外文翻譯--超寬帶技術(shù)的短期或中期范圍內(nèi)的無(wú)線通信

1、外文翻譯-超寬帶技術(shù)的短期或中期范圍內(nèi)的無(wú)線通信 外文文獻(xiàn)原文Ultra-Wideband Technology for Short-or Medium-Range Wireless Communications Jeff Foerster, Intel Architecture Labs, Intel Corp Evan Green, Intel Architecture Labs, Intel Corp Srinivasa Somayazulu, Intel Architecture Labs, Intel Corp David Leeper, Intel Connected Produc

2、ts Division, Intel CorpIndex words: UWB, wireless, communications, LAN, PAN ABSTRACT Ultra-Wideband UWB technology is loosely defined as any wireless transmission scheme that occupies a bandwidth of more than 25% of a center frequency, or more than 1.5GHzThe Federal Communications Commission FCC is

3、currently working on setting emissions limits that would allow UWB communication systems to be deployed on an unlicensed basis following the Part 15.209 rules for radiated emissions of intentional radiators, the same rules governing the radiated emissions from home computers, for example. This rule

4、change would allow UWB-enabled devices to overlay existing narrowband systems, which is currently not allowed, and result in a much more efficient use of the available spectrumDevices could, in essence, fill in the unused portions of the frequency spectrum in any particular locationThese recent deve

5、lopments by the FCC give Intel a unique opportunity to develop equipment that could potentially take advantage of the vast amount of usable spectrum that exists in the wireless space, and that could provide an engine to drive the future high-rate applications that are being conceived throughout this

6、 industry Intel? Architecture Labs IAL is currently researching UWB technology in order to better understand its benefits, limitations, and technical challenges when used for high-rate communicationsThis paper introduces the reader to this technology, from potential applications to regulatory hurdle

7、s, to possible implementations and future challenges.INTRODUCTION Ultra-Wideband UWB technology has been around since the 1980s, but it has been mainly used for radar-based applications until now see 1 and the references therein, because of the wideband nature of the signal that results in very accu

8、rate timing information. However, due to recent developments in high-speed switching technology, UWB is becoming more attractive for lowcost consumer communications applications as detailed in the “Implementation Advantages” section of this paper. Intel Architecture Labs IAL is currently working on

9、an internally funded research project whose intent is to further explore the potential benefits and future challenges for extending UWB technology into the high-rate communications arena Although the term Ultra-Wideband UWB is not very descriptive, it does help to separate this technology from more

10、traditional “narrowband” systems as well as newer “wideband” systems typically referred to in the literature describing the future 3G cellular technology. There are two main differences between UWB and other “narrowband” or “wideband” systems. First, the bandwidth of UWB systems, as defined by the F

11、ederal Communications Commission FCC in 2, is more than 25% of a center frequency or more than 1.5GHzClearly, this bandwidth is much greater than the bandwidth used by any current technology for communication. Second, UWB is typically implemented in a carrierless fashion. Conventional “narrowband” a

12、nd “wideband” systems use Radio Frequency RF carriers to move the signal in the frequency domain from baseband to the actual carrier frequency where the system is allowed to operate. Conversely, UWB implementations can directly modulate an “impulse” that has a very sharp rise and fall time, thus res

13、ulting in a waveform that occupies several GHz of bandwidthAlthough there are other methods for generating a UWB waveform using a chirped signal, for example, in this paper, we focus on the impulse-based UWB waveform. but, first, a breakdown of how this paper is organized.WIRELESS ALTERNATIVES In or

14、der to understand where UWB fits in with the current trends in wireless communications, we need to consider the general problem that communications systems try to solve. Specifically, if wireless were an ideal medium, we could use it to send.1. a lot of data,2. very far,3. very fast,4. for many user

15、s,5. all at once.Unfortunately, it is impossible to achieve all five attributes simultaneously for systems supporting unique, private, two-way communication streams; one or more have to be given up if the others are to do well. Original wireless systems were built to bridge large distances in order

