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{{Short description|Third generation mobile cellular system}}
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{{lead too short|date=December 2016}}
{{more citations needed|date=December 2016}}
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The '''Universal Mobile Telecommunications System''' ('''UMTS''') is a [[3G|third generation]] mobile cellular system for networks based on the [[GSM]] standard. Developed and maintained by the [[3GPP]] (3rd Generation Partnership Project), UMTS is a component of the [[International Telecommunication Union]] [[IMT-2000]] standard set and compares with the [[CDMA2000]] standard set for networks based on the competing [[IS-95|cdmaOne]] technology. UMTS uses wideband [[code-division multiple access]] ([[W-CDMA]]) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.
 
UMTS specifies a complete network system, which includes the [[radio access network]] ([[UMTS Terrestrial Radio Access Network]], or UTRAN), the [[core network]] ([[Mobile Application Part]], or MAP) and the authentication of users via SIM ([[subscriber identity module]]) cards.
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== Features ==
UMTS supports maximum theoretical maximum data [[Bit rate|transfer rates]] of 42&nbsp;[[Mbit/s]] when [[Evolved HSPA]] (HSPA+) is implemented in the network.<ref>{{cite web | url=httphttps://www.zdnet.com.au/newshome-and-office/communicationsnetworking/soa/Telstratelstra-boosts-Nextnext-Gg-to-21Mbps21mbps/0,130061791,339293706,00.htm | title=Telstra boosts Next G to 21Mbps | first=Suzanne | last=Tindal | date=8 December 2008 | publisher=[[ZDNet]] Australia | access-date=2009-03-16}}</ref> Users in deployed networks can expect a transfer rate of up to 384&nbsp;kbit/s for Release '99 (R99) handsets (the original UMTS release), and 7.2&nbsp;Mbit/s for [[High-Speed Downlink Packet Access]] (HSDPA) handsets in the downlink connection. These speeds are significantly faster than the 9.6&nbsp;kbit/s of a single GSM error-corrected circuit switched data channel, multiple 9.6&nbsp;kbit/s channels in [[High-Speed Circuit-Switched Data]] (HSCSD) and 14.4&nbsp;kbit/s for CDMAOne channels.
 
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 21&nbsp;Mbit/s. Work is also progressing on improving the uplink transfer speed with the [[High-Speed Uplink Packet Access]] (HSUPA). LongerThe term, the3GPP [[3GPPLTE Long Term Evolution(telecommunication)|LTE]] (LTE)standard projectsucceeds plansUMTS toand moveinitially UMTS toprovided 4G speeds of 100&nbsp;Mbit/s down and 50&nbsp;Mbit/s up, with scalability up to 3&nbsp;Gbps, using a next generation air interface technology based upon [[OFDM|orthogonal frequency-division multiplexing]].
 
The first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and [[Video teleconference|video calling]]. The high data speeds of UMTS are now most often utilised for Internet access: experience in Japan and elsewhere has shown that user demand for video calls is not high, and telco-provided audio/video content has declined in popularity in favour of high-speed access to the World Wide Web{{snd}} either directly on a handset or connected to a computer via [[Wi-Fi]], [[Bluetooth]] or [[USB]].{{Citation needed|reason=Reliable source needed for the whole sentence|date=April 2015}}
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UMTS combines three different terrestrial [[air interface]]s, [[Global System for Mobile Communications|GSM]]'s [[Mobile Application Part]] (MAP) core, and the GSM family of [[speech codec]]s.
 
The air interfaces are called UMTS Terrestrial Radio Access (UTRA).<ref name="glossary01">{{cite web |url=http://www.3gnewsroom.com/html/glossary/u.shtml |title=3G Glossary{{Snd}} UTRA | website=3GNewsroom.com |date=2003-11-29 |archive-url=https://web.archive.org/web/20110406074310/http://www.3gnewsroom.com/html/glossary/u.shtml |archive-date=2011-04-06}}</ref> All air interface options are part of [[ITU]]'s [[IMT-2000]]. In the currently most popular variant for cellular mobile telephones, W-CDMA (IMT Direct Spread) is used. It is also called "Uu interface", as it links User Equipment to the UMTS Terrestrial Radio Access Network.
 
