ic_mmse.m

mimo-mc-cdma系统上行链路中分别针对单用户和多用户的不同检测算法的比较

clear all
Nc=64;                          % the total carriers
K=1;                            % the number of users 
M=4;                            % the number of transmit antennas
N=4;                            % the number of receive antennas 
G=16;                            % the processing gain
S=Nc/G;                         % the number of signals of each group
Tc=1/1.2288e6;                  % chip duration 
Ts=Tc;                          % symbol duration
circle_times=2000;
SNR_dB=0:4:28;
%KK=4:2:16;
SGMA=1;
e=zeros(1,21);

%SNR_dB=20;
%SNR=10^(SNR_dB/10);
%Pow=2*SGMA^2*SNR;
%for x=1:length(KK)
%    K=4+2*(x-1);
    
H=zeros(N,M,Nc,K);
for k=1:K
  for p=1:Nc
    for m=1:M
      for n=1:N
        H(n,m,p,k)=raylrnd(0.5)*exp(j*2*pi*rand);  
      end
    end
  end
end

for x=1:length(SNR_dB)
  SNR(x)=10^(SNR_dB(x)/10);
  Pow(x)=2*SGMA^2*SNR(x)/M;
  
  for t=1:circle_times
    TransmitSignal=rand(M,S,K);
    TransmitSignal=(TransmitSignal>=0.5)-(TransmitSignal<0.5);

    % spreading
    SpreadCode=hadamard(G);
    TS=[];
    for k=1:K
      SD=[];
      for s=1:S
        TS=TransmitSignal(:,[s*ones(1,G)],:);
        for g=1:G
          SpreadData(:,g,k)=TS(:,g,k)*SpreadCode(k,g);
        end
        SD=[SD SpreadData(:,:,k)];
      end
      SP(:,:,k)=SD;
    end

  % multicarrier modulation
    for p=1:Nc
      for k=1:K
         TX(:,p,k)=H(:,:,p,k)*SP(:,p,k);
      end
    end
    TX=sqrt(Pow(x))*ifft(TX,[],2);
    %TX=sqrt(Pow)*ifft(TX,[],2);

  % transmit
    AWGN=SGMA*randn(N,Nc);
    TX=sum(TX,3);
    for p=1:Nc
       RX(:,p)=TX(:,p)+AWGN(:,p);
    end

  % demodulation
    DM=fft(RX,[],2);

  % multiuser detection and V-blast detection
    h=H;
    for p=1:Nc
       g=mod(p,G);
       if (g==0)
         g=G;
       end
       for k=1:K
          Gg(:,:,p,k)=pinv(h(:,:,p,k));
          %Gg(:,:,p,k)=inv(h(:,:,p,k)'*h(:,:,p,k)+eye(M))*h(:,:,p,k)';
          DecisionVector(:,p,k)=DM(:,p)*SpreadCode(k,g);
          for m=1:M
            for a=1:M
              Power(a,p,k)=Gg(a,:,p,k)*Gg(a,:,p,k)';
            end
            [A,J]=min(Power(:,p,k));
            AntennaOrder(m,p,k)=J;
            W(J,p,k)=Gg(J,:,p,k)* DecisionVector(:,p,k);
            Output(J,p,k)=(real(W(J,p,k))>=0)-(real(W(J,p,k))<0); 
            DecisionVector(:,p,k)=DecisionVector(:,p,k)-sqrt(Pow(x))*h(:,J,p,k)*Output(J,p,k);
            h(:,J,p,k)=0;
            Gg(:,:,p,k)=pinv(h(:,:,p,k)); 
            %Gg(:,:,p,k)=inv(h(:,:,p,k)'*h(:,:,p,k)+eye(M))*h(:,:,p,k)';
            for b=1:m
              Gg(AntennaOrder(b,p,k),:,p,k)=10;
            end  
          end 
          % reset
          for m=1:M
            ResetAntenna(AntennaOrder(m,p,k),p,k)=W(m,p,k);
          end
       end
    end

  % subcarrier combination
    C=[];
    FinalData=[];
    for s=1:S
       C(:,:,:)=W(:,(s-1)*G+1:s*G,:);
       FinalData(:,s,:)=sum(C,2);
    end
    FinalData=(FinalData>=0)-(FinalData<0);

  % compute the BER
    e(x)=e(x)+0.5*sum(sum(sum(abs(TransmitSignal-FinalData))));
  end
  per(x)=e(x)/(S*M*K*circle_times);
end
hold on
semilogy(SNR_dB,per(:),'.')
%semilogy(KK,per(:),'x')
xlabel('Eb/No(dB)');
%xlabel('K');
ylabel('BER');