| Ad Hoc network does not rely on pre-erected infrastructure. It forms the network rapidly and the network is easy to manage, so it is often used in a variety of harsh environments and the situation for special occasions. However, it often encounters the problem of scarce spectrum resources. On the one hand, with the development of wireless communication technology, people require communications with higher quality and much more traffic. On the other hand, spectrum efficiency of the licensed spectrum is very low, resulting in a lot of waste. Caused by this paradox, the experts propose the cognitive radio technology. It improves spectrum efficiency by dynamic spectrum access. Greater attention is paid to the research of cognitive radio Ad Hoc network.Based on hierarchical clustering structure of CRAHN network, inter-cluster communication problem has been studied. Firstly, the system is analyzed from the two aspects of cognitive radio technology and Ad Hoc network. Cognitive radio technology, multi-user access technology, spectrum management and cooperative relaying communication are all included in this paper for more information about access technology.Secondly, the proposed cooperative relaying scheme is suitable for this paper. The application scenarios of relay communication are defined under this system model. A cooperative relaying communication selective scheme based on residual energy and CSI is also proposed for one of the application scenarios to find the most suitable relay node.Then different inter-cluster relaying schemes are proposed for different application scenarios. Link establishment process between cluster heads and relay node is also provided.The problem of channel switching and the choice of time slot and other key issues is detailed.Finally, the scheme is realized on the DSP platform by C language. The software design and workflow, the frame design and more details of rely node are shown in this paper, and then test in CCS software. |
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