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COM-405 Mobile Networks

Prof. Jean-Pierre Hubaux

http://mobnet.epfl.ch (redirected to Moodle)

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

- networking issues (MAC, network and transport layers, principally) -  estimation of network capacity and resource management -  wireless security/privacy issues

g  It does not cover: - radio propagation models - modulation and equalization techniques - source or channel coding - speech coding or other signal processing aspects - software-centric aspects (e.g., operating systems, mobile agents, smart

phone programming) g  It is focused on mechanisms, and avoids as much as possible a

detailed (and boring) description of standards g  However, it does propose an insight on IEEE 802.11 and on the

security of WLANs and cellular networks g  Acronyms are abundant and we have to cope with them… g  The course is also an attempt to get closer to the “real world” g  Heterogeneity of the audience

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Web site

http://mobnet.epfl.ch/

Of particular relevance: - Calendar -  Material (all slides used at the lectures, homeworks,…) -  Previous exams

Recommended book

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D. P. Agrawal and Q.-A. Zeng Introduction to Wireless and Mobile Systems Third Edition, 2011 Cengage (hard copy or e-book)

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Other Textbooks

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

- L. Buttyan and JP Hubaux: Security and Cooperation in Wireless Networks Cambridge University Press, 2008

http://secowinet.epfl.ch

- M. Schwartz: Mobile Wireless Communications Cambridge University Press, 2005

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Module A – Introduction (Part A1)

Wireless communication and mobility g  Aspects of mobility:

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

network

g  Wireless vs. mobile Examples û û stationary computer (desktop) û ü Cable-Internet laptop in a hotel ü û wireless LANs in historic buildings ü ü smart phone

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

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Examples of applications (1/2)

g  Person to person communication (e.g., voice, SMS) g  Person to server (e.g., location-based services, timetable

consultation, telebanking) g  Vehicles

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

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

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

maintenance g  Disaster situations

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

g  Military networks

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Upcoming application: road traffic

GSM, UMTS TETRA, ...

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

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Examples of applications (2/2)

g  Traveling salespeople direct access to customer files stored in a central location consistent databases for all agents mobile office

g  Replacement of fixed networks Sensors trade shows networks LANs in historic buildings

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

location dependent information ad-hoc networks for

multi user games Location-dependent advertising

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Location dependent services

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

local environment

g  Follow-on services transmission of the actual workspace to the current location

g  Information services „push“: e.g., current special offers in the shop nearby „pull“: e.g., where is the closest Migros?

g  Support services caches, intermediate results, state information etc. „follow“ the

mobile device through the fixed network

g  Location-Based Services (LBSs) Foursquare, Facebook Mobile,…

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Quad  band  GSM        (850,  900,  1800,  1900  MHz)  

 GPRS/EDGE  

 Tri  band  UMTS/HSDPA        (850,  1900,  2100  MHz)  

 LTE  (4G)  

 GPS  +  accelerometers  

 WiFi  (802.11b/g/a/n)  

 Bluetooth  

   

Modern mobile phones

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Wireless enabled devices

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Satellite Communications

BTCC-­‐45  Bluetooth  GPS  Receiver    

European  aTempt:  Galileo  

Global  PosiVoning  System  (GPS)  30  satellites  currently  

Orbit  alVtude:  approx.  20,200  km  Frequency:  1575.42  MHz  (L1)  

Bit-­‐rate:  50  bps  CDMA  

Iridium  9555  Satellite  Phone  

Supports  1100  concurrent  phone  calls  Orbit  alVtude:  approx.  780  km  

Frequency  band:  1616-­‐1626.5  MHz  Rate:  25  kBd  FDMA/TDMA  

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WiMAX  GP3500-­‐12  omnidirec6onal  antenna  

Frequency  band:  3400-­‐3600  MHz  Gain:  12  dBi  

Impendence:  50    Power  raVng:  10  WaT  

VerVcal  beamwidth:  10      

WiMAX  PA3500-­‐18  direc6onal  antenna  Frequency  band:  3200-­‐3800  MHz  

Gain:  12  dBi  Impendence:  50    

Power  raVng:  10  WaT  VerVcal  beamwidth:  17  

Horizontal  beamwidth:  20    

Wireless “Last Mile”: WiMax

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IEEE  802.15.4  Chipcon  Wireless  Transceiver  Frequency  band:  2.4  to  2.4835  GHz  

Data  rate:  250  kbps  RF  power:  -­‐24  dBm  to  0  dBm  

Receive  SensiVvity:  -­‐90  dBm  (min),  -­‐94  dBm  (typ)  Range  (onboard  antenna):  50m  indoors  /  125m  outdoors  

TelosB  Sensor  Mote  

MicaZ  

Imote2  

Wireless sensors

Iris  Mote  

Cricket  Mote  

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RFID  tag  

SDI  010  RFID  Reader  

ISO14443-­‐A  and  B  (13.56  MHz)  OperaVng  distance:  1cm  

CommunicaVon  speed:  up  to  848  Kbit/s  

Radio-frequency Identification (RFID)

