3G科普之综述

3G
维基百科，自由的百科全书

第三代移动通讯技术（英语：3rd-generation，3G），是指以UMTS和CDMA2000为代表的，支持高速数据传输的蜂窝移动通讯技术。3G服务能够同时传送声音﹙通话﹚及数据信息﹙电子邮件、即时通讯等﹚。3G的代表特征是提供高速数据业务，速率一般在几百kbps以上。

3G规范是由国际电信联盟（ITU）所制定的IMT-2000规范的最终发展结果。原先制定的3G远景：是能够以此规范达到全球通信系统的标准化。但目前3G存在三种标准，UMTS, CDMA2000, TD-SCDMA。

3G的含义
3G能将无线通信与国际互联网等多媒体通信结合的新一代移动通信系统。能够处理图像、音乐、视频形式，提供网页浏览、电话会议、电子商务信息服务。无线网络必须能够支持不同的数据传输速度，也就是说在室内、室外和行车的环境中能够分别支持至少2Mbps、384kbps以及144kbps的传输速度。

UMTS
UMTS的全名是Universal Mobile Telephone System，中文译为全球移动通讯系统，是基于W-CDMA科技所发展出来的。用在以GSM为主流，要进化到3G的地区，例如欧洲。UMTS目前由3GPP组织负责标准化规范的制定。3GPP所负责的2G或2.5G规范有GSM, GPRS 和EDGE。

FOMA
由日本最大的电信系统商Ntt DoCoMo在2001年提出的规范名称，一般来说就是最早的3G规范。一样基于W-CDMA的规范发展原理，它却与UMTS不兼容。目前正在开发互相兼容的补救方法。

CDMA2000
CDMA2000是3G规范中最重要也是最早开发的规范，它由2G系统中的IS-95规范演化而来，并与之存在相当程度的兼容。CDMA2000主要应用于中国、美洲、日本和韩国。目前由3GPP2组织负责制定规范标准。3GPP2组织与UMT规范中3GPP组织是互相独立的。

TD-SCDMA
向ITU提交的第三种3G方案，获得ITU通过。2004年12月西门子宣布与中国的华为技术有限公司成立合资公司TDTech，就是开发此系统的技术公司。
TD-SCDMA实验网络已建成，网络支撑的各种业务也在试验中，据中国信息产业部公报，2005年该项目组获得较大突破，预计2006年能够在中国正式开通。
当前的研发状态还不是很明朗。主要参与企业为中国的大唐电信、中兴电子、华为。其中大唐电子主要负责终端和交换设备研发。其他两家在此标准上也投入很大资金，专注于基站设备和交换设备研发。

3G与科技泡沫
欧洲3G执照和无线电频谱的拍卖在1990年代3G与科技泡沫事件中扮演了重要的角色。由于确信3G的采纳与普及会相当快速，欧洲的电信公司总计投入了3000亿欧元在标准化规范、购买设备与拓展市场上面。
但预期获利却无法使3G的普及具体化。于是研发者留下了负债和几近无用的3G执照就离开了。许多公司放弃了执照和研发计划、以降低负债。有些公司还试图与发放执照的政府打官司。

德国和奥地利运营商的一些历史数据

* 采用3G标准: WCDMA
* 可用频率:

1. 1.900 MHz – 1.920 MHz (TDD)
2. 1.920 MHz – 1.980 MHz (FDD-上行链路)
3. 2.020 MHz – 2.025 MHz (TDD)
4. 2.110 MHz – 2.170 MHz (FDD-下行链路)

* 通道带宽: 5 MHz
* 片速 : 3,84 Mcps
* Nutzertrennung: 编码(CDMA); 频率(FDMA)
* 移动终端最大发射功率: 0.125–0.25 瓦 (GSM: 1–2瓦)

在德国以下6个可用FDD－频带被发给以下运营商:

