M = 16; %M進制
x = randint(5000,1,M);
y=modulate(modem.qammod(M),x);   %調制
ynoisy = awgn(y,15,'measured');   %加噪聲
scatterplot(y);
scatterplot(ynoisy);
z=demodulate(modem.qamdemod(M),ynoisy);  %解調
[num,rt]= symerr(x,z)  %計算誤比特率