Exact free distance and trapping set growth rates for LDPC convolutional codes
David G. M. Mitchell, Alí Emre Pusane, Michael Lentmaier +1 more
Ensembles of (J,K)-regular low-density parity-check convolutional (LDPCC) codes are known to be asymptotically good, in the sense that the minimum free distance grows linearly with the constraint length. In this paper, we use a protograph-based analysis of terminated LDPCC codes to obtain an upper bound on the free distance growth rate of ensembles of periodically time-varying LDPCC codes. This bound is compared to a lower bound and evaluated numerically. It is found that, for a sufficiently large period, the bounds coincide. This approach is then extended to obtain bounds on the trapping set numbers, which define the size of the smallest, non-empty trapping sets, for these asymptotically good, periodically time-varying LDPCC code ensembles.
arXiv:1106.1414•IEEE International Symposium on Information Theory (ISIT)•Jul 1, 2011•16 citations