A Robust Estimation of Residual Carrier Frequency Offset With I/Q Imbalance in OFDM Systems

In this paper, we focus on improving the accuracy of frequency offset estimation for an orthogonal frequency-division multiplexing (OFDM) system under the conditions of the joint impairments in both carrier frequency offset (CFO) and in-phase/quadrature (I/Q) imbalance. To propose a robust CFO estimation scheme and to benchmark its performance, the performance of the conventional frequency estimation algorithm in the presence of I/Q imbalance is analyzed, and some modifications to the conventional estimation scheme are highlighted. We show via simulations that such a design achieves a remarkable robustness against I/Q imbalance; thereby, the proposed scheme can efficiently estimate the CFO, irrespective of the I/Q mismatch.