通信工程毕业设计外文翻译--下一代无线宽带的目标(4G—5G)

附录

一、英文原文：

Goals Of True Broad band’s Wireless Next Wave

(4G-5G)

K.R.Santhi,Prof.V.K.Srivastava,G.SenthilKumaran,Eng. Albert Butare.Kigali Institute of Science Technology and Management (KIST),B.P.3900, Kigali,

Rwanda.

Abstract

As access technology increases, voice, video,multimedia, and broadband data services are becomingintegrated into the same network. Fourth Generation (4G)is the next generation of wireless networks that will replacethird Generation (3G) networks sometimes in future. 4G isintended to provide high speed, high capacity, low cost perbit, IP based services.4G is all about an integrated, globalnetwork that’s based on an open system approach. The goalof 4G i s to “replace the current proliferation of core cellularnetworks with a single worldwide cellular core networkstandard based on IP for control, video, packet data andV oIP. But while 3G haven’t quite arrived, researchers wantto contribute their ideas to the development of an as-yetundefined "wireless world" that could become operationalby around 2010. This paper deals with the fundamentalsand issues of networks, technologies, spectrum, standards,terminals, services of 4G and about the visions that thenetwork operators and service providers see for theevolution of 4G mobile systems and where is future researchfrom their perspective necessary?

Keywords：Wireless, 4G, W-OFDM, MC-CDMA, LAS-CDMA,UWB.

I. INTRODUCTION

While carriers and handset manufacturers obviously havetheir hands full with 3G, some companies are alreadylooking beyond this next generation of wirelesstechnology and networks. 4G is simply an initiative byacademic R&D labs to move beyond the limitations andproblems of 3G which is having trouble getting deployedand meeting its promised performance and throughput.While this 3G has not completely reached researchers andvendors are expressing growing interest in 4G why? Twomain areas are addressed in these initiatives: An increaseof capacity in the radio link and seamless mobility acrossheterogeneous access networks. Section 2 discusses aboutthe issues of 3G that has created interest towards 4Gdevelopments.

Section 3 about evolution and comparison,Section 4 describes about the goals and the vision, section5 explains about some of the technologies for 4G, and inother following sections the applications, the research andother issues for 4G developments are discussed.

II. WHY THE LEAP TOWARDS 4G?

3G networks are in a very painful phase of theirdevelopment, with early trials yielding disappointingresults, costs ballooning, technical glitches, and networkoperators being forced to deflate expectations based onunrealistic hype. Despite the hype surrounding thehigher-speed 3G mobile networks now underconstruction, the reasons for the leap towards 4G are:

A. Performance

Industry skeptics say that users will not be able to takeadvantage of rich multimedia content across wirelessnetworks with 3G. 4G communications will featureextremely high-quality video equal to that of high-definitiontelevision. In addition, it will enable wirelessdownloads at speeds exceeding 100 Mbps, about 260times than 3G wireless network.

B. Interoperability

There are multiple standards for 3G making it difficult toroam and interoperate across networks. We need a globalstandard that provides global mobility and serviceportability so that service provider would no longer bebound by single-system vendors of proprietaryequipment.

C. Networking

3G are based on primarily a wide-area concept. We needhybrid networks that utilize both wireless LAN (hot spot)concept and cell or base-station WAN design. With 4G,the world would have base stations everywhere, ensuringphone usersconnection to a high-speed networkanywhere, anytime.

D. Bandwidth

We need wider bandwidth and higher bit rates. The 4Gtechnology, with its transmission speeds of more than 20mbps, would offer high-bandwidth services within thereach of LAN "hotspots," installed in offices,homes,coffee shops,and airport lounges. Away from thesehotspots, customers could connect to souped-up 2Gnetworks for voice and rudimentary data coverage.

E. Technology

Unlike 3G, 4G will more resemble a conglomeration ofexisting technologies rather than an entirely newstandard. Analysts define 4G as a seamless combinationof existing 2G wireless networks with local-areanetworks (LANs) or Bluetooth.

