Context-AwareComputing

CSE494/598 Mobile Health and Social Networking

Context awareness:the essence of adaptability Context awareness

Resource awareness Adapt to available resources (connectivity, nearby devices

Situation awareness Adapt to the situation (mode, location, time, event)

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 accordingly Or risk being disruptive and annoying

Defining Context

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, year…)

Context history can also be useful

Another definition [Abowd & Mynatt]: Social context: user identity and

human partner identities

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)

• 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”

Context (cont’d) 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

social

temporal

motivational

location

user

Sensor data

computing

Low-levelcontext

Context processing

high-levelcontext

Context-aware application

activecontext

passivecontext

Context-Aware Application Design

How to take advantage of this context information? Schilit’s classification of CA applications:

1. Proximate selection:1. closely related objects & actions are emphasized/made easier to choose

2. Automatic contextual reconfiguration: adding/removing components or changing relationships between components based on context1. Switch to a different operation mode

2. Enable or disable functionality

3. Context-triggered actions: rules to specify how the system should adapt

3. Contextual information and commands: produce different results according to the context in which they are issued1. Narrow-down the output to the user using the context

2. 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 incomplete)

Map data Data Repository:

Points of Interest data e.g. pubs, restaurants, cinemas

Business Directory (doctors, plumbers etc by location)

Location-based Inventory

Issues Content providers – Telcos

jealously guarding own domain

Proprietary software e.g. Windows Live

Price of map data varies widely, very expensive in some countries e.g. Australia

Integration into customer’s web sites (API’s)

Cognitive Routing – routing / directions using terminology relevant to user (e.g. resident c/f tourist)

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 geocoding. 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 Networking:BuddyFinder App Mobile social networking meets

location based services 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 GPS+map service Extension of LBS+Navigation?

In-class excercise

Group up by table Name a smartphone app (existing or

imaginary) and identify its adaptability and context awarenessHandling 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• Neighbor’s

mood

SitutationMood

Current time, meeting time

Adaptivity • Center/zoon to your location

Pre-authorized access

Matching hitch-hikers to drivers

Order listPlaylist

Adjust music and volume

Notify of delays

Wireless Communicationsand Networks

Wireless Networks

FIXED NETWORK

PDA

FIXEDHOSTBASE

STATION

BASESTATION

BASESTATION

Mbps to Gbps

MOBILE HOST

WIRELESS LAN CELL2Kbps - 15Mbps

WIRELESS RADIO CELL9Kbps - 14Kbps

BASESTATION

PDA

10 kbps 100 kbps 1Mbps 10Mbps 100Mbps

1 m

10 m

100 m

1 km

10 km

100 km

WPAN(ZigBee,

Bluetooth)

2G 3G

WLAN(WiFi)

WMAN(WiMAX)

Satellite

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 (<0.1%); 4.4 million in 1990 (2.1%);13 million in 1994; 120 million in 2000; 187.6 million by 2004 (Cahner In-State Group Report).

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)

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 (<70MBps), metropolitan coverage (1 to 30 miles)

Packet Data Networks ARDIS 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 expensive

Network support by Android android.net

Classes that help with network access, beyond the normal java.net.* 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.

Uri:Immutable URI reference.

android.net.wifi 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 configuration.

WifiConfiguration.Protocol: Recognized security protocols.

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 javax.net java.net 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 MHzVery little storage – a few hundred kilobitsShort communication range – consumes a lot

of powerSmall 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

Retinal Implant Cortical Implant

Sensor-Based Visual Prostheses

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

• Project @ 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. Vision

* Sanskrit for long life

• To provide a realistic environment (test-bed) for testing communication protocols and systems for medical applications. 

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

EnvironmentalSensors (Temperature etc)

Medical Sensors(EKG, BP) controlledBy Mica2 motes

Body Based Intelligence

Home/Ward Based Intelligence

External Gateway

Central Server

Medical Facility Based Intelligence

MedicalProfessional

InternetStargateGateway

Ayushman: Current Setup

Internet

EnvironmentalData (accelerometer,Temperature, humidity,Light)

Blood Pressure

Oximeter

ZigBee802.11

Remote Clients

Central Server

BaseStation

Body Area Network

RS232

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

database

Bluetooth

Enabling Technologies

Mica2 TelosB

Imote2Mica2Dot

Iris

MicaZ

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 phoneMonitoring and

Control Software

Context GenerationPhysiological

(EKG, Perspiration, Heart Rate)

Environmental(Humidity, Temp)

Spatial(Home, Gym, Office,

Hospital, Park)

Temporal(Morning, Evening,

Night)

Sensor Network

Knowledge Context

Processor

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 patient’s

health.• A contextual template can be created for

specific physiological events for future reference.

Challenges• How to determine the

aggregate medical context from the four base contexts?

• How to create a contextual template for a patient?

AggregateContext

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 patient’s privacy is a legal requirement (HIPAA)

Excruciating Factors Wireless connectivity is always on

No clear understanding of: Trusted parties Security policies for medical environment

Devices are heterogeneous with limited capabilities

Traditional schemes too expensive for long term usage

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 (HIPAA) Passed in 1995 Provides necessary privacy protection

for health data 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

identity. Authorization – Ensure permissions granted for

actions performed by entity.

Energy EfficiencyNeed Sensors have very small

battery source. Sensors need to be active for

long time durations. 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.

Solutions

Solar Energy Better Battery

Vibration Body Thermal Power

Challenges and Solution Approaches

Constrained resources: power

Current technologyBattery-powered devices1150 mAh (G1), 1400 mAh (iPhone), 1300

mAh (Blackberry) 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 resources:data consistency Direct effect of connectivity challenge Approaches:

Disallow offline writes, use online-only mode (NFS)

System may become unresponsive during disconnections

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 resources:storage Current technologies

iPhone 3G: Flash 16GBG1: MicroSD (up to 16GB)

Future technologySolid state hard drives

Approaches:Stored data compression, selective data,

remote storage

Constrained resources:user interface methods Current technologies

Display size: ~5ʺ 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, templates)

Groups

Groups 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