% This function generates pulse response of channel
% Jakes model
% ll represent the number of path
% t is time. 
% fd=115 
function f=channelcorr(fd,t,ll)
s=35;
rand('state',ll);

h1=0;
h2=0;
for k=1:s-1
    sita(k)=2*pi*rand;
    h1=h1+sqrt(2)/sqrt(s-1/2)*cos(pi*k/(s-1))*cos(2*pi*fd*cos(pi*k/(2*s-1))*t+sita(k));
    h2=h2+sqrt(2)/sqrt(s-1/2)*sin(pi*k/(s-1))*cos(2*pi*fd*cos(pi*k/(2*s-1))*t+sita(k));
end
sita(s)=rand;
h1=h1+1/(sqrt(2)*sqrt(s-1/2))*cos(2*pi*fd*t+sita(s));
h2=h2+1/(sqrt(2)*sqrt(s-1/2))*cos(2*pi*fd*t+sita(s));
f(1,1)=h1+j*h2;