Joint blind equalization and detection of QAM and PAM transmissions

A simple method for joint blind equalization and detection of QAM and PAM transmissions is presented. By studying the geometrical relations between the rectangular QAM signal constellation and PAM signal constellation, a novel cost function including blind equalization and detection of them is defined. Such cost function-based the improved constant modulus algorithm (CMA) transforms the coordinates of outputs from equalizer and guide the new coordinates of them to locate on the unit circle. It will go to zero when the channel is perfectly equalized which results in faster convergence rate and lower steady state mean square error (MSE). Furthermore the more attractive performance of it is that it can achieve the detection of QAM and PAM signals without any priori statistical information of them. So the proposed method can be used in some special fields such as military field threat evaluation, electronic counter measures and many others. Simulation results show that the proposed method achieves satisfactory performance.