Study On Low Voltage Powerline Carrier Communication Technique Based On Adaptive OFDM

With the inceasing demanding of high-rate broadband service such as data,video,image and so on,powerline behaving as an ubiquitous, no new wire, high channel capacity broadband communication medium brings up people's attention.However,powerline provides us a horrible communication environment. It means that it's indispensable to choose applicable modulation technique and design error detection and correction project for the realization of high-rate ,effective data transmission in powerline channel.Therefore in the paper,a high-rate adaptive OFDM system is studied with a simulation method based on a specific powerline channel.It is summarized as follows:1.Characteristics of lower-voltage powerline channel are analyzed in detail,including noise,attenuation,impedance and time varying,providing reference for the designing of communication system.2.A OFDM system is established based on the specific channel and two adaptive OFDM algorithms, rate maximization and power minimization,are proposed,one of which seeks to maximize transmission rate,another seeking to minimize transmission,both being applicable for powerline communication system to meet different needs..3.Two adaptive algorithms are simulated with Matlab programme based on the established OFDM system. The simulation result shows that for rate maximization, merely increasing transmission power cann't improve transmission rate obviously when the rate is relative large and the BER performance of rate maximization is superior to fix-bit modulation even under the circumstances of lower mean SNR.It also indicates that BER performance of power minimization is apparent better than one of fix-bit modulation when the total number of bits per OFDM symbol is less than 512, whereas it gradually becomes worse when the number gradually exceeds 512.