A Mobile Context-Aware Behavior Modification System for Healthy Lifestyle Management October 17, 2007 Taimur Hassan

Agenda Introduction Problem Statement Research Questions Background HMSS Details Evaluations Research Answers Contribution Future Goals Questions

Introduction

Problem Statement

Research Questions

Background

HMSS Details

Evaluations

Research Answers

Contribution

Future Goals

Questions

Introduction This dissertation emerged from collaboration with Kaiser Permanente’s preventive medicine division The division conducts classes that aim at educating participants about weight management through: Adopting a balanced diet in their daily life Counting calories Exercise Reducing visits to fast-food restaurants

This dissertation emerged from collaboration with Kaiser Permanente’s preventive medicine division

The division conducts classes that aim at educating participants about weight management through:

Adopting a balanced diet in their daily life

Counting calories

Exercise

Reducing visits to fast-food restaurants

Problem Statement Problems with the preventive medicine approach: Maintaining motivation outside classroom is difficult because of the environment participants often face Keeping track of activity and related parameters is tedious Proposed idea: A mobile system that sends motivational messages based on analyses of a participant’s activity and location data. It has been named the Health Management and Support System (HMSS)

Problems with the preventive medicine approach:

Maintaining motivation outside classroom is difficult because of the environment participants often face

Keeping track of activity and related parameters is tedious

Proposed idea: A mobile system that sends motivational messages based on analyses of a participant’s activity and location data. It has been named the Health Management and Support System (HMSS)

Research Questions Before such a system could be designed, questions to be answered included: How could activity and location information be captured? Can these sources be feasibly used for choosing feedback related to the health choices of a user? Could such feedback be effective in changing the behavior of a user?

Before such a system could be designed, questions to be answered included:

How could activity and location information be captured?

Can these sources be feasibly used for choosing feedback related to the health choices of a user?

Could such feedback be effective in changing the behavior of a user?

Background To understand how HMSS works, a brief introduction to pervasive and context-aware computing is needed Pervasive computing refers to an arrangement where information processing has been integrated into everyday objects that surround a user A common example given is a refrigerator that can sense what is placed inside and can warn the owner if something has expired or finished and put the item on an electronic shopping list

To understand how HMSS works, a brief introduction to pervasive and context-aware computing is needed

Pervasive computing refers to an arrangement where information processing has been integrated into everyday objects that surround a user

A common example given is a refrigerator that can sense what is placed inside and can warn the owner if something has expired or finished and put the item on an electronic shopping list

Background (cont.) What is Context? The set of facts or circumstances that surround a situation or event (Wordnet) Context-aware computing is a sub-discipline of pervasive computing Describes the idea of computer systems reacting to what is sensed in the user’s environment An example is a room’s light dimming when the system senses the subject wants to lie down Context can be sensed using information such as activity, location, time of day and schedule using a variety of sources Why is context so important for HMSS? Studies conducted suggest that contextualization of motivational messages reduces the chances of the message being ignored HMSS uses context to select the most appropriate message

What is Context?

The set of facts or circumstances that surround a situation or event (Wordnet)

Context-aware computing is a sub-discipline of pervasive computing

Describes the idea of computer systems reacting to what is sensed in the user’s environment

An example is a room’s light dimming when the system senses the subject wants to lie down

Context can be sensed using information such as activity, location, time of day and schedule using a variety of sources

Why is context so important for HMSS?

Studies conducted suggest that contextualization of motivational messages reduces the chances of the message being ignored

HMSS uses context to select the most appropriate message

Background (cont.) Some examples of context-aware applications: A context-aware remote control developed at MIT which combines behavior modification theory and daily activity records to persuade users to increase their physical activity and reduce television viewing Mitchell et al. describe an application which is wired with sensors to track users and allow them to summon each other without worrying about location SenSay phone developed by MIT can provide remote callers with the ability to communicate the urgency of their calls, make call suggestions to users when they are idle, and provide the caller with feedback on the current status of another SenSay user based on sensor data

Some examples of context-aware applications:

A context-aware remote control developed at MIT which combines behavior modification theory and daily activity records to persuade users to increase their physical activity and reduce television viewing

Mitchell et al. describe an application which is wired with sensors to track users and allow them to summon each other without worrying about location

SenSay phone developed by MIT can provide remote callers with the ability to communicate the urgency of their calls, make call suggestions to users when they are idle, and provide the caller with feedback on the current status of another SenSay user based on sensor data

