Improving HomePlug Power Line Communications with LDPC Coded OFDM

Power line communications (PLC) has received much attention due to the wide connectivity and availability of power lines. Effective PLC must overcome the harsh and noisy environments inherent in PLC channels. HomePlug 1.0 is the current PLC standard in North America. The physical layer of HomePlug 1.0 employs orthogonal frequency division multiplexing (OFDM) as well as concatenated Reed-Solomon and convolutional coding. Aiming to obtain higher PLC throughput, we investigate the performance of OFDM with low-density parity-check (LDPC) codes and compare the proposed scheme with HomePlug 1.0 ROBO mode. In our simulations, the PLC channel is modeled by multipath fading, with Middleton´s Class A noise (AWCN) model simulating the worst-case impulsive noise. We apply clipping to lessen the impact of impulsive noise. A simple but effective method is devised to estimate the variance of the clipped noise for LDPC decoding. In comparison with ROBO mode, the proposed scheme offers improved performance and lower computational complexity per decoded bit. Our scheme provides increased throughput by dispensing with ROBO mode´s repetitive transmission of information to gain time diversity