IQ imbalance estimation and compensation schemes based on time frequency interferometry for OFDM

A direct-conversion receiver (DCR) reduces the power consumption and cost. However, DCR in Orthogonal frequency division multiplex (OFDM) systems suffer from IQ imbalance. Until this time, many algorithms are proposed to compensate IQ imbalance in OFDM. However, the complexity is still considerable work. On the other hand, time-frequency interferometry-OFDM (TFI-OFDM) system has been proposed to achieve an accurate channel identification property with small number of pilot symbols. In this paper, we propose a novel IQ imbalance estimation and compensation scheme using TFI-OFDM system. In the proposed system, by using the feature of the TFI pilot symbols, we can identify IQ imbalance without high calculation complexity. Furthermore, by using subcarrier selection, the influence of the noise power can be reduced. From the simulation results, the proposed scheme can achieve the low-complexity IQ imbalance estimation and compensation without a degradation of the BER performance.