Universal Mobile Telecommunications System

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Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) cell phone technologies, which is also being developed into a 4G technology. Currently, the most common form of UMTS uses W-CDMA as the underlying air interface. It is standardized by the 3GPP, and is the European answer to the ITU IMT-2000 requirements for 3G cellular radio systems.
To differentiate UMTS from competing network technologies, UMTS is sometimes marketed as 3GSM, emphasizing the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed.
Preface
This article discusses the technology, business, usage and other aspects encompassing and surrounding UMTS, the 3G successor to GSM which utilizes the W-CDMA air interface and GSM infrastructures. Any issues relating strictly to the W-CDMA interface itself may be better described in the W-CDMA page.
Features
UMTS, using W-CDMA, supports up to 14.0 Mbit/s data transfer rates in theory (with HSDPA), although at the moment users in deployed networks can expect a transfer rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the downlink connection. This is still much greater than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel or multiple 9.6 kbit/s channels in HSCSD (14.4 kbit/s for CDMAOne), and—in competition to other network technologies such as CDMA2000, PHS or WLAN—offers access to the World Wide Web and other data services on mobile devices.
Precursors to 3G are 2G mobile telephony systems, such as GSM, IS-95, PDC, PHS and other 2G technologies deployed in different countries. In the case of GSM, there is an evolution path from 2G, to GPRS, also known as 2.5G. GPRS supports a much better data rate (up to a theoretical maximum of 140.8 kbit/s, though typical rates are closer to 56 kbit/s) and is packet switched rather than connection orientated (circuit switched). It is deployed in many places where GSM is used. E-GPRS, or EDGE, is a further evolution of GPRS and is based on more modern coding schemes. With EDGE the actual packet data rates can reach around 180 kbit/s (effective). EDGE systems are often referred as "2.75G Systems".
Since 2006, UMTS networks in many countries have been or are in the process of being upgraded with High Speed Downlink Packet Access (HSDPA), sometimes known as 3.5G. Currently, HSDPA enables downlink transfer speeds of up to 7.2 Mbit/s. Work is also progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access (HSUPA). Longer term, the 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation air interface technology based upon OFDM.
UMTS supports mobile videoconferencing, although experience in Japan and elsewhere has shown that user demand for video calls is not very high.
Other possible uses for UMTS include the downloading of music and video content, as well as live TV.
Deployment
See also: List of Deployed UMTS networks
Technology
UMTS combines the W-CDMA, TD-CDMA, or TD-SCDMA air interfaces, GSM's Mobile Application Part (MAP) core, and the GSM family of speech codecs. In the most popular cellular mobile telephone variant of UMTS, W-CDMA is currently used. Note that other wireless standards use W-CDMA as their air interface, including FOMA.
UMTS over W-CDMA uses a pair of 5 MHz channels. In contrast, the competing CDMA2000 system uses one or more arbitrary 1.25 MHz channels for each direction of communication. UMTS and other W-CDMA systems are widely criticized for their large spectrum usage, which has delayed deployment in countries that acted relatively slowly in allocating new frequencies specifically for 3G services (such as the United States).
The specific frequency bands originally defined by the UMTS standard are 1885–2025 MHz for the mobile-to-base (uplink) and 2110–2200 MHz for the base-to-mobile (downlink). In the US, 1710–1755 MHz and 2110–2155 MHz will be used instead, as the 1900 MHz band was already utilized.[1] Additionally, in some countries UMTS operators use the 850 MHz and/or 1900 MHz bands (independently, meaning uplink and downlink are within the same band), notably in the US by AT&T Mobility, and in Australia by Telstra (850 MHz only). A UMTS900 network has also opened in Finland, planned for more rural areas and other hard coverage areas over the GSM shared 900 MHz spectrum, supported currently by Elisa and Nokia (by model 6121 classic) and also encouraged by the local regulators.
For existing GSM operators, it is a simple but costly migration path to UMTS: much of the infrastructure is shared with GSM, but the cost of obtaining new spectrum licenses and overlaying UMTS at existing towers can be prohibitively expensive.
