The Primary Exclusive Region in Cognitive Networks

In this paper, we consider a cognitive network in which a single primary transmitter communicates with primary receivers within an area of radius R_O, called the primary exclusive region (PER). Inside this region, no cognitive users may transmit. Outside the PER, provided that the cognitive transmitters are at a minimal distance isin_p from a primary receiver, they may transmit concurrently with the primary user. We determine bounds on the primary exclusive radius R_O and the guard band isin_p to guarantee an outage performance for the primary user. Specifically, for a desired rate C_O and an outage probability beta, the probability that the primary user´s rate falls below C_O is less than beta. This performance guarantee holds even with an arbitrarily large number of cognitive users uniformly distributed with constant density outside the primary exclusive region.