超寬帶技術與其它短距離無線通信技術的比較

1、超寬帶技術與其它短距離無線通信技術的比較隨著個人通信消費電子產(chǎn)業(yè)的迅猛開展， 短距離無線通信領域的各種新技 術、 新方法層出不窮，朝著更快、更方便、更平安有效等方面進行開展。新的技術在 Intel 接入、信息家電、移動辦公、工業(yè)化等各個領域得到了廣泛的運用。其中，超寬帶 Ultra Wide Band, UWB 技術是在 20世紀 90年代以后開展起 來的一 種具有巨大開展?jié)摿Φ男滦蜔o線通信技術，被列為未來通信的十大技術之O1 超寬帶無線通信1.1 超寬帶技術簡介UWB Ultra Wideband,超寬帶技術是日前正被廣泛研究的一種新興無線通信技術，現(xiàn)在已經(jīng)成為高速無線個人網(wǎng) WPAN 的首

2、選技術。UWB 是指信號帶寬大于 500MHz 或者是信號帶寬與中心頻率之比大于 25%的 通信技術。與常見的通信方式使用連續(xù)的載波不同， UWB 中使用的無線信號中心 頻率為4.1GHz,帶寬為1. 4GHz瀕譜X圉很寬，但是發(fā)射功率非常低。通信速 度 在250Kbit? 10Mbit/秒之間。在250Kbit/秒的傳輸速度下可確保30m的通信 距離。 在短距離13m以下有很大優(yōu)勢，最高傳輸速度可達lGb/S。而傳統(tǒng) 的窄帶技術在長距離、低速傳輸具有優(yōu)勢。超寬帶UWB技術最初是面向雷達應用來開發(fā)的，一般認為它屬于一種無 載波通信技術。2002年2月，美國聯(lián)邦通信委員會 FCC正式將其解禁。L

3、I前 超寬帶 UWB 技術正被整合進家庭影院和便攜式產(chǎn)品，主要用于視頻和音頻信號的無線發(fā)送。寬帶UWB自問世后一直被看作是藍牙技術的替代品，與其他無線技術如 WLAN 、藍牙等相比，超寬帶 UWB 具有低功耗、高帶寬、 低 復雜度、低本錢的優(yōu)點，完全可以滿足短距離家庭娛樂應用需求。 1.2 超寬 帶性 能特點。超寬帶無線通信是一種與傳統(tǒng)技術有很大不同的無線通信技術。它能夠?qū)崿F(xiàn) 無線局域網(wǎng) LAN 和個人區(qū)域網(wǎng) PAN 中無線接口的互聯(lián)和接入。 UWB 具有以下特 占?八、?1 抗干擾性能強UWB 信號，在發(fā)射時將微弱的無線電脈沖信號分散在寬闊的頻帶中，輸出功 率甚至低于普通設備產(chǎn)生的噪聲。接收

4、時將信號能量復原出來，在解擴過程中產(chǎn) 生擴頻增益。因此，與 IEEE 802. 11a 、IEEE 802. lib 和藍牙相比，在同等碼速 條 件下， UWB 具有更強的抗干擾性。2) 傳輸速率高UWB 以非常寬的頻率帶寬來換取高速的數(shù)據(jù)傳輸， 并且不單獨占用現(xiàn)在已經(jīng) 擁擠不堪的頻率資源，而是共享其他無線技術使用的頻帶。其數(shù)據(jù)速率可以到達 兒十兆比特每秒到兒百兆比特每秒，有望高于藍牙 100倍，也可以高于 IEEE 802. 11a 和 IEEE 802. llbo3) 帶寬極寬UWB 使用的帶寬在 1GHz 以上，高達兒吉赫茲，并且可以和口前的窄帶通信 系統(tǒng)同時丄作而互不干擾。 這在頻率資

