Structure Design Of SC-LDPC Code On Burst Erasure Channel

The Low-Density Parity-Check(LDPC) code proposed by Gallager, well known for its near Shannon performance, has been widely used in communication fields.It is widely accepted that the long pseudo-random LDPC code performs well on memoryless channels. However, the research interests have focused on the transmission of LDPC code on channel with memory in recent years. Studies have shown that structured LDPC code is a reasonable choice for channel with memory. Due to the simple structure and the similarity with many practical communication systems, the Binary burst Erasure Channel(Bu EC) is selected as the starting point of the application of LDPC code on channel with memory.Based on uncoupled LDPC code, we can get Spatially-Coupled LDPC(SC-LDPC) code by the edge-spreading approach. As is known to all that SC-LDPC code has Capacity-approaching performance on all Binary Memoryless Symmetric(BMS) channels. However, Ohashi pointed out that SC-LDPC code lacks immunity against burst erasures compared to uncoupled LDPC code.A good erasure correcting code should not only deal with memoryless random erasures effectively, but also have strong capability of correcting burst erasures. Therefore, because of SC-LDPC code's excellent structure and Bu EC's great application prospect, it is significant to design new spatially-coupled structures which can greatly improve the burst erasure correction performance. This thesis mainly carries out the design of new SC-LDPC code on Bu EC.Firstly, we focus on the protograph of SC-LDPC code whose degree distribution likes(k~?,2k~?), and have designed a kind of asymmetric SC-LDPC code whose upper coupling width is different from the lower one by using the method of continuously increasing the upper coupling width of the coupling chain while keeping the lower coupling width unchanged. The asymmetric SC-LDPC code we proposed could not only solve the problem that SC-LDPC code suffers serious degradation in performance on Bu EC, but also have the advantage of the corresponding structure's Belief Propagation(BP) iterative decoding performance is getting better and better with the increasing of the upper coupling width. The consistency of the simulation results, the analysis of Density Evolution(DE) and the general expressions proves strongly that the asymmetric SC-LDPC code we constructed has strong robustness.Secondly, we introduce and analyze the principle and procedure of the band splitting permutation method, whose effectiveness of improving the performance of SC-LDPC code on Bu EC is verified by simulation and theoretical analysis.Finally, the general expressions which can characterize the burst erasure correcting performance of two different asymmetric SC-LDPC codes respectively are obtained by statistics, analysis and summary, explaining the reason why the burst erasure immunity of the first asymmetric SC-LDPC code is stronger than that of the second asymmetric SC-LDPC code though their transformation modes are symmetrical.