Research On OFDM-Based Cognitive Radio Of Channel Estimation In The Power Line Carrier Communication

Power Line Communication (PLC) technology, is a means of communication using power lines to transmit variety data signals. Power line communication of wide transmission line needs no additional lines investment, and the basic line is solid and reliable. Therefore power line communication has very wide application prospect and practical value. However, the use of power line carrier communication, must be overcome the attenuation and serious noise for as non-professional transmission lines.The rise and development of cognitive radio technology provides a new way to solve the problem of communication attenuation. Cognitive radio technology can be very easily searched the entire available spectrum where the noise smaller sub-channels are, by calculating the interference temperature of each sub-channels ,and given appropriate threshold can be divided into available domains, the unavailable domain and the middle domain, therefore we can select the better conditions sub-channels for reliable communication. Cognitive radio technology through the real-time detection outside channel environment, adjust accordingly certain operating parameters to provide the best communication results.This paper introduces the low voltage power channel time-varying attenuation, multipath and other features, and specifically analyzes the impact of channel transmission characteristics in the low-voltage power line carrier communication. This paper studies the low-voltage power line channel attenuation and low-voltage power line channel modeling methods and deduces in detail related modeling method. There presents a top-down model, the regression model, simplified time-varying channel model, such as several low-voltage power line communication channel model, and simulates all model to find their respective advantages and shortcomings.After established the low-voltage power line channel model, the paper introduces the NC-OFDM system theory and model, and focus on the low voltage power communication system channel estimation algorithm. In the design of the pilot pattern, we analyze several proposed pilot method for NC-OFDM available sub-carrier discontinuous characteristics, then we compare and analyze several channel estimator with the complexity and the estimated performance. Finally, we give the low-voltage power line NC-OFDM channel estimation of simulation performance. Simulation results show that compared to traditional LS estimation, the proposed method can get the channel gain of about 3dB.