Please note that the terms [[W-CDMA]], [[TD-CDMA]] and [[TD-SCDMA]] are misleading. While they suggest covering just a [[channel access method]] (namely a variant of [[CDMA]]), they are actually the common names for the whole air interface standards.<ref name="ituover">{{cite web|url=http://www.itu.int/dms_pub/itu-d/opb/stg/D-STG-SG02.18-1-2006-PDF-E.pdf|author=ITU-D Study Group 2|title=Guidelines on the smooth transition of existing mobile networks to IMT-2000 for developing countries (GST); Report on Question 18/2|access-date=2009-06-15|pages=4, 25–28}}</ref>
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[[File:UMTS-fridge.jpg|thumb|UMTS base station on the roof of a building]]
 
[[W-CDMA]] (WCDMA; Wideband [[Code-Division Multiple Access]]), along with UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in [[3G]] [[mobile telecommunications]] networks. It supports conventional cellular voice, text and [[Multimedia Messaging Service|MMS]] services, but can also carry data at high speeds, allowing mobile operators to deliver higher bandwidth applications including streaming and broadband Internet access.<ref>{{cite web|url=http://www.gsma.com/aboutus/gsm-technology/3gwcdma |title=What is 3G/WCDMA? |publisher=GSMA.com |access-date=2014-06-24}}</ref>
 
W-CDMA uses the [[DS-CDMA]] channel access method with a pair of 5&nbsp;MHz wide channels. In contrast, the competing [[CDMA2000]] system uses one or more available 1.25&nbsp;MHz channels for each direction of communication. W-CDMA systems are widely criticized for their large spectrum usage, which delayed deployment in countries that acted relatively slowly in allocating new frequencies specifically for 3G services (such as the United States).
 
The specific [[Band (radio)|frequency bands]] originally defined by the UMTS standard are 1885–2025&nbsp;MHz for the mobile-to-base (uplink) and 2110–2200&nbsp;MHz for the base-to-mobile (downlink). In the US, 1710–1755&nbsp;MHz and 2110–2155&nbsp;MHz are used instead, as the 1900&nbsp;MHz band was already used.<ref>The{{cite FCC'sweb |website=[[Federal Communications Commission]] |url=http://wireless.fcc.gov/services/aws/data/awsbandplan.pdf |title=Advanced Wireless Services bandplan](AWS) Band Plan |archive-url=https://web.archive.org/web/20100705121710/http://wireless.fcc.gov/services/aws/data/awsbandplan.pdf |archive-date=2010-07-05 |url-status=dead}}</ref> While UMTS2100 is the most widely deployed UMTS band, some countries' UMTS operators use the 850&nbsp;MHz (900&nbsp;MHz in Europe) and/or 1900&nbsp;MHz bands (independently, meaning uplink and downlink are within the same band), notably in the US by [[AT&T Mobility]], New Zealand by [[Telecom New Zealand]] on the [[XT Mobile Network]] and in Australia by [[Telstra]] on the [[Next G]] network. Some carriers such as [[T-Mobile US|T-Mobile]] use band numbers to identify the UMTS frequencies. For example, Band I (2100&nbsp;MHz), Band IV (1700/2100&nbsp;MHz), and Band V (850&nbsp;MHz).
 
UMTS-FDD is an acronym for Universal Mobile Telecommunications System (UMTS){{Snd}} [[frequency-division duplex]]ing (FDD) and a [[3GPP]] [[standardized]] version of UMTS networks that makes use of frequency-division duplexing for [[duplex (telecommunications)|duplex]]ing over an UMTS Terrestrial Radio Access ([[UTRA]]) air interface.<ref name="ts25.201">{{cite web |url=http://www.3gpp.org/DynaReport/25201.htm |title=TS 25.201 |access-date=2009-02-23 |author=3GPP}}</ref>
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Vodafone launched several UMTS networks in Europe in February 2004. [[MobileOne]] of [[Singapore]] commercially launched its 3G (W-CDMA) services in February 2005. [[New Zealand]] in August 2005 and [[Australia]] in October 2005.
 
[[AT&T Mobility]] utilized a UMTS network, with HSPA+, from 2005 until its shutdown in February 2022.
[[AT&T Wireless]] (now a part of [[Cingular]] Wireless) has deployed UMTS in several cities. Though advancements in its network deployment have been delayed due to the merger with Cingular, Cingular began offering [[HSDPA]] service in December 2005.
 
