A Improved Subspace Method For Blind Channel Estimation In OFDM Systems

OFDM is a kind of high-speed wireless transmission technology, which bases on the principle that the high-speed serial data will be broken down into multiple low-speed parallel data, and the parallel data be modulated by exploiting the different carrier modulation. So through the joint coding to all subcarriers,OFDM system can get a good capacity of the anti-multipath fading and the delay diffusion, and maintain a higher transfer rate.This paper have studied the channel estimation parameters of the OFDM systems.Firstly the article discussed the development status quo of channel estimation technology in OFDM systems,and then on the basis of the literature [32-34],a improved OFDM blind channel estimation model is proposed. This method has the advantage that the algorithm still works for OFDM systems when the cyclic prefix is greater than or less than the number of channel bands. The simulation results also show that in the situation that the cyclic prefix is greater than the number of channel bands,the improved algorithm convergence faster than the algorithm mentioned in the literature [32-34].Finally, this article also introducd the virtual subcarrier technology on the base of the improved OFDM channel estimation algorithm. On the hand this connection make the application of the algorithm better in the absence of cyclic prefix, on the other hand it could potentially improve the bandwidth utilization. The algorithm that uses subspace decomposition method does not want the the second-order statistics of the receiving signals, But exploites the receiver signal decomposition directly. Simulation results show that the algorithm is very practical, and in all kinds of circumstances for CP, the performance is excellent.