Study Of Channel Estimation For OFDM Communication Systems

Data transmission in wireless channels with high speed and reliability is required in future wireless systems. Orthogonal Frequency Division Multiplexing(OFDM) is one of the best solutions to this problem. It can strongly combat multipath and dispersive channel interference. Using DFT, it can be easily realized in transceivers. Therefore, the application of OFDM in wireless communication systems is robust and remarkable.This thesis mainly focuses on the algorithms for channel estimation in the OFDM systems including pilot assisted channel estimation and channel blind estimation. Above all, the basic principle and key technologies of OFDM are analyzed. Then influence on performance of systems resulted from parameter non-synchronization and error from channel estimation are investigated respectively.In the section for channel estimation algorithms based on pilot assisted, the existing algorithms including Wiener filtering in the sense of MMSE and interpolation filtering in the sense of LS are summarized systemically, emphasis is on the discussion of two-dimensional and separated two one-dimensional Wiener interpolation filtering. And the performance of different algorithms are analyzed and discussed.In the another section for channel blind estimation, an improved algorithm is proposed based on the subspace blind estimation algorithm. The improved algorithm improves its performance in theory when channel noise is non-AWGN noise. In the end, a algorithms grounded on conventional channel blind estimation are introduced briefly.