运营商 上行链路 下行链路 当时价格
沃达丰德国 D2 1.920,3 MHz – 1.930,2 MHz 2.110,3 MHz – 2.120,2 MHz 164.7亿德国马克 (84.2亿欧元)
未知 1.930,2 MHz – 1.940,1 MHz 2.120,2 MHz – 2.130,1 MHz (164.5亿马克给3G工作组, 后来返还)
E-Plus 1.940,1 MHz – 1.950,0 MHz 2.130,1 MHz – 2.140,0 MHz 164.2亿马克 (83.9亿欧元)
未知 1.950,0 MHz – 1.959,9 MHz 2.140,0 MHz – 2.149,9 MHz (163.7亿马克 给Mobilcom)
O₂－DE 1.959,9 MHz – 1.969,8 MHz 2.149,9 MHz – 2.159,8 MHz 165.2亿马克 (84.5亿欧元)
T-Mobile D1 1.969,8 MHz – 1.979,7 MHz 2.159,8 MHz – 2.169,7 MHz 165.8亿马克(84.8亿欧元)

每个频带有2个信道带宽。中间频率由运营商自定,至少要有4个200KHz分配。除此之外还要预留保护带防止信道干扰。
部署3G的国家

目前已拥有商用3G网络的国家(和地区)和使用标准为：

* 阿根廷 (CDMA2000 1x)
* 澳大利亚 (W-CDMA) (CDMA2000 1x, EVDO)
* 奥地利 (W-CDMA)
* 阿塞拜疆 (CDMA2000 1x)
* 白俄罗斯 (CDMA2000 1x)
* 百慕大群岛 (CDMA2000 1x)
* 巴西 (CDMA2000 1x)
* 加拿大 (CDMA2000 1x)
* 智利 (CDMA2000 1x)
* 中国 (CDMA2000 1x : 中国联通) 未取得牌照
* 中国（WCDMA 中国移动）未取得牌照
* 哥伦比亚 (CDMA2000 1x)
* 丹麦 (W-CDMA)
* 多米尼加共和国(CDMA2000 1x)
* 厄瓜多尔 (CDMA2000 1x)
* 格鲁吉亚 (CDMA2000 1x)
* 德国 (W-CDMA)T-Mobile、沃达丰 O2-DE ePlus
* 希腊 (W-CDMA)
* 危地马拉(CDMA2000 1x)
* 中国香港(W-CDMA)
* 印度 (CDMA2000 1x)
* 印尼 (CDMA2000 1x)
* 以色列 (W-CDMA)
* 意大利 (W-CDMA)
* 牙买加(CDMA2000 1x)
* 日本 (W-CDMA, CDMA2000 1x)
* 哈萨克斯坦(CDMA2000 1x)
* 韩国 (CDMA2000 1x) (W-CDMA in testing)
* 吉尔吉斯斯坦(CDMA2000 1x)
* 马来西亚(W-CDMA) 明讯, Celcom, MiTV, TimeCell)
* 墨西哥 (CDMA2000 1x)
* 摩尔多瓦(CDMA2000 1x)
* 荷兰(W-CDMA)
* 新西兰(CDMA2000 1x) (W-CDMA in testing)
* 尼加拉瓜(CDMA2000 1x)
* 尼日利亚 (CDMA2000 1x)
* 挪威 (W-CDMA)
* 巴基斯坦(CDMA2000 1x)
* 巴拿马(CDMA2000 1x)
* 秘鲁 (CDMA2000 1x)
* 波兰(CDMA2000 1x)
* 罗马尼亚(CDMA2000 1x)
* 俄罗斯(CDMA2000 1x)
* 斯罗文尼亚(W-CDMA)
* 韩国 (CDMA2000 1x)
* 南非 (W-CDMA in testing)
* 西班牙 (W-CDMA)
* 瑞士 (W-CDMA)
* 台湾 (CDMA2000 1x : 亚太电信) (W-CDMA : 中华电信、台湾大哥大、威宝电信、远传电信)
* 泰国 (CDMA2000 1x)
* 阿拉伯联合酋长国 (W-CDMA)
* 英国 (W-CDMA)
* 美国 (CDMA2000 1x) (W-CDMA in testing)
* 乌兹别克斯坦(CDMA2000 1x)
* 委内瑞拉(CDMA2000 1x)
* 越南 (CDMA2000 1x)

3G
From Wikipedia, the free encyclopedia

3G (or 3-G) is short for third-generation technology. It is used in the context of mobile phone standards. The services associated with 3G provide the ability to transfer simultaneously both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instant messaging). In marketing 3G services, video telephony has often been used as the killer application for 3G.