F. Convergence

Convergence involves more than mere technology; it is acoming together of services and markets.We need allnetwork that utilizes IP in its fullest form with convergedvoice and data capability,which the 4G will achieve.

G. Cost

4G systems will prove far cheaper than 3G, since theycan be built atop existing networks and won't requireoperators to completely retool and won't require carriersto purchase costly extra spectrum.Also an open systemIP wireless environment would probably further reducescosts for service providers by ushering in an era of realequipment interoperability.

H. Scalability

Scalability, or the ability to handle increasing numbers ofusers and diversity of services, is more challenging withmobile networks."Design for Scalability," includesinformation that can help you meet changing usagedemands.Because an all IP core layer of 4G is easilyscalable, it is ideally suited to meet this challenge.

III.EVOLUTION AND COMPARISON OFBROADBAND

WIRELESS

1) First Generation (1G):1G wireless mobilecommunication systems, was introduced in the early1980s.1G wireless was analog and supported the firstgeneration of analog cell phones.They include asignaling protocol known as SS7 (Signaling System 7).

2) Second Generation (2G): 2G systems, fielded in thelate 1980s, were intended primarily for voicetransmission and was all about digital PCS.

3) Third Generation (3G): 3G in wireless will be adeliberate migration to faster, data-centric wirelessnetworks.The immediate goal is to raise transmissionspeeds from 125kbps to 2M bit/sec.

4) Fourth Generation (4G): In reality, as of first half of2002, 4G is a conceptual framework for or a discussionpoint to address future needs of a universal high speedwireless network that will interface with wirelinebackbone network seamlessly.

IV. THE 4G NETWORK THAT THE

CELL-HEADSDREAM ABOUT

4G can be imagined of as an integrated wireless systemthat enables seamless roaming between technologies.Auser can be operating in cellular technology network andget handed over to a satellite-based network and back to afixed wireless network, depending upon the networkcoverage and preference of charging.

A. The Goals

Open Mobile Alliance’s (OMA) main goal is to makesure different wireless services and devices worktogether, and across countries, operators, and mobileterminals.Other plans in the group's charter include:

?Deliver open standards and specifications based onmarket and customer requirements.

? Create and promote a common industry view on anarchitectural framework.

? Help consolidate standards groups and work inconjunction with other existing standardsorganizations and groups.

B. The Composite Vision

? 20 Mbps data rates

? Streaming Audio/Video

? Asymmetric Access

? Adaptive Modulation/Coding

? Dynamic packet assignment

? Smart/Adaptive antennas supported

C. 4G Network Architecture

“4G” wireless networks can be realized with an IP-basedcore network for global routing along with morecustomized local-area radio access networks that supportfeatures such as dynamic handoff and ad-hoc routing aswell as newer requirements such as self-organization,QoS, multicasting, content caching, etc..

In 4G LANs will be installed in trains and trucks as wellas buildings, or even just formed on an ad-hoc basisbetween random collections of devices that happen tocome within radio range of one other. Routing in suchnetworks will depend on new architectures, already underdevelopment by the IEEE and a European project calledMobile IP Network Developments (MIND).

D. The working Principle

In 4G-style mobile IP, each cell phone is assigned apermanent "home" IP address, along with a "care-of"address that represents its actual location.When acomputer somewhere on the Internet wants tocommunicate with the cell phone, it first sends a

packetto the phone's home address.A directory server on thehome network forwards this to the care-of address via atunnel, as in regular mobile IP. However, the directoryserver also sends a message to the computer informing itof the correct care-of address, so future packets can besent directly.This should enable TCP sessions and HTTPdownloads to be maintained as users move betweendifferent types of networks.Because of the manyaddresses and the multiple layers of subnetting, IPv6 isneeded for this type of mobility.

V. TECHNOLOGIES THAT SUPPORT 4G

The revolution in 4G will be the optical networking, thenew air interface, the portable device etc.

A. The Transmission Protocols

1) OFDM: OFDM is a digital modulation technology inwhich in one time symbol waveform, thousands oforthogonal waves are multiplexed.This is good for highbandwidth digital data transition.