A major difference of UMTS compared to GSM is the air interface forming GSM/EDGE Radio Access Network (GeRAN). It can be connected to various backbone networks like the Internet, ISDN, GSM or to a UMTS network. GeRAN includes the three lowest layers of OSI model. The network layer (OSI 3) protocols form the Radio Resource Management protocol (RRM). They manage the bearer channels between the mobile terminals and the fixed network including the handovers.
Releases
The evolution of the system will move forward with so called releases. Each release will introduce new features. The following features are examples of many others in these new releases.
Release '99
• Bearer services
• 64 kbit/s circuit switched
• 384 kbit/s packet switched
• Location services
• Call services: compatible with Global System for Mobile Communications (GSM), based on Universal Subscriber Identity Module (USIM)
Release 4
• Edge radio
• Multimedia messaging
• MExE (Mobile Execution Environment)
• Improved location services
• IP Multimedia Services (IMS)
Release 5
• IP Multimedia Subsystem (IMS)
• IPv6, IP transport in UTRAN
• Improvements in GERAN, MExE, etc
• HSDPA
Release 6
• WLAN integration
• Multimedia broadcast and multicast
• Improvements in IMS
• HSUPA

3G Handsets and Modems
All of the major 2G phone manufacturers are now developers of 3G phones. The early 3G handsets and modems were specific to the frequencies required in their country, which meant they could only roam to other countries on the same 3G frequency (though they can fall back to the older GSM standard). Canada and USA have a common share of frequencies, as do most European countries. Look at UMTS frequency bands to see the similarities between each country's network frequency. Canada phones could be used in BAND II and/or V as an example.
There are almost no 3G phones/modems available supporting all 3G frequencies (850/900/1700/1900/2100, UMTS, not GSM). Some modems like the Huawei E270 meet this specification [2], however many phones are offering more than one band which still enables extensive roaming. For example, a tri-band chipset with 850/1900/2100 allows usage in most countries.
Phones
Newer phone models have 3G built-in but are usually designed for a specific provider's network as per UMTS frequency bands. These phones may be used for the Internet directly on the phone or, via tether mode, can be attached via Wifi, Bluetooth, Infrared or USB to a computer to access the Internet. [3]
PDA and Smartphones
• Symbian Based: with 65% of the market. Nokia and Sony Ericsson are the major SymbianOS users. There is a lot of SymbianOS software available but often only applicable to specific phones. Tethering is available using USB, bluetooth or Wifi (with JoikuSpot: Convert your Symbian Phone into a router).[4]
• Windows Mobile Based: with 12% of the current market. Windows Mobile 6.1 offers a range of features for UMTS. Tethering is available using USB, bluetooth, or Wifi (with WMWifiRouter: convert your Windows Mobile unit into a router)[5] Windows Mobile is used by many manufacturers including Sony, Samsung, Palm, Motorola, and several manufacturers familiar with the PC market.
• RIM OS Based: with 11% of the market. Most BlackBerry smartphones are not currently 3G capable, with the exception of certain models such as model 8707v, EVDO capable models and the upcoming BlackBerry 9000 series. One reason is that BlackBerry, typically known for long battery life, would have shorter battery life with 3G. The emergence of greatly improved multimedia and tethering capabilities on recent BlackBerry models, is currently pressuring RIM to include 3G in future BlackBerry models.
• Mac OS X-like iPhone OS Based: with 7% of the market. Apple's first generation iPhone did not support 3G and is restricted to using the EDGE standard. Apple claimed this was to maintain a reasonable battery life on the telephone. Power usage of 3G is improving, and Apple released a 3G/UMTS iPhone on July 11, 2008.
• Palm OS (also known as "Garnet OS") was initially developed by Palm Computing, Inc. for personal digital assistants (PDAs) in 1996 and was later also used on some mobile phones. It is provided with a suite of basic applications for personal information management. Palm OS has been used in Sony Clié handsets (Sony now uses Windows Mobile & Symbian) and by Samsung (which now use Windows Mobile).
