Short-block LDPC codes for a low-frequency power-line communications system

The TWACS power-line communication system is used by electric utilities for communicating over long distances with power meters and other devices. Data packets tend to be short, and increasing demand for bandwidth requires that error detection and correction add minimal overhead. We have investigated low-density parity-check (LDPC) codes as a replacement for the existing error control coding scheme. In this paper we investigate the error detection capabilities of LDPC codes with high rate and short block size. Under these constraints, increasing the density of the code adds short cycles to the Tanner graph of the code. This degrades the overall error rate, but we have found that it also improves the undetected error rate, resulting in a trade-off between error correction and detection that can be adjusted by changing the density of the code. Using this approach, an LDPC code can be designed that improves on both the error detection and correction capabilities of the existing scheme.