| Power Line Communication (PLC), refers to the communication technology which using the existed power line network as the transmission medium for transmitting data and exchanging information. As the power-line networks have the advantages of wide spreading, without re-wiring and easy connecting, so it has become a new hot topic reseach in communication field. As the power line is designed for power transmission, when it is used to communicate , its communications environment become quite poor, including hige noise and attenuation, and stong frequency-selective fading, so it is indispensable to choose applicable modulation technique for the realization of high-rate, effective data transmission in power line channel. Orthogonal frequency division multiplexing (OFDM) with its capability of efficient spectrum utilization, combating with the frequency-selective fading and noise strongly is considered as an ideal communication scheme of power line carrier communication. For OFDM systems, channel estimation is a key technology. The accuracy of channel estimation will have a direct impact on the performance of OFDM systems.This paper firstly introduces the development situation of low-voltage power line communication. Characteristics of the power line channel are analyzed, including noise, attenuation, impedance and the model of low-voltage power line channel is set up. Then the basic principles of OFDM, the method of realizing and the advantages and disadvantages of OFDM are discussed. Finally, channel estimation for OFDM has been studied. By analying the conventional adaptive LMS algorithm, an adaptive variable step-size algorithm based on fuzzy inference (AVSF) is proposed, which improve the step size by combining fuzzy inference. It is simulated in MATLAB environment.The comparision of the absolute error and mean square error show that the estimated values measured used AVSF is closer than the other two algorithms, which indicate the AVSF algorithm has good estimation performance.
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