2) W-OFDM: W-OFDM enables data to be encoded onmultiple high-speed radio frequencies concurrently. Thisallows for greater security, increased amounts of databeing sent, and the industry’s most efficient use ofbandwidth.W-OFDM enables the implementation of lowpower multipoint RF networks that minimize interferencewith adjacent networks.This enables independentchannels to operate within the same band allowingmultipoint networks and point-to-point backbone systemsto be overlaid in the same frequency band.

3) MC-CDMA : MC-CDMA is actually OFDM with aCDMA overlay.Similar to single-carrier CDMA systems,the users are multiplexed with orthogonal codes todistinguish users in (multi-carrier) MC-CDMA.Howeverin MC-CDMA, each user can be allocated several codes,where the data is spread in time or frequency.

4) LAS-CDMA：LinkAir Communications is developer of LAS-CDMA(Large Area Synchronized Code Division MultipleAccess) a patented 4G wireless technology. LAS-CDMAenables high-speed data and increases voice capacity andlatest innovative solution, CDD, merges the highlyspectral efficient LAS-CDMA technology with thesuperior data transmission characteristics of TDD.Thisresulting combination makes CDD the most spectrallyefficient, high-capacity duplexing system available today.

B. The Radio Interface-UWB Radio

To make 4G really work carries will need to migrate toUltra Wideband (UWB) technology.UWB radiowill deliver essential new wireless andwired bandwidth inexpensively, without using preciousand scarce radio frequencies.Instead,digital video, voiceand data are enabled using modulated pulses of energythat peacefully co-exist alongside traditionalcommunications.UWB radio solves the multipath fadingissues and is 1,000% more process efficient than CDMA.

C. The Network-LMDS

Local multipoint distribution system (LMDS) is thebroadband wireless technology used to deliver voice,data, Internet, and video services in the 25-GHz andhigher spectrum (depending on licensing).The acronymLMDS is derived from the following: L(local)—denotes that propagation characteristics ofsignals in this frequency range limit the potentialcoverage area of a single cell site;

M (multipoint)—indicates that signals are transmitted ina point-to-multipoint or broadcast method;

D (distribution)—refers to the distribution of signals,which may consist of simultaneous voice, data, Internet,and video traffic;

S (service)—implies the subscriber nature of therelationship between the operator and the customer.

VI. POTENTIAL APPLICATIONS OF 4G

1) Virtual Presence: 4G system gives mobile users a"virtual presence" -- for example, always-on connectionsthat keep people involved in business activities regardlessof whether they are on-site or off.

2)Virtual navigation:A remote database contains thegraphical representation of streets, buildings, andphysical characteristics of a large metropolis.Blocks ofthis database are transmitted in rapid sequence to avehicle, where a rendering program permits the occupantsto visualize the environment ahead.

3) Tele-medicine: 4G will support remote healthmonitoring of patients.For e.g. the paramedic assistingthe victim of traffic accident in a remote location mustaccess medical records and may need videoconferenceassistance from a surgeon for an emergency intervention.The paramedic may need to relay back to the hospital thevictim's x-rays taken locally.

4)Tele-geoprocessing applications:Thecombination of geographical information systems (GIS),global positioning systems (GPS), and high-capacitywireless mobile systems will enable a new type ofapplication referred to as tele-geoprocessing.Queriesdependent on location information of several users, inaddition to temporal aspects have many applications.

5) Crisis-management applications:Naturaldisasters can affect the entire communicationsinfrastructure is in disarray.Restoring communicationsquickly is essential.With wideband wireless mobilecommunications Internet and video services, could be setup in hours instead of days or even weeks required forrestoration of wireline communications.

6) Education :Educational opportunities availableon the internet, for individuals interested in life-longeducation, will be unavailable to client in remote areasbecause of the economic unfeasibility of providingwideband wireline internet access.4G wirelesscommunications provides a cost-effective alternative inthese situations.

