Maximum likelihood detection of I/Q imbalance signal with self-organized clustering assistance

For the detection of a quadrature phase shift keying (QPSK) modulated signal, in the presence of I/Q imbalance, maximum likelihood detection with self-organized clustering assistance (ML-SOCA) is proposed in this paper. In modulation techniques employed in a quadrature receiver, gain and phase imbalance between I and Q channel filters and amplifiers can cause asymmetry and rotation in signal constellations, then the probability of error moves far away from the ideal point. The self-organized clustering system is used to learn the behavior of the received signals and estimate the new decision boundaries that are fed to the maximum likelihood detector. Simulation results were obtained with Matlab.