羅強通信專業(yè)英語大作業(yè)

1、.； 通信專業(yè)英語大作業(yè)姓 名： 羅強 學 號： 201230105089 序 號： 01號 系 別： 中興通信工程學院 班 級： 12級通信六班 完成時間： 2014、12、26 一、 翻譯4G Mobile:4G MobileVoice was the driver for second-generation mobile and has been a considerable success.Today,video and TV services are driving forward third generation (3G) deployment. And in the future

2、, low cost, high speed will drive forward the fourth generation (4G) as short-range communication emerges. Service and a plication ubiquity,with a high degree personalization and synchronization between various user appliances, will be another driver. At the same time, it is probable that the radio

3、access network will evolve from a centralized architecture to a distributed one.聲音是第二代移動驅動，并得到了相當大的成功。今天，視頻和TV服務正在向第三代（3G）發(fā)展。并且在以后，低成本和高速的特點將帶動它們進入第四代（4G）即短距離通信，隨著服務和折疊技術的普及，各種用戶設備之間的個性化和同步化程度越高，將成為另一個驅動器。在同一時間，該無線電接入網絡有可能將來自集中式架構演進到一個分布式之一。1 .Service EvolutionThe evolution from 3G to 4G will be dri

4、ven by services that offer better quality(e.g.,video and sound) thanks to greater bandwidth, more sophistication in the association of a large quantity of information, and improved personalization. Convergence with other network (enterprise,fixed) services will come about through the high session da

5、ta rate. It will require an always-on connection and a revenue model based on a fixed monthly fee. The impact on network capacity is expected to be significant. Machine-to-machine transmission will involve two basic equipment types: sensor (which measure parameters)and tags (which are generally read

6、/write equipment).It is expected that users will require high data rates,similar to those on fixed networks,for data and streaming applications. Mobile terminal usage (laptops, personal digital assistants, handhelds) is expected to grow rapidly as they become more user friendly. Fluid high quality v

7、ideo and network reactivity are important user requirements. Key infrastructure design requirements include: fast response, high session rate, high capacity, low user charges, rapid return on investment for operators, investment that is line with the growth in demand, and simple autonomous terminals

8、.The infrastructure will be much more distributed than in current deployments, facilitating the introduction of a new source of local traffic: machine-to-machine.1服務革命從3G到4G演進將由更高質的服務（例如，視頻和聲音）推動，更大的帶寬使得大量信息的關聯顯得更加復雜，個人化也得到了提高。要想融合了其他網絡（企業(yè)，固定的）服務的出現得通過高會話的數據速率。這將需要一個永遠在線的連接，并收取固定的月租費。預計這對網絡容量的影響是顯著。

9、機器間的傳輸將涉及兩個基本類型的設備：傳感器（用來測量參數）和標簽（通常用來讀/寫設備）。據估計，用戶會需要高數據速率，類似于那些在固定網絡提供數據和數據流的應用程序。移動終端的使用（筆記本電腦，個人數字助理，掌上電腦）有望迅速增長，因為它們變得更加方便用戶。流暢高質的的視頻和網絡的反應性是重要的用戶需求。關鍵基礎設施的設計要求包括：快速響應，高會話率，高容量，低使用費，運營商投資的快速回報。投資能夠按照需求的增長，以及簡單的自發(fā)終端?；A設施將比目前的部署更加分散，這樣便于引進本地通話的新來源：機器對機器。2 .Multi-technology Approach Many technolog

10、ies are competing on the road to 4Q,as can be seen in Figure 1.Three paths are possible, even if they are more or less specialized. The first is the 3G-centric path, in which Code Division Multiple Access (CDMA) will be progressively pushed to the point at which terminal manufacturers will give up.

