Mobile User’s Location Management using Bloom Filter Pragyan Acharya #1 , Sudhansu Sekhar Singh *2 # School of Electronics Engineering, KIIT University Bhubaneswar, India * School of Electronics Engineering, KIIT University Bhubaneswar, India Abstract— Cellular networks have become so pervasive that they resulted in some undesired consequences like increase in computational cost, delays and system overloading. Various Location Management (LM) schemes such as static LM and dynamic LM have been adopted for cost reduction. Basing upon the cellular network’s geographic layout, location update is done in static LM. Dynamic location update schemes are based on the status and state of the mobile. Although dynamic LM is efficient in cost reduction, its effectiveness is limited because most of the theories are in the infancy stage and fail to suit the reality of life. Hence most wireless systems employ static LM. This paper proposes a method for the use of a paging mechanism which has used the technique of Bloom filtering in the Never Update strategy of static location management to select cells to be paged and thereby helps to reduce the polling cost to a greater extent. Numerical results show that the use of bloom filter improves the never-update strategy of static location management scheme. . Keywords— Mobile Computing, Static Location Management, Never Update strategy, Always update strategy, Bloom Filter. I. INTRODUCTION Ability of providing mobility is the most important characteristic property of cellular system. The total number of worldwide mobile telephone subscribers is predicted to pass five billion by 2011 constituting about 72% of the total population. This increases the complexity of the system needed to manage all the users. Unlike a wired connection where the signals have been passed through guided medium to the correct destination, wireless system doesn’t enjoy the luxury of knowing the location of the user. Hence it has to incorporate ways to trace out the user and subsequently to send the data into the system and thereby to enable a mobile system access the services of the system it is connected to. The process of keeping track of the present or last known location of the mobile is called as Location management (LM). Cells are grouped into Location Areas (LA). LA can be of same size or different size due to geographical constraints. The users move inside these areas based on some pre-defined standards [1]. When a user receives a call the network pages the cells of a LA to locate the user. Frequent Location Updates reduce polling costs, but with consumption of time and energy from all the updates. Less frequent Location Updates will store less information about user’s location. It has the advantage of reducing computational overhead no doubt but has the disadvantage of higher paging cost. Hence a trade off has to be made between all these important considerations [2][3]. Location management system has been divided into two parts- static LM and dynamic LM. In static LM scheme the cellular network’s geographic layout determines when the location updating needs to be done. Dynamic location update schemes are based on the status and state of the mobile. Although dynamic LM is efficient in cost reduction, its effectiveness is limited because most of the theories are in the infancy stage and fail to suit the reality of life. Static Location management incurs greater cost, but most cellular networks use this scheme. This paper proposes the use of Bloom Filter for local prediction of the cell in a Location Area where the user resides. Prediction of the exact cell location where the user is present makes the system page only that cell instead of all the cells in a Location area. This paging strategy supports Mobile Computing and Communications. II. BASIC CONCEPT A group of cells constitute a single Location Area. These cells are assigned a location area identification value. Each base station in the LA broadcasts its identification (ID) number in a periodic fashion over a control channel. The Mobile Stations (MS) that are attached to the Base Station (BS) within the LA are required to listen to the control channel for the LA ID. If the LA ID changes, the MS has to send a location update message to the new base station. The VLR database will receive the updated information forwarded by the base station [4][5]. All the cells in the new LA will be paged whenever there is an incoming message. This forms the basis of static Location Management. It is of two types such as always-update and never-update strategy [6]. A. Always Update Every time the user moves into a new cell the always- update strategy performs a location update. Paging is not required to locate the user when an incoming call arrives. Pragyan Acharya et al, / (IJCSIT) International Journal of Computer Science and Information Technologies, Vol. 2 (3) , 2011, 1127-1130 1127