matlab AWGN仿真

N=10; aqam=[-3 -1 1 3 ]; A=repmat(aqam,4,1); B=flipud(A'); konst_qam=A+j*B;% 8x8-Matrix that contains all the constellation points. qam=konst_qam(randint(N,1,16)+1) % 16-QAM symbol sequence plot(qam,'o'); % QAM-constellation in the transmitter-end signal_bpsk=floor(rand(1,N)*2)*2-1; konst_qpsk=exp(j*[pi/4 3*pi/4 5*pi/4 7*pi/4]).'; qpsk=konst_qpsk(randint(N,1,4)+1); plot(qpsk,'o'); n=randn(size(qam))+j*randn(size(qam)); svqpsk=std(qpsk)^2; svqam=std(qam)^2; nv=std(n)^2; SNR=20; p1=std(qpsk)/(std(n)*10^(SNR/20)); snqpsk=qpsk+n*p1; subplot(4,2,1); plot(snqpsk,'o'); title('QPSK SNR=20'); p2=std(qam)/(std(n)*10^(SNR/20)); snqam=qam+n*p2; subplot(4,2,2); plot(snqam,'o'); title('QAM SNR=20'); SNR=15; p1=std(qpsk)/(std(n)*10^(SNR/20)); snqpsk=qpsk+n*p1; subplot(4,2,3); plot(snqpsk,'o'); title('QPSK SNR=15'); p2=std(qam)/(std(n)*10^(SNR/20)); snqam=qam+n*p2; subplot(4,2,4); plot(snqam,'o'); title('QAM SNR=15'); SNR=10; p1=std(qpsk)/(std(n)*10^(SNR/20)); snqpsk=qpsk+n*p1; subplot(4,2,5); plot(snqpsk,'o'); title('QPSK SNR=10'); p2=std(qam)/(std(n)*10^(SNR/20)); snqam=qam+n*p2; subplot(4,2,6); plot(snqam,'o'); title('QAM SNR=10'); SNR=5; p1=std(qpsk)/(std(n)*10^(SNR/20)); snqpsk=qpsk+n*p1; subplot(4,2,7); plot(snqpsk,'o'); title('QPSK SNR=5'); p2=std(qam)/(std(n)*10^(SNR/20)); snqam=qam+n*p2; subplot(4,2,8); plot(snqam,'o'); title('QAM SNR=5'); sn_block=repmat(snqpsk,1,4).'; konst_block=repmat(konst_qpsk,1,N); distance=abs(sn_block-konst_block); [y,ind_1]=min(distance); qpsk_det=konst_qpsk(ind_1); sn_block=repmat(snqam,1,16).'; konst_qam2=konst_qam(:); konst_block=repmat(konst_qam2,1,N); distance=abs(sn_block-konst_block); [y,ind_1]=min(distance); qam_det=konst_qam2(ind_1)