An Equlizer Implementation On FPGA Of PLC Communication System Based On OFDM

In order to use the power line to turns on the Internet, and enables the power line commucation to become the reality, power line communications system should select a modulation method of very strong anti-jamming. OFDM (Orthogonal Frequency Division Multiplex) is this kind of modulation method. Because of the characteristics of power line channel, it is need to use the equalizer in that system. This paper discusses the principle and implemention of equalizer in low-power line communication system based on in the OFDM.In OFDM system, the equalizer does not need to be so complex just like in the single-carrier wave system. It does not request to eliminate ISI and ICI completely yet. In this system, we use the Normalization LMS(NLMS) algorithm to implement equlizer. It uses in very large range for simple and little calculation quantum, although it has slowly convergence rate and not good to track the channel characteristic. The system need not channel estimation for NLMS algorithm. So system is simple and economical in resourse but lost in performance. The equalizer consists of time domain equalizer and frequency domain equalizer. The time domain equalizer is used to compensate channel before FFT. The frequency domain equalizer is added after FFT and used to adjust gain and phase of every chaild channel. The time domain equalizer is more compliex than the frequency domain equalizer. The time domain equalizer consists of 16 taps filter. The frequency domain equalizer is one tap filter. It is simply repetition, although every chaild channel need one tap. The system uses the FPGA realization. According to FPGA development flow, we complete verilog programming, function simulation, synthesis, simulation after synthesis, routing, simulation after routing and boarddebugging step by step. In fifth chapter, the paper has produced the procedure frame, simulation profile, synthesis result and performance analysis.The paper structure may divide into the introduction and the main body two bulks. Main body consist of the OFDM system introduction, the FPGA chip and development environment introduction, equalization algorithm in OFDM system and the result and performance analysis of FPGA realization. The paper key point is the latter two parts of contents.