N=5; %data points
h = [-0.1340 - 1.0315i,  -0.2770 - 1.0810i,   0.7774 - 0.5708i]; %complex valued channel coefficients
N=5;
temp =0.0;
z = [0.2 + 1j*0.2, 0.21 - 1j*0.5, 1.2 + 1j*0.3, 1.5 + 1j*0.5, -1.5 - 1j*0.5];



     yhat = filter(h,1,z);
       for ii = 1: N
         A = y(ii)*conj(y(ii));
       B = y(ii)*yhat(ii);
       C = (A-B)*conj(A-B);
       temp = temp + C;

    end

       noise_var = temp/N %sigma2w