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


Introduction Outline

• What is Wireless Communications

• The Evolution of Wireless Communications


• Broadband Wireless Technology

• Limitations and Difficulties of Wireless Technologies

• Wireless Communications in Tanzania


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


• where the distance between them is beyond usual voice or visual communication.

• Wireless Communications– Communicating information without wires

• using electromagnetic waves.


Wireless Communications

• Freedom from wires– No wires to install (cost), no bundles of wires around

• Global coverage


– 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


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)


• Mobile (e.g., GSM, cdma2000)


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.


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.


The Evolution of Wireless Communications

• Joseph Henry

• James Clerk Maxwell

• Heinrich Hertz

• Ferdinand Braun

• Alexander Stepanovich Popov

• Julio Cervera Baviera


• 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


Broadband Wireless Technology

• Higher data rates obtainable with broadband wireless technology.– Graphics, video, audio


• 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.


Limitations and Difficulties of Wireless Technologies

• Wireless is convenient and less expensive but there are limitations and political and technical difficulties inhibiting wireless technologies.


• Lack of an industry-wide standard– slows technology growth

• Device limitations– size, power, etc


• 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


– 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


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


• 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.


Wireless Technologies

TVFM radio

AM radioBroadcast systems


Wireless Local Area Networks

Bluetooth

Adhoc

Cellular systems


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


– 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

Documents

3. Introduction