VII. ROLE OF THE WIRELESS

INDUSTRYRECOMMENDATIONS

We are bringing to the attention of professionalsfollowing issues and problems that must be analyzed andresolved:

1)Standardization: Standardization of wireless networksin terms of modulation techniques, switching schemesand roaming is an absolute necessity for 4G. We mustpay more attention to general meaning advancedtechnologies.

2) Lower Price Points Only Slightly Higher thanAlternatives: The business visionaries should do someeconomic modeling before they start 4G hype. Theyshould understand that 4G data applications likestreaming video must compete with very low costwireline applications.

3) More Coordination Among Spectrum RegulatorsAround the World:We must demand almost freespectrum NOT necessarily unlicensed Spectrumregulation bodies must get involved in guiding theresearchers by indicating which frequency band might beused for 4G.

4) Regulatory frameworks:Policy and RegulatoryEnvironment which Provides Transparency, Certaintyand a Level Playing Field are necessary. The mostimportant thing is that we should recognize thatregulatory framework is as much an evolving matter astechnology, and be prepared to meet changes with anopen-minded and pragmatic attitude, always keeping theinterests of the industry and consumers in mind.

5) More Academic Research:Universities must spendmore effort in solving fundamental problems in radiocommunications (especially multiband and widebandradios, intelligent antennas and signal processing).

6) Voice-independent Business Justification Thinking:Business and Technology executives should not bias theirbusiness models by using voice channels as economicdeterminant for data applications.V oice has a built-indemand limit - data applications do not.

7) Integration Across Different Network Topologies:Network architects must base their architecture on hybridnetwork concepts thatintegrates wireless wide areanetworks, wireless LANS (IEEE 802.11a, IEEE 802.11b,IEEE 802.11g, IEEE 802.15 and IEEE 802.16), Bluetoothwith fiber-based Internet backbone.Broadband wirelessnetworks must be a part of this integrated networkarchitecture.

8) Non-disruptive Implementation: Upgrading from 3G to 4G is expected to be seamless to end-users with nodevice upgrades required.

VIII. DEVELOPMENTS IN 4G

AT&T is combining W-OFDM and EDGE technologies,to provide broadband mobile downlink access at peakrates of up to 10 Mbps while EDGE offers uplink accessat 384 Kbps with an 800KHz bandwidth in a high-mobilityenvironment.

Sun Microsystems Laboratories are building 4G wirelesstechnologies that promise tointegrate voice and web datain an IP-based mobile communications.

The Government of Karnataka in India has signed a MoUwith Charmed Technologies Inc from Beverly Hills,California and Software Technology Parks of India inKarnataka to develop 4G wireless technology. Theproject plan to use wireless technology based on theIEEE802.11a and IEEE802.11b standards for wirelessLAN for the underlying network is designed to support adata rate of up to 11Mbps and 54Mbps respectively. Thegoal is to get 6 billion people connected to the wirelessInternet by 2010.

NTT DoCoMo and Hewlett-Packard Company &MOTOmediacollaboration will explore new mobile serviceconcepts in which people, places and things will be ableto interact, thereby bridging the real and the cyber world.MOTO-media is expected to enable high performancestreaming of multimedia content to mobile users.DoCoMo and HP aim to nish the shared study of basictechnology by 2003 and hope to push for 4G in 2006.

IX. SUGGESTIONS

We would like to give the following suggestions for thedevelopment of 4G mobile technologies:

1. Technologies like 4G must be developed to integrateinto a more flexible network that grow within thenetwork so that we don't have to scarp the old network toimplement the next generation, the generations to come.

2. The very big challenge for developing a technology isproper human resource for building high quality systems.Big organization, which is engaged in software andsystem development, should rapidly go for tie-ups witheducational institutes for better manpower and knowledgemanagement.

3. We talk about mobile multimedia that 4G will supportbut in reality people are not going to watch TV whilethey walk down the street. Likewise people will not buyCoca Cola at vending machines with a cell phone. Quitoften services conjured up by the engineering side of thevendor organizations has little to do with the reality. Sowireless industry should ponder well about marketdemand and invest money so that they will not be at loss.

