Research On Channel Estimation Based On OFDM Communication System Of Low-Voltage Power Line

Low-voltage power line communication utilize the lines of the transmission power as a transmission medium for data transmission and information exchange, and it has a lot of advantages, for example, without re-wiring, convenience of connection, low cost and so on, therefore having been paid much attention in the field of smart grid, internet of things, broadband access and other areas. However, there are characteristics of noise interference, multipath attenuation, time variation and so on in the low-voltage power line channel, which seriously affect the communication quality of the system. Orthogonal frequency division multiplexing(OFDM) technology by virtue of its ability to effectively combat multi-path fading and strong ability of anti noise and higher spectrum utilization and other advantages become the preferred technology of modulation for the low-voltage power line communication, and the channel estimation as a key technology in OFDM system, the accuracy influences the performance of the entire power line communication system directly. There is in-depth study on the channel estimation technique for low-voltage power line based on OFDM communication system in this paper, and the specific contents are as follows:Firstly, an improved channel estimation algorithm is given on the basis of the least square(LS) criterion of channel estimation algorithm. The algorithm by mean of averaging in the frequency domain and multiple random order and then takes the average value in the time domain to reduce noise interference of the power line channel, improve the channel estimation performance effectively, and overcomes the defect of the LS channel estimation algorithm without noise suppression.Secondly, in view of the channel estimation algorithm based on threshold decision is made to improve. The channel estimation algorithm based on discriminant analysis is given, and the algorithm utilize the characteristics of non-sample-spaced channel and the discriminant analysis method to establish the dynamic decision threshold, accurately discriminating the effective channel information of channel response estimates and noise information to further suppress the effect of noise on the channel estimation and improve the accuracy of the channel estimation.Finally, aiming at linear minimum mean square error(LMMSE) channel estimation algorithm need to know in advance the channel statistical characteristics, signal-to-noise ratio and inversion of high dimensional matrix with a high computational complexity, we give a simplified algorithm, the algorithm by using energy of the time domain channel response and average signal to noise ratio for channel estimation to reduce the computing complexity of LMMSE channel estimation algorithm effectively.The performance of these three channel estimation algorithms are verified by simulation.