Analysis Of Impulse Noise In The PLC-OFDM System

PLC (Power Line Communication), because of its large coverage area, network equipment, low cost, convenient degree is high, which was used to transmit voice, data and so on, has the broad application prospect and market demand. However, complex channel environment, such as noise, interference, fading and multipath effect impact PLC, seriously.OFDM (Orthogonal frequency division multiplexing) is a multi-carrier modulation technology, with good anti-noise performance, anti-multipath interference and high spectral efficiency. It has been widely used in wireless communication, is one of the key techniques of the transformation of3G to4G in the process, which has been widely used in wireless communication, and it is also the key technique to realize space-time coding, diversity and suppress the inter symbol interference between codes.OFDM is applied to the low-voltage PLC in order to adapt to the complex channel environment. Currently, the channel estimation is a hot research direction of application of OFDM in communication technology in PLC. In the thesis, algorithms of channel estimation for OFDM based PLC system is studied, which has the ability to track channel characteristics, remove the multipath effect and improve the performance of PLC.Firstly, this thesis introduces OFDM technology and its application in PLC transmission system, and gives a brief analysis of the characteristics of low-voltage PLC transmission channel. Aiming at multipath fading and noise interference in PLC channel, three kinds of pilot based channel estimation algorithms are studied, including LS, LMMSE and SVD. In addition, a channel estimation algorithm based on DFT threshold decision is studied. Secondly, this paper analyzes the performance of receiver in OFDM system under pulse-noise environment, and expounds the necessity of compensation for additive pulse-noise. Based on the pulse-noise model, a method of noise reduction on the receiving end by minus equivalent signal of pulse noise signal is studied. In addition, an accurate pulse-noise channel estimation for power line is studied, which inserts pilot symbols in two consecutive OFDM symbols for channel estimation. Finally, the research work is summarized and prospected.