Redes Inalámbricas – Tema 1 General concepts

REDES INALÁMBRICAS Máster de Ingeniería de Computadores-DISCA

Redes Inalámbricas – Tema 1 General concepts

An overall view of: Technologies MANETs networks Applications Devices References

Acknowledgments Mark Weiser Vint Cerf Jim Kurose, Keith Ross, “Computer Networking: A Top Down Approach Featuring the Internet,

2nd edition. Addison-Wesley, July 2002



Technologies

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10 Various types of wireless technologies WiMax WiFi Bluetooth Network telephony. Various

generations: GSM GPRS, EDGE; UMTS HSDPA LTE

Satellites: Satellites Geostationary Earth Orbit

(GEO) Example: Inmarsat

Satellites Low-Earth Orbit (LEO) Example : Iridium (66 satellites)

(2.4 Kbps data) Infrared: IrDA Ultra-Wide Band (UWB) RFID Zigbee …

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10 Wireless Data Networks

Wireless networks are the best option for mobile devices: Easy installation: no problems with cables Systems easily expandable according to the needs

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Local AreaPersonal Area Wide Area

Wireless LAN

IEEE 802.11

PANBluetooth

Cellular Systems

GSM, GPRS, EDGE

UMTS

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10 Uses of WLANs5

• COMMON AREAS,• MEETING ROOMS,• LABORATORIES,

• TEMPORARY OFFICE

“CORPORATE CAMPUS”

• AIRPORTS• HOTELS

• CONVENTION CENTER

“HOME OFFICE”

“HOT SPOTS”

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10 Uses of WPAN6

DSC

HDTV

STB/Media Center

PC

Photo/Printer

Mobile/Smart HH

Mass Storage

Substitute cablesPersonal ad hoc connectivity

KB, Mouse

DVCVoice, Stereo Audio

BT Model UWB Model

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10 Mobility

There are several types of mobility Physical mobility (of the devices)

off line connectivity: portable on line connectivity : mobile

Logical mobility: Of the processes Of the applications “ubiquitous computing”

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10 Mobility and the applications Bandwidth variability

Applications should adapt. E.g., a videoconferencing application could vary the image size or its quality when varying the bandwidth.

Disconnection Allow asynchronous operations, pre-fetching, caching, weak

consistency, ... Security and privacy

The wireless channels are prone to "wiretapping''(snooping) Who should be given access to the location information? How much

accurate should be this information? Energy management:

stop discs, turn off the screen, standby mode of the CPU, put to sleep the network card, …

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10 General view9

“Mobile ad hoc networking: imperatives and challenges”, Imrich Chlamtac, Marco Conti, Jennifer J.-N. Liu, Ad Hoc Networks, Elsevier, 1 (2003).



Devices

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10 Sensors11

Mica Hardware Platform: The Mica sensor node (left) with the Mica Weather Board developed for environmental monitoring applications

http://images.google.com/imgres?imgurl=robotics.eecs.berkeley.edu/~pister/SmartDust/5mmmote.jpg&imgrefurl=http://robotics.eecs.berkeley.edu/~pister/SmartDust/&h=220&w=162&sz=11&tbnid=G1WTOjVi91kJ:&tbnh=101&tbnw=75&prev=/images?q=smart+dust&hl=es&lr

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10 Mobile devices: PDA and phones12

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10 Mobile devices: notebooks/laptops13

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10 Mobile devices : tablet PC14

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10 More devices (Information/Internet Appliances)15

World’s smallest web serverhttp://www.webservusb.com/

IP picture framehttp://www.ceiva.com/

Web-enabled toaster+weather forecaster

Screenfridge

http://www.electrolux.com/screenfridge/

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10 More devices (Information/Internet Appliances)16



MANETs networks

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10 Mobile Ad-hoc Networks (MANETs)

Networks formed by mobile wireless nodes. Do not use any existing infrastructure

There are hybrid solutions known as "mesh networks“ In a MANET mobility has a crucial importance.

routes vary over time partitioning

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10 Why ad hoc networks?

