function [ corr ] = ifo_pss_corr( n, r_pss, x_pss)
x=0;
for i=1:length(x_pss)
x=x+r_pss(1+mod(i+n-1,length(r_pss)))*conj(x_pss(i));
end
corr=real(exp(1i*2*pi*9*n/128)*x);
% corr=abs(x);