Studies On Low-Density Parity-Check Codes Encoding Algothrim

LDPC codes is the key technologies of the future broadband wireless communication to raise the communication quality and the data rate. This thesis mainly studies the implementation of the LDPC codes in the narrow band communication system. the narrow band communication system requires that the LDPC codes with the MSK modulation own the error bit rate BER<10^-5 in the condition of signal noise rate SNR=2dB. Based on the implementation background , the key research of the thesis is the scheme of the LDPC encoding.The main problem of LDPC implementation is the high complication of its coding. Therefore, the aim of LDPC research in this thesis is to make the coding complication lower through the improvement of coding scheme and the structure of parity-check matrix. Firstly, several kinds of coding scheme is studied, cyclic codes and quasi-cyclic codes encoding algorithm and iterate algorithm finish the encoding and decline the encoding complexity by taking advantage of the internal characteristics such as the lower triangle structure and quasi-cyclic structure, so the improvement algorithms of parity-check matrix that the thesis presents are in accordance with the thus two kinds of encoding algorithms.Then, detailed analysis of the structure of parity-check matrix is presented. the emphasis is on several kinds of typical constructed algorithms of parity-check matrix, and presents three kinds of improved constructed algorithms of parity-check matrix, which has strong ability of correct errors, simple encoding structure , and is easy to implement.Finally, based on the implementation background , in the light of the expect target of the practical communication system, by the simulation analysis on the constructed algorithms of parity-check matrix and the factors that affected the performance of LDPC codes ,the thesis presents a scheme of encoding of LDPC codes, and applies a reference to the hardware implementation.