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3G StandardsThe dream of 3G is to unify the world's mobile computing devices through a single, worldwide radio transmission standard. Imagine being able to go anywhere in the world secure in the knowledge that your mobile phone is compatible with the local system, a scenario known as "global roaming". Unfortunately, the process of unifying the numerous international standards has proved to be extremely difficult. After difficult negotiation, a 3G "standard" called IMT-2000 emerged as a rather unsatisfactory compromise. IMT-2000, in fact, represents several incompatible standards lumped together under one banner. The hope of IMT-2000 is that phones using these different standards will be able to move seamlessly between all networks, thus providing global roaming. The rather fragmented nature of IMT-2000 has resulted in a proliferation of confusion acronyms (e.g., TDMA, UMTS, EDGE) often referred to as "alphabet soup". Possibly the most important acronym to remember is "UMTS": this is the 3G standard for Europe and Japan. UMTS is the successor to the current ultra-successful GSM mobile phone standard in Europe. UMTS is being very heavily sold as the 3G standard (some sources use the terms "3G" and "UMTS" synonymously, though this is really not correct and just adds to the confusion). The main global competitor to UMTS is CDMA2000, the 3G standard developed in the U.S. by Qualcomm. UMTS and CDMA2000 look set to battle it out for global supremacy. However, other less-publicised standards will not let those two have it all their own way. It is hoped that the following guide will act as a roadmap through the confusing subject of 3G standards. Let's start by stepping back a "G"... 2G StandardsThe existing mobile phone market is referred to as the "second generation" of digital mobile communications, or "2G" (analogue mobile phones were "1G"). The European market is controlled by the Global System for Mobile communications (GSM) digital wireless standard. This uses TDMA as its radio transmission technology (RTT) (see the section on 3G Technology for a description of TDMA). GSM has proven to be the great success story of mobile standards as it has become the unifying standard in Europe - it is possible to use one phone throughout Western Europe. Because of the number of wireless users are in Europe this has greatly strengthened GSM's position as the basis for a potential global standard. The hegemony of GSM has resulted in Finland's Nokia and the UK's Vodafone becoming the powerhouses of the wireless economy. In North America the situation is not nearly so unified. The situation is divided three-ways between GSM, a TDMA-based system from AT&T Wireless (IS-136), and a CDMA system called CDMAone (IS-95A) from Sprint and Verizon. This confusion of standards has resulted in the reduced popularity of cellphones in the US. CDMAone has perhaps the strongest grip on the American market, as well as being popular in Asia. 
2G data transmission rates do not exceed 9.6Kbps (kilobits per second). This is not nearly fast enough to achieve complex 3G functionality. So let's move on ... 2.5G StandardsThe transition from 2G to 3G is technically extremely challenging (requiring the development of radically new transmission technologies), and highly expensive (requiring vast capital outlay on new infrastructure). For both of these reasons it makes sense to move to 3G via intermediate 2.5G standards. 2.5G radio transmission technology is radically different from 2G technology because it uses packet switching (see the section on 3G Technology for an explanation of packet switching). GPRS (General Packet Radio Service) is the European 2.5G standard, the upgrade from GSM. GPRS overlays a packet-switched architecture onto the GSM circuit-switched architecture. It is a useful evolutionary step on the road to 3G because it gives telecoms operators experience of operating packet networks, and charging for packet data. Data transfer rates will reach 50Kbps. EDGE (Enhanced Data for Global Evolution) is another 2.5G upgrade path from GSM. EDGE is attractive for American operators as it is possible to upgrade to EDGE from both TDMA (IS-136) networks as well as from GSM. You might see the full EGDE standard referred to as UWC-136. EDGE data rates are three times faster than GPRS. Realistically, the maximum rate that EDGE will be able to achieve will be 150Kbps. Even so, EDGE might be used for some pseudo-3G networks (the minimum cut-off data rate for 3G systems is 144Kbps) though this is not generally regarded as a bona fide 3G solution. As EDGE would be cheaper than a full-blown 3G solution, this makes it attractive, especially for operators which cannot afford a licence for the full 3G radio spectrum. Most notably, AT&T has announced it is to use EDGE. AT&T has claimed a maximum data rate of 384Kbps for EDGE, although experts point out that "this is based on the ideal scenario of one person using the network standing next to a base station"(!). AT&T's wireless division, after receiving a $9.8 billion stake from Japan's NTT DoCoMo i-mode service, plans to overlay the 3G standard, W-CDMA, onto their EDGE networks in the American market. Deploying EDGE might prove surprisingly complex - it's more than just a software upgrade. It may require additions to the hardware subsystems of base stations, changes to base station antennas, and possibly require the construction of new base stations. For these reasons, some GSM operators might not adopt EDGE but might migrate from GSM or GPRS directly to the 3G standard (W-CDMA, considered later). The 2.5G upgrade from CDMAone (IS-95A) is to CDMAone (IS-95B) which adds packet-switched capability. It offers data rates up to 115Kbps.  3G StandardsThe 3G standard was created by the International Telecommunication Union (ITU) and is called IMT-2000. The aim of IMT-2000 is to harmonize worldwide 3G systems to provide global roaming. However, as was explained in the introduction to this section, harmonizing so many different standards proved extremely difficult. As a result, what we have been left with is five different standards grouped together under the IMT-2000 label:
