Context-Aware Computing - PowerPoint PPT Presentation


PPT – Context-Aware Computing PowerPoint presentation | free to view - id: 7fd46-ZDc1Z


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Context-Aware Computing


How to determine the aggregate medical context from the four base contexts? ... Electronic health records store more and more sensitive information such as ... – PowerPoint PPT presentation

Number of Views:119
Avg rating:3.0/5.0
Slides: 43
Provided by: SCI76


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Context-Aware Computing

  • CSE494/598 Mobile Health and Social Networking

Context awarenessthe essence of adaptability
  • Context awareness
  • Resource awareness
  • Adapt to available resources (connectivity,
    nearby devices
  • Situation awareness
  • Adapt to the situation (mode, location, time,
  • Intention awareness (?)
  • Adapt to what the user wants to do
  • Context awareness is found in humans
  • We always adapt our behavior and actions
    according to the context (i.e. situation)
  • Pervasive computing devices that ubiquitously
    accompany humans (such as smartphones) must adapt
  • Or risk being disruptive and annoying

Defining Context
  • Dictionary definition
  • the interrelated conditions in which something
    exists or occurs
  • Definition for pervasive computing
  • any parameters that the application needs to
    perform a task without being explicitly given by
    the user
  • One definition Schilit
  • Computing context connectivity, communication
    cost, bandwidth, nearby resources (printers,
    displays, PCs)
  • User context user profile, location, nearby
    people, social situation, activity, mood
  • Physical context temperature, lighting, noise,
    traffic conditions
  • Temporal context (time of day, week, month,
  • Context history can also be useful
  • Another definition Abowd Mynatt
  • Social context user identity and human partner
  • Functional context what is being done, what
    needs to be done
  • Location context where it is happening
  • Temporal context when it is happening
  • Motivation context why it is happening (purpose)

Context (contd)
Sensor data
  • Other classifications of context
  • Low-level vs High-level context
  • Active vs Passive context
  • Putting it all together
  • Gather low-level context
  • Process and generate high-level context
  • Separate active from passive context
  • adjust

Context processing
Context-aware application
Context-Aware Application Design
  • How to take advantage of this context
  • Schilits classification of CA applications
  • Proximate selection
  • closely related objects actions are
    emphasized/made easier to choose
  • Automatic contextual reconfiguration
    adding/removing components or changing
    relationships between components based on context
  • Switch to a different operation mode
  • Enable or disable functionality
  • Context-triggered actions rules to specify how
    the system should adapt
  • Contextual information and commands produce
    different results according to the context in
    which they are issued
  • Narrow-down the output to the user using the
  • Broaden the output to the user using the context
  • Is this classification fundamental/inclusive?

Context-Aware functionality Examples
  • System optimization
  • power-save mode, silent mode etc
  • Connection optimization
  • Protocol selection, compression rate etc
  • Application Functionality
  • Presentation
  • Image orientation, locale etc

Location-Based Services
  • Requirements
  • Geocoder (convert street addresses to latitude /
    longitude), Reverse geocoder
  • Address Helper (many addresses inaccurate or
  • Map data
  • Data Repository
  • Points of Interest data e.g. pubs, restaurants,
  • Business Directory (doctors, plumbers etc by
  • Location-based Inventory
  • Issues
  • Content providers Telcos jealously guarding own
  • Proprietary software e.g. Windows Live
  • Price of map data varies widely, very expensive
    in some countries e.g. Australia
  • Integration into customers web sites (APIs)
  • Cognitive Routing routing / directions using
    terminology relevant to user (e.g. resident c/f

LBS Navigation
  • Basic form of Location-based services
  • Map service (Geocoder)
  • You are here service
  • Route discovery and generation of directions
  • Add-ons
  • Voice-activated
  • Adjust route to traffic and accident conditions
  • Integration with calendar and address book
  • Notify target partner of arrival
  • android.location
  • Classes defining Android location-based and
    related services.
  • Interfaces
  • LocationListener Used for receiving
    notifications from the LocationManager when the
    location has changed.
  • Classes
  • Address represents an Address, i.e, a set of
    Strings describing a location.
  • Geocoder handles geocoding and reverse
  • Location represents a geographic location sensed
    at a particular time (a "fix").
  • Criteria indicates the application criteria for
    selecting a location provider.
  • LocationManager provides access to the system
    location services.
  • LocationProvider An abstract superclass for
    location providers.

LBS Social NetworkingBuddyFinder App
  • Mobile social networking meets location based
  • Mobile friend tracking directory services
  • Proprietary internal messaging connectable to any
    messaging service
  • Friends become closer than ever because you know
    where they are
  • Location from GPSmap service
  • Extension of LBSNavigation?

