Analysis and Compensation of Transmitter IQ Imbalances in OFDMA and SC-FDMA Systems

One limiting issue in implementing high-speed wireless systems is the impairment associated with analog processing due to component imperfections. In uplink transmission of multiuser systems, a major source of such impairment is in-phase/quadrature-phase imbalance (IQI) introduced at multiple transmitters. In this paper, we deal with orthogonal-frequency-division multiple access (OFDMA) and single-carrier frequency-division multiple access (SC-FDMA) which have received attention in recent years as physical layer protocol in WiMAX and 3GPP Long Term Evolution (LTE) and analyze the effect of the transmitter (Tx) IQIs on OFDMA and SC-FDMA receivers. To cope with the interuser interference problem due to Tx IQIs, we propose a widely linear receiver for OFDMA and SC-FDMA systems and also propose a novel subcarrier allocation scheme, which has high tolerance to such Tx IQ distortion.