Two-Stage Frequency Synchronization for Uplink MC-CDMA System

In this paper we propose a two-stage carrier frequency offset (CFO) estimator for frequency synchronization in the uplink of MC-CDMA system. The proposed approach is non-data-aided and uses only the second order statistics (SOS) of the received signal. In the first stage, determinant of a matrix which is a function of the CFO is used as a cost function. A linear search is performed and the search point which minimizes the determinant value is taken as the estimated CFO. This is called coarse synchronization. In the second stage, adaptive LMS algorithm is used to estimate the CFO. The LMS algorithm is initialized with the estimated CFO from the first stage. The application of the gradient type algorithm is due to the local convexity of the cost function. The performance of the proposed estimator is evaluated through computer simulations.