% Program 3-1
% bpsk.m
%
% Simulation program to realize BPSK transmission system
%
% Programmed by H.Harada and T.Yamamura,
%
echo off;
clear all;
%******************** Preparation part **********************

sr=256000.0; % Symbol rate
ml=1;        % Number of modulation levels
br=sr.*ml;   % Bit rate (=symbol rate in this case)
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 filter 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
  
nebn0=7;     % number of ber-ebn0 points
ber=0:nebn0;

for ebn0=1:nebn0,
noe = 0;    % Number of error data
nod = 0;    % Number of transmitted data
iii=0;

while noe<=2000,    
%******************** START CALCULATION *********************
% for iii=1:nloop
% nloop=100;  % Number of simulation loops
iii=iii+1;
%******************** Data generation ********************************  

	data=rand(1,nd)>0.5;  % rand: built in function

%******************** BPSK Modulation ***********************  

    data1=data.*2-1;
	[data2] = oversamp( data1, nd , IPOINT) ;
	data3 = conv(data2,xh);  % conv: built in function

%****************** Attenuation Calculation *****************
	
    spow=sum(data3.*data3)/nd;
	attn=0.5*spow*sr/br*10.^(-ebn0/10);
	attn=sqrt(attn);
   
%********************** Fading channel **********************

  % Generated data are fed into a fading simulator
  % In the case of BPSK, only Ich data are fed into fading counter
  % [ifade,qfade]=sefade(data3,zeros(1,length(data3)),itau,dlvl,th1,n0,itnd1,now1,length(data3),tstp,fd,flat);
  
  % Updata fading counter
  %itnd1 = itnd1+ itnd0;

%************ Add White Gaussian Noise (AWGN) ***************
	
    inoise=randn(1,length(data3)).*attn;  % randn: built in function
	data4=data3+inoise;
	data5=conv(data4,xh2);  % conv: built in function

	sampl=irfn*IPOINT+1;
	data6 = data5(sampl:8:8*nd+sampl-1);
    
%******************** BPSK Demodulation *********************

    demodata=data6 > 0;

%******************** Bit Error Rate (BER) ******************

    noe2=sum(abs(data-demodata));  % sum: built in function
	nod2=length(data);  % length: built in function
	noe=noe+noe2;
	nod=nod+nod2;

	% fprintf('%d\t%e\n',iii,noe2/nod2);
    % end % for iii=1:nloop     
end % for noe<=100 
%********************** Output result ***************************
ber(ebn0) = noe/nod; 
fprintf('%d\t%e\n',ebn0, ber(ebn0));
% fprintf('%d\t%d\t%d\t%e\n',ebn0,noe,nod,noe/nod);
% fid = fopen('BERbpsk.dat','a');
% fprintf(fid,'%d\t%e\t%f\t%f\t\n',ebn0,noe/nod,noe,nod);
% fclose(fid);

end % for ebn0

SNRindB1=0:nebn0;
SNRindB2=0:0.1:nebn0;
echo on;
for i=1:length(SNRindB2),
    SNR=exp(SNRindB2(i)*log(10)/10);            % signal to noise ratio
    theo_err_prb(i)=0.5*erfc(sqrt(SNR));        % theoretical bit error rate
    echo off; 
end;
echo on;
% Plotting commands follow
semilogy(SNRindB1,ber,'*');
hold
semilogy(SNRindB2,theo_err_prb);

%******************** end of file ***************************