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Implantable  Cardioverter  Defibrillator  (ICD)  

Medical Implants

OperaVng  frequency:  175kHz  Range:  few  cenVmeters  

Medical  Implant  CommunicaVon  Service  (MICS)  Frequency  band:  402-­‐405  MHz  

Maximum  transmit  power  (EIRP):  25  microwaT  Range:  few  meters  

 

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Vehicular communications

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Dedicated  short-­‐range  communica6ons  (DSRC)  Frequency  band  (US):  5.850  to  5.925  GHz  

Data  rate:  6  to  27  Mbps  Range:  up  to  1000m  

 

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Tuning  Frequency:  30KHz  -­‐  30MHz  (conVnuous)  

Tuning  Steps:  1/5/10/50/100/500Hz  &  1/5/9/10KHz  

Antenna  Jacket  /  Impedance:  BNC-­‐socket  /  50Ohms  

Max.  Allowed  Antenna  Level  :  +10dBm  typ.  /  saturaVon  at  -­‐15dBm  typ.  Noise  Floor  (0.15-­‐30MHz  BW  2.3KHz):  Standard:  <  -­‐131dBm  (0.06μV)  typ.  HighIP:  <  -­‐119dBm  (0.25μV)  typ.  

Frequency  Stability  (15min.  warm-­‐up  period):  

+/-­‐  1ppm  typ.    

Software Defined Radio

ApplicaVon:  CogniVve  Radios    è    Dynamic  Spectrum  Access    

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Mobile devices

performance

Pager •  receive only •  tiny displays •  simple text messages

Mobile phones •  voice, data •  web access •  location based services

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

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

wave ovens g  Restrictive regulations of frequencies

Usage of frequencies has to be coordinated, useful frequencies are almost all occupied (or at least reserved)

g  Lower transmission rates From a few kbit/s (e.g., GSM) to a 100s of Mbit/s (e.g. WLAN)

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

procedures g  Unknown location of the mobile station è mobility management

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History of wireless communication (1/3)

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

(Greece) 1794, optical telegraph, Claude Chappe

g  Electromagnetic waves are of special importance:

1831 Faraday demonstrates electromagnetic induction J. 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)

g  1895 Guglielmo Marconi first demonstration of wireless

telegraphy long wave transmission, high

transmission power necessary (> 200kw) g  1907 Commercial transatlantic connections

huge base stations (30 to 100m high antennas)

g  1915 Wireless voice transmission New York - San Francisco g  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)

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

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

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

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

Phone System, analog) g  1984 CT-1 standard (Europe) for cordless telephones g  1992 First deployment of GSM g  2002 First deployment of UMTS g  2010 - 2013 LTE standards mature, first trials

Wireless systems: development over the last 25 years

cellular phones satellites wireless LAN cordless phones

1992: GSM

1994: DCS 1800

2001: UMTS/IMT-2000

CDMA-2000 (USA)

1987: CT1+

1982: Inmarsat-A

1992: Inmarsat-B Inmarsat-M

1998: Iridium

1989: CT 2

1991: DECT 199x:

proprietary

1997: IEEE 802.11

1999: 802.11b, Bluetooth

1988: Inmarsat-C

analog

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

NMT: Nordic Mobile Telephone DECT: Digital Enhanced Cordless Telecom. AMPS: Advanced Mobile Phone System (USA) DCS: Digital Cellular System CT: Cordless Telephone PDC: Pacific Digital Cellular UMTS (3G): Universal Mobile Telecom. System PAN: Personal Area Network LTE (4G): Long Term Evolution UMA: Universal Mobile Access

2005: VoIP-DECT

2012 LTE

2009: IEEE 802.11n

2010 UMA

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Areas of research in mobile communication g  Wireless Communication

transmission quality (bandwidth, error rate, delay) modulation, coding, interference media access ...

g  Mobility location dependent services, also called location based services location transparency quality of service support (delay, jitter) security ...

g  Portability integration (“system on a chip”) power consumption limited computing power, sizes of display, ... usability ...

g  Security/privacy

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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

Radio link

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Influence of mobile communication on the layer model

location-dependent services new applications, multimedia adaptive applications congestion and flow control quality of service addressing, routing, mobility management hand-over media access multiplexing modulation power management, interference attenuation frequency allocation

g  Application layer

g  Transport layer

g  Network layer

g  Data link layer

g  Physical layer

security

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Overlay Networks - the global view

wide area

metropolitan area

campus-based

in-house

vertical hand-over

horizontal hand-over

Integration of heterogeneous fixed and mobile networks with varying transmission characteristics

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References (in addition to the recommended textbooks)

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

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

g  A. Goldsmith: Wireless Communications, Cambridge University Press, 2005

g  D. Tse and P. Viswanath: Fundamentals of Wireless Communication, Cambridge University Press, 2005