Research Of Adaptive Bandwidth Allocation Mechanism In Cognitive Radio Network

The Research are supported by the National Natural Science Foundation "Research on spectrum detection based on spectrum utilization statistic" (NO.60772110), Huawei Technology Foundation "Research about cognitive radio in MAC Layer" and Field Foundation of Beijing University of Posts and Telecommunications.As a revolutionary smart spectrum sharing technology, CR receives more and more interest within these years. In the CRN, CR users can automatically sense the wireless environment, and then access the CRN within the spectrum which had been allocated to the license users but not occupied right now. CR can significantly improve the spectrum utilization. But CR users always occupy fixed bandwidth in the research on spectrum allocation algorithm. If CR users could adaptively adjust their transmission bandwidth, the spectrum utilization would be effectively improved. The adaptive bandwidth allocation mechanism in the spectrum allocation algorithm is researched in this paper.This paper described the subject background, briefly introduced the basic concepts and standardization status, and particularly analyzed the spectrum allocation types and algorithms firstly. In the next third and fourth chapters, the adaptive bandwidth allocation mechanism and its simulation method in the spectrum allocation technology in CRN were studied.In the third chapter, the adaptive bandwidth allocation mechanisms were researched according to fixed bandwidth allocation problem. The adaptive allocation mechanism based on forced termination mechanism and the adaptive allocation mechanism based on handoff queuing mechanism were proposed. Theoretical analysis and simulation show that the adaptive bandwidth allocation mechanisms effectively improve the channel utilization of the system. In the fourth chapter, a simulation method of the adaptive bandwidth allocation mechanism is proposed. This simulation method uses the event scheduling which is variable step. The simulation result and error analysis show that this simulation method is feasible.