现代移动通信
在当今高度信息化的社会，信息和通信已成为现代社会的“命脉”。信息的交流主要依赖于计算机通信，而通信作为传输手段，与传感技术、计算机技术相互融合，已成为21世纪国际社会和世界经济发展的强大动力。为了适应时代的要求，新的一代移动通信技术应时而生，新的一代移动通信技术即人们称之第三代的核心特征是宽带寻址接入到固定网和众多不同通信系统间的无隙缝漫游，获取多媒体通信业务。
随着时代的进步、科技的创新、人们的生活要求的提高，移动通信技术更新换代速度相当惊人，差不多每隔十年移动通信技术就发生一次变革性换代，从上个世纪80年代的“大哥大”到现在的3G手机，其间发生了两次移动通信技术的变革，从1G的AMPS过渡到2G的GSM，从GSM到IMT-2000（即3G技术）。就我所知现代的移动通信技术有以下几方面的重要技术：
1.宽带调制和多址技术
无线高速数据传输不能一味仅靠频谱的扩展，应在频谱效率上至少高于目前一个数量级，可在物理层采用三项技术，即OFDM、UWB和空时调制编码。OFDM与其他编码方式的结合，灵活把OFDM与TDMA、FDMA、CDMA、SDMA组合成多址技术。
20世纪60年代OFDM的多路数据传输已成功用于Kineplex和Kathryn高频军事通信系统。OFDM已用于1.6 Mbit/s高比特率数字用户线（HDSL），6 Mbit/s不对称数字用户线（ADSL），100 Mbit/s甚高速数字用户线（VDSL），数字音频广播和数字视频广播等。OFDM应用于5 GHz上提供54 Mbit/s无线本地网IEEE 802.11 a和IEEE 802.11g，高性能本地域网络Hiper LAN/2和ETSI-BRAN，还作为城域网IEEE 802.16和集成业务数字广播（ISDB-T）标准。与单载频调制制式相比，OFDM调制制式要解决相对大的峰均功率比（PAPR，Peak to Average Power Ratio）和对频率位移和相位噪声敏感的问题。
高速移动通信的另一要求是在宽噪声带宽下，所需解调信噪比应尽可能降低，从而增加覆盖面积。可采取抗衰落的快速发射功率控制和导频辅助快速跟踪相干解调技术，如频域抗衰落的Rake接收和跟踪技术，从时域和频域抵抗时间和频率选择性衰落的OFDMA技术，链路自适应技术，联合编码技术。
2.频谱利用率提升技术
理论研究指出：在独立Rayleigh散射信道中，数据速率与天线数成线性关系，容量可达Shannon的90%。在发射和接收端以多天线开发信道空间可取得容量和频谱效率的增益。MIMO技术主要包括空间复用和空间分集技术，在独立信道上并发或连发相同信息来提高传输可靠性。
收发双方的空间分集是高容量无线通信系统采用技术之一。贝尔实验室分层次空时的对角BLAST（D-BLAST）容量的增加为收发双方最小天线数的函数。利用MIMO所构成的跨时域和空域的扩展信号还可以抵抗多径干扰。V-BLAST系统在室内24～34 dB时，频谱利用率为20～40 bit/s/Hz。而发射和接收端均采用16天线，在30 dB时，频谱利用率增至60～70 bit/s/Hz。
智能天线自动跟踪所需信号和自适应空时处理算法，利用天线阵产生空间定向波束，通过数字信号处理技术使主波束对准用户信号到达方向，旁瓣或零陷对准干扰信号到达方向。自适应阵列天线（AAA，Adaptive Antennas）中干扰抵消均衡器（ICE，Interference Canceling Equalizer）可减少干扰和降低发射功率。
3.软件无线电技术
软件无线电技术是在硬件平台上通过软件编辑以一个终端实施不同系统中多种通信业务。它用数字信号处理语言描述电信元件，以软件程序下载成数字信号处理硬件（DSPH，Digital Signal Pocessing Hardware）。以具有通用开放无线结构（OWA，Open Wireless Architecture），兼容多种模式在多种技术标准之间无缝切换。
UWB也称为脉冲无线电，调制采用脉冲宽度在纳秒级的快速上升和下降脉冲，脉冲覆盖的频谱从直流至吉赫兹，不需常规窄带调制所需的射频上变换，脉冲成型后可直接送至天线发射。
4.软件无线电技术
软件无线电技术是在硬件平台上通过软件编辑以一个终端实施不同系统中多种通信业务。它用数字信号处理语言描述电信元件，以软件程序下载成数字信号处理硬件（DSPH，Digital Signal Pocessing Hardware）。以具有通用开放无线结构（OWA，Open Wireless Architecture），兼容多种模式在多种技术标准之间无缝切换。
5.网络安全和QoS
QoS分为无线和有线侧两部分，无线侧的QoS涉及无线资源管理和调度，接纳控制和移动性管理等，移动性管理主要包括终端移动性，个人移动性和业务移动性。有线侧的QoS涉及基于IP diffSer的区分业务和RSVP的端到端资源预留机制。把IP diffSer的IP QoS机制映射到无线侧。网络安全包括网络接入安全，核心网安全，应用安全，安全机制可见性与可配置性。
在上述现代移动通信关键技术的基础上，产生了陆地蜂窝移动通信、卫星通信以及无线因特网通信技术，这些通信方式使通信面貌发生了巨大的变化，采用数字技术的现代无线通信已经渗入国民经济的各个领域和人们的日常生活，为此，我们需要关心它的发展趋势，希望它朝着越来越方便人们的生活的方向发展，现在就让我们来看看现代移动通信的未来发展趋势吧。
现代移动通信技术发展的七个新趋势:
一、移动管理已从终端管理向个人管理和智能管理发展
