Research On Channel Estimation Based On OFDM Of Low-voltage Power Line

Low-voltage power line channel has many inherent shortcomings, including themore noise, the large signal attenuation, the multipath effects and so on. Orthogonalfrequency division multiplexing (OFDM) technology is a special kind of multiple carriertransmission technology. It has become the main modulation technology of low-voltagepower line communication (PLC), because of it’s high spectrum efficiency, strongimmunity to frequency selective fading availably and excellent resistance against noise.Nevertheless, channel estimation is one of the key technologies for reliable transmissionin OFDM system. The accuracy of channel estimation directly affect the performance ofthe whole low-voltage power line communication system. This paper studied deeply onchannel estimation for OFDM system over low-voltage power line. Specific work wasfollows:Firstly, Based on cluster analysis channel estimation algorithm is proposed on thebasis of the traditional transform domain channel estimation algorithm. The time domainchannel impulse response within the length of cyclic prefix is classified to channelinformation and noise making use of the characteristics of OFDM system and the theoryof clustering. So the algorithm further reduces the noise influence on channel estimation,improving the accuracy of channel estimation. Performance of the algorithm is verifiedby simulation.Secondly, An improved algorithm is given based on line minimum mean squareerror (LMMSE) with low complexity channel estimation algorithm. The cluster analysismethod is applied to LMMSE with low complexity. So the estimation accuracy of timedomain channel response’s effective tap is increased, improving the estimation accuracyof Signal-to-noise ratio (SNR) and channel correlation matrix. In the end, theperformance of the channel estimation algorithm was enhanced. Performance of thisalgorithm is verified by simulation.Finally, On the basis of traditional decision feedback channel estimation algorithm,channel estimation algorithm based on the decision feedback with subcarrier weighting is proposed. The algorithm firstly analyzed the correlation between adjacent subcarriers infrequency domain. Then subcarrier weighting operation is carried out to reduce the effectof redundant information on channel estimation, improving the accuracy of the channelinitial estimation. So the performance of the whole decision feedback channel estimationalgorithm is enhanced. Performance of the proposed algorithm is verified by simulation.