Disraeli said, "Everything comes if a man will only wait." Well, 3G cell phones still aren't here, and certainly not due to a lack of effort. Handset and basestation manufacturers and carriers are struggling with a variety of cost, technical, and regulatory problems to reach the 3G nirvana. At the same time, they're trying to maintain and upgrade existing 2G systems to continue making a profit. You can be sure that 3G won't arrive on a specific date. In fact, 3G already exists in a few places around the world, but not on any grand scale.
It will be a few more years before we see 3G rolled out in the U.S. and Europe because it's complex and costly, and there's a real concern that consumers may not actually want or need it. We certainly won't see it in the U.S. until the spectrum shortage problem is addressed. The indecision of the U.S. Federal Communications Commission (FCC), the National Telecommunications Infrastructure Association (NTIA), and the U.S. Congress isn't helping U.S. deployment.
The lure of 3G technology is its potential. 3G phones promise improved digital voice communications, greater subscriber capacity, and fast packet-based data services like e-mail, short message service (SMS), and Internet access at broadband speeds. Most carriers also expect consumers to want location services, interactive gaming, streaming video, home monitoring and control, and who knows what else, while being fully mobile anywhere in the world.
But will subscribers really want or need 3G? What data services will subscribers actually lust after and pay for? Professor Nalin Kulatilaka at Boston University's School of Business says that carriers should focus on applications for mobile enterprise workers such as salesmen, claims adjusters, and other road workers.
The International Telecommunications Union (ITU) defines 3G, known as the Universal Mobile Wireless System (UMTS), as a packet-based system that achieves speeds of 144 kbits/s while fully mobile, 384 kbits/s during slow movement, and 2 Mbits/s from a fixed position. It implies full global roaming. In effect, 3G is a mobile broadband connection where even voice is Internet Protocol (IP).
The ITU/UMTS standards additionally define a specific wideband code-division multiple-access (WCDMA) radio. Other technologies also qualify as 3G under the ITU's definition. But overall, 3G means CDMA, which is clearly superior to the other digital standards, namely the GSM (Global System for Mobile) communications standard used worldwide, and the IS-136 time-division multiple-access (TDMA) standard used primarily in North America.
CDMA puts all users into a single wide-bandwidth channel and sorts them out by a pseudorandom coding process. This technique is far more spectrally efficient, as it permits more users and higher data rates in a smaller amount of spectrum than TDMA. Also, it's far more tolerant of the multipath and fading problems so common in mobile operation. The downside of CDMA is its incredible complexity.
CDMA also is a second-generation (2G) digital technology. Developed by Qualcomm, this CDMA standard is known as IS-95, or CDMAOne. It is widely employed in the U.S. but is not as widespread as TDMA.
The question is, how does a carrier move from current TDMA, or existing CDMA systems, to the new WCDMA? Three paths are emerging.
Three Paths To 3G
The first option is the path from existing IS-95 CDMA systems to Qualcomm's cdma2000 standard, which is backwards-compatible with IS-95. Available now, this new version of CDMA has been deployed in Korea and Latin America. The first systems are expected to show up in the U.S. early this year.
When used with the 1X en-hancement, cdma2000 permits a data rate of 153 to 307 kbits/s in the currently assigned 1.25-MHz voice channels. This can later be upgraded to 1X-EV-DO, which promises up to 2.4 Mbits/s in a 1.25-MHz channel. Because this technology is available now, you must wonder why more carriers aren't taking this relatively fast, easy path to 3G. Verizion, Sprint PCS, Bell Mobility, and Leap are just beginning to go this way.
Most carriers opt for the second path to 3G of working toward ITU/UMTS WDCMA. This standard uses 5-MHz wide paired channels in a frequency-division duplexed (FDD) scheme to provide a 2-Mbit/s data rate. A compatible time-division duplexed (TDD) version is available for those with insufficient spectrum.
This road to WCDMA is by way of GSM systems. All of Europe and a huge percentage of the rest of the world, including the U.S., uses GSM TDMA systems. UTMS WCDMA has been defined as the natural upgrade from GSM. Virtually all GSM carriers will take this route with multimode phones and basestations.
Along the way, most carriers are adopting an intermediate solution called General Packet Radio System (GPRS). This so-called 2.5G system adds a packet-based, always-on feature to existing GSM systems. GPRS steals time slots from the eight available in a GSM frame to carry packet data using the existing GMSK modulation. It's a fast, cheap, and easy to implement software upgrade. It can achieve practical data rates in the 28- to 56-kbit/s range with a maximum theoretical rate of 112 kbits/s--not bad for e-mail and short messages, but marginal for Internet access, browsing, gaming, or video.
Another 2.5G enhancement to GSM, enhanced data rates for global evolution (EDGE), gives an even faster data rate by adding eight-level modulation (8PSK) to achieve up to 384 kbits/s. Many carriers plan to follow the GSM-GPRS-EDGE path to WCDMA. Some even plan to skip the slower GPRS phase and go directly to EDGE. Conversion is relatively easy in most systems by replacing cards in the basestations.
Another option is to convert from the existing IS-136 TDMA systems to GSM, then follow the GSM-GPRS-EDGE path to WCDMA. The GSM system is simply overlaid with the IS-136 system, so spectrum can be shared until full conversion. This seems like an expensive and time-consuming proposition, but both AT&T Wireless Systems (AWS) and Cingular are well on their way toward this conversion.
Today is clearly the age of 2.5G systems, specifically GRPS, EDGE, and cdma2000 1X. Carriers seem to be using 2.5G to give them breathing room and find out which data services will sell best. But 3G is here now. Korea and several Latin American countries use Qualcomm's cdma2000 system. Japan's NTT DoCoMo launched its WCDMA Freedom of Mobile Access (FOMA) 3G system last October. A WCDMA 3G system is also in full operation on the Isle of Mann.
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