Study On The Coded Modulation Technology Of QC-LDPC Codes Based On The Algebraic Construction

With the rapid developments of Internet technology and communication technology, which requires the system has higher spectrum efficiency, how to transmit more information with the limited bandwidth becomes a very practical problem, Coded Modulation(CM) technique is one of the effective methods to solve this problem, and the CM technology can transmit more information without additional bandwidth. As a representative of CM technology, Bit-Interleaved Coded Modulation with Iterative Decoding(BICM-ID) technique has received the widespread attention.Quasi-Cyclic Low Density Parity Check(QC-LDPC) codes constructed by algebraic method are regarded as a good coding scheme, the development is very huge in the future communication technology. Therefore, the principles of QC-LDPC codes in coding and decoding, as well as the constellation mapping scheme of BICM-ID system are discussed. The main achievements in this dissertation are as follows:1. Deeply analyzed the structure of extended Irregular Repeat Accumulate Low Density Parity Check(eIRA-LDPC) codes, and on the base of it, a novel construction method of the extended Irregular Repeat Accumulate Quasi-Cyclic Low Density Parity Check(eIRA-QC-LDPC) code, based on finite field, is proposed, then a novel-eIRA-QC-LDPC(4599,4307) code is constructed by applying the proposed construction method, which code rate is 93.7 percent, then analyze the code performance from bit error rate and Extrinsic Information Transfer.2. Systematically analyzed the structure of QC-LDPC-BICM-ID system, and mainly studied the constellation mapping design principles of BICM-ID system and the characteristics of traditional mapping scheme. This paper proposes a novel double-ring structure, and gives two different constellation mapping schemes under the structure.3. The novel-eIRA-QC-LDPC(4599,4307) code as the component code is applied to the QC-LDPC-BICM-ID system, and adopting 8PSK mapping scheme, a novel LDPC-BICM-ID system is proposed after comprehensive, then simulate the system performance from channel capacity, bit error rate and Extrinsic Information Transfer, and the simulation results show the new coded modulation scheme with spectral efficiency and superior bit error performance.