Survey of Context Aware Systems(for Winter Camo)[1]

8/8/2019 Survey of Context Aware Systems(for Winter Camo)[1]

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Dept. of Computer & Information Science, Korea UniversityDept. of Computer & Information Science, Korea University

Part I

Surveys of Context-aware Systems

2008.01.28

http://idb.korea.ac.kr

DB & Mining Lab.

Korea University


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DB & MINING Lab., Dept. of Computer & Information ScienceDB & MINING Lab., Dept. of Computer & Information Science2

Contents

Definition of Context & Context-aware Application

Architecture of Context-aware System

Context Models

Existent Context-aware Applications

- Office and Meeting Tools

- Tourist Guide

- Memory Aids

- Context-aware Home

Essential Technologies for Context-aware Services


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Definition of Context

Context is

- situational information

- any information that can be used to characterize the

situation of an entity. An entity is a person, place, or object

that is considered relevant to the interaction between a user

and an application, including the user and application

themselves.

- the set of environmental states and settings that eitherdetermines an applications behavior or in which an

application event occurs


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Categories of Context(1)

Categories of Context

- Primary context :

Location (where)

Identity (who)

Time (when)

Activity (what)

- Secondary context

can be indexed by primary context

Ex) given a persons identity,

phone number, addresses, birthdate

given an entitys location,

what object are near, what activity is occurring near the

entity


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Categories of Context(2)

Another categories of Context

- external (physical) context :

can be measured by h/w sensors

location, light, sound, movement, touch, temperature

- internal (logical) context:

be specified by users or captured monitoring the usersinteraction

users goal, tasks, users emotional state


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Context-aware Application

Definition of Context-Aware

- A system is context-aware if it uses context to provide relevant

information and/or services to the user, where relevancy

depends on the users task

Characteristics of Context-Aware application

- presentation of information and services to a user

- automatic execution of a service

- taggingof context to information for later retrieval


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DB & MINING Lab., Dept. of Computer & Information ScienceDB & MINING Lab., Dept. of Computer & Information Science

Architecture of Context-aware Systems

Different approaches context-aware systems

- Direct sensor access:

the client s/w gathers the desired information directly form these

sensor without layer for gaining and processing sensor data

drivers for the sensor are hardwired into the application

law extensibility, impossibility of managing multiple concurrentsensor access

- Middleware based:

a layered architecture with the intention of hiding low-level

sensing details

high extensibility

- ContextServer

middleware base architecture + distributed approach

gathering sensor data context server


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Abstract Architecture(1)

application

storage/management

preprocessing

raw data retrieval

sensor

Sensor

- sensing hardware + every data source which provide

usable context information

Virtual sensors : sourcing context data from s/w

Logical sensors : combining physical sensor + virtual sensor

-Categories of Sensor

Physical sensors


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application

storage/management

preprocessing

raw data retrieval

sensor

raw data retrieval- raw data retrieval by using

appropriate drivers for physical

sensor and APIs for virtual and

logical sensors

preprocessing

- reasoning and interpreting (transforming)

- aggregating of raw context data- solving of sensing conflicts


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application

storage/management

preprocessing

raw data retrieval

sensor

storage/management- storing context history

application

- implementing actual reaction on different events and

context-instances


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Existent Context-aware Applications

Categories of Context-aware Applications

- Office and Meeting Tools

- Tourist Guide

- Memory Aids

- Context-aware Home


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Office and Meeting Tools(1)

The Active Badge System(1992)

- Group: Olivetti Research Ltd.

- the first context-aware applications.

- persons with badges that transmitted IR-signal

- after sensing a location of a person, forwarding calls to

the closest phone


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Office and Meeting Tools(2)

The ParcTab System

- Group: Xerox Palo Alto Research Center

- ParcTab: small wireless palm-sized computer

- presenting information about the room the user was in

- helping the user find the most convenient local resource,

e.g. the nearest printer- Locating other person with ParcTab Displaying the

location information on Active map

ParcTab terminal


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Office and Meeting Tools

Gaia

- Group : Dept. of CS, University of Illinois

- extending typical operating system concepts to include

context, location awareness, mobile computing devices

and actuators like door locks and light switches


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Tourist Guides

GUIDE

- Group: Lancaster University(96~99)

- terminal: Fujitsu Teampad 7600 portable PC

- supporting Lancaster city visitor

- screenshot of GUIDE


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Memory Aids(1)

Forget-Me-Not

- Group: Rank Xerox Research Center

- PDA system that records where its user is, who they are

with, whom they phone, and other autobiographical

information and store it in a DB for later query

- terminal: ParcTab


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Memory Aids(2)

StartleCam

- Group: MIT Media Lab.

