中英對照 超寬帶技術(shù)與其它短距離無線通信技術(shù)的比較

1、超寬帶技術(shù)與其它短距離無線通信技術(shù)的比較隨著個人通信消費電子產(chǎn)業(yè)的迅猛發(fā)展，短距離無線通信領(lǐng)域的各種新技術(shù)、新方法層出不窮，朝著更快、更方便、更安全有效等方面進(jìn)行發(fā)展。新的技術(shù)在 Intel 接入、信息家電、移動辦公、工業(yè)化等各個領(lǐng)域得到了廣泛的運用。其中，超寬帶（Ultra Wide Band，UWB）技術(shù)是在 20世紀(jì)90 年代以后發(fā)展起來的一種具有巨大發(fā)展?jié)摿Φ男滦蜔o線通信技術(shù)，被列為未來通信的十大技術(shù)之一 。1 超寬帶無線通信 1.1 超寬帶技術(shù)簡介 UWB（Ultra Wideband，超寬帶）技術(shù)是目前正被廣泛研究的一種新興無線通信技術(shù)，現(xiàn)在已經(jīng)成為高速無線個人網(wǎng) （WPAN）的首

2、選技術(shù)。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(shù)。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，頻譜范圍很寬，但是發(fā)射功率非常低。通信速度在250Kbit10Mbit/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(dá) 1Gb/S。而傳統(tǒng)的窄帶技術(shù)在長距離、低速傳輸具有優(yōu)勢。 超寬帶（UWB）技術(shù)最初是面向雷達(dá)應(yīng)用來開發(fā)的，一般認(rèn)為它屬于一種無載波通信技術(shù)。2002 年 2 月，美國聯(lián)邦通信委員會（FCC）正式將其解禁

3、。目前超寬帶（UWB）技術(shù)正被整合進(jìn)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(lán)牙技術(shù)的替代品，與其他無線技術(shù)如 WLAN 、藍(lán)牙等相比，超寬帶（UWB）具有低功耗、高帶寬、低復(fù)雜度、低成本的優(yōu)點，完全可以滿足短距離家庭娛樂應(yīng)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(shù)有很大不同的無線通信技術(shù)。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具有以下特點： 1）抗干擾性能強(qiáng) 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(shè)備產(chǎn)生的噪聲。接收時將信號能量還原出來，

4、在解擴(kuò)過程中產(chǎn)生擴(kuò)頻增益。因此，與 IEEE 802.11a、IEEE 802.11b 和藍(lán)牙相比，在同等碼速條件下，UWB具有更強(qiáng)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(shù)使用的頻帶。其數(shù)據(jù)速率可以達(dá)到幾十兆比特每秒到幾百兆比特每秒，有望高于藍(lán)牙100倍，也可以高于IEEE 802.11a和 IEEE 802.11b。 3）帶寬極寬 UWB 使用的帶寬在 1GHz 以上，高達(dá)幾吉赫茲，并且可以和目前的窄帶通信系統(tǒng)同時工作而互不干擾。這在頻率資源日益緊張的今天開辟了一種新的時域無線電資源。 4）頻

5、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 UWB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0.20ns1.5ns 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)的耗電量僅為幾百 W幾十 mw。同時由于 UWB系統(tǒng)信號的擴(kuò)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 1mW 的發(fā)射功率實現(xiàn)幾千米的通信。 6）安全性好 UWB 安全性表現(xiàn)在兩方面：一方面是采用跳時擴(kuò)頻，接收機(jī)只有已知發(fā)送端擴(kuò)頻碼時才

6、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(jī)無法接收。 2 Wi-Fi 2.1 Wi-Fi技術(shù)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IEEE802.11b。 Wi-Fi 是以太網(wǎng)的一種無線擴(kuò)展，Wi-Fi 網(wǎng)絡(luò)可以使用來互連電腦鏈接上互連網(wǎng)。Wi-Fi 網(wǎng)絡(luò)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(dá) 11Mbps（802.11b）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

7、區(qū)域內(nèi)，就能以最高約 11Mb/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(dān)心問題。現(xiàn)在 Wi-Fi 產(chǎn)品利用WED（Wired Equivalent Privacy）技術(shù)作資料加密之用。然而，其保密的效能卻倍受質(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)安全性方面比藍(lán)牙技術(shù)要差一些，但在電波的覆蓋范圍方面卻略勝一籌，可達(dá) 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

8、術(shù)的主要特點。國內(nèi)的電信、網(wǎng)通、移動都非常關(guān)注 Wi-Fi 技術(shù)的發(fā)展和應(yīng)用。基于熱點的接入服務(wù)曾經(jīng)一度被看成是對3G的巨大沖擊， 但Wi-Fi技術(shù)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(shù)的優(yōu)勢 近幾年，WAP 的數(shù)量呈迅猛增長，無線網(wǎng)絡(luò)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(shè)，還是企事業(yè)單位局域網(wǎng)的開通，還是手機(jī)的 Wi-Fi 功能，都與Wi-Fi 技術(shù)自身的優(yōu)勢是分不開的： 1）較廣的局域網(wǎng)覆蓋范圍 基于藍(lán)牙技術(shù)的電波覆蓋范圍非常小，半徑大約只有 15m，而 Wi-Fi 的半徑則可達(dá)100 m，可以覆蓋整棟辦公大樓； 2）傳輸速度快 Wi-F

