Impact of shadowing on the primary exclusive region in cognitive networks

In this paper we use the spatial dimension of spectrum sharing to allow the re-use of a radio frequency spectrum, first licensed to a primary user, by several secondary or cognitive users, while providing an outage performance to the primary user. In particular, we consider a primary receiver in the center of an exclusive region (or no-talk zone) and a guard band, within which there is no secondary transmitter, in order to protect the primary transmission against strong interference. Outside the exclusive region and the guard band, N cognitive transmitters are distributed randomly. Moreover, the primary service is protected by an outage constraint making the primary rate to be greater, most of the time, than a minimal necessary rate C₀. We study the effects of shadowing and path-loss exponent on the primary exclusive region.