Rate-compatible QC-LDPC codes design based on EXIT chart analysis

This paper proposes a "column extension" design method for rate-compatible quasi-cyclic (QC) low-density parity-check (LDPC) codes, which can provide efficient multi-rate coding schemes for communication systems with flexible spectrum efficiency. The optimization of degree distributions among multiple code rates makes the designed QC-LDPC codes achieve excellent performance at each code rate, while the nested parity-check matrix structure of the designed codes facilitates the implementation of multi-rate encoder/decoder and offers the advantage of low-complexity. A comparison with the multi-rate LDPC codes in DVB-S2 specification is addressed. Extrinsic information transfer (EXIT) chart analysis predicts the superiorities of the optimized degree distributions in E_b/N₀ thresholds, and the bit error rate (BER) simulation results show that the designed codes perform 0.03-0.1 dB better than the DVB-S2 64K codes at each typical code rate, with even shorter code length.