Aggregate Interference Analysis for Interweave Cognitive Networks

This paper investigates the aggregate interference from interweave cognitive secondary nodes spatially distributed in a finite Poisson field. These secondary nodes sense an out-of-band beacon to initiate their transmissions, which can be concurrent with those of the primary system if a sensing error is made. The resulting aggregate interference is analyzed in this paper. For this purpose, general Nakagami-m fading and path-loss are assumed for all relevant channels. Moreover, we incorporate random secondary node transmit powers with any probability distribution. The analysis includes the exact moment generating function (MGF) of the aggregate interference along with the exact outage probability of the primary system. Furthermore, we develop a simple MGF approximation which is valid for severely fading channels and for lower beacon reception threshold to beacon transmit power ratios. Finally, we show that a lower fading severity significantly improves the diversity order of the PR due to more accurate spectrum sensing by the secondary nodes.