1 Mobile Networking Prof. Jean-Pierre Hubaux

2 About this course  The course is about the system aspects of mobile networking  Therefore, it covers: networking issues (MAC and routing, principally) wireless security issues estimation of network capacity and resource management  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., mobile agents)  It is focused on mechanisms, and avoids a detailed (and boring) description of standards  However, it does propose an insight on IEEE

3 Course outline/calendar and textbook J. Schiller: Mobile Communications, Second Edition Addison-Wesley, W. Stallings: Wireless Communications & Networks, Second Edition, Prentice Hall,

4 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 ) Internet  Mobile IP

6 Examples of applications (1/2)  Person to person communication (e.g., voice, SMS)  Person to server (e.g., timetable consultation, telebanking)  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  Disaster situations replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc.  Military networks

7 Typical application: road traffic ad hoc GSM, UMTS TETRA,

8 Examples of applications (2/2)  Traveling salespeople direct access to customer files stored in a central location consistent databases for all agents mobile office  Replacement of fixed networks Sensors trade shows networks LANs in historic buildings  Entertainment, education,... outdoor Internet access travel guide with up-to-date location dependent information ad-hoc networks for multi user games Location-dependent advertising Built 150BC

9 Location dependent services  Location aware services what services, e.g., printer, fax, phone, server etc. exist in the local environment  Follow-on services automatic 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 services caches, intermediate results, state information etc. „follow“ the mobile device through the fixed network

10 Mobile devices performance 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)

11 Wireless networks in comparison to fixed networks  Higher data loss-rates due to notably to interferences emissions 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 rates From 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

12 History of wireless communication (1/3)  Many people in History used light for communication heliographs, flags („semaphore“), BC smoke signals for communication (Greece) 1794, optical telegraph, Claude Chappe  Electromagnetic waves are of special importance: 1831 Faraday demonstrates electromagnetic induction J. Maxwell ( ): theory of electromagnetic Fields, wave equations (1864) H. Hertz ( ): demonstrates with an experiment the wave character of electrical transmission through space (1886)

13 History of wireless communication (2/3)  1895 Guglielmo Marconi first demonstration of wireless telegraphy long wave transmission, high transmission power necessary (> 200kw)  1907 Commercial transatlantic connections huge 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)

14 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 phonessatellites wireless LANcordless phones 1992: GSM 1994: DCS : UMTS/IMT-2000 CDMA-2000 (USA) 1987: CT : Inmarsat-A 1992: Inmarsat-B Inmarsat-M 1998: Iridium 1989: CT : DECT 199x: proprietary 1997: IEEE : b, Bluetooth 1988: Inmarsat-C analogue digital 1991: D-AMPS 1991: CDMA 1981: NMT : NMT : CT0 1984: CT1 1983: AMPS 1993: PDC 2000: GPRS 2000: IEEE a,g 2005 – 2010 (?): Fourth Generation (Internet based) NMT: Nordic Mobile TelephoneDECT: Digital Enhanced Cordless Telecom. AMPS: Advanced Mobile Phone System (USA)DCS: Digital Cellular System CT: Cordless TelephonePDC: Pacific Digital Cellular UMTS: Universal Mobile Telecom. SystemPAN: Personal Area Network What is missing ?

16 Areas of research in mobile communication  Wireless Communication transmission quality (bandwidth, error rate, delay) modulation, coding, interference media access...  Mobility location dependent services location transparency quality of service support (delay, jitter) security...  Portability integration (“system on a chip”) power consumption limited computing power, sizes of display,... usability...

17 Reference model Application Transport Network Data Link Physical Data Link Physical Application Transport Network Data Link Physical Data Link Physical Network Radio link

18 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  Application layer  Transport layer  Network layer  Data link layer  Physical layer security

19 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

20 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,