An Investigation On Channel Estimation Algorithms For 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 intercarrier interference. To demodulate the OFDM signals accurately, channel estimation algorithms are adopted. This paper examines the slow-fading estimation algorithms based on block pilot arrangement: LS and LMMSE algorithms, as well as the fast-fading channel estimation algorithms based on comb-type pilot arrangement: linear and transform domain interpolation algorithms. The performance of the various algorithms are analyzed by matlab simulation. The paper gives three advised algorithms: 1) The linear interpolation and transform domain interpolation algorithms are replaced by the spline cubic and MMSE algorithms to reduce the complexity of achieving the transfer function; 2) LMMSE algorithm is presented to estimate the transfer function of the pilot signals;3) To balance the bit error rate of the data signals in the center and brim, the paper uses the asymmetric pilot arrangement. The values of the distance of the center and the brim are found by Newton interpolation. The simulation results demonstrate the three advised algorithms are preferable choices for the OFDM system.