Wireless and Mobile Technology-Introduction

Mobile Communications
Summer Term 2005 FU Berlin Computer Science Computer Systems & Telematics Prof. Dr.-Ing. Jochen Schiller http://www.jochenschiller.de/ [e-mail]
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 1.1

Overview of the lecture
Introduction
Use-cases, applications Definition of terms Challenges, history

Broadcast Systems
DAB, DVB

Wireless LANs
Basic Technology IEEE 802.11a/b/g, .15, Bluetooth

Wireless Transmission frequencies & regulations signals, antennas, signal propagation multiplexing, modulation, spread spectrum, cellular system

Network Protocols
Mobile IP Ad-hoc networking Routing

Media Access motivation, SDMA, FDMA, TDMA (fixed, Aloha, CSMA, DAMA, PRMA, MACA, collision avoidance, polling), CDMA

Transport Protocols
Reliable transmission Flow control Quality of Service

Wireless Telecommunication Systems
GSM, HSCSD, GPRS, DECT, TETRA, UMTS, IMT-2000

Support for Mobility
File systems, WWW, WAP, i-mode, J2ME, ...

Satellite Systems
GEO, LEO, MEO, routing, handover

Outlook

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

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Chapter 1:

Introduction

A case for mobility – many aspects History of mobile communication Market Areas of research

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

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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“)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 1.4

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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 1.5

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, ...

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

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Typical application: road traffic

UMTS, WLAN, DAB, DVB, GSM, cdma2000, TETRA, ...

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Personal Travel Assistant, PDA, Laptop, GSM, UMTS, WLAN, Bluetooth, ...
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Mobile and wireless services – Always Best Connected
GSM/GPRS 53 kbit/s Bluetooth 500 kbit/s UMTS, GSM 115 kbit/s LAN 100 Mbit/s, WLAN 54 Mbit/s

DSL/ WLAN 3 Mbit/s

UMTS 2 Mbit/s

GSM/EDGE 384 kbit/s, DSL/WLAN 3 Mbit/s GSM 115 kbit/s, WLAN 11 Mbit/s
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UMTS, GSM 384 kbit/s
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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

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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

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Mobile devices
Pager • receive only • tiny displays • simple text messages PDA • graphical displays • character recognition • simplified WWW Laptop/Notebook • fully functional • standard applications

Sensors, embedded controllers

Mobile phones • voice, data • simple graphical displays www.scatterweb.net Palmtop • tiny keyboard • simple versions of standard applications

performance
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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
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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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 1.13

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)

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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 1920

Wireless voice transmission New York - San Francisco 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

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History of wireless communication II
1928 1933 1958 many TV broadcast trials (across Atlantic, color TV, TV news) Frequency modulation (E. H. Armstrong) 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 1982 1983 1984

NMT at 450MHz (Scandinavian countries) Start of GSM-specification goal: pan-European digital mobile phone system with roaming

Start of the American AMPS (Advanced Mobile Phone System, analog) CT-1 standard (Europe) for cordless telephones

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

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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, ...

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

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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
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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,