Rogers in [[Canada]] March 2007 has launched HSDPA in the Toronto Golden Horseshoe district on W-CDMA at 850/1900&nbsp;MHz and plan the launch the service commercial in the top 25 cities October, 2007.
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TD-CDMA is a part of IMT-2000, defined as IMT-TD Time-Division (IMT CDMA TDD), and is one of the three UMTS air interfaces (UTRAs), as standardized by the 3GPP in UTRA-TDD HCR. UTRA-TDD HCR is closely related to W-CDMA, and provides the same types of channels where possible. UMTS's HSDPA/HSUPA enhancements are also implemented under TD-CDMA.<ref>{{cite web|title=IPWireless Ships First Commercial 3GPP Chipset with Full HSDPA Implementation|url=http://www.ipwireless.com/news/press_020805.html|publisher=ipwireless.com|access-date=2008-02-28 |archive-url = https://web.archive.org/web/20070927010536/http://www.ipwireless.com/news/press_020805.html <!-- Bot retrieved archive --> |archive-date = 2007-09-27}}</ref>
 
In the United States, the technology has been used for public safety and government use in the [[New York City]] and a few other areas.{{needs update|date=October 2023}}<ref>{{cite web|url=http://www.fiercewireless.com/tech/ipwireless-introduces-td-cdma-network-a-box-targeting-rural-operators-public-safety|title=IPWireless introduces TD-CDMA Network in a Box targeting rural operators, public safety |website=Fiercewireless |date=2 May 2010 }}</ref> In Japan, IPMobile planned to provide TD-CDMA service in year 2006, but it was delayed, changed to TD-SCDMA, and bankrupt before the service officially started.
 
==== TD-SCDMA (UTRA-TDD 1.28 Mcps Low Chip Rate (LCR)) ====
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TD-SCDMA proponents also claim it is better suited for densely populated areas.<ref name="whatistdscdma"/> Further, it is supposed to cover all usage scenarios, whereas W-CDMA is optimised for symmetric traffic and macro cells, while TD-CDMA is best used in low mobility scenarios within micro or pico cells.<ref name="whatistdscdma"/>
TD-SCDMA is based on spread-spectrum technology which makes it unlikely that it will be able to completely escape the payment of license fees to western patent holders. The launch of a national TD-SCDMA network was initially projected by 2005<ref>[http://www.eetasia.com/ART_8800451183_499488_67aa06a5200701_no.HTM ''3G in China still held up''], EE Times Asia, Global Sources</ref> but only reached large scale commercial trials with 60,000 users across eight cities in 2008.<ref>[http://www.cellular-news.com/story/30163.php ''China Mobile to Test Td-scdma on 60,000 Phones from April 1,''], Cellular News</ref>▼
 
▲TD-SCDMA is based on spread-spectrum technology which makes it unlikely that it will be able to completely escape the payment of license fees to western patent holders. The launch of a national TD-SCDMA network was initially projected by 2005<ref>[http{{cite web |url=https://archive.eetasia.com/www.eetasia.com/ART_8800451183_499488_67aa06a5200701_noART_8800451183_499488_NT_f43f85da.HTM?from=ART_Next ''|title=3G in China still held up''], |first=Mike |last=Clendenin |date=30 January 2007 |website=EE Times Asia, Global Sources}}</ref> but only reached large scale commercial trials with 60,000 users across eight cities in 2008.<ref>[{{cite web |url=http://www.cellular-news.com/story/30163.php ''|title=China Mobile to Test TdTD-scdmaSCDMA on 60,000 Phones fromFrom April 1,''], |website=Cellular News |archive-url=https://web.archive.org/web/20080628212138/http://www.cellular-news.com/story/30163.php |archive-date=2008-06-28 |url-status=dead}}</ref>
On January 7, 2009, China granted a TD-SCDMA 3G licence to [[China Mobile]].<ref>[http://uk.reuters.com/article/internetNews/idUKTRE5061KP20090107 ''China issues 3G licences to main carriers''] The Reuters UK</ref>▼
 
▲On January 7, 2009, China granted a TD-SCDMA 3G licence to [[China Mobile]].<ref>[http{{cite web |url=https://ukwww.reuters.com/article/internetNews/oukin-uk-telecoms-china-idUKTRE5061KP20090107 ''|title=China issues 3G licences to main carriers''] The|first=Michael Reuters|last=Wei UK|date=January 7, 2009 |website=Reuters}}</ref>
 
On September 21, 2009, China Mobile officially announced that it had 1,327,000 TD-SCDMA subscribers as of the end of August, 2009.
 
TD-SCDMA is not commonly used outside of China.<ref>{{cite web |url=https://www.electronics-notes.com/articles/connectivity/3g-umts/td-scdma.php |title=What is 3G TD-SCDMA |website=Electronics Notes}}</ref>
While TD is primarily a China-only system, it may well be exported to developing countries. It is likely to be replaced with a newer [[TD-LTE]] system over the next 5 years.{{As of?|date=November 2021}}
 
===== Technical highlights =====
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TD-SCDMA also uses TDMA in addition to the CDMA used in WCDMA. This reduces the number of users in each timeslot, which reduces the implementation complexity of [[multiuser detection]] and beamforming schemes, but the non-continuous transmission also reduces [[coverage (telecommunication)|coverage]] (because of the higher peak power needed), mobility (because of lower [[power control]] frequency) and complicates [[radio resource management]] algorithms.
 
