现代通信网络技术论文范文英文版翻译

现代通信网络技术论文范文英文版翻译

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A virtual world is an interactive simulated environment accessed by multiple users through an online Virtual worlds are also called "digital worlds，" "simulated worlds" and "MMOG'" There are many different types of virtual worlds， however there are six features all of them have in common: Shared Space: the world allows many users to participate at Graphical User Interface: the world depicts space visually， ranging in style from 2D "cartoon" imagery to more immersive 3D Immediacy: interaction takes place in real Interactivity: the world allows users to alter， develop， build， or submit customized Persistence: the world's existence continues regardless of whether individual users are logged Socialization/Community: the world allows and encourages the formation of in-world social groups like teams， guilds， clubs， cliques， housemates， neighborhoods， --------------------------------------------------------------------------------Virtual worlds have been created for many different The largest and most common type of virtual world is the "MMORPG" which stands for "Massively Multiplayer Online Role Playing G" But virtual worlds have also been built for purposes other than The following section summarizes a few ways in which virtual worlds are currently used: Commercial GamingCommercial gaming worlds tend to focus on a singular fictional theme and consistently follow formal conventions such as character-focused avatars， progression through an interactive narrative storyline， and a series of competitive Strongly influenced by fantasy， science fiction， and anime genres of literature and film， the majority of sizable virtual worlds in existence today are commercial gaming Examples include Everquest， Lineage 2， and World of W While Virtual Worlds Review includes several top-quality gaming worlds on the review list， we mostly feature worlds that fall outside the traditional gaming Fortunately there are many other great sites that contain comprehensive lists of commercial gaming Here are a few: MPOGD Gamespot Gamespy Socializing / Online Community BuildingIn addition to the traditional fantasy RPG worlds， there are many commercial community-focused virtual worlds that emphasize socializing rather than These worlds offer a more open-ended experience and are strongly influenced by the cultures of text-based chat Although small-scale， casual games may be incorporated into a social world， participants are not necessarily there to win or play a game， but rather to socialize with others and， in many cases， create and decorate a personal space such as a home， room， or Social worlds tend to use settings based on idealized versions of Most provide some basic building tools and the ability to host activities and events that revolve around a wide variety of EducationSome virtual worlds have been created for educational In most cases， educational worlds are sponsored by academic institutions or nonprofit organizations， although some educational worlds are sponsored by Educational worlds come in a wide variety of forms， including 3D recreations of museum and gallery spaces， computer programming tutorials， virtual libraries， and meeting spaces for online university Active Worlds Educational Universe is one of the oldest and largest networks of educational Adobe Atmosphere is also being used to build virtual worlds for educational A great example of a corporate-sponsored educational world is M Political ExpressionVirtual worlds can serve as forums for political expression and While real-world political issues can crop up in gaming， social， and educational worlds， there are a few cases in which completely separate virtual worlds have been built for the purpose of political debate or even experiments in various types of self-governing online A great example of a virtual world with a political focus is AgoraX Military TrainingVirtual world technologies are also being used in some interesting ways by the US America's Army is being used as a tool to recruit potential soldiers， while companies like Forterra Systems are working with military groups to develop training And this is just the As these technologies develop further over the next several years， virtual worlds will be used for all types of purposes as more people begin spending more time in If you're new to the "world of virtual worlds" we hope that Virtual Worlds Review will serve as a user-friendly， informative place to learn a bit about For those who are already familiar with virtual worlds， we hope the site will let you know about other types of worlds you may not have heard of In either case， welcome and enjoy the -------------------A virtual world is a computer-based simulated environment intended for its users to inhabit and interact via These avatars are usually depicted as textual， two-dimensional， or three-dimensional graphical representations， although other forms are possible[1] (auditory[2] and touch sensations for example) Some， but not all， virtual worlds allow for multiple The computer accesses a computer-simulated world and presents perceptual stimuli to the user， who in turn can manipulate elements of the modeled world and thus experiences telepresence to a certain [3] Such modeled worlds may appear similar to the real world or instead depict fantasy The model world may simulate rules based on the real world or some hybrid fantasy Example rules are gravity， topography， locomotion， real-time actions， and Communication between users has ranged from text， graphical icons， visual gesture， sound， and rarely， forms using touch and balance Massively multiplayer online games commonly depict a world similar to the real world， with real world rules and real-time actions， and Communication is usually textual， with real-time voice communication using VOIP also [clarify]Virtual worlds are not limited to games but， depending on the degree of immediacy presented， can encompass computer conferencing and text based HistoryThe concept of virtual worlds predates computers and could be traced in some sense to P[5] The mechanical-based 1962 Sensorama machine used the senses of vision， sound， balance， smells and touch (via wind) to simulate its Among the earliest virtual worlds to be implemented by computers were not games but generic virtual reality simulators， such as Ivan Sutherland's 1968 virtual reality This form of virtual reality is characterized by bulky headsets and other types of sensory input Contemporary virtual worlds， multi-user online virtual environments， emerged mostly independently of this virtual reality technology research， fueled instead by the gaming industry but drawing on similar [6] While classic sensory-imitating virtual reality relies on tricking the perceptual system into experiencing an imersive environment， virtual worlds typically rely on mentally and emotionally engaging content which gives rise to an immersive The first virtual worlds presented on the Internet were communities and chat rooms， some of which evolved into MUDs and MUSH MUDs， short for “Multi User Dungeons，” are examples of virtual worlds that consist of virtual space inhabited by representations of data and other users [7] Early virtual worlds were text-based， offering