The ad hoc networks can be deployed in a flexible manner in environments that have no fixed infrastructure

Having a fixed wired infrastructure or access points is not always possible or feasible It is not economically viable or interesting It is not practical in temporary environments It may have been destroyed, for example, due to natural disasters

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10 A “clear” example: vehicular networks About “smart cars” and “smart

roads”. On-board systems “talk” with the “road”.

They car offer: Cooperative driver assistance:

Emergency notification Overtaking assistance Obstacle warning

Decentralized floating car data: Traffic jam monitor Dynamic navigation Route weather forecast

User communications and information services:

Hot-spot Internet access Inter-vehicle chat Distributed games

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Applications: UBIQUITOUS COMPUTING

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10 Ubiquitous Computing

Mark Weiser – The father of “Ubiquitous Computing” (1988)

Definitions Ubiquitous computing is the method of enhancing computer use by

making many computers available throughout the physical environment, but making them effectively invisible to the user

– Mark Weiser

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Mark Weiser (1952-1999) was the chief technology officer at Xerox’s Palo Alto Research Center (Parc). He is often referred to as the father of ubiquitous computing. He coined the term in 1988 to describe a future in which invisible computers, embedded in everyday objects, replace PCs. Other research interests included garbage collection, operating systems, and user interface design. He received his MA and PhD in computer and communication science at the University of Michigan, Ann Arbor. After completing his PhD, he joined the computer science department at the University of Maryland, College Park, where he taught for 12 years. He wrote or cowrote over 75 technical publications on such subjects as the psychology of programming, program slicing, operating systems, programming environments, garbage collection, and technological ethics. He was a member of the ACM, IEEE Computer Society, and American Association for the Advancement of Science. Weiser passed away in 1999. Visit www.parc.xerox.com/csl/members/weiser or contact [email protected] for more information about him.

Mark Weiser (1952-1999)

http://www-sul.stanford.edu/weiser/ M. Weiser, The Computer for the 21st Century Scientific American, 1991

http://www.parc.xerox.com/csl/members/weiser

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1023 Ubiquitous Computing

What Ubiquitous Computing is: Information technology everywhere

Is a paradigm shift where technology becomes virtuallyinvisible in our lives “Calm Technology”

It needsSmart Objects embedded processorsWireless Technology to interconnect them

What Ubiquitous Computing is not: Mobility itself doesn’t lead to UbiComp Multimedia itself doesn’t lead to UbiComp either Virtual reality neither

Ubiquitous Computing: And old vision

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1024 The new paradigm

Generic Features “Invisible” interfaces that

provideinteraction between user and application

Awareness of context Context information about the

environment with which theapplication is associated.

LOCATION and TIME are simple examples of context !

Capture experience To capture our day-to-day

experience and make it available for future use.

To acquires knowledge from places visited to server future visitors

Research challenges Multiple streams of information Their time synchronization Their correlation and integration

TransparentInterfaces

Awareness ofContext(s)

Capture Experience

Environment Preferences

AutoDiary CAApp

Context Data LayerContext Data Layer

Sour

ces

Sink

sSp

aces

Sensor

PublicDisplay

ManualInput

ContextBrowser

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10 More examples at MIT25

http://ttt.media.mit.edu/

http://ttt.media.mit.edu/research/research.html



Applications: RURAL COMMUNICATIONS

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10 Global survey on rural communications

Rural communications on the global agenda Connecting villages with Information and Communication Technologies

(ICT) and establishing community access points Benefits

E-business and e-commerce could play an important role in enabling local artisans to reach national and international markets

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Yasuhiko Kawasumi, “Rural communications on the global agenda,” Global Survey on Rural Communications for the ITU-D on Communications for rural and remote areas.

