Turbo Decoding Simulation And Implementation Based On DVB-T

DVB-T (Digital Video Broadcast-Terrestrial) is the European terrestrialtransmission standard. The wireless channel interference and fading channel codec has adirect impact on the channel codec performance of the system. Therefore, finding agood coding scheme becomes the focus of the present study. Turbo code is used as anovel channel coding scheme. The error correction performance approaches Shannonlimit. Once generated, it becaomes the focus of research of information and codingtheory.Dissertation mainly studied structure and complementation of Turbo, meanwhile,researched the related algorithms and design of interleavers. Then introduced Turbo intoDVB-T system and made DSP verifications. The main research and innovation are asfollows:Firstly, the dissertation elaborated the theory of Turbo coding. Deeply studyingBCJR, MAP, Log-MAP, SOVA algorithms, results showed that decoding algorithms, thenumber of iterations, the redundancy of symbols and interleaving depth were importantfactors to Turbo codes. To reach the purpose of improving the performance andreducing the complexity, taylor and a new algorithm based on a segment approximationmethod were deduced. It was the improvement. Simulation results showed that theperformance of second-order approximation algorithm and the Log-MAP algorithm wasvery close. It reduced the decoding complexity and improved the efficiency of the codes,easily carried out in hardware.Secondly, the station of interleaver in Turbo coding and designs of interleaverswere discussed. After analyzing their characteristics, the design principles of TurboCode were summed up. Learned the limitations of S-random interleaver, S symmetricrandom interleaver was advanced. From the simulation results, when the interleavingdepth was large, the time and complexity of new random program generation was betterthan the general S-random interleaver.Thirdly, dissertation introduced the implementation mechanism and basicprinciples of the DVB-T system receiving end. For16QAM modulation system, deduced the algorithm of the soft information. To improve the performance of DVB-Tsystem, the original system code was replaced by Turbo code. Simulations indicatedthat the error correction performance of the DVB-T system increased significantly afterthe introduction of Turbo codes.Finally, dissertation researched the embedded TCP module of TI’s TMS320C6416chip. Then it was applied to accomplish Turbo codec. After comprehensiveconsideration of performance and complexities, Turbo Decoding DSP design wasaccomplished by CCS software. Verification showed that design of the Turbo code had agood performance and could be operated stably. By comparison, embedded TCP modulehad better performance, but Turbo designed by CCS were more flexible and could beapplied to varieties of occasions.