US Patent 7154966 Method and system for M-QAM detection in communication systems

A method and system are described for performing fast and simple M-QAM detection on received signals, such as a 16-QAM signal, by estimating M-QAM symbol constellation decision boundaries. Amplitude information is collected for in-phase and quadrature phase components of the received signal over a number of symbols. An average of the absolute value of the amplitude information of the in-phase components and of the quadrature phase components is determined over the number of symbols. The determined average absolute values of the in-phase and quadrature phase components provide a reference to produce the decision boundary estimates. Bias compensation may optionally be applied to the decision boundary estimates based on the estimated signal-to-interference ratio (“SIR”) of the received signal to produce bias corrected decision boundary estimates.