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Emerging Technology: Are We Better Off Without 3G?

By Andy Dornan

06/03/2003 8:00 PM EST

URL:

http://www.networkmagazine.com/shared/article/showArticle.jhtml?articleId=10300091

A few years ago, proponents of third-generation (3G) mobile networks told us that networkers would have abandoned copper and fiber by now. They imagined a world without wires, in which cell phones displaced land lines, and people surfed the Web or accessed their company networks from a cafe, airport, or park.

They were right about the applications, but wrong about the technology. Though cell phones are more popular than ever and surfers are connecting to the Internet wirelessly, there's little connection between the two. Instead of accessing 3G networks through futuristic converged devices, most wireless workers reserve their cell phones for voice and use laptops with Wi-Fi (IEEE 802.11) cards for data. With Wi-Fi already both faster and cheaper than 3G, many networkers see the latter as irrelevant.

Not surprisingly, the cellular industry disagrees. Though slower than Wi-Fi, cellular networks do have some advantages: They can cover a much wider area, they provide true mobility, and they're more secure. While cell phone users can move around without worrying which base station they're routed through, Wi-Fi users need to find and connect to a particular hotspot. Cell phone companies hope that Wi-Fi and 3G will complement each other, with 3G coverage filling the gaps between hotspots, and 3G security filling the gaps in the 802.11 standard.

This is a nice vision, but one that relies on two unproven assumptions: that people want or need to access the Internet while in motion (as opposed to stationary and in a hotspot), and that 3G data will be affordably priced. So far, both are in doubt. Building out 3G networks is expensive, and companies already close to bankruptcy aren't going to sell data connectivity at a loss.

Most carriers in Western countries have already upgraded their existing networks to handle packet-switched data and higher speeds. Some are even calling these upgrades "3G," though they don't meet the ITU's original definition. According to the ITU, 3G refers to a system that provides average data rates of at least 144Kbits/sec in each direction. (The first two generations were analog and digital voice.) Others are more honest, referring to their upgrades as "2.5G" and planning to offer genuine 3G service later in 2003.

This is true even in the United States, which has traditionally lagged behind other countries in wireless networking, but is catching up. American carriers may even be learning from mistakes made elsewhere. The 3G available in the United States won't offer data speeds quite as high as those in Europe, and by the ITU's standards, some systems might not officially be 3G at all, but this could be a good thing.

Though few networkers would deny that higher data speeds are good, high speed entails high cost. This is often enough to destroy the business case, especially when Wi-Fi offers even higher speeds at a much lower cost. Recognizing that they can't compete by selling raw bandwidth, carriers are instead trying to package it into value-added services. The problem for 3G is that most of these work just as well over the cheaper 2.5G.

CELL DIVISION

There are several paths to 3G, as shown in the figure on page 31. This theoretically gives users a choice, though that choice is nearly always made for us by carriers and by geography. The carriers in turn are constrained by their governments, and by the need for compatibility with their existing networks.

By the end of 2002, the world's cellular operators had a total of about one billion customers, almost all of whom are connected to some form of 2G network. Around 700 million are using GSM, a system developed by European governments during the 1980s. Contrary to the claims of anti-GSM lobbyists seeking to capitalize on anti-French sentiment, the GSM standard wasn't developed in France, though it's named after a French committee (Groupe Speciale Mobile). This was later "backronymed" to the Global System for Mobile Communications, reflecting the technology's spread throughout the world-including to the United States, where it's used by two of the three largest cellular carriers.

The remaining 300 million cell phones are more or less divided evenly between systems commonly referred to as Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA), though both of these are really technical terms that describe radio technology, not standards.

Of the two, CDMA is the most advanced. Some form of CDMA air interface is used in most 3G networks, as well as in all 802.11b wireless LANs. However, when people talk about CDMA, they're usually referring to networks based on the IS-95 standard, which was developed by Qualcomm and is now licensed to other manufacturers. It was first introduced in the United States, though the most advanced CDMA services are offered in South Korea.

Likewise, GSM uses a TDMA air interface, though hardly anyone refers to it as such. When the cellular industry says TDMA, it usually means systems based on the ANSI-136 standard, which was intended as a simple digital upgrade to the American Mobile Phone System (AMPS), the 1G technology which is still the only wireless coverage available in some rural areas of the United States.

No new TDMA networks are now built, and carriers that use the technology are gradually replacing it with CDMA, GSM, or 3G. However, many mobile data users still find it attractive, as it was the first 2G technology to benefit from packet-switching. By April 2003, NTT DoCoMo's i-mode service had more than 38 million users running over Japanese TDMA networks, and it still signs up about 30,000 new customers each day.