The "S" in TD-SCDMA stands for "synchronous", which means that uplink signals are synchronized at the base station receiver, achieved by continuous timing adjustments. This reduces the [[Interference (communication)|interference]] between users of the same timeslot using different codes by improving the [[Orthogonality#CommunicationsTelecommunications|orthogonality]] between the codes, therefore increasing system capacity, at the cost of some hardware complexity in achieving uplink synchronization.
 
===== History =====
On January 20, 2006, [[Ministry of Information Industry]] of the People's Republic of China formally announced that TD-SCDMA is the country's standard of 3G mobile telecommunication. On February 15, 2006, a timeline for deployment of the network in China was announced, stating pre-commercial trials would take place starting after completion of a number of test networks in select cities. These trials ran from March to October, 2006, but the results were apparently unsatisfactory. In early 2007, the Chinese government instructed the dominant cellular carrier, China Mobile, to build commercial trial networks in eight cities, and the two fixed-line carriers, [[China Telecom]] and [[China Netcom]], to build one each in two other cities. Construction of these trial networks was scheduled to finish during the fourth quarter of 2007, but delays meant that construction was not complete until early 2008.
 
The standard has been adopted by 3GPP since Rel-4, known as "UTRA TDD 1.28Mbps28&nbsp;Mbps Option".<ref name="whatistdscdma" />
 
On March 28, 2008, China Mobile Group announced TD-SCDMA "commercial trials" for 60,000 test users in eight cities from April 1, 2008. Networks using other 3G standards (WCDMA and CDMA2000 EV/DO) had still not been launched in China, as these were delayed until TD-SCDMA was ready for commercial launch.
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In January 2009, the [[Ministry of Industry and Information Technology of the People's Republic of China|Ministry of Industry and Information Technology]] (MIIT) in China took the unusual step of assigning licences for 3 different third-generation mobile phone standards to three carriers in a long-awaited step that is expected to prompt $41 billion in spending on new equipment. The Chinese-developed standard, TD-SCDMA, was assigned to China Mobile, the world's biggest phone carrier by subscribers. That appeared to be an effort to make sure the new system has the financial and technical backing to succeed. Licences for two existing 3G standards, W-CDMA and [[Evolution-Data Optimized|CDMA2000 1xEV-DO]], were assigned to [[China Unicom]] and China Telecom, respectively. Third-generation, or 3G, technology supports Web surfing, wireless video and other services and the start of service is expected to spur new revenue growth.
 
The technical split by MIIT has hampered the performance of China Mobile in the 3G market, with users and China Mobile engineers alike pointing to the lack of suitable handsets to use on the network.<ref>{{cite news |last1=Lau |first1=Justine |title=China Mobile trails on 3G technology |url=https://www.ft.com/content/f25fb1a6-7461-11dd-bc91-0000779fd18c |archive-url=https://ghostarchive.org/archive/20221210/https://www.ft.com/content/f25fb1a6-7461-11dd-bc91-0000779fd18c |archive-date=2022-12-10 |url-access=subscription |url-status=live |work=Financial Times |date=August 28, 2008}}{{subscription required}}</ref> Deployment of base stations has also been slow, resulting in lack of improvement of service for users.<ref>{{cite web |title=China's 3G Network Deployment Update{{Snd}} IHS Technology |url=https://technology.ihs.com/393444/chinas-3g-network-deployment-update |website=IHS Market: Technology |access-date=9 August 2019 |archive-date=9 August 2019 |archive-url=https://web.archive.org/web/20190809132931/https://technology.ihs.com/393444/chinas-3g-network-deployment-update |url-status=dead }}</ref> The network connection itself has consistently been slower than that from the other two carriers, leading to a sharp decline in market share. By 2011 China Mobile has already moved its focus onto TD-LTE.<ref>{{cite web |title=China Mobile Not Serious About TD-SCDMA, Betting Big on TD-LTE |url=https://technode.com/2011/05/09/china-mobile-not-serious-td-scdma-bet-big-ontd-lte/ |website=TechNode |date=9 May 2011}}</ref><ref name="CM TD-SCDMA CN 2"/> Gradual closures of TD-SCDMA stations started in 2016.<ref>{{cite web |date=2016|title=Closing of China Mobile 3G Base Stations Signifies End of China's Self-owned Standard |url=http://en.people.cn/n3/2016/0316/c90000-9030605.html |website=People's Daily Online }}</ref><ref name="CM TD-SCDMA CN 1"/>
 
===== Frequency bands & Deployments =====
{{further|UMTS frequency bands}}
The following is a list of [[mobile telephony|mobile telecommunications]] networks using third-generation TD-SCDMA / UMTS-TDD (LCR) technology.
 