- wearable computer (with digital camera, digital modem)

+ skin conductivity sensor


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Context-aware Homes(1)

EasyLiving

- Group: Vision Group at Microsoft Research

- computer vision for person-tracking and visual user

interaction.

- multiple sensor modalities combined.

- use of a geometric model of the world to provide context.

- automatic or semi-automatic sensor calibration and

model building.

- fine-grained events and adaptation of the user interface.

- device-independent communication and data protocols.


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(1)

1. (context sensing)

2. (context change sensing)

3. (context modeling)

4. (context fusion & reasoning)

5. (context exchange)

6. (context toolkit)

7. (context-aware

service description language)

8. (context-aware service

infrastructure)


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(2)

1.

- : ,,

- q q q(GPS)

q

,q

,,,

Ad hocq

q h/w

qq


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(3)

2.

- polling reporting

3.

4.

N

5.

application

6.


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(4)

7.

- WSDL-

8.

,,,q infrastructure


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Part II

Context-Aware Artifacts:

TwoDevelopment Approaches

http://idb.korea.ac.kr

DB & Mining Lab.

Korea University


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Introduction

Two development approaches for CA

- Self-supported context awareness

designers build the ability to perceive context, reason with it, and

act accordingly into the device or its dedicated hardware support.

- nfrastructure-supported context awareness

designers obtain context aware capabilities by harnessing a

hardware and software infrastructure external to and associated

with the devices space.


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Context-aware mobile phones (1)

SenSay

- context-aware mobile phone that modifies its behavior

based on its user's state and surroundings

- uses a combination of sensors, including a voice microphone,

an ambient-noise microphone, accelerometers, and a lightsensor.


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- uses a finite-state machine to track the phones internal

states (uninterruptible, high activity, normal, and idle)

- automatically controls ringer and vibration levels, send

short-message-service messages to callers, suggest calls to

make

- provides access to the users electronic calendar- Architecture of Sensay



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TEA-II (Technology for Enabling Awareness)

- self-contained hardware device that plugs into mobile

phones to add context-aware capabilities

- The plug-ins sensors: two light sensor, two microphones, a

dual axis accelerometer, a digital temperature sensor and a

touch sensor.

- detects phone situations( in hand, on table, in pocket, and

outdoors)

- explores an exchange of context information between caller

and callee.- adds a delay of up to 30 seconds.

- Doesnt consider internal phone state and action decision

making



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Sensor-Doll

- emits different sounds and music according to its situation

and how users handle it

Spoons and cups- Mediacup

- MITs Chameleon Mug

- MITs Intelligent Spoon

Other context-aware objects (1)


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Funiture

- Chameleon Table

- Smart Couch

Medication dispensers

- Context-aware pill bottle



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Cameras

- Context photography:

uses sound and movement as context information and a set of

custom-made computer graphics effects which affect images in real

time

Example of context pictures



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Discussion

Advantages of self-supported CA

- By equipping objects with sensors, we can gain otherwise

unavailable information about the objects situation

- Reduced dependency on external infrastructure

Challenges of self-supported CA

- embedding sensors unobtrusively

- reasoning with the context efficiently and accurately given

limited computational resources

- enabling appropriate actions


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Infrastructure-supported CA (1)

Infrastructure for CA- acts as a mechanism for detecting, combining, and reasoning with

different objects disparate context information

- should not only consist of an architecture to represent objects and

events, but also provide various services

- a well-established, pervasive, reliable, and publicly accessible set of

technologies that act as a foundation for other systems

The relationship between CA

artifacts and the context-awareness

infrastructure


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Weather-aware clothes hanger

- hangers light up according to the days forecast

RFID Chef prototype

- Detects RFID-tagged grocery items on a kitchen counter

- Display a list of recipes using these items as ingredients


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Benefits of infrastructure support

- hardware, platform, and language independence

- ease of maintenance, in that administrators can change

infrastructure-linked services, sensors, and artifacts while

the system is running

- improved context awareness economics

- Users can update infrastructures and add new artifacts

to an existing environment

- can support complex context-awareness behavior


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Conclusion

Considerations for CA Developers

- How can a system best acquire context?

- Should we choose a self-supported or infrastructure-

based approach (or some combination)?

- How can the system reason with and use context for a

particular application given the constraints of cost,reasoning efficiency, timeliness of action, and user

intelligibility?

- How can we program such entities to respond

appropriately to richer contextual information?- How will users perceive automatic responses from

artifacts and devices?

Survey of Context Aware Systems(for Winter Camo)[1]

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