I 1
_I - cx- I
U
(Continuedfrom page 30)
mize a channel allocation plan, and
therefore QoS and revenue. The last
chapter contains an extcnsion of the
algorithm, proposed in Chaptcr 6, to
cellular networks.
Although the title suggests a rather
broad subject, in reality thc focus is
quite narrow. The book deals with very
specialistic knowledgc of performance
management and presents the results of
the authors’ research, so it could he dif-
ficult to understand for readers without
sufficient knowledge about telecommu-
nications networks and network man-
agement issues, and without an
appropriate mathematical background.
Someone can treat the first three
chapters of the book (almost half of its
volume) as a concise introduction to
performance management issues; howev-
er, for specialists the second part should
be of greater interest. Prediction of traf-
fic in the real network could help in its
optimization, increasing satisfaction of
subscribers and overall revenue. The
method proposed by the authors deals
with multiplexed video traffic, and was
not tested with voice and other low-pri-
ority data traffic. In my opinion, in the
current market situation, it is very diffi-
cult to predict if video traffic will really
he the most common type of traffic in
next-generation networks. For example,
I believe that real-time video on demand
will not be the most common application
in next-generation networks. Currently
available compression techniques allow
a 2-hr film with quality more than suffi-
cient for the size of current and future
screens of mobile terminals to he put
on a standard CD, using 650 Mbytcs of
memory. Flash memory modules avail-
able on the market can already store
256 Mbytes of data, and their size
allows us to put one or two into cur-
rently available mobile phones. This
means that from a technical point of
view video could be downloadcd (or at
least partially buffered) into the mcmo-
ry of a mobile terminal as low-priority
data and then displayed for the user.
Such an approach could change what
we currently imagine about the type of
traffic in next-generation networks.
The algorithms proposed in Chapters
6 and 7 are designed to optimizc rev-
enue from the network without decreas-
ing QoS. The proposed framework
allows one to optimize the whole mobile
architecture using traffic measurements
from different points. Calculations are
executed from time to time, so the
authors do not expect any problems with
their complexity; however, these algo-
rithms were not tested on real networks.
BOOK REVIEWS
Performance management of net-
works will be more and more important
because it allows higher revenuc with-
out investing in vcry expensive infra-
structure. The algorithms proposed in
the book are part of current research in
this area, but their utilization in real
networks will need a lot of further effort
during simulation, implementation, and
verification. While reading this book
everyone should remember that the
proposed framework is still in a very
early phase and will need theoretical
and practical verification from precon-
ditions through the specific algorithms
to behavior in unexpected situations.
MOBILE SATELLITE COMMUNICATION
NETWORKS
BY RAY E. SHERIFF AND Y. FUN HU. JOHN
WILEY AND SONS, 2001. ISBN: 0-471-
72047-X
REVIEWER: EYLEM EKlCl
The book Mobile Satellite Communi-
cation Networks presents a very well
organized summary of satellite-based
communications systems. The technical
parts of the book focus basically on
three aspects: constellation design,
satellite link characteristics, and net-
working issues with an emphasis on
integration with terrestrial systems.
Thc hook not only addresses the
technical issues related to satellite net-
working, but also gives an overview of
developments in the commercial world.
Existing and proposed satellite commu-
nications systems outlined in the book
help bridge the gap between the theo-
rctical and practical aspects. Overall,
the readcr is presented with the big pic-
ture on satcllite communications, where
the basics of the technology, and the
past, present, and future of satellite
communications are blended in a
unique balance in nine chapters.
The first chapter of the book gives
an outline of mobile communications
system evolution. The purpose of this
chapter is to introduce the cellular and
wireless network infrastructures satcllite
systems are envisioned to complement.
The basics of cellular systems, and the
properties of the four generations of
cellular networks as well as the wire-
less telephone standards are summa-
rized in varying depth.
In the second chapter the existing
satellite systems are outlined. Following
the common properties of satellite com-
munications systems, mobile satellite sys-
tems are examined in three categories.
The orbital and operational properties
of each individual mobile satellite system
is presented along with its history and
the latest status of the system.
U
I
- . ~ .
Constellation characteristics and
orbital parameters of the satellite sys-
tcms are introduced in the third chapter.
First, physical laws governing the move-
ment of satellites are summarized, fol-
lowed by the conventions uscd to refer
to the position of a satellite in space.
Orbital perturbations caused by the Sun
and Moon, Earth’s shape, and atmo-
spheric drag are analyzed quantitatively.
Lastly, satellite constellation design con-
siderations are introduced with a fucus
on constellations with circular orbits.
The fourth chapter is dedicated to
satellite channel characteristics. In par-
ticular, charactcristics of two types of
channels are considered: channels
between satellites and mobile stations,
and channels between satellites and
fved Earth stations and gateways. Prop-
erties of these two channel types as well
as different approaches to modcling
them arc summarized in this chapter.
The radio link design considerations
are presented in Chapter 5 . The pre-
sented radio link design is based on the
link budget method, which considers
the influence of various aspects such as
satellite payload characteristics, fre-
quency, and transmission power. The
modulation and coding schemes pro-
posed for satellite radio links are sum-
marized next. Finally, the multi-access
techniques that can be used on the
satellite radio links are presented.
The network procedures in mobile
satellite networks are presented in the
skth chapter. First, the GSM and GMR
signaling protocols are introduced. Next,
the mobility management problem is
analyzed with a focus on location and
handover management schemes. Finally,
research management considerations in
satellite networks are presented.
Chapter I addresses integration con-
siderations of terrestrial and satellite
mobile networks. The integration of the
satellite networks with three types of
terrestrial networks is considered:
PSTN, GSM, and 3G wireless networks.
The integration issues with the GSM
network are emphasizcd in this chapter,
for which the integration at all layers is
described in detail.
The last two chapters are dedicated
to the future of satellite communica-
tions systems. The eighth chapter pre-
sents a market analysis for
satellite-based systems. T h e role of
satellites in different service categories,
the satellite market, and the future
market forecast are described, and the
results presented. Finally, the last chap-
ter presents a view of the future of
satellite communications. Among other
issues, future satellite network architec-
(Continued on page 34)
32 IEEE Communications Magazine May 2002