p16.m

OFDM digital modulation for wireless communications systems. multilevel quadrature modulation with c

% ===================================================================
% Aim   : Simulation of 16-QAM-OFDM Orthogonal-PD+TWTA  for AWGN channel
% Date  : 21/05/2007
% Name  : Nibaldo Rodriguez
% Update: 21/05/2007
% ===================================================================
close all
clear

load pesos
Nc=256;  % subcarrier Numbers
M=16;    % Constellation size
Nblock=ceil(1e4/(log2(M)*Nc))% block Numberr
L=log2(M)*Nc*Nblock; % Transmission Bits
Constellation =constela(log2(M));
Constellation=reshape(Constellation,M,1);
CC=Constellation; 

fprintf('Waiting ...Mr...\n');
SNRinic=15;
SNRend=15;
SNRInc=0.5;
Iterations=40; 
kk=0;
ibo=power(10,0/10);
randn('seed',sum(100*clock));
for snr=SNRinic:SNRInc:SNRend
    EbNo=power(10,-snr/10); % average SNR per bits
    ber=zeros(1,Iterations);% BER partial by itertions
    for iter=1:Iterations
        x=round(rand(1,L)); % gennerated bits
        q=modula(x,M,Constellation); % QAM 
        
        S_P=reshape(q,Nc,Nblock); % Serial to Parallel
        SymOfdm=sqrt(Nc)*ifft(S_P,Nc); % Multicarrier Modulation
        SymTx=reshape(SymOfdm,1,Nc*Nblock); % Parallel to Serial
        %=================================
        % Amplification TWTA
        SymTx=ibo*SymTx;
        ps=angle(SymTx);
        r=abs(SymTx);
%         r(find(r==0))=eps;
         wo=max(abs(r));
         My= pd_orto((r./wo),H,v,w);
         Ny=My.^2./(1+My.^2);
         Ny=Ny.*(pi/3);
         y=My.*exp(-j.*Ny).*exp(j.*ps');
        % y=(SymTx./r).*y';
        z=twtaa(y,wo);
        % ====  AWGN Chhanel=====
        Eb1=sum(real(z).^2)./L;
        Eb2=sum(imag(z).^2)./L;
        Eb=Eb1+Eb2;
        N_o=Eb*EbNo;
        sigma=sqrt(N_o/2);
        nr=sigma.*randn(1,length(z));
        ni=sigma.*randn(1,length(z));
        noise=nr+sqrt(-1).*ni;

        %====Receiver ============
        rx=z+noise';
        rx_sp=reshape(rx,Nc,Nblock); % Serial to Parallel
        rx_q=(1/sqrt(Nc))*fft(rx_sp,Nc); % Multicarrier Demodulation OFDM
        rx_ps=reshape(rx_q,1,Nc*Nblock); % Parallel to Serial
                   
        %=========== QAM Demodulation
        Len=length(rx_ps);
        for i=1:Len
            [a,index(i)]=min(abs(rx_ps(i)-Constellation(:)));
        end
        bit2=de2bi(index-1,log2(M));
        xx=reshape(bit2',1,length(x));
        err=sum(ne(x,xx));
        ber(iter)=err/L;  % Ber partial
        fprintf('\n Iter %d BER %f',iter,ber(iter))
    end
    kk=kk+1;
    AvgBer(kk)=sum(ber(:))/Iterations;
    fprintf('\n SNR db %2.2f Avg BER %f',snr,AvgBer(kk))
    save bof16  AvgBer
   
end
% 
% 
% t=SNRinic:SNRInc:SNRend;
% a=6:0.25:14; %13.75 %19;
% b=bteo(a,M);
% figure(1)
% semilogy(t,AvgBer,'-*r',a,b,'-+k')
% xlabel('SNR dB')
% ylabel('B E R ')
% grid on

% figure(2)
% plot(dd,'+')
% grid on
% 
m1=sum(norm(q-rx_ps).^2);
m2=sum(norm(q).^2);
EE=100*(1-sqrt(m1/m2))