通信專業(yè)英語翻譯論文.doc

本文由宏哥1015貢獻 doc文檔可能在WAP端瀏覽體驗不佳。建議您優(yōu)先選擇TXT，或下載源文件到本機查看。 現(xiàn)代移動通信 在當(dāng)今高度信息化的社會，信息和通信已成為現(xiàn)代社會的“命脈” 。信息的 交流主要依賴于計算機通信，而通信作為傳輸手段，與傳感技術(shù)、計算機技術(shù)相 互融合，已成為 21 世紀國際社會和世界經(jīng)濟發(fā)展的強大動力。為了適應(yīng)時代的 要求，新的一代移動通信技術(shù)應(yīng)時而生，新的一代移動通信技術(shù)即人們稱之第三 代的核心特征是寬帶尋址接入到固定網(wǎng)和眾多不同通信系統(tǒng)間的無隙縫漫游， 獲 取多媒體通信業(yè)務(wù)。 隨著時代的進步、科技的創(chuàng)新、人們的生活要求的提高，移動通信技術(shù)更新 換代速度相當(dāng)驚人，差不多每隔十年移動通信技術(shù)就發(fā)生一次變革性換代，從上 個世紀 80 年代的“大哥大”到現(xiàn)在的 3G 手機，其間發(fā)生了兩次移動通信技術(shù)的 變革，從 1G 的 AMPS 過渡到 2G 的 GSM，從 GSM 到 IMT-2000（即 3G 技術(shù)） 。就我 所知現(xiàn)代的移動通信技術(shù)有以下幾方面的重要技術(shù)： 1.寬帶調(diào)制和多址技術(shù) 無線高速數(shù)據(jù)傳輸不能一味僅靠頻譜的擴展， 應(yīng)在頻譜效率上至少高于目前 一個數(shù)量級，可在物理層采用三項技術(shù)，即 OFDM、UWB 和空時調(diào)制編碼。OFDM 與其他編碼方式的結(jié)合，靈活把 OFDM 與 TDMA、FDMA、CDMA、SDMA 組合成多址技 術(shù)。 20 世紀 60 年代 OFDM 的多路數(shù)據(jù)傳輸已成功用于 Kineplex 和 Kathryn 高頻 軍事通信系統(tǒng)。OFDM 已用于 1.6 Mbit/s 高比特率數(shù)字用戶線（HDSL） Mbit/s ，6 不對稱數(shù)字用戶線（ADSL） ，100 Mbit/s 甚高速數(shù)字用戶線（VDSL） ，數(shù)字音頻 廣播和數(shù)字視頻廣播等。OFDM 應(yīng)用于 5 GHz 上提供 54 Mbit/s 無線本地網(wǎng) IEEE 802.11 a 和 IEEE 802.11g，高性能本地域網(wǎng)絡(luò) Hiper LAN/2 和 ETSI-BRAN，還 作為城域網(wǎng) IEEE 802.16 和集成業(yè)務(wù)數(shù)字廣播（ISDB-T）標(biāo)準。與單載頻調(diào)制制 式相比， OFDM 調(diào)制制式要解決相對大的峰均功率比 （PAPR， Peak to Average Power Ratio）和對頻率位移和相位噪聲敏感的問題。 高速移動通信的另一要求是在寬噪聲帶寬下，所需解調(diào)信噪比應(yīng)盡可能降 低，從而增加覆蓋面積?？刹扇】顾ヂ涞目焖侔l(fā)射功率控制和導(dǎo)頻輔助快速跟蹤 相干解調(diào)技術(shù)，如頻域抗衰落的 Rake 接收和跟蹤技術(shù)，從時域和頻域抵抗時間 和頻率選擇性衰落的 OFDMA 技術(shù)，鏈路自適應(yīng)技術(shù)，聯(lián)合編碼技術(shù)。 1 2.頻譜利用率提升技術(shù) 理論研究指出：在獨立 Rayleigh 散射信道中，數(shù)據(jù)速率與天線數(shù)成線性關(guān) 系，容量可達 Shannon 的 90%。在發(fā)射和接收端以多天線開發(fā)信道空間可取得容 量和頻譜效率的增益。MIMO 技術(shù)主要包括空間復(fù)用和空間分集技術(shù)，在獨立信 道上并發(fā)或連發(fā)相同信息來提高傳輸可靠性。 收發(fā)雙方的空間分集是高容量無線通信系統(tǒng)采用技術(shù)之一。 貝爾實驗室分層 次空時的對角 BLAST（D-BLAST）容量的增加為收發(fā)雙方最小天線數(shù)的函數(shù)。利 用 MIMO 所構(gòu)成的跨時域和空域的擴展信號還可以抵抗多徑干擾。V-BLAST 系統(tǒng) 在室內(nèi) 2434 dB 時，頻譜利用率為 2040 bit/s/Hz。而發(fā)射和接收端均采用 16 天線，在 30 dB 時，頻譜利用率增至 6070 bit/s/Hz。 智能天線自動跟蹤所需信號和自適應(yīng)空時處理算法， 利用天線陣產(chǎn)生空間定 向波束，通過數(shù)字信號處理技術(shù)使主波束對準用戶信號到達方向，旁瓣或零陷對 準干擾信號到達方向。自適應(yīng)陣列天線（AAA，Adaptive Array Antennas）中干 擾抵消均衡器（ICE，Interference Canceling Equalizer）可減少干擾和降低 發(fā)射功率。 3.軟件無線電技術(shù) 軟件無線電技術(shù)是在硬件平臺上通過軟件編輯以一個終端實施不同系統(tǒng)中 多種通信業(yè)務(wù)。它用數(shù)字信號處理語言描述電信元件，以軟件程序下載成數(shù)字信 號處理硬件（DSPH，Digital Signal Pocessing Hardware） 。以具有通用開放無 線結(jié)構(gòu)（OWA，Open Wireless Architecture） ，兼容多種模式在多種技術(shù)標(biāo)準之 間無縫切換。 UWB 也稱為脈沖無線電，調(diào)制采用脈沖寬度在納秒級的快速上升和下降脈 沖，脈沖覆蓋的頻譜從直流至吉赫茲，不需常規(guī)窄帶調(diào)制所需的射頻上變換，脈 沖成型后可直接送至天線發(fā)射。 4.軟件無線電技術(shù) 軟件無線電技術(shù)是在硬件平臺上通過軟件編輯以一個終端實施不同系統(tǒng)中 多種通信業(yè)務(wù)。它用數(shù)字信號處理語言描述電信元件，以軟件程序下載成數(shù)字信 號處理硬件（DSPH，Digital Signal Pocessing Hardware） 。以具有通用開放無 線結(jié)構(gòu)（OWA，Open Wireless Architecture） ，兼容多種模式在多種技術(shù)標(biāo)準之 2 間無縫切換。 5.網(wǎng)絡(luò)安全和 QoS QoS 分為無線和有線側(cè)兩部分，無線側(cè)的 QoS 涉及無線資源管理和調(diào)度，接 納控制和移動性管理等，移動性管理主要包括終端移動性，個人移動性和業(yè)務(wù)移 動性。