myselfchase_soft.m

是一个四发四收的球型译码程序

        %==========================================
%16QAM;   1/2,3conv;    TX=4;RX=4;  硬判决
%==========================================
clc;
clear
Tx=4;
Rx=4;
M=16;
h=modem.qammod(M);
h2=modem.qamdemod(M);
Factor=10;
Table_bit=zeros(M,log2(M));
for i=2:M
    Table_bit(i,:)=de2bi(i-1,log2(M));
end
%Ch_Q=[1.65 2.3 3.25 5 7.6 11.55 18];
Ch_Q=1.65;

%L=input('please enter the length of the frame:');
%SNRdB=input('please enter SNR:');
%lenl=input('please enter the length of bit:');
SNRdB=8;
lenl=96;
%len=96*10;
L=1;
%SNRdB=5;
Num_order=M;
for SNRindex=1:length(SNRdB)
    SNRtemp=10.^((SNRdB+3)/10);
    SNR=SNRtemp(SNRindex);
    sigma_n2=sqrt(Tx)/sqrt(SNR);
    len=lenl(SNRindex);
    msg=randint(len,1);
    trel=poly2trellis(3,[6,7]);
    code=convenc(msg,trel);
    y=randintrlv(code,4831);
    Sig_code=buffer(y,Tx*L*log2(M));
    Sym_code=zeros(Tx*L*log2(M),2*len/(Tx*L*log2(M)));
      
    for BloInd=1:2*len/(Tx*L*log2(M))
        % transmit signal
        TxMatrix_bit_src=Sig_code(:,BloInd);
        TxMatrix_bit_map=reshape(TxMatrix_bit_src,Tx*L,log2(M));
        TxMatrix_sym_temp=bi2de(TxMatrix_bit_map);
        TxMatrix_sym=modulate(h,TxMatrix_sym_temp)/sqrt(Factor);
        TxMatrix=reshape(TxMatrix_sym,Tx,L);
      
        %channel
        for i=1:Rx
            Ch=(randn(Tx,L)+sqrt(-1)*randn(Tx,L)).*sqrt(0.5);
            TxPassCh=Ch.*TxMatrix;
            TxSum_temp=sum(TxPassCh);
            for k=1:L
                Ch_Equ(Rx*(k-1)+i,Tx*(k-1)+1:Tx*k)=(Ch(:,k)).';
            end
            Tx_Sum(i,:)=TxSum_temp;
         end
 
          % receive signal 
          RxSig=Tx_Sum+sigma_n2*(randn(Rx,L)+sqrt(-1)*randn(Rx,L))/sqrt(2);
          RxSig_MF=reshape(RxSig,Rx*L,1);
          Ch_Total=Ch_Equ; 
            
          %[BLR,DeSymb,ind]=LLR1Layer(RxSig_MF,Ch_Total,M,sigma_n2,1,2);
           [BLR,DeSymb,IX]=LLRnLayer(RxSig_MF,Ch_Total,M,sigma_n2,1,2,1);
           ind=IX(1);
           ChanCoeff=Ch_Total(:,ind);
           Chan=horzcat(Ch_Total(:,1:ind-1),Ch_Total(:,ind+1:Tx));
           DetSignal=demodulate(h2,sqrt(Factor)*[DeSymb(ind,1)]);
           Det_bit=de2bi(DetSignal,log2(M),2);
           Bit_Vec=reshape(Det_bit,log2(M),1);
           Table_pertur=zeros(Num_order,log2(M));
           Phi=zeros(Num_order,1);
           Temp_Ind=0;
           for i=1:Num_order
               Table_pertur(i,:)=xor(Table_bit(i,:),Bit_Vec.');
               Phi(i)=Phi(i)+Table_pertur(i,1:log2(M))*abs(BLR(1,1:log2(M)).');
               if Phi(i)<=Ch_Q(SNRindex)
                  Temp_Ind=Temp_Ind+1;
                  IndSet(Temp_Ind)=i;
               end
           end
            
           IndSet=IndSet(:,1:Temp_Ind);
           MLValue0=zeros(Tx*L*log2(M),1);
           MLValue1=zeros(Tx*L*log2(M),1);                      
           for i=1:Temp_Ind 
               Search_bit=Table_bit(IndSet(i),:);
               DetBitMap=reshape(Search_bit,1,log2(M));
               OrgSymb=bi2de(DetBitMap); 
               Sym1=modulate(h,OrgSymb)/sqrt(Factor);
               % cacellating the interference caused by current detected signal
               ReSig=RxSig_MF-ChanCoeff.*Sym1;
               Det_sig_temp=MIMONCZF(ReSig,Chan,M,sigma_n2,Factor,0);
               DetTemp=vertcat(Det_sig_temp(1:ind-1,1),OrgSymb(1,1),Det_sig_temp(ind:Tx-1,1));
               Tx_sym=modulate(h,DetTemp)/sqrt(Factor);
               Tx_sym_1=reshape(Tx_sym,Tx,L);
               Sigma=2*sigma_n2*sigma_n2;
               Det_bit=de2bi(DetTemp,log2(M),2);
               dd_bit=reshape(Det_bit,Tx*L*log2(M),1);
               for j=1:Tx*L*log2(M)
                   if dd_bit(j,1)==0                    
                      MLValue0(j,1)=MLValue0(j,1)+exp(-norm(RxSig-Ch_Total*Tx_sym_1,'fro')^2/Sigma);   
                   else
                      MLValue1(j,1)=MLValue1(j,1)+exp(-norm(RxSig-Ch_Total*Tx_sym_1,'fro')^2/Sigma);
                   end
               end
           end            
            %LLR(j)=log(MLValue1/MLValue0);
            NormFactor=sqrt(MLValue1.*MLValue1+MLValue0.*MLValue0);
            MLValue1=MLValue1./NormFactor;
            MLValue0=MLValue0./NormFactor;
            SoftMean=MLValue0-MLValue1;
            %if LLR(j)>=0
            %    dd_bit(1,j)=1;
            %else
            %    dd_bit(1,j)=0;
            %end 
            
            Sym_code(:,BloInd)=SoftMean.';
    end
      
    %Pavg(runs)=mean(D);
    %D=zeros(1,BloInd);
    ncode=reshape(Sym_code,2*len,1);
    b1=randdeintrlv(ncode,4831);
    decoded = vitdec(b1,trel,3,'trunc','unquant'); % Decode. 
    ber(SNRindex)=length(find(decoded-msg))/len; 
end
        


% plot the curve
semilogy(SNRdB, ber);