16、to link two parties together. However, recent history of radio shows a clear trend toward improving on the other four attributes at the expense of distanceCellular telephony is the most obvious example, covering distances of 30 kilometers to as little as 300 metersShorter distances allow for spectru

17、m reuse, thereby serving more users, and the systems are practical because they are supported by an underlying wired infrastructure? the telephone network in the case of cellular. In the past few years, even shorter range systems, from 10 to 100 meters, have begun emerging, driven primarily by data

18、applications. Here, the Internet is the underlying wired infrastructure, rather than the telephone network. Many expect the combination of short-range wireless and wired Internet to become a fast-growing complement to next generation cellular systems for data, voice, audio, and video. Four trends ar

19、e driving short-range wireless in general and ultra-wideband in particular:1. The growing demand for wireless data capability in portable devices at higher bandwidth but lower in cost and power consumption than currently available.2. Crowding in the spectrum that is segmented and licensed by regulat

20、ory authorities in traditional ways.3. The growth of high-speed wired access to the Internet in enterprises, homes, and public spaces.4. Shrinking semiconductor cost and power consumption for signal processing Trends 1 and 2 favor systems that offer not just high-peak bit rates, but high spatial cap

21、acity1 as well, where spatial capacity is defined as bits/sec/square-meter. Just as the telephone network enabled cellular telephony, Trend 3 makes possible high-bandwidth, in-building service provision to low-power portable devices using short-range wireless standards like Bluetooth /0>. and IEE

22、E 802.11 /. Finally, Trend 4 makes possible the use of signal processing techniques that would have been impractical only a few years ago. It is this final trend that makes Ultra-Wideband UWB technology practical. When used as intended, the emerging short- and medium-range wireless standards vary wi

23、dely in their implicit spatial capacities. For example :1.IEEE 802.11b has a rated operating range of 100 meters. In the 2.4GHz ISM band, there is about 80MHz of useable spectrum. Hence, in a circle with a radius of 100 meters, three 22MHz IEEE 802.11b systems can operate on a non-interfering basis,

24、 each offering a peak over-the-air speed of 11Mbps. The total aggregate speed of 33Mbps, divided by the area of the circle, yields a spatial capacity of approximately 1,000 bits/sec/square-meter2.Bluetooth, in its low-power mode, has a rated 10-meter range and a peak over-the-air speed of 1MbpsStudi

25、es have shown that approximately 10 Bluetooth “piconets” can operate simultaneously in the same 10-meter circle with minimal degradation yielding an aggregate speed of 10Mbps 3. Dividing this speed by the area of the circle produces a spatial capacity of approximately 30,000 bits/sec/square-meter3.I

26、EEE 802.11a is projected to have an operating range of 50 meters and a peak speed of 54Mbps. Given the 200MHz of available spectrum within the lower part of the 5GHz U-NII band, 12 such systems can operate simultaneously within a 50-meter circle with minimal degradation, for an aggregate speed of 64

27、8Mbps. The projected spatial capacity of this system is therefore approximately 83,000 bits/sec/square-meter4.UWB systems vary widely in their projected capabilities, but one UWB technology developer has measured peak speeds of over 50Mbps at a range of 10 meters and projects that six such systems c

28、ould operate within the same 10-meter radius circle with only minimal degradation. Following the same procedure, the projected spatial capacity for this system would be over 1,000,000 bits/sec/square-meter Current low data-rate Wireless Local Area Networks WLANs and Wireless Personal Area Networks W

29、PANs, which have data rates of 1-10Mbps, are typically used for applications such as packet-switched data and cordless voice telephony, using Time Division Multiple Access TDMA voice circuits. Example technologies supporting these applications are the IEEE 802.11b Wi-Fi*, Bluetooth?, and HomeRF* net

30、working standards. As the IEEE 802.11 and ETSI BRAN HiperLAN/2* standards the European equivalent of 802.11 have added physical layer specifications with raw data rates up to 54Mbps, the application space is enlarging to include audio/video applications that are enabled by these higher data rates. T

31、hese diverse traffic types all have different requirements in terms of the service parameters that quantify the network performance for a user of each of those applications. Thus, for example, voice telephony and video teleconferencing applications place tough demands on the latency and jitter perfo

