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3G — Around the world and back again Where in the world is 3G? And who is doing what? By Raqibul Mostafa, Fakhrul Alam and Kyung Kyoon Bae
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he emergence of the 3G standard is a mandate to provide higher data rate and better spectrum efficiency. This standard is designed to overcome many of the key limitations imposed by existing 2G wireless systems. Web browsing, Internet-based applications and streaming audio/video represent some examples of present-day data communications that require high data rates. Seamless global roaming is also an attractive feature of 3G systems. In the process of providing enhanced voice/data services over wireless media, several competing 3G standards have been proposed and are vying for the honor of becoming the global 3G standard.
Figure 1. A road map of the wireless evolution (Courtesy ITU Web site).
The alphabet soup of 3G standards The 3GPP effort is based on the Global System for Mobile Communications (GSM) networks and is being carried out by a number of organizations, including the European Telecommunications Standards Institute (ETSI), the Association of Radio Industries and Businesses (ARIB), the 52
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Telecommunication Technology Committee (TTC), the Telecommunication Technology Association (TTA), and Committee T1 (Alliance for Telecommunications Industry Solutions). A parallel effort based on cdmaOne technology is being carried out under the umbrella of 3gPP2 by the Telecommunications Industrial of America (TIA), TTA, TTC, ARIB, and China Wireless Telecommunication Standards Group (CWTS). This effort is seen as eventually evolving into cdma2000 technology. There is one more effort to upgrade IS-136 system into UWC-136, but this is taking a backseat to the other 3G efforts. Wideband code-division multiple access (W-CDMA), from the Universal Mobile Telecommunications System (UMTS) and the ARIB, and cdma2000, from Qualcomm, are also considered key technologies for the upcoming global 3G standard. The 3GPP effort includes several versions of WCDMA (both frequency-division duplexing — FDD and time-division duplexing — TDD) and time-division synchronous CDMA (SCDMA). The evolution includes the intermediary 2.5G phases, general packet radio service (GPRS) and the enhanced data rates for GSM evolution (EDGE) standards. The cdma2000 evolution path involves 1xRTT and 1xEV phases. The 1xEV includes two migration phases; one is 1xEVDO and the other is 1xEVDV. Figure 1 shows a road map that depicts the evolution from the existing generations of wireless standards to the proposed 3G standards1. The standardization process has evolved through proposing and revising air-interface and network design parameters at different stages over the last several years. The actual deployment has been delayed due to technical difficulties that range from software/hardware development and legacy problems to spectrum allocation and local government policies. Some 3G standards are ready for field testing and initial small-scale deployment in some parts of the world. While the 3G standard is far from actual implementation and successful operation and harmonization across the globe, a new proposal is already emerging as the 4G standard. The wireless industry does not see clear technical aspects of the 4G standard because it needs to build on the experience of 3G for its evolution. The industry is still debating what 3G standard will be the predominant technology, and the state of flux regarding the perception about the promise and future of 3G technology adds to this confusion. We will present a review of the capabilities and the current status of existing 3G technologies. We will also provide findings on recent activities regarding the deployment from major 3G industry advocates. We will offer a clear picture of the present-day scenario for 3G and discuss the future for this standard.
Key aspects of 3G (W-CDMA) • Air-interface aspects The 3G standard aims to provide full coverage and mobility for 144 kb/s and 384kb/s, and limited coverage for 2 Mb/s. It also promises flexibility for new February 2002
Table 1. A comparative summary between the present-day dominant 2.5G standards.
