function [xP] = model_AR(xP,DS,delay);
%This routine uses the classical AR correlation method to model the channel
global nTx nRx Npart 

%Using correlation method
B = bessel(0,2*pi*DS);
Nv = 2*(1 - B*B);

for d = 1:delay;  %Trying to predict to end of block
    xP = B*xP + sqrt(Nv/2)*(randn(nRx,nTx,Npart) + i*randn(nRx,nTx,Npart));
end