limited graphical representation， and often using a Command Line IMaze War (also known as The Maze Game， Maze Wars or simply Maze) was the first networked， 3D multi-user first person shooter Maze first brought us the concept of online players as eyeball "avatars" chasing each other around in a ” (-VCF7-MazeWar/html， 29th Feb) According to the website this was in 1974， it was played on Arpanet (the initial internet)， however it could only be played on an Imlac， as it was specifically built for this type of Then in 1978 MUD was released， it however was not 3D， it was text-based and used a TELNET program， by following the link you will be able to play the game， and understand just how far virtual worlds have come since -/ You can understandably argue whether or not this is a “virtual world” and that Maze War was more sophisticated (being 3D)， but you must understand that MUD could be played by anyone， Maze War was computer Perhaps in today’s senses it is not a true virtual world， but the idea of a virtual world in those days were different (see Neuromancer link in bibliography for more information)Some early prototyptes were WorldsAway， a prototype interactive communities featuring a virtual world by CompuServe called Dreamscape， Cityspace， an educational networking and 3D computer graphics project for children， and The Palace， a 2-dimensional community driven virtual However， credit for the first online virtual world usually goes to Habitat， developed in 1987 by LucasFilm Games for the Commodore 64 computer， and running on the Quantum Link service (the precursor to America Online)[citation needed]In 1996， the city of Helsinki， Finland with Helsinki Telephone Company (since Elisa Group) launched what was called the first online virtual 3D depiction intended to map an entire The Virtual Helsinki project was eventually renamed Helsinki Arena 2000 project and parts of the city in modern and historical context were rendered in 3D[citation needed][edit] Virtual world conceptsOne perception of virtual worlds requires an online persistent world， active and available 24 hours a day and seven days a week， to qualify as a true virtual [citation needed] Although this is possible with smaller virtual worlds， especially those that are not actually online， no massively multiplayer game runs all day， every All the online games listed above[clarify] include downtime for maintenance that is not included as time passing in the virtual While the interaction with other participants is done in real-time， time consistency is not always maintained in online virtual For example， EverQuest time passes faster than real-time despite using the same calendar and time units to present game As virtual world is a fairly vague and inclusive term， the above can generally be divided along a spectrum ranging from:massively multiplayer online role-playing games or MMORPGs where the user playing a specific character is a main feature of the game (World Of Warcraft for example) massively multiplayer online real-life/rogue-like games or MMORLGs， the user can edit and alter their avatar at will， allowing them to play a more dynamic role， or multiple Some would argue that the MMO versions of RTS and FPS games are also virtual worlds if the world editors allow for open editing of the terrains if the "source file" for the terrain is Emerging concepts include basing the terrain of such games on real satellite photos， such as those available through the Google Maps API or through a simple virtual geocaching of "easter eggs" on WikiMapia or similar mashups， where [edit] BoundariesVirtual worlds are well-known as being fantasy spaces sealed off from the real world， but more careful analysis reveals that the boundaries between the real and virtual worlds is quite Participants constantly arrive and depart from the world， carrying with them their unique set of behavioral assumptions and attitudes that cannot be disentangled from their interactions in the virtual [8][clarify] For example， in virtual worlds which bring together players from multiple cultural backgrounds， a participant in a virtual world brings their own cultural preconceptions about those other cultures across the boundary into the world while The term magic circle has been used to describe the imaginary barrier between the virtual world and the real The fantasy environment of the virtual world is protected from the intrusion of real life by this magic circle， but practices such as the sale of virtual items and virtual currency for real life currency challenges this separation while reinforcing the notion that objects in the virtual world have real life In a 2001 study by Edward Castronova， the value of the currency in the MMORPG Everquest was evaluated based on its exchange rate at USD 0107， making this unit of virtual currency of higher value than the Yen or the LEven though Virtual Worlds are most of the time seen as 3D Games， there are many different kinds of it: forums， blogs， wikis and chatrooms where communities Places which have their own world， their own rules， topics， jokes， members， Each person who belongs to these kinds of communities can find like-minded people to talk to， whether this be a passion， the wish to share information about or just to meet new people and experience new Some users develop a double personality depending on which world they are interacting Depending on whether that person is in the real or virtual world can impact on the way they think and It is not all about video games and communities， virtual world also plays a part in the social as it can allow people to speak or share knowledge with each Best examples are instant messaging and visio-conferences which allow people to create their own virtual It can also be used to help hospitalized children (suffering from painful disease or autism for example) to create a comfortable and safe environment which can help Although Virtual Worlds can be seen as a new way for people to socialize， they are said to be at the heart of a lot of anti-social People playing video games online and more precisely， MMORPG are sometimes so addicted to the game that they cannot live without playing Such people are called “No Life” or Otaku and spend most of their time in their house not leaving it for They are often wrongly treated like insane people and also represented as dangerous when criminal cases imply links with video The thing is that video games played online are most of the time designed to be played for a long period of time (and even in the case of World Of Warcraft indefinitely – programmers provide updates and new things to discover regularly) People who abuse this kind of video games end up living most of their live in their bedrooms， do not develop any social life or skills: they communicate with friends mostly via the game or the internet， they create their own life on the internet with a specific name， image and The example of Second Life is totally unique because players develop communities and businesses in this Second Life is a game where the player has to create his/her own character with a human aspect and live a second life in a virtual The thing is that some people are so involved in this game (and created their “own self” in this game) that they have a double