services and more efficient spectrum use than existing systems. CDMA seems to be the multiple-access technique of choice for 3G systems. The nominal bandwidth is 5 MHz, and the chip rate is fixed at 3.84 Mchips/s. A user can enjoy several services with the appropriate quality of service. Users are separated by complex scrambling codes, whereas different services connected to a single user are separated by the orthogonal variable spreading factor (OVSF) codes. The physical layer supports the wireless link by means of different physical channels. A layered architecture supports data and voice flow within the devices (handset or base stations). Both synchronous and asynchronous network operations are supported. 3G systems offer many performance-enhancing features such as fast power control, transmit diversity and advanced space-time processing (2D Rake). A summary of air-interface parameters can be found in reference6. • Network aspects The upcoming 3G system is designed to provide existing 2G features and enhanced features such as quality of service (QoS) negotiation and provision, bandwidth on demand, multimedia mail store and forward, support of packet services, support of Internet, and satellite access. This requires efficient design and management of the network aspects of the 3G system. The network architecture of 3G UMTS is based on UMTS core network and UMTS terrestrial radio access network (UTRAN). The UMTS core is an Internet protocol- (IP) -based wired network that can be connected to either the IP backbone or a public switched telephone network (PSTN). Data transfer and routing between the Internet backbone, PSTN and mobile services switching center (MSC), and between the MSC and the base station, i.e., UTRAN can be supported by asynchronous transfer mode (ATM) protocol. The mobiles are connected to the network through either home location register (HLR), when they are in their own network, or visitor location register (VLR), when they are roaming. The HLR can be connected to the MSC through PSTN. The VLR is usually connected to the MSC. Usually, the service features offered to a mobile are implemented in software
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in the MSC. Additional new features require software upgrading by every MSC component manufacturer when the features reside in the MSC. To alleviate this, a wireless intelligent network (WIN) can host the feature software, allowing the features to execute in an intelligent network node2. The WIN will also host the HLR and service control point (SCP) functions. The WIN standards' Phase 1 capabilities include (as of 1999) incoming call screening (ICS), calling name presentation (CNAP), voice controlled services (VCS) and short-message services (SMS). The drivers that will shape the WIN standards may include Enhanced 911 (E-911), over-the-air service provisioning (OTASP) and 3G “virtual home environment.” The UTRAN provides wireless physical layers access between the mobile and the core. The UTRAN is a layered structure that operates on a protocol stack. The "stack" consists of the physical layer, the media access control (MAC), the radio link control (RLC), and the radio resource control (RRC) layers3. The 3G network is designed to support different services or quality of service (QoS). The QoS classes include conversational (speech, video telephony), streaming, interactive (Web browsing, telnet), and background (email, downloads); and they have priorities (based on delay requirement) according to the order in which they are presented. Providing QoS over-theair interface raises problems due to hand-offs and mobile IP addressing. The hand-off problem is taken care of by adaptive admission control, early resource reservation and a semi-reservation scheme. Employing mobile IP protocol accommodates the mobility of a handset terminal using the Internet. To maintain a connection that supports the different QoS levels, an enhanced form of the mobile RSVP protocol is used. The radio resources for 3G networks (transmission power, spreading code, etc.) are managed by dynamic resource scheduling (DRS)3.
Applications 3G technology holds potential for applications that require a high data rate. It is ironic, however, to find a lack of general consensus about potential
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drivers for this technology. Skeptics say that present-day voice quality and system capacity are satisfactory and that demand for an expensive, moderate data rate (the 2 Mb/s rate still not in the near future) services will not be prevalent. Existing wireless data services at a lower cost will tend to stall the deployment and growth of 3G systems. But key 3G proponents claim that the demand for mobile multimedia services and Internet applications will woo mobile subscribers in spite of the moderate initial expenses. According to Nokia5, the wireless services that will be offered by the service providers will include: • Location-based services (locationaware information, games and community services). • Mobile transactions (finance, trading, shopping). • Mobile information (news, financial, sports and traffic). • Wireless advertising. • Business solutions (e-mail, organizer, Web and wireless applications protocol {WAP} browsing, video conferencing). • Mobile entertainment (games, music, and video). One of the key applications for future wireless networks may come from “broker-solicited” online trading4. Jupiter Media Metrix analysts predict that “responsive” trades will be the premiere consumer brokerage application and will amount to about 13% of all online trades. This adds to the demand for a system that provides a high data rate with a guaranteed QoS.