11、When this point is reached, another technology will be needed to realize the required increases in capacity and data rates. The second path is the radio LAN one. Widespread deployment of WiFi is expected to start in 2005 for PCs, laptops and PDAs. In enterprises, voice may start to be carried by Voi

12、ce over Wireless LAN (VoWLAN). However, it is not clear what the next successful technology will be. Reaching a consensus on a 200 Mbit/s (and more) technology will be a lengthy task, with too many proprietary solutions on offer. A third path is IEEE 802.16e and 802.20, which are simpler than 3G for

13、 the equivalentperformance. A core network evolution towards a broadband Next Generation Network (NGN) will facilitate the introduction of new access network technologies through standard access gateways,based on ETSI-TISPAN, ITU-T, 3GPP, China Communication Standards Association (CCSA) and other st

14、andards. How can an operator provide a large number of users with high session data rates using itsexisting infrastructure? At least two technologies are needed. The first (called parent coverage) is dedicated to large coverage and real-time services. Legacy technologies, such as 2G/3G and their evo

15、lutions will be complemented by WiFi and WiMAX. A second set of technologies is needed to increase capacity, and can be designed without any constraint on coverage continuity. This is known as pico-cell coverage. Only the use of both technologies can achieve both targets.Handover between parent cove

16、rage and pico cell coverage is different from a classical roaming process, but similar to coverage handover.Parent cover can also be used as a back-up when service delivery in the pico cell become too difficult.2多技術方法如在圖1可以看出，許多技術都在4Q的道路上爭奪著，.有三種路徑是可能的，即使它們或多或少專門化。第一種路徑是3G中心，其中碼分多址（CDMA）將逐步被推到終端制造商放

17、棄的狀態(tài)下。當達到這一狀態(tài)，另一種技術，將需要實現所需容量的增加和數據傳輸速率。第二種路徑是無線局域網之一。廣泛部署的WiFi，預計從2005年開始使用在個人電腦，筆記本電腦和PDA。在企業(yè)中，語音可能會開始通過無線局域網語音（VoWLAN）進行。然而，下一種成功的技術是不明確的。提供太多專有的解決方案，達到200 Mbit / s（以上）的技術達成共識將是一個漫長的任務。第三種路徑是IEEE802.16e和802.20，在相同性能下比3G技術更簡單了。對寬帶的下一代網絡（NGN）核心網絡演進將有利于通過標準的接入網關推出新的接入網技術，這是基于ETSI-TISPAN，ITU-T，3GPP，中

18、國通信標準化協(xié)會（CCSA）等標準?？墒褂貌僮髡咛峁┐罅渴褂弥F有的基礎設施有著高速度會話數據傳輸速率的用戶呢？至少需要兩種技術。第一種（稱為“父覆蓋”）是專用于大覆蓋范圍和實時服務。傳統(tǒng)技術，比如2G / 3G和它們的演進將由WiFi和WiMAX來補充。第二種技術是用來增加容量，并且可以被設計成沒有覆蓋連續(xù)性的任何約束。這就是所謂的皮蜂窩區(qū)覆蓋。只有采用這兩種技術才可實現目標。交接技術在父覆蓋和皮蜂窩區(qū)上，與傳統(tǒng)的漫游過程中不同，但在交接覆蓋相似。當皮蜂窩區(qū)服務提供變得過于困難時，父覆蓋還起到一種后備作用。3 .Key 4G TechnologiesSome of the key techn

19、ologies required for 4G are briefly described below:一些4G所需的關鍵技術簡述如下：3.1 OFDMAOrthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for physical layer performance, but also a framework for improving layer 2 performance by proposing an additional degree of free-dom. Usin

20、g ODFM, it is possible to exploit the time domain, the space domain, the frequency domain and even the code domain to optimize radio channel usage. It ensures very robust transmission in multi-path environments with reduced receiver complexity. As shown in Figure 2, the signal is split into orthogon

21、al subcarriers, on each of which the signal is narrowband (a few kHz) and therefore immune to multi-path effects, provided a guard interval is inserted between each OFDM symbol. OFDM also provides a frequency diversity gain, improving the physical layer performance. It is also compatible with other

22、enhancement technologies, such as smart antennas and MIMO. OFDM modulation can also be employed as a multiple access technology (Orthogonal Frequency Division Multiple Access; OFDMA). In this case, each OFDM symbol can transmit information to/from several users using a different set of subcarriers (

