Cognitive Radio Ad Hoc Network Routing Algorithms

With the rapid development of wireless communication technologies, wireless spectrum resource has been growing more and more needful and scarce, while it hasn’t been fully utilized because of the fixed spectrum distribution and exclusive spectrum usage. As a new technology, cognitive radio can automatically detect surrounding environment, intelligently adjust system parameters, and improve spectrum utilization in space, frequency and time without interfering with primary users.There are two kinds of spectrum shared access modes in cognitive radio:overlay mode and underlay mode. In overlay mode, secondary users can access the spectrum which is not occupied by primary users temporarily. When primary users re-occupy, cognitive users should stop its transmission and quit that licensed spectrum immediately. Overlay mode focuses on spectrum detection (including the detection of spectrum holes and primary users), which causes minimum interference to primary users. In underlay mode, secondary users can use the same spectrum with primary users at the same time, under the condition that the interference generated by the cognitive transmitters should not exceed threshold which the primary users can tolerate. Underlay mode can use licensed spectrum with wider bandwidth and higher spectrum usage. In this paper, we focus on the routing of secondary users in underlay mode.The routing protocol in cognitive radio is different from traditional routing protocols (like minimum hops, shortest path, maximum throughput, or minimum delay) as the secondary users can not interfere with the primary users both in time and space. In this paper, we choose interference as routing metric, and divide interference into intra-system interference and inter system interference. Based on the existed ad hoc interference routing protocol, we improve its interference weights, and propose new routing protocols corresponding to minimize inter system interference (minimum interference to primary users) and the joint interference of intra-system and inter system (minimum intra-system interference under the condition that inter system interference is below the interference threshold).In cognitive radio networks, secondary users are intelligent to maximize their own benefits, which choose to cooperative only when it brings them profits. We use game theory to solve selfish behaviors of rational users. Game theory is a way to study the interaction and inter-balance of multi-strategy users in order to maximize the overall benefits or utilities. Pricing-based method is one of the game theories to analyze the interaction and stimulate cooperation. A low cost truthful energy-efficient routing protocol is proposed in cognitive selfish ad hoc networks. The costs are defined as function of the interferences to primary user and their remaining energy, and use VCG (Vickrey-Clark-Groves) mechanism to pay for the relay nodes, it can be proved that declare type truthfully is a dominant strategy for secondary users. Simulation shows that this routing protocol can implement low cost truthful energy-efficient in cognitive selfish ad hoc networks and achieve better performance compared with existing routing protocols.In the last part, the research results of this thesis are concluded and the future research plans are proposed.