CS441 â€“ Mobile & Wireless Computing Wireless Network Challenges

Mobile & Wireless Computing 1© Kemal Akkaya

Department of Computer ScienceSouthern Illinois University Carbondale

CS441 – Mobile & Wireless Computing

Wireless Network ChallengesDr. Kemal AkkayaE-mail: [email protected]


InstructorDr. Kemal Akkaya, [email protected], Faner 2138Office hours

Monday, Wednesday 1-2pm, Friday 9-9:50am.E-mail is the best way to communicate with me

Class Web Sitehttp://www.cs.siu.edu/~cs441

Teaching assistantMr. Ismail [email protected] hours

T:1:30-3:30pm orBy Appointment

Class Administration: Personnel

mailto:[email protected]


Class AdministrationNo Textbooks

I will provide slides for each chapterThere can be some papers for readingCheck the web site frequently

A reference book“Ad Hoc Wireless Networks, by Murthy and Manoj, 1st Ed., Prentice Hall, 2004. We’ll cover a few chapters from this book

Networking BackgroundNice to have a networking and operating systems background but not mandatory

Rose’s NetworkingTanenbaum’s Networking

We’ll briefly cover them in the class


What You Need to DoYour prerequisites

Basic concepts of operating systems and networksHighly motivated, critical, dedicated

Your workloadHomework assignments

Reading and summary of some papers/textbook chaptersExplanation for some questions/topics etc.

Hands-on Labs3-4 labs with Sensor motes

Two examsMidterm Final -Comprehensive

Class project (in a small group of around 3 people)Pick a simple protocolExplain and summarize how it worksImplement it in C, C++

Report and presentation on a topic you chooseWe will suggest topics, provide resourcesTopics will be chosen among hot areas in pervasive computing


Grading Policy and Class SurveyGrading

Please take the class survey

Help me to determine your background

Help me to determine the depth and topics

Suggest topics that you want to be covered

Group project 25%

Midterm Exam 15%

Quizzes 5%

Hands-on Labs 10%

Assignments 10%

Final Exam 20%

Presentation 15%


Mobile and Wireless Data NetworksExperiencing a tremendous growth over the last decade

Wide deployment of access infrastructureIn-door, out-door, MAN, WAN

Growth of Wireless DataMiniaturization of computing machinery : laptop PDA embedded sensorsIncreasing mobile work forceLuxury of tether less computingInformation on demand anywhere/anyplace

Some Facts:In 2005, more than 1/3rd of internet users had internet connectivity through a wireless enabled device (750 million users)!!! (Source: Intermarket group)In the year 2004 revenue from wireless data was $34B, and by the year 2010 the number of wireless data subscribers will hit 1B!!

What is Mobile and Wireless Computing?Distributed systems with portable computers and wireless communicationsUser can access data anytime, anywhere


BuzzwordsMobile Computing

Distributed systems with mobile usersIn-door/Out-doorVehicle/human speed

Nomadic ComputingSimilar to Mobile computing

Focuses more on in-door communications

Pervasive Computing : Ubiquitous ComputingMay add some user interface integrationSome says : AI + Mobile Computing stuff

Applications:Military

Border control, target tracking, intrusion detection etc.Civil

Habitat monitoring, search and rescue, meeting rooms etc.


Wireless Network TypesSatellite networks

Iridium (66 satellites)Qualcomm’s Globalstar (48 satellites)

Wireless WANs/MANsCDPD (Cellular Digital Packet Data )GPRS (General Packet Radio Service)

Wireless LANsIEEE 802.11 : SIU’s LAWN,

Wireless PANse.g. Infrared: Bluetooth

Ad-hoc networkse.g. Emergency relief, military

Sensor networkse.g. Environmental sensing-MICA motes

Wireless WAN Generations:1G (Past)

AMPS, TACS: No data 2G (Past/Present)

IS-136, GSM: <10Kbps circuit switched data

2.5G (Past/Present)GSM-GPRS, GPRS-136: <100Kbps packet switched

3G (Present/Immediate Future)

IMT-2000: <2Mbps packet switched

4G (Future)20-40 Mbps!!


Examples

PicoNet

Bluetooth

802.11 / WiFi

Wireless LAN


Applications: Home Networking

Courtesy Dr. Richard Yang, Yale


Applications: Outdoor Networking

ad ho

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

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

Courtesy Dr. Richard Yang, Yale


Application: Environmental Monitoring

Wireless Sensor Nodes

monitor an area of interest


Challenges of Wireless Computing1) Wireless Communication

Implications of using wireless communication for mobile computingThe differences between wireless and wired media

2) MobilityConsequences of mobility on mobile application and system design

3) Poor Resources due to PortabilityPressures that portability places in the design of mobile end-systems


1) Wireless CommunicationLimited Transmission Range

10m-500m Limited Bandwidth

Wireless networks deliver lower bandwidth than wired networks

1 Mbps Infrared communication11 Mbps wireless local radio communications (shared), IEEE 802.11b9.6 Kbps for wide-area wireless communication

Wired networks10-100 Mbps for Ethernet100 Mbps for FDDI155 Mbps for ATM1 Gbps for Gigabit Ethernet

DisconnectionsNetwork partitionsStall all applications

Uncertainty of PerformanceVariance of bit errorsVariance of delaysVariance of bandwidth

SecurityEasy to intrude in the wireless network

Heterogeneous devices and network connections

Wired links Same characteristics

Outdoor: RadioIndoor: InfraredRural Areas: Satellite


Heterogeneous Devices

PPerformanceerformance/Weight/Power Consumption/Weight/Power Consumption

Sensors,embeddedcontrollers

Mobile phones• voice, data• simple graphical displays• GSM

PDA• data• simpler graphical displays• 802.11

Laptop• fully functional• standard applications• battery; 802.11

Desktop• fully functional• standard applications• unlimited power supp• Gbps Ethernet

http://www.palminfocenter.com/ss.asp?f=sgh_i500_o_lg.jpg

http://www.amazon.com/exec/obidos/ASIN/B0000DALPW/ref=nosim/nowelectronic-20


2) MobilityAbility to change locations while connected to the network

A mobile computer can change its serverDNS server, print server, etc.

Dynamic EnvironmentNetwork Access Point Changes

Address changes: IP addressNetwork Performance Changes

Bandwidth, delay, error rate etc.Available resources change

Depends on the network it connected toData consistency changes

Writing/Reading to/from mobile databasesSecurity changes

Endpoint authentication harder


3) Poor ResourcesMobile devices are fundamentally different from stationary machines such as desktop computers

Must be designed with variety of constraints in mind, such as size and power consumption – properties much like a wristwatchThey should also be portable

Portability Constraints IncludeLow power consumption

You would not want to carry a battery that is bigger than your computer! Increased risk of data loss

Physical damageUnauthorized accessLoss and Theft

Small user-interfacesRequires a different windowing scheme Buttons versus Recognition

Limited on-board storage, memory, CPU etcPhysical restrictions, power constraints


SummaryWireless communication brings challenging network conditions

Slow and sometime disconnected communicationMobility causes greater dynamicisim of informationPortability results limited resources to be available on board Mobile computing designers should consider these issues in designing mobile systems, applications and networks that are comparable with the traditional stationary computing and communication in terms of operation, performance, and availabilityVery active research area in the last decade

Many interesting research problems

CS441 â€“ Mobile & Wireless Computing Wireless Network Challenges

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