X.CONCLUSION

4G should make a significant difference and addperceived benefit to an ordinary person’s life over 3G.We should drop the 2.5G, 3G, 4G speak altogether wherean additional “G” means merely an increase in capacity.What really means something for the users are newservices, integration of services, applications etc. Ourgoal is to struggle to get a “G”eneration of standards sothat we can take our phone anywhere in the world andaccess any service or communicate with any other userany way we want that will offer connectivity soinexpensively. In short, 4G or WWWW (World WideWireless web) should be a more intelligent technologythat interconnects the entire world without limits.

二、英文翻译：

下一代无线宽带的目标（4G—5G）

摘要：随着接入技术的增长，语音、视频、多媒体和宽带数据业务正在集成到同一个网络中去。第三代移动通信网络（3G）将在不远的将来被下一代无线网络——第四代移动通信网络（4G）所取代。4G技术基于IP的服务，其目标是提供高速率，大容量，低每比特消耗的网络。4G的是一个基于开放的系统方法综合的全球的网络。4G的目标是“以一个基于IP的控制、视频、分组数据和V oIP 标准蜂窝网络，取代现有的的增殖核心蜂窝系统网络。不过，虽然尚未真正到达的3G时代，研究人员仍然希望2010年左右能为他们设想到的一个尚未定论的“无线世界”的发展作出贡献，让它最终可以投入使用。本论文着眼于从基本法则和问题上讨论网络、技术、频谱问题、标准、终端，和4G服务的相关愿景——网络运营商和服务供应商对第四代移动通信系统的演化的追寻以及从他们的角度来看未来的研究长远需求在何处？

关键词：无线第四代移动通信正交频分多工多载波码分多址大区域同步码分多址技术超宽带

1、前言

运营商和手机制造商显然有自己全面应对3G的策略，与此同时一些企业已经把目光投向了这种下一代无线技术和网络。4G单纯是学术研发实验室想要主动超越关于3G部署方面所遇到麻烦局限和问题，满足其承诺的性能和吞吐量的问题的努力。虽然这还没有完全达到3G的但为什么研究人员和厂商仍然都对4G 表现出了越来越大的兴趣？两个主要领域是处理这一问题的举措分别包括：增大无线通信链路的容量，以及在异构无线接入网络的无缝移动率。第2节讨论内容是在3G技术创造有利4G技术发展条件的问题。第3节关于技术发展演变的过程和比较，第4节描述4G的目标和远景，第5节对4G技术作出了一些阐释，

而在之后的其他章节中，对4G技术发展的研究和有关的其他问题进行了讨论。

2、无线宽带的演化和比较

3G网络正处于发展过程中一个非常痛苦的阶段，随着初期试验带来的令人失望的结果、成本膨胀、技术故障，网络运营商被迫通过不切实际的炒作紧缩最初的期望。尽管现在围绕着兴建中的更高速度的3G移动网络炒作层出不穷，但是迈向4G的飞跃的原因还是有一下几点：

A.性能

工业怀疑论者表示，用户将不能够通过3G无线网络利用丰富的多媒体资源。4G通信将采用有极高品质几乎等同于高清晰度电视的视频通信。此外，它将能用比3G无线网络快约260倍超过100 Mbps的速度无线下载网上的东西。

B.互操作性

3G的多种标准使网间漫游和互操作有一定困难。我们需要一个全球标准来提供全球性的流动性和可携性服务，使服务提供商不再受单一系统供应商的专有设备的约束。

C.组网

3G的主要是基于一个广域的概念。我们需要混合网络，它能同时利用无线局域网（热点）的概念和信元或基站广域网的设计。有了4G技术，世界各地将有基站，确保手机用户随时随地连接到高速网络。

D.带宽

我们需要更大带宽和更高的比特率。4G技术被安装在办公室、居民区、咖啡店、机场贵宾室，拥有超过20 Mbps的传输速度，将以覆盖局域网内“热点”区域提供高带宽的服务。远离这些热点，客户可以连接到加大马力的2G的语音和数据网络覆盖范围。

