The Research Of Turbo Decoding Algorithm And Interleaver

Shannon capacity limit has been a goal that people always seek, Turbo codes introduced by C. Berrou etal in 1993, the full name is parallel concatenation of recursive systematic convolutional codes, can be able to get close to the performance of Shannon capacity limit, and thus the research about Turbo codes become the focus of the research in the recent year.In this paper two problems mainly are studies, one is the decoding algorithm of Turbo codes, the other is the design of the interleaver which is one of the components of the Turbo decoder and encoder. In the first place, the history of the Turbo code is introduced, the current research work for the Turbo codes are also summarized, and the shortcomings are put out. In the next place some of the theoretical of Turbo codes are described, such as coding theory of convolution code. On this basis, the principle and effect of the Turbo encoder and decoder are introduced. The next section mainly focuses on the research about the decoding algorithm of the Turbo codes, related MAP algorithm and SOVA algorithm(soft output Viterbi algorithm). In this section some work about improving decoding algorithm has been done, for example, to improve the performance of MAP algorithm, sub-function is used in the MAP algorithm instead of the correction function which is used in the MAP algorithm, using slicing technology reduce coding delay. In addition, the effect of factors which affect Turbo codes is analyzed, the performance of Turbo codes in the different parameters also has been simulated. In the end the theory of the interleaver is introduced. And the design method of the two interleavers has been studied, one is the best period interleaver, the other is the S random interleaver in which the new constrain condition is used. And the performance of the two interleavers which are referenced earlier also have been simulated.