matlab qpsk

% Program 3-6 % qpsk_fading.m % % Simulation program to realize QPSK transmission system % (under one path fading) % % 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 = 100; % Number of symbols that simulates in each loop ebn0=10; % 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 %******************* 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=160; % 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 %*************************** 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(ifade,qfade,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('BERqpskfad.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 ***************************