Research On Dynamic Spectrum Allocation And Routing Protocol In Cognitive Radio Networks

The speeding development of wireless communication technology not only provides people with increasingly available bandwidth but also makes itself present a trend of being heterogeneous, wide-band, high-speed in data transfer rates and diversified in communication service. However, radio spectrum is a kind of non-renewable natural resource and its effective use is of extremely significance. The fixity of current management model for spectrum allocation and the inefficient use of authorized band thrust wireless communication into severe challenges. Meanwhile, the dynamic changes of the heterogeneous network environment aggravate the conflict between the demand for wireless communication services (such as mobile telecommunications, television broadcasting, public safety and so on) and the scarcity of spectrum resources, thus gravely limiting the deployment and operation of existing as well as future wireless communication networks and posing unprecedented challenges to the development of wireless communication networks.To solve the problems mentioned above, there emerges a new focus in wireless communications research– the cognitive radio technology. Since the conception of cognitive radio was put forward, it has attracted wide attention and considerable researches. However, the current study of scholars, research institutions and universities at home and abroad mainly concentrates on the investigations of spectrum sensing and dynamic spectrum allocation.The first two chapters of this paper introduce the generation background of cognitive radio, the current development of cognitive wireless network and its relevant research hotspots which mainly consist of the key technology of cognitive radio, the architecture of cognitive wireless network, relative research institutions, and standardized organization. The first two chapters also state the network environment, the purpose and significance of this research and finally point out the range of this study (dynamic spectrum allocation and routing algorithm), targeted problems and expected objective.The third and fourth chapters, taking multi-hop cognitive radio networks as background basis, respectively explore the dynamic spectrum allocation algorithm for MAC layers and routing algorithm for network layer of the secondary users. The dynamic spectrum allocation algorithm in the third chapter aims at increasing the authorized channel utilization of primary users grounded on priority-based access mode. First, the different priorities for secondary users are modeled and established in accordance with the characteristics, the arrival rate and the cooperative sensing profit of the their business; second, the priorities are modeled based on the utilization and data transfer rate of authorized channel after its cooperative sensing. And then, a priority-based cognitive multi-channel (PCM-MAC) access strategy, which proves to be fairer for the secondary users, is proposed and designed based on the two models mentioned above to ensure the fair access to idle authorized channel for secondary users with different types of businesses or different amount of businesses, thus effectively improving the spectrum efficiency. The network layer routing algorithm in the fourth chapter, based on existing MANETs routing protocol OLSR, proposes and designs a multi-path routing protocol (LCM-OLSR) for secondary users in multi-hop cognitive radio networks, which balances load to different paths and conducts cross-layer optimization by adopting link layer MAC protocol. To put it another way, this design takes into account both the routing choice and spectrum availability to reduce end-to-end delay, to increase packet delivery rate as well as to reduce the routing overhead and so on.