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Journal of Information Science and Engineering, Vol. 20 No. 4, pp. 617-641 (July 2004)

A Lazy Caching Location Strategy with Bypass
Pointer in PCS

SingLing Lee, Hwa-Chuan Lin and Pei-Xian Kou
Department of Computer Science and Information Engineering
National Chung Cheng University
Chiayi, 621 Taiwan

In this paper we propose an efficient tracking strategy, called the Precache strategy, for a hierarchical database architecture in Personal Communication Services (PCS). The main goal of our strategy is to reduce the overloads of a PCS system in the following two situations: (1) when a callee receives calls frequently, and (2) when a user crosses many registration area (RA) boundaries with the characteristic of locality. The Precache strategy keeps a callee°¶s bypass pointers when he/she moves around neighboring RAs. A threshold to predict and confine the roaming regions is used to estimate the trade-off of maintaining bypass pointers. The purpose of setting the value of a threshold is to avoid updating and reading location databases frequently when users move around in certain fixed regions (RAs). We also discuss how to set the threshold value to determine a user°¶s roaming regions and where to set the bypass pointers. Through mathematical cost analysis and experimental simulation, we demonstrate that the Precache strategy, without employing any users°¶ profile information, can reduce more traffic impacts than the traditional Basic and Caching strategies.

Keywords: bypass pointer, call-to-mobility ratio (CMR), hierarchical location databases, location management, personal communications services (PCS)

Full Text (•Ģ§Śņ…) Retrieve PDF document (200407_03.pdf)

Received October 18, 2001; revised June 2, 2003; accepted July 8, 2003.
Communicated by Jean-Lien C. Wu.