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:

1. 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;
2. CDMA-2000, used by the CDMA and IS-41-based 3G family; and
3. 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.