%29/8/2008 ZHANGSONG%根據論文《AF三跳協作分集...》編寫仿真程序%===========================================function BER=AF3(Dsd,Ds1,D12,D2d)Qsd=sqrt(10^(Dsd/10));Qs1=sqrt(10^(Ds1/10));Q12=sqrt(10^(D12/10));Q2d=sqrt(10^(D2d/10)); N=10240;max_snr=25;BER=zeros(1,max_snr);ber=zeros(1,max_snr);for SNR=0:max_snr    %噪聲歸一化    N0=1/(10^(SNR/10)); %N0為方差    x=rand(1,N)>0.5;    X=QpskMapping(x);    Xd=[];    M=length(X);    for i=1:M        %產生高斯白噪聲        Nsd=sqrt(N0)*(randn+j*randn);        Ns1=sqrt(N0)*(randn+j*randn);        N12=sqrt(N0)*(randn+j*randn);        N2d=sqrt(N0)*(randn+j*randn);        %信道增益        Hsd=Qsd*(randn+j*randn);        Hs1=Qs1*(randn+j*randn);        H12=Q12*(randn+j*randn);        H2d=Q2d*(randn+j*randn);        %優化功率分配算法        %=============================        A=(Q2d+Q12)^2*Q12*Qs1^2;        B=Q2d^2*Q12^3;        if A~=B            Es=(A-4*B+sqrt(A^2+8*A*B))/(4*(A-B));        else            Es=2/3;        end        E1=Q2d/(Q2d+Q12)*(1-Es);        E2=1-E1-Es;        %===============================        %協作節點的放大增益        %===============================        B1=sqrt(E1/(Es*Hs1^2+N0));        B2=sqrt(E2/(E1*H12^2+N0));        %===============================        %最大合并比加權因子計算        A0=sqrt(Es)*conj(Hsd)/N0;        A1=sqrt(Es)*B1*B1*conj(Hs1)*conj(H12)*conj(H2d)/...            (B1^2*B2^2*abs(H12)^2*abs(H2d)^2+B2^2*abs(H2d)^2+1)/N0;        %接收信號        Y1=sqrt(Es)*X(i)*Hs1+Ns1;        Y2=B1*Y1*H12+N12;       % Y=A0*(sqrt(Es)*X(i)*Hsd+Nsd)+A1*(B2*Y2*H2d+N2d);        Y=A0*(sqrt(Es)*X(i)*Hsd+Nsd)+A1*(B2*Y2*H2d+N2d);        %解調        dh = [1+j -1+j -1-j 1-j]/sqrt(2);        D1=abs(Y*[1 1 1 1]-dh).^2;        [minScale1 positionmin1]=min(D1);        Xd=[Xd dh(positionmin1)];    end    xd=QpskInverseMapping(Xd);    err1=(x==xd);    tot_err1=0;     for i=1:N        if err1(i)==0           tot_err1=tot_err1+1;        end     end     BER(SNR+1)=tot_err1/N;%理論值ber(SNR+1)=(3/8)*N0^2*(1/(Es^2*Qsd^2*Qs1^2)+1/(Es*E1*Qsd^2*Q12^2)+1/(Es*E2*Qsd^2*Q2d^2));end%semilogy(0:max_snr,BER,'r');%hold onsemilogy(0:max_snr,ber);