E.技术

与3G不同的是，4G技术将更加类似于现有的技术的集合，而不是一个全新的标准。分析家定义4G为一个现有的2G网络与本地区域网络（局域网）或蓝牙无线网络的无缝结合的网络。

F.趋同性

趋同性牵涉了超过单纯的技术，它是一个未来的共同服务和市场。我们需要这样的网络，它能以最充分的形式利用IP地址融合的语音和数据的能力，而4G 技术将实现。

G.成本

4G系统将被证明比3G便宜得多，因为它们可以建立现有网络之上，并没有要求经营者完全更新设备，不需要运营商购买昂贵的设备来提供额外频谱。此外一个开放系统的IP无线环境可能进一步降低服务供应商的设备成本，而使我们迎来真正的互操作性时代。

H.可扩展性

可扩展性，或者说能够处理越来越多用户和更多元化的服务，给移动网络提供了更多的挑战。“设计可扩展性”，包含的信息可以帮助您满足不断变化的使用需求。由于4G的全IP核心层是容易扩展，它非常适合迎接这一挑战。

3、无线宽带的演化和比较

第一代移动通信系统（1G）：1G的无线移动通信系统，在20世纪80年代初并研发出。1G的无线是模拟，并支持第一代模拟手机。它们包括信令协议被熟知为七号信令（信令系统7）。

第二代移动通信系统（2G）：2G系统，在80年代后期派生出，其主要目的是用于语音传输和数字PCS。

第三代移动通信系统（3G）：在无线3G将是一种从容不迫迁移到速度更快，数据中心化的无线网络。当前的目标是从125kbps的传输速度提高到200万比特/秒。

第四代移动通信系统（4G）：在现实中，作为2002年第一上半年，4G技术是一个概念框架或讨论问题，来解决一个普遍的高速无线网络，将与有线骨干网络接口无缝未来的需要。

4、关于4G网络的设想

4G技术可以被想像成作为一个集成的无线系统，使技术之间的无缝漫游。用户可以运行在蜂窝技术网络和将信息交付给一个以卫星为基础的网络也可以固定无线网络为支持，这取决于网络的覆盖范围和收费的优惠。

A.目标

开放移动联盟（OMA）的主要目标是确保不同的无线服务和设备一起工作，和不同国家、运营商和移动终端。在该联盟的纲领里的其他计划包括：

?提供基于开放标准和规范的市场和客户的需求。

?创建和促进在建筑行业的共同框架的看法。

?帮助巩固标准组织，并与其他现有的标准组织和团体一起工作。

B.综合视野

?20 Mbps的数据传输速率

?流媒体音频/视频

?非对称访问

?自适应调制/编码

?动态数据包分配

?智能/自适应天线支持

C.4G的网络架构

“第四代”无线网络组织沿基于IP的核心网络,可以实现全球路由以更为人性化的局域网络，支持无线接入功能，如动态切换和专程路由以及更多新的要求诸如自我更新、服务质量、多播，内容缓存等。

4G局域网将被安装在火车和卡车，以及建筑物，甚至只是一个临时的设备之间发生属于无线电另外一个范围内的随机集合而形成的。在这样的网络路由，路由将取决于已经在开发中的新的架构，由IEEE和欧洲的项目称为移动IP网络的发展（MIND）。

D.工作原理

在4G式移动IP，每个手机分配一个永久的“固有”的IP地址，还有一个“转移”地址，表示其实际位置。当一个地方连接在互联网上的计算机要和手机进行通信，它首先发送一个数据包到手机的固有住址。目录服务器通过家庭网络

把转移地址以常见的移动电话的IP形式转发到一个虚拟隧道中去。然而，目录服务器也将消息发送到计算机，通知它的正确的转移地址，以便今后的数据包可以直接发送。这需要启用TCP会话和HTTP下载去维持不同类型的网络之间用户的移动。由于众多地址和子网的多层次，IPv6是需要这种类型的流动性。

