A New LDPC Coder/Decoder for PLC

Adding the ability of LDPC to an OFDM system gives rise to a robust and suitable technique for broadband PLC. However, despite LDPC codes performing admirably for large block sizes, real time operation and low computational effort require small and medium sized codes, which tend to be affected by channel SNR and errors in channel equalization. This paper deals with improvements made to an OFDM system for PLC, when using small/medium LDPC coding. Methods for fast encoding and decoding of LDPC codes are presented, highlighting the importance of assuring low encoding/decoding latency with maintaining high throughput. In the receiver, an improved intrinsic Log-Likelihood Ratio (LLR) estimator to the LDPC decoder – the ILE-Decoder is presented, which better estimates each subchannel noise parameters. The assumptions and rules that govern the estimation process via subcarrier corrected-bit accounting are presented, and the Bayesian inference estimation process is detailed. Simulation results in a PLC environment that confirm the good performance of the proposed LDPC coder/decoder are presented. At the end conclusions and final comments are addressed. KeywordsLDPC; OFDM; PLC;