Implementation Of Turbo Decoder Based On TMS320C6713DSP

The emergence of Turbo codes is a milestone in the history of channel coding. Asa high-performance channel coding, Turbo codes have brought a major breakthroughin the research of error correction code, because of its good characteristics near theShannon limit. With the deepening of the research and the increasingly perfectperformance, Turbo codes have been widely applied to multimedia communications,satellite communications, deep space communications and other actual fields, andbecome a channel error correction code alternative scheme of3G/4G mobilecommunication system.The related researches of Turbo codes mainly concentrate in low bit rate (1/2or1/3rate) Turbo codes, so high rate (2/3,3/4and4/5) Turbo codes designed by using thepuncturing technique are simulated and the performance are analyzed. The common(MAP) decoding algorithms include MAP, Log-MAP and Max-Log-MAP algorithm.On the basis of the MATLAB simulation and performance comparison of these threedecoding algorithms, this thesis selects Max-Log-MAP algorithm as the decodingalgorithm because it has good performance and acceptable complexity and studies therealization of Turbo decoding functions based on TMS320C6713DSP platform.Firstly, the thesis introduces the development of Turbo codes and the structure andprinciple of Turbo encoder, mainly including the component encoder, interleaver,puncturing device and so on. A large number of simulations are made on severaldifferent high bit rate (2/3,3/4and4/5) Turbo codes, and the influence of code rate onTurbo codes performance is analyzed. Then the thesis describes the principle andstructure of Turbo decoder, detailed introduces the MAP, Log-MAP andMax-Log-MAP algorithm, and simulates these three algorithms under different coderate. Finally, the optimization, adjustment and exception handling problems ofMax-Log-MAP algorithm in DSP programming process are introduced. The functionof Turbo codes decoding based on TI Company’s TMS320C6713DSP is realized usingassembly language. Simultaneously, the validity of the DSP assemble languageprogram results is demonstrated. Turbo codes Max-Log-MAP decoder achieved byDSP assembly language designed in this thesis can complete Turbo code decoding withlow complexity and processing delay, thus has certain actual application value.