Timing Offset Correction and Channel Tap Estimation of OFDM Systems Over Frequency Selective Fading Channels

Abstract

In OFDM systems we need to perfectly time synchronize the receiver to the transmitter to maximize its BER performance. In the absence of timing synchronization the channel estimation can never be optimum. Both timing synchronization and optimum channel estimation are the essential requirements to maximize the performance. We present an algorithm that uses the cyclic prefix to determine the timing offset of the system. The same algorithm can be used to determine the number of channel taps and their variances also. Determination of number of channel taps helps us in minimizing the length of the cyclic prefix to be added and also in the channel estimation, to minimize the variance of the estimation error. The knowledge of the variances of the channel taps helps us in further reducing the estimation error. We present in this paper the timing offset corrected MMSE channel estimation and show by simulations the effectiveness of the method presented.