UMTS
| ·UMTS | Top |
UMTS(Universal Mobile Telecommunications System)，意即通用移动通信系统。UMTS是国际标准化组织3GPP制定的全球3G标准之一。作为一个完整的3G移动通信技术标准，UMTS并不仅限于定义空中接口。它的主体包括CDMA接入网络和分组化的核心网络等一系列技术规范和接口协议。除WCDMA作为首选空中接口技术获得不断完善外，UMTS还相继引入了TD-SCDMA和HSDPA技术。
一种第三代（3G）移动电话技术[1]。它使用WCDMA作为底层标准，由 3GPP定型，代表欧洲对ITU IMT-2000 关于3G蜂窝无线系统需求的回应。
UMTS有时也叫3GSM，强调结合了3G技术而且是GSM标准的后续标准。UMTS 分组交换系统是由 GPRS 系统所演进而来，故系统的架构颇为相像。
绪言
本条目主要讨论围绕源于GSM网络基础结构和W-CDMA空中接口的UMTS标准的有关技术商业用途和其他方面的内容。任何仅仅和W-CDMA接口本身紧密相关的议题都在W-CDMA中更好地被阐述。
由于UMTS变化很快，本页面的信息可能会比实际状况滞后二到三个月的时间。强烈建议读者发表自己的观点和附加的独立研究；所有的发信都被鼓励追加到本页面以完善本条目。积极更新的读者请您附加上适当的修改时间以帮助其他读者建立他们的时间线，更好理解本条目内容。
| ·UMTS特性 | Top |
UMTS支持1920kbps的传输速率 (不是经常看到的2Mbps), 然而在现实高负载系统中典型的最高速率大约只有384Kbps。即使这样数据速了已经高出GSM纠错数据信道14.4kbps或者多个14.4 kbps组成的HSCSD信道, 真正能够实现价格可接受的移动WWW访问和MMS。 UMTS实现的前提是现在广泛使用GSM移动电话系统，属于2G技术。还有一个叫做GPRS的从2G演进的途径。（可以看作2.5G） GPRS支持更好的数据速率(理论上最大可以到140.8kbps，实际上能实现接近56Kbps)，数据封装好于面向连接。 GPRS已经在很多GSM网络部署。
今天的UMTS网络未来可能升级成HSDPA,有时也叫3.5G。 它可以实现下行链路大于10Mbps的传输速度。
UMTS在市场运作上强调移动视频电话会议实现的可能性,尽管实际上这项很有潜力的服务还有很多没有经过测试验证。
UMTS其它可能的应用还有音乐下载和视频电话。
| ·UMTS实际运营情况 | Top |
3是一个从3G网络成长起来的原属于和记黄埔（现在是合作伙伴）的运营商。它很快就要在全球启动其他UMTS网络(2004年12月) 包括 澳大利亚, 奥地利, 丹麦, 香港, 以色列, 意大利, 葡萄牙, 爱尔兰共和国和瑞典. 大多数西欧GSM运营商打算未来升级到UMTS，因为它比较接近于GSM2G标准。
2003年12月, T-Mobile启动了他的奥地利UMTS网络，英国和德国的网络也在调试中。
2004年2月，沃达丰开始在包括英国德国荷兰瑞典在内的几个欧洲市场大范围部署UMTS。在葡萄牙，UMTS已经先于Euro 2004运营。
非洲第一个UMTS网络于2004年11月在毛利求斯投入运行,由中国的华为提供全网设备，紧随其后Vodacom2004年12月在南非推出3G服务。
在NTT DoCoMo事先授权下, 美国 AMPS/TDMA/GSM 运营商 AT&T Wireless 2004年底以前必须在四个主要的城市建立和运营UMTS网络。CTIA 2004年会上, AT&T Wireless声明他们的UMTS网络在1900MHz频段独立运行，已经计划2004年底启动UMTS服务。 2004七月, AT&T Wireless (现在属于Cingular) 在 西雅图 (华盛顿), 旧金山 (加利福尼亚), 底特律 (密歇根), 菲尼科斯 (亚利桑那), 圣地亚哥 (加利福尼亚) and 达拉斯 (德克萨斯)成功启动UMTS服务。
2005年第一季度德国移动运营商沃达丰D2，O2－de相继推出UMTS服务。
与AT&T Wireless合并之后, Cingular已经声明计划2005年开始部署使用HSDPA技术的UMTS网络。 区别于AT&T开发的 UMTS, Cingular拓展了UMTS的频率范围到1900MHz和850MHz两个频段。
T-Mobile USA计划到2007年开始部署UMTS。
运营商开始销售整合3G和Wi-Fi服务的移动互联网产品。笔记本电脑用户可以买到他们提供的UMTS Modem，还有客户端软件用于自动探测网络状态，以便在有Wi-Fi信号时自动从3G网络切换。开始Wi-FI被认为是3G的一个竞争对手，但是现在不得不承认，运营商为了提供比单纯UMTS更有竞争力的产品，他们必须或者拥有或者租用别人的Wi-Fi网络。
| ·UMTS技术 | Top |