23、sub-channels). This not only provides additional flexibility for resource allocation (increasing the capacity), but also enables cross-layer optimization of radio link usage. 3.1正交頻分多址正交頻分復用（OFDM）不僅擁有針對物理層性能的明顯優(yōu)勢，同時擁有通過附加的自由程度來提高2層性能的這樣一個框架。使用ODFM，能夠利用時域，空間域，頻域和代碼域來優(yōu)化無線電信道的使用情況。它確保了在多徑環(huán)境下通過降低接收器的復雜性

24、來進行有效的傳輸。如圖2，該信號被分成正交子載波，對每一個所述信號是“窄帶”（幾kHz），因此不受多路徑的影響，OFDM提供插入每個OFDM符號之間一個保護間隔以及頻率分集增益用來提高物理層性能。OFDM也與其他增強技術兼容，例如智能天線和MIMO。也可以把OFDM調制作為一種多址技術（正交頻分多址; OFDMA）。在這種情況下，每個OFDM符號可以傳輸由多個用戶所使用的不同的子載波集合（子信道）的信息。這不僅提供了對資源分配（增加容量）的更多的靈活性，而且還優(yōu)化無線電鏈路的跨層使用。 3.2 Software Defined Radio Software Defined Radio (SDR

25、) benefits from todays high processing power to develop multi-band, multi-standard base stations and terminals. Although in future the terminals will adaptthe air interface to the available radio access technology, at present this is done by the infrastructure. Several infrastructure gains are expec

26、ted from SDR. For example, to increase network capacity at a specific time (e.g.，during a sports event), an operator will reconfigure its network adding several modems at a given Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G systems, SDR will become an ena

27、bler for the aggregation of multi-standard pico/micro cells. For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing.3.2軟件無線電軟件無線電（SDR）受益于當今的高處理能力所帶來的多頻段，多標準基站和終端的發(fā)展。雖然在未來

28、該終端將適應可用無線接入的空中接口技術，但是目前這項技術只在基礎設施實現。一些基礎設施預計會從SDR技術獲益。例如，為了在特定的時間提高網絡容量，（例如體育賽事期間）操作員將重新配置其網絡，在一個給定的基站收發(fā)臺（BTS）加入幾個調制解調器。SDR簡化了這個的重新配置。在4G系統(tǒng)的背景下，SDR將推動多標準微蜂窩的聚集。對于制造商，這可能是一個有力的援助，以提供多標準，多頻段設備，降低了開發(fā)難度，同時通過多頻道的處理減少費用。3.3 Multiple-Input Multiple-Output(MIMO)MIMO uses signal multiplexing between multipl

29、e transmitting antennas (space multiplex) and time or frequency. It is well suited to OFDM, as it is possible to process independent time symbols as soon as the OFDM waveform is correctly designed for the channel. This aspect of OFDM greatly simplifies processing. The signal transmitted by mantennas

30、 is received by nantennas. Processing of the received signals may deliver several performance improvements: range, quality of received signal and spectrum efficiency. In principle, MIMO is more efficient when many multiple path signals are received. The performance in cellular deployments is still s

31、ubject to research and simulations. However, it is generally admitted that the gain in spectrum efficiency is directly related to the minimum number of antennas in the link.3.3多輸入多輸出（MIMO）MIMO使用多個發(fā)送天線（空間復用）和時間或頻率之間的信號多路復用。它非常適合于OFDM中，因為它是能夠盡快將OFDM波形設計正確的信道處理獨立的時間符號。 OFDM的這一方面極大地簡化了處理。接收nantennas由man

32、tennas發(fā)送的信號。所接收的信號的處理可以提供幾個性能的改進：范圍，接收到的信號和頻譜效率的質量。原則上，MIMO是更有效時收到了許多多徑信號。蜂窩部署的性能仍然受到研究和模擬。然而，人們普遍承認，在頻譜效率增益是直接關系到天線中的鏈路的最小數目。3.4 Handover and Mobility Handover technologies based on mobile IP technology have been considered for data and voice.Mobile IP techniques are slow but can be accelerated wit