Over 40% of the world’s population lives in rural and remote areas of developing countries and have difficult or no access to even basic telecommunications services. Development of telecommunications in rural and remote areas, therefore forms an important mission of the ITU Development sector.

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10 Rural populations and their ICT needs

Needs of rural people in connection with e-services E-health, e-education and e-administration top the list as primary needs E-business and e-banking also scored highly

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ITU-D global survey, Doc 111/SG2

For many rural areas, electricity supply is simply non-existent or insufficient

Telemedicine Training in Bhutan by Tokai University: Tokai University Institute of Medical Sciences donated the medical equipments with ICT functions and provided the training on the use of equipments. Tokai University Second Opinion center provides the assistance service over the internet when requested by the Bhutanese ends.

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10Optimal Technologies to connect Rural

Communities Question 1: What are the requirements for communications

system in rural areas Implementation should be possible at a low cost in areas where

population density is low The system can be easily installed, even in remote and inaccessible

locations System operation and maintenance may be carried out even where

qualified technical personnel are scarce Implementation should be possible even when basic infrastructure such

as mains electricity, running water, paved road networks, etc., are absent

Long life cycles

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Communities Question 2: What are the choices of technologies for

communications in rural areas Satellite communications system (VSAT) Terrestrial wireless communications system

Wi-Fi, Wi-Max, 802.16 Mobile communications system (2G,GSM) Copper wire including power line The final report of ITU Focus Group 7 on “New

technologies for rural applications” (2001) recommended (WiFi) based on the IEEE 802.11 b/g

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Communities Question 3: What is the advantage of wireless technologies for

communications in rural areas Provide significant life time cost benefits in rural areas in cases where

cable deployment is uneconomic. Provide easy and speedy installation in harsh terrain and extremely

remote areas, smaller investment increments and avoidance of copper cable theft.

Provide lower maintenance cost and greater network flexibilities

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Communities Question 4: What are the barriers for communications in the

environment of rural areas Scarcity and absence of reliable electricity supply, water, access roads

and regular transport Scarcity of technical personnel Difficult topographical conditions (lakes, rivers, hills, mountains, or

deserts, etc.) Severe climatic conditions that make critical demands on the

equipment. Low level of economic activity mainly based on agriculture, fishing,

handicrafts, etc. Low per capita income Underdeveloped social infrastructure (health, education) Low population density Low literacy rate

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1033 El Programa Telecentros

¿Qué es? El programa Telecentros se ha dirigido a los municipios de zonas rurales y a

núcleos urbanos desfavorecidos, a través de las Diputaciones, Cabildos y Consejos insulares o, en su caso, Comunidades Autónomas uniprovinciales. La actuación tuvo como principal objetivo facilitar el acceso a las nuevas tecnologías tanto a las poblaciones rurales como a los colectivos menos integrados, a fin de lograr su participación efectiva en la Sociedad de la Información.

La actuación tiene como principal objetivo facilitar el acceso a las nuevas tecnologías tanto a las poblaciones rurales como a los colectivos menos integrados, a fin de lograr su participación efectiva en la Sociedad de la Información.

Actuaciones: Conexiones a Internet de banda ancha en zonas rurales

y urbanas desfavorecidas. Equipamiento de los Centros de Acceso Público a Internet. Servicios de instalación, mantenimiento y atención al usuario. Servicios de control y gestión del Centro. Portales de servicios a poblaciones rurales. Servicios de dinamización y formación

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1034 EU y las redes rurales

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10 Mesh Networks

Features Multi-hop Networks Automatic organization and maintenance Support for mobility (clients) Integration of technology access

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10 MIT Roofnet

MIT Roofnet: http://pdos.csail.mit.edu/roofnet/doku.php Wireless access to the MIT Computer Science Lab

