Analysis of 3G standards and services
第三代移动通信系统(3G)的标准及其业务分析
北方交通大学 运输自动化与通信实验室 赵晓红
北方交通大学现代通信研究所 杨涛
Abstract: Wireless mobile communication system has developed from analog system to current digital system. With big increase of demand on communication business type and quantity, 2G mobile communication system with business modes limited to voice and low rate data can not satisfy the demand any more, large-capacity, high-speed, full-scale 3G comes out. This paper mainly introduces standardization of 3G and also makes analysis of its main business modes.
Key words: 3G, RTT, wireless access network
摘要：无线移动通信系统已经由第一代模拟系统发展到了现在的第二代数字系统，随着对通
信业务种类和数量需求的剧增，业务类型主要限于语音和低速数据的第二代移动通信系统已
不能满足需要，大容量、高速率、全方位的第三代移动通信系统（3G）应运而生。本文主要
介绍了3G的标准化过程，并对其主要业务类型进行了分析。
关键字：第三代移动通信系统 无线传输提案(RTT) 无线接入网
一、3G介绍
经过六七十年的发展,通信系统,已经从最初的专用网发展到现在可以覆盖全球大部分地区的
公用网；已经从最初的大区制网络结构发展到现在的蜂窝小区网络结构；已经从最初的模拟
网络发展到现在的数字网络公用网。通信系统经过第一、二代的发展,已经进入了向第三代转
化的过程。随着通信业务的迅猛发展,通信量的激增,现有的第二代移动通信系统在支持全球
漫游、频谱利用率以及数据业务方面都表现出了一定的不足,尽管GSM的Phase 2＋支持较高的
数据传输速率,但这只是对第二代移动通信技术的补缀,并且以牺牲其他用户的利益为代价,对
系统用户并不有利。第三代移动通信技术（3G）应运而生,3G使通信世界朝着媒体集中、行业
合并的方向迈进,互联网、IP技术和移动通信即将融为一体。第三代移动互联网技术的飞速发
展必然带来各方面重大的变革：
◆人们将不只是用耳朵听而更多的用眼睛看,眼睛将成为人们从3G中获取信息与知识的主要工
具。
◆3G中数据（“非语音”）业务将与传统的语音业务截然不同。
◆移动通信在容量上将与固定通信相当,很多人将只拥有一部移动电话。
◆移动电话将成为人们生活中必不缺少的一部分。它将成为引导人们生活的核心。它可以实
现人们任何地点、任何时间与任何人进行通信的梦想。
◆3G是建立在码分多址(CDMA)的基础之上,这与2G中广泛采用的时分多址(TDMA)不同。
◆美国、日本和欧洲的移动通信商家都有自己的技术,现在统一为一个标准,各自独立的无线
发展道路及欧洲无线的领导地位因而受到了挑战。
二、3G的标准
2.1 3G的标准化进程
早在1985年,国际电信联盟（ITU）就提出了第三代移动通信的概念,当时称为未来公用陆地移
动通信系统（FPLMTS）,1996年改为IMT-2000。由于移动通信在未来的信息产业中的重要作用,
各国的政府部门、电信运营商及制造商均积极的参与有关第三代移动通信标准的制定工作。
截至1998年9月,16个无线传输技术（RTT）的提案被提交：除6个卫星接口方案外,地面无线接
口方案有10个,主要分为两大类：CDMA与TDMA,其中CDMA占据主导地位。这几项技术涵盖了欧
洲的W－CDMA、美国的cdma2000和我国的TD－SCDMA等制式,焦点主要集中在W－CDMA和cdma2000上。
2.2 3GPP
1998年10月,第三代伙伴计划（3GPP）出台,该标准化组织由欧洲的ETSI、中国的CWTS、日本
ARIB、韩国TTA和美国的T1等组成,宗旨是制定以GSM为核心网,UTRA为无线接口的标准。1999
年1月,3GPP2正式成立,该组织包括美国的TIA、中国的CWTS、日本ARIB、韩国TTA等,宗旨是制
定以ANSI/IS-41为核心网,cdma2000、WUC136 为无线接口的标准。世界上各大标准制定组织
间空前的合作大大加速了第三代移动通信系统的标准化进程。1999年上半年, 全球IMT-2000
标准取得很大进展,该标准能够满足不同技术实体棗GSM、CDMA及TDMA在政治和商业上的要求。
