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1、,Wireless Communication Fundamentals,Dr.Jiang Zhu,Professor,Department of Military Communication Engineering,School of Electronic Science and Engineering,Wired Vs.Wireless Communication,Wired Vs.Wireless Communication,Wired Vs.Wireless Communication,How does signal propagate?How much attenuation tak
2、e place?How does signal look like at the receiver?How does signals using the same propag-ation channel?,Wired Vs.Wireless Communication,Provide comprehensive understanding of fundamental principles underlying wireless communications and networkingPrinciples include:Characteristics and performance li
3、mits of wireless systems Techniques to overcome the difficulties,Goal of This Course,Outline,Outline,Email:jiangzhugfkd.mtn Phone:74477 13787179473Office:103 room,4th Departments General Building,Course information,Instructor Information,Course information,Text Wireless Communications and Networking
4、 by Jon W.Mark and Weihua Zhuang Reference Modern Wireless Communications by Simon Haykin and Michael Moher Lecture Notes by Dr.Jiang Zhu,Course Material,Course information,Some basic knowledge of communication Some basic knowledge of signals and systems Some basic knowledge of probability and stati
5、stics,Prerequisites,Course information,Class Time:18 Lectures(36 credit hours)Labs:4 credit hours Final exam:?,Time&schedule,Course information,Experiment 15%Homeworks&Class Participation 5%Final Exam 80%,Grading,Outline,Introduction to main topics,Introduction to main topics,Introduction to main to
6、pics,Introduction to main topics,Introduction to main topics,Outline,1.1 Definition of Wireless communication,Transmitting voice and data using electromagnetic waves in open space Electromagnetic waves Travel at speed of light(c=3x108 m/s)Has a frequency(f)and wavelength(l)c=f l,What is wireless com
7、munication?,1.1 Definition of Wireless communication,Propagation characteristics are different in each frequency band,AM radio,S/W radio,FM radio,TV,TV,cellular,What is wireless communication?,1.1 Definition of Wireless communication,Ground Wave,Sky wave,Space wave,What is wireless communication?,1.
8、1 Definition of Wireless communication,Provides mobilityA user can send or receive a message no matter where he or she is located Added convenience/reduced costEnables communication without installing an expensive infrastructure,1.1 Definition of Wireless communication,Why use wireless comm?,1.1 Def
9、inition of Wireless communication,The wireless channel Wireless channels are a difficult and capacity limited broadcast communications medium Modulation、coding、equalization、diversity etc.User mobility Traffic patterns,user locations,and network conditions are constantly changing Handoff and Location
10、 management,Challenges of wireless comm,1.1 Definition of Wireless communication,The fundamental physical resource in wireless systems is the radio spectrum.The development of wireless communications has often a search for more efficient ways of using the radio spectrum.,Challenges of wireless comm,
11、1.1 Definition of Wireless communication,OSI Model,This layer provides the physical mechanism for transmitting bits between any pair of nodes.,One purpose of the data-link layer is to perform error correction of detection,this layer is also responsible for the way in which different users share the
12、transmission medium.,This layer has several functions,one of which is to determine the routing of the information.A second function is flow control,to ensure that the network does not become congested.,1.2 History of wireless communication,1864-Maxwell predicts existence of electro-magnetic(EM)waves
13、 1887-Hertz proves existence of EM waves;first spark transmitter generates a spark in a receiver several meters away 1890-Branly develops coherer for detecting radio waves 1896-Marconi demonstrates wireless telegraph to English telegraph office,Before the“Birth of Radio”,1864-1896,1.2 History of wir
14、eless communication,莫尔斯电报和贝尔电话都是有线通信，当时人们认为电只能沿导线传输。可当时的英国科学家麦克斯韦尔不这样认为，早在1864年麦克斯韦尔就从理论上预言了电磁波的存在，他认为电能可以在空间以电磁波的形式存在，1864年麦克斯韦尔在英国皇家学院发表了他的第三篇著名论文电磁场力学的理论，在这篇论文中，麦克斯韦尔严格推导出完善的电磁波方程（麦克斯韦尔方程）并得出电磁波的传播速度等于光速（30万公里/秒）的重要结论。1887年德国物理学家赫兹用实验证实了电磁波的存在证明了麦克斯韦尔预见的正确性。,1895年，意大利的马可尼和俄国的波波夫把电磁波应用到无线电报通信中，但当时
15、电波的传送距离较近（20300公里），而且声音很微弱，只能用耳机收听，距离远了就听不见。直到1906年，26岁的美国青年，业余无线电爱好者德福雷斯特发明了具有放大能力的真空三极管后，通信技术有了突飞猛进的发展，先后出现了无线电广播，电视，无线电话，并发展到今天的计算机通信、卫星通信，光纤通信，网络通信，移动通信等。,1.2 History of wireless communication,“The Birth of Radio”,1897-Marconi awarded patent for wireless telegraph1897-First“Marconi station”estab
16、lished on Needles island to communicate with English coast 1898-Marconi awarded English patent for tuned communication 1898-Wireless telegraphic connection between England and France established,1901-Marconi successfully transmits radio signal across Atlantic Ocean from Cornwall to Newfoundland1902-
