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

Abstract

AbstractA direct‐conversion receiver (DCR) can reduce the power consumption and cost. However, a DCR with orthogonal frequency‐division multiplex (OFDM) suffers from IQ imbalance. Until this time, many algorithms have been proposed to compensate IQ imbalance in OFDM systems. However, the calculation complexity is still a considerable work to achieve the implementation of a DCR. Moreover, an accurate channel identification is also necessary for a DCR. Recently, time‐frequency interferometry‐OFDM (TFI‐OFDM) system has been proposed to achieve an accurate channel identification property with small number of pilot symbols, and it has a periodicity of pilot amplitude. In this paper, we focus on the feature of TFI and propose a novel IQ imbalance estimation and compensation schemes using TFI‐OFDM system. In the proposed system, by using the feature of the TFI pilot symbols, we can identify an 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 for IQ imbalance estimation and compensation without a degradation of the bit error rate performance. Copyright © 2014 John Wiley & Sons, Ltd.