Why We Can Not Surpass Capacity: The Matching Condition
Abstract
We show that iterative coding systems can not surpass capacity using only quantities which naturally appear in density evolution. Although the result in itself is trivial, the method which we apply shows that in order to achieve capacity the various components in an iterative coding system have to be perfectly matched. This generalizes the perfect matching condition which was previously known for the case of transmission over the binary erasure channel to the general class of binary-input memoryless output-symmetric channels. Potential applications of this perfect matching condition are the construction of capacity-achieving degree distributions and the determination of the number required iterations as a function of the multiplicative gap to capacity.
Keywords
Cite
@article{arxiv.cs/0510045,
title = {Why We Can Not Surpass Capacity: The Matching Condition},
author = {Cyril Measson and Andrea Montanari and Rudiger Urbanke},
journal= {arXiv preprint arXiv:cs/0510045},
year = {2007}
}
Comments
10 pages, 27 ps figures. Forty-third Allerton Conference on Communication, Control and Computing, invited paper