Editing UMTS (section)

=== W-CDMA (UTRA-FDD) ===
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? |work=About Us |publisher=GSMA.com |access-date=2014-06-24 |url-status=dead |archive-url=https://web.archive.org/web/20140625040221/http://www.gsma.com/aboutus/gsm-technology/3gwcdma |archive-date=2014-06-25}}</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>{{cite web |website=[[Federal Communications Commission]] |url=http://wireless.fcc.gov/services/aws/data/awsbandplan.pdf |title=Advanced Wireless Services (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>

W-CDMA is the basis of Japan's [[NTT DoCoMo]]'s [[Freedom of Mobile Multimedia Access|FOMA]] service and the most-commonly used member of the Universal Mobile Telecommunications System (UMTS) family and sometimes used as a synonym for UMTS.<ref>3GPP notes that "there currently existed many different names for the same system (eg FOMA, W-CDMA, UMTS, etc)"; {{cite web|title=Draft summary minutes, decisions and actions from 3GPP Organizational Partners Meeting#6, Tokyo, 9 October 2001|author=[[3GPP]]|url=http://www.3gpp.org/ftp/op/OP_07/DOCS/pdf/OP6_13r1.pdf|pages=7}}</ref> It uses the DS-CDMA channel access method and the FDD duplexing method to achieve higher speeds and support more users compared to most previously used [[time-division multiple access]] (TDMA) and [[time-division duplex]] (TDD) schemes.

While not an evolutionary upgrade on the airside, it uses the same [[core network]] as the [[2G]] GSM networks deployed worldwide, allowing [[dual-mode mobile]] operation along with GSM/[[Enhanced Data Rates for GSM Evolution|EDGE]]; a feature it shares with other members of the UMTS family.

==== Development ====
In the late 1990s, W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network [[FOMA]]. Later NTT DoCoMo submitted the specification to the [[International Telecommunication Union]] (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards, as an alternative to CDMA2000, EDGE, and the short range [[DECT]] system. Later, W-CDMA was selected as an air interface for [[UMTS frequency bands|UMTS]].

As NTT DoCoMo did not wait for the finalisation of the 3G Release 99 specification, their network was initially incompatible with UMTS.<ref>{{citation|author=Hsiao-Hwa Chen|title=The Next Generation CDMA Technologies|publisher=John Wiley and Sons|year=2007|isbn=978-0-470-02294-8|pages=105–106}}</ref> However, this has been resolved by NTT DoCoMo updating their network.

Code-Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by [[Qualcomm]], the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones and its early [[cdmaOne|IS-95]] air interface standard has evolved into the current CDMA2000 (IS-856/IS-2000) standard. Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA ([[3rd Generation Partnership Project|3GPP]]) and CDMA2000 ([[3rd Generation Partnership Project 2|3GPP2]]) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries {{as of|2006|lc=on}}. However, divergent requirements resulted in the W-CDMA standard being retained and deployed globally. W-CDMA has then become the dominant technology with 457 commercial networks in 178 countries as of April 2012.<ref>{{cite web|url=http://www.gsacom.com/downloads/pdf/HSPA_operator_commitments_160412.php4|title=GSM Association HSPA Market update April 2012}}</ref> Several CDMA2000 operators have even converted their networks to W-CDMA for international roaming compatibility and smooth upgrade path to [[LTE (telecommunication)|LTE]].

Despite incompatibility with existing air-interface standards, late introduction and the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has become the dominant standard.

==== Rationale for W-CDMA ====
W-CDMA transmits on a pair of 5&nbsp;MHz-wide radio channels, while CDMA2000 transmits on one or several pairs of 1.25&nbsp;MHz radio channels. Though W-CDMA does use a [[direct-sequence spread spectrum|direct-sequence]] CDMA transmission technique like CDMA2000, W-CDMA is not simply a wideband version of CDMA2000 and differs in many aspects from CDMA2000. From an engineering point of view, W-CDMA provides a different balance of trade-offs between cost, capacity, performance, and density{{citation needed|date=November 2011}}; it also promises to achieve a benefit of reduced cost for video phone handsets. W-CDMA may also be better suited for deployment in the very dense cities of Europe and Asia. However, hurdles remain, and [[cross-licensing]] of [[patent]]s between Qualcomm and W-CDMA vendors has not eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.<ref>{{cite web|url=https://www.infoworld.com/article/2205181/qualcomm-says-it-doesn-t-need-nokia-patents-2.html|title=Qualcomm says it doesn't need Nokia patents}}</ref>

W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.

==== Deployment ====
The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in [[Japan]] in 2001.

Elsewhere, W-CDMA deployments are usually marketed under the UMTS brand.

W-CDMA has also been adapted for use in satellite communications on the U.S. [[Mobile User Objective System]] using geosynchronous satellites in place of cell towers.

[[J-Phone]] Japan (once [[Vodafone]] and now [[SoftBank Mobile]]) soon followed by launching their own W-CDMA based service, originally branded "Vodafone Global Standard" and claiming UMTS compatibility. The name of the service was changed to "Vodafone 3G" (now "SoftBank 3G") in December 2004.

Beginning in 2003, [[Hutchison Whampoa]] gradually launched their upstart UMTS networks.
 
Most countries have, since the ITU approved of the 3G mobile service, either "auctioned" the radio frequencies to the company willing to pay the most, or conducted a "beauty contest"{{snd}} asking the various companies to present what they intend to commit to if awarded the licences. This strategy has been criticised for aiming to drain the cash of operators to the brink of bankruptcy in order to honour their bids or proposals. Most of them have a time constraint for the rollout of the service{{snd}} where a certain "coverage" must be achieved within a given date or the licence will be revoked.

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.

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.

[[TeliaSonera]] opened W-CDMA service in [[Finland]] October 13, 2004, with speeds up to 384&nbsp;kbit/s. Availability only in main cities. Pricing is approx. €2/MB.{{Citation needed|date=January 2009}}

[[SK Telecom]] and [[KTF]], two largest mobile phone service providers in [[South Korea]], have each started offering W-CDMA service in December 2003. Due to poor coverage and lack of choice in handhelds, the W-CDMA service has barely made a dent in the Korean market which was dominated by CDMA2000. By October 2006 both companies are covering more than 90 cities while [[SK Telecom]] has announced that it will provide nationwide coverage for its WCDMA network in order for it to offer SBSM (Single Band Single Mode) handsets by the first half of 2007. [[KT Freecel]] will thus cut funding to its CDMA2000 network development to the minimum.

In [[Norway]], [[Telenor]] introduced W-CDMA in major cities by the end of 2004, while their competitor, [[NetCom (Norway)|NetCom]], followed suit a few months later. Both operators have 98% national coverage on EDGE, but Telenor has parallel WLAN roaming networks on GSM, where the UMTS service is competing with this. For this reason Telenor is dropping support of their WLAN service in Austria (2006).

[[Maxis Communications]] and [[Celcom]], two mobile phone service providers in [[Malaysia]], started offering W-CDMA services in 2005.

In [[Sweden]], [[Telia Company|Telia]] introduced W-CDMA in March 2004.