Evolution to Generationext

Today, there are a variety of mobile phone standardsoperating throughout the globe. Consumers cannot travel from one country toanother without having multiple phones in tow to comply with these multiplestandards. However, a new standard is being developed–one that not only bringsus closer to the concept of global roaming, but also provides a biggerdata/voice pipeline to accelerate Internet-enabled mobile devices. This emergingstandard, now in development and soon to begin initial deployment, is known as3G.

The term 3G is short form for Third-Generation wirelesstechnology: a technology that will help bring together two of the world’sfastest-growing industries–mobile communications and the "wireless"Internet. Advanced 3G handsets will allow users to access music, photos andvideos, while on the move. The long-term goal of 3G technology is to create aunified worldwide standard that allows for global roaming. However, with thenumerous standards in existence today, reaching this goal will definitely be achallenge.

Where Have We Been?

The first generation of cellular phones was based onFrequency Modulated (FM) analog technology. Most countries developed their ownsystems, but while these phones allowed for roaming within one region, theycould not be used across different countries.

This was especially problematic in Europe, where each countryhad its own standard. To address this problem, the European TelecommunicationsStandards Institute (ETSI) created the first Second-Generation (2G) digitaltechnology called Global System for Mobile Communications (GSM). GSM wasmandated in the early 1990s as the digital technology for all of Europe.According to the market research firm Dataquest, GSM has become the most widelydeployed digital cellular technology, with over 250 million subscribers.

Japan deployed a different technology–Personal DigitalCellular (PDC). The systems were designed to increase the voice capacity of theoriginal analog systems, as the First-Generation analog were becoming capacitylimited due to the explosive growth of the wireless industry. PDC is a TDMA-basedtechnology, operating in the 800 MHz and 1500 MHz frequency bands.

While Europe and Japan worked to standardize on one digitaltechnology, the US allowed for multiple technologies, including IS-95 CDMA (orcdmaOne), IS-136 TDMA, and GSM. Frequency was auctioned to the highest bidder,and wireless carriers choose the 2G technology they believed would provide thebest business opportunities. Unlike GSM in Europe and PDC in Japan, the US lacksa dominant 2G technology.

To get the world on track for the deployment of 3G standards,the International Telecommunications Union (ITU) started the IMT-2000 project–thetechnical framework for 3G. The goal of this project is to establish oneworldwide global standard for the next-generation of mobile communications.System definitions require the support of voice and data communications, withdata rates of 144 Kbps for high-speed mobility, 384 Kbps for low-speed mobility,and 2 Mbps for fixed-location terminals. The frequency bands 1885-2025 MHz and2110-2220 MHz were set-aside for the IMT-2000 project.

In 1998, the ITU accepted proposals for the IMT-2000 radioaccess network. They received 10 different suggestions for 3G terrestrial-basedRadio Transmission Technology (RTT). Over the last year and a half, these 10standards have been consolidated into five ITU-approved standards. Of these,three have emerged as logical extensions to existing 2G networks: Wideband CodeDivision Multiple Access (W-CDMA), TDMA-EDGE, and cdma2000.

Where Are We Now?

Today, the various 2G technologies are attempting to migrateto the 3G standards. The migration path from GSM to 3G is largely dependent onwhat spectrum is available. If operators can secure a new spectrum in theIMT-2000 band, the 3G technology of choice is W-CDMA. This is the radio accesstechnology selected by ETSI for wideband radio access to supportthird-generation multimedia services. If a new spectrum is not secured in theIMT-2000 band, the migration path is to the Enhanced Data for Global Evolution(EDGE) system. EDGE is a new air modulation technology, considered a"stepping stone" to 3G wireless communications. This technology can beoverlaid on top of an existing spectrum to support data rates up to 384 Kbps.

Regardless of what technology a GSM operator deploys, thefirst step to 3G implementation is the deployment of General Packet RadioService (GPRS). The GPRS data services are an enhancement to the GSM corenetwork, which allows for the delivery of packet data to the mobile phone. Itutilizes the existing circuit-switched GSM network infrastructure for voicetraffic, while adding a new packet-switched network for data traffic.

