Quantifying the Primary´s Guard Zone under Cognitive User´s Routing and Medium Access

In this article, we derive a closed form expression for the radius of a guard zone (r_e) required at a primary receiver operating in the presence of a cognitive radio network while ensuring the primary´s desired quality of service (QoS). We demonstrate that r_e is not only strongly coupled with the primary´s QoS requirement but it is also dependent upon the secondary network´s connectivity, medium access, QoS and routing mechanisms.