外文翻译 2.doc

毕业设计(论文)外文资料翻译学 院： 信息工程学院 专 业： 通信工程 姓 名： 陈宇 学 号： 0906220123 (用外文写)外文出处： the current status of rof 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语： 签名： 2013 年4月 26 日附件1：外文资料翻译译文 光载无线系统的现状 在光载无线通信系统中，由于光载波上承载的是模拟的微波信号，与传统的数字光纤传输链路相比，其系统对光器件的性能以及链路自身的色散、非线性效应等都有了更为苛刻的要求。目前，对于光载无线通信技术的研究仍然集中在物理层上，例如基于微波光子学的毫米波信号源产生，光调制器、滤波器的特性分析与改进，光纤链路的色散控制，以及基站中光载波的再利用等系统设计与优化。其中，以毫米波信号源的产生技术为例，传统的高频信号发生源需要昂贵的本振源，可以利用光波的外差混频技术来得到高频载波。在雷达或光纤无线电（光载无线通信）通信系统中，在光域里对中频微波信号进行上变频，可以得到承载高数据率的毫米波信号，目前比较成熟的技术有，基于强度调制器、基于eam中xam效应、基于soa中xgm效应、基于高非线性光纤中的xpm或fwm效应的全光频率上变换技术。目前，ieee收录的电子期刊以及其他光学权威期刊optics letters、optics express等都刊载了大量关于光载无线通信的文章，但是，这些研究都停留在对信号处理技术以及链路系统研究的层面上，对网络层次的研究成果较少。一种技术的成熟必定要依赖于市场的驱动进而产生利润。光载无线通信技术要在实际通信系统中应用，还有许多现实的问题需要研究。例如：网络融合中的接口问题，mac协议的问题，天线的更高增益问题以及高速移动在微微蜂窝中频繁切换的问题和多普勒效应问题等等。在研究领域，美国乔治亚理工大学的张教授研究组对40g/60g射频光载无线通信系统作了大量的研究，并且搭建出了一套光无线传输系统，将dvd存储的高清晰电视数据源调制到40g的微波上，然后经过调制到光载波上传输，经过探测接收并由天线发射，并在接收端将信号送给高清晰电视进行播放，得到很好的实验效果。但是，发射天线和接收天线的距离很近并且容易受水蒸气的干扰。不久前，ofc 2008会议在美国加州圣地亚哥成功举行，网络融合成为一个热点话题，关于光载无线通信技术的文章也有很多被收录其中，与以往不同，这次收录的光载无线通信论文都趋向于对应用的研究。其中比较典型的文章有：将正交频分复用(ofdm)应用于光载无线通信系统，来增加频谱利用率并减小码间干扰；研究在上行传输时光波长再利用技术，从而去掉基站的光源；基于wimax或wifi与光载无线通信技术结合的研究；基于光分叉复用器(oadms)的光载无线通信系统环形网络的研究；基于多模光纤和塑料光纤的光载无线通信系统。光纤无线电（光载无线通信）被认为是很有前途和有研究价值的课题，尤其在路途车辆系统中，利用光载无线通信技术我们可以将多业务无线电信号通过光纤传送。在日本可用的无线业务很多，比如pdc（800mhz/1500mhz）、phs（1900mhz）、vics（2.5ghz）、fm商用无线电（70-90mhz）、tv广播（90-770mhz）和etc（5.8ghz）。为了降低空中接口数量，已经建议采用基于光载无线通信的发送技术。另外，在下一代网络中，在一些热点区域，如商场，机场等，光载无线通信都将具有诱人的应用前景。例如在国外，基于光载无线通信技术的分布式天线系统(das)已经应用于许多热点区域。总之，光载无线通信技术在未来光无线融合的潮流中必将扮演越来越重要的角色。光载无线通信技术充分结合光纤和高频无线电波传输的特点，能实现大容量、低成本的射频信号有线传输和超过1gbits的超宽带无线接入，并具有覆盖面广、易于动态管理和维护等特点，尽管目前市场不是很大，但随着微波光子技术的发展，光载无线通信系统将会在未来的宽带无线通信领域占有很大的市场份额。光载无线通信系统具有的优点，除了宽带无线接入，还可以应用于室内覆盖、基站客栈、车载无线通信系统以及军事用途中。在未来泛在超宽带蜂窝网络、室内无线局域网络、卫星通信、视频分布式系统、智能交通通信和控制等领域具有巨大的应用前景。令人注目的是60 ghz附近的毫米波作为无线信号载波的毫米波光载无线通信通信。在这个波段，由于大气中氧的存在，信号衰减很快(1015 db/km)，这一原本是缺点的性质正好自然实现了不同基站之间的无干扰以及很好的保密性，提高了频谱利用效率。而这一高频率的附近以“ghz”为单位的宽广频带以及不需要频率使用授权，足以实现超大容量超高速通信的需求。同时，在这个波段的射频设备可以实现很小的尺寸，由于mmic技术的迅速发展，使得低成本的射频集成电路和天线单元日趋可能。 附件2：外文原文 in optical wireless communication system, because of carrying on an optical carrier is a microwave signal simulation, compared with the traditional digital optical fiber transmission link, the system of optical device performance and link their dispersion, nonlinear effect are the more demanding requirements. at present, for the study of optical wireless communication technology are still concentrated in the physical layer, such as the millimeter wave signal source based on the generated microwave photonics, analysis and improvement of spatial light modulators, filters, dispersion control optical fiber link, and the base station of the optical carrier reuse system design and optimization. among them, the millimeter wave signal source generating technology as an example, the traditional source of high frequency signal the need for expensive local oscillator, can come to the high frequency carrier wave by using heterodyne mixing technique. in radar or radio-over-fiber (rof) communication system, frequency of intermediate frequency of microwave signals