Research On Spectrum Sensing And Spectrum Access Strategy In Cognitive Radio Network

The traditional radio spectrum allocation strategies is allocating fixed spectrum band to each authorized wireless system, which, however, causes spectrum resource utilization rate be extremely low and is inapplicable in today's rapidly developed wireless communication. Thus, cognitive radio as an innovative technology which can make unauthorized networks loan spectrum for data transmission from existing authorized networks arose. This paper studied spectrum sense and spectrum share algorithm of cognitive radio network to reduce channel sensed time and improve utilization of idle spectrum.The first two chapters of this paper firstly introduced the background, developing history and latest research progress of cognitive radio both at home and abroad. Then emphatically summarized spectrum sense and spectrum sharing technology includes some existing great performance spectrum resources management algorithms.Based on the theoretical basis of the first two chapters, the paper then analyzed spectrum utilization surveys and spectrum hole measurement reports which published by SSC. According to the analysis results of spectrum hole's distributed characteristics, this paper proposed a simple spectrum sense strategy based on the idle probability of channel. The strategy use channel statistics idle probability to get an optimal channel sense sequence. The simulation results show that this strategy greatly improves the secondary user's sense efficiency.Then we studied spectrum allocation algorithm of cognitive radio, and a kind of adaptive sensing spectrum allocation strategies was proposed. In this strategy, secondary user first conducts selfish independent sense in each transmission cycle. If detected idle channels meet its own needs, it accesses these channels. Conversely, it would broadcast sense result to the neighbor nodes base on the cooperation detection principle. This kind of adaptive way not only ensures secondary user which carried out the sense can access channels in a prioritized approach, but also improves the whole throughput of secondary network by cooperative detection. In addition, we considered the hardware restrictions of cognitive transceiver in process of spectrum sense and proposed the concept of window sense based on that. In the process of spectrum allocation, multiple secondary users can access idle primary channels for transmission through adding channel information to the control packets. Theory and simulation results proved this strategy can significantly improve the throughput of secondary network and utilization of idle channel.