Research On Lossy Protograph LDPC Coding Over GF(2)

With the development of Mobile Internet and Internet of Things,a mass of data needs to be transmitted or stored quickly in various fields.In order to improve the efficiency of data transmission and reduce the storage space,it is necessary to use data compression technology.The lossy compression technology can transmit information at the lowest possible bit rate while ensuring the reliability of information as far as possible,which is of great significance to the development of information system.Quantization,as the main method of lossy compression,is the key to lossy source coding.Lossy source coding is a dual problem of channel coding,and due to the LDPC codes commonly used in channel coding,they are well-suited to quantization problems.After years of research,the lossy source coding scheme based on LDPC codes over GF(q)can achieve excellent rate-distortion performance,but the performance of the binary scheme still has a big gap with rate-distortion capacity limit.In view of the high system complexity of multi-ldpc code lossy compression,which is difficult to implement in hardware,and the problem that the code structure of binary domain cannot adapt to lossy compression coding,this paper proposes to use the original LDPC(p-ldpc)code as the quantized code book.In the vector quantization algorithm part,the general RBP(rc Propagation)algorithm of BP algorithm is used to construct the lossless compression model.Simulation results show that the asymptotic rate distortion function can be obtained.Then by using different LDPC code structures of the original pattern for simulation,we can get better rate distortion effect.In order to further optimize the rate-distortion performance of the system and improve the convergence speed of the algorithm without increasing the complexity of the system,this paper optimizes the vector quantization algorithm,and proposed an improved lossy source coding scheme based on the protogrph LDPC codes.Firstly,on account of the RBP algorithm is the general form of the BP algorithm,the RBP algorithm can be optimized like the BP algorithm.According to the idea of BP group shuffled scheduling algorithm,a Shuffled RBP algorithm is proposed as the quantization algorithm in the lossy source coding.In addition,AR4JA codes are used as the codebook to further explore the gain brought by the code structures design.Finally,the simulation results show that the rate-distortion performance of the improved system has been improved obviously over GF(2),and the gap between the improved system and the GF(q)system is not large when the asymptotic rate-distortion function is achieved.At the same time,compared with the reference group,the average convergence times of the quantization algorithm significantly decreased,which dramatically improved the convergence speed of the system...