jafarkhani.m

MIMO-有关差分编码,用matlab书写,

    Nt=4;%发射天线数为4
    Nr=1;%接收天线数为1
    min_snr=5;
    max_snr=35;%最大的信噪设定为15
    symbol_per_frame=120;%每一帧的符号数为120个
    tot_frame_tx=zeros(1,(max_snr-min_snr)/2+1);
    tot_err_bit=zeros(1,(max_snr-min_snr)/2+1);
   for snr=min_snr:2:max_snr
       display(snr);
        for ii=1:50000
            D1=zeros(1,16);
            D2=zeros(1,16);
             tot_frame_tx((snr-min_snr)/2+1) = tot_frame_tx((snr-min_snr)/2+1)+1;
             bit_sequence = rand(1,symbol_per_frame * 3)>0.5;        %生成伪随机二进制待发送序列
             qpsk_sequence =  Eightpsk(bit_sequence); %二进制信道与QPSK信号的转换
            sig =sqrt(4/(10^(snr/10)));  %归一化的噪声能量       
            addtional_gaussian_noise =sig * (randn(Nr,Nt,symbol_per_frame)/sqrt(2) + j*randn(Nr,Nt,symbol_per_frame)/sqrt(2)); %生成加性高斯噪声
            H=RayleighCH(Nr,Nt); %生成具有瑞利分布特性的信道衰落系数
            for k=1:4:symbol_per_frame-3
                X=[qpsk_sequence(k) -conj(qpsk_sequence(k+1)) -conj(qpsk_sequence(k+2)) qpsk_sequence(k+3); 
                   qpsk_sequence(k+1) conj(qpsk_sequence(k)) -conj(qpsk_sequence(k+3))  -qpsk_sequence(k+2);
                   qpsk_sequence(k+2) -conj(qpsk_sequence(k+3)) conj(qpsk_sequence(k))  -qpsk_sequence(k+1);
                   qpsk_sequence(k+3) conj(qpsk_sequence(k+2))  conj(qpsk_sequence(k+1)) qpsk_sequence(k) ;];
                R=H*X+addtional_gaussian_noise(:,:,k);         %接收信号
                a1=-conj(R(1,1))*H(1,1)-R(1,2)*conj(H(1,2))-R(1,3)*conj(H(1,3))-conj(R(1,4))*H(1,4);   
                b1=-conj(R(1,1))*H(1,4)+R(1,2)*conj(H(1,3))+R(1,3)*conj(H(1,2))-conj(R(1,4))*H(1,1);
                c1=H(1,1)*conj(H(1,4))-conj(H(1,2))*H(1,3)-H(1,2)*conj(H(1,3))+conj(H(1,1))*H(1,4);
                a2=-conj(R(1,1))*H(1,2)+R(1,2)*conj(H(1,1))-R(1,3)*conj(H(1,4))+conj(R(1,4))*H(1,3);   
                b2=-conj(R(1,1))*H(1,3)-R(1,2)*conj(H(1,4))+R(1,3)*conj(H(1,1))+conj(R(1,4))*H(1,2);
                c2=H(1,2)*conj(H(1,3))-conj(H(1,1))*H(1,4)-H(1,1)*conj(H(1,4))+conj(H(1,2))*H(1,3);
                d=abs(H(1,1))^2+abs(H(1,2))^2+abs(H(1,3))^2+abs(H(1,4))^2;
               
           dh = [1 (1+j)/sqrt(2)  j  (-1+j)/sqrt(2)   -1   (-1-j)/sqrt(2)   -j   (1-j)/sqrt(2);];
               m=1;
                  for L=1:8
                      for LL=1:8 
                 D1(m,1)=d*(abs(dh(1,L))^2+abs(dh(1,LL))^2)+2*real(a1*dh(1,L)+b1*dh(1,LL)+c1*dh(1,L)*conj(dh(1,LL)));
                 D1(m,2)=L;
                 D1(m,3)=LL;
                 m=m+1;
                  end
              end
              [minnumber1 position1]=min(D1(:,1));%求出最小的距离
                X1=dh(D1(position1,2));  %估计出x1的值
                X4=dh(D1(position1,3));  %估计出x2的值
                m=1;
                  for L=1:8
                      for LL=1:8     
                 D2(m,1)=d*(abs(dh(1,L))^2+abs(dh(1,LL))^2)+2*real(a2*dh(1,L)+b2*dh(1,LL)+c2*dh(1,L)*conj(dh(1,LL)));
                 D2(m,2)=L;
                 D2(m,3)=LL;
                 m=m+1;
                  end
              end
               [minnumber2 position2]=min(D2(:,1));%求出最小的距离
                X2=dh(D2(position2,2));  %估计出x1的值
                X3=dh(D2(position2,3));  %估计出x2的值
            
                if(X(1,1)~=X1)  %计算Gray  mapping时bit错误的个数
                          tot_err_bit((snr-min_snr)/2+1)=tot_err_bit((snr-min_snr)/2+1)++table(X(1,1),X1); 
                  end
                  
                 if(X(2,1)~=X2)  %计算Gray mapping时bit错误的个数
                          tot_err_bit((snr-min_snr)/2+1)=tot_err_bit((snr-min_snr)/2+1)++table(X(2,1),X2); 
                  end
                  
                    if(X(3,1)~=X3)  %计算Gray mapping时bit错误的个数
                    tot_err_bit((snr-min_snr)/2+1)=tot_err_bit((snr-min_snr)/2+1)++table(X(3,1),X3);
                  end
                  
                  if(X(4,1)~=X4)
                      tot_err_bit((snr-min_snr)/2+1)=tot_err_bit((snr-min_snr)/2+1)++table(X(4,1),X4);   
                 end
                 
                 
             end
        end
    end        
    %在不同信噪比条件下，求系统SER和BER
    ber_snr=tot_err_bit./(tot_frame_tx * symbol_per_frame*3);
    figure(1);
    semilogy(min_snr:2:max_snr,ber_snr,'-*');
     grid
    xlabel('SNR');
    ylabel('Error Ratio');
    legend('SER-SNR','BER-SNR');
    title('Ideal CSI');