Frequency domain iq imbalance correction scheme for orthogonal frequency division multiplexing (OFDM) systems

Future, high bit rate communication systems tolerate very little error in the modulation. This means that conventionally negligible error sources like the imbalance between the in-phase (I) and quadrature (Q) branches of the receiver can start limiting the performance of the system. This is especially true when at the same time cheaper, smaller, more robust and more versatile analog front ends are required from the RF designers. This paper describes the sources and the effect of the IQ imbalance as well as a new method for correcting the error due to the imbalance in Orthogonal Frequency Division Multiplexing (OFDM) systems. The described method can correct both constant and frequency dependent imbalance by using the pilot signals of the transmission to detect the imbalance so little computational power is required compared to the decision aided methods.