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GLOSSARY 847Fixed IP
NetworkUMTSBluetoothWLANFigure 5: Depiction of a personal area network (PAN).the entire network will use packet-switching techniques.
However, because there is not asingle3G standard upon
which to build 4G, there are significant challenges ahead.
To support such high data rates, significant advances
in baseband processing are necessary. One of the most
widely considered transmission schemes is multicar-
rier modulation (MCM), which uses many parallel sub-
channels to transmit information. MCM’s advantages in-
clude better protection against intersymbol interference
(ISI) and implementation efficiencies possibly using fast
Fourier transform (FFT) techniques. At least two differ-
ent types of MCM are being considered for 4G, including
multicarrier CDMA (MC-CDMA) and OFDM (recall that
OFDM is already used in several wireless LAN standards
such as 802.11a and 802.11g). Regardless of the multiplex-
ing scheme, techniques such as smart antenna and mul-
tiuser detection will become integral parts of the standard,
as they enable the technology necessary to support the re-
quirements of 4G. Additional information about 4G issues
may be found in Lu (2002), Lu and Berezdivin (2002), and
Mahonen and Polyzos (2001).ACKNOWLEDGMENTS
We thank the following colleagues for their assistance
with the authoring of this chapter: Jasmine Zan, Vlora
Rexhepi, Georgios Karagiannis, and Sonia Heemstra de
Groot. We also are very appreciative of all the insight-
ful comments from the reviewers of this chapter and the
guidance provided to us by Dr. H. Bidgoli.GLOSSARY
ATM A network technology designed to transport cells,
where unlike IP, cell sizes are fixed and circuit-
switching circuits are used.
Autonomous system (AS) A network or a group of net-
works operated by a common administrator.
CDMA A digital cellular technology that uses spread-
spectrum techniques to multiplex numerous concur-
rent connections.
Cellular network A wireless network that divides geo-
graphical regions into cells, to which subsets of avail-
able frequency bands are allocated.
Duplexing Transmission of data in two directions, from
node A to node B and vice versa.
Encapsulation The process of embedding an additional
network protocol on top of the existing one(s) possibly
for the purposes of tunneling.
Hop A connection between two adjacent network de-
vices such as a router.
Hypertext markup language (HTML) A formatting
language used in creating documents for the World
Wide Web.
Hypertext transport protocol (HTTP) A transport
protocol used in the World Wide Web to deliver doc-
uments to browsers.
Internet A global network of computers and smaller
networks.
Internet protocol (IP) A specification for data format
and addressing scheme used on the Internet.