www.pudn.com > 05041062qpsk-fading.zip > lving.m

 
%******************** Preparation part ************************************* 
clear all; 
echo off; 
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 = 100;    % Number of symbols that simulates in each loop 
T=nd/sr; 
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  
 
%******************* Fading initialization ******************** 
tstp=1/sr/IPOINT;                    % Time resolution 
itau = [0];                          % Arrival time for each multipath normalized by tstp % direct wave. 
dlvl = [0];                          % Mean power for each multipath normalized by direct wave.% direct wave. 
n0=[6];                              % Number of waves to generate fading for each multipath. 
th1=[0.0];                           % Initial Phase of delayed wave 
itnd0=nd*IPOINT*100;                 % Number of fading counter to skip  
itnd1=[1000];                        % Initial value of fading counter 
now1=1;                              % Number of directwave + Number of delayed wave 
fd=160;                              % Maximum Doppler frequency [Hz] 
flat =1;                             % flat     : flat fading or not 
 
%******************** START CALCULATION ************************************* 
ebn0=0:1:10;% Eb/N0 
for tt=1:length(ebn0) 
nloop=500;  % 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);  
   
    ich20 = ich2(irfn*IPOINT/2+1:nd*IPOINT+irfn*IPOINT/2); 
    ICH2 = fftshift(fft(ich20)); 
    P2 = ICH2.*conj(ICH2)/T;              %功率计算  
%**************************** 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(tt));    % 当需要计算衰落时，ich2,qch2改为ifade,qfade 
	[ich4,qch4]= compconv(ich3,qch3,xh2); 
 
    syncpoint=irfn*IPOINT+1; 
    ich5=ich4(syncpoint:IPOINT:length(ich4)); 
    qch5=qch4(syncpoint:IPOINT:length(qch4)); 
   
   ich40 = ich4(irfn*IPOINT/2+1:nd*IPOINT+irfn*IPOINT/2); 
   ICH4 = fftshift(fft(ich40)); 
   P4 = ICH4.*conj(ICH4)/T;                   %功率计算 
     
%**************************** 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; 
end                                           % for iii=1:nloop     
 
%********************** Output result *************************** 
 
ber(tt) = noe/nod; 
 
fprintf('%e\n',noe/nod);                      % fprintf: built in function 
 
end 
%******************** 计算理论值 *************************** 
%     SNRindB2=0:0.1:30; 
% for i=1:length(SNRindB2), 
%      snr1=exp(SNRindB2(i)*log(10)/10); 
%      snr2=sqrt(1+1/snr1); 
%      snr3=1-1/snr2;            
%      theo(i)=0.5*snr3;       
% end; 
semilogy(ebn0,ber,'g*');            
% hold on; 
% semilogy(SNRindB2,theo); 
hold on; 
SNRindB3=0:0.2:10; 
for i=1:length(SNRindB3), 
    SNR=exp(SNRindB3(i)*log(10)/10);      % signal to noise ratio 
    snr=sqrt(SNR) 
    theo_err_prb(i)=0.5*erfc(snr);        % theoretical bit error rat 
end; 
semilogy(SNRindB3,theo_err_prb); 
 
% Hs=spectrum.welch; 
% figure(2) 
% subplot(2,1,1)           %基带波形 
% stem(data1); 
% subplot(2,1,2) 
% psd(Hs,data1,'Fs',tstp); %基带功率谱 
%  
% figure(3) 
% subplot(2,1,1)          %调制波形 
% plot(ich2); 
% subplot(2,1,2) 
% psd(Hs,ich2,'Fs',tstp); %调制后功率谱 
%  
%  
% figure(4) 
% subplot(2,1,1) 
% plot(ich4); 
% subplot(2,1,2) 
% psd(Hs,ich4,'Fs',tstp); %加噪后功率谱 
%  
% scatterplot([(ich)',(qch)']);          
%  
% scatterplot([(ich5)',(qch5)']);  %星座图