5、源日益緊 X 的今天開辟了一種新的時域無 線電資源。4) 頻譜利用率高，系統(tǒng)容量大因為不需要產(chǎn)生正弦載波信號， 可以直接發(fā)射沖激序列， 因而 CWB 系統(tǒng)具 有 很寬的頻譜和很低的平均功率， 有利于與其他系統(tǒng)共存， 從而提高頻譜利用率 , 帶 來了極大的系統(tǒng)容量。5) 功率低UWB 系統(tǒng)使用間歇的脈沖來發(fā)送數(shù)據(jù)，脈沖持續(xù)時間很短，一般在0. 20ns?l.ons 之間，有很低的占空因數(shù)，系統(tǒng)耗電可以做到很低，在高速通信時系統(tǒng)的耗電量僅為兒白口 W? 兒十 mwo 同時山于 UWB 系統(tǒng)信號的擴頻處理增益比較 大， 即使采用低增益的全向天線發(fā)射，也可使用小于 lmW 的發(fā)射功率實現(xiàn)兒千 米的 通

6、信。6) 平安性好UWB 平安性表現(xiàn)在兩方面： 一方面是采用跳時擴頻， 接收機只有發(fā)送端 擴頻碼時才能解出發(fā)射數(shù)據(jù)；另一方面是系統(tǒng)的發(fā)射功率譜密度極低。有用信息 完全淹沒在噪聲中，被截獲概率很小，被檢測的概率也很低，用傳統(tǒng)的接收機無 法接收。2 Wi-Fi 2. 1 Wi-Fi 技術簡介Wi-Fi (Wireless Fidelity, 無線高保真 ) 也是一種無線通信協(xié)議 , 正式名 稱是 IEEE802. llboWi-Fi 是以太網(wǎng)的一種無線擴展，肌 -Fi 網(wǎng)絡可以使用來互連電腦上互連 網(wǎng)。Wi-Fi網(wǎng)絡在無執(zhí)照的2.4和5千兆Hz的無線電頻帶經(jīng)營，數(shù)據(jù)速率 可達11Mbps (802

7、.11b) "54Mbps (802. 11a),或包含以上兩條頻帶的產(chǎn)品。理 論上只要用戶位于一 個接入點四周的一定區(qū)域內(nèi)，就能以最高約UMb/s的速度接入Web。但實際上， 如果有多個用戶同時通過一個點接入，帶寬被多個用戶分 享。由于 Wi-Fi 使用電波作為傳送媒介，資料包被截取的可能性高，這成為 用戶 所擔憂問題?，F(xiàn)在 Wi-Fi 產(chǎn)品利用 WED (Wired Equivalent Privacy) 技 術作資料加密 之用。然而，其 XX 的效能卻倍受質(zhì)疑，支援新一代加密方式的 Wi-Fi 產(chǎn)品亦相 繼出現(xiàn)。雖然 Wi-Fi 在數(shù)據(jù)平安性方面比藍牙技術要差一些， 但在電波的

8、覆蓋 X 圍方面卻略勝一籌，可達 100 m 左右。Wi-Fi 可以提供熱點覆蓋、低移動性和高數(shù)據(jù)傳輸速率，無線接入和高速 傳 輸是 Wi-Fi 技術的主要特點。國內(nèi)的電信、網(wǎng)通、移動都非常關注 Wi-Fi 技 術的 開展和應用。基于熱點的接入效勞曾經(jīng)一度被看成是對 3G的巨大沖擊，但 Wi-Fi 技術傳輸距離短和信號穿透能力差的特點同樣也是不可克服的。2. 2 Wi-Fi 技術的優(yōu)勢近兒年， WAP 的數(shù)量呈迅猛增長， 無線網(wǎng)絡的方便與高效使其得到迅速的普 及。無論是無線城市的建設， 還是企事業(yè)單位局域網(wǎng)的開通， 還是 的 Wi-Fi 功 能，都與 Wi-Fi 技術自身的優(yōu)勢是分不開的：1)

