Channel Estimation Technique In OFDM System

With the increase of demand for the multimedia, and with the rapid development of internet, future broadband wireless communication system needs higher spectral efficiency and higher data rate. Currently in all the wireless schemes, multi-carriers modulation represented by OFDM is one of the most promising ways.In this thesis, the channel estimation technology is researched, including estimation algorithms based on pilot-symbol-aided and the blind estimation algorithms based on subspace. The channel frequency response (CFR) in pilot position is firstly estimated and then CFR in data position is estimated by interpolating processing in the channel estimation algorithms based on pilot-symbol-aided estimation. Different interpolation methods are proposed to implement the channel estimation. Then the pilot-symbol-aided channel estimation algorithm in OFDM system is analyzed. The simulation shows that BER is lower a level than that of without estimator in the system. Of these interpolation algorithms, the linear one is worse in performance but simple in calculation and easy to be realized, the cubic algorithm is better, but it is more complicated.More and more attention is paid to blind estimation methods by many researchers because of its highly spectrum-using. A improved subspace-based algorithm for blind channel estimation is proposed in this thesis by exploiting the redundancy introduced by the cyclic prefix, which aims at the algorithms complicated and imprecise. This method is more accurately under the same circumstance of Signal to Noise Ratio(SNR).