mimoncmmse.m

是一个四发四收的球型译码程序

function [DetSignal]=MIMONCMMSE(InputMessage,ChM,M,Sigma,NFactor,OrdFlag)
% detect MIMO VBLAST Signals using MMSE Algorithms
% CopyRight(C)    Jim, NCL, UESTC
% Date:           2005-11-17  
% ==========================================================================
% M:        modulation constalletion number
% Fs:       sampling rate per symbol
% ChM:      channel matrix
% Sigma:    the variance of noise
% NFactor:  the normalized factor

% OrdFlag:  the flag of order. 0:SNR,1:SINR,2:LLR
% ==========================================================================

Factor=NFactor;
h=modem.qammod(M);
h2=modem.qamdemod(M);
for j=1:M
    s(j)=modulate(h,j-1)/sqrt(Factor);
end  

% L=length(InputMessage);
Rsg=InputMessage;
[Mrx,Mtx]=size(ChM);

DeSymb=zeros(Mtx,1);
ChanCoeff=zeros(Mtx,1);
% detecting order set
IndSet=1:Mtx;
ChMatrix=ChM;
for n=1:Mtx-1
    Chan=zeros(Mrx,Mtx-n+1);
    %     generate the channel matrix for current processing
    for i=1:Mtx-n+1
        Chan(:,i)=ChMatrix(:,IndSet(i));
    end
    %     ordering the row norm of Moore-Penrose Pseudoinverse of current channel matrix
    
    InvCh=inv(Chan'*Chan+Sigma*Sigma*eye(Mtx-n+1)/(Mtx-n+1))*Chan';  
    
    %    MMSE based on the SINR
    if OrdFlag==1
        MaxNorm=1e-6;
        TempInter=0;
        for m=1:i
            ChanNorm(m)=abs(InvCh(m,:)*Chan(:,m))^2/(norm(InvCh(m,:)*Chan,'fro')^2-abs(InvCh(m,:)*Chan(:,m))^2+Sigma*Sigma/(Mtx-n+1)*norm(InvCh(m,:),'fro')^2);
            if MaxNorm<=ChanNorm(m)
                MaxNorm=ChanNorm(m);
                ind=m;
            end
        end
    else
        MinNorm=1e6;
        ChanNorm=zeros(i,1);
        for m=1:i
            if OrdFlag==0
                ChanNorm(m)=norm(InvCh(m,:),'fro')^2;
            else
                y(m)=InvCh(m,:)*Rsg;
               
                    TempDec=demodulate(h2,sqrt(Factor)*[y(m),0]);
                    TempSignal(m)=sqrt(Factor)*modulate(h,TempDec(1))/Factor;
               
                VarInterference=(Mtx-n+1)*(norm(InvCh(m,:)*Chan,'fro')^2-abs(InvCh(m,:)*Chan(:,m))^2)+Sigma*Sigma*norm(InvCh(m,:),'fro')^2;
                for j=1:M                    
                    Lambda(j)=(abs(y(m)-InvCh(m,:)*Chan(:,m)*s(j))^2-abs(y(m)-InvCh(m,:)*Chan(:,m)*TempSignal(m))^2)/VarInterference;
                    ChanNorm(m)=ChanNorm(m)+exp(-Lambda(j));
                end
            end
            if MinNorm>ChanNorm(m)
                MinNorm=ChanNorm(m);
                ind=m;
            end
        end
    end    

    ChanCoeff=Chan(:,ind);
    DeSymb(IndSet(ind))=InvCh(ind,:)*Rsg;
    
        OrigSymb=demodulate(h2,sqrt(Factor)*[DeSymb(IndSet(ind)),0]);
        DetSignal(IndSet(ind))=OrigSymb(1);
        OrgSymb=sqrt(Factor)*modulate(h,OrigSymb(1))/Factor;

    % cacellating the interference caused by current detected signal
    Rsg=Rsg-ChanCoeff.*OrgSymb;
    % rearrange the detection order set    
    temp=IndSet(ind);
    for k=ind:Mtx-1
        IndSet(k)=IndSet(k+1);
    end
    IndSet(Mtx)=temp;
end
DeSymb(IndSet(1))=ChMatrix(:,IndSet(1))'*Rsg/norm(ChMatrix(:,IndSet(1)),'fro')^2;

    OrigSymb=demodulate(h2,sqrt(Factor)*[DeSymb(IndSet(1)),0]);

DetSignal(IndSet(1))=OrigSymb(1);
% output 
DetSignal=DetSignal.';