Blind frequency offset estimator for OFDM systems-efficient minima search

This paper discusses effective schemes for searching the global minimum of the cost function used in a blind frequency-offset estimator for OFDM systems. The estimator has been discussed and requires searching for the global minimum in a cost function containing multiple maxima and minima. Little has been discussed on how to conduct the search efficiently when the offset range is large. The schemes suggested are more efficient than a uniform exhaustive search and does not require the setting of a descent step-size that critically affects the performance of gradient descent techniques. In the coarse search for minima, a property of the cost function and a criterion are used to reduce the number of DFTs and intervals where the local minima need to be searched respectively. And by transforming the problem to one of root search, the number of iterations to reach convergence is reduced significantly.