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.