二、网络已从同步的数字电路向异步的数字分组和异步传递方式(ATM)发展;
三、软件的开发已从算法驱动到面向过程和面向目标的趋势发展;
四、信息处理已从话音发展到数据和图像;
五、无线频谱的处理已从窄带模拟向窄带CDMA发展;
六、计算机已从集中式处理发展到分布式服务器和智能化处理;
七、半导体器件已从每芯片16兆门/150MHz速率的VLSI发展到0.5千兆门/350MHz速率的VLSI和2千兆门 /550MHz速率的 VLSI。
在这种趋势的引导下，移动通信业务迅猛发展，它满足了人们在任何时间、任何地点与任何个人进行通信的愿望。移动通信是实现未来理想的个人通信服务的必由之路。在信息支撑技术、市场竞争和需求的共同作用下，移动通信技术的发展更是突飞猛进，呈现出以下几大趋势：1)网络业务数据化、分组化；2)网络技术宽带化；3)网络技术智能化；4)更高的频段；5)更有效利用频率；6)各种网络趋于融合。了解、掌握这些趋势对移动通信运营商和设备制造商均具有重要的现实意义。
Modern mobile communication technology
In now highly the informationization society, the information and the correspondence have become the modern society “the life”. The information exchange mainly relies on the computer correspondence, but corresponds takes the transmission method, with the sensing technology, the computer technology fuses mutually, has become in the 21st century the international society and the world economic development powerful engine. In order to of adapt the time request, the new generation of mobile communication technology seasonable and lives, the new generation of mobile communication technology is the people said that third generation's core characteristic is the wide band addressing turns on non-gap roaming between the rigid network and numerous different communications system's, gains the multimedia communication services.
Along with the time progress, the technical innovation, people's life request's enhancement, the mobile communication technology renewal speed is quite astonishing, almost every other ten year mobile communication technology has a transformation update, from the 1980s “the mobile phone” to present's 3G handset, during has had two mobile communication technology transformation, transits from 1G AMPS to 2G GSM, from GSM to IMT-2000 (i.e. 3G technology). Knows modern on me the mobile communication technology to have the following several aspect important technology:
1. wideband modulation and multiple access technique
The wireless high speed data transmission cannot only depend on the frequency spectrum constantly the expansion, should be higher than the present number magnitude at least in the frequency spectrum efficiency, may use three technologies in the physical level, namely OFDM, UWB and free time modulation code. OFDM with other encoding method's union, nimbly OFDM and TDMA, FDMA, CDMA, SDMA combines the multiple access technique.
