Researches On Routing Protocols Of Cognitive Radio Ad Hoc Network

Along with the rapidly increasing requirement and application of wireless communications, the radio spectrum resources become more and more precious. However, the existing radio spectrum resource management and allocation policy makes the current radio spectrum efficiency at a very low level:most allocated radio spectrum has not been fully utilized, and some hot radio spectrum resources are overloaded. In order to resolve the problem of lack of radio spectrum resources and its low usage rate, some people have proposed the idea of cognitive radio. The basic idea of cognitive radio is:cognitive radio users can't interfere with the main users who own radio spectrum resource. But cognitive radio users could choose some main user's unused radio spectrum resource to transmit data. In this way, we can improve radio spectrum efficiency.This article carried out a deep research in routing algorithms and corresponding protocols of cognitive radio networks. The paper begins with a brief introduction to the basic concept of cognitive radio, cognitive radio network characteristics and the development of the status at home and abroad. Then, it has simply analysis a few on-demand routing protocols of Ad Hoc networks and some routing protocols proposed for cognitive radio networks, which clarified the issues to be addressed in this article. First, we proposed an improved algorithm IMAODV to improve performance of AODV routing discovery process. Then, through analysis and summary to cognitive radio networks, we proposed an improved routing protocol CNAODV adapted to the characteristics of cognitive radio network, which was based on IMAODV.CNAODV introduces on-demand routing mechanism to divide the whole routing mechanism into three parts:routing discovery, routing response and routing maintenance. The destination node has completed the work of allocating radio spectrum resource, and realizes the fuction of radio spectrum resource sensing. We have done some simulations to test performance of the CNAODV in the NS2 simulation platform. The simulation results show that the improved cognitive radio routing protocol has less routing load and higher throughput than original AODV protocol. CNAODV can consider both spectrum handoff delay and hops in the data transmission process. CNAODV adapt better to cognitive radio network than AODV, it has provided a solution for cognitive radio networks.