Research On Mobility Management In Cognitive Radio Communication System

Spectrum resource is not renewable natural resources. With the rapidly development of wireless communication technology and popularization of information technology in all areas, application of the traditional fixed spectrum allocation strategy can not meet people’s growing demand of the spectrum. To solve the problem of the terrible shortage of wireless spectrum resources and highly underutilized of authorized spectrum, the researchers put forward the concept of cognitive radio. Cognitive radio is a hot technology based on software radio, it can take the initiative to understand the radio environment around, find a spectrum hole, through the opportunity to access the free spectrum, and sharing spectrum resources with the primary users. To avoid the interference to the primary user, when the presence of primary users can be perceived by cognitive radio users, cognitive radio users should immediately withdraw from the current frequency, namely spectrum handoff, this brings a spectrum mobility management issues. The goal of the development of communication system is to meet people’s demand for getting communication service at anytime, in anywhere and by anyway. Mobility management is one of the necessary supporting technologies.This paper first introduces the knowledge of cognitive radio, pointed out the key technologies and capabilities of the cognitive radio; then introduced the two main elements of mobility management for traditional wireless communication systems combining illustrate mobility management scheme of cellular mobile communications network, location management and switch management, Concretely introduce the handoff scheme and process while mobile terminal moves under different scenarios; Finally, against diversity of mobility triggering events, this paper proposes a new spectrum mobility management framework, Under this framework, the problem of spectrum mobility management and spectrum handoff are studied in mobility management of cognitive wireless communication system from the traditional wireless communication system, focus on the handling of the cognitive radio communication system to deal with all kinds of mobility triggering events, mainly includes the spectrum mobility brings of appearance of primary user and user mobility and the of problem cell selection.On the study of the mobility management of cognitive wireless communication system, this paper will look the cognitive wireless communication system based on the Ethernet connection, cognitive users and primary users coexist within multiple cells as the cellular mobile communication network with cognitive function, and defines the mobility management functional entity related to the cognitive radio communication system. To improve the mobility performance of the cognitive user, This paper introduces the new conceptions of based area and extended area in cognitive cellular mobile communication network architecture, which improve user mobility performance; through the spectrum pool, reducing the difference of spectrum availability; spectrum mobility management scheme proposed by the networks can make the proper band and the target cell for mobile users based on the current cell spectrum usage and random connection model; user mobility management by selecting the appropriate type of handoff mechanism to reduce the communication quality dropping based on lower overhead, forming an effective spectrum mobility management scheme. Simulation results show that use of this mobility management framework and methods, compared with the conventional methods, can get greater cell capacity and support better performance of mobility.