Performance of finite-resolution receivers for M-QAM systems with IQ imbalances

In the paper, we concentrate on investigating the effect of imbalances between In-phase(I) and Quadrature-phase(Q) branches in high-order quadrature amplitude modulation (QAM) systems with finite resolution. We find that the zero intermediate frequency (zero-IF) receiver can't handle the IQ imbalances even with the full resolution (FR) when the order of QAM is pretty high, e.g. 64, 256. Instead, the digital intermediate frequency (digital-IF) receiver can provide an acceptable performance.