9、 較廣的局域網(wǎng)覆蓋 X 圍基于藍牙技術的電波覆蓋 X圍非常小，半徑大約只有15m,而Wi-Fi的半 徑 那么可達 100 m ,可以覆蓋整棟辦公大樓；2) 傳輸速度快Wi-Fi技術傳輸速度非?？?，可以到達 11Mbps (802. lib)或者54Mbps(802. 11a),適合高速數(shù)據(jù)傳輸?shù)臉I(yè)務；3) 無需布線Wi-Fi 最主要的優(yōu)勢在于不需要布線， 可以不受布線條件的限制， 因此非常 適 合移動辦公用戶的需要。在機場、車站、咖啡店、圖書館等人員較密集地方設 置 “熱點， 并通過高速線路將因特網(wǎng)接入上述場所。 用戶只要將支持無線 LAN 的 筆記本電腦或 PDA 拿到該區(qū)域內(nèi)，即可高速接入

10、因特網(wǎng)；4) 健康平安IEEE802. 11規(guī)定的發(fā)射功率不可超過 100毫瓦，實際發(fā)射功率約 60? 70 毫瓦， 而 的發(fā)射功率約 200毫瓦? 1瓦間，手持式對講機高達 5瓦。與后者 相比, Wi-Fi 產(chǎn)品的輻射更小。3 結論每一種無線通信方式都有其獨特之處， 超寬帶技術傳輸速率高， Wi-Fi 技術 覆 蓋 X 圍廣。隨著無線通信技術的開展， 人們對高速短距離無線通信的要求越來 越 高，超寬帶技術、 Wi-Fi 技術都有著廣泛的開展前景。UWB technology and other short-range wireless munications technology is pa

11、redAs personal munication consumer electronics industry in the rapid development, short-range wireless munication field of all kinds of new skills ,art, new methods to emerge in endlessly, toward faster and more convenient and more safe and effective etc. The new technology in the development of the

12、 Intel access, information home appliances, mobile office, industrialization and other fields has been widely used. Among them, ultra-wideband (UWB) Wide Band, the mk-ultra technology is in after 1990*s developed a kind of with high potential new wireless munication technology, it was listed as one

13、of the ten future munication technology.1 uwb wireless municationLI ultra -wideband technology introductionUWB (the mk-ultra Wideband, ultra -wideband) technology is currently has been widely studied a new wireless munication technology, it has bee a high-speed wireless personal nets (WPAN first cho

14、ice of the technology. UWB refers to the signal bandwidth than 500MHz or is the signal bandwidth and center frequency ratio is more than 25% of munications technologies? With the mon use of continuous carrier munication mode is different, use of UWB wireless signals center frequency 4.1 GHz bandwidt

15、h of 1.4 GHz, spectral range is very wide, but transmission power is very low. munications speed in 250Kbit between lOMbit/SEC ? In 250Kbit/SEC transmission speeds can ensure as munication distance. In short (13m below) a has great advantage, highest transmission speed can reach lGb/S? While the tra

16、ditional narrowband technology in long distance, low speed transmission dominant.Ultra-wideband (UWB) technology is initially applied to develop the radar oriented, it is generally thought that it belongs to a kind of carrierless munications technologies. February 2002, the United States the FCC for

17、mally its suspension. Currently ultra-wideband (UWB) technology is being integrated into the family cinema and portable products, mainly used for video and audio signal of wireless transmission. Ultra ? wideband (UWB) since when published has been regarded as bluetooth technology substitute, and oth

18、er wireless technologies such as WLAN, bluetooth etc pared ultra-wideband (UWB), with low power waste, high bandwidth and low plexity, the advantages of low cost, can pletely satisfy short family entertainment application requirements. 1.2 ultra-wideband performance characteristics ?Uwb wireless mun

19、ication is a very different to the traditional technology of wireless munication technology. It can realize the wireless LAN LAN and personal regional network PAN wireless Internet and access interface. UWB has the following features:1) strong anti-jamming performanceUWB signal, the launch will be w

20、eak radio pulse signal scattered on the broad band, output power and even lower than ordinary equipment of the noise? Received will signal energy reduction out, in the solution enlarge produced during spread spectrum gain. Therefore, and IEEE 802? 11 a, IEEE 802? 11 b and bluetooth.pared to the same

