이진 LDPC 부호를 위한 디더 신뢰 전파 알고리즘

Abstract

Low-density parity-check (LDPC) codes achieve the performance near to the Shannon limit by iterative decoding, representatively the sum-product algorithm. Post-processing algorithms are used for fulfilling the lower error rate. Almost of errors are occured by the code structure, just as cycle and trapping set, so almost of post-processing algorithms are construct to overcome the problem caused by these structure. But existing post-processing algorithms has problem in the view of complexity. So, in this paper, we pay attention to the random initial state (RIS) algorithm, which has not much of complexity. The composition of this thesis can be divided into two parts. Firstly, we survey the various post-processing algorithm and see the drawback of each of algorithms. Secondly, and mainly, we introduce the RSF and RIS algorithm and propose the modified RIS algorithm. This algorithm is using the reliabilities of each variable nodes to determine the unreliable bits. We adjust the unreliable bits only, and show this method can reduce the error rate.