As shown in Fig. 4, the gain G
ROAM
of the PLR scheme can be up to 70%, while
the G
PAGE
leads to higher paging time. However, the overall gain G
Total
can be up to
60%. It should be underlined however that in this evaluation we do not measure the
actual G
PAGE
,
in case the system had to locate a terminal in heterogeneous adjacent
network location management systems. The graphs also show that as the terminal
Call-Mobility Ratio (p) increases, the G
ROAM
and the G
PAGE
gain degrease. When the p
is small, the user roams more often. This leads to more frequent updates and larger
paging paths, so smaller G
PAGE
The G
Total
increases as more updates are local, and the HLR+ is not informed so
often. If we increase the C
IPLR
and C
PLR
values, the gain of the overall PLR algorithm
degrades faster with large T
IP
.T
P
value, compared with small T
IP
.T
P
value (Fig. 5).
This is due to the fact that larger thresholds T
IP
, T
P
lead to longer paths towards the
terminals, thus the system is more sensitive to the costs of inserting/updating a routing
entry in a PLR server.
5. Conclusions
Since a variety of mature wireless technologies are already available, a phased
approach may be deployed as evolving steps towards 4G. Future mobile terminals
will require to uninterruptedly roam from different in-building wireless networks, into
heterogeneous public picocellular/microcellular or even wide area macrocellular or
satellite networks.
Commercial public wireless LAN solutions however offer limited location
management capabilities compared to the traditional cellular networks. In order to
overcome these limitations, we introduced a Path Location Register (PLR) scheme for
Mobile Terminals Location Management. As has been shown in the performance
evaluation section, the proposed scheme reduces significantly the cost of mobile
terminal location update and paging, without dramatically increasing the system
complexity.
References
1. Th. Zahariadis, K. Vaxevanakis, Ch. Tsantilas, N. Nikolaou, N. Zervos, “Global Roaming in
Next Generation Networks,” IEEE Commun. Mag., Vol. 2, pp. 145-151, Feb.2002
2.] B.-N. Amotz, I. Kessler, M. Sidi, “Mobile users: To update or not to update?,” in Proc.
IEEE INFOCOM, vol. 2, June 1994, pp. 570–576.
3.] S. Tabbane, “Location management methods for third-generation mobile systems,” IEEE
Commun. Mag., vol. 35, pp. 72–84, Aug. 1997.
4. C. Perkins, “IP Mobility Support,” RFC 2002, Oct. 1996
5. A. Valko, “Cellular IP - A New Approach to Internet Host Mobility,” ACM Computer
Communication Review, January 1999
6. I.Akyldiz, W.Wang, “A Dynamic Location Management Scheme for Next-Generation
Multitier PCS Systems,” IEEE Trans. in Wireless Comm., Vol. 1, No. 1, pp.178-189, Jan.
2002.
7. A.Festag, H.Karl, G. Schaefer, “Current development and trends on handover design for All
IP wireless networks,” Technical University of Berlin, TKN-00-007, ver. 1.3, Aug. 2000
150