Mobile Communications: Mobile Communications Summer Term 2005 FU Berlin Computer Science Computer Systems & Telematics Prof. Dr.-Ing. Jochen Schiller http://www.jochenschiller.de/ schiller@computer.org


Overview of the lecture: Overview of the lecture Introduction Use-cases, applications Definition of terms Challenges, history Wireless Transmission frequencies & regulations signals, antennas, signal propagation multiplexing, modulation, spread spectrum, cellular system Media Access motivation, SDMA, FDMA, TDMA (fixed, Aloha, CSMA, DAMA, PRMA, MACA, collision avoidance, polling), CDMA Wireless Telecommunication Systems GSM, HSCSD, GPRS, DECT, TETRA, UMTS, IMT-2000 Satellite Systems GEO, LEO, MEO, routing, handover Broadcast Systems DAB, DVB Wireless LANs Basic Technology IEEE 802.11a/b/g, .15, Bluetooth Network Protocols Mobile IP Ad-hoc networking Routing Transport Protocols Reliable transmission Flow control Quality of Service Support for Mobility File systems, WWW, WAP, i-mode, J2ME, ... Outlook


Chapter 1:Introduction: Chapter 1: Introduction A case for mobility – many aspects History of mobile communication Market Areas of research


Computers for the next decades?: Computers for the next decades? Computers are integrated small, cheap, portable, replaceable - no more separate devices Technology is in the background computer are aware of their environment and adapt (“location awareness”) computer recognize the location of the user and react appropriately (e.g., call forwarding, fax forwarding, “context awareness”)) Advances in technology more computing power in smaller devices flat, lightweight displays with low power consumption new user interfaces due to small dimensions more bandwidth per cubic meter multiple wireless interfaces: wireless LANs, wireless WANs, regional wireless telecommunication networks etc. („overlay networks“)


Mobile communication: Mobile communication Two aspects of mobility: user mobility: users communicate (wireless) “anytime, anywhere, with anyone” device portability: devices can be connected anytime, anywhere to the network Wireless vs. mobile Examples   stationary computer   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 into existing fixed networks: local area networks: standardization of IEEE 802.11, ETSI (HIPERLAN) Internet: Mobile IP extension of the internet protocol IP wide area networks: e.g., internetworking of GSM and ISDN


Applications I: Applications I Vehicles transmission of news, road condition, weather, music via DAB personal communication using GSM position via GPS local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance Emergencies early transmission of patient data to the hospital, current status, first diagnosis replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc. crisis, war, ...


Typical application: road traffic: Typical application: road traffic ad hoc UMTS, WLAN, DAB, DVB, GSM, cdma2000, TETRA, ... Personal Travel Assistant, PDA, Laptop, GSM, UMTS, WLAN, Bluetooth, ...


Mobile and wireless services – Always Best Connected: Mobile and wireless services – Always Best Connected UMTS 2 Mbit/s UMTS, GSM 384 kbit/s LAN 100 Mbit/s, WLAN 54 Mbit/s UMTS, GSM 115 kbit/s GSM 115 kbit/s, WLAN 11 Mbit/s GSM/GPRS 53 kbit/s Bluetooth 500 kbit/s GSM/EDGE 384 kbit/s, DSL/WLAN 3 Mbit/s DSL/ WLAN 3 Mbit/s


Applications II: Applications II Travelling salesmen direct access to customer files stored in a central location consistent databases for all agents mobile office Replacement of fixed networks remote sensors, e.g., weather, earth activities flexibility for trade shows LANs in historic buildings Entertainment, education, ... outdoor Internet access intelligent travel guide with up-to-date location dependent information ad-hoc networks for multi user games History Info


Location dependent services: 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 supermarket „pull“: e.g., where is the Black Forrest Cherry Cake? Support services caches, intermediate results, state information etc. „follow“ the mobile device through the fixed network Privacy who should gain knowledge about the location


Mobile devices: Mobile devices performance Pager receive only tiny displays simple text messages Mobile phones voice, data simple graphical displays PDA graphical displays character recognition simplified WWW Palmtop tiny keyboard simple versions of standard applications Laptop/Notebook fully functional standard applications Sensors, embedded controllers www.scatterweb.net


Effects of device portability: Effects of device portability Power consumption limited computing power, low quality displays, small disks due to limited battery capacity CPU: power consumption ~ CV2f C: internal capacity, reduced by integration V: supply voltage, can be reduced to a certain limit f: clock frequency, can be reduced temporally Loss of data higher probability, has to be included in advance into the design (e.g., defects, theft) Limited user interfaces compromise between size of fingers and portability integration of character/voice recognition, abstract symbols Limited memory limited value of mass memories with moving parts flash-memory or ? as alternative


