Carrier frequency offset compensation method for digital power line carrier systems

The transmission performance of a digital power line carrier system with adaptive equalizer degrades in the presence of the carrier frequency offset (CFO). Therefore, accurate CFO estimation and compensation is necessary. In this paper, we propose a CFO estimation method suitable for a digital power line carrier system with adaptive equalizer in the presence of delayed propagation paths. The proposed CFO estimation method estimates the CFO from the measured phase rotation per symbol which is obtained by the measurement of autocorrelation of a 4PSK training sequence. By setting the time separation for autocorrelation measurement to the training sequence length, the accurate CFO estimation is achieved in the presence of delayed propagation paths. In order to achieve sufficiently accurate CFO estimation in a low SNR condition, averaging the instantaneous autocorrelation measurements is done by a simple first-order filter. It was confirmed by computer simulation that even in the presence of delayed propagation paths, by using the proposed CFO estimation method, a digital power line carrier system with adaptive equalizer achieves a BER performance close to the case of no CFO.