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.