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| A+<br /><small>(Band 34)</small>
| {{dts|Jan 2009}}
| (↓↑) 2010–2025&nbsp;MHz<br />{{fontcolour|red|Network is being phased out and is to be shutdown by 2025.}}<br /><ref name="CM TD-SCDMA CNLaunch 2CN">{{cite web |url=http://englishwww.caixinspreadtrum.com/2016en/news/press-releases/pr2008-03-14/100920062.html28 |title=China Mobile SaidAnnounces toCommercial BeginDeployment Closingof ItsTD-SCDMA 3G Base StationsTechnology |publisher=CaixinOnlineSpreadtrum Communications, Inc. |date=20162008-03-1428 |access-date=20162014-1207-17 |archive-date=2014-07-25 |archive-url=https://web.archive.org/web/20140725141648/http://www.spreadtrum.com/en/news/press-releases/pr2008-03-28 |url-status=dead}}</ref><ref name="CM TD-SCDMA CN 1">{{cite web|url=http://english.caixin.com/2014-12-15/100762382.html |title=China Mobile's Dead End on the 3G Highway |publisher=CaixinOnline |date=2014-12-15 |access-date=2016-12-17}}</ref><ref name="CM TD-SCDMA Launch CN 2">{{cite web|url=http://wwwenglish.spreadtrumcaixin.com/en/news/press-releases/pr20082016-03-2814/100920062.html |title=China Mobile AnnouncesSaid Commercialto DeploymentBegin ofClosing TD-SCDMAIts Technology3G Base Stations |publisher=Spreadtrum Communications, Inc.CaixinOnline |date=20082016-03-2814 |access-date=20142016-0712-17}}</ref><br />(↓↑) 2010–2025&nbsp;MHz<br />Network being phased out in favour of LTE.
|-
| {{fontcolour|grey|China Mobile}}
| {{flag|China}}
| {{fontcolour|grey|1900}}
| A-{{fontcolour|grey|A−<br /><small>(Band 33)</small>}}
| {{fontcolour|grey|{{dts|Jan 2009}} - {{dts|Dec 2013}}}}
| {{fontcolour|grey|(↓↑) 1900–1920&nbsp;MHz (Subset of Band 39)<br />Network upgraded to TDD-LTE (B39) via RRU Software Update.<br /><ref name="CM TD-SCDMA Launch CN"/><ref name="CM TD-SCDMA CN 1" /><ref name="CM TD-SCDMA CN 2" /><ref name="CM TD-SCDMA CN 3">{{cite web|url=https://www.gsma.com/solutions-and-impact/technologies/internet-of-things/wp-content/uploads/2013/03/Presentation-5-Madame-Hunag-China-Mobile.pdf |title=Implementing LTE FDD/TDD Convergence Network in the age of Mobile Inter net |publisher=China Mobile |date=2013-06-01 |access-date=2024-08-31}}</ref>}}
| <ref name="CM TD-SCDMA CN 2" /><ref name="CM TD-SCDMA CN 1" /><ref name="CM TD-SCDMA Launch CN"/><br />(↓↑) 1900–1920&nbsp;MHz (Subset of Band 39)<br />Previously used by [[Personal Handy-phone System|Xiaolingtong (PHS)]].<br />Network being phased out in favour of LTE.
|-
| {{fontcolour|graygrey|''none''}}
| {{flag|China}}
| {{fontcolour|graygrey|1900}}
| {{fontcolour|graygrey|F<br /><small>(Band 39)</small>}}
| {{fontcolour|graygrey|''N/A''}}
| {{fontcolour|graygrey|(↓↑) 1880–1920&nbsp;MHz<br />No deployments, later used for TD-LTE instead.<br />Upper half previously used by [[Personal Handy-phone System|Xiaolingtong (PHS)]]}}
|-
| {{fontcolour|graygrey|''none''China Mobile}}
| {{flag|China}}
| {{fontcolour|graygrey|2300}}
| {{fontcolour|graygrey|E<br /><small>(Band 40)</small>}}
| {{fontcolour|graygrey|''N/A''{{dts|Jan 2009}} - {{dts|Dec 2013}}}}
| {{fontcolour|graygrey|(↓↑) 2300–2400&nbsp;MHz<br />NoNetwork deployments,upgraded laterto usedTDD-LTE for(B40) via RRU Software Update.<br /><ref name="CM TD-LTESCDMA instead.Launch CN"/><ref name="CM TD-SCDMA CN 1" /><ref name="CM TD-SCDMA CN 2" /><ref name="CM TD-SCDMA CN 3" />}}
|-
| Xinwei<br /><small>(CooTel)</small>
| {{flag|Nicaragua}}
| 1800
| {{fontcolour|gray|''N/A''}}
| {{dts|Apr 2016}}
| <ref>{{cite web|url=https://www.telegeography.com/products/commsupdate/articles/2016/04/29/xinwei-belatedly-launches-as-cootel-in-nicaragua/ |title=Xinwei belatedly launches as CooTel in Nicaragua |publisher=TeleGeography |date=2016-04-29 |access-date=2016-04-29}}</ref><ref>{{cite web|url=https://www.telegeography.com/products/commsupdate/articles/2016/01/19/xinwei-finally-stages-user-trials-will-trade-under-cootel-brand/ |title=Xinwei finally stages user trials; will trade under CooTel brand |publisher=TeleGeography |date=2016-01-19 |access-date=2016-01-20}}</ref><ref>{{cite web|url=https://www.telegeography.com/products/commsupdate/articles/2015/10/14/xinwei-outlines-november-launch-plan-for-nicaragua/ |title=Xinwei outlines November launch plan for Nicaragua |publisher=TeleGeography |date=2015-10-14 |access-date=2015-10-14}}</ref><br />(↓↑) 1785–1805&nbsp;MHz
|}
 
