Mobile Computing Computer Science · 2/4/2009 · Thanks to Jochen Schiller and Roger Wattenhofer...

Western Michigan UniversityComputer Science

Mobile Computing

Prof. Ajay Gupta, 2004 1.1

Ajay Gupta Mobile Communications, Computing and Systems CS603 Fall2004 WMU-CS 1.1

Source: Schiller’s MobiComm book, Wattenhoffer@ETH-Z notes, Pitoura & Samaras’ Data Mgmt for Mobile Computing book, Agrawal & Zeng’s WMS book, Stalling’s WCN book

CS603

Mobile ComputingFall 2004

Computer ScienceWestern Michigan University

Ajay Gupta

http://www.cs.wmich.edu/[email protected]

Thanks to Jochen Schiller and Roger Wattenhofer for slides



Constraints of Mobility

! Mobile elements are resource-poor relative to static elements

! Mobility is inherently hazardous

! Mobile connectivity is highly variable in performance and reliability

! Mobile elements rely on a finite energy source



Application Scenarios

! Vehicles

! Nomadic user

! Smart mobile phone! Invisible computing

! Wearable computing

! Intelligent house or office

! Meeting room / conference! Taxi/police/fire squad fleet

! Service worker

! Lonely wolf

! Disaster relief and disaster alarm! Games

! Military / security

What is important?



Typical application: road traffic

ad ho

cUMTS, WLAN,DAB, GSM, cdma2000, TETRA, ...

Personal Travel Assistant,DAB, PDA, laptop, GSM, UMTS, WLAN, Bluetooth, ...


Mobile Computing




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, ...



TSP: Mobile and wireless services – Always Best Connected

UMTS,DECT2 Mbit/s

UMTS, GSM384 kbit/s

LAN100 Mbit/s,WLAN54 Mbit/s

UMTS, GSM115 kbit/s

GSM 115 kbit/s,WLAN 11 Mbit/s

GSM 53 kbit/sBluetooth 500 kbit/s

GSM/EDGE 384 kbit/s,WLAN 780 kbit/s

LAN, WLAN780 kbit/s



Applications II

Traveling 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

HistoryInfo



Nomadic user

Nomadic user has laptop/palmtop

Connect to network infrequently

Interim period operate in disconnected modeAccess her or customer data

Consistent database for all agents

Print on local printer (or other service)! How do we find it?! Is it safe?! Do we need wires?

Does nomadic user need her own hardware?• Read/write email on web browser• Access data OK too


Mobile Computing




Built

150BC

Smart mobile phone

Mobile phones get smarter

Converge with PDA?Voice calls, video calls (really?)

Email or instant messaging

Play games

Up-to-date localized information! Map! Pull: Find the next Pizzeria! Push: “Hey, we have great Pizza!”

Stock/weather/sports info

TicketingTrade stock

etc.

[Nokia]

[J. Schiller]



Invisible/ubiquitous/pervasive and wearable computing

Tiny embedded “computers”

EverywhereExample: Microsoft’s Doll

I refer to my colleaguesand courses in

Sensor Networks, Embedded Systems, …

[ABC, Schiele]



Intelligent Office and Intelligent House

Bluetooth replaces cables

Plug and play, without the “plug”Again: Find the local printer

House recognizes inhabitant

House regulates temperature according to person in a room

Trade ShowsHome without cables looks better

LAN in historic buildings [MS]



Meeting room or Conference

Share data instantly

Send a message to someone else in the room

Secretly vote on controversial issue

Find person with similar interestsBroadcast last minute changes

Ad-Hoc Network


Mobile Computing




Taxi / Police / Fire squad / Service fleet

Connect

ControlCommunicate

Service Worker

Example: SBC service workers have PDA! Map help finding broken signal! PDA gives type of signal, so that

service person can bring the right tools right away



Lonely wolf

We really mean everywhere!

Cargo’s and yachts

Journalists

Scientists

Travelers

Sometimes cheaper than infrastructure?

Commercial flop [Motorola]



Disaster relief

After earthquake, tsunami, volcano, etc:

You cannot rely on infrastructure but you need to orchestrate disaster relief

Early transmission of patient data to hospital

Satellite

Ad-Hoc network[Red Cross]



Disaster alarm

With sensors you might be able to alarm early

Example: Tsunami

Example: Cooling room

Or simpler: Weather station

Satellite

Ad-Hoc network


Mobile Computing




Games

Nintendo Gameboy [Advance]: Industry standard mobile game station

Connectable to other GameboysCan be used as game pad for

Nintendo Gamecube

Cybiko [Extreme] is a competitor that has radio capabilities built in

Second generation already

Also email, chat, etc.[Cybiko]



Military / Security

From a technology standpoint this is similar to disaster relief

Sensoria says “US army is the best costumer”

Not much in this course



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



Application Scenarios: Discussion

Vehicles

Nomadic user

Smart mobile phoneInvisible computing

Wearable computing

Intelligent house or office

Meeting room/conferenceTaxi/Police/Fire squad fleet

Service worker

Lonely wolf

Disaster relief and Disaster alarm Games

Military / Security

Anything missing?

