Research On Intelligent Sensing And Power Control Method In Cognitive Radio Network

As a revolutionary smart spectrum sharing technology, cognitive radio (CR) can significantly improve the spectrum utilization, which can be able to seek and use in a dynamic way the frequencies for network access by autonomous detection of vacant bands in radio spectrum. The key problem in cognitive radio network is how to use spectrum sensing technology to find the spectrum hole and identify the license users. And how to achieve the optimum coexistence between SU and PU at the same frequency using transmission powers control (TPC) technology to guarante the PU's communication required by the quality-of-service (QoS).The creative work of this paper is mainly manifested in the improvement of intelligent sensing algorithm and power control method in cognitive radio network.In this paper, the subject background and significance of CR is presented. And the development of the status quo at home and aboard is described. The chief introduction on key technology in cognitive radio is made. The conclusions and analysis on current spectrum sensing technology are made. This paper focuses on methods for feature sensing of primary bands in IEEE 802.22 WRAN systems. This method facilitates the detection of signals by increasing the number of cyclic period or the duration of cyclic period used in the calculation of the correlation function as well as reducing the delay. Simulations in fine sensing by characteristic of primary user signal are presented. The algorithm proposed can promote the improvement of the performance of system spectrum sensing and protection of license user as well as make full use of spectrum resource.Secondly, a novel setting and access control method of adaptive sensing threshold based on power detection of the primary user (PU), on the basis of the analysis of the coexistence model between PU and SU, is proposed. The mathematical and practical simulations are made, and results analysis of the proposed mechanism in IEEE 802.22WRAN is carried out. The sensing threshold calculated by power detection of PU, not only maintains constant probabilities of missed detection and false alarm, but also obtains the optimum performance of spectrum sensing. The optimal SU's transmission power, adaptively according to sensing threshold, enables both SU and PU to coexist in the same channel without interfering each other.Finally, the multi-group TOA (Time of Arrival) and AOA (Angle of Arrival) provided by two base stations are measured based on the single reflect statistics channel model under NLOS environment. The paper initials new sensing method using scatter information around mobile user to locate the primary user. A new algorithm combined neural networks with the weighted centroid algorithm to achieve primary user's location is proposed. The system location model and the algorithmic principle of location are described. The location results of primary user are applied into adaptive sensing algorithm and analysis of the impact on detection performance towards location error in the proposed mechanism. The algorithm proposed can restrain NLOS error effectively and further improve localization accuracy. In order to adaptively adjust sensing threshold for cognitive radio and lower threshold error, the analysis and comparison of various kinds of localization algorithm error affect sensing detection performance. The result shows the current localization algorithm improves detection performance and obtains more exact probability of spectrum coexistence.