Research On Routing Protocol For Cognitive Radio Networks

As a solution to the problem of spectrum scarcity the cognitive radio technology has become a popular research topic in recent years with its adaptive dynamic spectrum access ability. The corresponding routing protocol has to be designed when the cognitive technique applies to the wireless network. Routing protocol is in the middle layer of network. It needs adapt to the changing network environment and meet the requirement of the upper layer protocols. The dynamic spectrum environment and the opportunities channel access characteristic of cognitive network bring a certain difficulty to the design of the routing protocol. To improve the adaptability and robustness of cognitive routing, the following researches are carried:1. A real-time channel allocation routing protocol was proposed aiming at the dynamic spectrum environment of cognitive radio Ad-hoc network. In this protocol, by introducing the IN MESSAGE packets, the adjacent cognitive users could exchange their spectrum information during data transmission so that they could achieve the real-time channel allocation to adapt to the variability of their available channel set. Simulation results show that the real-time channel allocation routing protocol had a higher packet delivery radio and fewer number of route rebuilding times. It is more suitable for dynamic wireless environment of cognitive radio networks.2. To ensure the route stability and reduce the route latency between the cognitive users, a stability and delay based routing protocol was proposed. In the protocol the concept of stability factor was introduced,only the paths which meet the stability constraint can be the candidate routes. Then the transmission delay was used as a metric to select the best route from those candidate routes. Based on the detail analyze of the latency and route stability in cognitive radio Ad-hoc networks, the proposed channel allocation and routing selection strategy was realized by adjusting the AODV routing protocol. Simulation results show that the proposed protocol has a better performance on route stability and end to end delay under different source-destination distances and different primary user activities.3. In cognitive radio networks, to reduce the overhead and decrease the energy consumption and ensure the spectrum efficiency. A spectrum aggregation and cluster based routing protocol is proposed. In the proposed protocol node clustering and spectrum aggregation are performed based on the spectrum sensing result. The spectrum aggregation algorithm is aiming at minimizing the transmission power. The routing is based on clustering result, and data transmit is on the basis of the spectrum aggregation. Simulation results show that in the networks with larger node numbers the proposed protocol has lower routing overhead and fewer energy consumption while guaranteeing the packet delivery ratio.