HMSS Overview HMSS is based on knowledge from these main domains, as well as related fields such as mobile and sensor based computing It is a prototype that sends just-in-time motivational messages based on a user’s context Software packages include: .NET Windows Mobile SDK Java, Visual C#, PHP MySQL database Google Maps API GT2K gesture recognition library Hardware used: Windows Mobile Verizon XV6700 smartphone iTrek M5 Bluetooth GPS Receiver Sparkfun Bluetooth Accelerometers HMSS consists of two artifacts: A mobile client application A server

HMSS is based on knowledge from these main domains, as well as related fields such as mobile and sensor based computing

It is a prototype that sends just-in-time motivational messages based on a user’s context

Software packages include:

.NET Windows Mobile SDK

Java, Visual C#, PHP

MySQL database

Google Maps API

GT2K gesture recognition library

Hardware used:

Windows Mobile Verizon XV6700 smartphone

iTrek M5 Bluetooth GPS Receiver

Sparkfun Bluetooth Accelerometers

HMSS consists of two artifacts:

A mobile client application

A server

Mobile Client Application Connected to server via a subscribed data service Has two components: Sensor Manager Establishes connection with accelerometer and GPS receiver Responsible for upload, compression and transmission of raw data to server GUI Controls sessions Controls sensor data retrieval process Contains menus for setting session properties Feedback from the server is displayed in the GUI

Connected to server via a subscribed data service

Has two components:

Sensor Manager

Establishes connection with accelerometer and GPS receiver

Responsible for upload, compression and transmission of raw data to server

GUI

Controls sessions

Controls sensor data retrieval process

Contains menus for setting session properties

Feedback from the server is displayed in the GUI

Server Has four components: Session Manager Handles data storage and processing for a session Contains GT2k and other functions for handling raw data A database Stores data related to all aspects of HMSS Message Selector Selecting feedback based on context Message Handler Customizes feedback and responsible for dispatch to mobile client

Has four components:

Session Manager

Handles data storage and processing for a session

Contains GT2k and other functions for handling raw data

A database

Stores data related to all aspects of HMSS

Message Selector

Selecting feedback based on context

Message Handler

Customizes feedback and responsible for dispatch to mobile client

Data Architecture HMSS data architecture represents the steps taken from raw data to user context Adopted from previous work by Dey et al. and Gellersen Used for simplifying feedback selection All data sources expressed as sensor types

HMSS data architecture represents the steps taken from raw data to user context

Adopted from previous work by Dey et al. and Gellersen

Used for simplifying feedback selection

All data sources expressed as sensor types

Sensor Layer Virtual Sensor Source: User data (weight, gender, address etc) Location Sensor Source: A GPS receiver External Physical State Sensor Source: An accelerometer

Virtual Sensor

Source: User data (weight, gender, address etc)

Location Sensor

Source: A GPS receiver

External Physical State Sensor

Source: An accelerometer

Cue Layer Abstracts raw sensor data into cues, or abstractions Example can be the output of a light bulb which is expressed as a number from 0-255 into high, medium and low Five cues derived from source layer: Speed (outdoor walking pace) Closest building (closest building to user) Indoor/outdoor (is user inside the building) Activity, as determined by GT2k Calories burnt

Abstracts raw sensor data into cues, or abstractions

Example can be the output of a light bulb which is expressed as a number from 0-255 into high, medium and low

Five cues derived from source layer:

Speed (outdoor walking pace)

Closest building (closest building to user)

Indoor/outdoor (is user inside the building)

Activity, as determined by GT2k

Calories burnt

Context Layer Responsible for determining a users context by using cues to help minimize misidentification Algorithms convert multiple cues into context at this layer, which is then used for feedback selection Two contexts defined, with ability to add more

Responsible for determining a users context by using cues to help minimize misidentification

Algorithms convert multiple cues into context at this layer, which is then used for feedback selection

Two contexts defined, with ability to add more

Evaluation Developed using all domains as a reference Eight unescorted subjects participating in mobile field experiments The first evaluation was a pilot, followed by further development and seven subsequent evaluations Each evaluation held in three phases Pre-experiment training Experiment Post-experiment interview Subjects were associated with SISAT Three questions asked in all evaluations: What features you would like to see? Would you like to use such a device all day? Did you alter your behavior during the course based on feedback?

