Turbo Code Codec And Dsp Implementation

Noises and distortions are involved in digital communication system inevitably, so error control coding must be included in the system. C.E.Shannon published his thesis 'A mathematical theory of communication' in 1948, which accelerated the development of error control coding greatly. Turbo code is considered one of the most exciting and potentially important developments in coding theory in many years. Because of its characteristic of approaching the Shannon bound, Turbo codes have been recommended in 3GPP regulations.This paper is separated several parts: encoder, decoder, interleaver and its implementation on DSP. The main works include:The main researches are the constructions of encoder and the stimulation the encoder using Matlab software. The main factors to influence performance of Turbo code are analysed, which include puncture matrix, recursive systematic convolutional (RSC) code, encoder tail bits, etc. And the stimulation results are given.Decode constructions of Turbo code are researched, and stimulate results are given.. Because decoding algorithm is one of an important factor to performance, the Maximum A Posteriori (MAP) decoding algorithm and its simplification Log-MAP and MAX-Log-MAP algorithm are researched. Furthermore, their performances are stimulated using Matlab software with Additive white Gaussian noise (AWGN) and Rayleigh channel and the results show that performances of MAP algorithm and the Log-MAP algorithm are resemble, performance of MAX-Log-MAP algorithm is lower than the two others because of the loss of soft informations.The interleaver is also one of the important factor to Turbo code. S-interleaver has better performance than other interleavers. Interleaver length does not be neglected, and the longer length, the lower error code rate.Based on performance and complexity, a digital communication system is carried out at the platform of ADSP-TS101S, which includes Turbo code and the algorithm used MAX-Log-MAP algorithm.