Competing technologies One of the key contenders to 3G systems for high-data-rate services is the wireless local area networks (WLAN) system based on IEEE 802.11x standards. A recent article4 forecasts that WLAN devices will be widespread by 2006. It also stated that the number of WLAN hotspots will increase from 6,300 (2001) to 114,220, supporting about 17 million users worldwide and generating an annual revenue of $7.3 billion. The WLAN systems already support download speeds as high as 11 Mb/s, which is much faster than the 2 Mb/s rate envisioned in a 3G network. However, the major problem facing WLAN technology will be coverage. In January 2001, Japanese carrier NTT DoCoMo launched the latest version of its I-mode (Internet mode) service, known as I-
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appli (short for Internet applications), which supports next-generation Java phones and Java applications7. While Java phones cannot handle video or other high-bandwidth applications, they can support some animation, as well as agent technology, which is capable, for example, of retrieving stock quotes from Web sites and getting the information necessary to keep the stock charts on
the phone updated. Presently, I-appli users have access to games, online financial services and weather forecasts among other features. It has been a huge success in Japan, with more than 230,000 sold in the first week. In the United States , Bell South, Nextel, and Sprint PCS have all announced plans to roll out wireless services using next-genera-
tion Java technology 8. Telefonica of Spain and One-2-One in the UK, along with Far EasTone of Taiwan, SmarTone Telecommunications of Hong Kong, and J-Phone and KDDI of Japan, are expanding their services to take advantage of the increased functionality and ease of development offered by this same Java technology. Until the final data platform is decided upon, enhanced wireless functionality powered by Java technology is a simple and elegant answer to many of the present needs of subscribers.
3G ‘round the world — an overview The United States The deployment of 3G cellular systems faces two major obstacles: legacy problems arising from a multitude of already existing 2G networks and the availability (or lack thereof) RF spectrum. The existing networks are a major factor in determining what path the carriers will choose to get to 3G. Right now, W-CDMA and cdma2000 are the two realistic options. While W-CDMA is a natural progression of GSM technology, cdma2000 builds on standards currently using CDMA technology. The United States presently has six major carriers or wireless service providers (Verizon, Sprint, Cingular, AT&T Wireless, Nextel, VoiceStream) and between them they have three 2G cellular standards: CDMA, TDMA and GSM. This means that 3G in the United States may be heading toward both W-CDMA and cdma2000 as the platform for the next generation of mobile applications. Hoping to be the first to implement 3G in the United States, several of the major carriers have been conducting field trials on the cdma2000 1XRTT. It appears that although most of the carriers have not yet decided on a particular standard, they do have some interim plans to speed up networks while they decide which 3G wireless standard will eventually be pursued. Several of the U.S. carriers are stakeholders in European and Japanese carriers who have already adopted W-CDMA as their 3G standard. They wield a significant influence on their U.S. affiliates and may be the deciding factor in choice of a standard for the next-generation cellular network in the United States. Sprint PCS, whose network is solely CDMA-based, has decided to go with the cdma2000 standard. During the middle of March 2001, Sprint announced that it
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would roll out its 3G technology in four phases9. The first phase of the deployment will be to migrate to a cdma2000 network, which will double Sprint PCS’ network capacity for voice communications and increase data transmission speeds from 14.4 kb/s to 144 kb/s. In early 2003, Sprint PCS will move to the second stage in its 3G transition and offer data speeds of 307 kb/s. By late
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2003, data transmission speeds will reach 2.4 Mb/s, and in early 2004, transmission speeds for voice and data will hit between 3 Mb/s and 5 Mb/s. Companies supporting Sprint PCS’ 3G migration include Lucent Technologies, Motorola, Nortel Networks, and Qualcomm. AT&T Wireless, which has about 18% of the wireless market in the United States, is the only carrier in the United
