通信工程专业英语结课论文中英.doc

通信工程专业英语结课论文(中英) 作者： 日期：2 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. 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. 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 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, 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. 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 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; 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 tendencys 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 technologys 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. 英译中： 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。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2434 dB时，频谱利用率为2040 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6070 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 Array Antennas）中干扰抵消均衡器（ICE，Int