Study on QC-LDPC Codes Based on BIBD for Optical Communication Systems

Based on the Balanced Incomplete Block Design(BIBD),a novel construction method of Quasi-Cyclic Low-Density Parity-Check(QC-LDPC) codes is further analyzed and researched.And the three QC-LDPC codes with the same code-rate and different code-length are constructed by applying the proposed method.The simulation analysis shows that under the condition of the same code-rate,the QC-LDPC code with the longer code-length has better error-correction performance.Simultaneously,at the condition of the bit error rate(BER) of 10-6 and the same code rate of 93.7%,the net coding gain(NCG) of the constructed BIBD-QC-LDPC(5392,5056) code is respectively 2.13 dB and 1.41 dB higher than that of the classic RS(255,239) code widely used in optical communication systems and that of the LDPC(32640,30592) code in ITU-T G.975.1.Therefore,the BIBD-QC-LDPC(5392,5056) code has much superior error-correction performance and is better suitable for high-speed long-haul optical communication systems.