Research Of LDPC Code For High Density Optical Disk Storage System

Low-Density Parity-check Codes (LDPC), first developped by Gallager in 1962 are a class of linear block error-correcting codes, that can be defined by a very sparse parity-check matrix or the bipartite graph. They have very attractive properties: error performance approaching Shannon limits, easy description and implementation, convenient theoretical analysis and research, easily decoded in complete parallel ways and suitable for hardware implementation. LDPC codes have gained increasingly consideration of researchers with their excellent error performance, simple description and very good application foreground. LDPC codes have become another focus following Turbo codes in error-correcting fields. In recent years, some research branch proposed some ideas for using LDPC codes in high-density optical storage system, and carried out some simulations and tests.The results show that LDPC codes are a class of good performance code and very suitable for high-speed data transmission systems. However, as the Run-Length-Limited modulation codes (RLL) are used in optical storage systems, suitable solution must be provided for the collision between LDPC and RLL. Besides, in view of the growth of researches of high-density optical storage, design high bit-rate and good performance LDPC codes becomes imperative problem to be solved.In order to using LDPC codes in Next-Generation Versatile Disc (NVD), based on NVD's performance, a new channel encoding process and application scheme has been developped: using Q-matrix based LDPC encoding, researching in different coding parameters; simulating the NVD encoding scheme after using LDPC code under the MATLAB tools and analysis the simulation results.The results show that, the channel's original error rate can be further decreases, by adopting LDPC code, decreasing the error rate after error correcting for the fault-tolerant requirement of NVD system, and the redundancy increased limited.