In-class excercise
  • Group up by table
  • Name a smartphone app (existing or imaginary) and
    identify its adaptability and context awareness
  • Handling variable resources
  • Connection, battery
  • Handling variable context
  • Location, time

In-class exercise, feedback
Table 1 Table 2 Table 3 Table 4 Table 5 Table 6
Application Google maps Secure gateway Hitch-hikers Party Management Mood-based music player Meeting scheduler (calendar and email)
Context Your location Security gateway availability Location destination Location Partners Neighbors mood Situtation Mood Current time, meeting time
Adaptivity Center/zoon to your location Pre-authorized access Matching hitch-hikers to drivers Order list Playlist Adjust music and volume Notify of delays
Wireless Communicationsand Networks
Wireless Networks
Wireless Networks
  • Cellular - GSM (Europe), TDMA CDMA (US)
  • FM 1.2-9.6 Kbps Digital 9.6-14.4 Kbps
    (ISDN-like services)
  • Cellular Subscribers in the United States
  • 90,000 in 1984 (lt0.1) 4.4 million in 1990
    (2.1)13 million in 1994 120 million in 2000
    187.6 million by 2004 (Cahner In-State Group
  • Handheld computer market will grow to 1.77
    billion by 2002
  • Public Packet Radio - Proprietary
  • 19.2 Kbps (raw), 9.6 Kbps (effective)
  • Private and Share Mobile Radio
  • Paging Networks typically one-way communication
  • low receiving power consumption
  • Satellites wide-area coverage (GEOS, MEOS,
  • LEOS 2.4 Kbps (uplink), 4.8Kbps (downlink)

Wireless Networks (Cont.)
  • Wireless Local Area Networks
  • IEEE 802.11 Wireless LAN Standard based systems,
    e.g., Lucent WaveLan.
  • Radio or Infrared frequencies 1.2 Kbps-15 Mbps
  • Wireless Metropolitan Area Networks
  • IEEE 802.16 Worldwide Interoperability for
    Microwave Access (WiMAX)
  • Microwave frequencies (2.5-66GHz), broadband
    (lt70MBps), metropolitan coverage (1 to 30 miles)
  • Packet Data Networks
  • RAM
  • Cellular Digital Packet Data (CDPD)
  • Private Networks
  • Public safety, UPS.

Wireless Local Area Network
  • Data services IP packets
  • Coverage Area Offices, buildings, campuses
  • Roaming Within deployed systems
  • Internet access via LAN.
  • Type of services Data at near LAN speed.
  • Variant Connectivity
  • Low bandwidth and reliability
  • Frequent disconnections
  • predictable or sudden
  • Asymmetric Communication
  • Broadcast medium
  • Monetarily expensive
  • Charges per connection or per message/packet
  • Connectivity may be weak, intermittent and

Network support by Android
  • Classes that help with network access, beyond the
    normal APIs. more...
  • Classes
  • ConnectivityManager answers queries about the
    state of network connectivity.
  • DhcpInfo A simple object for retrieving the
    results of a DHCP request.
  • MailTo MailTo URL parses a mailto scheme URL and
    then can be queried for the parsed parameters.
  • NetworkInfo Describes the status of a network
    interface of a given type
  • Proxy A convenience class for accessing the user
    and default proxy settings.
  • UriImmutable URI reference.
  • Provides classes to manage Wi-Fi functionality on
    the device. more...
  • Classes
  • ScanResult Describes information about a
    detected access point.
  • WifiConfiguration A class representing a
    configured Wi-Fi network, including the security
  • WifiConfiguration.Protocol Recognized security
  • WifiConfiguration.Status Possible status of a
    network configuration.
  • WifiInfo Describes the state of any Wifi
    connection that is active or is in the process of
    being set up.
  • WifiManager This class provides the primary API
    for managing all aspects of Wi-Fi connectivity.
  • WifiManager.WifiLock Allows an application to
    keep the Wi-Fi radio awake.

Network support by Android
  • Other packages
  • org.apache.http
  • android.telephony.gsm
  • Provides APIs for utilizing GSM-specific
    telephony features, such as text/data/PDU SMS
    messages. more...
  • Classes
  • GsmCellLocation Represents the cell location on
    a GSM phone.
  • SmsManager Manages SMS operations such as
    sending data, text, and pdu SMS messages.
  • SmsMessage A Short Message Service message.