2.3 空中接口模式
第三代移动通信网的IMT-2000标准是一种基于CDMA的标准,该标准包含三种任意的操作模式,
每一种模式都能通过GSM MAP和IS-41网络结构进行工作。这三种模式是：
三种操作模式,一种针对欧洲和亚洲。一种针对日本,另一种针对美国,与原有的2G的模式有
一些相似,主要的变动是日本已加入了欧洲的GSM共同体,采用了WCDMA。
事实上严格得讲,如果把DECT (IMT FT) 和 EDGE (IMT SC 或 IWC 136)包括在内的话,最终
的IMT-2000的ITU提案包括五种地面无线接入标准。
三种无线接入模式中主要的核心网络标准有两种（现有）：GSM MAP和TIA IS-41（通信联盟,
英国的标准制定组织）。在移动通信网中,核心网是无线接入网所要连接的网络设备。无线接
入网是移动通信网的一部分,用来处理用户接入包括无线基站和其它节点的接入问题。
2.4 3G的数据传输速率
国际电信联盟（ITU）已经提出了IMT-2000标准必须支持的最低的数据传输速率。这要根据正
在进行的呼叫的移动性来定义。即3G所能支持的数据传输速率取决于呼叫所发生的环境。
高移动性:当3G用户在郊区室外以120公里每小时的速度移动时,采用144kbps的数据传输速率。
完全移动性:当步行者在郊区室外以低于120公里每小时的速度移动时,数据传输速率可以达到
384kbps。
受限移动性:在低移动性的固定的室内及小范围的室外环境,数据传输速率至少能达到2Mbps。
三、3G具体业务
3G的宽频带可以提供很多方面的业务,主要包括：
3.1 音频
通常,利用各种不同的压缩算法如微软或Real网的算法或MPEG-1音频第三层（MP3）协议,音频
或视频可以通过互联网下载（传输、存储或播放）或实时播放。有了3G,MP3文件就可以通过一
个专门的服务器从空中直接下载到你的电话中。
从互联网通过固定的长途电话和电缆下载多媒体到PC机很大程度上依赖于带宽,因为图像和有
效服务的质量与可用带宽成反比。目前,由于带宽的限制,用户只能通过固定的网络先上网,将
文件下载到自己的便携设备,随后再观看和收听,通过移动通信网还得不到实时的音频和视频。
因为即使是很短的声音片断都会占用很大的空间。
对于需要高速的移动数据的移动音频业务,带宽越宽越好棗这正是3G对于移动多媒体如移动音
频和视频的魅力所在。预计在未来的四年中将会出现移动电话和日常消费品的融合,到那时我
们将能够通过下一代移动设备在任意的时间,任意的地点获得有关声音、互联网或音乐的数据。
3.2 通过互联网协议传送声音
3G在音频方面另一项业务就是VoIP（Voice over IP）能够通过互联网向全世界任意地点发送
呼叫,而价格与本地呼叫相同的一项业务。随着3G及更高速率的2.5G 技术如EDGE、 VoIP的发
展,VoIP将第一次应用于移动电话。在一次呼叫中,VoIP可以作为一种常规业务。
由于VoIP需要很宽的带宽,因此为了减小IP干线延迟和掉包的可能性,通常需要非常高的切换
速率。另外,VoIP与标准的语音业务可以同时存在。
3.3 静态图像
静态图像如照片、图画、信函、明信片、贺卡、演示文稿和静态网页可以象通过固定电话网
传送一样通过移动通信网进行发送和接收。
带宽和时间这两种影响因素是成反比的。带宽越宽,传送图片所需的时间越短,反之亦然。这
就是为什么直到现在图像的传送才成为一种广泛流行的非语音移动业务,因为在引入移动数据
包之前,特定的低数据传输速率需要花费太长的时间。
图片文件的大小取决于图形的分辨率和压缩的形式。典型的每幅JPEG格式的图片大小为50K至
100K,用移动数据包可以迅速的传送,进行几乎实时的发布。
3.4 移动图像
在移动环境下发送移动图像有几种情况：监视停车场或建筑物的入侵者或窃贼,从救护车向医
院传送病人的图片及视频会议等。
移动图像的传送是GPRS和3G终端的一项业务,也许它可以支持更高的数据传输速率,但通过微
软的Netmeeting召开一次视频会议,即使1M字节的数据,传送的视频图像都达不到平滑。或许
改进的压缩技术可以使得通过64kbps的带宽传送的视频图像的质量还可以让人接受。
3G的目标就是：进一步提高带宽,通过移动通信网进行高质量图像的传送。将所有的移动视频
和图像传送业务移植到3G载体中。到那时,所有这些过程都可以从互联网站上下载。
3.5 虚拟本地环境
环球移动电话业务（UMTS）又称为虚拟本地环境（VHE）,即实现用户的无缝接入,在任何地方
接受不论来自家庭、办公室或运动中的信息感觉都象是在本地。VHE针对的主要是漫游用户
（全部移动电话用户的一小部分）。
如果将VHE的全球一致性模块（UIM）放入任意的终端设备,VHE还能进行其它更有用的业务。
而如果智能卡能够获得更广泛的支持,这些终端设备还可以不是移动设备。