What do you like?


Mobile Computing




Mobile devices

performanceperformance

Pager• receive only• tiny displays• simple text

messages

Mobile phones• voice, data• simple graphical displays

PDA• simpler graphical displays• character recognition• simplified WWW

Palmtop• tiny keyboard• simple versions

of standard applications

Laptop• fully functional• standard applications

Sensors,embeddedcontrollers



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

Higher loss-rates due to interference! emissions of, e.g., engines, lightening

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., 9.6kbit/s with GSM

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

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)


Mobile Computing




History of wireless communication I

1895 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

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 roaming1983 Start of the American AMPS (Advanced Mobile Phone

System, analog) 1984 CT-1 standard (Europe) for cordless telephones



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 170 countries! services: data with 9.6kbit/s, FAX, voice, ...



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


Mobile Computing




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 (approx. 50 B$ payed in Germany for 6

UMTS licences!)

2001 Start of 3G systems! Cdma2000 in Korea, UMTS in Europe, Foma (almost UMTS) in Japan



Wireless systems: overview of the development

cellular phones satellites wireless LANcordlessphones

1992:GSM

1994:DCS 1800

2001:IMT-2000

1987:CT1+

1982:Inmarsat-A

1992:Inmarsat-BInmarsat-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

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



The success story of Mobile “Computing”

Mobile Phones! Switzerland February 2002: More mobile phones than fixnet phones

! Worldwide: More mobile phones than Internet connections! SMS: “More net profit with SMS than with voice”

Laptops

! Switzerland 2001: For the first year less computers sold, but more mobile computers; private households buy 18% more laptops than the previous year.

0

100

200

300

400

500

600

700

800

1996 1997 `998 `999 2000 2001

DesktopMobile

[R.W

eiss

]


Mobile Computing




Mobile phones worldwide

[crt

.dk]



Mobile phones Top 12

[crt

.dk]



Mobile phones saturation

[crt.dk]



Internet vs. Mobile phones

[crt.dk]


Mobile Computing




Simple reference model

Application

Transport

Network

Data Link

Physical

Medium

Data Link

Physical

Application

Transport

Network

Data Link

Physical

Data Link

Physical

Network Network

Radio

[Tan

enb

aum

/Sch

iller

]



Course overview: Networking Bottom – Up Approach

! 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



Course Overview: Acronyms

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BluetoothSatellites

Optimal Frequency Allocation

Course overview: A large spectrum

TheorySystems

How can we access a shared

channel?

WAP How does my wireless LAN card work?

How do I route in a mobile ad-hoc network?

Orthogonal codes

GSM

WML and WMLscript


Mobile Computing




Course overview: Hands-On Exercises

We build a wireless LAN based ad-hoc network! We start with the “hello world” equivalent! Neighbor detection! Chat application! Multihop routing

! Multihop project! Emulator software! Grading!

Supported by ! paper exercises



Course overview: Lectures and Exercises??

Clustering

Mobile IP and TCP

Mobile Web

GSM

Topology Control

Geometric Routing

Ad-Hoc & Sensor Networks

Wireless LAN

Media Access Control

Physical and Link Layer

Introduction

Multihop Project 2

Instant Messenger

Multihop Project 3

Multihop Project 1

Theory: Ad-Hoc Networks

Multihop Routing 2

Multihop Routing 1

Topology Detection

Neighbor Detection

Theory: Codes/MAC

"Hello World"

Hard- and Software Tests



References and Literature

Jochen Schiller – Mobile Communications

Agrawal & Zeng – Wireless and Mobile SystemsIvan Stojmeniovic – Handbook of Wireless Networks and Mobile

Computing

Andrew Tanenbaum – Computer Networks, plus other booksJames D. Solomon – Mobile IP, the Internet unplugged

Charles E. Perkins – Ad-hoc networking

Pitoura & Samaras – Data Management for Mobile Computing

Tan & Ooi – Data Dissemination in Wireless Computing Environments

Plus tons of other books on specialized topics

Papers, papers, papers, …



Famous last words

“Mobile wireless computers are like mobile pipeless bathrooms –

portapotties. They will be common on vehicles, and at construction sites, and rock concerts. My advice is to wire up

your home and stay there.”

Bob Metcalfe, 1995(Ethernet inventor)


Mobile Computing




Overlay Networks - the global goal

regional

metropolitan area

campus-based

in-house

verticalhandover

horizontalhandover

integration of heterogeneous fixed andmobile networks with varyingtransmission characteristics

Mobile Computing Computer Science · 2/4/2009 · Thanks to Jochen Schiller and Roger Wattenhofer...

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Transcript of Mobile Computing Computer Science · 2/4/2009 · Thanks to Jochen Schiller and Roger Wattenhofer...