A Joint Blind Timing and Frequency Offset Estimator for Asynchronous Multicarrier CDMA Systems

Abstract

In this paper, a joint blind timing and carrier frequency offset (CFO) estimator for multiuser asynchronous multi-carrier code division multiple access (MC-CDMA) systems over frequency selective fading channel is proposed. Through properly choosing the over sampling factor and the number of received samples, the estimation can be resolved using the subspace approach. The use of decoupled subspace approach decouples the multiuser parameter estimation to multiple single user problems, thus improves the algorithm computational efficient. Using the small perturbation analysis, the approximate mean square error (MSE) in estimating CFO can be computed. The Cramer-Rao bound (CRB) is also derived to obtain the lower bound of the CFO estimation error. The accuracy of timing estimation is measured in terms of the probability of acquisition. Our simulation results show the robustness and effectiveness of the proposed joint timing and CFO estimator, in terms of its strong resistance to noises, near-far problem and multipath fading