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UMTS-TDD tends to be allocated frequency intended for mobile/wireless Internet services rather than used on existing cellular frequencies. This is, in part, because TDD duplexing is not normally allowed on [[Mobile phone|cellular]], [[Personal Communications Service|PCS]]/PCN, and 3G frequencies. TDD technologies open up the usage of left-over unpaired spectrum.
 
Europe-wide, several bands are provided either specifically for UMTS-TDD or for similar technologies. These are 1900&nbsp;MHz and 1920&nbsp;MHz and between 2010&nbsp;MHz and 2025&nbsp;MHz. In several countries the 2500-{{En dash}}2690&nbsp;MHz band (also known as MMDS in the USA) have been used for UMTS-TDD deployments. Additionally, spectrum around the 3.5&nbsp;GHz range has been allocated in some countries, notably Britain, in a technology-neutral environment. In the Czech Republic UTMS-TDD is also used in a frequency range around 872&nbsp;MHz.<ref>{{cite web|title=T-Mobile launches UMTS TDD network in the Czech Republic|url=http://www.geekzone.co.nz/content.asp?contentid=4693|date=21 June 2005}}</ref>
 
==== Deployment ====
UMTS-TDD has been deployed for public and/or private networks in at least nineteen countries around the world, with live systems in, amongst other countries, Australia, Czech Republic, France, Germany, Japan, New Zealand, Botswana, South Africa, the UK, and the USA.
 
Deployments in the US thus far have been limited. It has been selected for a public safety support network used by emergency responders in New York,<ref>{{cite web|title=Northrop Grumman Wins $500 Million New York City Broadband Mobile Wireless Contract|url=http://www.ipwireless.com/news/press_091206.html|publisher=ipwireless.com|access-date=2008-02-28|archive-date=2007-11-24|archive-url=https://web.archive.org/web/20071124072118/http://www.ipwireless.com/news/press_091206.html|url-status=dead}}</ref> but outside of some experimental systems, notably one from [[Nextel]], thus far the WiMAX standard appears to have gained greater traction as a general mobile Internet access system.
 
==== Competing standards ====
A variety of Internet-access systems exist which provide broadband speed access to the net. These include WiMAX and [[HIPERMAN]]. UMTS-TDD has the advantages of being able to use an operator's existing UMTS/GSM infrastructure, should it have one, and that it includes UMTS modes optimized for circuit switching should, for example, the operator want to offer telephone service. UMTS-TDD's performance is also more consistent. However, UMTS-TDD deployers often have regulatory problems with taking advantage of some of the services UMTS compatibility provides. For example, the UMTS-TDD spectrum in the UK cannot be used to provide telephone service, though the regulator [[OFCOM]] is discussing the possibility of allowing it at some point in the future. Few operators considering UMTS-TDD have existing UMTS/GSM infrastructure.
 
Additionally, the WiMAX and HIPERMAN systems provide significantly larger bandwidths when the mobile station is in close proximity tonear the tower.
 