Wireless Sensor Networks
What is a Wireless Sensor Network?
  • Wireless Sensor Node Sensor Actuator ADC
    Microprocessor Powering Unit Communication
    Unit (RF Transceiver)
  • An ad hoc network of self-powered and
    self-configuring sensor nodes for collectively
    sensing environmental data and performing data
    aggregation and actuation functions reliably,
    efficiently, and accurately.

GPS Sensor Node
Limitations of Wireless Sensors
  • Wireless sensor nodes have many limitations
  • Modest processing power 8 MHz
  • Very little storage a few hundred kilobits
  • Short communication range consumes a lot of
  • Small form factor several mm3
  • Minimal energy constrains protocols
  • Batteries have a finite lifetime
  • Passive devices provide little energy

Some Sample Applications
  • Industrial and Commercial Uses
  • Inventory Tracking RFID
  • Automated Machinery Monitoring
  • Smart Home or Smart Office
  • Energy Conservation
  • Automated Lighting
  • Military Surveillance and Troop Support
  • Chemical or Biological Weapons Detection
  • Enemy Troop Tracking
  • Traffic Management and Monitoring

Sensor-Based Visual Prostheses
Retinal Implant
Cortical Implant
Typical Sensor Node Features
  • A sensor node has
  • Sensing Material
  • Physical Magnetic, Light, Sound
  • Chemical CO, Chemical Weapons
  • Biological Bacteria, Viruses, Proteins
  • Integrated Circuitry (VLSI)
  • A-to-D converter from sensor to circuitry
  • Packaging for environmental safety
  • Power Supply
  • Passive Solar, Vibration
  • Active Battery power, RF Inductance

Traffic Management Monitoring
  • Future cars could use wireless sensors to
  • Handle Accidents
  • Handle Thefts
  • Sensors embedded in the roads to
  • Monitor traffic flows
  • Provide real-time route updates

Ayushman A Pervasive Healthcare System
Sanskrit for long life
Environmental Sensors (Temperature etc)
  • Project _at_ IMPACT Lab, Arizona State University
  • To provide a dependable, non-intrusive, secure,
    real-time automated health monitoring.
  • Should be scalable and flexible enough to be used
    in diverse scenarios from home based monitoring
    to disaster relief, with minimal customization.

Stargate Gateway
External Gateway
Central Server
Medical Sensors (EKG, BP) controlled By Mica2
Medical Professional
Home/Ward Based Intelligence
Body Based Intelligence
Medical Facility Based Intelligence
  • To provide a realistic environment (test-bed) for
    testing communication
  • protocols and systems for medical

K. Venkatasubramanian, G. Deng, T. Mukherjee, J.
Quintero, V Annamalai and S. K. S.
Gupta, "Ayushman A Wireless Sensor Network Based
Health Monitoring Infrastructure and Testbed",
In Proc. of IEEE DCOSS June 2005
Ayushman Current Setup
Base Station
Central Server
Blood Pressure
Environmental Data (accelerometer, Temperature,
humidity, Light)
Body Area Network
  • Properties
  • Hardware and software based architecture
  • Multi-tiered organization
  • Real-time, continuous data collection
  • Query support (past, current data)
  • Remote monitoring capability through the Internet
  • Simple alarm generation

Remote Clients
Enabling Technologies

Commercially available sensor boards
Open source OS with support for ad hoc networking
Phone to WSN Interface
  • Design Principles
  • To minimize the changes to the existing WSN
    architecture (required to maintain backward
    compatibility with previous apps.)
  • To leverage COTS hardware and existing software
    solutions (to minimize the development time).
  • Issues to address
  • Phone to sensors interface
  • Data handling on the cell phone

Monitoring and Control Software
Context Generation
  • Medical Context
  • Is an aggregate of 4 base contexts.
  • Each physiological event has to be characterized
    by all 4 base contexts for accurate
    understanding of patients
  • health.
  • A contextual template can be created for
    specific physiological events for future

Physiological (EKG, Perspiration, Heart Rate)
Context Processor
Spatial (Home, Gym, Office, Hospital, Park)
Aggregate Context
Temporal (Morning, Evening, Night)
Sensor Network
  • Challenges
  • How to determine the aggregate medical context
    from the four base contexts?
  • How to create a contextual template for a

Environmental (Humidity, Temp)
Base Context
Security in Pervasive Healthcare
  • Context
  • Patient data is transmitted wirelessly by low
    capability sensors
  • Patient data is therefore easy to eavesdrop on
  • Security schemes utilized may not be strong
    enough for cryptanalysis
  • Patient data is stored in electronic format and
    is available through the Internet
  • Makes it easy to access from around the world and
    easy to copy
  • Data can be moved across administrative
    boundaries easily bypassing legal issues.
  • Electronic health records store more and more
    sensitive information such as psych reports and
    HIV status
  • Preserving patients privacy is a legal
    requirement (HIPAA)
  • Excruciating Factors
  • Wireless connectivity is always on
  • No clear understanding of