• Android is a software platform and operating system for mobile devices based on the Linux operating system and developed by Google and the Open Handset Alliance.[6] It allows developers to write managed code in a Java-like language that utilizes Google-developed Java libraries,[7] but does not support programs developed in native code. When released in 2008, most of the Android platform will be made available under the Apache free-software and open-source license.[8]
External Modems
Using a cellular router, PCMCIA or USB card, customers are able to access 3G broadband services, regardless of their choice of computer (such as a tablet PC or a PDA). Some software installs itself from the modem, so that in some cases absolutely no knowledge of technology is required to get online in moments.
Using a phone that supports 3G and Bluetooth 2.0, multiple Bluetooth-capable laptops can be connected to the Internet. The phone acts as a router, but via Bluetooth rather than wireless networking (802.11) or a USB connection.
Interoperability and global roaming
UMTS phones (and data cards) are highly portable—they have been designed to roam easily onto other UMTS networks (assuming your provider has a roaming agreement). In addition, almost all UMTS phones (except in Japan) are UMTS/GSM dual-mode devices, so if a UMTS phone travels outside of UMTS coverage during a call the call may be transparently handed off to available GSM coverage. Roaming charges are usually significantly higher than regular usage charges.
Most UMTS licensees consider ubiquitous, transparent global roaming an important issue. To enable a high degree of interoperability, UMTS phones usually support several different frequencies in addition to their GSM fallback. Different countries support different UMTS frequency bands – Europe initially used 2100 MHz while the USA used 1700 MHz, and a UMTS phone and network must support a common frequency to work together. Because of the frequencies used, early models of UMTS phones designated for the US will likely not be operable elsewhere and vice versa. There are now 11 different frequency combinations used around the world—including frequencies formerly used solely for 2G services.
UMTS phones use a USIM (Universal Subscriber Identity Module) (based on GSM's SIM) and also accept GSM SIM cards. This is a global standard of identification, and enables a network to identify the phone user to authenticate both local and roaming customers. Roaming agreements between networks allow for calls to a customer to be redirected to them while roaming and determine the services (and prices) available to the user. In addition to user subscriber information and authentication information, the USIM provides storage space for phone book contacts—phones can store their data on their own memory or on the USIM card (which is usually more limited in its phone book contact information). A USIM can be moved to another UMTS or GSM phone, and the phone will take on the user details of the USIM—meaning it is the USIM (not the phone) which determines the phone number of the phone and the billing for calls made from the phone.
Japan was the first country to adopt 3G technologies, and since they had not used GSM previously they had no need to build GSM compatibility into their handsets and their 3G handsets were smaller than those available elsewhere. In 2002, NTT DoCoMo's FOMA 3G network was the first commercial W-CDMA network—it was initially incompatible with the UMTS standard at the radio level but used standard USIM cards, meaning USIM card based roaming was possible (moving the USIM card into a UMTS or GSM phone when travelling). Both NTT and SoftBank Mobile (which launched 3G in December 2002) now use the standard UMTS, and their PDC 2G networks run in parallel.
Spectrum allocation
Main article: UMTS frequency bands
Over 120 licenses have already been awarded to operators worldwide (as of December 2004), specifying W-CDMA radio access technology that builds on GSM. In Europe, the license process occurred at the end of the technology bubble, and the auction mechanisms for allocation set up in some countries resulted in some extremely high prices being paid for the original 2100 MHz licenses, notably in the UK and Germany. In Germany, bidders paid a total 50.8 billion euros for six licenses, two of which were subsequently abandoned and written off by their purchasers (Mobilcom and the Sonera/Telefonica consortium). It has been suggested that these huge license fees have the character of a very large tax paid on income expected 10 years down the road—in any event they put some European telecom operators close to bankruptcy (most notably KPN). Over the last few years some operators have written off some or all of the license costs. More recently, a carrier in Finland has begun using 900 MHz UMTS in a shared arrangement with its surrounding 2G GSM base stations, a trend that is expected to expand over Europe in the next 1–3 years.
The 2100 MHz UMTS spectrum allocated in Europe is already used in North America. The 1900 MHz range is used for 2G (PCS) services, and 2100 MHz range is used for satellite communications. Regulators have, however, freed up some of the 2100 MHz range for 3G services, together with the 1700 MHz for the uplink. UMTS operators in North America who want to implement a European style 2100/1900 MHz system will have to share spectrum with existing 2G services in the 1900 MHz band.
