J. Parallel Distrib. Comput. 71 (2011) 1142–1153 Contents lists available at ScienceDirect J. Parallel Distrib. Comput. journal homepage: www.elsevier.com/locate/jpdc Fuzzy online location management in mobile computing environments Javid Taheri a,∗ , Albert Y. Zomaya a,b,1 , Mohsin Iftikhar b a School of Information Technologies, J12, The University of Sydney, Sydney, NSW 2006, Australia b Computer Science Department, College of Computer and Information Sciences, King Saud University Riyadh, Saudi Arabia article info Article history: Received 2 November 2010 Received in revised form 19 January 2011 Accepted 7 February 2011 Available online 16 February 2011 Keywords: Algorithms Fuzzy clustering Mobility management Performance abstract This paper presents a new approach, namely Intelligent Fuzzy Online Location Management Strategy (IFOLMS), based on Fuzzy clustering techniques to solve the mobile location management problem. Using a Fuzzy location estimator in this technique, mobile users’ past movements are used in making future paging decisions by the network. IFOLMS has the potential to lead to massive savings in the number of network signal transactions that must be made to locate users. Performance of the proposed approach has been measured by using several test networks; it shows promising results — around 50% reduction in network cost — when compared to many of the existing location management techniques (including GSM). Results also provide new insights into the mobility management problem and its associated performance issues. © 2011 Elsevier Inc. All rights reserved. 1. Introduction The next generation of wireless mobile networks needs to provide more complex services with high levels of quality of service. These networks will support a true combination of both real-time and non-real-time services, and also form a global personal communication network [1,11]. To support such a wide range of data transfer and user applications, mobility management must be considered when designing infrastructure for wireless mobile networks. Mobility management involves two processes: location man- agement and handoff management. Location management enables the wireless mobile network to discover the current point of at- tachment of a mobile terminal and direct calls to it; whereas, hand- off management enables the mobile network to locate roaming mobile terminals for call delivery and to maintain connection as the mobile terminal moves around. During the first stage of loca- tion management — known as ‘location registering’ or ‘location up- date’ — a mobile terminal periodically informs the network of its new access point and helps the network to authenticate the user and revise the user’s location profile. The second stage is ‘call deliv- ery’ or ‘paging’ in which the wireless mobile network is queried for the current position of a mobile terminal [1,11]. Mobility manage- ment requests are often initiated either by a mobile terminal move- ∗ Corresponding author. E-mail addresses: javid.taheri@sydney.edu.au (J. Taheri), albert.zomaya@sydney.edu.au (A.Y. Zomaya), miftikhar@ksu.edu.sa (M. Iftikhar). 1 A.Y. Zomaya is a visiting honorary professor at KSU. ment (crossing a cell boundary) or by deterioration in the quality of the signal received on a currently allocated channel (handoff). Fig. 1 shows an example of a GSM network in which cells are grouped into regions, each containing the whole allotted frequency spectrum. Each cell of the group uses part of the allocated frequency; the same frequency can be used in other regions by carefully considering the minimum distance between cells to avoid cross-talking [1,11]. As the demand for wireless services increases, the size of the cells will shrink and the reusability of the allocated frequencies will become increasingly critical to the viability of networks. As a result, network management, and consequently, location management will be a serious issue for future networks. Therefore, efficient techniques will be required to ensure the delivery of incoming calls, even for the tiniest of cells. In this paper, a fuzzy clustering technique combined with an intelligent algorithm is presented to solve the online (dynamic) location management problem for mobile networks. Using this technique, users’ previous movement patterns will be used to locate them while many of the traditional network transactions are saved. To present this approach, Section 2 provides a general overview of the location managements strategies including the concept of network cost. Section 3 concisely introduces fuzzy systems as the fundamental part of our approach. Section 4 presents the online location management strategy. A Simulation environment of our proposed algorithm, Discussion and Analysis, and Conclusion are presented in Sections 5–7, respectively. 2. The key issue: location management strategies Location management strategies can be categorised into two main schemes: offline (static) and online (dynamic). In offline 0743-7315/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jpdc.2011.02.003