Research And Simulation On The Routing Protocol Of The Cognitive Radio Network

Along with the rapidly increasing requirement of wireless communications, the frequency resources become more and more precious. On the other hand, the current frequency utilization ratio is regrettably low: some hot bands are excessively overloaded while most bands are not fully used. In order to resolve the radio frequency rarity problem and enhance frequency utilization, the CR(Cognitive Radio) technology is brought forward. The CRN (Cognitive Radio Network) is the main topic of the Cognitive Radio research and its working principle can be summarized as cognitive nodes actively sense radio spectrums, opportunistically select and access the best fitted spectrum, schedule data communication in the form of Ad Hoc.Based on the comprehensive analysis of CR evolution, CRN architecture and the current research on its routing, this paper discusses several CRN characteristics and key routing problems lead by those characteristics, including multi-band communication differences, control band selection problem, influence of dynamic available bands and features of non-identical and partly consistent available band sensed by nodes, and points out that a good route in CRN should have three features: low conflicts and interferences, low spectrum switches, and low hops.The author presents a new routing metric Expected Path Delay, EPD for CRN, designs and implements a CRN routing protocol in simulation platform. The protocol uses spectrum monitor & manager to monitor and manage every bands sensed and initializes foothold band in collaboration with neighbors. It also uses probe packets in the media access control layer to compute real-time reception ratio of a band. In route selection, the protocol calculates every candidate route's EPD and picks up the one that has the smallest EPD. The simulation shows that the proposed protocol can greatly decrease the potential transmission conflicts and interferences in the stage of network deployment and can select low path delay, high throughput and steady delivery ratio routes through joint consideration of conflicts and interferences, spectrum switch delay and hops.