A new method of detecting cycles in Tanner graph of LDPC codes

摘要

To improve the performance of LDPC codes, we should detect and eliminate cycles in Tanner graph of the parity-check matrix when we make LDPC codes. We improved a logic algebraic algorithm in computing entire routes between the nodes of a communication network, and found a new method of detecting cycles in Tanner graph of LDPC codes. This method applied the logic algebraic calculation rules. First transformed the parity-check matrix and then constructed the relative matrix of the Tanner graph. Through integrating and deleting rows of relative matrix and correcting some elements, this new algorithm can detect all the cycles in a Tanner graph of LDPC codes which code length is n and information bits number is k, just needing integrating and deleting n-1 times and correcting k times. The calculation steps of the algorithm is shown detailed by an (8, 4, 2) LDPC example and its correctness have been validated.