Multi-User SC-FDMA Systems under IQ Imbalance: EVM and Subcarrier Mapping Impact

In this paper, we derive an analytical expression for the error vector magnitude (EVM) under joint transmit-receive Inphase-Quadrature imbalance (IQI). IQI is a major radio frequency impairment in direct- conversion transceivers. We consider multi-user uplink transmission with single-carrier frequency- division-multiple access as in the long-term evolution standard. The derived EVM expression reveals an interesting relationship between the spectral allocation of a user´s subcarriers and the immunity of this user to IQI. Furthermore, we verify the accuracy of our derived EVM expression through Monte-Carlo simulations for various IQI levels.