9、i 技術(shù)傳輸速度非常快，可以達(dá)到 11Mbps（802.11b）或者 54Mbps （802.11a），適合高速數(shù)據(jù)傳輸?shù)臉I(yè)務(wù)； 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(jī)場、車站、咖啡店、圖書館等人員較密集地方設(shè)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)，即可高速接入因特網(wǎng)； 4）健康安全 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 6070毫瓦，而手機(jī)的發(fā)射功率約 200毫瓦1瓦間，手持式對講機(jī)高達(dá)5瓦。與后者相比，Wi-F

10、i 產(chǎn)品的輻射更小。 3 結(jié)論 每一種無線通信方式都有其獨特之處，超寬帶技術(shù)傳輸速率高，Wi-Fi 技術(shù)覆蓋范圍廣。隨著無線通信技術(shù)的發(fā)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(shù)、Wi-Fi 技術(shù)都有著廣泛的發(fā)展前景。UWB technology and other short-range wireless communications technology is comparedAs personal communication consumer electronics industry in the rapid development, short-range wireless

11、 communication 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 Intel access, information home appliances, mobile office, industrialization and other fields has b

12、een widely used. Among them, ultra-wideband (UWB) Wide Band, the mk-ultra technology is in after 1990s developed a kind of with high potential new wireless communication technology, it was listed as one of the ten future communication technology.1 uwb wireless communication 1.1 ultra-wideband techno

13、logy introduction UWB (the mk-ultra Wideband, ultra-wideband) technology is currently has been widely studied a new wireless communication technology, it has become a high-speed wireless personal nets (WPAN first choice of the technology. UWB refers to the signal bandwidth than 500MHz or is the sign

14、al bandwidth and center frequency ratio is more than 25% of communications technologies. With the common use of continuous carrier communication mode is different, use of UWB wireless signals center frequency 4.1 GHz, bandwidth of 1.4 GHz, spectral range is very wide, but transmission power is very

15、low. Communications speed in 250Kbit between 10Mbit/SEC. In 250Kbit/SEC transmission speeds can ensure as communication distance. In short (13m below) a has great advantage, highest transmission speed can reach 1Gb/S. While the traditional narrowband technology in long distance, low speed transmissi

16、on 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 communications technologies. February 2002, the United States the FCC formally its suspension. Currently ultra-wideband (UWB) technology is

17、 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 other wireless technologies such as WLAN, bluetooth etc compared ultra-

18、wideband (UWB), with low power waste, high bandwidth and low complexity, the advantages of low cost, can completely satisfy short family entertainment application requirements. 1.2 ultra-wideband performance characteristics.Uwb wireless communication is a very different to the traditional technology

19、 of wireless communication 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 performance UWB signal, the launch will be weak radio pulse signal scattered on the broad band, o

20、utput 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,compared to the same code speed conditions, the UWB has a strong anti-ja

21、mming.2) transmission rate is high UWB 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 reach dozens megabit per second to hundreds of megabi

22、t per second, is expected to 100 times higher than bluetooth, also can prep above IEEE 802.11a and IEEE 802.11b . 3) with very wide bandwidth UWB use of bandwidth in 1GHz above, up to a few ji hz and can and current narrowband communication system working at the same time and not interfere with each

23、 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 capacity Because it does not need to produce sine carrier signal that can be directly launch impulse sequence, thus ultra wideband (UWB) te

24、chnology 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 capacity. 5) low power Ultra wideband (UWB) technology use intermittent pulses to send data, pulse lasted

25、 for a very short time, is in commonly 0.20 ns 1.5 ns between, have very low accounted for empty factor, the system power consumption can be done very low, in high speed communications system when consume only for hundreds of muon W dozens mW. At the same time because ultra wideband (UWB) technology

26、 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 1mW launch power realization thousands of meters of communication. 6) good safety UWB safety performance in two aspects: one is to adopt the jump s

27、pread spectrum, receiver only known the sender spread spectrum yards to work out emission data; On the other hand is the transmission power spectral density is extremely low. Useful information completely submerged in noise, be intercept probability is small, be detection probability is low, with tr

28、aditional receiver cannot receive.2 Wi - Fi 2.1 Wi - Fi technology introduction Wi - Wireless Fidelity, Wireless Fi (high-fidelity) is a kind of Wireless communication protocol, official name is IEEE802.11 b. Wi - Fi is Ethernet a wireless expand, Wi - Fi network can use to interconnect computer lin

29、ks 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 region, can with highest abou

30、t 11Mb/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 are worried about problems.

31、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 bluetooth technology will send some

32、, 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 telecommunication, CNC, mobile are very con

33、cerned 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 technical superiority In

34、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 coverage Based 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 speed Wi - Fi technology transmission is very fast, can achieve 11Mbps (802.11 b) or 54Mbps (802