21、 code speed conditions, the UWB has a strong anti-jamming?2) transmission rate Is highUWB with very wide frequency bandwidth for high-speed data transmission, and not alone occupy now already crowded frequency resource, but sharing other wireless technology using frequency band? The data rate can re

22、ach dozens megabit per second to hundreds of megabit per second, is expected to 100 times higher than bluetooth, also can prep above IEEE 8021 a and IEEE 802.11 b.3) with very wide bandwidthUWB use of bandwidth in 1GHz above, up to a few ji hz and can and current narrowband munication system working

23、 at the same time and not interfere with each other. This in frequency resource of increasingly scarce today opened up a new time-domain radio resources?4) spectrum is high efficiency, the system of large capacityBecause it does not need to produce sine carrier signal that can be directly launch imp

24、ulse sequence, thus ultra wideband (UWB) technology has a wide spectrum and very low average power, which is beneficial to coexist with other systems, so as to improve the frequency spectrum utilization rate, which brings a lot of system capacit y.5) low powerUltra wideband (UWB) technology use inte

25、rmittent pulses to send data, pulse lasted for a very short time, is in monly 0.20 ns ? 1.5 ns between, have very low accounted for empty factor, the system power consumption can be done veiy low, in high speed munications system when consume only for hundreds of muon W ? dozens mW. At the same time

26、 because ultra wideband (UWB) technology of spread spectrum signal processing is relatively large, even if the gain USES low gain omni-directional antenna with emission, also can use less than lmW launch power realization thousands of meters of municat ion ?6) good safetyUWB safety performance in tw

27、o aspects: one is to adopt the jump spread spectrum, receiver only known the sender spread spectrum yaids to work out emission data; On the other hand is the transmission power spectral density is extremely low. Useful information pletely submerged in noise, be intercept probability is small, be det

28、ection probability is low, with traditional receiver cannot receive?2 Wi ? Fi2.1 Wi - Fi technology introductionWi - Wireless Fidelity, Wireless Fi (high-fidelity) is a kind of Wireless niunication protocol, official name is IEEE802.11 b.Wi ? Fi is Ethernet a wireless expand. Wi - Fi network can use

29、 to interconnect puter links on the Internet. Wi - Fi network in no license 2.4 and 5 gigabit bandwidth management, Hz radio data rate can reach 11Mbps (802.11 b)? 54Mbps (802.11 a), or include the above two bands of products? If the user is located in an access point theoretically around certain re

30、gion, can with highest about 11 Mb/s faster access Web? But in fact, if there are multiple users at the same time through a point access, bandwidth by multiple users to share.Because Wi - Fi use waves as transmission medium, material package to be intercepted tall, this be the possibility of users a

31、re worried about problems. Now Wi - Fi product use Wired Equivalent without (WED) technology data encryption purposes. However, its performance is highly confidential scepticism, support the new generation encryption method Wi - Fi products also arise. Although Wi - Fi in data security than bluetoot

32、h technology will send some, but in waves coverage was slightly better, can amount to 100 m or so.Wi - Fi may provide hot coverage, low mobility and high speed of data transmission, wireless access and transmission with high speed is Wi - Fi technical main characteristics.Domestic telemunication, C,

33、 mobile are very concerned Wi ? Fi technology development and application. Based on the hotspot access service once considered the huge impact on 3G, but Wi ? Fi technology transmission distance is short and signals penetrate the characteristics of poor ability also insurmountable.2.2 Wi - Fi techni

34、cal superiorityIn recent years, the number of WAP at a rapid pace, wireless network convenience and efficient make its rapid popularization. Whether wireless urban construction, or business unit of LAN opening, or mobile phones Wi ? Fi function, all with Wi - Fi technical advantages of itself is not divided:1) wider LAN coverageBased on bluetooth radio coverage is very small, radius, and only about 15m Wi - Fi radius criterion of up to 100 m. can cover whole building office building,2) transmission speedWi ? Fi technology transmission is very fast, can achieve 11Mbps (802.11 b) or 54Mbps (80