32、rmance. Audio/video applications require large amounts of bandwidth and may need close synchronization e.g., connecting stereo speakers in a surround sound system. Ultra-Wideband UWB systems, with their potential for extremely large data rates over short distances, are naturally going to be used for

33、 networking these kinds of high-bandwidth/delaycritical data sources and sinks. Hence, it would be natural to look at the approaches to the MAC design undertaken in these other standards when considering the MAC layer design for UWB systemsThe most important functions of the MAC layer for a wireless

34、 network include controlling channel access, maintaining Quality of Service QoS, and providing security外文文獻(xiàn)翻譯超寬帶技術(shù)的短期或中期范圍內(nèi)的 無(wú)線通信杰夫福斯特,英特爾架構(gòu)實(shí)驗(yàn)室,英特爾公司埃文格林,英特爾架構(gòu)實(shí)驗(yàn)室,英特爾公司斯里尼瓦薩,英特爾架構(gòu)實(shí)驗(yàn)室,英特爾公司 大衛(wèi)利珀,英特爾部連接的產(chǎn)品,英特爾公司關(guān)鍵字:超寬帶,無(wú)線,通訊,局域網(wǎng),無(wú)源光網(wǎng)絡(luò)摘要 超寬帶(UWB)技術(shù)可以大致的被定義為一個(gè)占有超過(guò)25%中心頻率的帶寬,或者漲幅比為1.5GHz的帶寬的任何無(wú)線傳輸方案。美國(guó)聯(lián)邦

35、通訊委員會(huì)(FCC)目前正在制定措施限制超寬帶通信系統(tǒng)的輻射排放量,與家用電腦管理的輻射排放量相同,在無(wú)牌經(jīng)營(yíng)的基礎(chǔ)上部署第15.209有目的的散熱輻射規(guī)則。這一規(guī)則的改變將使UWB的可以啟用的頻譜更有效地利用現(xiàn)有的窄帶系統(tǒng)來(lái)覆蓋,并使得有用的頻譜更為有效,但目前這是不允許的。本質(zhì)上這些設(shè)備可以在任何特定地點(diǎn)頻譜的未使用的部分中使用。 通過(guò)FCC最近的這些發(fā)展給了英特爾一個(gè)獨(dú)特的機(jī)會(huì)來(lái)發(fā)展硬件設(shè)施,它們可以依靠存在于無(wú)線領(lǐng)域大量的潛在的優(yōu)勢(shì)來(lái)利用巨大的可用頻譜,而且正在提供一個(gè)用來(lái)驅(qū)動(dòng)未來(lái)的高速率應(yīng)用引擎的整個(gè)行業(yè)的構(gòu)思。 英特爾?架構(gòu)實(shí)驗(yàn)室(的IAL)目前正在研究超寬帶技術(shù),以更好地了解它的

36、好處、缺陷和使用高速率通信帶來(lái)的技術(shù)挑戰(zhàn)。本文從潛在的應(yīng)用程序的監(jiān)管障礙到可能的實(shí)現(xiàn)和未來(lái)的挑戰(zhàn)向讀者介紹了這項(xiàng)技術(shù)。 簡(jiǎn)介 寬帶(UWB)的技術(shù)流行于20世紀(jì)80年代,因?yàn)樾盘?hào)的寬帶性質(zhì)使它具有非常準(zhǔn)確的計(jì)時(shí)信息,使它僅用于基于雷達(dá)的應(yīng)用程序,然而由于在高速交換技術(shù)的最新發(fā)展,使UWB對(duì)于低成本的消費(fèi)通信應(yīng)用變得更加有吸引力的。英特爾架構(gòu)實(shí)驗(yàn)室(IAL)目前正在內(nèi)部資助研究項(xiàng)目,其目的是進(jìn)一步探討延伸到高速率通信領(lǐng)域超寬帶技術(shù)的潛在好處和未來(lái)的挑戰(zhàn)。 雖然短期超寬帶(UWB)不是很有說(shuō)服性,但它確實(shí)有助于從傳統(tǒng)的“窄帶”系統(tǒng)技術(shù)以及新的“寬帶”系統(tǒng)通常描述中提到的未來(lái)3G蜂窩技術(shù)中分離出這種