有線側(cè)的 QoS 涉及基于 IP diffSer 的區(qū)分業(yè)務(wù)和 RSVP 的端到端資源預(yù)留 機制。把 IP diffSer 的 IP QoS 機制映射到無線側(cè)。網(wǎng)絡(luò)安全包括網(wǎng)絡(luò)接入安全， 核心網(wǎng)安全，應(yīng)用安全，安全機制可見性與可配置性。 在上述現(xiàn)代移動通信關(guān)鍵技術(shù)的基礎(chǔ)上，產(chǎn)生了陸地蜂窩移動通信、衛(wèi)星通 信以及無線因特網(wǎng)通信技術(shù)，這些通信方式使通信面貌發(fā)生了巨大的變化，采用 數(shù)字技術(shù)的現(xiàn)代無線通信已經(jīng)滲入國民經(jīng)濟的各個領(lǐng)域和人們的日常生活，為 此， 我們需要關(guān)心它的發(fā)展趨勢， 希望它朝著越來越方便人們的生活的方向發(fā)展， 現(xiàn)在就讓我們來看看現(xiàn)代移動通信的未來發(fā)展趨勢吧。 現(xiàn)代移動通信技術(shù)發(fā)展的七個新趨勢: 一、移動管理已從終端管理向個人管理和智能管理發(fā)展 二、 網(wǎng)絡(luò)已從同步的數(shù)字電路向異步的數(shù)字分組和異步傳遞方式(ATM)發(fā)展; 三、軟件的開發(fā)已從算法驅(qū)動到面向過程和面向目標(biāo)的趨勢發(fā)展; 四、信息處理已從話音發(fā)展到數(shù)據(jù)和圖像; 五、無線頻譜的處理已從窄帶模擬向窄帶 CDMA 發(fā)展; 六、計算機已從集中式處理發(fā)展到分布式服務(wù)器和智能化處理; 七、半導(dǎo)體器件已從每芯片 16 兆門/150MHz 速率的 VLSI 發(fā)展到 0.5 千兆門 /350MHz 速率的 VLSI 和 2 千兆門 /550MHz 速率的 VLSI。 在這種趨勢的引導(dǎo)下，移動通信業(yè)務(wù)迅猛發(fā)展，它滿足了人們在任何時間、 任何地點與任何個人進行通信的愿望。 移動通信是實現(xiàn)未來理想的個人通信服務(wù) 的必由之路。在信息支撐技術(shù)、市場競爭和需求的共同作用下，移動通信技術(shù)的 發(fā)展更是突飛猛進，呈現(xiàn)出以下幾大趨勢：1)網(wǎng)絡(luò)業(yè)務(wù)數(shù)據(jù)化、分組化；2)網(wǎng)絡(luò) 技術(shù)寬帶化；3)網(wǎng)絡(luò)技術(shù)智能化；4)更高的頻段；5)更有效利用頻率；6)各種網(wǎng) 絡(luò)趨于融合。了解、掌握這些趨勢對移動通信運營商和設(shè)備制造商均具有重要的 現(xiàn)實意義。 3 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 generations core characteristic is the wide band addressing turns on non-gap roaming between the rigid network and numerous different communications systems, gains the multimedia communication services. Along with the time progress, the technical innovation, peoples life requests 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 presents 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 methods union, nimbly OFDM and TDMA, FDMA, CDMA, SDMA combines the multiple access technique. 4 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 subscribers 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 communications 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-fadings 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 5 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 times 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 2434 dB, the frequency spectrum use factor is 2040 bit/s/Hz. But launches and the receiving end uses 16 antennas, when 30 dB, the frequency spectrum use factor increases to 6070 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 Array 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, 6 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 sides 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 sides 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 technologiess foundation, has had the land honeycomb mobile communication, the 7 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 peoples daily life, for this reason, we needed to care that its trend of development, hoped it developed toward more and more convenient peoples lifes 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, softwares 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;