Like most mobile Internet access systems, many users who might otherwise choose UMTS-TDD will find their needs covered by the ad hoc collection of unconnected Wi-Fi access points at many restaurants and transportation hubs, and/or by Internet access already provided by their mobile phone operator. By comparison, UMTS-TDD (and systems like WiMAX) offers mobile, and more consistent, access than the former, and generally faster access than the latter.
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UMTS networks are often combined with GSM/EDGE, the latter of which is also a part of IMT-2000.
 
The UE ([[User equipment|User Equipment]]) interface of the [[Radio access network|RAN]] (Radio Access Network) primarily consists of [[Radio Resource Control|RRC]] (Radio Resource Control), [[PDCP]] (Packet Data Convergence Protocol), [[Radio Link Control|RLC]] (Radio Link Control) and MAC (Media Access Control) protocols. RRC protocol handles connection establishment, measurements, radio bearer services, security and handover decisions. RLC protocol primarily divides into three Modes{{snd}} Transparent Mode (TM), Unacknowledge Mode (UM), Acknowledge Mode (AM). The functionality of AM entity resembles TCP operation whereas UM operation resembles UDP operation. In TM mode, data will be sent to lower layers without adding any header to [[Service data unit|SDU]] of higher layers. MAC handles the scheduling of data on air interface depending on higher layer (RRC) configured parameters.
 
The set of properties related to data transmission is called Radio Bearer (RB). This set of properties decides the maximum allowed data in a TTI (Transmission Time Interval). RB includes RLC information and RB mapping. RB mapping decides the mapping between RB<->logical channel<->transport channel. Signaling messages are sent on Signaling Radio Bearers (SRBs) and data packets (either CS or PS) are sent on data RBs. RRC and [[Non Access Stratum|NAS]] messages go on SRBs.
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The 2100&nbsp;MHz band (downlink around 2100&nbsp;MHz and uplink around 1900&nbsp;MHz) allocated for UMTS in Europe and most of Asia is already used in North America. The 1900&nbsp;MHz range is used for 2G ([[Personal Communications Service|PCS]]) services, and 2100&nbsp;MHz range is used for satellite communications. Regulators have, however, freed up some of the 2100&nbsp;MHz range for 3G services, together with a different range around 1700&nbsp;MHz for the uplink. {{update after|2012|6|2}}
 
AT&T Wireless launched UMTS services in the United States by the end of 2004 strictly using the existing 1900&nbsp;MHz spectrum allocated for 2G PCS services. Cingular acquired AT&T Wireless in 2004 and has since then launched UMTS in select US cities. Cingular renamed itself AT&T Mobility and rolled out<ref>{{cite web|last1=Vries|first1=Lloyd|title=From AT&T To Cingular And Back Again|url=http://www.cbsnews.com/news/from-att-to-cingular-and-back-again/|website=CBS News|date=12 January 2007 |access-date=30 June 2017}}</ref> some cities with a UMTS network at 850&nbsp;MHz to enhance its existing UMTS network at 1900&nbsp;MHz and now offers subscribers a number of dual-band UMTS 850/1900 phones.
 
T-Mobile's rollout of UMTS in the US was originally focused on the 1700&nbsp;MHz band. However, T-Mobile has been moving users from 1700&nbsp;MHz to 1900&nbsp;MHz (PCS) in order to reallocate the spectrum to 4G [[LTE (telecommunication)|LTE]] services.<ref>{{cite web |url=https://www.telegeography.com/products/commsupdate/articles/2015/06/24/t-mobile-shifting-1700mhz-hspa-users-to-1900mhz-band/ |title=T-Mobile shifting 1700&nbsp;MHz HSPA+ users to 1900&nbsp;MHz band |publisher=TeleGeography |date=2015-06-24 |access-date=2016-04-07}}</ref>
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UMTS phones (and data cards) are highly portable{{snd}} they have been designed to roam easily onto other UMTS networks (if the providers have roaming agreements in place). In addition, almost all UMTS phones 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{{Snd}} Europe initially used 2100&nbsp;MHz while the most carriers in the USA use 850&nbsp;MHz and 1900&nbsp;MHz. T-Mobile has launched a network in the US operating at 1700&nbsp;MHz (uplink) /2100&nbsp;MHz (downlink), and these bands also have been adopted elsewhere in the US and in Canada and Latin America. 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 United States will likely not be operable elsewhere and vice versa. There are now 11 different frequency combinations used around the world{{snd}} including frequencies formerly used solely for 2G services.
 
