pervasive and mobile computing - csit.uob.edu.pk

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Dr. Atiq Ahmed

PervasiveComputingPervasive Computing

Wireless andMobileComputingIntroduction

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Pervasive and Mobile Computing

Dr. Atiq [email protected]

Department of Computer Science & Information TechnologyUniversity of Balochistan

Lecture 04

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Outline

1 Pervasive ComputingPervasive Computing

2 Wireless and Mobile ComputingIntroductionWiNet Types

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Related FieldsMobile Computing

Solutions from MOBIMany basic principles of DIST design continued to apply toMOBI

BUT

Four key constraints of mobility required specializedtechniques for MOBI

Unpredictable variation in network qualityLowered trust and robustness of mobile elementsLimitations on local resources imposed by weight and sizeconstraintsConcern for battery power consumption

Mobile computing - still a very active and evolving field ofresearch

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Related FieldsSpecific subarea solutions for MOBI

Mobile NetworkingIncl. mobile IP, ad hoc protocols, techniques for improving TCPperformance in wireless networks

Mobile Information AccessIncl. disconnected operation, bandwidth-adaptive file access,selective control of data consistency

Support for Adaptive ApplicationsIncl. transcoding by proxies, adaptive resource management

System-level Energy Saving TechniquesIncl. energy-aware adaptation, variable-speed processorscheduling, energy-sensitive (=adaptive) memorymanagement

Location SensitivityIncl. location sensing, location-aware (=adaptive) systembehavior

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Related FieldsMobile Computing Issues

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Pervasive Computing

RECALL

PERV environment - one saturated with computing &communication capability, yet so gracefully integrated withusers that it becomes a “ technology that disappears”

Since motion is an integral part of everyday life, PERV mustsupport mobility

Otherwise, a user will be acutely aware of the technology by itsabsence when he/she moves

Hence, research in pervasive computing subsumes that ofMOBI

BUTResearch in PERV goes much further

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Pervasive Computing

PERV includes four additional research thrusts

Effective Use of Smart SpacesInvisibilityLocalized ScalabilityMasking Uneven Conditioning

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Pervasive ComputingPervasive Computing Issues

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Pervasive ComputingPervasive Computing Research Lines

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Pervasive ComputingEffective Use of Smart Spaces

A space

An enclosed area E.g., a meeting room or corridor

OR

A well-defined open area E.g., a courtyard or a city square

Smart space = space with embedded computinginfrastructure

E.g., smart space within buildings created by embeddingcomputing infrastructure within building infrastructure

Smart space brings together two worlds disjoint until now

Physical space (physical world)Cyberspace

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Pervasive ComputingEffective Use of Smart Spaces

The fusion of physical world (PHYS) and cyber-world (CYB)enables sensing and control of one world by the other

Example of sensing and control of PHYS by CYB Automaticadjustment of heating, cooling and lighting levels in a roombased on an occupant’s electronic profile (incl. presencepatterns)Example of sensing and control of CYB by PHYS Softwareon a user’s computer may behave differently depending onwhere the user is currently located

Note

Smartness may extend to individual objects, whether located in asmart space or not

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Pervasive ComputingInvisibility

Complete disappearance of pervasive computing technologyfrom a user’s consciousness = invisible computing [Weiser]

A reasonable approximation: minimal user distraction

BUT

Getting too close to the ideal might not be perfect: A (small)degree of visibility might be needed

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Pervasive ComputingLocalized Scalability

Basic model of pervasive computing interactions

User’s personal computing space (UPCS)User’s surroundings (US)Interactions between UPCS & US

Scalability problems in pervasive computingThe smarter is the space, the larger is interaction intensity

This has severe bandwidth, energy and distraction implicationsfor a wireless mobile user

The more users in the smart space the more interactions

Previous work typically ignored physical distance but PERVmust consider that

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Pervasive ComputingMasking Uneven Conditioning

“Smartness” of different spaces varies significantly

Well-equipped conference room, office, or classroom smarterthan other locationsSpace smartness depends on

Technical factors: How well the space is saturated with smartdevicesNon-technical factors: Organizational structure, economics andbusiness models, . . .

Uniform “smartness” of spaces is years or decades away (ifever achieved)

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Few words about history . . .