虽然在切换设备中（用户可能拥有多个不同构造的3G设备）和非移动业务如身份鉴定和移动
银行中,智能卡也非常有用,但它们的存储容量非常有限,随着电子邮件和其它的业务在全球
得到广泛的应用,互联网越来越普及,无论有没有智能卡,通过任意的浏览器都可以访问互联
网业务。
3.6电子代理
电子代理在未来的移动通信中将发挥重要的作用,它主要用来进行网上搜索并将结果汇报给
用户,这是一种处理移动业务的有效方式。
当然,3G设备将比今天的移动电话更多的融入人们的生活。它们可以作为电子助手、电子秘
书、电子顾问和电子管理员。或许,十年内,我们的移动设备就可以喊我们起床、帮我们阅读
电子邮件、预定食品、告诉我们最好的工作路线、提醒我们开会。这其中的关键问题是这些
过程人为或计算机产生并控制的程度及这些设备能够“学习”我们的个人喜好并做出相应的
处理的程度。
3.7 下载软件
21世纪,软件将越来越多的从网上下载而不是购买包装的产品。文件传输业务也是这样。例
如,如果你需要WinZip 或 Abode Acrobat用以阅读文件,你就可以从3G网络下载到你的3G终
端设备。
下载时间取决于你的调制解调器的速度和要下载软件的大小。
各类业务的最佳载体
以下列出了各类业务的最佳载体：
四、结论
第三代移动通信必将为移动多媒体带来高速的数据传输带宽、完善的移动终端和各种新的
业务,为通信注入新的活力。从各方面考虑,第二代移动通信系统将在较长时间内与第三代
系统共存。我国拥有世界上最大的移动通信市场,抓住机遇,发展我国电信事业,实现第二
代系统向第三代系统的平稳过渡,是现在值得关注和积极研究的重要问题。
参考文献：
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[2] 谈振辉,韩晓斌等.IMT－2000的网络结构相关规定及关键技术,电信科学,1998(10)：7～11.
[3] 顾琰,孙峻岭,沈连丰.第三代移动通信系统及其关键技术,通讯世界,1998(11)：31～33.
[5] 马霓 韦岗等.IMT2000的研究进展,移动通信,2000（1）：19～22.
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1. Introduction to 3G
After the development of more than to years, communication system has developed from original private network to current public network covering most districts of the whole world; from original parent zone network construction to current cellular one; and from analog network to digitae public network. After 1G and 2G developments, communication system has entered process of transition from 2G to 3G. With huge progress of communication service and rapid increase of communication quantity, current 2G shows shortage in supporting global roaming, frequency spectrum usage rate and digitae . Though GSM抯 Phrase 2+ supports higher data transmission rate, it is only complementary to 2G and is based on sacrifice of other subscribers?benefit and is not good to system subscribers. 3G comes out in this situation. 3G make communication world towards media integration and fields incorporation and Internet, IP technology and mobile communication will be integrated. The rapid development of 3G mobile Internet will inevitably bring important revolutions in each respect.