At this point, the definition of what is and what isn't "3G" becomes somewhat murky. Of these five standards, only three allow full network coverage over macro cells, micro cells and pico cells and can thus be considered as full 3G solutions: W-CDMA, CDMA2000, and TD-SCDMA. Of the remainder, DECT is used for those cordless phones you have in the house, and could be used for 3G short-range "hot-spots" (hence, it could be considered as being "part of a 3G network"), but it does not allow full network coverage so is not considered further here. And UWC-136 is another name for EDGE which is generally considered to be a 2.5G solution and was considered in the previous section. So that leaves W-CDMA, CDMA2000, and TD-SCDMA - the bona fide 3G solutions - which will now be covered in more detail:  Based on a presentation from the ITU. W-CDMA The 3G standard that has been agreed for Europe and Japan (very important markets) is known as UMTS. UMTS is an upgrade from GSM via GPRS or EDGE. UMTS is the European vision of 3G, and has been sold as the successor to the ultra-successful GSM. The terrestrial part of UMTS (i.e., non-satellite) is known as UTRA (UMTS Terrestrial Radio Access - don't you just love acronyms made from other acronyms!). The FDD component of UTRA is based on the W-CDMA standard (a.k.a. UTRA FDD). This offers very high (theoretical!) data rates up to 2Mbit/sec (the rumour is that the achievable rate is far lower: W-CDMA systems have been plagued with technical difficulties). The TDD component of UTRA is called TD-CDMA (or UTRA TDD) and will be considered later. The standardisation work for UMTS is being carried-out under the supervision of the Third Generation Partnership Project (3GPP). W-CDMA has recently been renamed 3GSM (to avoid confusion with CDMA2000). Cingular Video In the USA, Cingular has launched a UMTS service called Cingular Video. Cingular Video is the only service to offer Fox News clips in addition to news broadcasts from CNN and NBC. Cingular Video will initially be available in the markets of Atlanta, Austin, Baltimore, Boston, Chicago, Dallas, Houston, Las Vegas, New York, Phoenix, Portland, Salt Lake City, San Diego, San Francisco, San Jose, Seattle, Tacoma and Washington, D.C. with additional areas expanding rapidly. For more details, see the Cingular 3G demonstration here. FOMA NTT DoCoMo has gone live with 3G in Tokyo. Its service is called FOMA. This is the world's first IMT-2000 W-CDMA service (there are small but significant differences between the Japanese and European versions of W-CDMA - nothing is ever simple in 3G). Since the launch of the service, coverage has been extended to almost 100% of the Japanese population, and the release of new terminals with higher level functionality continues to attract ever more subscribers - now exceeding 20 million users. New phones in the FOMA lineup include the Sharp SH700i (shown below):  CDMA2000 The chief competitor to Europe's UMTS standard is San Diego-based Qualcomm's CDMA2000 (Qualcomm have done quite well out of CDMA - see here). The standardisation work for CDMA2000 is being carried-out under the supervision of the Third Generation Partnership Project 2, (3GPP2). The CDMA Development Group offers advice to 3GPP2. Even though "W-CDMA" and "CDMA2000" both have "CDMA" in their names, they are completely different systems using different technologies. However, it is hoped that mobile devices using the two systems will be able to talk to each other. CDMA2000 has two phases: phase one is 1XRTT (144 Kbps) (also known as 1X). The next evolutionary step is to the two CDMA2000 1X EV ("EV" = "Evolution") standards. CDMA2000 1X EV-DO ("Data Only") will use separate frequencies for data and voice. The following step is to CDMA2000 1X EV-DV ("Data and Voice") which will integrate voice and data on the same frequency band. South Korea's SK Telecom launched the world's first 3G system in October 2000. Their system is based on CDMA2000 1X. They were followed by LG Telecom and KT Freetel (both Korean). Operational 3G systems based on CDMA2000 1X are now appearing around the world. In the USA, Sprint has launched its nationwide CDMA2000 1X service called Sprint Power Vision. With Sprint PCS Vision Multimedia Services, customers get streaming audio and video content from familiar sources, including ABC News Now, NFL Network, Fox Sports, ESPN, NBC Discovery Channel, and many more. Sprint offer a range of multimedia phones including the Fusic:  Sprint is racing to catch up with Verizon's EV-DO rollout, and planned to have its EV-DO service live in 60 markets by spring 2006 (for the full article, see here). Also in the USA, Verizon has launched its high-speed 1X EV-DO service featuring three phones including the Chocolate (shown below). 
These phones are able to download content from the V CAST video service (see their great website). The on-demand clips offered currently are under four categories:
V CAST is now available to more than 140 million users across 171 cites in USA and is available in 68 primary airports. TD-CDMA/TD-SCDMA The UMTS standard also contains another radio transmission standard which is rarely mentioned: TD-CDMA (a.k.a. TDD UTRA because it is the TDD component of UTRA). TD-CDMA was developed by Siemens. While W-CDMA is an FDD technology (requiring paired spectrum), TD-CDMA is a TDD technology and thus can use unpaired spectrum (see the section on 3G Technology for an explanation of TDD and FDD). TDD is well-suited to the transmission of internet data (see the section on symmetric transmission vs. asymmetric transmission for an explanation). 
China has more mobile phone users than any other country in the world, so anything China does in 3G cannot be ignored. The Chinese national 3G standard is a TDD standard similar to TD-CDMA: TD-SCDMA. TD-SCDMA was developed by the China Academy of Telecommunications Technology (CATT) in collaboration with Siemens. TD-SCDMA eliminates the uplink/downlink interference which affects other TDD methods by applying "terminal synchonisation" techniques (the "S" in TD-SCDMA stands for "synchronisation"). Because of this, TD-SCDMA allows full network coverage over macro cells, micro cells, and pico cells. Hence, TD-SCDMA stands alongside W-CDMA and CDMA2000 as a fully-fledged 3G standard. The 3GPP have extended the TD-CDMA standard to include TD-SCDMA as an official IMT-2000 standard. Unfortunately, TD-SCDMA has performed poorly in trials, and Chinese network operators may prefer W-CDMA over TD-SCDMA.  Based on a presentation from the ITU. In many ways, it's almost TOO simple ... |
