The Study On Channel Estimation Technology In OFDM System

OFDM (orthogonal frequency division modulation) has gained more and more considerable attraction, and it is regarded as the key technology for the next mobile communication system, due to its high bandwidth efficiency and robustness against frequency selective fading channel. The radio channel is time-variant, frequency-selective and noisy, so the received OFDM signals are corrupted by inter-carrier interference. To demodulate the OFDM signals accurately, channel estimation algorithms are adopted. Many related algorithms are presented these years, among which pilot symbol assisted modulation is a practical channel estimation method in tracking the fast fading channel with low complexity and high accuracy.This paper examines the estimation algorithms based on block pilot arrangement: LS and LMMSE algorithms, as well as the algorithms based on comb-type pilot arrangement : linear, Gaussian and cubic-spine algorithms. The performances of the various algorithms are analyzed by MATLAB simulation.A new kind of pilot arrangement - diagonal line is proposed. And the author has suggested one kind algorithm in this foundation. This method fully uses the pilot message of the time axis, the sequence axis and the proximate Euclidian distance, which is not only saved frequency band but suitable to slow time varying channel. The feasible of the algorithm is confirms by MATLAB simulation. And the MATLAB simulation confirm that the algorithm is feasible for DVB system.