in the optical domain, can get millimeter wave signal carrying high data rate, the more mature technology, based on the intensity modulator, based on xam effect, eam to soa, based on the optical xgm effect the frequency of high nonlinear fiber xpm or fwm effect on transformation technology. at present, the electronic journals cited by ieee and other optical journals optics letters, optics express, published a large number of optical wireless communication articles, however, these studies have to stay on the signal processing techniques and the level of link system research, to the network level and less research. drive a technology must rely on the market to generate profits. optical wireless communication technology to be applied in the actual communication system, there are many practical problems need to be studied. for example: the interface problem in network integration, mac agreement, more high gain antenna and high-speed mobile frequently in a picocell switching problem and doppler effect etc. in the field of research, professor zhang study group of the united states georgia polytechnic university of 40g/60g rf optical wireless communication system made a lot of research, and build a set of optical wireless transmission system, microwave dvd stored high-definition television modulation to the 40g data source, and then through the modulated on optical carrier transmission, after detection of receiving and by the antenna, and a signal is sent to a high-definition tv play at the receiving end, get good effect. however, the transmitting antenna and receiving antenna distance is very close and vulnerable to interference of water vapor. not long ago, ofc 2008 conference held in the united states california santiago success, network integration become a hot topic of optical wireless communication technology, the article also has many is included which, unlike in the past, the collection of optical wireless communication papers tend to study on the corresponding with the. one of the typical article: orthogonal frequency division multiplexing (ofdm) is applied to the optical wireless communication system, to increase the spectrum utilization rate and reduce intersymbol interference; research and utilization technology in uplink transmission of optical wavelengths, thus removing the source base station; research on wimax or wifi and optical wireless communication technology based on combination of; optical add-drop multiplexer (oadms) based on the study of the optical wireless communication system loop network; multimode fiber and plastic optical fiber optical wireless communication system based on. radio-over-fiber (rof) is considered to be very promising and valuable research topics, especially in road vehicle system, using the optical wireless communication technology, we can be more than business radio signal through the optical fiber transmission. in many japanese radio service available, such as pdc (800mhz/1500mhz), phs (1900mhz), vics (2.5ghz), fm commercial radio (70-90mhz), tv broadcast (90-770mhz) and etc (5.8ghz). in order to reduce the number of air interface, has