Research On Low Voltage Power Line Communication Mode Of Single-carrier4QAM Based On The TH Precoding

Low voltage power line communication is a means of communication whichuses the low voltage power line as the communication medium to transmit the data.This technology has the characteristics of accessing conveniently, no wiring,constructing speedily and wide distribution compared with other cablecommunication medium. The application prospect on smart home and broadbandaccess of Internet has been concerned widely, and it is also one of the mostlytechnology, which can resolve the problem (we call it the last kilometer). However,the low voltage power line channel has the characteristics of stronger time-varyingand bigger interference compared with other cable communication medium, so wemust choose proper transmission modes which has stronger resistance tointerference to transmit data. Now the OFDM scheme has been used in the actualpower line modem chip, this technology has the characteristics of high bandwidthefficiency and strong anti-interference ability, but the transmitter and receiver needthe transform of IFFT/FFT, so the equipment is relatively complex. The paperproposed a modulation method of single-carrier4QAM based on TH pre-coding,which adopts the mode of combining TH pre-coding and adaptive equalizer. Thesignals are pre-equalized by the TH pre-coding filter in the send end in the basis ofchannel estimation, and the signals are equalized again by the adaptive equalizer inthe receiver. So this method can suppress the ISI which is produced by themulti-path effect. It can reach similar performance when the complexity is reducedcompared with OFDM technology.The paper firstly introduced the characteristics of channel and noise in the lowvoltage power line, and shows the simulation of the low voltage power line channeland noise model, and then describes the basic principles, realization, advantages anddisadvantages of OFDM technology which is commonly used in the power linecommunication, two key technologies in the OFDM which are channel coding andchannel estimation based on the pilot were discussed in detail. Finally THpre-coding and adaptive equalizing technologies were studied. Two adaptivealgorithms and the application of adaptive filter on system identification and theprinciple of single-carrier QAM were introduced in detail, at the same time, thesimulation results were given. At last, we choose proper parameters based on theabove. The comparison on error performances between OFDM technology andsingle-carrier4QAM based on TH pre-coding was done, we can get the conclusionthat their error performances are similar at the same condition but the complexity ofsingle-carrier4QAM based on TH pre-coding is less than OFDM technology from the simulation results.