www.pudn.com > 43680498viterbidecode.rar > BPSK_myself_VI.m

% function Y_Y=BPSK_myself_VI() 
%用自己编的卷积码编解函数cnv_encd、viterbi仿真OFDM  
clear; 
 
 
% tic 
N=64; %The number of carriers 
 
% h=gausComplex(1,3); 
h=[1]; 
%h=[0.407,0.815,0.407]; 
 
 
L=length(h); 
v=length(h)-1;%the size of the cyclic prefix 
 
 
b=1;%For QPSK, one symbol carries  source bits 
 
 
 
CBPSK=[-1,1]; 
BBPSK=[0;1]; 
 
    
srcBlockSize=N*b; 
q=2^b;%the size of the signal set 
 
 
Es=real(sum(CBPSK.*conj(CBPSK))/q);%ES= sum((abs(C16QAM)).^2)/qq; 
 
 
Es=Es/N;% If noise is generated in time domain, Es should be multiplied by a factor 1/N 
 
 
 
Eb=Es/b; 
 
Na=N+v;%The size of the transmitted block with cyclic prefix 
 
Nb=N+v+L-1;%The size of the liner convolutional result of the transmitted block and the channel 
 
noiseVec=zeros(1,Nb); 
X=zeros(1,N); % one source symbol block 
x=zeros(1,N); % for the IFFT of X 
xt=zeros(1,Na); % transmitted time domain block with cyclic prefix 
yt=zeros(1,Nb);%received time domain block 
 
y=zeros(1,N);%received time domain signal removal of CP 
Y=zeros(1,N);%the vector fot FFT of y 
 
XD=zeros(1,N); 
dist=zeros(1,q); 
src=zeros(1,srcBlockSize); 
rev=zeros(1,srcBlockSize); 
index=0; 
 
H=fft(h,N); %the frequency domain character of the channel 
 
 
randn('state',sum(100*clock)); 
 
 
recIndex=1;%an index for recoder buffer 
 
for EbN0=0:1:0 
    fprintf('%d>',EbN0) 
 
    N0=Eb*10^(-EbN0/10); 
    noiseRoot=sqrt(N0/2); 
         
    errorCount=0; 
    testLength=0; 
    BER=0; 
    while(1) 
        testLength=testLength+srcBlockSize; 
        input=(randn(1,srcBlockSize)>0);% Generate a source block (equal probability) 
  
 %对原信息编码  
k00=1; 
G=[1 1 1;1 0 1]; 
src=cnv_encd(G,k00,input); 
[row_src col_src]=size(src) ;     
               
        %The following part complement the conversion of binary to q-QAM symbol 
        %a faster method is to use an index table,here we convert binary to symbol by calculating 
        for k=1:1:N 
            startIndex=(k-1)*b+1; 
            endIndex=startIndex+b-1; 
            vec=src(startIndex:endIndex); 
            for t=1:1:q 
                temp=sum(abs(vec-BBPSK(t,:))); 
                if(temp<1e-5) 
                    index=t; 
                    break; 
                end 
            end 
            X(k)=CBPSK(index); 
        end 
         
        %Mapping for frequency domain to time domain (multi-carrier modulation) 
        x=ifft(X); %IFFT 
         
        %Add CP 
        xt(1:v)=x( (N-v+1):N); 
        xt((v+1):(N+v))=x(1:N); 
         
        %Passing the channel with noise 
        yt=conv(xt,h); 
        noiseVec=randn(1,Nb)+j*randn(1,Nb);%Generate noise 
        noiseVec=noiseVec*noiseRoot; 
        yt=yt+noiseVec; 
         
        %Remove the cyclic prefix 
        y=yt((v+1):(v+N));         
         
        %FFT of y 
        Y=fft(y); 
         
        %Equalizer on the frequency domain 
        XD=Y./H; 
 
        for k=1:1:N 
            %minminum distance decision 
            dist=abs(XD(k)-CBPSK); 
             [temp,index]=min(dist); 
             vec=BBPSK(index,:); 
             startIndex=(k-1)*b+1; 
             endIndex=startIndex+b-1; 
             rev(startIndex:endIndex)=vec; 
              
        end 
         
        [row_rev col_rev]=size(rev); 
        decode=viterbi(G,k00,rev); 
        [row_input col_input]=size(input); 
        [row_decode col_decode]=size(decode); 
         
         
        errorNum=sum(xor(input,rev)); 
                 
        errorCount=errorCount+errorNum; 
        BER=errorCount/testLength; 
         
         
                 
         
        % plot(real(XD),imag(XD),'*'); %This can be used to watch the received signal set 
         
        if(BER>0) 
            if(EbN0<=9) 
                temp=200/BER; 
            else 
                temp=100/BER; 
            end 
                        
            if(testLength>temp)  
                if(testLength>150000) 
                    break;     
                end 
            end 
             
        end 
        if(testLength>900000000) 
%         if(testLength>90000000) 
            break;     
        end 
         
    end 
    BER_Rec(recIndex)=BER; 
    EbN0_Rec(recIndex)=EbN0; 
    testLength_Rec(recIndex)=testLength; 
    recIndex=recIndex+1; 
end 
 
%Save the result 
% save BPSK_myself_myself_db0to8 BER_Rec; 
BER_Rec 
%Watch the results 
semilogy(EbN0_Rec,BER_Rec,'k-s'); 
 
% time_in_hour=toc/3600 
% save data\BPSK_myself_time time_in_hour