S.L. Lee, H.-C. Lin, and P.-X. Kou (Taiwan)
: Bypass pointer, Call-to-Mobility Ratio (CMR),
Hierarchical Location Databases, Location Management,
Personal Communications Services (PCS).
In this paper we propose an efﬁcient tracking strategy, called
the Pre-Caching strategy, for hierarchical database architec
ture in Personal Communication Services (PCS). The main
goal of our strategy is to focus on reducing 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 characteris
tic of locality. The Pre-Caching strategy keeps a callee’s by
pass 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 point
ers. The purpose of setting the value of a threshold is to
avoid updating and reading location databases frequently
when users may 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 point
ers. Through mathematical cost analysis and experimen
tal evaluation, we demonstrate that the Pre-Caching strat
egy without employing any users’ proﬁle information can
reduce more trafﬁc impacts than the traditional × and