现代通信网络技术论文范文英文版高中

What is TCP/IP? TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the I It can also be used as a communications protocol in a private network (either an intranet or an extranet) When you are set up with direct access to the Internet， your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IPTCP/IP is a two-layer The higher layer， Transmission Control Protocol， manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original The lower layer， Internet Protocol， handles the address part of each packet so that it gets to the right Each gateway computer on the network checks this address to see where to forward the Even though some packets from the same message are routed differently than others， they'll be reassembled at the TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the TCP/IP communication is primarily point-to-point， meaning each communication is from one point (or host computer) in the network to another point or host TCP/IP and the higher-level applications that use it are collectively said to be "stateless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration) Being stateless frees network paths so that everyone can use them (Note that the TCP layer itself is not stateless as far as any one message is Its connection remains in place until all packets in a message have been )Many Internet users are familiar with the even higher layer application protocols that use TCP/IP to get to the I These include the World Wide Web's Hypertext Transfer Protocol (HTTP)， the File Transfer Protocol (FTP)， Telnet (Telnet) which lets you logon to remote computers， and the Simple Mail Transfer Protocol (SMTP) These and other protocols are often packaged together with TCP/IP as a ""Personal computer users with an analog phone modem connection to the Internet usually get to the Internet through the Serial Line Internet Protocol (SLIP) or the Point-to-Point Protocol (PPP) These protocols encapsulate the IP packets so that they can be sent over the dial-up phone connection to an access provider's Protocols related to TCP/IP include the User Datagram Protocol (UDP)， which is used instead of TCP for special Other protocols are used by network host computers for exchanging router These include the Internet Control Message Protocol (ICMP)， the Interior Gateway Protocol (IGP)， the Exterior Gateway Protocol (EGP)， and the Border Gateway Protocol (BGP)

