In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC component code. Firstly, the sub-channel capacities of MLCM systems is analyzed and discussed, based on which the optimal component code rate can be obtained. Secondly, an extrinsic information transfer chart based two-stage searching algorithm is proposed to find the good irregular QC-LDPC code ensembles with optimal component code rates for their corresponding sub-channels. Finally, by constructing the irregular QC-LDPC component codes from the designed ensembles with the aim of possibly enlarging the girth and reducing the number of the shortest cycles, the designed irregular QC-LDPC code based 16QAM and 64QAM MLCM systems can achieve 0.4 dB and 1.2 dB net coding gain, respectively, compared with the recently proposed regular QC-LDPC code based 16QAM and 64QAM MLCM systems.
National Natural Science Foundation of China(No.61571061).
Liqian Wang,was born in Songyuan City,Jilin Province, China in 1980. She received the B.S. degree from Beijing University of Posts and Telecommunications (BUPT),Beijing, China,in 2003 and the Ph.D. degree from BUPT,Beijing,China, in 2010. Since 2010,she has been a lecturer with the Institute of Information Photonics and Optical Communications,BUPT. She is the author of more than 40 articles and holds 10 inventions. Her research interests include FEC and modulation technologies for backbone optical transmission and high-capacity, self-adaption and wired and wireless integrated technologies for optical access networks. Her awards and honors include the First Prize of Science and Technology Award 2018 (China Electronics Association), the First Prize of Science and Technology Progress Award 2014 (All-China Federation of Industry and Commerce),the First Prize of Innovation Achievement Award 2014 (China Association for Industry, Education and Research),the First Prize of Science and Technology Progress Award 2011 (Ministry of Education of the People’s Republic of China). Email: firstname.lastname@example.org;The corresponding author:Dongdong Wang,is an engineer in the 54th Research Institute of China Electronics Technology Group Corporation. He received the B.S. degrees in communication engineering from the Industrial and Commercial college of Hebei University, Baoding,China,in 2009 and M.S. degrees in control engineering from North China Electric Power University,Baoding,China,in 2012 and the Ph.D. degree in communication and information systems from Beijing University of Posts and Telecommunications (BUPT),Beijing,China,in 2018. From Apr. 2012 to May. 2013,he was a CDMA network administrator of China Telecom. His research interests focus on information theory and channel coding. The corresponding author,email: email@example.com. cn;Yongjing Ni,was born in 1981.She is a Ph.D.candidate at Yan- Shan university.She is now a lecturer of Hebei University of Science and Technology. Her research interests include computer ne