FPGA Design And Implementation Of Channel Estimate Based On OFDM System

OFDM(orthogonal frequency division modulation) is regarded as the key technology for the next mobile communication system.Due to its high bandwidth efficiency and robustness against frequency selective fading channel.But the radio channel is time-variant,frequency-selective and noisy;the received OFDM signals are corrupted by intercarrier interference.Channel estimation algorithms are adopted to demodulate the OFDM signals accurately.Nowadays,the theoretics and simulation performance of channel estimation for OFDM have matured.But it is considered to be a key point to the implement of channel estimation system based on hardware.This paper analyses the performances of some channel estimation methods,then puts emphasis on building up a channel estimation platform for OFDM baseband system which bases on Field Programmable Gate Array (FPGA).This paper analyses the performances of block pilot arrangement and comb-type pilot arrangement.1) Use matlab to simulate the the slow-fading estimation algorithms based on block pilot arrangement(LS,LMMSE and SVD algorithms),then analyses their performances.2) Use matlab to simulate the fast-fading channel estimation algorithms based on comb-type pilot arrangement(constant,liner,gauss),then analyses their performances.This paper puts LS algorithm based on block pilot arrangement as the channel estimation method in the implement of hardware.Because LS algorithm is easy,and performs good after it is optimized by liner.In FPGA designing part,this paper designs the transmitter and receiver apart.The transmitter includes constellation mapping,pilot insert,IFFT translation,multiply, cyclic prefix insert modules,and the receiver includes cyclic prefix expurgate,divide, FFT translation,data separate,channel estimate,constellation demapping modules.The whole system is built up and passed through the software simulation.The final results show effectiveness of the design.The software platform of QuartusⅡ8.1 and VHSIC Hardware Description Language(VHDL) are used to design.