AT&T Wireless launched UMTS services in the United States by the end of 2004 strictly using the existing 1900 MHz spectrum allocated for 2G PCS services. Cingular acquired AT&T Wireless in 2004 and has since then launched UMTS in select US cities. After AT&T's acquisition of Cingular, it was renamed AT&T Mobility and is rolling out some cities with a UMTS network at 850 MHz to enhance its existing UMTS network at 1900 MHz and now offers subscribers a number of UMTS 850/1900 phones.
T-Mobile's roll-out of UMTS in the US will focus on the 2100/1700 MHz bands just auctioned.
Initial rollout of UMTS in Canada will also be undertaken using the 850 and 1900 MHz bands due to the large areas that will be needed to cover.
In Australia, Telstra rolled out a national 3G network, branded as NextG, operating in the 850 MHz band to replace the existing CDMA network (April 2008) and enhance its existing 2100 MHz UMTS network. Optus is currently rolling out a 3G network with the same coverage as its GSM network, using the 2100 MHz band in cities and most large towns, and the 900 MHz band for regional areas. Vodafone is also building a 3G network using the 900 MHz band. The 850 MHz and 900 MHz bands provide greater coverage compared to equivalent 1700/1900/2100 MHz networks, and are best suited to regional areas where greater distances separate subscriber and base station.
Carriers in South America are now also rolling out 850 MHz networks.
Other competing standards
There are other competing 3G standards, such as CDMA2000 and TD-SCDMA, though UMTS can use the latter's air interface standard.
On the Internet access side, competing systems include WiMAX and Flash-OFDM. Different variants of UMTS compete with different standards. While this article has largely discussed UMTS-FDD, a form oriented for use in conventional cellular-type spectrum, UMTS-TDD, a system based upon a TD-CDMA air interface, is used to provide UMTS service where the uplink and downlink share the same spectrum, and is very efficient at providing asymmetric access. It provides more direct competition with WiMAX and similar Internet-access oriented systems than conventional UMTS.
Both the CDMA2000 and W-CDMA air interface systems are accepted by ITU as part of the IMT-2000 family of 3G standards, in addition to UMTS-TDD's TD-CDMA, Enhanced Data Rates for GSM Evolution (EDGE) and China's own 3G standard, TD-SCDMA.
CDMA2000's narrower bandwidth requirements make it easier than UMTS to deploy in existing spectrum along with legacy standards. In some, but not all, cases, existing GSM operators only have enough spectrum to implement either UMTS or GSM, not both. For example, in the US D, E, and F PCS spectrum blocks, the amount of spectrum available is 5 MHz in each direction. A standard UMTS system would saturate that spectrum.
In many markets however, the co-existence issue is of little relevance, as legislative hurdles exist to co-deploying two standards in the same licensed slice of spectrum.
Most GSM operators in North America as well as others around the world have accepted EDGE as a temporary 3G solution. AT&T Wireless launched EDGE nationwide in 2003, AT&T launched EDGE in most markets and T-Mobile USA has launched EDGE nationwide as of October 2005. Rogers Wireless launched nation-wide EDGE service in late 2003 for the Canadian market. Bitė Lietuva (Lithuania) was one of the first operators in Europe to launch EDGE in December 2003. TIM (Italy) launched EDGE in 2004. The benefit of EDGE is that it leverages existing GSM spectrums and is compatible with existing GSM handsets. It is also much easier, quicker, and considerably cheaper for wireless carriers to "bolt-on" EDGE functionality by upgrading their existing GSM transmission hardware to support EDGE than having to install almost all brand-new equipment to deliver UMTS. EDGE provides a short-term upgrade path for GSM operators and directly competes with CDMA2000.