PRIVATE PARTS

The popularity of i-mode is a stark contrast to the failure of Wireless Application Protocol (WAP), the mobile data system offered by carriers elsewhere. Launched at the peak of the Internet bubble, WAP was promoted as the "wireless Web." Expecting a similar user experience to the real Web, consumers were disappointed to find a simple hypertext information system.

A text-only browser is theoretically useful for providing access to business applications, but the original version of WAP had other weaknesses: It didn't include end-to-end security, and relied on a very limited type of Extensible Markup Language (XML). Some companies were also hyped into building "m-commerce" sites aimed at customers, when most are better served by mobilizing employee-facing applications such as e-mail.

Many cell phones now include WAP 2.0, which overcomes most of the original version's problems. It's still more limited than the regular Web, but is backward-compatible with both the original WAP and i-mode, and supports Secure Sockets Layer (SSL) security. Setting up an intranet server that provides access through WAP is now a realistic possibility for many organizations. All the large wireless carriers also offer services that can provide mobile access to e-mail and other applications.

Most cell phone systems now include their own messaging system, which usually isn't integrated with e-mail. The most popular is the Short Message Service (SMS). Originally designed as a way for GSM operators to send remote updates to phones, SMS was never intended as a commercially viable service, but became an unexpected success in Europe during the late 1990s.

SMS's weaknesses are legion. It only supports uppercase English, user input is through the eight alphanumeric keys of a phone, and it must use spare capacity on the signaling channel. This makes it extremely vulnerable to spam (see "The Most Damaging E-mail Virus of All," Off the Wires, December 2002) and not very reliable. According to tests performed by KeyNote Systems (www.keynote.com), an average of one in every 20 SMS messages sent across U.S. networks gets lost in transit.

Worst of all, each message is limited to only 160 characters when using GSM, and even less when using some other technologies-about the length of this sentence. To cram the most information into the short space, users have had to invent a new language reminiscent of telegrams and personal ads.

Test messaging does have one huge advantage: very low cost. This has made it particularly popular among children and teenagers, who have a lot of free time but can't afford to run up large phone bills. It isn't really a serious business tool, and until recently wasn't even used by adults. Some U.S. operators are trying to attract Internet users by partnering with the big Instant Messaging (IM) companies-AOL, Yahoo, and MSN-but so far with limited success.

Despite its low cost, SMS is very profitable for carriers. Most are hoping that messaging's popularity will continue into 3G, and are thus promoting the new Multimedia Messaging Service (MMS). Unlike SMS, this uses the main data channel of a 2.5G or 3G network, with the maximum message length expanded to 500Kbytes. If used for text, that's more than any user could hope to read before the phone's battery runs out, let alone type using a numeric keypad.

MMS can theoretically carry any kind of data, so it could be used for e-mail with attachments. However, charging issues and problems with spam mean that carriers are still pitching it mainly as a way for communicating between phones, not between phones and the Internet.

Until e-mail integration arrives, MMS will have few business uses except industrial espionage. The most popular application so far is photo sharing, with many new phones including tiny digital cameras that can be used to transmit photographs to friends. In the U.K., the presence of camera phones is already having an impact on privacy. The owners of venues such as swimming pools, art galleries, and casinos are banning all cell phones, out of fear that casual chatters may actually be taking photographs and uploading them to the Web.

UNIVERSAL SET

Both WAP 2.0 and MMS rely on a 2.5G or 3G network. For GSM, the obvious upgrade is the General Packet Radio Service (GPRS), a packet-switched technology that almost every GSM operator has already rolled out. It uses the same Physical layer as GSM, so cellular towers don't need to be replaced.

So many GSM networks are now using GPRS that the two technologies are becoming synonymous: The GPRS standard is controlled by the GSM Association (www.gsmworld.com), and whenever a carrier announces it's building a new GSM network, it usually means GPRS. About half of all GSM phones shipped now include GPRS as standard.

The lack of a new Physical layer makes GPRS easy to deploy, but it also means that the technology doesn't actually add any capacity to GSM networks. Initial claims that it would increase GSM's data speed by a factor of eight-to more than 100Kbits/sec-proved wildly optimistic.

A full-speed GPRS terminal would have to transmit at up to eight times the power of a regular GSM data card, draining the mobile device's battery eight times as fast and consuming eight times as much bandwidth. It would also have to transmit and receive simultaneously, requiring two separate radios. To make devices simpler, real GPRS devices are limited to about half the theoretical speed when receiving, and even less when transmitting.