Developed using all domains as a reference

Eight unescorted subjects participating in mobile field experiments

The first evaluation was a pilot, followed by further development and seven subsequent evaluations

Each evaluation held in three phases

Pre-experiment training

Experiment

Post-experiment interview

Subjects were associated with SISAT

Three questions asked in all evaluations:

What features you would like to see?

Would you like to use such a device all day?

Did you alter your behavior during the course based on feedback?

Pilot Held in March 2007 Instructions between three campus buildings, ACB, Sprague library and Hagelbarger’s lounge Two activities were included for messages, walking and resting Aimed at gathering data on technical and usability issues Subject followed an instruction sheet, while carrying a smartphone, a GPS receiver, and wearing three accelerometers Subject was female, in her twenties Two sessions were held: In first session, application crashed and session was reset The second session proceeded normally Subject was able to indicate via the smartphone whether the messages received were accurate or not

Held in March 2007

Instructions between three campus buildings, ACB, Sprague library and Hagelbarger’s lounge

Two activities were included for messages, walking and resting

Aimed at gathering data on technical and usability issues

Subject followed an instruction sheet, while carrying a smartphone, a GPS receiver, and wearing three accelerometers

Subject was female, in her twenties

Two sessions were held:

In first session, application crashed and session was reset

The second session proceeded normally

Subject was able to indicate via the smartphone whether the messages received were accurate or not

Course Go downstairs and exit the building from the southern exit Once outside, walk towards the Sprague library Enter the library from the southern entrance and climb up the stairs to the fifth floor Sit on the chairs available on the fifth floor for 2-4 minutes Go downstairs and leave the building and proceed to Hagelbarger’s restaurant at CGU. Once inside the restaurant, sit inside for one Leave the restaurant through the southern exit, and walk to the ACB building Sit on a bench outside the northern entrance of ACB for 2-4 minutes Enter ACB from the northern entrance, go up the stairs and sit on the couch for 2 minutes

Go downstairs and exit the building from the southern exit

Once outside, walk towards the Sprague library

Enter the library from the southern entrance and climb up the stairs to the fifth floor

Sit on the chairs available on the fifth floor for 2-4 minutes

Go downstairs and leave the building and proceed to Hagelbarger’s restaurant at CGU.

Once inside the restaurant, sit inside for one

Leave the restaurant through the southern exit, and walk to the ACB building

Sit on a bench outside the northern entrance of ACB for 2-4 minutes

Enter ACB from the northern entrance, go up the stairs and sit on the couch for 2 minutes

Pilot Results Location did not update properly because the subject had put the GPS receiver in pant pocket Subject received six messages Subject found five of the messages inaccurate because of the GPS error Subject indicated surprise that stair climbing was not recognized Subject indicated less sensors were desirable Resulted in several updates to system

Location did not update properly because the subject had put the GPS receiver in pant pocket

Subject received six messages

Subject found five of the messages inaccurate because of the GPS error

Subject indicated surprise that stair climbing was not recognized

Subject indicated less sensors were desirable

Resulted in several updates to system

Second Evaluation Phase Seven sessions held in June 2007 Reliability and stability Session restart Improved sensor data handling Accelerometers Reduced to one Subject training Error recovery Each evaluation issue led to iterative improvements Instructions Automatically received on smartphone based on subject location and specified time elapse period Goals were attached to activity choices; outdoor walking pace and stairs vs. elevator choice Inclusion of the Olin Science Building at Harvey Mudd Subject were asked to acknowledge the receipt of an instruction via a smartphone button, otherwise session was suspended Packaging Easier to replace batteries Improvement in wiring and the addition of an external power switch

Seven sessions held in June 2007

Reliability and stability

Session restart

Improved sensor data handling

Accelerometers

Reduced to one

Subject training

Error recovery

Each evaluation issue led to iterative improvements

Instructions

Automatically received on smartphone based on subject location and specified time elapse period

Goals were attached to activity choices; outdoor walking pace and stairs vs. elevator choice

Inclusion of the Olin Science Building at Harvey Mudd

Subject were asked to acknowledge the receipt of an instruction via a smartphone button, otherwise session was suspended