37、技術(shù)。UWB和其他“窄帶”或“寬帶”系統(tǒng)之間有兩個(gè)的主要區(qū)別。首先,超寬帶系統(tǒng)的帶寬,如美國(guó)聯(lián)邦通訊委員會(huì)(FCC)的定義,是25%以上的或超過(guò)1.5GHz的中心頻率。顯然,這種帶寬遠(yuǎn)遠(yuǎn)大于目前任何技術(shù)所采用的通信帶寬。其次,UWB是一個(gè)典型的實(shí)施載波方式。傳統(tǒng)的“窄帶”和“寬帶”系統(tǒng)使用無(wú)線電頻率(RF)基帶運(yùn)載在頻域中的信號(hào),并且這些系統(tǒng)允許被操作。相反,超寬帶的實(shí)現(xiàn)可以直接調(diào)節(jié)一個(gè)“脈沖”,這種脈沖有一個(gè)非常尖銳的上升和下降時(shí)間,因此,在占用的波形產(chǎn)生幾個(gè)GHz的帶寬。雖然產(chǎn)生一個(gè)UWB波形有許多其他的方法,但在本文中,我們著重?cái)⑹雒}沖的超寬帶波形。無(wú)線替代的手段 為了了解在無(wú)線通信中超

38、寬帶無(wú)線通信適用于哪些目前的趨勢(shì),我們需要考慮一般通信系統(tǒng)試圖解決的問(wèn)題。尤其是,如果無(wú)線是一個(gè)理想的媒介,可以用它來(lái)傳送 1.大量的數(shù)據(jù),2.遠(yuǎn)距離傳輸,3.傳輸速度快,4.多用戶,5.同時(shí)性。 不幸的是,不可能尋在實(shí)現(xiàn)一個(gè)同時(shí)具備這五種特性的通信和雙向通信流系統(tǒng),如果其他的要做好,必須放棄一個(gè)或多個(gè)特性。原來(lái)的無(wú)線系統(tǒng)用于測(cè)量大型橋梁的距離,以便使雙方聯(lián)系在一起。然而,最近的一個(gè)無(wú)線電歷史顯示了對(duì)于其他四個(gè)屬性的距離費(fèi)用存在明顯提高的趨勢(shì)。蜂窩電話系統(tǒng)就是最明顯的例子,覆蓋300米到30公里的范圍。短距離允許頻譜再利用,從而服務(wù)更多的用戶,并且系統(tǒng)是可行的,因?yàn)樗鼈兪怯梢粋€(gè)基本的有線基礎(chǔ)設(shè)施中的移動(dòng)電話網(wǎng)絡(luò)來(lái)支撐的。在過(guò)去數(shù)年,甚至更短距離系統(tǒng),從10到100米,已經(jīng)開(kāi)始出現(xiàn),帶動(dòng)了以數(shù)據(jù)應(yīng)用為主。在這里,有線互聯(lián)網(wǎng)是基礎(chǔ)設(shè)施,而不是電話網(wǎng)絡(luò)。許多人期待短距離無(wú)線和有線互聯(lián)網(wǎng)結(jié)合成一個(gè)快速增長(zhǎng)的補(bǔ)充數(shù)據(jù),語(yǔ)音,音頻和視頻的下一代的蜂窩系統(tǒng)。四大趨勢(shì)正在推動(dòng)短距離尤其是超寬帶無(wú)線通信的普及:1對(duì)于無(wú)線數(shù)據(jù)能力的便攜式設(shè)備日益增加的對(duì)高帶寬需求,以及低于目前可用技術(shù)的成本和功耗。(2)擁擠的頻譜分割卻以傳統(tǒng)的方式被監(jiān)管部門(mén)分段和控制。(3)高速有線接入的企業(yè),家庭上網(wǎng)速度,和公共空間的增長(zhǎng)