The Research And Implementation Of Convergence Node Based On CRAHN MAC Layer

Due to the independent of pre-erect infrastructure, high networking speed and flexible management characteristics, Ad Hoc network is widely used in the harsh environment and for particular case. With the development of information industry and Internet service, people have more and more demands on the communication speed, resulting in the scarcity of spectrum resources. Cognitive radio Ad Hoc network, as a combination of cognitive radio and self-organizing networks, solves both of the problems. This paper proposes a hierarchical clustering CRAHN network structure and MAC layer scheme with a sink node.First, the paper researches the formation of the sink node and cluster heads in the hierarchical clustering network model, and presents two different election algorithms for them, which improves the network’s stability and reliability. A time synchronization algorithm is also designed to realize high-precise synchronization and reduce its overheads. Both of the algorithms increase the robustness and accuracy of the CRAHN.Then, a hybrid access scheme of multi-channel MAC protocol is designed for the hierarchical clustering CRAHN. The paper gives a detailed introduction to the super-frame structure,the design of CCC_Beacon frame, the allocation and management of CFP timeslots, the login and management of nodes, the allocation of TNI, the management of frequency pooling and so on.Finally, the MAC layer scheme with a sink node is achieved on the DSP platform using the C language. The realizations of receiving and transmitting frames, CCC_Beacon frame, switching the sink node, and managing the spectrum functions are focused in this paper.