Though slower than originally advertised, GPRS is often sufficient for applications running on cell phones, whose small display limits the amount of content they're able to receive. It isn't enough for real mobile computing, so European operators have long planned to upgrade to a 3G technology known as the Universal Mobile Telecommunications System (UMTS) or Wideband CDMA (W-CDMA). The UMTS standard is designed to allow dual-mode phones to roam onto GSM and GPRS networks, though the networks themselves aren't compatible.

GSM carriers upgrading to UMTS must install new radios at their base stations, and must often lease new land and obtain new planning permissions since the base stations need to be closer together than those used for GSM. They also need new radio spectrum, which European governments made a lot of money auctioning to telecom companies during the telecom bubble.

UMTS can reach very high data rates-theoretically as high as 2Mbits/sec using current terminals, and up to 10Mbits/sec in the latest version of the standard, which employs a technology called High-Speed Downlink Packet Access (HSDPA) and is sometimes described as "3.5G." (See "Fast Forward to 4G?" March 2002.) However, these data rates are shared among every user in a cell, and require a clean, interference-free signal. Real performance is around 300Kbits/sec, which isn't as good as the hype, but still fast for anyone accustomed to regular cell phones.

TDMA doesn't have an obvious upgrade path, so most operators are taking the GSM route instead. Japan's NTT DoCoMo went straight to UMTS, deploying the first real 3G service in May 2001. However, high prices and poor coverage have made attracting customers difficult. In its first two years, the service signed up about 200,000 users-the same amount its older 2G-based i-mode gets in a week.

OVER THE EDGE

Unlike European and Japanese regulators, the FCC didn't allocate any spectrum to UMTS. Instead, AT&T Wireless and Cingular Wireless are replacing their TDMA networks with GPRS, though they plan to move to UMTS if and when spectrum becomes available.

Anyone wanting UMTS in the United States is likely to face a long wait. With no new spectrum and little customer demand, Cingular hasn't set a timetable for its move to the worldwide 3G system. Neither have T-Mobile, the other large GPRS carrier, or any of the smaller regional operators. Some carriers are experimenting with a partial implementation of UMTS as a fixed wireless system, but deployments and commercial trials are still limited to a few areas (see "Unwiring the Last Mile," January 2003).

The one U.S. carrier that has committed to rolling out full-scale UMTS is AT&T Wireless, and it doesn't have a choice: NTT DoCoMo has invested $10 billion in the company, which will have to be repaid unless AT&T Wireless makes UMTS available in San Francisco, Seattle, Dallas, and San Diego by the end of 2004.

Instead of UMTS, most U.S. operators are betting on Enhanced Data Rates for GSM Evolution (EDGE), an upgrade to GPRS that does include a new Physical layer. It's fully backward-compatible with GPRS (and GSM), using better radio modulation in existing spectrum to increase network capacity. It can increase data rates by a factor of up to three, but this requires good radio reception.

European carriers originally intended EDGE to be an intermediate step between 2.5G and 3G, thinking that UMTS would take a long time to develop and that, as something based on the tried-and-true GSM technology, EDGE would be much simpler. They were right about the former, but not the latter. With no demand for wireless data and spectrum licenses that obligate them to provide UMTS coverage, they ignored EDGE and concentrated on UMTS.

Though European operators overlooked EDGE, the manufacturers of cellular equipment didn't. The largest, Nokia, has quietly been building the technology into all of its GSM base stations for nearly two years, and announced its first EDGE phones in March 2003. Many GSM base stations in the United States are less than two years old as they're a recent upgrade from TDMA, so they're already capable of EDGE. Once phones that support it start shipping, the networks will be switched on.

Operators in other parts of the world are also building out EDGE, and even some European operators are planning to adopt it. Carriers like it because it remains fully compatible with GSM, but adds capacity, which can be used for voice as well as data. The technology's average throughput may not meet the ITU's original definition of 3G (see table), but it comes close, and the industry is promoting it as a "3G" technology. For most cell phone users in the world, including customers of GSM carriers in the United States, it's the closest they'll get.

2.5G and 3G Technologies

Technology

Hyped Date Rate

Real Data Rate

(Approximate)

Status

GPRS

115.2Kbits/sec

30Kbits/sec

Available worldwide; U.S. carriers include AT&T, Cingular,
and T-Mobile.

EDGE

472Kbits/sec

100Kbits/sec

Planned by North and South American GPRS operators later
in 2003 and 2004.

UMTS

2Mbits/sec

300Kbits/sec

Available in parts of Japan and Europe; planned by AT&T
in three U.S cities by 2005.

