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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