5、4G的支持技术

在4G技术中的革命将是光网络，新的空中接口，便携式设备等。

A.传输协议

1）频分多工（OFDM）：OFDM是一种数字调制技术，它在一个时间符号波形，数千正交波型多路复用。这是高带宽数字数据良好过渡。

2）正交频分多工（W-OFDM）：W-OFDM系统使数据在多个高速无线电频率的编码同时进行。这提供了更高的安全性，提高对海量数据的发送，并在行业中最有效地利用带宽。W-OFDM系统可以实现多点的低功耗RF网络，最大限度地减少与邻近网络的干扰。这使得我们能够拥有独立的渠道，允许在多点网络和点对点骨干系统被覆盖在同一频段中。

3）多载波码分多址方式（MC-CDMA）：MC-CDMA系统实际上是一个覆盖了CDMA网络的OFDM网。类似的单载波CDMA系统中，用户复用正交码来区分在MC - CDMA网络中（即多载波）的用户。在MC - CDMA系统，但每个用户可以分配多个代码，其中数据是在时间或频率的传播。

4）大面积同步码分多址系统（LAS-CDMA）：LAC（航空通信链路）是LAS-CDMA 技术（大面积同步码分多址）这一G4无线通信专利技术的开发商。LAS-CDMA 技术实现高速数据，语音容量的增加，最新创新的解决方案，客户查证，融合了卓越的数据传输特性的高效的时分双工高频LAS-CDMA技术。由此产生的结合使客户查证最频谱效率，高容量双工系统如今成为可能。

B.无线电超宽带无线接口

为了使4G真正进行工作需要将载频迁移到超宽带（UWB）技术。超宽带无线电将为提供必要的新的无线和有线宽带带来实惠，而不需要使用珍贵和稀有的无线电频率。相反，与传统的通信相比，数字视频、语音和数据功能的使用的能源是

已存在的调制脉冲的能量。UWB无线电解决了多径衰落问题，比CDMA进程高效1000％。

C.LMDS网络系统

本地多点分配系统（LMDS）是宽带无线技术来提供语音，数据，互联网和视频服务在25 GHz和更高的频谱（根据认证）。LMDS系统的简称，是来自以下方面：

L (local)本地—都表示在这个频率范围的信号传输特性限制了单信网站的潜在覆盖面积;

M (multipoint)多点—表明信号以点对多点或广播方式传送资料;

D (distribution)分配—指的是信号的分配，这可能包括同步语音、数据、互联网和视频流量;

S (service)服务—意味着运营商之间的用户和客户关系的性质。

6、4G的潜在应用

1)虚拟存在：4G系统为移动用户提供一个“虚拟的存在”——例如，无论他们是在现场或关闭，永远在线的连接使人们参与商业活动。

2)虚拟导航：远程数据库包含的街道、建筑物图形表示，以及特大型城市的物理特性。这个数据库块在传输媒介上高速传输序列，其中一渲染程序允许住户可视化环境的未来。

3)远程医疗：4G技术将支持病人远程健康监测。比如护理人员协助在偏远地点的交通意外受害人必须获取医疗记录，可能需要从一个外科医生的紧急干预视频会议的援助。辅助继电器可能需要从当地医院带回到受害人的X-射线照片。4)远程地信的应用：地理信息系统（GIS），全球定位系统（GPS）的组合，以及高容量的无线移动系统将启用一个新的应用类型称为远程地理处理。查询依赖于几个用户的位置信息，除了时间方面还有许多应用。

5)危机管理应用：目前自然灾害可能会影响整个通信基础设施使之处于混乱之中。迅速恢复通信是必不可少的。随着宽带无线移动通信和互联网视频服务，可以在数小时之内重新建立，而不是数天甚至需要几个星期来有线通信恢复。

6）教育：教育机会将在互联网上公布，为对终身教育有兴趣的个人，将无法向客户端由于提供宽带有线互联网接入的经济偏远地区。4 G无线通信提供这些情况具有成本效益的替代方案。