1,25 squared miles

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MIT Roofnet: Distribution of nodes

and quality of the links

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1037 guifi.net

Public WiFi network deployed basically in Cataluña

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10 Other proposals

Kingsbridge Link http://www.kblink.co.uk/ Based on Linksys WRT54g

panOULU http://www.panoulu.net/ Finland

Meraki http://meraki.com/ San Francisco

Fon http://www.fon.com/es/

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http://www.panoulu.net/



Applications: VANETs

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10 Motivation

Safety and transport efficiency In Europe around 40,000 people die and more than 1.5 millions are

injured every year on the roads Traffic jams generate a tremendous waste of time and of fuel

Most of these problems can be solved by providing appropriate information to the driver or to the vehicle

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10 Passive Approach is not Enough41

What’s in front of

that bus ?

What’s behind the

bend ?On rainy days

On foggy days

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10 Vehicle Communication (VC)

VC promises safer roads,

… more efficient driving,

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10 Vehicle Communication (VC)

… more fun,

… and easier maintenance.

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10 Lot of Involved Technologies44

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10 Lot of Involved Parties45

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1046 VANETs vs MANETs

Vehicular ad-hoc network (VANET) are a special case of Mobile ad-hoc networks (MANET) VANET constrained by

Predefined roads (e.g. one-way and multi-lane)Vehicle velocities restricted by speed limitsLevel of congestion in roads (e.g. urban or suburban)Traffic control mechanisms (e.g. traffic light)

VANET advantage by Rechargeable source of energyEquipped with devices with potentially longer transmission ranges.

(e.g. adopt WAVE and WiMAX) etc.

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1047 VANETs vs MANETs

Rapid Topology Changes High relative speed of vehicles => short link life

Frequent Fragmentation Chunks of the net are unable to reach nodes in nearby regions

Small Effective Network Diameter A path may cease to exist almost as quickly as it was discovered

(reactive routing) Limited Redundancy

The redundancy in MANETs is critical to providing additional bandwidth In VANETs the redundancy is limited both in time and in function


Redes Inalámbricas – Tema 1General concepts

References

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1049 References

Bibliografía Básica / Basic book The basic reference book for this course is "Wireless Networking in the

Developing World". This is a free book about designing, implementing, and maintaining low-cost wireless networks.

Reference books about advanced topics: "Wireless Communications: Principles and Practice (2nd Edition)",

Theodore S. Rappaport, Prentice Hall, January 2002. Available via Safari. "802.11 Wireless Networks: The Definitive Guide, Second Edition",

Matthew Gast, O'Reilly, April 2005. Available via Safari. "Ad Hoc Mobile Wireless Networks: Protocols and Systems", C. K. Toh,

Prentice Hall, 2001. Available via Safari. "Ad Hoc Wireless Networks Architectures and Protocols", C. Siva Ram

Murthy; B. S. Manoj, Prentice Hall, 2004. Available via Safari. Documentación adicional para matriculados UPV

Disponible en Poliformat

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10 Standards en Internet de-facto standards

“Rough consensus and running code”, D. Clark Defined in documents called RFCs (Request For Comments) available on

line: http://www.rfc-editor.org/

Phases: Proposed standards Draft Standard Internet Standard Before getting to RFC we use Internet-Drafts which are working

documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. https://datatracker.ietf.org/drafts/

50

(Internet Architecture Board)IAB

IRTF IETF

1983

1989

Internet Society~1991

http://www.rfc-editor.org/

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1051 Where to find up-to-date research references

Journals and Magazines: IEEE Network Magazine IEEE Communications Magazine IEEE Wireless Communications Magazine IEEE Pervasive Computing IEEE/ACM Transactions on Networking (TON) IEEE Transactions on Mobile Computing IEEE Journal on Selected Areas of Communications (JSAC)

Conferences: MOBICOM, MOBIHOC, PIMRC, MWCN... ICC, ISCC, ICCN GLOBECOM INFOCOM SIGCOMM

WWW http://www.grc.upv.es/links/ Web pages of research groups Google…

Redes Inalámbricas – Tema 1 General concepts

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