Wireless networks in comparison to fixed networks: Wireless networks in comparison to fixed networks Higher loss-rates due to interference emissions of, e.g., engines, lightning Restrictive regulations of frequencies frequencies have to be coordinated, useful frequencies are almost all occupied Low transmission rates local some Mbit/s, regional currently, e.g., 53kbit/s with GSM/GPRS Higher delays, higher jitter connection setup time with GSM in the second range, several hundred milliseconds for other wireless systems Lower security, simpler active attacking radio interface accessible for everyone, base station can be simulated, thus attracting calls from mobile phones Always shared medium secure access mechanisms important


Early history of wireless communication : Early history of wireless communication Many people in history used light for communication heliographs, flags („semaphore“), ... 150 BC smoke signals for communication; (Polybius, Greece) 1794, optical telegraph, Claude Chappe Here 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 (1888, in Karlsruhe, Germany, at the location of today’s University of Karlsruhe)


History of wireless communication I: History of wireless communication I 1896 Guglielmo Marconi first demonstration of wireless telegraphy (digital!) long wave transmission, high transmission power necessary (> 200kw) 1907 Commercial transatlantic connections huge base stations (30 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) 1926 Train-phone on the line Hamburg - Berlin wires parallel to the railroad track


History of wireless communication II: History of wireless communication II 1928 many TV broadcast trials (across Atlantic, color TV, TV news) 1933 Frequency modulation (E. H. Armstrong) 1958 A-Netz in Germany analog, 160MHz, connection setup only from the mobile station, no handover, 80% coverage, 1971 11000 customers 1972 B-Netz in Germany analog, 160MHz, connection setup from the fixed network too (but location of the mobile station has to be known) available also in A, NL and LUX, 1979 13000 customer in D 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


History of wireless communication III: History of wireless communication III 1986 C-Netz in Germany analog voice transmission, 450MHz, hand-over possible, digital signaling, automatic location of mobile device Was in use until 2000, services: FAX, modem, X.25, e-mail, 98% coverage 1991 Specification of DECT Digital European Cordless Telephone (today: Digital Enhanced Cordless Telecommunications) 1880-1900MHz, ~100-500m range, 120 duplex channels, 1.2Mbit/s data transmission, voice encryption, authentication, up to several 10000 user/km2, used in more than 50 countries 1992 Start of GSM in D as D1 and D2, fully digital, 900MHz, 124 channels automatic location, hand-over, cellular roaming in Europe - now worldwide in more than 200 countries services: data with 9.6kbit/s, FAX, voice, ...


History of wireless communication IV: History of wireless communication IV 1994 E-Netz in Germany GSM with 1800MHz, smaller cells As Eplus in D (1997 98% coverage of the population) 1996 HiperLAN (High Performance Radio Local Area Network) ETSI, standardization of type 1: 5.15 - 5.30GHz, 23.5Mbit/s recommendations for type 2 and 3 (both 5GHz) and 4 (17GHz) as wireless ATM-networks (up to 155Mbit/s) 1997 Wireless LAN - IEEE802.11 IEEE standard, 2.4 - 2.5GHz and infrared, 2Mbit/s already many (proprietary) products available in the beginning 1998 Specification of GSM successors for UMTS (Universal Mobile Telecommunication System) as European proposals for IMT-2000 Iridium 66 satellites (+6 spare), 1.6GHz to the mobile phone


History of wireless communication V: History of wireless communication V 1999 Standardization of additional wireless LANs IEEE standard 802.11b, 2.4-2.5GHz, 11Mbit/s Bluetooth for piconets, 2.4Ghz, <1Mbit/s Decision about IMT-2000 Several “members” of a “family”: UMTS, cdma2000, DECT, … Start of WAP (Wireless Application Protocol) and i-mode First step towards a unified Internet/mobile communicaiton system Access to many services via the mobile phone 2000 GSM with higher data rates HSCSD offers up to 57,6kbit/s First GPRS trials with up to 50 kbit/s (packet oriented!) UMTS auctions/beauty contests Hype followed by disillusionment (50 B$ payed in Germany for 6 licenses!) 2001 Start of 3G systems Cdma2000 in Korea, UMTS tests in Europe, Foma (almost UMTS) in Japan


Wireless systems: overview of the development: Wireless systems: overview of the development cellular phones satellites wireless LAN cordless phones 1992: GSM 1994: DCS 1800 2001: IMT-2000 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 analogue digital 1991: D-AMPS 1991: CDMA 1981: NMT 450 1986: NMT 900 1980: CT0 1984: CT1 1983: AMPS 1993: PDC 4G – fourth generation: when and how? 2000: GPRS 2000: IEEE 802.11a 200?: Fourth Generation (Internet based)


