Design and development of non data aided estimation algorithm for carrier frequency-offset and I/Q imbalancing in OFDM-based systems

Orthogonal Frequency Division Multiplexing (OFDM) systems are particularly sensitive to carrier frequency offset (CFO) and Inphase and Quadrature (I/Q) imbalance. These parameters degrade the performance of OFDM-based system as they destroy the orthogonality between sub-carriers. In this paper, we designed an estimation algorithm which is based on non data aided technique for the CFO and I/Q imbalance by taking advantage of the inherent orthogonal structure in the OFDM signal. We particularly analyze the different standards of 802.11, the wireless local area network (WLAN) that are OFDM based to evaluate the performance of this algorithm. The simulation results show the improvement of new estimator over the existing one in the presence of I/Q Imbalance.

I. Introduction

Orthogonal frequency division multiplexing technology is widely used in wireless communications mainly due to its ability to cope with severe channel conditions, e.g., multipath and narrowband interference, without complex equalization filters. In OFDM the subcarriers are heavily overlapped which constitutes for its high spectral efficiency [1]. Also it uses the Fourier Fast Transform (FFT) and its inverse, the inverse FFT (IFFT) to create multiple orthogonal subcarriers using a single radio efficiently.