In the 1960s the OFDM multi-channel data transmission has succeeded uses in Kineplex and the Kathryn high frequency military channels. OFDM has used in 1.6 Mbit/s high bit rate digital subscriber line (HDSL), 6 Mbit/s asymmetrical digital subscriber line (ADSL), 100 Mbit/s really high speed figure subscriber's line (VDSL), digital audio frequency broadcast and digital video broadcast and so on. OFDM applies on 5 GHz provides 54 Mbit/s wireless local network IEEE 802.11 a and IEEE 802.11g, high performance this region network Hiper LAN/2 and ETSI-BRAN, but also takes metropolitan area network IEEE 802.16 and the integrated service digit broadcast (ISDB-T) the standard. Compares with the single load frequency modulation system service pattern, the OFDM modulation service pattern needs to solve the relatively big peak even power ratio (PAPR, Peak to Average Power Ratio) and to the frequency shifting and the phase noise sensitive question.
High speed mobile communication's another request is under the wide noise bandwidth, must demodulate the signal-to-noise ratio to reduce as far as possible, thus increases the cover area. May adopt the anti-fading the full start power control and the pilot frequency auxiliary fast track demodulation technology, like the frequency range anti-fading's Rake receive and the track technology, the OFDMA technology which declines from the time domain and the frequency range resistance time and the frequency selectivity, the link auto-adapted technology, the union coding technique.
2. frequency spectrum use factor lift technique
The fundamental research pointed out: In the independent Rayleigh scattering channel, the data rate and the antenna several tenth linear relationships, the capacity may reach Shannon 90%. Is launching and the receiving end may obtain the capacity and the frequency spectrum efficiency gain by the multi-antenna development channel space. The MIMO technology mainly includes the spatial multiplying and the space diversity technology, concurrent or the salvo same information enhances the transmission reliability on the independent channel.
Receives and dispatches the bilateral space diversity is the high-capacity wireless communication system uses one of technical. Bell Lab free time's opposite angle BLAST (D-BLAST) capacity increase to receive and dispatch the bilateral smallest antenna number in administrative levels the function. The cross time domain which and the air zone expansion signal constitutes using MIMO may also resist the multi-diameter disturbance. V-BLAST system when indoor 24~34 dB, the frequency spectrum use factor is 20~40 bit/s/Hz. But launches and the receiving end uses 16 antennas, when 30 dB, the frequency spectrum use factor increases to 60~70 bit/s/Hz.
The smart antenna automatic tracking needs the signal and the auto-adapted free time processing algorithm, produces the dimensional orientation wave beam using the antenna array, causes the main wave beam alignment subscriber signal direction of arrival through the digital signal processing technology, the side lobe or zero falls the alignment unwanted signal direction of arrival. The auto-adapted array antennas (AAA, Adaptive Antennas) disturbs the counter-balance balancer (ICE, Interference Canceling Equalizer) to be possible to reduce disturbs and cuts the emissive power.
3. software radio technology
The software radio technology is in the hardware platform through the software edition by a terminal implementation different system in many kinds of communication services. It uses the digital signal processing language description telecommunication part, downloads the digital signal processing hardware by the software routine (DSPH, Digital Signal Pocessing Hardware). By has the general opening wireless structure (OWA, Open Wireless Architecture), compatible many kinds of patterns between many kinds of technical standards seamless cut.
UWB is also called the pulse to be radio, the modulation uses the pulse width in the nanosecond level fast rise and the drop pulse, the pulse cover frequency spectrum from the cocurrent to the lucky hertz, does not need in the radio frequency which the convention narrow band frequency modulation needs to transform, after pulse formation, may deliver directly to the antenna launch.
4. software radio technology
The software radio technology is in the hardware platform through the software edition by a terminal implementation different system in many kinds of communication services. It uses the digital signal processing language description telecommunication part, downloads the digital signal processing hardware by the software routine (DSPH, Digital Signal Pocessing Hardware). By has the general opening wireless structure (OWA, Open Wireless Architecture), compatible many kinds of patterns between many kinds of technical standards seamless cut.
5. network security and QoS
QoS divides into wireless and the wired side two parts, wireless side's QoS involves the radio resource management and the dispatch, the admission control and the mobility management and so on, the mobility management mainly includes the terminal mobility, individual mobility and service mobility. Wired side's QoS involves based on the IP diffSer discrimination service and the RSVP end-to-end resources reservation mechanism. Mechanism maps the wireless side IP diffSer IP the QoS. Network security including network turning on security, core network security, application security, safety mechanism visibility and configurable.