注意: UMTS的许多技术特征是所有W-CDMA变种所共同具有的，更多信息请参看条目W-CDMA。以下仅讨论UMTS特有的一些技术特征，它们不适用于FOMA或其他W-CDMA变种。
简单的说，UMTS结合了W-CDMA的空中接口(移动电话和基站的空中通信协议)、GSM系统的移动应用核心部分(MAP,参见en:MAP)（此协议提供从用户或者到用户的呼叫路由功能），以及GSM的语音编码算法例如自适应多速率(AMR)和加强全速率(EFR)（它们定义了将语音数字化、压缩、编码的方法）。换言之，W-CDMA（依照IMT-2000的定义）只是一个空中接口，而UMTS才是一个用于3G全球移动通讯的完整协议栈，可用来代替GSM。然而，实际上也经常将W-CDMA作为所有采用该空中接口的3G标准族的总称，包括UMTS，FOMA和J-Phone.
与其它W-CDMA变种一样，UMTS使用一对5 MHz信道，上行信道在1900 MHz附近，下行信道在2100 MHz附近。相比之下，CDMA2000则可在每个方向上使用一个或多个1.25 MHz信道，因此UMTS常因为它的高带宽需求而受到批评。
UMTS原先规定的频段为上行1885-2025 MHz，下行2110-2200 MHz。目前的频段分配可参见[1]。
对现有的GSM运营商有一个简单但比较昂贵的升级到UMTS的方案：大部分现有的基础设施可以维持原状，但是获得频段授权和在现有基站塔上完成UMTS覆盖的费用可能极其高昂。
UMTS与GSM的一个主要的差别是由无线接口等构成的通用无线接入网(GRAN)，它能够联入不同的骨干网络，如英特网、ISDN、GSM或者UMTS网络。GRAN包含OSI模型的低三层（物理层、数据链路层、网络层）。 网络层(OSI 3)协议包括RRM协议(RRM)，它负责管理移动设备与固定网络之间的承载信道，并完成切换功能。
互操作性和全球漫游
在空中接口层，UMTS兼容GSM。尽管市场上现在的UMTS手机都是UMTS/GSM双模手机但是他们都能在纯GSM的网络中很好的工作。如果一个UMTS用户漫游到没有UMTS覆盖的地方，他的手机会自动切换到GSM模式（要支付漫游费用）。如果用户在通话中漫游出了UMTS覆盖范围，那么电话将会切换到有GSM覆盖的区域去。普通GSM手机不能在UMTS网络使用。
沃达丰－日本 (前身 J-Phone) 有一个使用W-CDMA并兼容UMTS的3G网络。这使得UMTS成为真正的全球无线标准。当前的全球无线标准, GSM适用于除了日本和韩国以外多数国家。
NTT DoCoMo的3G网络, FOMA,同样使用W-CDMA, 但是不兼容UMTS。 然而NTT DoCoMo拥有AT&T无线实验室18的股份原来还持有3UK20的股份。 这些在国外的资本为未来的全球漫游解决方案提供一个测试平台. (到2004年12月)
所有UMTS/GSM双模电话都应当兼容现存GSM标准SIM卡. 有时你被允许在同一个运营商网络里使用SIM卡在UMTS网络漫游。
在美国, 由于现存的对频率使用的限制只是运营商AT&T无线的网络只能在1900MHz频段。 为美国市场设计的UMTS手机跟其他区域的有所区别，这也反映了当前美国的GSM手机和GSM网络使用不同与其他国家的状况。尽管联邦通讯委员会（FCC）已经决议允许附加2100MHz频段给UMTS，大多数获得UMTS授权的运营商好像打算放弃承担保证实现全球漫游的责任。
尽管欧亚手机可以实现漫游，但是到2004年12月在美国实现与欧亚漫游可能性还不大。
频谱分配
超过120份许可证已经颁发给全世界的运营商（截至2004年），特别是基于GSM的无线访问技术W-CDMA。由于技术还在不断的完善中，所以政客过于仓促的卖出许可，成百上千亿美元的许可证费用流入公共预算。 仅仅在德国，许可证费用就高达508亿欧元。运营商被期望在2005年开始从这些许可盈利。
在北美ITU已经为UMTS分配了频段。 1900MHz范围应用于2G (PCS) 服务, 2100 MHz 范围用于卫星通讯。 尽管在北美UMTS将要不得不与现存2G服务共享1900MHz频段，但是国际上正试图为3G服务释放2100MHz频段。 2G GSM 服务因使用900MHz和1800MHz，因此不再共享任何UMTS服务的频段。
到为3G分配新的特定频段之前，北美还没有厂商回答UMTS使用那些频率。 AT&T Wireless 2004年底已经确定在美国 确定为UMTS服务启用了为2GPCS服务使用的1900 MHz频段。最初在加拿大展示的UMTS服务也使用1900MHz频段。
其他竞争标准
除UMTS还有其他的3G标准，例如CDMA2000和专有系统包括Arraycom的iBurst， Flarion and WCDMA-TDD (无线IP)。然而，人们还是比较期望3GSM/UMTS成为取代当前GSM标准的统治地位成为事实的3G。
