A Reactive Routing Protocol to Reduce the Number of Channels Switching

In cognitive radio networks, a group of secondary users, in the absence of primary users, attempt to utilize the spectrum without causing interference by employing opportunistic access techniques. However, the sudden reemergence of primary users in the spectrum results in user interference and escalates the frequency of channel switching in a dynamic environment. In such scenarios, analytical methods like Markov processes and game theory are utilized to forecast spectrum mobility. Additionally, given that cognitive radio networks are deployed across various platforms as mobile networks, user mobility can exacerbate the inherent instability of cognitive radio networks, posing challenges in routing. To address these challenges, this study has developed a reactive routing protocol with several advantages: (1) leveraging cognitive radio capabilities and mobility, as well as intersection models, (2) minimizing the frequency of channel switching, (3) preventing user interference, (4) utilizing the availability of channels in the AODV protocol, (5) omitting the use of a common control channel, and (6) establishing a stable path through the calculation of Link Expiration Time (LET). Numerical simulations demonstrate that, in comparison to AODV and CAODV protocols, the proposed protocol has reduced channel switching by approximately 80% with an increase in the number of nodes. Furthermore, in this protocol, control overhead has decreased by over 90% in scenarios involving an escalation in both the number of nodes and their speed.