现化通信技术给我们带来方便太多了，从以前为了传输信号用的风火台点狼烟到现在用电话和手机。从以前亲眼看到几百米景物到现在电视捍几千米几千公里里景物。从一个人讲话小范围几十人听到现在几万人或几亿人都能听的音视。从人记录信息甲骨文到现在计算机打印等

(一）摘要摘要是毕业设计（论文）主要信息的简要陈述，具有独立性和完整性。摘要内容包括本论文研究目的、方法、结果、结论四部分。千万不要讲一些人们已经做过的工作。要开门见山地讲本文的主要工作。摘要分中文摘要和外文摘要，中文摘要在前，一般300字左右，外文摘要另起一页，内容应与中文摘要对应。　（二）正文毕业论文正文部分包括前言、主体和结论。前言作为开场白，应以简短的篇幅，说明毕业论文选题的目的和意义、国内外文献综述、研究的内容及预期目标，要求突出重点，实事求是。主体是毕业论文的核心部分，占主要篇幅。毕业论文正文字数一般要求在15000字以上。有创新的论文，字数不受限制。文中插入的图表要符合国家标准，经过精心设计后用计算机绘制，尽量避免扫描图表。结论是整个毕业论文的最后总结，完整、准确、简洁地指出以下内容：（1）毕业论文得到的结果所揭示的原理及其普遍规律；（2）研究中有无发现例外或本文尚难以解释和解决的问题；（3）与同类研究工作的异同；（4）进一步深入研究本课题的建议。（三）参考文献毕业设计（论文）要求有10篇以上的中外文参考文献，其中至少有一篇与设计（论文）内容相关的外文文献。毕业设计（论文）引用的文献应以近期发表的与毕业设计（论文）直接有关的文献为主。凡引用本人或他人已公开或未公开发表文献中的学术思想、观点或研究方法、设计方案等，不论借鉴、评论、综述，还是用做立论依据，都应编入参考文献目录。各条文献按在论文中的文献引用序号顺序排列。

现代通信网络技术论文范文大全

论文摘要：短波的频率范围115MHz - 30MHz ， 传播途径分为地波和天波两种。其中地波因为受地面吸收和地面电气特性的影响而衰减的程度较大， 只适用于短距离通信。因此短波通信的主要传播路径是天波。天波的传播是利用电离层的反射来实现的， 尤其是多次反射后可以实现全球通信。地波传播受天气的影响较小， 比较稳定， 信道参数基本上不随时间的变化而变化， 是恒参信道。 论文名称： 短波在无线电通信中的作用及特点 作 者： 孙 雷 专业类别： 其它 论文来源： 转载 刊载杂志： 上 传 人： HUNANLIANG 发布时间： 2006-2-1 13:29:00 论文星级： ★★★ 文件大小： 88KB 网友评分： 暂无网友打分 人 气 数： 192 下载次数： 89 论文性质： 下载:会员200个积分/vip会员0个积分 关 键 字： 地波; 天波; 电离层; 多跳路径

现化通信技术给我们带来方便太多了，从以前为了传输信号用的风火台点狼烟到现在用电话和手机。从以前亲眼看到几百米景物到现在电视捍几千米几千公里里景物。从一个人讲话小范围几十人听到现在几万人或几亿人都能听的音视。从人记录信息甲骨文到现在计算机打印等