Foundation: ITU-R - Recommendations for IMT-2000: Foundation: ITU-R - Recommendations for IMT-2000 M.687-2 IMT-2000 concepts and goals M.816-1 framework for services M.817 IMT-2000 network architectures M.818-1 satellites in IMT-2000 M.819-2 IMT-2000 for developing countries M.1034-1 requirements for the radio interface(s) M.1035 framework for radio interface(s) and radio sub-system functions M.1036 spectrum considerations M.1078 security in IMT-2000 M.1079 speech/voiceband data performance M.1167 framework for satellites M.1168 framework for management M.1223 evaluation of security mechanisms M.1224 vocabulary for IMT-2000 M.1225 evaluation of transmission technologies . . . http://www.itu.int/imt


Worldwide wireless subscribers (old prediction 1998): Worldwide wireless subscribers (old prediction 1998) 0 100 200 300 400 500 600 700 1996 1997 1998 1999 2000 2001 Americas Europe Japan others total


Mobile phones per 100 people 1999: Mobile phones per 100 people 1999 Finland Sweden Norway Denmark Italy Luxemburg Portugal Austria Ireland Switzerland Great Britain Netherlands France Belgium Spain Greece Germany 2005: 70-90% penetration in Western Europe


Worldwide cellular subscriber growth: Worldwide cellular subscriber growth Note that the curve starts to flatten in 2000 – 2004: 1.5 billion users


Cellular subscribers per region (June 2002): Cellular subscribers per region (June 2002) 2004: 715 million mobile phones delivered


Mobile statistics snapshot (09/2002 / 12/2004): Mobile statistics snapshot (09/2002 / 12/2004) Total Global Mobile Users 869M / 1.52bn Total Analogue Users 71M / 34m Total US Mobile users 145M / 140m Total Global GSM users 680M / 1.25T Total Global CDMA Users 127M / 202m Total TDMA users 84M / 120m Total European users 283M / 343m Total African users 18.5M / 53m Total 3G users 130M / 130m(?) Total South African users 13.2m / 19m European Prepaid Penetration 63% European Mobile Penetration 70.2% Global Phone Shipments 2001 393m Global Phone Sales 2Q02 96.7m http://www.cellular.co.za/stats/stats-main.htm #1 Mobile Country China (139M / 300m) #1 GSM Country China (99m) #1 SMS Country Philipines #1 Handset Vendor 2Q02 Nokia (37.2%) #1 Network In Africa Vodacom (6.6m) #1 Network In Asia Unicom (153m) #1 Network In Japan DoCoMo #1 Network In Europe T-Mobile (22m / 28m) #1 In Infrastructure Ericsson SMS Sent Globally 1Q02 60T / 135bn SMS sent in UK 6/02 1.3T / 2.1bn SMS sent Germany 1Q02 5.7T GSM Countries on Air 171 / 210 GSM Association members 574 / 839 Total Cost of 3G Licenses in Europe 110T€ SMS/month/user 36 The figures vary a lot depending on the statistic, creator of the statistic etc.!


Areas of research in mobile communication: Areas of research in mobile communication Wireless Communication transmission quality (bandwidth, error rate, delay) modulation, coding, interference media access, regulations ... Mobility location dependent services location transparency quality of service support (delay, jitter, security) ... Portability power consumption limited computing power, sizes of display, ... usability ...


Simple reference model used here: Simple reference model used here Application Transport Network Data Link Physical Medium Data Link Physical Application Transport Network Data Link Physical Data Link Physical Radio


Influence of mobile communication to the layer model: Influence of mobile communication to the layer model service location new applications, multimedia adaptive applications congestion and flow control quality of service addressing, routing, device location hand-over authentication media access multiplexing media access control encryption modulation interference attenuation frequency Application layer Transport layer Network layer Data link layer Physical layer


Overview of the main chapters: Overview of the main chapters Chapter 2: Wireless Transmission Chapter 3: Medium Access Control Chapter 4: Telecommunication Systems Chapter 5: Satellite Systems Chapter 6: Broadcast Systems Chapter 7: Wireless LAN Chapter 8: Mobile Network Layer Chapter 9: Mobile Transport Layer Chapter 10: Support for Mobility


Overlay Networks - the global goal: Overlay Networks - the global goal regional metropolitan area campus-based in-house vertical handover horizontal handover integration of heterogeneous fixed and mobile networks with varying transmission characteristics