Location Management in Wireless Data Networks Abstract Location Management LM has become a diverse and broad field for research and Location Based Services LBS are the Application Layer of LM Research areas for LM include LM in Wireless Networks Ad hoc networks WiFi 802 15 WiMax and mostly cellular networks The integration of IP especially IPv6 into LM is the hottest topic of today This survey paper tends to introduce the reader to the latest research on LM in Wireless Data Networks and explore the various technologies under research and construction Table of Contents 1 Introduction 2 Location Based Services 2 1 Classification of LBSs 2 2 Applications of LBSs 2 3 LBSs in Research 3 Location Tracking and Updating Registration 3 1 Static Update Strategies 3 2 Dynamic Update Strategies 4 Location Finding Paging 4 1 Paging Schemes 4 2 Intelligent Paging Schemes 4 3 Intersystem Paging 4 4 IP Micro mobility and Paging 5 General Issues in LM 5 1 Security 5 2 Group Based LM 5 3 Distributed LM 6 LM in Wireless Networks 6 1 Heterogeneous Wireless Networks 6 2 Replication in Wireless Networks 7 LM in Wireless Mobile Ad hoc Networks 7 1 Soft LM Schemes 7 2 Hard LM Schemes 7 3 The use of TCP in MANETs 8 LM in WiFi 802 11 9 LM in Bluetooth 10 LM and IP Summary References List of Acronyms Fahd A Batayneh Page 1 of 21 fahd batayneh gmail com 1 Introduction Mobile wireless devices with wireless connection facilities are changing the way people think about the use of computing and communication These wireless devices can communicate with one another even though the user is mobile People carrying a mobile computer will be able to access information regardless of the time and their current position Over 100 million wireless Internet users were recorded as of September 2003 with the majority in Japan and Korea while fast growth rates were recorded in Europe Significant growth is expected in specialized mobile services such as driving directions traffic report tour guides and commerce services such as mobile shopping However Location Management LM will be an important issue in these situations because wireless devices can change location while connected to a wireless network New strategies must be introduced to deal with the dynamic changes of a mobile device s network address The ability to change locations while connected to the network creates a dynamic environment This means that data which is static for stationary computing becomes dynamic for mobile computing There are a few questions that must be answered when looking at a LM scheme What happens when a mobile user changes location Who should know about the change How can you contact a mobile host Should you search the whole network or does anyone know about the mobile users moves LM schemes are essentially based on users mobility and incoming call rate characteristics The main task of LM is to keep track of a users location all the time while operating and on the move so that incoming messages calls can be routed to the intended recipient LM consists mainly of 1 Location Tracking and Updating Registration A process in which an end point initiates a change in the Location Database according to its new location This procedure allows the main system to keep track of a user s location so that for example an incoming call could be forwarded to the intended mobile user when a call exists or maybe bring a user s profile near to its current location so that it could provide a user with his her subscribed services 2 Location Finding Paging The process of which the network initiates a query for an endpoint s location This process is implemented by the system sending beacons to all cells so that one of the cells could locate the user This might also result in an update to the location register As we can see the main difference between location tracking and paging is in who initiates the change While location tracking is initiated by a mobile host paging is initiated by the base system Most LM techniques use a combination of location tracking and location finding to select the best trade off between the update overhead and the paging delay LM methods are classified into two groups 1 Group one includes methods based on network architecture and algorithms mainly on processing capabilities of the system 2 Group two includes methods based on learning processes i e which require the collection of statistics on subscribers mobility behavior This method emphasizes the information capabilities of the network For LM purposes a wireless network usually consists of Location Areas LAs and Paging Areas PAs While LAs are a set of areas over which location updates take place PAs are a set of areas over which paging updates take place Usually LAs and PAs are contiguous but that s not the case always In addition a LA usually contains several PAs see Figure 1 1 Fahd A Batayneh Page 2 of 21 fahd batayneh gmail com Location Area LA Paging Area PA Figure 1 1 Location Areas vs Paging Areas As the size of the LA increases the cost of paging will also increase as more PAs are to be paged to find a called mobile host On the other hand reducing the size of a LA will increase the number of crossings per unit time Hence the cost of location update or registration will rise Both paging and location updates consume scarce resources like wireless network bandwidth and power of mobile hosts Each has a significant cost associated with it So LA planning is to be based on a criterion that guarantees the total signaling load which comprises paging and registration is kept under tolerable limits Therefore it is characterized by the trade off between the number of location updates and the amount of paging signaling that the wireless network has to deal with Having discussed briefly about LM updating and paging sections 3 and 4 go more deep into discussing updating and paging in more detail The next section talks briefly about Location Based Services LBS and their impact on LM The aim of the next section is to provide the reader with an overview as to why LM is necessary 2 Location Based Services Although Location Based Services LBS have been an issue in the field of mobile communications for many years no common definition has been devised for it The terms locationbased service location aware service location related service and location service have been used interchangeably These various terms have lead to several definitions of LBS Schiller04 defines LBS as services that integrate a
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