sep_8_4_awgn.m

用MATLAB对QAM进行仿真计算（32QAM）

% function ps=ps(r,snr_db)Average SEP for 8*4 QAM in AWGN for different
% rations r=dQ/dI
% σ^2=1;σn^2=1;ai=di/σn;aq=dq/σn;r=dq/di;
clear all;close all;clc;
MI=8;
MQ=4;
M1=1-1/MI;
M2=1-1/MQ;
r=[1,sqrt(21/5),21/5];
SNR_dB=15:1:35;
SNR=10.^(SNR_dB./10);
AI1=sqrt(SNR./(21+5.*r(1).^2));
AQ1=r(1).*AI1;
AI2=sqrt(SNR./(21+5.*r(2).^2));
AQ2=r(2).*AI2;
AI3=sqrt(SNR./(21+5.*r(3).^2));
AQ3=r(3).*AI3;
   %r=1
Ps_1=2.*M1.*Q_x(AI1)+2.*M2.*Q_x(AQ1)-4.*M1*M2.*Q_x(AI1).*Q_x(AQ1);
   %r=sqrt(21/5)
Ps_2=2.*M1.*Q_x(AI2)+2.*M2.*Q_x(AQ2)-4.*M1.*M2.*Q_x(AI2).*Q_x(AQ2);
   %r=21/5
Ps_3=2.*M1.*Q_x(AI3)+2.*M2.*Q_x(AQ3)-4.*M1.*M2.*Q_x(AI3).*Q_x(AQ3);
semilogy(SNR_dB,Ps_1,'-');
hold on;
semilogy(SNR_dB,Ps_2,'--');
semilogy(SNR_dB,Ps_3,'.');
legend('r=1','r=(21/5)^{1/2}','r=21/5');
axis([15,35,1e-7,1]);
xlabel('10log_{10}(E_{T}^{AWGN}/\sigma_{n}^2)');
ylabel('SEP');
grid on;