FRFT Based Timing Estimation Method for an OFDM System

The Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation (MCM) technique which is adopted by many wireless communication standards for transmitting data at very high rates over time dispersive radio channels. In an OFDM system, the timing estimation is extremely important for maintaining orthogonality among the subcarriers. In this paper, a method of timing estimation is proposed for an OFDM system. The proposed method used chirp signal as a training sequence and employed the fractional Fourier transform (FRFT) as a tool to localize the training sequence (chirp) at the receiver. The comparative study showed the superiority of the proposed estimator in terms of mean and MSE of timing offset. The MSE of timing offset with proposed method was found to be 76% (5 dB SNR) and 63% (8 dB SNR) lower than Awoseyila et al.’s method in HIPERLAN/2 indoor channel-A and in Wi-Max system (strong fading channel), respectively. However, the improvement in MSE is obtained in the proposed method at the cost of increased computational complexity, in terms of N/4-1+N log2 N more complex multiplication than the Awoseyila et al.’s method.