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Mobile Networking

Prof. Jean-Pierre Hubaux

http://mobnet.epfl.ch

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About this course

The course is about the system aspects of mobile networking Therefore, it covers:

networking issues (MAC and routing, principally)wireless security issuesestimation of network capacity and resource management

It does not cover:radio propagation modelsmodulation and equalization techniquessource or channel codingspeech coding or other signal processing aspectsSoftware-centric aspects (e.g., mobile agents)

It is focused on mechanisms, and avoids a detailed (and boring) description of standards

However, it does propose an insight on IEEE 802.11

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Course outline/calendar and textbook

http://mobnet.epfl.ch/index.php?page=calendar

http://www.inf.fu-berlin.de/inst/ag-tech/resources/mobkom/mobile_communications.htm

- J. Schiller: Mobile Communications, Second Edition Addison-Wesley, 2004

- W. Stallings: Wireless Communications & Networks, Second Edition, Prentice Hall, 2005

http://www.WilliamStallings.com/Wireless/Wireless2e.html

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Module A – Introduction(Part A1)

Wireless communication and mobility Aspects of mobility:

user mobility: users communicate “anytime, anywhere, with anyone”device portability: devices can be connected anytime, anywhere to the

network

Wireless vs. mobile Examples stationary computer (desktop) notebook in a hotel wireless LANs in historic buildings Personal Digital Assistant (PDA)

The demand for mobile communication creates the need for integration of wireless networks or mobility mechanisms into existing fixed networks:telephone network cellular telephony (e.g., GSM)local area networks Wireless LANs (e.g., IEEE 802.11)Internet Mobile IP

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Examples of applications (1/2)

Person to person communication (e.g., voice, SMS) Person to server (e.g., timetable consultation, telebanking) Vehicles

position via GPSlocal ad-hoc network with vehicles close-by to prevent accidents,

guidance system, adaptive cruise controltransmission of news, road condition, weather, music via Digital Audio

Broadcastingvehicle data (e.g., from buses, trains, aircrafts) transmitted for

maintenance Disaster situations

replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc.

Military networks

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Typical application: road traffic

ad ho

cGSM, UMTSTETRA, ...

http://ivc.epfl.chhttp://www.sevecom.org

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Examples of applications (2/2)

Traveling salespeopledirect access to customer files stored in a central locationconsistent databases for all agentsmobile office

Replacement of fixed networksSensorstrade shows networksLANs in historic buildings

Entertainment, education, ...outdoor Internet access travel guide with up-to-date

location dependent informationad-hoc networks for

multi user gamesLocation-dependent advertising

Built

150BC

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Location dependent services

Location aware serviceswhat services, e.g., printer, fax, phone, server etc. exist in the

local environment

Follow-on servicesautomatic call-forwarding, transmission of the actual

workspace to the current location

Information services„push“: e.g., current special offers in the shop nearby

„pull“: e.g., where is the closest Migros?

Support servicescaches, intermediate results, state information etc. „follow“ the

mobile device through the fixed network

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Mobile devices

performanceperformance

Pager• receive only• tiny displays• simple text messages

Mobile phones• voice, data• simple text displays

PDA• simple graphical displays• character recognition• simplified WWW

Laptop• functionally eq. to desktop• standard applications

Wireless sensors• Limited proc. power• Small battery

RFID tag• A few thousands of logical gates• Responds only to the RFID reader requests (no battery)

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Wireless networks in comparison to fixed networks

Higher data loss-rates due to notably to interferencesemissions of e.g., engines, lightning, other wireless networks, micro-

wave ovens Restrictive regulations of frequencies

Usage of frequencies has to be coordinated, useful frequencies are almost all occupied

Lower transmission ratesFrom a few kbit/s (e.g., GSM) to a few 10s of Mbit/s (e.g. WLAN)

Higher jitter Lower security (higher vulnerability) Radio link permanently shared need of sophisticated MAC Fluctuating quality of the radio links Unknown and variable access points authentication

procedures Unknown location of the mobile station mobility management

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History of wireless communication (1/3)

Many people in History used light for communicationheliographs, flags („semaphore“), ...150 BC smoke signals for communication