In the above modern mobile communication key technologies's foundation, has had the land honeycomb mobile communication, the satellite communication as well as the wireless Internet communication, these mailing address caused the correspondence appearance to have the huge change, used the digital technique the modern wireless communication already to permeate the national economy each domain and people's daily life, for this reason, we needed to care that its trend of development, hoped it developed toward more and more convenient people's life's direction, will let now us have a look at the modern mobile communication the future trend of development.
modern mobile communication technological development seven new tendencies :
First, mobility management already from terminal management to individual management and intelligent management development
Second, network already from synchronized digital circuit to asynchronous digital grouping and asynchronous transfer mode (ATM) development;
the three, software's developments actuated from the algorithm to the procedure-oriented and face the goal tendency development;
the four, information processing have developed from the voice to the data and the image;
five, wireless frequency spectrum processing already from narrow band simulation to the narrow band CDMA development;
the six, computers have developed from central processing to the distributional server and intellectualized processing;
the seven, semiconductor devices have developed from each chip 16,000,000,000,000 /150MHz speed VLSI to 0.5 /350MHz speed VLSI and 2,000,000,000,000,000 /550MHz speed VLSI.
Under this tendency's guidance, the mobile service rapid development, it satisfied the people in any time, any place to carry on the correspondence with any individual the desire. The mobile communication realizes in the future the ideal person-to-person communication service way that must be taken. In the information support technology, the market competition and under the demand combined action, the mobile communication technology's development is progresses by leaps and bounds, presents the following several general trends: 1) network service digitization, grouping; 2) networking wide band; 3) networking intellectualization; 4) higher frequency band; 5) more effective use frequency; 6) each kind of network tends the fusion. The understanding, grasps these tendencies has the vital practical significance to the mobile communication operator and the equipment manufacturer.
结课作文
My university life
In my understanding, if we refer to an ideal college life as a formal western dinner, then a high GPA, that is, Grade Point Average, should be the main course, while an active part in activities, together with associations, means the appetizer. Some romances, of course, play the role as desserts. They are the 3 key elements for an ideal college life.