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States to date that has officially stated that it will migrate to W-CDMA 10 . However, the company’s Japanese affiliate, NTT DoCoMo, which is a 16% stakeholder, likely had significant input in AT&T’s decision. AT&T Wireless’ plan is to begin overlaying GSM/GPRS on its TDMA network this year and is on schedule to begin introducing 2.5G services. The company will begin adding EDGE & UMTS in the 2002 to 2003 time frame to provide the higher data rates that will make “true” 3G services, such as streaming media using wireless devices, practical11. Nokia Networks will provide AT&T Wireless with GPRS-ready 850 and 1900 MHz radio network systems designed for seamless evolution to 3G. Verizon Wireless (which has a 27% share of the wireless market) is upgrading its network with interim technologies compatible with cdma200012. The carrier announced on Aug. 2, 2001 that it has upgraded its network to support next-generation technology for enhanced wireless voice capacity in parts of metro New York and northern New Jersey. Known as 1XRTT, this next-generation network infrastructure technology will significantly increase the voice capacity of Verizon Wireless’ digital wireless network once 1XRTT-compatible handsets become available. Lucent Technologies has a three-year, $5 billion deal with Verizon Wireless to supply 3G mobile telephony equipment. Verizon is also conducting trials with cdma2000- based Ericsson handsets. British worldwide carrier Vodafone, which owns about 45% of Verizon, has recently announced that it would encourage Verizon to switch to W-CDMA. As of now, it appears Verizon Wireless will eventually use a W-CDMA network standard for 3G wireless services13. VoiceStream, which is backed by the big European carrier Deutsche Telekom, will probably also be migrating toward W-CDMA. VoiceStream currently owns 6% market share in the United States. Given this scenario, W-CDMA appears to have won at least 51% of the U.S. market share. Cingular (with about 21% of the U.S. market share) probably faces the toughest road to 3G because its network is part TDMA and part GSM. In the middle of March 2002, the company announced it would roll out the 2.5G data service GPRS by mid-year14. The company plans to roll out service first in California, Nevada and Washington, followed by regions in the southeastern
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United States. Because GPRS is based on GSM networks, Cingular appears to be leaning toward W-CDMA. This overwhelming majority of W-CDMA may force Nextel (with a 9% market share) to also choose W-CDMA, though the company is currently conducting tests on cdma2000 1XRTT. Shortage of spectrum may seriously undermine 3G implementation in the
United States. The frequency band between 2.520 and 2.670 GHz has already been identified for 3G. However, this means that the six big carriers will have an average of somewhere between 25 MHz and 35 MHz of spectrum. In marked contrast, the big European carriers have about 90 MHz. As a result, many feel that the United States does not currently have adequate spectrum
for a full-fledged nationwide implementation of 3G mobile services. The FCC has been discussing the possible allocation of the 1.710 to 1.755 GHz band, primarily used by the U.S. Department of Defense, and the 2.110 to 2.150 GHz band, which is used by schools and health care centers15. Both the U.S. Army and the Navy have refused to move into another frequency band. They maintain that altering the frequency of the military’s equipment could be a security risk and this migration will not be a speedy process. The Air Force, however, has indicated that it would hand over its portion of the spectrum for $3.2 billion, which it claims is necessary for relocating its air-toground satellite communications system. Schools and health care centers have also balked at moving because of potentially enormous costs. As a result, the FCC is struggling to find suitable spectrum for 3G services and has recently postponed the designation of spectrum for 3G16. This could significantly delay the rollout of 3G in the United States.
Europe The deployment of 3G services in Europe seems to be significantly ahead of those in the United States. Because GSM was the prevalent 2G standard in Europe, the W-CDMA-based 3G standard was supported by the European carriers from the beginning. It appears that W-CDMA is being adopted as the nextgeneration standard throughout Europe. The spectrum for 3G has already been auctioned in different European countries, and the carriers have paid about $126 billion for wireless licenses17. The largest of European service providers, British-based Vodafone, had announced that commercial 3G services would be launched in the second half of 2002. However, recent developments suggest18 that it is slowing the rollout of its infrastructure for 3G networks, and its launch of 3G services could slip to 2003. In the UK, Vodafone now plans to build 750 base stations by the end of this year, instead of the original target of 1,200. Vodafone blamed the more cautious approach to introducing 3G services for the potential shortage of handsets for the next-generation mobile network. Vodafone said that despite what some manufacturers were indicating, development of dual-mode handsets that would support both existing GSM networks and 3G were being delayed. Ericsson has been selected as the principal supplier of infra-
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structure for the UK rollout of Vodafone’s new 3G network19. On April 16, 2001, Ericsson and Vodafone made the first call on a commercial W-CDMA network. Recently, British Telecommunications (BT) also indicated that it would delay the rollout of its first 3G service on Britain’s Isle of Man due to a software bug in equipment that made the cell-tocell handover of calls unreliable20. Nortel
and NEC have contracts with BT to supply 3G equipment20.
