Analysis and Exploitation of the Noise Correlation in MIMO Power Line Communications in the FM Band

This letter analyzes noise correlation in multiple-input multiple-output (MIMO) power line communications (PLC) in the 2-108 MHz band. The focus is on the 88-108 MHz range, which in most countries is assigned to frequency modulation (FM) broadcasting. The study reveals that noise correlation is very high in frequencies impaired by FM ingress and very low in frequencies where background noise dominates, yielding a bimodal behavior. The influence of noise correlation in orthogonal frequency division multiplexing systems is also addressed. It is shown that the spectral leakage of the rectangular window spills the correlation introduced by FM signals to the adjacent frequencies. Hence, the lower the number of carriers, the larger the performance gain obtained by adding a whitening transformation to linear precoded systems. Based on these findings, the feasibility of MIMO PLC in the FM band is assessed. Results indicate that 50% of the channels attain bit-rates larger than 9 Mbit/s with an injected power spectral density as low as -100 dBm/Hz.