Packaging

Easier to replace batteries

Improvement in wiring and the addition of an external power switch

Evaluation Overview Seven subjects: Five males, two females Five in their twenties, one in forties, one in fifties Experiment sessions lasted from 30 minutes to 1 hour Each evaluation was remotely monitored by using the Google Maps API A web page was created that had access to entire session data Web page displayed subject location as well as feedback on a map in realtime Allowed signaling of potential problems and correction notification to subject

Seven subjects:

Five males, two females

Five in their twenties, one in forties, one in fifties

Experiment sessions lasted from 30 minutes to 1 hour

Each evaluation was remotely monitored by using the Google Maps API

A web page was created that had access to entire session data

Web page displayed subject location as well as feedback on a map in realtime

Allowed signaling of potential problems and correction notification to subject

Course

Evaluation #1 Subject was male in his twenties Subject did not use stairs at Olin and Sprague, which was correctly identified by system On the way back, subject used stairs at ACB, but only a small percentage of the sequence was correctly identified. Data delay transmission also played a factor in incorrect recognition Interview revealed subject got lost inside Olin and had also thought Sprague Library stairs were off-limits Subject training modified to emphasize architecture inside Olin and Sprague

Subject was male in his twenties

Subject did not use stairs at Olin and Sprague, which was correctly identified by system

On the way back, subject used stairs at ACB, but only a small percentage of the sequence was correctly identified. Data delay transmission also played a factor in incorrect recognition

Interview revealed subject got lost inside Olin and had also thought Sprague Library stairs were off-limits

Subject training modified to emphasize architecture inside Olin and Sprague

Evaluation #2 Subject was female in her twenties Subject was briefed in more details about Olin and Sprague, but lost way inside Olin Extra walking inside Olin caused incorrect feedback Subject had to wait a long time outside Sprague as she was standing closer to Olin Inside Sprague, subject used elevator to go upstairs, but used the stairs to go down when she received her feedback At instruction #9, the session had to be aborted as incorrect GPS data caused the system to not send the next instruction Course was modified slightly to make it easier to trigger instruction #9

Subject was female in her twenties

Subject was briefed in more details about Olin and Sprague, but lost way inside Olin

Extra walking inside Olin caused incorrect feedback

Subject had to wait a long time outside Sprague as she was standing closer to Olin

Inside Sprague, subject used elevator to go upstairs, but used the stairs to go down when she received her feedback

At instruction #9, the session had to be aborted as incorrect GPS data caused the system to not send the next instruction

Course was modified slightly to make it easier to trigger instruction #9

Evaluation #3 Subject was male in his twenties Subject lost his way to the Olin building Subject was guided back on course using text messaging to smartphone Subject used stairs inside Olin and got correct feedback Inside Sprague, subject was going to use stairs, but decided on sharing an elevator ride up The subject received correct feedback at Sprague At ACB, the subject’s stair walking sequence was correctly recognized Exterior pictures of Olin were taken and shown to subjects to reduce chances of getting lost

Subject was male in his twenties

Subject lost his way to the Olin building

Subject was guided back on course using text messaging to smartphone

Subject used stairs inside Olin and got correct feedback

Inside Sprague, subject was going to use stairs, but decided on sharing an elevator ride up

The subject received correct feedback at Sprague

At ACB, the subject’s stair walking sequence was correctly recognized

Exterior pictures of Olin were taken and shown to subjects to reduce chances of getting lost

Evaluation #4 Subject was male in his twenties Subject could not find stairs inside Olin, extra activity caused incorrect feedback Subject had to wait a long time for instruction #6 as he was not close enough to Sprague Climbed stairs very quickly at both Sprague and ACB, which caused incorrect feedback Took a route for Sprague-Hagelbarger’s that was unanticipated, which caused delay in next instruction dispatch The instructions were modified to require the subject to wait outside Hagelbarger’s for the next instruction before proceeding inside Video clips were incorporated into training

Subject was male in his twenties

Subject could not find stairs inside Olin, extra activity caused incorrect feedback

Subject had to wait a long time for instruction #6 as he was not close enough to Sprague

Climbed stairs very quickly at both Sprague and ACB, which caused incorrect feedback

Took a route for Sprague-Hagelbarger’s that was unanticipated, which caused delay in next instruction dispatch

The instructions were modified to require the subject to wait outside Hagelbarger’s for the next instruction before proceeding inside

