Performance evaluation of decision-directed carrier synchronization for SC-FDE schemes

In this paper we consider a decision-directed Carrier Frequency Offset (CFO) estimation technique employed in joint equalization and synchronization schemes for broadband wireless systems using single carrier (SC) modulations combined with frequency domain equalization (FDE). We build a model for the estimates, explain the reason for their biased behavior and validate the theoretical results through simulations. The model applies to ideal Additive White Gaussian Noise (AWGN) channels. The use of the AWGN channel is justified because, although SC-FDE is usually applied to frequency selective fading channels, the signal at the output of the FDE presents no time dispersion effects. The performance analysis conducted on the CFO estimator suggests that the model describes conveniently the behavior of the system for the Signal-to-Noise Ratio (SNR) operating range.