A Comparative Study of In-phase and Quadrature (IQ) Imbalance Estimation and Compensation Algorithms for OFDM Receivers

Systems based on orthogonal frequency division multiplexing (OFDM) are subject to limitations caused by the radio front end. These deficiencies are the result of imbalances between the In-phase (I) and Quadrature phase (Q) branches. For zero-IF receiver design which is commonly used in practice, IQ imbalance has been identified as one of the most critical issues. The signal to noise ratio (SNR) at the receiver, data rates and the supported constellation are some key metrices severely impacted by this imbalance. In this paper, the impact of IQ imbalance on OFDM receivers and digital techniques for mitigating the effect of IQ imbalance are explored and studied. We analyse IQ imbalance models and estimation techniques based on a low-complexity feed-forward and a standard-independent IQ imbalance compensation algorithms. The outcome of the constellation method may suggest that the proposed techniques increase performance appropriately.