3G networks are not upgrades of 2G networks and do not operate on the same frequency spectrum; rather, entirely new networks need to be built and new frequencies need to be assigned to mobile operators. Induced euphoria led to huge spectrum-licensing fees in many countries, especially in Europe, where spectrum auctions went into the billions of euros. These spectrum licensing fees which were collected years before actual 3G development, together with the enormous investments necessary to build the all-new 3G networks, financially strained a number of mobile operators, delaying 3G roll-out worldwide except in Japan and South Korea, where such spectrum licensing fees were non-existent as the priority in those countries was set on national IT infrastructure development.

The first country which introduced 3G on a large commercial scale was Japan. In 2005, about 40% of subscribers used 3G networks only, with 2G being on the way out in Japan. It was expected that during 2006 the transition from 2G to 3G would be largely completed in Japan, and upgrades to the next 3.5G stage with 3 Mbit/s data rates were underway.

The successful 3G introduction in Japan showed that video telephony was not the killer application for 3G networks after all. The real-life usage of video telephony on 3G networks was found to be a small fraction of all services. On the other hand, downloading of music found strong acceptance by customers. Music download services in Japan were pioneered by KDDI with the EZchakuuta and Chaku Uta Full services.

Technically, 3G networks are not IEEE 802.11 networks. IEEE 802.11 networks are short range, primarily internet access networks, while 3G networks are wide area cellular telephone networks which evolved to incorporate high-speed internet access and video telephony to these networks.

Background

It is estimated that there are about 60 3G networks in 25 countries around the world. In Asia, Europe and the USA, telecommunication companies use WCDMA technology with the support of around 100 terminal designs to operate 3G mobile networks.

In 2001, NTT DoCoMo - one of the giant telecommunication companies in Japan - was the first telecommunication company to launch a commercial WCDMA network. The introduction of 3G services within Europe began in early 2003.

The official 3G mobile network is the systems and services based on the ITU family of standards under the International Mobile Telecommunications programme, 'IMT-2000'. A boost was given to 3G mobile networks in Europe when the EU council suggested that the 3G operators should cover 80% of the European national populations by the end of 2005.

Features

The most significant features offered by third generation (3G) mobile technologies are the momentous capacity and broadband capabilities to support greater numbers of voice and data customers - especially in urban centres - plus higher data rates at lower incremental cost than 2G.

By using the radio spectrum in bands identified, which is provided by the ITU for Third Generation IMT-2000 mobile services, it subsequently licensed to operators. 3G uses 5 MHz channel carrier width to deliver significantly higher data rates and increased capacity compared with 2G networks.

The 5 MHz channel carrier provides optimum use of radio resources for operators who have been granted large, contiguous blocks of spectrum. On the other hand, it also helps to reduce the cost to 3G networks while being capable of providing extremely high-speed data transmission to users.

It also allows the transmission of 384kbps for mobile systems and 2Mbps for stationary systems. 3G users are expected to have greater capacity and improved spectrum efficiency, which will allow them to access global roaming between different 3G networkings.

Standard 3G

International Telecommunications Unit (ITU): IMT-2000 consists of five radio interfaces

* W-CDMA
* CDMA2000
* CDMA2001
* TD-CDMA / TD-SCDMA
* UWC-136
* DECT+

Issues

Even though 3G has successfully been introduced to European mobile users, there are some issues that are debated by 3G providers and users.

* High input fees for the 3G service licenses;
* Great differences in the licensing terms;
* Current high debt of many telecommunication companies, making it more of a challenge to build the necessary infrastructure for 3G;
* Member State support to the financially troubled operators;
* Health aspects of the effects of electromagnetic waves;
* Expense and bulk of 3G phones;
* Lack of 2G mobile user buy-in for 3G wireless service;
* Lack of coverage because it is still new service;
* High prices of 3G mobile services in some countries.