Research Of Channel Estiamtion Algorithm Based On OFDM System

Theory analysis and computer simulation of wireless channel parameter estimation has been completed based on wireless OFDM(Orthogonal Frequency Division Multiplexing) communication system which has been divided into two aspects: One is channel estimation algorithm with pilot based on Least Square Estimator, the other is semi-blind and blind channel estimation algorithm based on Sub-space Decomposition.Firstly, channel estimation algorithms about LS were overviewed which are studied by many documents. Aimed at their defects on the serious frequency selected fading channel, an improved method is proposed in this paper which employed two order polynomial interpolation to estimate the channel frequency responses without the pilots, and compare the estimation error between the improved algorithm and the one studied by one of documents. At the same time, estimation steps and compute formulas were introduced.Secondly, due to the blind and semi-blind algorithm based on Sub-space Decomposition needing large amount of compute, an frequency-domain Sub-space Decomposition was proposed here. Because of the processing made all in the frequency-domain, the amount of compute decreased sharply. An semi-blind algorithm based on Frequency-Domain Sub-space Decomposition is presented ,and show the construction of estimation matrix and the compute result.Lastly, combining the different characteristic between the serious frequency selected fading channel and indoor wirless channel, performances of the two proposed methods are demonstrated by computer simulation with MATLAB. The mean square error and bit error ratio for estimation results are also discussed in this paper.