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现代通信网络技术论文范文初中

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近来有人对光纤通信的发展情景，有些困惑。其一，在2000年IT行业的泡沫，使光纤通信的生产规模投入过大，生产过剩，IT行业中许多小公司倒闭。特别是光纤，国外对中国倾销。其二，有人认为:光纤通信的传输能力已经达到10Tbps，几乎用不完，而且现在大干线已经建设得差不多，埋地的剩余光纤还很多，光纤通信技术不需要更多的发展。 笔者认为，光纤通信技术尚有很大的发展空间，今后会有很大的需求和市场。主要是:光纤到家庭FTTH、光交换和集成光电子器件方面会有较大的发展。在此主要讨论光纤通信的发展趋势和市场。 光纤通信的发展趋势 1、光纤到家庭(FTTH)的发展 FTTH可向用户提供极丰富的带宽，所以一直被认为是理想的接入方式，对于实现信息社会有重要作用，还需要大规模推广和建设。FTTH所需要的光纤可能是现有已敷光纤的2～3倍。过去由于FTTH成本高，缺少宽带视频业务和宽带内容等原因，使FTTH还未能提到日程上来，只有少量的试验。近来，由于光电子器件的进步，光收发模块和光纤的价格大大降低;加上宽带内容有所缓解，都加速了FTTH的实用化进程。 发达国家对FTTH的看法不完全相同:美国AT&T认为FTTH市场较小，在0F62003宣称:FTTH在20-50年后才有市场。美国运行商Verizon和Sprint比较积极，要在10—12年内采用FTTH改造网络。日本NTT发展FTTH最早，现在已经有近200万用户。目前中国FTTH处于试点阶段。 ◆FTTH[遇到的挑战:现在广泛采用的ADSL技术提供宽带业务尚有一定优势。与FTTH相比:①价格便宜②利用原有铜线网使工程建设简单③对于目前1Mbps—500kbps影视节目的传输可满足需求。FTTH目前大量推广受制约。 对于不久的将来要发展的宽带业务，如:网上教育，网上办公，会议电视，网上游戏，远程诊疗等双向业务和HDTV高清数字电视，上下行传输不对称的业务，AD8L就难以满足。尤其是HDTV，经过压缩，目前其传输速率尚需2Mbps。正在用H264技术开发，可压缩到5～6Mbps。通常认为对QOS有所保证的ADSL的最高传输速串是2Mbps，仍难以传输HDTV。可以认为HDTV是FTTH的主要推动力。即HDTV业务到来时，非FTTH不可。 ◆ FTTH的解决方案:通常有P2P点对点和PON无源光网络两大类。 F2P方案一一优点:各用户独立传输，互不影响，体制变动灵活;可以采用廉价的低速光电子模块;传输距离长。缺点:为了减少用户直接到局的光纤和管道，需要在用户区安置1个汇总用户的有源节点。 PON方案——优点:无源网络维护简单;原则上可以节省光电子器件和光纤。缺点:需要采用昂贵的高速光电子模块;需要采用区分用户距离不同的电子模块，以避免各用户上行信号互相冲突;传输距离受PON分比而缩短;各用户的下行带宽互相占用，如果用户带宽得不到保证时，不单是要网络扩容，还需要更换PON和更换用户模块来解决。(按照目前市场价格，PEP比PON经济)。 PON有多种，一般有如下几种:(1)APON:即ATM-PON，适合ATM交换网络。(2)BPON:即宽带的PON。(3)OPON:采用通用帧处理的OFP-PON。(4)EPON:采用以太网技术的PON，0EPON是千兆毕以太网的PON。(5)WDM-PON:采用波分复用来区分用户的PON，由于用户与波长有关，使维护不便，在FTTH中很少采用。 发达国家发展FTTH的计划和技术方案，根据各国具体情况有所不同。美国主要采用A-PON，因为ATM交换在美国应用广泛。