超宽带技术与其它短距离无线通信技术的比较解析

1、超宽带技术与其它短距离无线通信技术的比较随着个人通信消费电子产业的迅猛发展，短距离无线通信领域的各种新技术、 新方法层出不穷，朝着更快、更方便、更安全有效等方面进行发展。新的技 术在 In tel接入、信息家电、移动办公、工业化等各个领域得到了广泛的运用。其中， 超宽带（Ultra Wide Ba nd, UWB技术是在20世纪90年代以后发展起 来的一种具有 巨大发展潜力的新型无线通信技术，被列为未来通信的十大技术之一。1超宽带无线通信1.1超宽带技术简介UWB （Ultra Wideba nd,超宽带技术是目前正被广泛研究的一种新兴无线通信技术，现在已经成为高速无线个人网（WPAN的首选技

2、术。UWB是指信号带宽大于500MHz或者是信号带宽与中心频率之比大于 25%的 通信技术。与常见的通信方式使用连续的载波不同，UWB中使用的无线信号中心 频率为4.1GHz,带宽为1.4GHz，频谱范围很宽，但是发射功率非常低。通信速 度在 250Kbit 10Mbit/秒之间。在250Kbit/秒的传输速度下可确保 30m的通信距离。在 短距离（13m以下有很大优势,最高传输速度可达1Gb/S。而传统 的窄带技术在长距 离、低速传输具有优势。超宽带（UWB技术最初是面向雷达应用来开发的，一般认为它属于一种无 载波 通信技术。2002年2月,美国联邦通信委员会（FCC正式将其解禁。目前超宽带

3、 （UWB技术正被整合进家庭影院和便携式产品，主要用于视频和音 频信号的无线发 送。宽带（UWB自问世后一直被看作是蓝牙技术的替代品，与其他无线技术如 WLAN、蓝牙等相比，超宽带（UWB具有低功耗、高带宽、低复杂度、低成本的优点,完全可以满足短距离家庭娱乐应用需求。1.2超宽带性能特点。超宽带无线通信是一种与传统技术有很大不同的无线通信技术。它能够实现无线局域网LAN和个人区域网PAN中无线接口的互联和接入。UWB具有以下特占.八、1抗干扰性能强UWB信号,在发射时将微弱的无线电脉冲信号分散在宽阔的频带中，输出功率甚至低于普通设备产生的噪声。接收时将信号能量还原出来，在解扩过程中产 生扩频增

4、益。因此，与IEEE 802.11a、IEEE 802.11b和蓝牙相比，在同等码速 条件下, UWB具有更强的抗干扰性。2传输速率高UWB以非常宽的频率带宽来换取高速的数据传输,并且不单独占用现在已经 拥挤不堪的频率资源，而是共享其他无线技术使用的频带。其数据速率可以达到 几十兆比特每秒到几百兆比特每秒，有望高于蓝牙100倍，也可以高于IEEE 802.11a和 IEEE 802.11b。3带宽极宽UWB使用的带宽在1GHz以上，咼达几吉赫兹，并且可以和目前的窄带通信 系 统同时工作而互不干扰。 这在频率资源日益紧张的今天开辟了一种新的时域无 线 电资源。4频谱利用率高，系统容量大因为不需要

5、产生正弦载波信号，可以直接发射冲激序列，因而UWB系统具有很 宽的频谱和很低的平均功率，有利于与其他系统共存，从而提高频谱利用率，带来了 极大的系统容量。5功率低UWB系统使用间歇的脉冲来发送数据，脉冲持续时间很短，一般在0.20ns 1.5ns之间，有很低的占空因数，系统耗电可以做到很低，在高速通信时系统的 耗电 量仅为几百卩W几十mw。同时由于UWB系统信号的扩频处理增益比较 大，即使 采用低增益的全向天线发射，也可使用小于1mW的发射功率实现几千 米的通信。6安全性好UWB安全性表现在两方面：一方面是采用跳时扩频,接收机只有已知发送端扩 频码时才能解出发射数据；另一方面是系统的发射功率谱

6、密度极低。有用信息完全淹没在噪声中，被截获概率很小，被检测的概率也很低，用传统的接收机无 法接 收。2 Wi-Fi2.1 Wi-Fi技术简介Wi-Fi (Wireless Fidelity,无线高保真也是一种无线通信协议，正式名 称是 IEEE802.11b。Wi-Fi是以太网的一种无线扩展,Wi-Fi网络可以使用来互连电脑链接上互连 网。Wi-Fi网络在无执照的2.4和5千兆Hz的无线电频带经营，数据速 率可达 11Mbps(802.11b 54Mbps(802.11a或包含以上两条频带的产品。理论上只要用户位于一个接入点四周的一定区域内,就能以最高约11Mb/s的速度接入Web。但实 际上

