Comparative Studies On Performance Of Irregular Concatenated Tree Codes And Repeat Accumulated Codes

Concatenated Tree (CT) codes and Repeat Accumulated (RA) codes are both a class of capacity approaching error- correcting codes. They combine many advantages of LDPC and Turbo codes.For not long code lengths, CT codes can outperform LDPC codes. CT codes are decodable by the belief-propagation algorithm. They combine many advantages of LDPC and Turbo codes, such as low decoding cost, fast convergence speed, and good performance.RA codes is one of Turbo-Like Codes, simple but very important. The complexity of decoding is low, and the performance is similar to CT codes. In this paper, the main results and contents are as follows.1. The structure of CT codes and factor graph were introduced briefly. At the same time the affection of some parameters were analyzed. Then simulated CT codes, and compared with Turbo codes and LDPC codes.2. The structure of RA codes, encoder and factor graph were introduced briefly. Some different decode algorithms and the complexity were analyzed. Then simulated RA codes, and compared with CT codes.3. The encoding & decoding principle of irregular CT codes and RA codes is presented, we analyzed the factor graph, and then simulation results are given. Besides, we concluded the performance of irregular codes.CT codes and RA codes are both new codes. Lots of studies need to be done including encoding and decoding algorithm, performance of irregular codes in different channel models such as all kinds of fading channels. Combining the advantages of regular and irregular codes to construct the irregular codes with near-regular structure.