www.pudn.com > MODULATION.RAR > qpsk.m, change:2001-11-30,size:3055b


% Program 3-5 
% qpsk.m 
% 
% Simulation program to realize QPSK transmission system 
% 
% Programmed by H.Harada and T.Yamamura 
% 
 
%******************** Preparation part ************************************* 
 
sr=256000.0; % Symbol rate 
ml=2;        % ml:Number of modulation levels (BPSK:ml=1, QPSK:ml=2, 16QAM:ml=4) 
br=sr .* ml; % Bit rate 
nd = 1000;   % Number of symbols that simulates in each loop 
ebn0=3;      % Eb/N0 
IPOINT=8;    % Number of oversamples 
 
%************************* Filter initialization *************************** 
 
irfn=21;                  % Number of taps 
alfs=0.5;                 % Rolloff factor 
[xh] = hrollfcoef(irfn,IPOINT,sr,alfs,1);   %Transmitter filter coefficients  
[xh2] = hrollfcoef(irfn,IPOINT,sr,alfs,0);  %Receiver filter coefficients  
 
%******************** START CALCULATION ************************************* 
 
nloop=100;  % Number of simulation loops 
 
noe = 0;    % Number of error data 
nod = 0;    % Number of transmitted data 
 
for iii=1:nloop 
     
%*************************** Data generation ********************************   
	 
    data1=rand(1,nd*ml)>0.5;  % rand: built in function 
     
%*************************** QPSK Modulation ********************************   
 
    [ich,qch]=qpskmod(data1,1,nd,ml); 
	[ich1,qch1]= compoversamp(ich,qch,length(ich),IPOINT);  
	[ich2,qch2]= compconv(ich1,qch1,xh);  
      
%**************************** Attenuation Calculation *********************** 
	 
    spow=sum(ich2.*ich2+qch2.*qch2)/nd;  % sum: built in function 
	attn=0.5*spow*sr/br*10.^(-ebn0/10); 
	attn=sqrt(attn);  % sqrt: built in function 
      
%********************** Fading channel ********************** 
 
  % Generated data are fed into a fading simulator 
  % [ifade,qfade]=sefade(ich2,qch2,itau,dlvl,th1,n0,itnd1,now1,length(ich2),tstp,fd,flat); 
   
  % Updata fading counter 
  %itnd1 = itnd1+ itnd0; 
 
%********************* Add White Gaussian Noise (AWGN) ********************** 
	 
    [ich3,qch3]= comb(ich2,qch2,attn);% add white gaussian noise 
	[ich4,qch4]= compconv(ich3,qch3,xh2); 
 
    syncpoint=irfn*IPOINT+1; 
    ich5=ich4(syncpoint:IPOINT:length(ich4)); 
    qch5=qch4(syncpoint:IPOINT:length(qch4)); 
         
%**************************** QPSK Demodulation ***************************** 
 
    [demodata]=qpskdemod(ich5,qch5,1,nd,ml); 
 
%************************** Bit Error Rate (BER) **************************** 
 
    noe2=sum(abs(data1-demodata));  % sum: built in function 
	nod2=length(data1);  % length: built in function 
	noe=noe+noe2; 
	nod=nod+nod2; 
 
	fprintf('%d\t%e\n',iii,noe2/nod2);  % fprintf: built in function 
 
end % for iii=1:nloop     
 
%********************** Output result *************************** 
 
ber = noe/nod; 
fprintf('%d\t%d\t%d\t%e\n',ebn0,noe,nod,noe/nod);  % fprintf: built in function 
fid = fopen('BERqpsk.dat','a'); 
fprintf(fid,'%d\t%e\t%f\t%f\t\n',ebn0,noe/nod,noe,nod);  % fprintf: built in function 
fclose(fid); 
 
%******************** end of file ***************************