셀룰러망에서 계층 구조를 이용한 위치 관리 기법에 관한 연구

Abstract

According to the rapidly evolving technologies of wireless networks and improved performance of computer hardware, future computer systems are going to be ubiquitous environments that make it possible to easily access desired information anytime and anywhere irrespective of physical location of users. Especially, the number of subscribers in personal mobile communication is rapidly increasing recently. After all, the location management of MS (Mobile Station) plays an important role in mobile communication systems. There have been considerable research activities in reducing a cost of location management. Among them, a scheme which reduces the updating cost of location without increasing a paging cost, has mainly researched. A signaling costs a great deal when to update information of HLR(Home Location Register) rather than VLR(Visitor Location Register). The proposed location management scheme using hierarchical structure focuses on signaling traffic to update location by reducing the number of update in location information of HLR. This paper proposes an analytic model which can measure average updating cost and a method to determine size of SLA(Super Location Area) which minimizes the updating cost using this model. Accordingly, this scheme using location management scheme using hierarchical structure can reduce a waste of network resource caused by frequent location updates in the GSM(Global System for Mobile Communication). However, the update rate of HLR is reduced and the update rate of VLR is increased by geometric progression as the SLA size becomes larger. Finally, this paper proposes the method to find the size of hierarchy in which minimizes the total updating cost in cellular network, considering the update rate and cost of HLR and VLR. The performance evaluation shows that the more the number of cell, the larger size of hierarchy. In other words, as the number of cell becomes larger. load concentrated on HLR should be appropriately distributed to VLR to maintain the minimum update cost in whole network.