CDMA2000和W-CDMA是ITU认可的IMT-20003G标准族成员 ,另外的还有EDEG和中国自有3G标准TD-SCDMA。
CDMA2000改良升级自CDMA1x,不需要新的频段分配，可以稳定运行在现有PCS频段。
大多数现有的GSM运营商因为高昂的频段和设备费用对UMTS持观望态度。
多数北美GSM运营商已接受EDGE作为暂定3G解决方案。 AT&T无线2003年本国范围内开始运行EDGE，Cingular 也在本国内运行，T-Mobile美国 计划全美范围提供EDGE。Rogers Wireless在2003年晚期开始在加拿大范围内投入运行EDGE服务。EDGE的好处是它有效利用现有GSM频段而且兼容现有GSM手机。EDGE为GSM运营商与CDMA2000竞争提供了一个短期的升级途经。
| ·问题 | Top |
运营商首先面对的问题:
超重的手机只有可怜的待机时间;
若要完美实现UMTS的VOD功能, 每100米要设立一个基站。在都市区域经济上可行，在人口较少的郊区和乡下不可行。
来自Wi-Fi宽带网络的竞争;
客户缺少对3G重要的需求
Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. It uses W-CDMA as the underlying standard, is standardized by the 3GPP, and represents the European/Japanese 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.
Due to the rapid nature of UMTS development in the market place, some information on this page may become quickly outdated. Readers' discretion and additional independent research is strongly advised; you are encouraged to return and add updates to this page. Contributors are also advised to timestamp their contributions when appropriate in order to help readers to determine the age of the information.
[edit]
Features
UMTS supports up to 1920 kbit/s data transfer rates (and not 2 Mbit/s as frequently seen), although at the moment users in the real networks can expect performance up to 384 kbit/s - in Japan upgrades to 3 Mbit/s are in preparation. However, this is still much greater than the 14.4 kbit/s of a single GSM error-corrected circuit switched data channel or multiple 14.4 kbit/s channels in HSCSD, and - in competition to other network technologies such as CDMA-2000, 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, CDMA, PDC, PHS and other 2G technologies deployed in different countries. In the case of GSM, there is an evolution path from 2G, called GPRS, also known as 2.5G. GPRS supports a much better data rate (up to a theoretical maximum of 140.8kbit/s, though typical rates are closer to 56kbit/s) and is packet switched rather than connection oriented (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 new "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".
