www.pudn.com > MIMO-OFDM(simulinkANDmatlab).rar > gmsk_fading.m, change:2001-11-30,size:5109b


% Program 3-19 
% gmsk_fading.m 
% 
% Simulation program to realize GMSK transmission system 
% (under one path fading) 
% 
% Programmed by R.Sawai and H.Harada 
% 
 
%******************** Preparation part ************************************* 
 
sr=256000.0; % Symbol rate 
ml=1;        % ml:Number of modulation levels  
br=sr.*ml;   % Bit rate 
nd = 100;    % Number of symbols that simulates in each loop 
ebn0=15;     % Eb/N0 
IPOINT=8;    % Number of oversamples 
 
%************************* Filter initialization *************************** 
 
irfn=21;                  % Number of taps 
B=0.25*sr; 
B2=0.6*sr; 
[xh] = gaussf(B,irfn,IPOINT,sr,1);   %Transmitter filter coefficients  
[xh2] =gaussf(B2,irfn,IPOINT,sr,0);  %Receiver filter coefficients  
 
%******************* Fading initialization ******************** 
% If you use fading function "sefade", you can initialize all of parameters. 
% Otherwise you can comment out the following initialization. 
% The detailed explanation of all of valiables are mentioned in Program 2-8. 
 
% Time resolution 
 
tstp=1/sr/IPOINT;  
 
% Arrival time for each multipath normalized by tstp 
% If you would like to simulate under one path fading model, you have only to set  
% direct wave. 
 
itau = [0]; 
 
% Mean power for each multipath normalized by direct wave. 
% If you would like to simulate under one path fading model, you have only to set  
% direct wave. 
dlvl = [0]; 
 
% Number of waves to generate fading for each multipath. 
% In normal case, more than six waves are needed to generate Rayleigh fading 
n0=[6]; 
 
% Initial Phase of delayed wave 
% In this simulation four-path Rayleigh fading are considered. 
th1=[0.0]; 
 
% Number of fading counter to skip  
itnd0=nd*IPOINT*100; 
 
% Initial value of fading counter 
% In this simulation one-path Rayleigh fading are considered. 
% Therefore one fading counter are needed. 
   
itnd1=[1000]; 
 
% Number of directwave + Number of delayed wave 
% In this simulation one-path Rayleigh fading are considered 
now1=1;         
 
% Maximum Doppler frequency [Hz] 
% You can insert your favorite value 
fd=320;        
 
% You can decide two mode to simulate fading by changing the variable flat 
% flat     : flat fading or not  
% (1->flat (only amplitude is fluctuated),0->nomal(phase and amplitude are fluctutated) 
flat =1; 
 
%******************** START CALCULATION ************************************* 
 
nloop=1000;  % 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 
 
%*************************** GMSK Modulation ********************************   
 
    data11=2*data1-1; 
    data2=oversamp(data11,length(data11),IPOINT);     
    data3=conv(data2,xh);                           % NEW for GMSK 
 
    th=zeros(1,length(data3)+1); 
    ich2=zeros(1,length(data3)+1); 
    qch2=zeros(1,length(data3)+1); 
 
    for ii=2:length(data3)+1 
	    th(1,ii)=th(1,ii-1)+pi/2*data3(1,ii-1)./IPOINT; 
    end 
 
    ich2=cos(th); 
    qch2=sin(th); 
 
%************************** 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(ifade,qfade,attn);% add white gaussian noise 
	   
    [ich4,qch4] = compconv(ich3,qch3,xh2); 
    
    syncpoint =irfn*IPOINT-IPOINT/2+1; 
    ich5=ich4(syncpoint:IPOINT:length(ich4)); 
    qch5=qch4(syncpoint:IPOINT:length(qch4)); 
         
%**************************** GMSK Demodulation ***************************** 
 
    demoddata2(1,1)=-1; 
 
    for k=3:2:nd*ml+1 
         demoddata2(1,k)=ich5(1,k)*qch5(1,k-1)*cos(pi*(k))>0; 
    end 
 
    for n=2:2:nd*ml+1 
         demoddata2(1,n)=ich5(1,n-1)*qch5(1,n)*cos(pi*(n))>0; 
    end 
 
    [demodata]=demoddata2(1,2:nd*ml+1); 
     
%************************** 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('BERgmskfad.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 ***************************