Design Of Decoder For Quasi-cyclic Low-Density Parity-Check Codes And Its FPGA Implementation

As the development of communications technology, people are increasinglydemanding to access to information at anytime wherever they are. As a portablecommunication tools, phone play an important role in transmitting information.Phone-based mobile TV carry a wide range of information, it will get a greatdevelopment in the future. As a national standard, Terrestrial Mobile MultimediaBroadcasting will become a hot spot.This paper describes the design and implementation of the decoder andsoft-output demapper in the T-MMB. Encoding and decoding technology withexcellent performance is the guarantee of good communication performance.T-MMBtakes Quasi-cyclic low-density parity-check codes as its error correction coding.Thecode has good performance and structure which is easy to be implemented withhardware. It has features similar to Low density parity check code, and can learn fromits more mature decoding algorithms. LDPC code has a variety of decodingalgorithms. Based on the studies on all these decoding algorithms, it determine s totake the min-sum decoding algorithm as the decoding algorithm to implement onXilinx’s FPGA.First of all, it introduces the relevant background of T-MMB and the basics ofLDPC code. Second, it studies several soft-output demapper algorithms and decodingalgorithms, compares these algorithms in terms of performance and complexity, anddetermine s to take the max algorithm and the min-sum decoding algorithm toimplement. It sets up simulation model of the whole system in Matlab to obtainperformance to provide theoretical basis for the subsequent design. Finally, it givesthe design of the decoder and each of its sub-modules, such as check node unit,variable node unit and soft-output demapper unit. It also designs a new method ofstoring information to reduce the waste of RAM resources.The result shows that the decoder can meets the system’s requirements on thetiming, resource usage and performance and can be used as the decoder for thestandard. The design has a certain reference value on the other QC_LDPC decoderdesign.