UMTS phones can use a [[Universal Subscriber Identity Module]], USIM (based on GSM's [[SIM card]]) and also work (including UMTS services) with GSM SIM cards. This is a global standard of identification, and enables a network to identify and authenticate the (U)SIM in the phone. 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 (U)SIM provides storage space for phone book contact. Handsets can store their data on their own memory or on the (U)SIM card (which is usually more limited in its phone book contact information). A (U)SIM can be moved to another UMTS or GSM phone, and the phone will take on the user details of the (U)SIM, meaning it is the (U)SIM (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 UMTS network{{snd}} using a pre-release specification,<ref>{{citation|author=Hsiao-Hwa Chen|publisher=John Wiley and Sons|year=2007|title=The Next Generation CDMA Technologies|isbn=978-0-470-02294-8|pages=105–106}}</ref> it was initially incompatible with the UMTS standard at the radio level but used standard USIM cards, meaning USIM card based roaming was possible (transferring the USIM card into a UMTS or GSM phone when travelling). Both NTT DoCoMo and SoftBank Mobile (which launched 3G in December 2002) now use standard UMTS.
 
=== Handsets and modems ===
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The main competitor to UMTS is CDMA2000 (IMT-MC), which is developed by the [[3GPP2]]. Unlike UMTS, CDMA2000 is an evolutionary upgrade to an existing 2G standard, cdmaOne, and is able to operate within the same frequency allocations. This and CDMA2000's narrower bandwidth requirements make it easier to deploy in existing spectra. 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&nbsp;MHz in each direction. A standard UMTS system would saturate that spectrum. Where CDMA2000 is deployed, it usually co-exists with UMTS. 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.
 
Another competitor to UMTS is [[EDGE]] (IMT-SC), which is an evolutionary upgrade to the 2G GSM system, leveraging existing GSM spectrums. 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 rather than having to install almost all brand-new equipment to deliver UMTS. However, being developed by 3GPP just as UMTS, EDGE is not a true competitor. Instead, it is used as a temporary solution preceding UMTS roll-out or as a complement for rural areas. This is facilitated by the fact that GSM/EDGE and UMTS specifications are jointly developed and rely on the same core network, allowing dual-mode operation including [[vertical handover]]s. <!-- 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 a nationwide 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. This should be part of the EDGE article, not UMTS. -->
 
China's [[TD-SCDMA]] standard is often seen as a competitor, too. TD-SCDMA has been added to UMTS' Release 4 as UTRA-TDD 1.28 Mcps Low Chip Rate (UTRA-TDD LCR). Unlike [[TD-CDMA]] (UTRA-TDD 3.84 Mcps High Chip Rate, UTRA-TDD HCR) which complements W-CDMA (UTRA-FDD), it is suitable for both micro and macrocells. However, the lack of vendors' support is preventing it from being a real competitor.
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* Location services
* Call service: compatible with Global System for Mobile Communications ([[GSM]]), based on Universal Subscriber Identity Module (USIM)
* Voice quality features{{Snd}} [[Tandem Free Operation]]
* Frequency 2.1&nbsp;GHz
 
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* 64 QAM, MIMO
* Voice over [[High Speed Packet Access|HSPA]]
* CPC{{Snd}} continuous packet connectivity
* FRLC{{Snd}} Flexible RLC
 
=== Release 8 ===
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* [[List of UMTS networks]]
* [[3GPPLTE (telecommunication)|Long Term Evolution]], the 3GPP project[[4G]] tosuccessor evolvefor UMTS towardsand [[4GCDMA2000]] capabilities.▼
* 3GPP: the body that manages the UMTS standard.
▲* [[3GPP Long Term Evolution]], the 3GPP project to evolve UMTS towards [[4G]] capabilities.
* [[Generic Access Network|GAN]]/UMA: A standard for running GSM and UMTS over wireless LANs.
* [[Opportunity-Driven Multiple Access]], [[(ODMA]]): a UMTS [[Time-division duplex|TDD]] mode communications [[Wireless ad hoc network|relaying]] protocol
* [[HSDPA]], [[HSUPA]]: updates to the W-CDMA air interface.
* [[PDCP]]
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* [http://www.3gsmworldcongress.com/ 3GSM World Congress]
* [https://web.archive.org/web/20080922193110/http://www.spectran.com/Frequenzplan-UMTS_en.shtml UMTS Provider Chart]
* [https://sites.google.com/site/lteencyclopedia/ LTE Encyclopedia] {{Webarchive|url=https://web.archive.org/web/20160127122842/https://sites.google.com/site/lteencyclopedia/ |date=2016-01-27 }}
* [http://www.tdscdma-forum.org/EN/index.asp TD-SCDMA Forum]
* [https://web.archive.org/web/20061006123942/http://www.tdscdma-alliance.org/english/ TD-SCDMA Industry Alliance]
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