How to do Gaussian walk perturbation?

Hello,

In a paper it is said the following:

"The channel is simulated ... with L=10. The channel coefficients are obtained by independently generating each of the taps according to an exponential power delay profile ... . Time variations are then obtained by perturbing the resulting coefficients by means of a zero-mean Gaussian random walk with tunable variance."

How to do the bold part in MATLAB?

I generated the channel coefficients as:

if true
  h=(1/sqrt(2*(L+1))).*(randn(L+1,1)+1i.*randn(L+1,1));
end

Now I need to add time variability by means of zero-mean Gaussian random walk. How?

Thanks

[Saed]

Any help, please?