In 2006, UMTS networks in Japan will be upgraded with High Speed Downlink Packet Access (HSDPA), sometimes known as 3.5G. This will make a downlink transfer speed of up to 14.4 Mbit/s possible. Work is also progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access (HSUPA)
In 2006, Vodacom in South Africa is also working towards implementing High Speed Downlink Packet Access (HSDPA).
In Austria, Mobilkom Austria already implemented and deployed HSDPA for public usage.
Marketing material for UMTS has emphasised the possibility of 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.
Real-world implementations
The first large scale real-life commercial UMTS network in the world went live in 2001 in Japan, operated by NTT DoCoMo.
In December 2003, T-Mobile launched UMTS in Austria, and began trials in the UK and Germany. Also, in November 2005 the T-Mobile UMTS network in the Netherlands went live (however, this was not a commercial launch, but meant to meet regulatory requirements imposed upon the spectrum auction).
In February 2004, Vodafone began a wide-scale UMTS launch in several European markets, including the UK, Germany, The Netherlands and Sweden. In Portugal, UMTS was launched just before the Euro 2004 began.
The first UMTS network in Poland was launched in 2004 by Plus GSM, but coverage was still limited to Warsaw. In April 2005, Era GSM launched another UMTS network in Warsaw, providing cheap (about 20 euros per month) internet access, among other 3G services. In January 2006 most of top major cities are covered by Era GSM, Orange and Plus GSM.
In the Czech Republic, UMTS was launched by T-Mobile in 2005.
The first UMTS network in Africa was launched on the island of Mauritius in November 2004, followed by Vodacom's launch of 3G services in South Africa in December 2004.
In Finland, UMTS licenses were provided by the government free of charge. In 2004, Elisa Oyj and TeliaSonera began deploying commercial UMTS networks, and in 2005 Dna Finland began commercial UMTS service.
Under a previous agreement with NTT DoCoMo, US provider AT&T Wireless (now Cingular) was required to build and market UMTS networks in four major United States cities by the end of 2004. At CTIA 2004, Cingular announced that their 3G network would be a 1900-only implementation of UMTS and would launch by the end of that year as planned. As of January 2006, Cingular has deployed UMTS networks in Dallas, Detroit, Phoenix, San Diego, San Francisco, and Seattle.
Because the US has not yet provided new spectrum for UMTS, it must share the 850MHz and 1900MHz bands allocated for cellular communication in the US with existing 1G and 2G networks. The UMTS requirement for 5 MHz frequency slots, much larger than that required for existing networks, can create difficulty for US operators.
In Singapore, Singapore Telecommunications started their trial during December 2004 and it was successfully launched during March 2005 followed by StarHub and MobileOne.
Operators are starting to sell mobile internet products that combine 3G and Wi-Fi in one service. Laptop owners are sold a UMTS modem and given a client program that detects the presence of a Wi-Fi network and switches between 3G and Wi-Fi when available. Initially Wi-Fi was seen as a competitor to 3G, but it is now recognised that as long as the operator owns or leases the Wi-Fi network, they will be able to offer a more competitive product than with UMTS only. Nokia has forecasted that UMTS devices will make one sixth of all cellular phones by the end of 2006.
Technology
The following information does not apply to non-UMTS systems that use the W-CDMA air interface, such as FOMA
UMTS combines the W-CDMA air interface, GSM's Mobile Application Part (MAP) core, and the GSM family of speech codecs.
Note that many wireless technologies use W-CDMA as their air interface, including FOMA and J-Phone.
Like other real-world W-CDMA implementations, UMTS uses a pair of 5 MHz channels, one in the 1900 MHz range for uplink and one in the 2100 MHz range for downlink. 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 have not allocated new frequencies specifically for UMTS (such as the United States).
The specific frequency bands originally defined by the UMTS standard are 1885-2025 MHz for uplink and 2110-2200 MHz for downlink.
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 Generic Radio Access Network (GRAN). It can be connected to various backbone networks like the Internet, ISDN, GSM or to a UMTS network. GRAN 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.
Interoperatibility and global roaming
At the air interface level, UMTS itself is incompatible with GSM. UMTS phones sold in Europe (as of 2004) are UMTS/GSM dual-mode phones, hence they can also make and receive calls on regular GSM networks. If a UMTS customer travels to an area without UMTS coverage, a UMTS phone will automatically switch to GSM (roaming charges may apply). If the customer travels outside of UMTS coverage during a call, the call will be transparently handed off to available GSM coverage.