7、，如果有多个用户同时通过一个点接入，带宽被多个用户 分享。由于Wi-Fi使用电波作为传送媒介，资料包被截取的可能性高，这成为用户所 担心问题。现在 Wi-Fi产品利用 WED (Wired Equivale nt Privacy技术作资料加密之 用。然而，其保密的效能却倍受质疑,支援新一代加密方式的Wi-Fi产品亦相继出 现。虽然Wi-Fi在数据安全性方面比蓝牙技术要差一些，但在电波的覆盖范围方面 却略胜一筹，可达100 m左右。Wi-Fi可以提供热点覆盖、低移动性和高数据传输速率，无线接入和高速传输 是Wi-Fi技术的主要特点。国内的电信、网通、移动都非常关注Wi-Fi技术的发展和应用。基于

8、热点的接入服务曾经一度被看成是对3G的巨大冲击,但Wi-Fi技术传输距离短和信号穿透能力差的特点同样也是不可克服的。2.2 Wi-Fi技术的优势近几年,WAP的数量呈迅猛增长,无线网络的方便与高效使其得到迅速的普及。无论是无线城市的建设，还是企事业单位局域网的开通，还是手机的Wi-Fi功 能，都与Wi-Fi技术自身的优势是分不开的：1较广的局域网覆盖范围基于蓝牙技术的电波覆盖范围非常小,半径大约只有15m,而Wi-Fi的半径则 可达100 m,可以覆盖整栋办公大楼；2传输速度快Wi-Fi技术传输速度非常快，可以达到11Mbps(802.11b或者54Mbps(802.11a适合高速数据传输的业

9、务；3无需布线Wi-Fi最主要的优势在于不需要布线，可以不受布线条件的限制，因此非常适合 移动办公用户的需要。在机场、车站、咖啡店、图书馆等人员较密集地方设置热点”并通过高速线路将因特网接入上述场所。 用户只要将支持无线LAN的笔记本 电脑或PDA拿到该区域内，即可高速接入因特网；4健康安全IEEE802.11规定的发射功率不可超过100毫瓦，实际发射功率约6070毫瓦，而 手机的发射功率约200毫瓦1瓦间,手持式对讲机高达5瓦。与后者相比,Wi-Fi 产品的辐射更小。3结论每一种无线通信方式都有其独特之处，超宽带技术传输速率高，Wi-Fi技术覆盖 范围广。随着无线通信技术的发展，人们对高速短

10、距离无线通信的要求越来越高， 超宽带技术、Wi-Fi技术都有着广泛的发展前景。UWB tech no logy and other short-ra nge wireless com muni cati ons tech no logy is comparedAs pers onal com muni cati on con sumer electr onics in dustry in the rapid developme nt, short-ra nge wireless com muni cati on field of all kinds of new skills ,art, ne

11、w methods to emerge in en dlessly, toward faster and more convenient and more safe and effective etc. The new tech no logy in the developme nt of the In tel access, in formati on home applia nces, mobile office, industrialization and other fields has been widely used. Among them, ultra-wideba nd (UW

12、B Wide Band, the mk-ultra tech nology is in after 1990s developed a kind of with high pote ntial new wireless com muni cati on tech no logy, it was listed as one of the ten future com muni cati on tech no logy.1 uwb wireless com muni cati on1.1 ultra-wideba nd tech no logy in troducti onUWB (the mk-

13、ultra Wideba nd, ultra-wideba nd tech no logy is curre ntly has bee n widely studied a new wireless com muni cati on tech no logy, it has become a high-speed wireless pers onal n ets (WPAN first choice of the tech no logy. UWB refers to the sig nal ban dwidth tha n 500MHz or is the sig nal ban dwidt

14、h and cen ter freque ncy ratio is more tha n 25% of com muni cati ons tech no logies. With the com mon use of continu ous carrier com muni cati on mode is differe nt, use of UWB wireless sig nals cen ter freque ncy 4.1 GH z, ban dwidth of 1.4 GHz, spectral range is very wide, but tran smissi on powe

15、r is very low. Commu ni catio ns speed in 250Kbit betwee n 10Mbit/SEC. In 250Kbit/SEC tran smissio n speeds can en sure as com muni cati on dista nee. In short (13m below a has great adva ntage, highest tran smissi on speed can reach 1Gb/S. While the traditi onal n arrowba nd tech no logy in long di

16、sta nee, low speed tran smissi on dominant.Ultra-wideba nd (UWB tech no logy is in itially applied to develop the radar orie nted,it is gen erally thought that it bel ongs to a ki nd of carrierless com muni cati onstech no logies. February 2002, the Un ited States the FCC formally its suspe nsion.Cu

17、rre ntly ultra-wideba nd (UWB tech no logy is being in tegrated into the family cin ema and portable products, mainly used for video and audio sig nal of wireless tran smissi on. Ultra-wideba nd (UWB since whe n published has bee n regarded as bluetooth tech no logy substitute, and other wireless te

18、ch no logies such as WLAN, bluetooth etc compared ultra- wideba nd (UWB, with low power waste, high ban dwidth and low complexity, the adva ntages of low cost, can completely satisfy short family en terta inment applicati on requireme nts. 1.2 ultra-wideba nd performa nee characteristics.Uwb wireles