In Japan, the 3G technology of choice is W-CDMA. Japan plansto have commercial deployment in major metropolitan areas during 2001, withcountrywide deployment by 2003. One of the key drivers for Japan being the firstto deploy 3G is the lack of capacity in the existing 2G spectrum. With thegrowth of data services, this capacity shortage will become more acute. Bydeploying 3G technology, both voice and data services can be accommodated in ahighly spectral-efficient
system.

In the US, Canada, and much of Latin and South America, PCSlicences have already been awarded to wireless operators, overlapping the ITU’sspectrum for IMT 2000 deployment. This limits the migration paths for North andSouth American operators to those technologies that can be overlaid on theexisting second-generation systems.

Operators deploying cdmaOne in the Americas have one of themost clearly defined migration paths to the cdma2000 third-generation standard–astandard that will enable phone manufacturers to develop Internet-readyproducts. cdma2000 will allow the creation of wireless phones supporting voice,high-speed data and video, as well as digital e-commerce and real-time audio andvideo streaming.

The operators can overlay a 1x RTT cdma2000 system, whichsupports data rates up to 384 Kbps, on top of their existing cdmaOne networks.With future expansions to 3x RTT, 2 Mbps will eventually be supported. These newcdma2000 systems can support both existing cdmaOne mobiles and next-generationcdma2000 mobiles within the same frequency spectrum. Upgrades to the networkinfrastructure take place in the baseband processing units within thebasestation. No changes are required in the RF chain since the bandwidths andthe peak-to-average ratios of the signals change significantly between cdmaOneand cdma2000 on the forward transmission path. Since the final stage poweramplifier is the most expensive single element of a basestation, this is a bigadvantage for cdmaOne operators.

The 3G migration path for the IS-136 TDMA market is EDGEtechnology. EDGE is designed to increase network’s data capability to support384 Kbps, and it can be overlaid on top of an IS-136 network. In order for anIS-136 operator to deploy EDGE, they must first clear at least 800 KHz ofspectrum in order to deploy three 200 Kbps EDGE channels, and have 100 KHz guardbands between the EDGE channels and the 30 KHz IS-136 channels. The advantage ofEDGE for IS-136 TDMA operators is that it allows roaming between European EDGEoperators and the Americas’ IS-136 EDGE operators.

The disadvantage is, at least initially, that the IS-136operator must reduce their present voice capacity by setting aside voicespectrum for EDGE data-only capability.

Where Are We Going?

3G technologies open up a whole new world of possibilitiesfor wireless operators, now that wireless networks are not restricted tovoice-only systems. The data capabilities of 3G systems allow operators to takeadvantage of the explosive growth potential the Internet has provided totraditional wireline operators over the last five years. For example, considerthe convergence of digital camera technology and mobile phones, which allows fornear-instantaneous swapping of photo files.
Or, the inclusion of MPEG3 players in the mobile phones, which enables MPEG3downloads and playback
on the go.

Most likely, 3G systems will not achieve a single globalstandard anytime soon. The only way for a phone to work in multiple parts of theworld will be through multi-band and multi-mode technologies. Phone manufacturesare under increasing pressure to support multiple technologies and multiplefrequencies within the phone handset. In the US, for example, almost all newphones must support both a signal digital technology and the first-generationAMPS analog system. This also demands that semiconductor manufacturers producesolutions with higher levels of integration to maintain the same small formfactor of phones consumers want today.

There is still a lot of work to be done before 3Gtechnologies are tested during the IMT-2000 trials in 2001. However, one thingis certain: just as no one could have predicted 10 years ago the revolutionaryimpact the Internet would have on our lives, future applications and usage of 3Gtechnologies are likely to redefine the landscape of wireless communications.

Ajesh Kapoor, is country (India) manager, which designscommunications products.