Security Related Issues
  • New Attacks
  • Fake emergency warnings.
  • Legitimate emergency warnings prevented from
    being reported in times.
  • Unnecessary communication by malicious entity
    with sensors can cause
  • Battery power depletion
  • Tissue heating
  • Technology
  • Efficient cryptographic primitives
  • Cheaper encryption, hash functions
  • Better sensor hardware design
  • Cheap, tamper-resistant sensor hardware
  • Better communication protocol design
  • Better techniques for controlling access to
    patient EHR
  • Legislation
  • Health Information Privacy and Accountability Act
  • Passed in 1995
  • Provides necessary privacy protection for health
  • Developed in response to public concern over
    abuse of privacy in health information
  • Establishes categories of health information
    which may be used or disclosed
  • Requirements
  • Integrity - Ensure that information is accurate,
    complete, and has not been altered in any way.
  • Confidentiality - Ensure that information is only
    disclosed to those who are authorized to see it.
  • Authentication Ensure correctness of claimed
  • Authorization Ensure permissions granted for
    actions performed by entity.

Energy Efficiency
  • Need
  • Sensors have very small battery source.
  • Sensors need to be active for long time
  • For implantable sensors, it is not possible to
    replace battery at short intervals.
  • Challenge
  • Battery power not increasing at same rate as
    processing power.
  • Small size (hence less energy) of the batteries
    in sensors.

Better Battery
Solar Energy
Body Thermal Power
Challenges and Solution Approaches
Constrained resources power
  • Current technology
  • Battery-powered devices
  • 1150 mAh (G1), 1400 mAh (iPhone), 1300 mAh
  • Future technology
  • Replenishable energy storage
  • Until then
  • Power-save modes wireless, screen etc.

Constrained resources connectivity
  • Current technologies
  • WiFi, WiMAX, Bluetooth, 3G
  • Possibly no coverage, intermittent interruptions,
    limited(?) bandwidth
  • Future technology
  • Still wireless, interchange between technologies,
    more availability bandwidth
  • Approaches
  • Disconnections use of local cache, buffering
  • Adaptive encoding and compression

Constrained resourcesdata consistency
  • Direct effect of connectivity challenge
  • Approaches
  • Disallow offline writes, use online-only mode
  • System may become unresponsive during
  • Distributed/Network file system (Coda, Andrew)
  • Requires heavy clients with large cache
  • May be too heavy for certain devices

Constrained resources computation
  • Current technologies
  • Blackberry 3G Intel PXA901 312 MHz, 64 MB flash
    16 MB SDRAM
  • iPhone 3G ARM 1176, 400/620 MHz 128 MB DRAM
  • G1 Qualcomm MSM7201A, 528MHz, 192 MB DDR SDRAM
    256 MB Flash
  • Future technology
  • Limited by wattage and available energy
  • Always behind desktop CPUs
  • Approaches
  • Lightweight, streamlined O/S and applications

Constrained resourcesstorage
  • Current technologies
  • iPhone 3G Flash 16GB
  • G1 MicroSD (up to 16GB)
  • Future technology
  • Solid state hard drives
  • Approaches
  • Stored data compression, selective data, remote

Constrained resourcesuser interface methods
  • Current technologies
  • Display size 5"
  • Constrained or no keyboard
  • Future technologies
  • There may be a convergence of input methods (e.g.
    touch screens, voice recognition)
  • presentation will continue to be different
    (audiovisual capabilities and sizes)
  • Solution approaches
  • Adjust content to match size of display (e.g.
    favor close-ups)
  • Use assistive methods (e.g. auto-completion,

  • Group1
  • Logsdon, Brandon
  • Boyd, Jeffrey Michael
  • Yao, Robert James Y (?)
  • Group 2
  • Olsen, Samuel H
  • Perambalam, Sivaguru
  • Viswanathan, Lakshmie Narayan
  • Group 3
  • Bootz, Bradley Justin
  • Douglas, Robert Wayne
  • Freed, Natalie Anne
  • Group 4
  • Krolikowski, Tomasz
  • Randolph, April A
  • Gutierrez, Pedro U
  • Group 5
  • Chulick, Ryan Owen
  • Hursh, Nathaniel P
  • Trujillo, Miguel Zeniff
  • Group 6
  • Deshpande, Koustubha Achyut
  • Neelakandan, Vikram
  • Abbasi, Zahra
  • Group 7
  • Banerjee, Ayan
  • Thangavel, Karthik