日本NTT有一个B-FLETts计划，采用P2P-MC、B-PON、G-EPON、SCM-PON等多种技术。SCM-PON:是采用副载波调制作为多信道复用的PON。 中国ATM使用远比STM的SDH少，一般不考虑APON。我们可以考虑的是P2P、GPON和EPON。P2P方案的优缺点前面已经说过，目前比较经济，使用灵活，传输距离远等;宜采用。而比较GPON和EPON，各有利弊。GPON:采用GFP技术网络效率高;可以有电话，适合SDH网络，与IP结合没有EPON好，但目前GPON技术不很成熟。EPON:与IP结合好，可用户电话，如用电话需要借助lAD技术。目前，中国的FTTH试点采用EPON比较多。FTTH技术方案的采用，还需要根据用户的具体情况不同而不同。 近来，无线接入技术发展迅速。可用作WLAN的IEEE11g协议，传输带宽可达54Mbps，覆盖范围达100米以上，目前已可商用。如果采用无线接入WLAN作用户的数据传输，包括:上下行数据和点播电视VOD的上行数据，对于一般用户其上行不大，IEEES11g是可以满足的。而采用光纤的FTTH主要是解决HDTV宽带视频的下行传输，当然在需要时也可包含一些下行数据。这就形成“光纤到家庭+无线接入”(FTTH+无线接入)的家庭网络。这种家庭网络，如果采用PON，就特别简单，因为此PON无上行信号，就不需要测距的电子模块，成本大大降低，维护简单。如果，所属PON的用户群体，被无线城域网WiMAX(1EEE16)覆盖而可利用，那么可不必建设专用的WLAN。接入网采用无线是趋势，但无线接入网仍需要密布于用户临近的光纤网来支撑，与FTTH相差无几。FTTH+无线接入是未来的发展趋势。 2、光交换的发展什么是通信? 实际上可表示为:通信输+交换。 光纤只是解决传输问题，还需要解决光的交换问题。过去，通信网都是由金属线缆构成的，传输的是电子信号，交换是采用电子交换机。现在，通信网除了用户末端一小段外，都是光纤，传输的是光信号。合理的方法应该采用光交换。但目前，由于目前光开关器件不成熟，只能采用的是“光-电-光”方式来解决光网的交换，即把光信号变成电信号，用电子交换后，再变还光信号。显然是不合理的办法，是效串不高和不经济的。正在开发大容量的光开关，以实现光交换网络，特别是所谓ASON-自动交换光网络。 通常在光网里传输的信息，一般速度都是xGbps的，电子开关不能胜任。一般要在低次群中实现电子交换。而光交换可实现高速XGbDs的交换。当然，也不是说，一切都要用光交换，特别是低速，颗粒小的信号的交换，应采用成熟的电子交换，没有必要采用不成熟的 大容量的光交换。当前，在数据网中，信号以“包”的形式出现，采用所谓“包交换”。包的颗粒比较小，可采用电子交换。然而，在大量同方向的包汇总后，数量很大时，就应该采用容量大的光交换。目前，少通道大容量的光交换已有实用。如用于保护、下路和小量通路调度等。一般采用机械光开关、热光开关来实现。目前，由于这些光开关的体积、功耗和集成度的限制，通路数一般在8—16个。 电子交换一般有“空分”和“时分”方式。在光交换中有“空分”、“时分”和“波长交换”。光纤通信很少采用光时分交换。 光空分交换:一般采用光开关可以把光信号从某一光纤转到另一光纤。空分的光开关有机械的、半导体的和热光开关等。近来，采用集成技术，开发出MEM微电机光开关，其体积小到mm。已开发出1296x1296MEM光交换机(Lucent)，属于试验性质的。 光波长交换:是对各交换对象赋于1个特定的波长。于是，发送某1特定波长就可对某特定对象通信。实现光波长交换的关键是需要开发实用化的可变波长的光源，光滤波器和集成的低功耗的可靠的光开关阵列等。已开发出640x640半导体光开关+AWG的空分与波长的相结合的交叉连接试验系统(corning)。采用光空分和光波分可构成非常灵活的光交换网。