Regular GSM phones cannot be used on the UMTS networks.
Vodafone Japan (former J-Phone) has a 3G network which uses W-CDMA technology and is compatible with UMTS. However, when Vodafone acquired J-Phone, Vodafone dramatically reduced the investments planned in UMTS infrastructure, so that, subscriber numbers of Vodafone Japan's UMTS network used to remain low, and 3G coverage of Japan was once incomplete. Now Vodafone Japan claims that more than 99% of the populated area is covered by 3G network, and 15% of its subscribers are 3G users as of the end of 2005.
NTT DoCoMo's 3G network, FOMA, was the first commercial network using W-CDMA since 2002. The first W-CDMA version used by NTT DoCoMo was incompatible with the UMTS standard at the radio level, however USIM cards used by FOMA phones are compatible with GSM phones, so that USIM card based roaming is possible from Japan to GSM areas without any problem. Today the NTT DoCoMo network - as well as all the W-CDMA networks in the world - use the standard version of UMTS, allowing potential global roaming. Whether and under which conditions roaming can actually be used by subscribers depends on the commercial agreements between operators.
All UMTS/GSM dual-mode phones should accept existing GSM SIM cards. Sometimes, you are allowed to roam on UMTS networks using GSM SIM cards from the same provider.
In the United States, UMTS will initially be offered (by Cingular, formerly AT&T Wireless) on the 1900 MHz spectrum only, due to existing limitation of spectrum allocated in the United States. UMTS phones designated for the US will likely not be operable overseas and vice versa; this mirrors the current situation of GSM phones and GSM networks in the US using different frequencies from those used in the rest of the world. However, the FCC has made reasonable promises to free up additional spectrum in the 2100 MHz band and most UMTS licensees seem to consider ubiquituous, transparent global roaming an important issue.
Although roaming is possible between compatible European and Asian networks, there is still no roaming possible with the United States (as of December 2004).
Spectrum allocation
Over 120 licenses have already been awarded to operators worldwide (as of December 2004), specifying W-CDMA radio access technology that builds on GSM. With the technology still emerging, politicians hurriedly set up license auctions, which funneled billions of dollars in license fees into public budgets. In Germany alone, license holders paid a total 50.8 billion euros. Operators are expected to begin gaining income from those licenses in 2005. These huge license fees have the character of a very large tax paid on income expected 10 years down the road, created huge losses, and put many European telecom operators close to bankruptcy. Over the last few years these losses have been written off, and the associated debt has been reduced, largely through income from SMS data services.
The UMTS spectrum allocated by ITU 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 are trying to free up the 2100 MHz range for 3G services, though UMTS in North America will still have to share spectrum with existing 2G services in the 1900 MHz band. 2G GSM services elsewhere use 900 MHz and 1800 MHz and therefore do not share any spectrum with planned UMTS services.
Until regulators allocate new spectrum specifically for 3G, there will be no firm answer to what frequencies UMTS will operate on in North America. 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. Initial rollout of UMTS in Canada will also be handled exclusively by the 1900 MHz band.
Other competing standards
There are other competing 3G standards, such as CDMA2000 and systems including iBurst from Arraycom, Flarion and wCDMA-TDD (IPWireless).
Both CDMA2000 and W-CDMA are accepted by ITU as part of the IMT-2000 family of 3G standards, in addition to Enhanced Data Rates for Global Evolution (EDGE) and China's own 3G standard, TD-SCDMA.
CDMA2000, being an evolutionary upgrade to cdmaOne, does not require new spectrum allocation and will operate comfortably in existing PCS spectrums.
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, Cingular 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. 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 of the rollout problems operators faced included:
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;
initially poor coverage due to the time it takes to build a network;
for fully fledged UMTS incorporating Video on Demand features, one base station needs to be set up every 1–1.5 km. While this is economically feasible in urban areas, it is impossible in less populated suburban and rural areas;
competition for broadband access from Wi-Fi;
lack of significant consumer demand for 3G
将本文加入收藏夹
新闻详情