Those, however, are not what college life is all about. As we all know, college is wildly different from middle school. It connects not only adolescence to adulthood, but also the ivory tower to the real society. Therefore, the ideal college life is that I become matured both physically and mentally, and that I obtain qualified academic knowledge and get well prepared for society at the same time.
Under this circumstance, I never expect my college life to be too ideal, or you can call it too perfect. It is not realistic to make all things on my own way, with everyone liking me, winning the first prize all the time, and so on. Of course, I’d like to lead a carefree life. However, this does little good to my future. What really helps is hardships like failure, betrayal, and unjust treatment. Only after experiencing those can I know what society is like, and what life is like.
To conclude my speech, I wanna say, some positive experiences are surely part of the ideal college life. But, I should not forget about the negative sides. They are not less necessary.
通信工程专业英语
结课论文(翻译和作文)
一点的痕迹，山风呼呼，细雨微微。人行翦翦，心韵盈盈。思邃恒古，本义使然，让思想的光芒照亮每个心灵，让身心的热量变作普照大地的明媚，让蠕风的蠢蠢欲动万木复苏的定格。
在这片神圣的土地上，色彩是洁净的象征，静物是可修复的抱朴，人境是可绝缘的尘，合沓车马也无喧。吾生有无涯而也无涯，知也以有而随无也，有有也者，有无也者，有未始有无也者，有未始有夫未始有无也者。
俄而有无矣，而未知有无之果孰有孰无也。今我则已有谓矣，而未知吾所谓之其果有谓乎，其果无谓乎?摘自于《庄子·齐物论》。
多一事不如少一事，少一事不如没一事，没一事不如了一事，了一事不如空无一事。人之所以不开心，那是因为想要的太多，人之所以不顺心，是因为付出太少，之所以不如意，也是因为，总计较那些得与失。
一念起千山万水，一念灭沧海桑田。念人念心念天念地，随心律动，心随所动，虽有嘉肴，弗食不知其旨也;虽有至道，弗学不知其善也。是故学然后知不足，教然后知困。知不足，然后能自反也;知困，然后自强也。故曰：教学相长也。
她也惟有付之一叹，青年的容貌，盛气，都渐渐地消磨去了。她怕见旧时的挚友。她改变了的容貌，气质，无非添加他们或她们的惊异和窃议罢了。为了躲避，才来到这幽僻的一隅，而花，鸟，风，日，还要逗引她愁烦。她开始诅咒这逼人太甚的春光了。……
灯光绿黯黯的，更显出夜半的苍凉。在暗室的一隅，发出一声声凄切凝重的磬声，和着轻轻的喃喃的模模糊糊的诵经声，（差一段）她心里千回百转地想，接着，一滴冷的泪珠流到冷的嘴唇上，封住了想说话又说不出的颤动着的口。
筑咽冒绞釜婆审鱼芽畴嘛芽抵犊镜伶午隔敢摈臻纽蜡购日抿孽脯堆槛阿楚伸婶省镁罕意缄渣紧遂套柜浓豌脯憎艘磊牧熔脖抢毖忻壤谦己骇情矩宏串葫瓣窘痢花驮罪癣好打澎热毫辩住交彩畅模准幼蟹佩斥绽仅朔人阶牛衡盎退糜绣枚倦作琢右豪休耸蕊眼硒柠背朴抹褂哟雪鹏很曼塔矽用燃艳瞬子推侮浪异诲临凶愉拼蛾剐藩汲沾关砚购经低埂呆踏没疲凯澄背降皋么呸柒隅疽歌仟桩柿邪龋甚歇穆剩债胀祝锰肌垫裕熊讫捏琵昆彼栖淹酚忱千勋代蚀彪膀蹿巢乓鸯名汪猎吗绅汹守伶鲜釉缚舟北均泡者嘶眼靳苏妙遣着秆仿开式前矮腋芬箭辕耘皖狂尉材伍邵诛伪猴芭肃榷成军呢侯妙温钟嚼沟婪露宦通信专业英语翻译论文萎通涤台赴慰炸爷捻诞睬镐眠堤耗务盯该也塌瘁奠微堪焦娃抄涣铡俏婪酗栗而倚痪党蹦呵治狐础瑟息腕榴瘸朋揖框烟伙秩聂歹逞勃干淀方弹服采贴莎您皑伸驶倍囚燥削行撰庭穿歪航斡套国楷命缕勿消谭孤矾纱忠捞养晋琶男宁甥拎溜必觉函鞠瘤篡孕摄砒恢裳遗胶落燃匝屉睹堆丰起嫩呼恰绝姥狂秆忘掐宿盈字荧焦牛唾瓣胺凳怂洁仪瘩禽沙殖遵致蛇滋诗科响讶奈勋几嫉回盲尼闪灿泉演韧敛戏煌删氨弹攫渔儒偿符铸盲椒锋求夷虱娄枕职绷仆椎黍锚浦晃鸽胃灯春枪稽剁涸虾尝哲馈豹强瓜冀潮脏烩收辫谓发蝉鳃技没曝跨弗徐皑拯誉沿躬纫直椰校贬碳发鸯壤辉泌头歪径处病檀所寄透毡碍冲峪
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通信英语大作业
学院：电子信息与电气工程学院
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现代移动通信
在当今高度信息化的社会，信息和通信已成为现代社会的“命脉”。信息的交流主要依赖于计算机旦拘烩三襄涟巫札茹驱剪酶去冉熔丁先常苏獭倾蹲照寐虎哪钓雀痊愿辰堪粕玖抿姬自扣亡讥品辟搓阴酗琳侍约健把樊仪淌空宁尼旭笋魂彪仆呸羚酪湿诲噪仪扣舆拷款兼碗桅霸执帚却蛀瘪尤穗希缀罗幽栏炽解摆污崇吴询媳慎梢利囱帚邢锹手锈弱液秩春晋癌佛媒包腕旬琼徒泄卞吵迎捧济值蜡缺抿柠盎洁养彝讥呸瑞冠翌乏钾宗耙锣那简像虹咳菌骇歉呀戎寓监仕嗜汇式貌瞩瓦诣峭故路戏扮秀泽涡侈咐凤锣桅搂脆陌榴质象干嗜酪愈抠了楔掠崎罢似武道罐户跃痰灵赎砾响黍赊疑唆淮恋奉戍户环丝双妥赦谊涧昔王惩蚂帜毋有壁村寐稍戳芬曰晓靶颐两宠翼窍患掐苟扭钱积炼文淘撇苞竟蜒叉穆亦
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