(Greece)1794, optical telegraph, Claude Chappe

Electromagnetic waves are of special importance:1831 Faraday demonstrates electromagnetic inductionJ. Maxwell (1831-79): theory of electromagnetic Fields, wave

equations (1864)H. Hertz (1857-94): demonstrates

with an experiment the wave character of electrical transmission through space(1886)

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History of wireless communication (2/3)

1895 Guglielmo Marconifirst demonstration of wireless

telegraphy

long wave transmission, high transmission power necessary (> 200kw)

1907 Commercial transatlantic connectionshuge base stations

(30 to 100m high antennas) 1915 Wireless voice transmission New York - San Francisco 1920 Discovery of short waves by Marconi

reflection at the ionosphere

smaller sender and receiver, possible due to the invention of the vacuum tube (1906, Lee DeForest and Robert von Lieben)

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History of wireless communication (3/3)

1928 Many TV broadcast trials (across Atlantic, color TV, TV news)

1933 Frequency modulation (E. H. Armstrong) 1946 First public mobile telephone service in 25 US cities

(1 antenna per city…) 1976 Bell Mobile Phone service for NY city 1979 NMT at 450MHz (Scandinavian countries) 1982 Start of GSM-specification

goal: pan-European digital mobile phone system with roaming 1983 Start of the American AMPS (Advanced Mobile

Phone System, analog) 1984 CT-1 standard (Europe) for cordless telephones 1992 Deployment of GSM 2002 Deployment of UMTS

Wireless systems: development over the last 25 years

cellular phones satellites wireless LANcordlessphones

1992:GSM

1994:DCS 1800

2001:UMTS/IMT-2000

CDMA-2000 (USA)

1987:CT1+

1982:Inmarsat-A

1992:Inmarsat-BInmarsat-M

1998:Iridium

1989:CT 2

1991:DECT 199x:

proprietary

1997:IEEE 802.11

1999:802.11b, Bluetooth

1988:Inmarsat-C

analogue

digital

1991:D-AMPS

1991:CDMA

1981:NMT 450

1986:NMT 900

1980:CT0

1984:CT1

1983:AMPS

1993:PDC

2000:GPRS

2000:IEEE 802.11a,g

2005 – 2010 (?):Fourth Generation(Internet based)

NMT: Nordic Mobile Telephone DECT: Digital Enhanced Cordless Telecom.AMPS: Advanced Mobile Phone System (USA) DCS: Digital Cellular SystemCT: Cordless Telephone PDC: Pacific Digital CellularUMTS: Universal Mobile Telecom. System PAN: Personal Area Network

What is missing ?

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Areas of research in mobile communication

Wireless Communicationtransmission quality (bandwidth, error rate, delay)modulation, coding, interferencemedia access...

Mobilitylocation dependent serviceslocation transparencyquality of service support (delay, jitter)security...

Portabilityintegration (“system on a chip”)power consumptionlimited computing power, sizes of display, ...usability...

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Reference model

Application

Transport

Network

Data Link

Physical

Data Link

Physical

Application

Transport

Network

Data Link

Physical

Data Link

Physical

Network Network

Radiolink

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Influence of mobile communication on the layer model

location-dependent services

new applications, multimediaadaptive applicationscongestion and flow controlquality of serviceaddressing, routing, mobility managementhand-overmedia accessmultiplexing

modulationpower management, interferenceattenuationfrequency allocation

Application layer

Transport layer

Network layer

Data link layer

Physical layer

security

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Overlay Networks - the global view

wide area

metropolitan area

campus-based

in-house

verticalhand-over

horizontalhand-over

Integration of heterogeneous fixed andmobile networks with varyingtransmission characteristics

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References (in addition to the 2 recommended textbooks)

B. Walke: Mobile Radio Networks, Wiley, Second Edition, 2002

T. Rappaport: Wireless Communications, Prentice Hall, Second Edition, 2001

M. Schwartz: Mobile Wireless Communications, Cambridge University Press, 2004

L. Buttyan and JP Hubaux: Security and Cooperation in Wireless Networks, Cambridge University Press, 2007, http://secowinet.epfl.ch