CFO_Classen.m

function CFO_est=CFO_Classen(yp,Nfft,Ng,Nps)
% Frequency-domain CFO estimation using Classen method based on pilot tones

%MIMO-OFDM Wireless Communications with MATLAB¢ç   Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang
%2010 John Wiley & Sons (Asia) Pte Ltd

if length(Nps)==1, Xp=add_pilot(zeros(1,Nfft),Nfft,Nps); % Pilot signal
 else Xp=Nps; % If Nps is given as an array, it must be a pilot sequence Xp
end
Nofdm=Nfft+Ng; kk=find(Xp~=0); Xp=Xp(kk); % Extract pilot tones
for i=1:2 
   yp_without_CP = remove_CP(yp(1+Nofdm*(i-1):Nofdm*i),Ng);
   Yp(i,:) = fft(yp_without_CP,Nfft);
end
%temp= Y(1,kk)*Xp(kk)';
CFO_est = angle(Yp(2,kk).*Xp*(Yp(1,kk).*Xp)')/(2*pi)*Nfft/Nofdm; % Eq.(5.31)
%fprintf(' dFCFO-Esti_FFO=%8.5f-%8.5f\n', dFCFO,Esti_FFO);
% MSE = MSE + (CFO_est-FCFO)*(CFO_est-CFO);