I/Q imbalance in MIMO STBC communication systems: Impact and solution

In this work we study the performance degradation caused by the in-phase/quadrature (I/Q) imbalance of the transceivers in multiple-input multiple-output (MIMO) space-time block coded (STBC) communication systems. The 2-Tx orthogonal STBC (OSTBC) systems, 4-Tx quasi-orthogonal STBC (QOSTBC) systems, and 4-Tx rotated QOSTBC (RQOSTBC) systems in the presence of I/Q imbalance are studied in detail. Our work shows that I/Q imbalance causes severe distortion in MIMO STBC communication systems. By exploiting the structure of the received signal, low-complexity solutions are proposed to mitigate the distortion caused by I/Q imbalance successfully.