On Approximating the Cognitive Radio Aggregate Interference} \IEEEaftertitletextvspace{-1\baselineskip

The aggregate interference caused on a primary receiver by Cognitive Radio (CR) nodes distrbuted uniformly in an annular region around it is investigated, assuming Rayleigh fading and path loss. By approximating the aggregate interference with that caused by the nearest CR interferer, the exact analytical moment generating function for the nearest interferer is derived for cases of no power control and distance based power control. The outage probability based on the approximation is derived, which is a tight lower bound under certain conditions.