33、h classical methods (hierarchical, fast mobile IP). These methods are applicable to data and probably also voice. In single-frequencynetworks, it is necessary to reconsider the handover methods. Several techniques can be used when the carrier to interference ratio is negative (e.g. VSFOFDM, bit repe

34、tition), but the drawback of these techniques is capacity. In OFDM, the same alternative exists as in CDMA, which is to use macro-diversity. In the case of OFDM, MIMO allows macro-diversity processing with performance gains. However, the implementation of macro-diversity implies that MIMO processing

35、 is centralized and transmissions are synchronous. This is not as complex as in CDMA, but such a technique should only be used in situations where spectrum is very scarce.3.4交接和移動基于移動IP技術的切換技術被認為是用于數據和語音。移動 IP技術是緩慢的，但可以通過傳統(tǒng)方法（層次，快速移動IP）加速。這些方法適用于數據，可能也適用于語音。在單頻網絡中，考慮切換的方法是有必要的。當載波干擾比是負數的，這幾種技術可運用在此（

36、例如VSFOFDM，比特重復），但這些技術的缺點是容量的問題。在OFDM中，相同形式存在于CDMA，這是使用宏分集。在OFDM的情況下，MIMO允許具有性能增益宏分集的處理。然而，宏分集的實施意味著MIMO處理是集中式和傳輸是同步的。在CDMA中這沒那么復雜，但這樣的技術只能在頻譜是十分有限的情況下使用。4. Caching and Pico Cells Memory in the network and terminals facilitates service delivery. In cellular systems, this extends the capabilities of t

37、he MAC scheduler, as it facilitates the delivery of real-time services. Resources can be assigned to data only when the radio conditions are favorable. This method can double the capacity of a classical cellular system. In pico cellular coverage, high data rate (non-real-time) services can be delive

38、red even whenreception/transmission is interrupted for a few seconds. Consequently, the coverage zone within which data can be received/transmitted can be designed with no constraints other than limiting interference. Data delivery is preferred in places where the bit rate is a maximum. Between thes

39、e areas, the coverage is not used most of the time, creating an apparent discontinuity. In these areas, content is sent to the terminal cache at the high data rate and read at the service rate. Coverages are discontinuous. The advantage of coverage, especially when designed with caching technology,

40、is high spectrum efficiency, high scalability (from 50 to 500 bit/s/Hz), high capacity and lower cost. A specific architecture is needed to introduce cache memory in the network. At the entrance of the access network, lines of cache at the destination of a terminal are built and stored. When a termi

41、nal enters an area in which a transfer is possible, it simply asks for the line of cache following the last received between the terminal and the cache. A simple, robust and reliable protocol is used between the terminal and the cache service delivered in this type of coverage.4.緩存和微蜂窩在網絡和終端內存中有利于提供

42、服務。在蜂窩系統(tǒng)中，這擴展了MAC調度器的功能，因為它有助于實時服務的遞送。資源被分配到的數據僅對無線電的情況有利。這種方法可以加倍經典蜂窩系統(tǒng)的容量。在微蜂窩覆蓋下，高數據速率（非實時）服務可以輸送即使接收/發(fā)送器中斷幾秒鐘。因此，發(fā)送在覆蓋范圍區(qū)域內的可以被接收和傳輸數據可設計成沒有約束不同于限制性的干擾。數據被認為在比特率最大的地方遞送比較好。在這些區(qū)域之間的覆蓋并不使用大部分時間來產生一個明顯的不連續(xù)性。在這些領域中，內容會以高數據速率和讀取服務速率發(fā)送到終端的緩存。覆蓋范圍是“不連續(xù)的”。覆蓋的特別優(yōu)勢在于緩存技術的設計：高頻譜效率，高可擴展性（從50到500比特/秒/赫茲），高容量和更低的成本。一個具體的架構，需要在網絡中引入高速緩沖存儲器。在接入網口，建造和儲存終端的目標行緩存。當終端進入一個可以傳輸的區(qū)域，它會簡單地請求高速緩存的以下的終端和高速緩存之間最后的一次接收。一個簡單的，堅固的，可靠的協(xié)議被用于在終端和在這種類型的覆蓋輸送的緩存服務之間。2、 請找出最前沿技術中涉