7、无线产业建议的作用

我们正将对专业人士的应注意以下问题和必须解决的问题进行分析：

标准化：标准化的无线网络中的调制技术、交换计划以及漫游是一个4G的绝对必要的部分。我们必须更加重视普遍意义的先进技术。

更低的价格只比二者选一高一点：商业远见应该做一些经济模型，才开始4G的炒作。他们应该明白4G的数据应用，如视频流应用程序必须具有非常低的成本才能和有线竞争。

全球范围内监管机构之间协调频谱：我们必须要求几乎是免费的频谱未必没有执照的频谱监管机构必须涉及，来指导并说明该频带可能是参与4G研究的人员所使用。

监管框架：政策与监管环境，能够提供透明，公平竞争的确定性和场是必要的。最重要的是，我们应该认识到，规管架构既是一个不断发展的技术问题，又是准备以一种开放的胸襟和务实态度的迎接变化的过程，需要始终牢记行业和消费者的利益。

更多的学术研究：高校必须花更多钱在解决无线电通信上，特别是多频带（和宽带无线电，智能天线和信号处理的基本问题更加努力)。

语音独立的商业理由的思考：工商及科技管理人员不应该偏向使用语音频道，经济因素对数据应用的商业模式。声音有一个内置的需求极限 - 数据应用没有。

整合跨不同拓扑的网络：网络架构必须立足于一体的混合网络的概念，广泛地区无线网络，无线局域网（IEEE 802.11a的的IEEE 802.11b，IEEE 802.11g 标准，其架构包括IEEE 802.15和IEEE 802.16），以纤维为基础的互联网骨干蓝牙。宽带无线网络必须是这个综合网络架构的一部分。

非破坏性的实现：从3G升级到4G技术预计将无缝最终没有设备需要升级的用户。

8、4G的发展

AT＆T是结合的W - OFDM和EDGE技术，提供宽带在高达10 Mbps的下行峰值速率的移动访问，同时以384Kbps的EDGE提供一个800KHz Kbps的上行接入高带宽的移动环境。

Sun微系统实验室正在建设的4G的承诺纳入一个基于IP的移动通信语音和数据无线网络技术。

在印度的卡纳塔克邦政府签署了一项谅解备忘录，从比佛利山庄，加利福尼亚州和印度软件技术园在卡纳塔克邦与迷住科技公司开发的4G无线技术。该项目计划使用无线技术对IEEE802.11a和网络为基础的无线局域网设计了基于IEEE802.11b标准，支持高达11Mbps的数据速率和54Mbps的分别。我们的目标是要连接到无线互联网，到2010年60亿人。

日本NTT DoCoMo公司和惠普公司与MOTO media合作将探索新的移动服务在人们的观念，地方和东西可以互动，从而弥补现实和网络world. MOTO媒体预计将能使高性能的多媒体流的内容移动users. DoCoMo和惠普的目标是尼什2003年之前基本技术共同研究，并希望在2006年推动的4G。

9、几点建议

我们要给4G移动技术的发展提出以下建议：

1、像4G这样的技术必须发展整合成为一个更灵活的网络，那么我们大可不必旧的网络执行下一代网络的要求，因为下一代总会来到。

2、开发一种挑战非常大的技术是正确的建设高质量系统.从事软件和系统开发时，庞大的组织应迅速为融合与教育机构的连线去寻求更好的人力资源和知识管理。

3、我们谈论4G的移动多媒体支持，但在现实中的人都不会看电视，而他们走在街上。同样，人们也不会买的手机自动贩卖机与可口可乐。常常恳求退出服务的供应商组织工程朝上没有多大的现实。因此，无线产业应该思考和对市场需求和投资的钱，那样他们才不会亏损。

10、结论

4G技术应该有显着差异，并添加了知觉3G.We利于常人的生活应该放弃2.5代，第三代，第四代发言完全在一个额外的“G”的手段只是在capacity.What 增加对用户的真正意义的东西都是新的服务，服务一体化，应用等我们的目标是斗争获得的“G”neration使我们可以在世界上访问任何服务或与任何其他用户任何方式任何地方，我们希望我们的电话这将提供连接那么便宜。总之，4G或WWWW（环球无线网络）应是一个更聪明的互连技术，没有限制了整个世界。