M-QAM Signal Recognition based on Clustering Analysis

By comparing and analyzing different clustering algorithms for M-ary quadrature amplitude modulation(M-QAM)signals recognition,and for the problem of insufficient symbols,an improved algorithm based on symmetrical characteristics of constellation and subtractive clustering is proposed.Symbol rate is estimated first form the received data,and based on the estimation,and through matched filtering and sampling judgment the signal constellation is recovered;then abscissa and ordinate values of the constellation points in two quadrants which are symmetric about the origin are projected onto the axes;and finally,the M-QAM signals are identified through clustering the projected points.Simulation results show that the improved method could identify the M-QAM signals correctly and effectively while saving the computing time.So this algorithm is easy and convenient in practical application.