17、First bidirectional communication across Atlantic 1909-Marconi awarded Nobel prize for physics,1.2 History of wireless communication,Transoceanic Communication,1914-First voice over radio transmission1924-Bell Laboratories claim the first mobile 2-way voice based radio telephone1920s-Mobile receiver
18、s installed in police cars in Detroit1930s-Mobile transmitters developed;radio equipment occupied most of police car trunk1935-Frequency modulation(FM)demonstrated by Armstrong,1.2 History of wireless communication,Voice over Radio,1946-First interconnection of mobile users to public switched teleph
19、one network(PSTN)1947-(at Bell Labs)D.H.Ring described the cellular network idea in an internal memo.1969-The Bell System made commercial cellular radio operational by employing frequency reuse for the first time.1976-Bell Mobile Phone has 543 pay customers using 12 channels in the New York City are
20、a;waiting list is 3700 people;service is poor due to blocking,1.2 History of wireless communication,Birth of Mobile Telephony,1979-NTT/Japan deploys first cellular communi-cation system1983-Advanced Mobile Phone System(AMPS)deployed in US in 900 MHz band1989-Groupe Spcial Mobile defines European dig
21、ital cellular standard1991-US Digital Cellular phone system introduc-ed 1993-IS-95(CDMA)digital cellular system depl-oyed in US,1.2 History of wireless communication,Cellular Mobile Telephony,1995-FCC auctions off frequencies in Personal Communications System(PCS)band at 1.8 GHz for mobile telephony
22、,The auction money for six broadband PCS licensed bands(120 MHz)almost reaches 20 billion US dollars1999-ITU decides the next generation mobile com-munication systems(e.g.,W-CDMA,cdma2000,etc)2000s Third/fourth generation cellular system standards,Bluetooth,WiFi,ad hoc networks,sensor networks,1.2 H
23、istory of wireless communication,PCS and Beyond,1.2 History of wireless communication,History of Cellular Communication,1.2 History of wireless communication,Over 80%of worlds population has cellular coverage Over 3 billion cellular subscribers Half of the worlds population Many developed countries
24、have more subscribers than people,1.2 History of wireless communication,Cellular Phone Penetration,Cellular has enjoyed exponential growth since 1988 Ignited the recent wireless revolution Asia way ahead of the rest of the worldMuch hype in 1990s,great failures around 2000,1.2 History of wireless co
25、mmunication,Cellular Phone Penetration,1.3 Types of wireless communications,Mobile Cellular Networks Wireless Data Networks Mobile Satellite Communication Ad Hoc Networks Wireless Sensor Networks GPS Cordless Phone Paging System,Wireless Communication System,1.3 Types of wireless communications,Mobi
26、le Cellular Networks,1.3 Types of wireless communications,What is a cellular system?,FCC defines the cellular system as:A system in which assigned radio spectrum is divided into discrete channels,which are assigned in groups to geographic cells covering a cellular geographic service area.A system wh
27、ich uses radio transmission rather than physical wire lines to provide telephone service.,1.3 Types of wireless communications,Cellular System Characterized by,High mobility provisionWide-rangeTwo-way voice communicationHandoff and roaming supportIntegrated with sophisticated public switched telepho
28、ne network(PSTN)High transmit power requires at the handsets(2W),1.3 Types of wireless communications,Wireless Data Networks,1.3 Types of wireless communications,Wi-Fi short for Wireless Fidelity,is a set of standards for WLAN currently based on the IEEE 802.11specifications.WLAN using the IEEE 802.
29、11HiperLAN is a European Standard,Wireless LAN,1.3 Types of wireless communications,Wireless LAN,1.3 Types of wireless communications,Wireless LAN,1.3 Types of wireless communications,Wireless Personal Area Network(WPAN)IEEE 802.15.1 BluetoothIEEE 802.15.3 UWBIEEE 802.15.4 ZigBee Radios,Wireless PAN
30、,1.3 Types of wireless communications,Wireless PAN,Bluetooth,1.3 Types of wireless communications,Cover very large areasOptimized for one-way transmissionRadio(DAB)and movie(SatTV)broadcastingMost two-way systems struggling or bankruptExpensive alternative to terrestrial system,Mobile Satellite Comm
31、unication,1.3 Types of wireless communications,Peer-to-peer communications.No backbone infrastructure.Routing can be multihop.Topology is dynamic.,Ad Hoc Networks,1.3 Types of wireless communications,Ad Hoc Networks,1.3 Types of wireless communications,Wireless Sensor Networks,1.3 Types of wireless
32、communications,1.4 Development of wireless communication,1.4 Development of wireless communication,View wireless from different Angles,Telecom and Data Networking,Telecom Interest,Data Networking Interest,1.4 Development of wireless communication,1.4 Development of wireless communication,1.4 Develop
33、ment of wireless communication,Software Radio,JTRS,Course outline Overview of wireless communications Some history A positive view of the future of wireless communications,Conclusions,Why does FM signal offer better receptive quality compared with AM signal in wireless communication system?,Problems,
