Design And Construction Of QC-LDPC Code In High Speed Optical Communication

With the development of the ages and the progress of science and technology,the era of big data has arrived.The rapid development of technologies such as cloud computing,4K HD video and VR has put forward higher requirements on network bandwidth and data traffic.Although the rapid development of high-speed optical transmission systems to meet the needs of the network,but the optical fiber dispersion,nonlinear effects seriously affect the optical transmission system in rate and transmission distance.As the key factor to solve the physical damage,ensure the system reliability and enhance the transmission distance,FEC becomes a research hotspot in optical transmission systems.Quasi-cyclic low-density parity-check codes(QC-LDPCs)are widely studied in the field of channel coding and optical communication because of their high coding gain and parallel coding.This dissertation focuses on the design and construction of QC-LDPC codes in high-speed optical communication systems.The main works are as follows:1.Aiming at the girth that affects the performance of binary regular QC-LDPC codes,a heuristic search method for constructing large girth QC-LDPC codes was designed,which greatly accelerated the construction of large girth QC-LDPC codes.The simulation results show that compared with the existing large girth QC-LDPC construct method based on search,the time of proposed method is reduced to thousandth,and the code performance has not lost.2.Aiming at the factors that affect the performance of binary irregular QC-LDPC codes,such as the minimum column weight,the number of cycle and the degree distribution,an irregular QC-LDPC code construction method based on cycle distribution matrix is designed.,obtain the best QC-LDPC code with cycle distribution performance.The simulation results show that the proposed construction method can construct irregular QC-LDPC codes with different code rates with good error performance and low error floor.3.For the characteristics of non-binary QC-LDPC that has high coding gain and high complexity,a non-binary QC-LDPC method was proposed.The method combines finite geometry and masking matrix to construct high performance non-binary QC-LDPC code.The simulation results show that the constructed QC-LDPC codes of 4-ary,8-ary and 16-ary,the performance improve compared with the codes that constructed with finite geometry method.