Novel Coarse Timing Synchronization Methods in OFDM Systems Using Fourth-Order Statistics

In this paper, the problem of coarse timing synchronization in orthogonal frequency-division multiplexing (OFDM) systems is investigated, and two new timing metrics with better performance are presented. The new metrics take advantage of two novel differential normalization functions that are based on the fourth-order statistics and are designed depending on the value of carrier frequency offset (CFO). The proposed timing metrics are theoretically evaluated using two different class separability criteria. It is shown that the new schemes considerably increase the difference between the correct and wrong timing points in comparison with previous methods. The computational complexity of the new methods is obtained, and their superior detection performances are also demonstrated in terms of probabilities of false alarm and missed detection. The results indicate that due to a significant improvement in missed detection probability (MDP), the new methods offer a considerably wider range of acceptable thresholds.