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

Low-voltage power line will be restricted by its inherent shortcomings when used as communication medium, such as strong signal attenuation, different kinds of noises, multipath, etc., which needs further study. Orthogonal frequency division multiplexing(OFDM) technology is considered to be a kind of modulation technology which can effectively weaken various kinds of adverse factors on the low-voltage power line channel. Channel estimation is one of the key technologies of OFDM, and its result accuracy directly affect performance of low voltage power line communication system. This paper studied channel estimation technology widely. The specific content is as follows:Firstly, this paper presents channel estimation algorithm based on discriminant analysis on the basis of traditional DFT channel estimation algorithm. The algorithm distinguishes more accurately on time domain channel information in the cyclic prefix and noise through the idea of discriminant analysis to determine threshold value, which further improves the channel estimation accuracy.Secondly, we only deal with the high frequency part of the general transformation channel estimation algorithm through a low-pass filter, and improve the fault that noises are not processed in the low frequency part. We first select effective tap in time domain through SNR estimation, and then transform the processing result into transform domain, and deal with noise further by using low pass filter, which further improves the channel estimation accuracy.Finally, we propose a channel estimation method which takes mismatch sequences as the suffix under the low-voltage powerline channel. In view of the PN sequences for channel estimation, this paper proposes a channel estimation method which takes mismatch sequences as the suffix for those shortcomings such as energy leakage phenomenon and domain unflatness amplifiers noises in frequency due to the cyclic autocorrelation function sidelobe is nonzero, which influence the accuracy of channel estimation and so on. This method does not need additional added pilot and guarantees the spectrum efficiency. Meanwhile, because sidelobe of the mismatch sequences is zero, we can reduce the energy leakage and obtain more accurate channel estimation results when using it to do the channel estimation.Under the low-voltage power line channel, performance of the three algorithm above have passed simulation.