Video clips were incorporated into training

Evaluation #5 Subject was male in his twenties This was the second session with this subject, the first one was aborted due to priority conflict Subject used stairs in Olin, got correct feedback, but activity analysis showed low recognition of sequence Subject had to wait a long time for instruction #6 because he was standing under a shade Subject climbed stairs very quickly at Sprague which caused incorrect feedback On way back, subject forgot to acknowledge instructions which caused the session to end Subjects would now be escorted for a short while during training Subjects would now be instructed to stand under open sky while waiting for a GPS fix

Subject was male in his twenties

This was the second session with this subject, the first one was aborted due to priority conflict

Subject used stairs in Olin, got correct feedback, but activity analysis showed low recognition of sequence

Subject had to wait a long time for instruction #6 because he was standing under a shade

Subject climbed stairs very quickly at Sprague which caused incorrect feedback

On way back, subject forgot to acknowledge instructions which caused the session to end

Subjects would now be escorted for a short while during training

Subjects would now be instructed to stand under open sky while waiting for a GPS fix

Evaluation #6 Subject was male in his fifties There was high data transmission delay, causing several disconnections One disconnection caused by subject forgetting to acknowledge instruction Subject became conscientious inside Olin, tried to find stairs, but turned around and used elevator The extra activity caused an incorrect feedback Subject used elevator at Sprague, and got correct feedback The subject used stairs at ACB, but did not get correct feedback because of physical parameters

Subject was male in his fifties

There was high data transmission delay, causing several disconnections

One disconnection caused by subject forgetting to acknowledge instruction

Subject became conscientious inside Olin, tried to find stairs, but turned around and used elevator The extra activity caused an incorrect feedback

Subject used elevator at Sprague, and got correct feedback

The subject used stairs at ACB, but did not get correct feedback because of physical parameters

Evaluation #7 Subject was female in her forties Session had no problems with getting lost, or losing server connection Subject used elevator at Olin and got correct feedback Outside Sprague, subject started conversing with someone, which caused some delay Subject used elevator inside Sprague and got correct feedback Subject used stairs inside ACB, which was correctly recognized

Subject was female in her forties

Session had no problems with getting lost, or losing server connection

Subject used elevator at Olin and got correct feedback

Outside Sprague, subject started conversing with someone, which caused some delay

Subject used elevator inside Sprague and got correct feedback

Subject used stairs inside ACB, which was correctly recognized

Location Recognition Summary Eight instances of some delay in all sessions because of: Subject near structures e.g. sunshade Subject not close enough to building to trigger next instruction Subject placing GPS receiver in pockets One session had to be aborted because location misrecognition prevented new instruction from triggering

Eight instances of some delay in all sessions because of:

Subject near structures e.g. sunshade

Subject not close enough to building to trigger next instruction

Subject placing GPS receiver in pockets

One session had to be aborted because location misrecognition prevented new instruction from triggering

Activity Recognition Summary Nine instances of stair climbing at different buildings Out of nine instances of stair climbing, six were categorized as walking Major reasons: Subject running on stairs Activity model based on one person Single stair case used More time needed to modify activity recognition capabilities

Nine instances of stair climbing at different buildings

Out of nine instances of stair climbing, six were categorized as walking

Major reasons:

Subject running on stairs

Activity model based on one person

Single stair case used

More time needed to modify activity recognition capabilities

Subject Interview Summary What features you would like to see? Comparison, gaming, privacy, discrete packaging, a larger pool of messages Would you like to use such a device all day? Both older subjects expressed worry about using device at work Younger group enthusiastic about using the device in their daily activities Did you alter your behavior during the course based on feedback? Two subjects attributed their changed pace on way back from course because of the feedback they had received One subject consciously tried to look for the stairs for way down when feedback was received

What features you would like to see?

Comparison, gaming, privacy, discrete packaging, a larger pool of messages

Would you like to use such a device all day?

Both older subjects expressed worry about using device at work

Younger group enthusiastic about using the device in their daily activities

Did you alter your behavior during the course based on feedback?