suggested sending light load based on wireless communication technology. in addition, in the next generation network, in some regional hot spots, such as shopping malls, airports, optical wireless communication will have attractive prospects. for example, in a foreign country, distributed antenna system based on optical wireless communication technology (das) has been applied in many areas. in short, the wireless communication technology in the future will certainly optical wireless integration trend is playing a more and more important role. combined with the characteristics of fiber and high frequency radio transmission of optical wireless communication technology, can realize the cable transmission of radio frequency signals of large capacity, low cost and more than 1gbit / s ultra broadband wireless access, and has the characteristics of wide coverage, easy to dynamic management and maintenance, although the market is not great, but with the development of microwave photonic technology, rof communication system will occupy a large market share in the future broadband wireless communication field. the advantages of optical wireless communication system has, in addition to broadband wireless access, but also can be applied to the indoor coverage, base station inn, wireless communication system and military applications. in the future ubiquitous broadband cellular network, indoor wireless local area network, satellite communications, video distribution systems, intelligent traffic communication and control in the field with a great application prospect. impressiveness is near 60 ghz millimeter-wave wireless signal as the carrier of millimeter-wave wireless communication. in this band, due to the presence of atmospheric oxygen, signal attenuation soon (10 15 db/km), the original is the shortcomings of the nature is natural achieved between different base stations without interference and good security, improve the efficiency of spectrum utilization. this high frequency near to ghz as a unit of broad band and no need for frequency use authorization, to achieve ultra large.我的大学爱情观目录：1、 大学概念2、 分析爱情健康观3、 爱情观要三思4、 大学需要对爱情要认识和理解5、 总结1、什么是大学爱情：大学是一个相对宽松，时间自由，自己支配的环境，也正因为这样，培植爱情之花最肥沃的土地。大学生恋爱一直是大学校园的热门话题，恋爱和学业也就自然成为了大学生在校期间面对的两个主要问题。恋爱关系处理得好、正确，健康，可以成为学习和事业的催化剂，使人学习努力、成绩上升；恋爱关系处理的不当，不健康，可能分散精力、浪费时间、情绪波动、成绩下降。因此，大学生的恋爱观必须树立在健康之上，并且树立正确的恋爱观是十分有必要的。因此我从下面几方面谈谈自己的对大学爱情观。2、什么是健康的爱情：1) 尊重对方，不显示对爱情的占有欲，不把爱情放第一位，不痴情过分；2) 理解对方，互相关心，互相支持，互相鼓励，并以对方的幸福为自己的满足; 3) 是彼此独立的前提下结合；3、什么是不健康的爱情：1)盲目的约会，忽视了学业;2)过于痴情，一味地要求对方表露爱的情怀，这种爱情常有病态的夸张;3)缺乏体贴怜爱之心，只表现自己强烈的占有欲;4)偏重于外表的追求;4、大学生处理两人的在爱情观需要三思：1. 不影响学习：大学恋爱可以说是一种必要的经历，学习是大学的基本和主要任务，这两者之间有错综复杂的关系，有的学生因为爱情，过分的忽视了学习，把感情放在第一位；学习的时候就认真的去学，不要去想爱情中的事，谈恋爱的时候用心去谈，也可以交流下学习，互相鼓励，共同进步。2. 有足够的精力：大学生活，说忙也会很忙，但说轻松也是相对会轻松的！大学生恋爱必须合理安排自身的精力，忙于学习的同时不能因为感情的事情分心，不能在学习期间，放弃学习而去谈感情，把握合理的精力，分配好学习和感情。3、 有合理的时间；大学时间可以分为学习和生活时间，合理把握好学习时间和生活时间的“度”很重要；学习的时候，不能分配学习时间去安排两人的在一起的事情，应该以学习为第一；生活时间，两人可以相互谈谈恋爱，用心去谈，也可以交流下学习，互相鼓励，共同进步。5、大学生对爱情需要认识与理解，主要涉及到以下几个方面：（1） 明确学生的主要任务“放弃时间的人，时间也会放弃他。”大学时代是吸纳知识、增长才干的时期。作为当代大学生，要认识到现在的任务是学习学习做人、学习知识、学习为人民服务的本领。在校大学生要集中精力，投入到学习和社会实践中，而不是因把过多