The Research Of Channel Estimation Technology In OFDM-CDMA System

CDMA is the key technique of 3G.At the same time,OFDM has many advantage such as robust against narrowband inferference and multipath,highfrequency efficiency. Multicarrier-CDMA(MC-CDMA) systems combine many advantage both of OFDM and CDMA ,which make it is likely to be a potential contender for the next generation mobile communication systems.Channel estimation is a key technology in communication domain, which is the basis of coherent detection, demodulation and equilibrium.In this paper ,the interpolation methods of channel estimation based on two-dimentional discrete pilot arrangement in MC-CDMA systems are discussed.The paper set up simulation platforms using MATLAB and realize these channel estimation methods discussed.Firstly,the 2-D wiener filter and the cascaded 1-D Wiener filter were researched and realized. Secondly, the performance simulation and analysis of these methods such as linear interpolation polynomial interpolation,Spline-cubic interpolation and an improved dicision-directed are performed. In addition to ,a low pass filter using FFT and IFFT is also used to reduce the noisy components of a channel estimation obtained by an interprolation filter. At last ,a improved channel estimantion method based on transform domain filter is presented for MC-CDMA and realized.