◇People will more use eyes more often instead of ears. Eyes will become a main tool to get information and knowledge from 3G.
◇Data service of 3G (non voice) will be totally different from traditional voice service.
◇Mobile communication will be the same as fixed one in capacity and most people will only own one mobile phone.
◇Mobile phone will be an inevitable part of people. It will be the core to lead people抯 life. It can help to realize the dream to communicate with others wherever, whenever and whoever.
◇3G is based on CDMA while 2G on TDMA which is widely used.
◇Mobile communication vendors in America, Japan and Europe have their own technologies but now they have been unified to one standard. So independent wireless development road and leading position of Europe wireless are in challenge.
2. 3G standard
2.1 3G standardization process
Early in 1985, ITU has brought the concept of 3G mobile communications which is called Future Public Land Mobile Telecom System (FPLMTS), and it is changed as IMT-2000 in 1996. Because of the important function of mobile communication in future information industry, government, telecom operators as well as manufacturers in each country are all active to participate the making of 3G standard. Till September 1998, 16 RTTs proposals are presented: Except from 6 satellite interface solutions, there are 10 ground wireless interface solutions and are mainly divided into two types: CDMA and TDMA. Among them, CDMA is in a leading place. These technologies cover W-CDMA in Europe, cdma2000 in America and TD-SCDMA in our country but the focus is W-CDMA and cdma2000.
2.2 3GPP
In October 1998, 3G partnership plan (3GPP) is released. This standard organization is comprised of ETSI in Europe, CWTI in China, ARIB in Japan, TTA in Korea and TI in America. Its aim is to maked out standard with GSM as core network and UTRA as wireless interface. In January 1999, 3GPP2 is officially set up and this organization includes TIA in America, CWTS in China, ARIB in Japan and TTA in Korea etc. Its aim is set set up standard with ANSI/IS-41 as core network, cdma2000, WUCI36 as wireless interface. The cooperation spirit ameng standard organizations in the world greatly accelerates standardization process of 3G. In the first half of year 1999, global IMT-2000 standard gets great progress and this standard can satisfy demands of different technical entities---GSM, CDMA and TDMA in politics and commerce.
2.3 Air interface mode
IMT-2000 in 3G is a standard based on CDMA. This standard includes three free operation modes and each mode can operate through GSM-MPA and IS-41 network construction. The three modes are:
In three operation modes, one is for Europe and Asia, one for Japan and the third for America. A little similar to original 2G mode, a major change is that Japan has entered GSM union of Europe and adopted WCDMA.
Strictly speaking, if including DECT (IMT FT) and EDGE (IMT SC or IWC 136), final IMT-2000抯 ITU proposal includes five ground wireless access standards.
There are two (current) main core network standards in three wireless access modes: GSM MAP and TIA IS-41 (communication United, standard organization in Britain). In mobile communication network, core network is service that wireless access network need to connect. Wireless access network is part of mobile communication network and is used to handle subscribers access problems concerning wireless base stations and other nodes.
2.4 3G data transmission rate
ITU has brought out the lowest data transmission rate that IMT-2000 standard must support. This should define according to the mobility of ongoing calling. That is, the data transmission rate that 3G could support depends on the environment which call happens.
High mobility: When 3G subscribers moves with 120km/h outdoors, 144kbps rate transmission rate is adopted.
Complete mobility: When walkers move outdoors at a speed lower than 120km/h, data transmission rate could reach 384kbps.
Limited mobility: In the environment of fixed indoors place and small zone outdoors with low mobility, data transmission rate can reach at least 2Mbps.
3 .3G services
3G broad frequency band may provide services in many respects which include:
3.1 Voice frequency
Usually, with all kinds of compression algorithms like Microsoft or algorithm of Real network or MP3 protocol of MPEG-1, audio or video can download through Internet (transmission, restore or broadcasting) or real time broadcast. With 3G, MP3 documents may directly download through a dedicated server from air to your phone.