South America Most Latin American countries, except for the large countries like Brazil and Argentina, probably will not roll out 3G services anytime soon. The Brazilian administration is currently reviewing the opportunities to issue personal com-
munications system (PCS) licenses. Telesp Celular, Brazil's largest mobile operator, and Lucent recently announced a $130 million contract to introduce the first 3G mobile network in Brazil21. They are going with the interim cdma2000-based 1XRTT. On the other hand, Telemar, the biggest fixed operator in Brazil, is planning on launching a GSM-based GPRS service with help from Nokia. The network will be operational at the beginning of 200222. This is a strong indication that W-CDMA could be the next-generation technology chosen by the company. Argentina is in the process of auctioning the spectrum for 3G, and the Argentine government expects to raise between $500 million and $600 million from auctions. Current 2G services in Argentina include CDMA, GSM and TDMA [23]. As a result, the country could be heading toward both W-CDMA and cdma2000.
Asia • Korea The deployments of 3G wireless networks have been delayed in Korea. Some critics are casting doubts about deploying 3G wireless networks due to existing 2G networks and the cost of deploying 3G. Even though some skepticism exists, 3G is moving forward, although slowly. Korea is the first country in the world to successfully deploy CDMA-based systems nationwide. It developed CDMA network equipment in cooperation with Qualcomm, which originally proposed and developed CDMA technology for commercial use. Hence, all of the 2G cellular systems in Korea are based on IS95 CDMA technology. As a result, it seems that the selection of cdma2000 is a natural migration from 2G to 3G. However, all of the major service providers in Korea insisted on deployment of 3G systems based on W-CDMA because they wanted global roaming throughout Asia where most of the 2G networks are GSM-based. Meanwhile, the Korean government wanted to keep both W-CDMA and cdma2000 as standards for 3G. The Korean government has selected two service providers, SK IMT and KT ICOM, as W-CDMA-based service providers and one consortium consisting of LG Telecom, Hanaro, and PowerComm as cdma2000-based service providers 24 . As the competition for attracting more subscribers to faster
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wireless Internet access begins to intensify, three major wireless service providers, SK Telecom, KT, and LG Telecom, are now providing CDMA 1x based services and getting ready for the cdma2000 1X-EV-DO. The biggest service carrier, SK Telecom, which has about 50% of the wireless market in Korea, is the first in the world to offer 3G services to its customers and provides the highest data rate at 144 kb/s, based on Qualcomm's cdma2000 technology25. SK Telecom is even planning on expanding services nationwide 26. SK IMT, which merged with SK Telecom, announced in June 2001 that the company would not deploy its W-CDMA IMT-2000 3G wireless service as it had originally promised. Also, the company plans to launch commercial service of a CDMA-IMT 2000 service as a 3G cdma2000 1X-EV-DO (evolution data only) before June 200227,28. Hence, the deployment by SK Telecom for W-CDMAbased wireless services will see at least a one-year delay from its original launch date. KT ICOM, the second largest wireless carrier in Korea, is in the selection process for infrastructure equipment suppliers to place orders for W-CDMA-based wireless network equipment. The company is planning to deploy its W-CDMAbased wireless services in the fourth quarter of 200229. However, skepticism exists about deploying W-CDMA-based wireless networks. Qualcomm disclosed that the company would not be able to make the core chipsets to support roaming between 2G and 3G, and between cdma2000 and WCDMA-based networks, to the public until 200330. Because the Korean government requires service providers to support roaming between heterogeneous networks such as 2G and 3G, and cdma200based and W-CDMA-based networks, and even requires dual-mode handset, the nationwide deployment of 3G wireless services is expected to be delayed. • Japan The deployment of 3G W-CDMAbased services in Japan is significantly ahead of that in the United States and is competing with European companies. Two wireless carriers acquired a license for W-CDMA-based 3G services, and one carrier acquired a license for cdma2000based 3G services. NTT DoCoMo conducted trial WCDMA-based 3G services called “freedom of multimedia access” (FOMA) to 4,500 subscribers in Tokyo, Kawasaki,
