Constructing LDPC codes with given distribution pairs by quasi Tanner graphs

【摘要】：正In this paper,we advance a method for constructing low-parity density-check(LDPC)codes having a large girth greater than 6 by directly connecting variable nodes of the Tanner graphs,called quasi-Tanner graph(QTG)constructing algorithm.Re- striction on distribution pairs for the method is provided in terms of code length,row and column weight.The upper bound on the girth of a Q-T graph is derived using initialization parameters of the graphs based on a connection strategy provided to approach the bound.Finally,simulation results show that LDPC codes constructed by QTG algorithm perform better than random codes with the same distribution pairs.