It greatly depends on bandwidth to download multimedia from Internet through fixed long distance phone and cable to PC, because image and quality of effective service are in converse ratio with available bandwidth. At present, because of limit of bandwidth, users can only be online through fixed network and download documents to their own portable devices, then watch and listen. Users cannot get real time audio and video through mobile communication network since very short voice segment will take a lot of space.
To mobile audio service which needs high-speed mobile data, the broader of the bandwidth, the better桾his is just the charming point of 3G to mobile media like mobile audio and video. It is estimated that in the coming four years, mobile phone will emerge with daily consumption. At that time, we will be able to obtain data about voice, Internet and music through next generation mobile device at any time and any place.
3.2 Transmitting voice through Internet protocol
Another service of 3G in audio is VoIP (Voice over IP)---can send calls through Internet to anywhere in the world while the price is the same as local ones. With the development of 3G and higher rate 2.5G technology like EDGE, VoIP, VoIP will be used in mobile phone at first time. In a call, VoIP can be used as a regular service.
3.3 Static images
Static images like pictures, drawings, letters, postcards, greeting cards, demonstration files and static websites can be sent and received through mobile communication network as through fixed phone network.
Bandwidth is in converse ratio with time. Broader bandwidth needs shorter time to transport picture and it is the same with contrary condition. This is the reason why picture transmission becomes a popular non-voice mobile service until now. Before import of mobile packet, data transmission of specific low rate needs a lot of time.
The size of picture documents depends on resolution of picture and format of compression. The size of typical JPEG format is 50K to 100K. It can make fast transpontation with mobile packet, almost real time release.
3.4 Mobile images
There are several conditions to send mobile images in mobile condition: Monitoring invader or burglar in parking lot or building, transmitting picture of patient and video from ambulance to hospital.
The transmission of mobile image is a service of GPRS and 3G terminals but it may support higher data transmission rate. But through Microsoft抯 Netmeeting to hold a video conference, even using 1M byte data, the transported video image can not reach smoothly. Maybe enhanced compression technology will make quality of video image transported through 64kbps bandwidth acceptable.
The aim of 3G is: further increasing bandwidth and transmitting high quality image through mobile communication network. Transplanting all mobile video and image to 3G carriers. At that time, all these process will be downloaded from Internet.
3.5 Virtual home environment
Universal mobile telephone service (UMTS) is also called virtual home environment (VHE). That means seamless access of users and users will feel just like home when they receive information at anywhere from home, office or in moving state. VHE is mainly facing roaming users (a small part of whole mobile users).
If the UIM of VHE is put in any terminal device, VHE can also perform other useful services. If intelligent card could obtain wider support, these terminal devices can even be non-mobile devices.
Though in switch devices (users could own many 3G devices with different constructions) and non-mobile service like identity certification and mobile bank, intelligent card is also very useful, but their storage capacity is very limited. With wider application of e-mail and other services, Internet is getting more and more popular. With or without intelligent card, users can visit Internet service through any browsers.
3.6 Electronic agency
Electronic agency will play an import role in future mobile communication. It is mainly used to make network search and report result to users. This is an effective way to handle mobile service.
Certainly, 3G devices will emerge into people抯 life deeper than current mobile phone. It can act as electronic assistant, electronic secretary, electronic consultant and electronic manager. Maybe in ten years, our mobile device will wake us up, help to read e-mail, reserving food, telling us best working path and alarming us for conference. The key problem is that these devices can 搇earn?our personal interest thus make out proposal accordingly.
3.7 Downloading software
In 21st century, software will download from network instead of purchasing packed products.
Documents transmission service is the same. For example, If you need WinZip or Abode Acrobat to read file, you can download from 3G network to your 3G terminal device.
Download time depends on rate of your modem and size of the so ftware to be downloaded .
Best carriers of all kinds of services
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The following gives best carrier of all kinds of services:
4.Conclusions
3G will inevitably bring mobile multimedia with high-speed data transmission bandwidth, complete mobile terminal and all kinds of new service and put new energy in communication. Considering from all respects, 2G will coexist with 3G for a long time. We owns biggest mobile communication market in the world. It is very important to catch opportunities and develop our communication to realize smooth transition from 2G to 3G.
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