I/Q imbalance mitigation for STBC MIMO-OFDM communication systems

Abstract

In this work we study the performance degradation caused by the in-phase/quadrature (I/Q) imbalance in space-time block coded (STBC) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication systems. The 2-Tx Alamouti scheme, 4-Tx quasi- orthogonal STBC (QOSTBC) scheme, and 4-Tx rotated QOSTBC (RQOSTBC) scheme with I/Q imbalance are examined in details. Our study shows that I/Q imbalance causes severe distortion in STBC MIMO-OFDM systems. By exploiting the structure of the received signal, low-complexity solutions are developed to mitigate the resultant distortion successfully.