ostbcr1-2.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
    max_snr=15;%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+1);
    tot_err_symbol =zeros(1,max_snr+1);
    tot_err_bit=zeros(1,max_snr+1);
   for snr=0:max_snr 
           sig =sqrt(4/(10^(snr/10))); 
         while tot_err_symbol(snr+1)<10000
             tot_frame_tx(snr+1) = tot_frame_tx(snr+1)+1;
             bit_sequence = rand(1,symbol_per_frame * 2)>0.5;        %生成伪随机二进制待发送序列
             qpsk_sequence = QpskMapping(bit_sequence); %二进制信道与QPSK信号的转换
           %归一化的噪声能量       
            addtional_gaussian_noise =sig * (randn(Nr,2*Nt,symbol_per_frame/4) + j*randn(Nr,2*Nt,symbol_per_frame/4))/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
                M=1;
                X=[qpsk_sequence(k) -qpsk_sequence(k+1) -qpsk_sequence(k+2) -qpsk_sequence(k+3) conj(qpsk_sequence(k)) -conj(qpsk_sequence(k+1)) -conj(qpsk_sequence(k+2)) -conj(qpsk_sequence(k+3)); 
                   qpsk_sequence(k+1) qpsk_sequence(k) qpsk_sequence(k+3) -qpsk_sequence(k+2) conj(qpsk_sequence(k+1))  conj(qpsk_sequence(k)) conj(qpsk_sequence(k+3)) -conj(qpsk_sequence(k+2));
                   qpsk_sequence(k+2) -qpsk_sequence(k+3) qpsk_sequence(k) qpsk_sequence(k+1) conj(qpsk_sequence(k+2)) -conj(qpsk_sequence(k+3)) conj(qpsk_sequence(k)) conj(qpsk_sequence(k+1));
                   qpsk_sequence(k+3) qpsk_sequence(k+2) -qpsk_sequence(k+1) qpsk_sequence(k) conj(qpsk_sequence(k+3)) conj(qpsk_sequence(k+2)) -conj(qpsk_sequence(k+1)) conj(qpsk_sequence(k));];
                R=H*X+addtional_gaussian_noise(:,:,M);  %接收信号
                M=M+1;      
                x1=R(1,1)*conj(H(1,1))+R(1,2)*conj(H(1,2))+R(1,3)*conj(H(1,3))+R(1,4)*conj(H(1,4))+conj(R(1,5))*H(1,1)+conj(R(1,6))*H(1,2)+conj(R(1,7))*H(1,3)+conj(R(1,8))*H(1,4) ;   
                x2=R(1,1)*conj(H(1,2))-R(1,2)*conj(H(1,1))-R(1,3)*conj(H(1,4))+R(1,4)*conj(H(1,3))+conj(R(1,5))*H(1,2)-conj(R(1,6))*H(1,1)-conj(R(1,7))*H(1,4)+conj(R(1,8))*H(1,3) ;
                x3=R(1,1)*conj(H(1,3))+R(1,2)*conj(H(1,4))-R(1,3)*conj(H(1,1))-R(1,4)*conj(H(1,2))+conj(R(1,5))*H(1,3)+conj(R(1,6))*H(1,4)-conj(R(1,7))*H(1,1)-conj(R(1,8))*H(1,2);
                x4=R(1,1)*conj(H(1,4))-R(1,2)*conj(H(1,3))+R(1,3)*conj(H(1,2))-R(1,4)*conj(H(1,1))+conj(R(1,5))*H(1,4)-conj(R(1,6))*H(1,3)+conj(R(1,7))*H(1,2)-conj(R(1,8))*H(1,1);
                dh = [1+j -1+j -1-j 1-j]/sqrt(2);
                D1=abs((x1/8)*[1 1 1 1]-dh).^2;
                [minnumber1 position1]=min(D1);%求出最小的距离
                X1=dh(position1);             %估计出x1的值
                D2=abs((x2/8)*[1 1 1 1]-dh).^2;
                [minnumber1 position2]=min(D2);
                X2=dh(position2);
                D3=abs((x3/8)*[1 1 1 1]-dh).^2;
                [minnumber1 position3]=min(D3);
                X3=dh(position3);
                D4=abs((x4/8)*[1 1 1 1]-dh).^2;
                [minnumber1 position4]=min(D4);
                X4=dh(position4);
                if(X(1,1)~=X1)  %计算自然循序mapping时bit错误的个数
                     tot_err_symbol(snr+1)=tot_err_symbol(snr+1)+1;
                   if((X(1,1)+X1)*sqrt(2)==2|(X(1,1)+X1)*sqrt(2)==-2)
                    tot_err_bit(snr+1)=tot_err_bit(snr+1)+2;
                   else
                          tot_err_bit(snr+1)=tot_err_bit(snr+1)+1; 
                     end
                  end
                 if(X(2,1)~=X2)
                      tot_err_symbol(snr+1)=tot_err_symbol(snr+1)+1;
                    if((X(2,1)+X2)*sqrt(2)==2|(X(2,1)+X2)*sqrt(2)==-2)
                    tot_err_bit(snr+1)=tot_err_bit(snr+1)+2;
                     else
                      tot_err_bit(snr+1)=tot_err_bit(snr+1)+1; 
                    end   
                 end
                  if(X(3,1)~=X3)
                      tot_err_symbol(snr+1)=tot_err_symbol(snr+1)+1;
                    if((X(3,1)+X3)*sqrt(2)==2|(X(3,1)+X3)*sqrt(2)==-2)
                    tot_err_bit(snr+1)=tot_err_bit(snr+1)+2;
                     else
                      tot_err_bit(snr+1)=tot_err_bit(snr+1)+1; 
                    end   
                 end
                  if(X(4,1)~=X4)
                      tot_err_symbol(snr+1)=tot_err_symbol(snr+1)+1;
                    if((X(4,1)+X4)*sqrt(2)==2|(X(4,1)+X4)*sqrt(2)==-2)
                    tot_err_bit(snr+1)=tot_err_bit(snr+1)+2;
                     else
                      tot_err_bit(snr+1)=tot_err_bit(snr+1)+1; 
                    end   
                 end
     
                % if(X(1,1)~=X1)    %计算Gray码mapping时bit错误的个数
                %     if((X(1,1)+X1)==0)
                 %   Gray_tot_err_bit(snr+1)=Gray_tot_err_bit(snr+1)+2;
                 %    else
                 %     Gray_tot_err_bit(snr+1)=Gray_tot_err_bit(snr+1)+1; 
                 %     end
                 % end      
                % if(X(2,1)~=X2)
                %     if((X(2,1)+X2)==0)
                %    Gray_tot_err_bit(snr+1)=Gray_tot_err_bit(snr+1)+2;
                %      else
                %      Gray_tot_err_bit(snr+1)=Gray_tot_err_bit(snr+1)+1; 
                %      end
                %  end
               
           end
        end
    end        
    %在不同信噪比条件下，求系统SER和BER
    ser_snr=tot_err_symbol./(tot_frame_tx * symbol_per_frame) ;
    ber_snr=tot_err_bit./(tot_frame_tx * symbol_per_frame*2);
    figure(1);
   semilogy(0:max_snr,ser_snr,'-o');
    grid
    hold on
    semilogy(0:max_snr,ber_snr,'-*');
    xlabel('SNR');
    ylabel('Error Ratio');
    legend('SER-SNR','BER-SNR');
    title('Ideal CSI');
    hold off