Research On Spectrum Allocation Algorithm In Cognitive Radio Networks

With the development of radio communication technology, spectrum resource has been more widely employed, and the scarceness of wireless spectrum hampers the continual development of wireless communication. Cognitive radio (CR) technology is a revolutionary technology of wireless mobile communication, which is considered as a new approach to solve the problem of the shortage of wireless spectrum. Wireless users can use CR technology to sense the environment smartly, searching for available spectrum resources and access spectrum dynamically, so that the efficiency of spectrum is improved and the capacity of wireless communication system is increased. Due to the spectrum resources in cognitive radio networks are changed by the different time, the different geographical location and the different authorized user activities, the peculiar spectrum allocation algorithm in cognitive radio system has become the research hotspot. This paper further studies the dynamic spectrum allocation algorithm, analyzing the research background, describing the definition and the functions of cognitive radio. And the key technology of cognitive radio and research status are described in detail. Corresponding algorithms are proposed and the performance of these algorithms is verified through computer simulations.Firstly, aiming at the single cell in a cognitive radio network, spectrum allocation algorithm is studied, based on the Graph Theory, a dynamic spectrum allocation algorithm based on the node priority is proposed. Combining the idea of Best Available Multiple Access (BAMA), this algorithm defines the priority of both channel and the node of cognitive users. The pre-allocation is based on the standard of the maximum bandwidth in collaborative method in CSGC algorithm. If some cognitive users that spectrums are not allocated to are found in the network, their priorities will be revised, and their spectrums will be re-allocated. The corresponding simulation results show that the improved algorithm can not only be very good to meet the needs of users, providing high distribution efficiency, but also better reflect the spectrum allocation fairness.Secondly, studies are based on the spectrum sharing algorithm, aiming at the overlapping multi-cell cognitive radio networks, according to the auction theory, and combining the technology of Spectrum Overlay and the technology of Spectrum Underlay together, a hybrid spectrum sharing algorithm is put forward. This algorithm modeled the cognitive network as a base station and a plurality of auction stations, considering both the benefits of the base station and the requirement of auction stations, using the technology of Spectrum Overlay within the coverage of CR network to reduce the interference to the main users and using the technology of Spectrum Underlay outside the coverage of CR network to improve the utilization of channels. The simulation results show that this algorithm can obtain high efficiency of allocation and high rate of system.Thirdly, in order to verify the proposed algorithms, a cognitive radio network simulation platform is built through the OPNET simulation software, establishing the corresponding process model, node model and network model, mainly simulating and verifying the dynamic spectrum allocation algorithm based on the priority of nodes in single cell cognitive radio networks. Compared the system performance under different algorithms and before or after the new algorithm, different requirements of the system are satisfied, and the utility of spectrum allocation is improved.