On a Gaussian approximation to the capacity of wireless MIMO systems

We consider the capacity of a single user t → τ MIMO wireless system in a Rayleigh or Ricean fading environment. It is known that a certain central limit theorem exists which states (under certain conditions) that the distribution of the standardized capacity is asymptotically Gaussian as r → ∞, t → ∞ and τ/t → y for some constant y. However we demonstrate the surprising accuracy of a Gaussian approximation to the capacity for virtually all values of τ and t. In order to investigate the accuracy of the Gaussian fit we derive the variance of the capacity in the Rayleigh fading case