Problems and issues
Some countries, including the United States and Japan, have allocated spectrum differently from the ITU recommendations, so that the standard bands most commonly used for UMTS (UMTS-2100) have not been available. In those countries, alternative bands are used, preventing the interoperability of existing UMTS-2100 equipment, and requiring the design and manufacture of different equipment for the use in these markets. As is the case with GSM-900 today, standard UMTS 2100 MHz equipment will not work in those markets. However, it appears as though UMTS is not suffering as much from handset band compatibility issues as GSM did, as many UMTS handsets are multi-band in both UMTS and GSM modes. Quad-band GSM (850, 900, 1800, and 1900 MHz bands) and tri-band UMTS (850, 1900, and 2100 MHz bands) handsets are becoming more commonplace.
In the early days of UMTS there were issues with rollout:
• overweight handsets with poor battery life;
• problems with handover from UMTS to GSM, connections being dropped or handovers only possible in one direction (UMTS → GSM) with the handset only changing back to UMTS after hanging up, even if UMTS coverage returns—in most networks around the world this is no longer an issue;
• for fully fledged UMTS incorporating video on demand features, one base station needed to be set up every 1–1.5 km (0.62–0.93 mi). This was the case when only the 2100 MHz band was being used, however with the growing use of lower-frequency bands (such as 850 and 900 MHz) this is no longer so. This has led to an increase in the interest in the lower-band networks by operators since 2006.
Some of these issues may still be ongoing; for instance, Apple, Inc. cited[9] UMTS power consumption as the reason that the first generation iPhone only supported EDGE. Their release of the iPhone 3G quotes talk time in 3G mode as half that of the 2G mode.
Other, non-UMTS, 3G and 4G standards:
• CDMA2000: evolved from the cmdaOne (also known as IS-95, or "CDMA") standard, managed by the 3GPP2
• FOMA
• TD-SCDMA
• WiMAX: a newly emerging wide area wireless technology.
UMTS is an evolution of the GSM mobile phone standard.
• GSM
• GPRS
• EDGE
• ETSI
Other useful information
• Mobile modem
• Spectral efficiency comparison table
• Code Division Multiple Access (CDMA)
• Common pilot channel or CPICH, a simple synchronisation channel in WCDMA.
• Multiple-input multiple-output (MIMO) is the major issue of multiple antenna research.
• Wi-Fi: a local area wireless technology that is complementary to UMTS.
• Mobile Internet access worldwide lists mobile (mainly UMTS/HSDPA) Internet access solutions worldwide.
• List of device bandwidths
Literature
• Martin Sauter: Communication Systems for the Mobile Information Society, John Wiley, September 2006, ISBN 0-470-02676-6
References
1. ^ The FCC's Advanced Wireless Services bandplan
2. ^ "Huawei E270 GSM/UMTS modem specifications". Retrieved on 2008-06-08.
3. ^ ^ For an example of tether mode, http://thenokiablog.com/2007/08/21/how-to-tether-your-nokia-to-a-mac-to-access-the-net-via-bluetooth/
4. ^ ^ http://network.nationalpost.com/np/blogs/tradingdesk/archive/2008/04/30/what-to-expect-from-rogers-iphone-offering.aspx
5. ^ ^ http://www.canalys.com/pr/2008/r2008021.htm.
6. ^ "Industry Leaders Announce Open Platform for Mobile Devices" (HTML) (in English). Open Handset Alliance (2007-11-05). Retrieved on 2007-11-05.
7. ^ "Google's Android parts ways with Java industry group".
8. ^ "Open Handset Alliance Releases Android SDK" (HTML) (in English). Open Handset Alliance (2007-11-12). Retrieved on 2007-11-12.
9. ^ ^http://online.wsj.com/article/SB118306134626851922.html
External links
• GSM/UMTS market statistics from the 'Global mobile suppliers association'
• 3GPP Specifications Numbering Scheme
• 3GPP document listing all UMTS Technical Standards for Release 6 and earlier
• Vocabulary for 3GPP Specifications, up to Release 8
• UMTS FAQ on UMTS World d
• Worldwide W-CDMA frequency allocations on UMTS World
• UMTS TDD Alliance The Global UMTS TDD Alliance
• 3GToday.com
• 3GSM World Congress
source: http://en.wikipedia.org/wiki/Universal_Mobile_Telecommunications_System