Hidden Primary User Awareness in Cognitive Radio Routing: The SBBO Protocol

We propose a distributed routing scheme for cog- nitive radio ad hoc networks which, besides the awareness of the dynamic behavior of the primary users, also considers that some primary users may be hidden to secondary nodes, thus creating asymmetry in the spectrum opportunity availability. We identify this "Hidden Primary User" problem and we introduce in our distributed protocol a mechanism for being aware of it during the routing. To this aim our protocol creates priority lists at the secondary nodes used to have different possibilities to route the data on a path while the primary users activate and deactivate. The tradeoff between packet loss and delay is shown and discussed in the performance analysis.