CDMA 1xRTT

144Kbits/sec

60Kbits/sec

Available from Sprint and Verizon in much of the U.S.,
as well as throughout Japan and South Korea.

CDMA 1xEV

2.4Mbits/sec

300Kbits/sec

Available from Monet Networks in parts of the U.S., with
Sprint and Verizon planning wider coverage later in 2003 and 2004.

HSDPA

10Mbits/sec

Unknown

Planned "3.5G" upgrade to UMTS; already built into some
European networks and planned in Japan.

CDMA 3xRTT

10Mbits/sec

Unknown

Potential upgrade to CDMA 1x systems that makes them compatible
with UMTS and enables HSDPA.

802.11b/a/g

54Mbits/sec

1.5Mbits/sec

Available worldwide, but in very localized areas.

Wireless Wait. Neither CDMA 1xMC or GPRS meet the ITU's original 144Kbits/sec definition of 3G. However, they're at least as fast as dial-up (about 50Kbits/sec) and much faster than circuit-switched cellular networks (14.4Kbits/sec or less).

CODED MESSAGES

Like GSM, CDMA systems have a straightforward upgrade path, through a family of systems collectively known as CDMA2000 (see figure). CDMA's route to true 3G is actually slightly easier than GSM's, because there's never a need to rip out existing networks. Like the move from GPRS to EDGE, every upgrade provides an increased-capacity Physical layer, and is backward-compatible with existing phones.

The end-route of CDMA-2000 was originally intended to be 3x Radio Transmission Technology (3xRTT), so called because it ties three CDMA radio channels together. The radio channels used by regular IS-95 CDMA are relatively narrow, so the theory was that putting three of them together would provide compatibility with W-CDMA, and hence with UMTS. However, lack of spectrum means that no operator has actually announced plans for 3xMC, and innovations in radio technology mean that 3G speeds can be reached without it.

The first step in the CDMA2000 route is 1xRTT, a system pioneered in South Korea and now used by Sprint PCS and Verizon Wireless in the United States. Both are promoting it as "3G," though by ITU standards, it's clearly 2.5G. However, it's better than rival 2.5G technology GPRS. Even Nokia, once the greatest supporter of GPRS, admits that 1xRTT is at least 50 percent faster, averaging speeds of about 60Kbits/sec. Phones can even burst to as high as 144Kbits/sec, though this depends on a clear radio signal.

CDMA carriers like 1xRTT because, like EDGE, it increases voice capacity as well as data speeds. Users also seem to like it, even when compared to UMTS, which is true 3G.

In Japan, the two systems are competing head-to-head, with NTT DoCoMo offering UMTS and rival KDDI offering 1xRTT. So far, 1xRTT is the clear winner. Launched in March 2002, it signed up more than six million customers in its first year-about twenty times as many as UMTS managed in twice that time. The applications are similar and mostly consumer focused-MMS, games, and subscription content-but although UMTS is faster, 1xRTT is much cheaper and offers better compatibility with existing networks.

Carriers are already planning the next stage in CDMA's evolution, known as the Enhanced Version (1xEV). This offers comparable speeds to the early versions of UMTS, but still uses only a single radio channel (see table). Like EDGE, it depends on clear reception, so actual performance is highly variable.

The United States's first 1xEV network was launched in October 2002 by Monet Mobile Networks (www.monetmobile.com), a regional operator that serves parts of Minnesota, Wisconsin, and the Dakotas. The national CDMA carriers will also offer 1xEV later in 2003, though only in some areas initially. Verizon Wireless, for example, says it will have networks up and running in San Diego and Washington D.C. Sprint PCS hasn't yet announced firm plans, but has been conducting trials since last year.

CDMA carriers will have to go to 3xRTT if they want to take advantage of the very high data rates offered by HSDPA. However, with applications such as MMS running just as well over 2.5G, few are rushing to do this.

Part of 3G's problem is poor coverage, something that will improve as more networks are built out. Even measured by land area, DoCoMo's Personal Handyphone System (PHS), a network of cordless telephony hotspots, still offers better coverage than UMTS. DoCoMo expects UMTS coverage to overtake PHS sometime in 2003, but Wi-Fi may be growing even faster.

Though Wi-Fi services are (justifiably) criticized for poor coverage, in most parts of the world it's still much easier to find a Wi-Fi hotspot than a 3G network. For 3G to be successful, this will have to change.

ANDY DORNAN is senior editor of Network Magazine and author of The Essential Guide to Wireless Communications Applications, ISBN 013-0097-187, published by Prentice Hall. Reach him at [email-masked].