I am not sure that I understand when to use Normal Distribution and when to use Poisson distribution! For example, in RF communication the channel noise is mainly modeled as Normal Gaussian distribution, but why? And why not Poisson Distribution? And vice versa, why photon collection on a sensor (shot noise) is modeled as Poisson distribution?
In other words, why receiving data over RF follows a Gaussian noise model, but receiving data over Light follows a Poisson noise model?