1896: Guglielmo MarconiFirst demonstration of wireless telegraphyBased on long wave, requiring very large transmitters

1907: Commercial Trans-Atlantic Wireless ServiceHuge ground stations: 30 x 100m antenna masts

1920: Discovery of short waves by MarconiCheaper, smaller, better quality transmitters by vacuum tube

1982: Start of GSM in Europe (1G analog)

1983: Start of AMPS in America (1G analog)

1992: Start of GSM (2G digital)

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Few words about history . . .

1997: Wireless LAN - IEEE802.11

1998: Iridium satellite system66 satellites

1999: Standardization of additional WLANsIEEE standard 802.11bBluetoothWAP (Wireless Application Protocol): access to many servicesvia the mobile phone

2000: GSM with higher data rates (2.5G digital)HSCSD offers up to 57.6kbit/sFirst GPRS trials with up to 50 kbit/s

2001: Start of 3G systemsIMT - 2000, several members of a family, CDMA2000 in Korea,UMTS tests in Europe

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Fantastic Breakthrough Technology

Wireless communication networks

multiple networks “covering” the globeworld-wide deregulation and spectrum auctionsstandard communication systems and air link interfaces

Portable information appliances

laptops, notebooks, sub-notebooks, and MNCshand-held computersPDAs and Smartphones

Internet

TCP/IP & de-facto application protocolsubiquitous web content

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New Forms of Computing

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Mobile Computing

Using:

small size portable computers, hand-helds, MNC, and othersmall wearable devices,

To run stand-alone applications (or access remoteapplications) via:

wireless networks: IR, BlueTooth, WiLANs, Cellular, W-PacketData networks, SAT. etc.

By:

nomadic and mobile users (animals, agents, trains, cars, cellphones,. . . .)

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Nomadic, Mobile & Ubiquitous

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Mark Weiser’s views

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Impressive Wireless Infrastructure!

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Wireless Network Convergence2G/3G Mobility-Bandwidth Trade-off

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Wireless Network Overlay

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Wireless LAN

IEEE 802.11 standard: a family of specifications for WLANtechnology accepted in 1997

802.11 specifies an over-the-air interface between a Wi-clientand a base station or between two Wi-clients

802.11: up to 2 Mbps in the 2.4 GHz band802.11b: up to 11 Mbps in the 2.4 GHz band802.11a/g: up to 54 Mbps in the 5/2.4 GHz band802.11n: up to 220+ Mbps in the 2.4/5 GHz band (twoproposals not approved yet). Vendors already selling802.11pre-n devices

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Wireless LANWiLAN Security

WEP: Wired Equivalent Privacy

A basic wireless LAN security mechanism which is easy to setup & commonly usedDon’t rely on WEP for Wi-security due to number of flaws in itMany wireless home networks don’t even use WEP, whichmakes bad situation worseMAC address based access control mechanism doesn’t work

Use other security mechanisms such as

VPN (Virtual Private Network)PEAP (Protected Extensible Authentication Protocol)TTLS (Tunneled Transport Layer Security)

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Wireless Ad Hoc Networks

Wireless Ad Hoc Network (peer to peer)

A collection of autonomous nodes that communicate with eachother by forming a multi-hop radio network in a decentralizedmannerNo infrastructure, no default router available“every” node needs to be a router

Mobile Ad Hoc Networks (MANET)

Host movement frequentTopology change frequent

Wireless Ad Hoc Sensor Networks

A number of sensors spread across a geographical areaLimited resources on sensors

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Bluetooth

Used to connect and exchange information between deviceslike PDAs, mobile phones, laptops, PCs, printers & digitalcameras

Named after a Denmark king Harold Bluetooth, who is knownfor his unification of previously warring tribes

Low-cost, short range (up to 10m), low power consumption,license-free 2.45 GHz band

Using the same frequency range, Bluetooth differs from Wi-Fiin that

Different multiplexing schemesWi-Fi with higher throughput, greater distances, moreexpensive hardware, and higher power consumption

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Bluetooth

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RFID

Method of remotely storing and retrieving data using devicescalled RFID tags

Tag is a small object that can be attached to or incorporatedinto a productTags contain antennas to receive and respond to RF queriesfrom an RFID transceiverNo line-of sightWithstand difficult environmental conditions (cold, frost etc.)

Categories

Active TagsSemi-passivePassive

Applications

SCM, Automated toll collection, . . .

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RFID

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