日本NTT在Chitose市进行了采用波长路由交换的现场试验，半径5公里，共有43个终端节，(试用5个节点)，速率为5Gbps。 自动交换的光网，称为ASON，是进一步发展的方向。 3、集成光电子器件的发展 如同电子器件那样，光电子器件也要走向集成化。虽然不是所有的光电子器件都要集成，但会有相当的一部分是需要而且是可以集成的。目前正在发展的PLC-平面光波导线路，如同一块印刷电路板，可以把光电子器件组装于其上，也可以直接集成为一个光电子器件。要实现FTTH也好，ASON也好，都需要有新的、体积小的和廉价的和集成的光电子器件。 日本NTT采用PLO技术研制出16x16热光开关;1x128热光开关阵列;用集成和混合集成工艺把32通路的AWG+可变光衰减器+光功率监测集成在一起;8波长每波速串为80Gbps的WDM的复用和去复用分别集成在1块芯片上，尺寸仅15x7mm，如图1。NTT采用以上集成器件构成32通路的OADM。其中有些已经商用。近几年，集成光电子器件有比较大的改进。 中国的集成光电子器件也有一定进展。集成的小通道光开关和属于PLO技术的AWG有所突破。但与发达国家尚有较大差距。如果我们不迎头赶上，就会重复如同微电子落后的被动局面。 光纤通信的市场 众所周知，2000年IT行业泡沫，使光纤通信产业生产规模爆炸性地发展，产品生产过剩。无论是光传输设备，光电子器件和光纤的价格都狂跌。特别是光纤，每公里泡沫时期价格为羊1200，现在价格Y100左右1公里，比铜线还便宜。光纤通信的市场何时能恢复? 根据RHK的对北美通信产业投入的统计和预测，如图在2002年是最低谷，相当于倒退4年。现在有所回升，但还不能恢复。按此推测，在2007-2008年才能复元。光纤通信的市场也随IT市场好转。这些好转，在相当大的程度是由FTTH和宽带数字电视所带动的。 笔者认为:FTTH毕竟是信息社会的需求，光纤通信的市场一定有美好的情景。发达国家的FTTH已经开始建设，已经有相当的市场。大体上看，器件和设备随市场的需要，其利润会逐步回升，2007-2008年可能良好。但光纤产业，尽管反倾销成功，目前价格也仍低迷不起，利润甚微。实际上，在世界范围内，光纤的生产规模过大，而FTTH的发展速度受社会环境、包括市民的经济条件和数字电视的发展的影响，上升缓慢。据了解，有大公司目前封存几个光纤厂，根据市场情况，可随时启动生产，其结果是始终供大于求。供不应求才能涨价，是通常的市场规律，所以光纤产业要想厚利，可能是2009年后的事情。中国经济不发达地区和小城镇，还需要建设光纤线路，但光纤用量仍然处于供太子求的范围内。 对中国市场，FTTH受ADSL的挑战和数字电视HDTV发展的制约，会有所延后。目前，中国大量建设FTTH的社会环境和条件尚未具备，可能需要等待一段时间。不过，北京奥运会需要HDTV的推动和设备价格的下降，会促进FTTH的发展。预计在2007-2008年在中国FTTH可开始推广。不过也有些大城市的所谓中心商业区CBD，有比较强的经济力量，现在已经采用光纤到住地PTTP来建设。总的来说，目前中国的FTTH处于试点阶段。试点的作用，一方面是摸索技术和建设的经验，另一方面，还起竞争抢占用户的作用。所以，现在电信运行商，地方业主都积极对FTTH试点，以便发展宽带业务。因此，广播运行商受到巨大的挑战，广播商应加快发展数字电视的进程，并且要充实节目内容和采取有竞争力的商业模式。如果广播商要发展VOP点播电视，还需要对电缆电视网双向改造，如果采用光纤网，可更充分地适应未来的技术发展和市场需求。

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现代通信网络技术论文2000字

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