Radio environment aware stable routing for multi-hop cognitive radio networks

Routing is a challenging issue when dealing with the multi-hop cognitive radio networks (CRNs). The stability of a route is highly influenced by the behavior of the primary user. The more frequently primary user changes its activity, the less stable spectrum availability the cognitive user has. This causes tremendous route stability fluctuation in CRNs. The radio environmental issues that affect the route stability for the CRNs are: primary exposed node (PEN) and primary hidden node (PHN). These issue makes the route stability becomes one of the most important problem in the CRNs. To address this stability problem, in this paper we propose a radio environment aware stable routing scheme (RASR) for multi-hop CRNs. RASR evaluates the route stability by defining a routing metric, which uses the second smallest eigen value of the Laplacian matrixes. The proposed routing metric takes into account route stability, path length and the activity of the primary users. Moreover, the proposed RASR can avoid the PEN and PHN during routing. To solve the PEN and PHN a channel priority list (CPL) is kept locally by each secondary users. Simulation result shows that the proposed RASR enhances the route stability compared to the conventional routing schemes AODV with hop-count routing metric and connectivity based routing scheme Gymkhana.