Digital Compensation of Tx/Rx I/Q Imbalance in TD-SCDMA Systems

TD-SCDMA (Time Division-Synchronous CDMA) systems show performance degradation due to I/Q imbalance resulting from direct-conversion transmitters and receivers. In overall system analysis, it is important to consider both transmitter and receiver I/Q imbalances to account for low cost base stations (BS's) such as femtocells. Two approaches are considered in this paper. The first one is a purely time-domain approach based on widely linear minimum mean square error estimation (WL-MMSE). The second one is a frequency-domain approach with reduced computational complexity. Simulation studies are performed and comparison results presented.