The Research Of Channel Estimation Technology For Power Line Communication System Based On OFDM

The low-voltage power line networks cover a wide range of areas and easy toconnect. Therefore, application of it in broadband access and intelligent home networkdraws more and more attention. OFDM (Orthogonal Frequency Division Multiplexing)technique can effectively overcome multipath interference and noise on the power linechannel, easy to implement high-speed transmission and has high spectral efficiency.Therefore, OFDM technique has been the digital modulation technique for manycommunication standard, and also had a good application prospect in power line carriercommunication.The paper researches the channel estimation technology for power line communication system based on OFDM.Firstly, the power line communication standards based on OFDM are introduced,and focuses on the G3-PLC standard and PRIME standard. The paper detailed describestheir system block diagram and detailed parameters, and simulate their transmit signalpower spectral density by Matlab.Secondly, the design of PLC system based on OFDM is analyzed, and introducesthe basic principles and key technologies of OFDM, and focus on the system blockdiagram and detailed parameters of PLC system based on OFDM.Thirdly， the channel estimation technology for power line communication systemis introduced: First，introduce the channel characteristics of the power line channel,including input impedance characteristics, noise characteristics, as well as fadingcharacteristics. Second, explain the points of the non blind estimation algorithm inOFDM, including:(1)selection and insertion of the pilot in transmitter; comb pilots andblock pilots are discussed in this chapter.(2)the algorithm of getting channel informationfor pilot; principle and characteristics of channel estimation a1gorithm based on Ls，MMSE, SVD are introduced. Simulation result indicates that MMSE has the betterperformance, but it is too complicated to be realized in real life; SVD is easier thanMMSE, but with the signal-to-noise ratio increased, its performance becomes worse; theLS’s performance has been proved lower2-4dB than MMSE, however, it is easy toinplement.(3)get all channel information through pilot’s channel information. As theinserted pilot algorithms linear interpolation, Gaussian interpolation, Cubicinterpolation are described and compare. Last, a improved LS algorithm is adopted in this paper, and proves that theimproved algorithm performance greatly better than LS algorithm even under badchannel environment.The results of this paper have some value for the practical application of PLCsystem, and also laid the foundation for OFDM-based powerline communication chipcompletely independent intellectual property rights for the future design.