Title :
Informed Dynamic Scheduling for Belief-Propagation Decoding of LDPC Codes
Author :
Vila Casado, A.I. ; Griot, M. ; Wesel, Richard D.
Author_Institution :
Univ. of California, Los Angeles
Abstract :
Low-density parity-check (LDPC) codes are usually decoded by running an iterative belief-propagation, or message-passing, algorithm over the factor graph of the code. The traditional message-passing schedule consists of updating all the variable nodes in the graph, using the same pre-update information, followed by updating all the check nodes of the graph, again, using the same pre-update information. Recently several studies show that sequential scheduling, in which messages are generated using the latest available information, significantly improves the convergence speed in terms of number of iterations. Sequential scheduling raises the problem of finding the best sequence of message updates. This paper presents practical scheduling strategies that use the value of the messages in the graph to find the next message to be updated. Simulation results show that these informed update sequences require significantly fewer iterations than standard sequential schedules. Furthermore, the paper shows that informed scheduling solves some standard trapping set errors. Therefore, it also outperforms traditional scheduling for a large numbers of iterations. Complexity and implementability issues are also addressed.
Keywords :
decoding; graph theory; message passing; parity check codes; scheduling; LDPC codes; belief-propagation decoding; dynamic scheduling; factor graph; iterative belief-propagation; low-density parity-check; message-passing schedule; Belief propagation; Convergence; Dynamic scheduling; Intrusion detection; Iterative algorithms; Iterative decoding; Maximum likelihood decoding; Message passing; Parity check codes; Scheduling algorithm;
Conference_Titel :
Communications, 2007. ICC '07. IEEE International Conference on
Conference_Location :
Glasgow
Print_ISBN :
1-4244-0353-7
DOI :
10.1109/ICC.2007.158