16qam调制matlab

% qam16_fading

%

% Simulation program to realize 16QAM transmission system

% (under one path fading)

%

% Programmed by H.Harada and R.Funada

%

%******************** preparation part *************************************

sr=256000.0; % Symbol rate

ml=4; % 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=15; % 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

*** Attenuation Calculation ***********************

spow=sum(ich2.*ich2+qch2.*qch2)/nd;

attn=0.5*spow*sr/br*10.^(-ebn0/10);

attn=sqrt(attn);

%********************** Fading channel **********************

% Generated data are fed into a fading simulator

[ifade,qfade,ramp]=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

%*************** Compensate the fluctuation of fading by ramp*******************

ich3=ich3./ramp(1:length(ramp));

qch3=qch3./ramp(1:length(ramp));

[ich4,qch4]= compconv(ich3,qch3,xh2);

sampl=irfn*IPOINT+1;

ich5 = ich4(sampl:IPOINT:length(ich4));

qch5 = qch4(sampl:IPOINT:length(ich4));

%**************************** 16QAM Demodulation *****************************

[demodata]=qamdemod(ich5,qch5,1,nd,ml);

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

noe2=sum(abs(data1-demodata));

nod2=length(data1);

noe=noe+noe2;

nod=nod+nod2;

fprintf('%d\%e\

',iii,noe2/nod2);

end % for iii=1:nloop

%********************** Output result ***************************

ber = noe/nod;

fprintf('%d\%d\%d\%e\

',ebn0,noe,nod,noe/nod);

fid = fopen('BERqamfad.dat','a');

fprintf(fid,'%d\%e\%f\%f\\

',ebn0,noe/nod,noe,nod);

fclose(fid);

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