mudbp.m

用BP神经网络实现的第三代移动通信CDMA多用户检测算法

function [ecr,epoch,weight1,weight2]=mulrbffcn(snr_in_dB,filterout,truedata,datanum,usernum,help,weight1,weight2)
neuralnum_in=usernum;    % number of neural in layer_in of network
neuralnum_hid=15;   % number of neural in layer_hidden of network
neuralnum_out=1;   % number of neural in layer_out of network
trsamplenum=80;     % number of training samples
trainsample=filterout(:,1:trsamplenum);
trainobject=(truedata(1,1:trsamplenum)+1)/2;
testsample=filterout(:,(trsamplenum+1):datanum);
testobject=(truedata(1,(trsamplenum+1):datanum)+1)/2;
testsamplenum=datanum-trsamplenum;   % number of testing samples
flag=1;
epoch=0;
objecterror=0.01;
lr=0.02;
while(flag==1)
   epoch=epoch+1;
   deltaweight2=zeros(neuralnum_hid,1);
   deltaweight1=zeros(neuralnum_in,neuralnum_hid);
   talerror=0;
   actresulttr=[];
   for i=1:trsamplenum
      hidlayer_in=trainsample(:,i)'*weight1;
      hidlayer_out=sigmoid1(hidlayer_in);
      outlay_in=hidlayer_out*weight2;
      outlay_out=sigmoid2(outlay_in);
      actresulttr=[actresulttr outlay_out];
      error=trainobject(i)-outlay_out;
      errorhelp=(1/2)*(error^2);
      talerror=talerror+errorhelp;
      %differential to weight
      deltaweight2=deltaweight2+error*difsig2(outlay_in)*hidlayer_out';
      hidlayererror=error*difsig2(outlay_in)*weight2;
      hiderrorhelp=hidlayererror.*difsig1(hidlayer_in'); 
    for j=1:neuralnum_hid
      deltaweight1(:,j)=deltaweight1(:,j)+hiderrorhelp(j,1)*trainsample(:,i);     end   
  end
[snr_in_dB epoch talerror help]
%if(talerror>objecterror) 
if(epoch<350)
   %change weight
   weight1=weight1+lr*deltaweight1;
   weight2=weight2+lr*deltaweight2;
 else
   flag=0;
 end
end
%train finished
%======================analyze result=======================
 %to trainsample
trerrorcodenum=0;
for i=1:trsamplenum
   if(actresulttr(i)<0.5)
      actresulttr(i)=0;
   else
      actresulttr(i)=1;
   end
   if(actresulttr(i)~=trainobject(i))
      trerrorcodenum=trerrorcodenum+1;
   end
end
%to testsamples
resulttest=[];
     hidlayer_in=testsample'*weight1;
      hidlayer_out=sigmoid1(hidlayer_in);
      outlay_in=hidlayer_out*weight2;
      outlay_out=sigmoid2(outlay_in);
   resulttest=outlay_out';   
   testerrorcodenum=0;
for i=1:testsamplenum
   if(resulttest(i)<0.5)
      resulttest(i)=0;
   else
      resulttest(i)=1;
   end
   if(resulttest(i)~=testobject(i))
      testerrorcodenum=testerrorcodenum+1;
   end
end
errorcodenum=trerrorcodenum+testerrorcodenum;
ecr=errorcodenum/datanum;