1、=7); x1(i)=1; else x1(i)=-1; endendt1=0:8-0.01;t2=0:7-0.01;t3=-1:7.1-0.01;t4=0:8.1-0.01;tt1=length(t1);x2=ones(1,800);tt1 if (t1(i)=0 & t1(i)=4&=8); x2(i)=1; else x2(i)=-1;f=0:0.1:1;xrc=0.5+0.5*cos(pi*f);y1=conv(x1,xrc)/5.5;y2=conv(x2,xrc)/5.5;n0=randn(size(t2);f1=1;i=x1.*cos(2*pi*f1*t);q=x2.*sin(2*
2、pi*f1*t1);I=i(101:800);Q=q(1:700);QPSK=sqrt(1/2).*I+sqrt(1/2).*Q;QPSK_n=(sqrt(1/2).*I+sqrt(1/2).*Q)+n0;n1=randn(size(t2);i_rc=y1.*cos(2*pi*f1*t3);q_rc=y2.*sin(2*pi*f1*t4);I_rc=i_rc(101:Q_rc=q_rc(1:QPSK_rc=(sqrt(1/2).*I_rc+sqrt(1/2).*Q_rc);QPSK_rc_n1=QPSK_rc+n1;figure(1)subplot(4,1,1);plot(t3,i_rc);a
3、xis(-1 8 -1 1);ylabel(a序列);subplot(4,1,2);plot(t4,q_rc);b序列subplot(4,1,3);plot(t2,QPSK_rc);合成序列subplot(4,1,4);plot(t2,QPSK_rc_n1);加入噪声效果图:% 设定 T=1,加入高斯噪声% 调制bit_in = randint(1e3, 1, 0 1);bit_I = bit_in(1:2:1e3);bit_Q = bit_in(2:data_I = -2*bit_I+1;data_Q = -2*bit_Q+1;data_I1=repmat(data_I,20,1);data
4、_Q1=repmat(data_Q1e4 data_I2(i)=data_I1(i); data_Q2(i)=data_Q1(i);end;data_I2_rc=conv(data_I2,xrc)/5.5;data_Q2_rc=conv(data_Q2,xrc)/5.5;t1=0:1e3+0.9;n0=rand(size(t1);I_rc=data_I2_rc.*cos(2*pi*f1*t1);Q_rc=data_Q2_rc.*sin(2*pi*f1*t1);QPSK_rc_n0=QPSK_rc+n0;% 解调I_demo=QPSK_rc_n0.*cos(2*pi*f1*t1);Q_demo=
5、QPSK_rc_n0.*sin(2*pi*f1*t1);% 低通滤波I_recover=conv(I_demo,xrc);Q_recover=conv(Q_demo,xrc);I=I_recover(11:10010);Q=Q_recover(11:0.05:1e3-0.05;t3=0:1e3-0.1;% 抽样判决data_recover=;20:10000 data_recover=data_recover I(i:1:i+19) Q(i:i+19);bit_recover=;20000 if sum(data_recover(i:i+19) data_recover_a(i:i+19)=1
6、; bit_recover=bit_recover 1; elsei+19)=-1; bit_recover=bit_recover -1;error=0;dd = -2*bit_in+1;ddd=dd;ddd1=repmat(ddd,20,1);2e4 ddd2(i)=ddd1(i);1e3 if bit_recover(i)=ddd(i) error=error+1;p=error/1000;subplot(2,1,1);plot(t2,ddd2);axis(0 100 -2 2);title(原序列subplot(2,1,2);plot(t2,data_recover_a);解调后序列%
7、 设定 T=1, 不加噪声t=0:I_demo=QPSK_rc.*cos(2*pi*f1*t1);Q_demo=QPSK_rc.*sin(2*pi*f1*t1);ddd = -2*bit_in+1;ddd1=repmat(ddd,10,1);plot(t3,I);axis(0 20 -6 6);plot(t3,Q);plot(t2,data_recover);plot(t,ddd2);% QPSK误码率分析SNRindB1=0:10;SNRindB2=0:length(SNRindB1) pb,ps=cm_sm32(SNRindB1(i); smld_bit_err_prb(i)=pb; sm
8、ld_symbol_err_prb(i)=ps;length(SNRindB2) SNR=exp(SNRindB2(i)*log(10)/10); theo_err_prb(i)=Qfunct(sqrt(2*SNR);QPSK误码率分析semilogy(SNRindB1,smld_bit_err_prb,*axis(0 10 10e-8 1);hold on;% semilogy(SNRindB1,smld_symbol_err_prb,osemilogy(SNRindB2,theo_err_prb);legend(仿真比特误码率,理论比特误码率hold off;functiony=Qfunc
9、t(x)y=(1/2)*erfc(x/sqrt(2);functionpb,ps=cm_sm32(SNRindB)N=10000;E=1;SNR=10(SNRindB/10);sgma=sqrt(E/SNR)/2;s00=1 0;s01=0 1;s11=-1 0;s10=0 -1;N temp=rand; if (temp0.25) dsource1(i)=0; dsource2(i)=0; elseif (temp0.5) dsource2(i)=1;0.75) dsource1(i)=1; else end;numofsymbolerror=0;numofbiterror=0; n=sgm
10、a*randn(size(s00); if(dsource1(i)=0)&(dsource2(i)=0) r=s00+n; elseif(dsource1(i)=0)&(dsource2(i)=1) r=s01+n; elseif(dsource1(i)=1)& r=s10+n; r=s11+n; c00=dot(r,s00); c01=dot(r,s01); c10=dot(r,s10); c11=dot(r,s11); c_max=max(c00 c01 c10 c11); if (c00=c_max) decis1=0;decis2=0; elseif(c01=c_max)decis2=1; elseif(c10=c_max) decis1=1; symbolerror=0; if(decis1=dsource1(i) numofbiterror=numofbiterror+1; symbolerror=1; if(decis2=dsource2(i) if(symbolerror=1) numofsymbolerror=numofsymbolerror+1;ps=numofsymbolerror/N;pb=numofbiterror/(2*N);
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