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and Yokohama on May 30, 200131. The trial service was conducted for four months with the expected maximum data rate of 384 kb/s. NTT DoCoMo is planning on nationwide services in 2003. J-Phone Communications, Japan's third-largest mobile phone provider and a subsidiary of Japan Telecom, announced that it would postpone services until October 2002. J-Phone said it needs more time to adopt the new 3G standards. Industry analysts anticipated that J-Phone would become the single rival to NTT DoCoMo, as J-Phone had earlier said that it would complete commercialization procedures by the end of the year 200132. • China Most of the current 2G networks in China are GSM-based. China Mobile, China's largest mobile service provider, uses GSM technology. China Unicom, China's sole CDMA service provider and the second largest, is making headway in offering cdma2000 service aimed at 78 million subscribers, which accounts for a market share of 30%, over the next five years33. The company made contracts for CDMA mobile equipment with Lucent Technologies and Motorola for $400 million each, with Nortel Networks for $275 million, and with Samsung and Ericsson for $200 million each35. • India India plans to use cdma2000 technology as the 3G standard. • Australia Hutchison Telecom made a contract with Ericsson for a 3G network in Australia for $435 million (AUD 830 million), marking Ericsson's first 3G project in Australia and its 32nd contract for wideband-CDMA deployment. Ericsson will provide a radio access network, IP core network and transmission technologies. Also included in the contract are advanced network management systems, network operations, mobile Internet application platforms and terminals35.
Conclusions After a review of the recent activities regarding 3G technology, it is obvious that widespread 3G activities are happening around the globe. However, clouds loom on the horizon. Factors such as slow growth, delayed deployment, and technical and financial hurdles casts shadows on deployment times and pervasiveness. Furthermore, the emergence of new wireless data services may pose a great
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threat to the nascent 3G technology by being strong contenders for high-datarate services. Another prevalent view among the wireless community is the lack of “killer applications” to corroborate the need for migration to a new system. There is a need to see how people respond to current changes and whether they are ready to pay more for enhanced services. However, even with all these thorny issues, 3G is making a slow but steady progress toward positioning itself as the global voice and high-data-rate service of the future.
References Because the reference list for this article is so extensive, please refer to our Web site: www.rfdesign.com.
About the authors Raqibul Mostafa received his B.S. degree in electrical and electronics engineering in 1991 from Bangladesh University of Engineering and Technology. He obtained his M.S. degree in electrical engineering from Virginia Tech in 1995. He joined MPRG for his doctoral program in January 1997. He is doing research with Dr. Jeffrey H. Reed in antenna array algorithms and applications. Fakhrul Alam received his B.S. degree in electrical and electronic engineering from Bangladesh University of Engineering and Technology (BUET). He started in the M.S. program at Virginia Tech from the fall of 1997 and joined MPRG in the fall of 1998. He completed his M.S. program in December 1999. He is continuing as a Ph.D. student with Dr. Brian D. Woerner working on space-time processing for third-generation (3G) systems. Kyung Kyoon Bae (
[email protected]) received a B.S. degree in electrical engineering from Yonsei University in Republic of Korea in 1993, and M.S. degree in electrical and computer engineering from Virginia Tech in 1998. Since 1999 he is pursuing a Ph.D. degree with Virginia Tech’s mobile and portable radio research group (MPRG). The authors would like to extend a special thanks to their professors, Jeffrey H. Reed, Brian D. Woerner and William H. Tranter. An abridged version originally appeared in the Spring/summer 2001 issue of the MPRG Propagator.
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