Two subjects attributed their changed pace on way back from course because of the feedback they had received

One subject consciously tried to look for the stairs for way down when feedback was received

Connectivity and Stability Summary Eight instances of disconnection from server Data transmission delay to server Recoverable with session restart Two instances where subject did not acknowledge new instruction. One was not recovered as he was not aware that session had closed One instance of smartphone freezing Session restarted Connection stability affected by experiment time and location Sessions taking place late afternoon had more disconnections than other timings

Eight instances of disconnection from server

Data transmission delay to server

Recoverable with session restart

Two instances where subject did not acknowledge new instruction. One was not recovered as he was not aware that session had closed

One instance of smartphone freezing

Session restarted

Connection stability affected by experiment time and location

Sessions taking place late afternoon had more disconnections than other timings

Research Answers How could activity and location information be captured? Accelerometers and a GPS receiver placed on the user were adequate sources to capture this information Can these sources be feasibly used for choosing feedback related to the health choices of a user? The development and evaluation of HMSS has shown that raw data from these sources can be used to determine a user’s context, which in turn can help the system select an appropriate feedback Could feedback from the system be effective in changing behavior? The results showed mixed result in changing behavior. Also the results were demonstrated for a short term. The study did uncover a clue to demographic factors in acceptance of such a feedback mechanism. Further study is required

How could activity and location information be captured?

Accelerometers and a GPS receiver placed on the user were adequate sources to capture this information

Can these sources be feasibly used for choosing feedback related to the health choices of a user?

The development and evaluation of HMSS has shown that raw data from these sources can be used to determine a user’s context, which in turn can help the system select an appropriate feedback

Could feedback from the system be effective in changing behavior?

The results showed mixed result in changing behavior. Also the results were demonstrated for a short term. The study did uncover a clue to demographic factors in acceptance of such a feedback mechanism. Further study is required

Contributions An understanding of user attitude towards real time health feedback devices Knowledge gained about the subject and technical factors that can affect the outcome and results of mobile field experiments An exploration of how customized real time reference to physical parameters such as activity and walking pace could affect short-term behavior

An understanding of user attitude towards real time health feedback devices

Knowledge gained about the subject and technical factors that can affect the outcome and results of mobile field experiments

An exploration of how customized real time reference to physical parameters such as activity and walking pace could affect short-term behavior

Future Goals Context-awareness Increase activity and location recognition accuracy Use more data for context recognition e.g. weather Implement user definable feedback parameters Increase feedback message variety and quantity Reduce data transmission to server Enable customized activity modeling Reduce power consumption Publication: Article submitted to IEEE Pervasive Computing

Context-awareness

Increase activity and location recognition accuracy

Use more data for context recognition e.g. weather

Implement user definable feedback parameters

Increase feedback message variety and quantity

Reduce data transmission to server

Enable customized activity modeling

Reduce power consumption

Publication: Article submitted to IEEE Pervasive Computing

Questions

References S. Mitchell, M. D. Spiteri, J. Bates, and G. Coulouris, "Context-aware multimedia computing in the intelligent hospital," Proceedings of the 9th workshop on ACM SIGOPS European workshop: beyond the PC: new challenges for the operating system , pp. 13-18,2000. D. Siewiorek, A. Smailagic, J. Furukawa, A. Krause, N. Moraveji, K. Reiger, and J. Shaffer, "SenSay: a context-aware mobile phone," Wearable Computers, 2003. Proceedings. Seventh IEEE International Symposium on , pp. 248-249, 2003. A. K. Dey, "Understanding and Using Context," Personal and Ubiquitous Computing , vol. 5, no. 1, pp. 4-7, 2001. H. W. Gellersen, A. Schmidt, and M. Beigl, "Adding Some Smartness to Devices and Everyday Things," Proceedings of IEEE Workshop on Mobile Computing Systems and Applications 2000 (WMCSAA 2000) , 2000.

S. Mitchell, M. D. Spiteri, J. Bates, and G. Coulouris, "Context-aware multimedia computing in the intelligent hospital," Proceedings of the 9th workshop on ACM SIGOPS European workshop: beyond the PC: new challenges for the operating system , pp. 13-18,2000.

D. Siewiorek, A. Smailagic, J. Furukawa, A. Krause, N. Moraveji, K. Reiger, and J. Shaffer, "SenSay: a context-aware mobile phone," Wearable Computers, 2003.

Proceedings. Seventh IEEE International Symposium on , pp. 248-249, 2003.

A. K. Dey, "Understanding and Using Context," Personal and Ubiquitous Computing , vol. 5, no. 1, pp. 4-7, 2001.

H. W. Gellersen, A. Schmidt, and M. Beigl, "Adding Some Smartness to Devices and Everyday Things," Proceedings of IEEE Workshop on Mobile Computing Systems and Applications 2000 (WMCSAA 2000) , 2000.