3. Introduction
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Transcript of 3. Introduction
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Introduction to Wireless Communications
-----------------------------------------------------------------------------------------------------------------------------| TE 412 Introduction to Wireless Communications | Christine Mwase | 10/03/2014 | Slide 1/13 |
Communications
Introduction
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Introduction Outline
• What is Wireless Communications
• The Evolution of Wireless Communications
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• Broadband Wireless Technology
• Limitations and Difficulties of Wireless Technologies
• Wireless Communications in Tanzania
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
What is Wireless Communications?
• Communication System– A system over which information is transmitted from point A
to point B
• where the distance between them is beyond usual
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• where the distance between them is beyond usual voice or visual communication.
• Wireless Communications– Communicating information without wires
• using electromagnetic waves.
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Wireless Communications
• Freedom from wires– No wires to install (cost), no bundles of wires around
• Global coverage
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– Can reach where wiring cannot go (not feasible / cost), can stay connected (roaming allows flexibility anywhere and any time)
• Flexibility– Mobility, multiple connections
Any time, Any where, Any device
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Wireless vs. Mobile
• Wireless does not necessarily mean mobile• Fixed (e.g., IEEE 802.16 WirelessMAN)
• Portable (e.g., IEEE 802.11 WiFi, IEEE 802.15.3 UWB)
• Mobile (e.g., GSM, cdma2000)
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• Mobile (e.g., GSM, cdma2000)
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
The Evolution of Wireless Communications
• 1896: Guglielmo Marconi invented the wireless telegraph.– Communication by encoding alphanumeric characters in analogue signal– Sent telegraphic signals across the Atlantic Ocean
• 1940’s (late): Terrestrial fixed wireless links routinely providing phone service.
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phone service.
• 1960’s: Satellite links used for geostationary intercontinental communications.
• 1980’s: Cellular systems are introduced– 1990’s: Cellular industry becomes amongst fastest growing of all time.
• More advances in : – Radio, television, cellular technology, satellite communications, wireless
networking, etc.
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
The Evolution of Wireless Communications
• Joseph Henry
• James Clerk Maxwell
• Heinrich Hertz
• Ferdinand Braun
• Alexander Stepanovich Popov
• Julio Cervera Baviera
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• Édouard Branly
• Nikola Tesla
• Roberto Landell de Moura
• Oliver Joseph Lodge
• Jagadish Chandra Bose
• Ernest Rutherford
• Julio Cervera Baviera
• Guglielmo Marconi
• John Stone Stone
• Reginald Fessenden
• John Ambrose Fleming
• Lee De Forest
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Broadband Wireless Technology
• Higher data rates obtainable with broadband wireless technology.– Graphics, video, audio
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• Shares same advantages of all wireless services: convenience and reduced cost.– Service can be deployed faster than fixed service
– No cost of cable plant
– Service is mobile, deployed almost anywhere
• Many initiatives developing broadband wireless standards around many different applications.
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Limitations and Difficulties of Wireless Technologies
• Wireless is convenient and less expensive but there are limitations and political and technical difficulties inhibiting wireless technologies.
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• Lack of an industry-wide standard– slows technology growth
• Device limitations– size, power, etc
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
• Efficient Hardware– low power transmitters, receivers, signal processing tools
• Efficient use of finite radio spectrum
Limitations and Difficulties of Wireless TechnologiesLimitations and Difficulties of Wireless Technologies
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– frequency reuse, MAC protocols,...
• Integrated services– voice, data, multimedia over a single network
– service differentiation, priorities, resource sharing,...
• Network support for user mobility (mobile scenarios)– location identification, handover,...
– �maintaining quality of service over unreliable links
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Wireless Communication System Classifications
• Analogue - e.g. AM radio, FM radio, television, and 1G cellular systems.
• Digital (the source is assumed to be digital) - Every major
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• Digital (the source is assumed to be digital) - Every major wireless system being developed and deployed is built around digital communication e.g. cellular communication, WLANs, personal area networks, and high-definition television.
The focus of this class will be on digital wireless communication.
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Wireless Technologies
TVFM radio
AM radioBroadcast systems
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Wireless Local Area Networks
Bluetooth
Adhoc
Cellular systems
| University of Dar es Salaam | Department of Electronics and Telecommunications Engineering |__________________________________________________________________________________
Wireless Communications in Tanzania
• The evolution of wireless communications in Tanzania– History and evolution
– Key organisations and authorities
– Status of providers, consumers, standards, devices, applications
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– Status of providers, consumers, standards, devices, applications
• Mobile vs. fixed wireless communications in Tanzania – Penetration of devices
– Cost of devices and services
– Urban-rural coverage
– National strategies push, and international forces