1280 bits, and analyzed performance across rates (1/2, 2/3, 4/5) with fixed information length. Results show performance improves logarithmically with code length. BP outperforms NMSA by 0.2-0.3dB at low SNRs, while differences narrow at moderate SNRs. At high SNRs, NMSA occasionally surpasses BP due to better numerical stability. These findings provide reference data for spacecraft communication system designers facing power and computational constraints.