19、s com muni cati on is a very differe nt to the traditi onal tech no logy of wireless com muni cati on tech no logy. It can realize the wireless LAN LAN and pers onal regi onal n etwork PAN wireless Internet and access in terface. UWB has the followi ng features:1 strong an ti-jam ming performa nee U

20、WB sig nal, the launch will be weak radio pulse sig nal scattered on the broad band, output power and eve n lower tha n ordi nary equipme nt of the no ise. Received will sig nal en ergy reduct ion out, i n the soluti on enl arge produced duri ng spread spectrum gain. Therefore, and IEEE 802.11 a, IE

21、EE 802.11 b and bluetooth,compared to the same code speed con diti ons, the UWB has a strong an ti- jamming. 2 tran smissi on rate is high UWB with very wide freque ncy ban dwidth for highspeed data tran smissi on, and not alone occupy now already crowded freque ncy resource, but shari ng other wire

22、less tech no logy using freque ncy band. The data rate can reach doze ns megabit per sec ond to hun dreds of megabit per sec on d, is expected to 100 times higher than bluetooth, also can prep above IEEE 802.11a and IEEE 802.11b . 3 with very wide ban dwidth UWB use of ban dwidth in 1GHz above, up t

23、o a few ji hz and can and curre nt n arrowba nd com muni cati on system worki ng at the same time and not in terfere with each other. This in frequency resource of increasingly scarce today opened up a new time-doma in radio resources. 4 spectrum is high efficie ncy, the system of large capacity Bec

24、ause it does not n eed to produce sine carrier sig nal that can be directly launch impulse seque nee, thus ultra wideba nd (UWB tech no logy has a wide spectrum and very low average power, which is beneficial to coexist with other systems, so as to improve the freque ncy spectrum utilizatio n rate,

25、which brings a lot of system capacity. 5 low power Ultra wideba nd (UWB tech no logy use in termitte nt pulses to send data, pulse lasted for a very short time, is in com monly 0.20 ns 1.5 ns betwee n, have very low acco un ted for empty factor, the system power con sumpti on can be done very low, i

26、 nhigh speed com muni cati ons system whe n con sume on ly for hun dreds of muon W doze ns mW. At the same time because ultra wideba nd (UWB tech no logy of spread spectrum signal processing is relatively large, even if the gain USES low gain omnidirecti onal antenna with emission, also can use less

27、 than 1mW launch power realization thousa nds of meters of com muni catio n. 6 good safety UWB safety performa nee in two aspects: one is to adopt the jump spread spectrum, receiver only known the sen der spread spectrum yards to work out emissi on data; On the other hand is the tran smissi on power

28、 spectral density is extremely low. Useful information completely submerged in noise, be in tercept probability is small, be detect ion probability is low, with traditi onal receiver cannot receive. 2 Wi - Fi 2.1 Wi - Fi tech no logy in troduct ion Wi - Wireless Fidelity, Wireless Fi (high-fidelity

29、is a ki nd of Wireless com muni cati on protocol, official n ame is IEEE802.11 b. Wi - Fi is Ethernet a wireless expa nd, Wi - Fi network can use to in terc onnect computer links on the In ternet. Wi - Fi n etwork in no lice nse 2.4 and 5 gigabit ban dwidth man ageme nt, Hz radio data rate can reach

30、 11Mbps (802.11 b 54Mbps (802.11 a, or in clude the above two bands of products. If the user is located in an access point theoretically around certain region, can with highest about 11Mb/s faster access Web. But in fact, if there are multiple users at the same time through a point access, ban dwidt

31、h by multiple users to share. Because Wi - Fi use waves as tran smissi on medium, material package to be in tercepted tall, this be the possibility of users are worried about problems. Now Wi Fi product use Wired Equivale nt without (WED tech no logy data en crypti on purposes. However, its performa

32、 nee is highly con fide ntial scepticism, support the new generation encryption method Wi - Fi products also arise. Although Wi - Fi in datasecurity tha n bluetooth tech no logy will send some, but in waves coverage was slightly better, can amount to 100 m or so. Wi - Fi may provide hot coverage, lo

33、w mobility and high speed of data tran smissi on, wireless access and tran smissi on with high speed is Wi - Fi tech ni cal main characteristics. Domestic telecom muni cati on, CNC, mobile are very concerned Wi - Fi tech no logy developme nt and applicatio n. Based on the hotspot access service once

34、 con sidered the huge impact on 3G, but Wi - Fi tech no logy transmission distance is short and signals penetrate the characteristics of poor ability also in surm oun table. 2.2 Wi - Fi tech ni cal superiority In rece nt years, the nu mber of WAP at a rapid pace, wireless n etwork convenience and ef

35、ficie nt make its rapid popularizati on. Whether wireless urba n con structi on, or bus in ess unit of LAN ope ning, 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 criterio n of up to 100 m, can cover whole build ing office buildi ng, 2 tran smissi on speed Wi - Fi tech no logy tran smissi on is very fast, can achieve 11Mbps (802.11 b or 54Mbps (802.11 a, suitable fo