November 1999
Decisions Confront Evolution To 3G Wireless
BY PRODIP CHAUDHURY
Third-generation or “3G” wireless systems, based on the global system for
mobile communications (GSM) platform, comprise the next iteration of mobile communications
services. With first-generation analog and second-generation (2G) digital systems
established throughout much of the world, the growing demand for high-speed,
data-intensive wireless services — such as Internet access and video conferencing
— is now driving the development of 3G systems.
International Mobile Telecommunications-2000 (IMT-2000) is the basic global 3G standard
being developed by the International Telecommunications Union (ITU). IMT-2000, an evolution of 2G systems, proposes a
family of 3G systems interoperating through standard interfaces. The European Union’s
IMT-2000 family member is known as Universal Mobile Telecommunications System (UMTS). It
is being developed under the Third Generations Partnership Project (3GPP) whose membership includes the standards organizations
of Europe (ETSI), the United States (T1), Japan (TTC and
ARIB), and Korea (TTA).
IMT-2000 family members will have unique radio interfaces. Though many radio interface
technologies have been submitted to the ITU for IMT-2000 membership, three radio
technologies have emerged as most prominent. These are:
- The Wideband Code Division Multiple Access (W-CDMA) in Frequency Division Duplex (FDD)
and Time Division Duplex (TDD) modes, the radio technologies used by the UMTS family;
- CDMA-2000, used by the CDMA and IS-41-based 3G family; and
- 136-HS, used by the TDMA and IS-41-based 3G family.
Lately, there has been an ongoing attempt by operators and vendors through the
operators harmonization group to find commodities and easy interoperability between W-CDMA
and CDMA-2000 radio technologies, and GSM and IS-41-based networks.
POLITICAL AND MARKET PRESSURES
The U.S. operators that opted for narrowband CDMA in their 2G systems adopted
“cdma2000” as the 3G standard, because it ensures backward-compatibility with
their existing networks. Similarly, the operators who used GSM systems have opted for
UMTS. The European operators, given their long-standing commitment to GSM, are unlikely to
opt for any technology that is incompatible with their existing investments. Indeed, GSM
networks in 133 nations currently are delivering services to more than one-third of the
world’s wireless subscribers. With such an extensive GSM footprint around the globe,
the network operators who chose GSM technology for their 2G systems obviously are
well-positioned to integrate 3G technology within their existing infrastructures.
Consequently, multi-mode handsets will be required to ensure backward-compatibility with
all existing networks and global roaming among 3G systems.
In the face of all this geopolitical and technological uncertainty, vendors are
designing and producing 3G equipment for the various technologies in question. Network
operators will begin launching 3G services in the early part of the next decade.
WHAT DOES “3G” REALLY MEAN?
The ongoing evolution to 3G must resolve still more questions. One stems from the
emergence of an additional technology that significantly boosts GSM’s current
data-transmission rate of 9.6 Kbps. Enhanced data rates for GSM and TDMA evolution (EDGE)
technology, expected to be available in 2001, will offer data speeds of 384 Kbps in
outdoor vehicular operations. EDGE-equipped networks will be more than capable of
supporting multimedia wireless applications.
This so-called “interim” technology is prompting different people to come up
with different ideas about what 3G really means. When the ITU started its 3G project back
in 1995, the idea was to bring together many competing technologies in a unified global
standard that would ensure seamless global roaming among diverse wireless networks,
outdoor vehicular data speeds of 384 Kbps, and indoor stationary data speeds of 2 Mbps.
Multi-mode handsets that would work with all three of IMT-2000’s specified air
interfaces theoretically would solve the global-roaming issue.
EDGE-enhanced networks clearly will meet the ITU’s objective for 3G outdoor data
rates. The pending availability of EDGE raises the question of where exactly EDGE-enhanced
networks will fit in the generational hierarchy of wireless technology. For many GSM
operators, the integration of EDGE technology with their existing networks translates into
“2G-Plus” capabilities, while for TDMA operators, it translates into
“3G” capabilities. In either case, operators of EDGE-equipped wireless networks
may have a tough time justifying an investment in any more advanced
“3G-compliant” IMT-2000/UMTS technology that might emerge.
POLITICS IN EUROPE, DELAYS IN THE STATES
To make an uncertain situation even more so, EDGE raises a significant question about
spectrum allocation, especially in Europe. Even before the ITU adopted the IMT-2000
standard, member nations in 1992 allocated a 230-MHz block of spectrum in the 2-GHz band
for 3G systems. Many European operators now fear that if they deploy EDGE, and thus can
satisfy IMT-2000 data-speed requirements, they won’t be eligible for a chunk of the
IMT-2000 spectrum. Understandably, they do not want to preclude their own access to that
invaluable resource.
The United States lags behind Europe in more ways than the 3G spectrum issue. U.S.
regulators have yet to tackle the 3G spectrum-allocation issue. And, U.S. wireless
operators have still another barrier confronting them on their road to 3G — the lack
of public understanding of the benefits of such advanced wireless systems.
As most European and some U.S. operators were deploying 2G digital systems based on GSM
technology, many others were forced to delay their 2G deployments because of a technology
war over the TDMA and CDMA radio interfaces. Neither one emerged as the clear victor, but
the delay caused by that technology war means that many U.S. operators still are rolling
out their 2G networks. Other than U.S. road warriors who need high-speed wireless access
to corporate intranets now, most American users are about five years behind their European
counterparts in appreciating the applications and benefits of advanced wireless services.
APPLICATIONS AND USER-FRIENDLY HANDSETS
Eventually, U.S. operators and subscribers will catch up with their European counterparts.
Yet in all regions of the world, the ultimate success of 3G systems depends on
applications. Many industry observers believe, for example, that electronic commerce will
be “the killer application” that fuels widespread demand for 3G wireless
services. That may turn out to be the case. However, people are likely to opt for 3G
services, be they for e-commerce, Web browsing, or other high-speed data applications,
only if those services are priced affordably and if 3G handsets are easy to use.
Despite all these uncertainties, 3G wireless systems will emerge. It is equally clear
that they’ll appear in different flavors at different times — in different parts
of the world.
Prodip Chaudhury is director of product line management and systems engineering for
Siemens Information and Communication Networks, Inc.
Siemens Information and Communication Networks offers public network service providers
digital central office switching equipment, access network solutions, broadband switching
systems, wireless solutions, end-to-end multimedia solutions, Internet solutions, network
management products, and transmission products.
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