Adaptive Mobile Applications

Thomas Kunz

Systems and Computer Engineering

Carleton University

http://kunz-pc.sce.carleton.ca/

tkunz@sce.carleton.ca

Related Work

Typically, related work focuses on bandwidth variation

Other resources are also constrained (memory, power, CPU capabilities) and may vary over time

Majority of solutions: introduce proxy between client (application executing on mobile device) and server, proxy compresses and filters data stream

sometimes, degree of compression depends on available bandwidth

user mobility often not addressed/supported

Other solutions:

view mobile purely as User Interface (WWW browsers, Teleporting, ....)

partition client application between mobile and proxy

partition directed by application (Rover, MaROS, ....)

partition transparent to application (our own focus)

Mobility: Issues and Ideas

As mobile devices roam, the proxy (or proxies) might have to migrate as well:

schemes are only efficient if proxy is on direct path between mobile and correspondent host

however, not every move requires a proxy migration

When to migrate: performance question

e.g., when are advantages of migration higher than costs?

How to migrate: infrastructure question

Consequences of migration: mobility models, simulations

e.g., what happens if all cellular subscribers move into same cell (the one that covers the big shopping mall)

Proposed Architecture

Summary of Achievements

Mobile IP software under Linux, including route optimization

Comma (provides feedback about execution environment): redesigned to deal with limited devices such as Palm Pilots

Trace data analysis (Bell’s Microbrowser) and performance prediction models: scalability of approach

Mobile code toolkit for Windows CE (DOMT), redesigned for Palm Pilots based on KVM (KMOT)

Sample applications (MPEG and MP3 player), based on Objectspace Voyager and our own toolkits

Summary of Achievements

Explored mobile applications in WAP

Explored traditional adaptation concepts (filter/compress data stream)

Prototype for adaptive web browsing

“Controls,” both interactive and configuration

Known standards & data types enable transcoding at proxy

In concert with Comma & other tools for environmental information

Prototype of “Geo-web” for geographic organization of information

Adaptive map browsing for constrained environments

Summary of Achievements

Training of Highly Qualified Personnel:

Carleton:

2 Research Associates (Thomas Barry, Yang Wang)

6 Master’s students graduated

3 additional students expected to graduate in 2001/2

Waterloo:

2 Master’s students graduated

3 additional graduate students expected to graduate in 2001

1 PhD expected in 2002

Publications:

1 book chapter

2 journal publications

4 refereed conference/workshop papers

7 others (position papers, conferences with abstract reviewed, …)

Trace Collection Infrastructure

The Big Picture:
Traffic Profile (Jan. – Dec. 2000)

Sessions: Average Number of Concurrent Sessions, December 2000

WAP vs. WWW Traffic

Some similarities:

Periodicity

Daily patterns (and to some extent half-daily patterns)

Weekly patterns (and to some extent half-weekly patterns)

Not enough trace data to confirm/test for seasonal patterns

Self-similarity (Hurst Parameter between 0.79 and 0.82)

But also some differences:

Smaller packets (95% of all packets less than 220 bytes)

Shorter sessions

Traffic more balanced (dowlink traffic “only” about 3 times as much data as uplink traffic)

No growth trend in data presented in paper, but long-term growth trend clearly visible since

Performance Prediction Models: Simple Model

Performance Prediction Model: Adding Proxy Layer

Model Predictions

Capacity limitations: between 8 to 50 concurrent clients

Effects of more powerful CPU or parallel gateway servers

Effects of adding a proxy layer

Changes in user behavior

New/more complicated services

Mobile Code Toolkits

Exploration with Voyager, a free mobile code toolkit based on Java

Handoff between proxies

Handoff between proxies and handheld device (ongoing)

Development of own Toolkits for PDAs:

Java-based toolkit for Windows CE devices: DOMT

KVM-based toolkit for Palm Pilot/Handspring Visors: KMOT (KVM-based Mobile Object Toolkit)

Visualizing code mobility

Case Study: MP3 Player over DOMT Required Info: Application Object Graph

Objects

Inter-Object Communication

Experimental Results (DOMT)

Implemented MP3 player, decoder (set of heavily communicating objects) can execute locally or remotely

Various performance experiments, study impact of

Available Bandwidth (19.2 kbps – 2 Mbps)

Relative CPU speed (Mobile CPU: Proxy CPU)

1:4 for laptop as client device

1:116 for Windows CE palmtop as client device

Results:

for high bandwidth and slow client, offloading decoder to proxy can speed up application performance by a factor of 20 and reduce power consumption by 95%

For faster client devices, independent of bandwidth, no benefit (actually worse performance) when decoding sound samples in access network

KMOT: Mobile Code Toolkit for KVM

Based on DOMT, redesigned toolkit to fit KVM constrains:

No serialization

No reflection mechanism

Experiments with “MP3 player” clone (time per frame in ms):

Visualizing Mobile Code Executions

Applications involving mobile code are complex:

All the problems of parallel and distributed applications (concurrency, scale, non-determinism, etc.)

Additional problem: where are mobile components?

Visual tools used widely in parallel and distributed programming environments for program understanding, fault and performance debugging, …

Some popular visualization tools:

Poet

XPVM

Polka

Paragraph

All support visualizing execution dynamics, none explicitly shows mobility of code

Event Visualization

Event Visualization (cont)

Conclusions and Future Work

Work to date shows feasibility of approach

MP3 player: improvement in performance and reduction in power when offloading decoding from slow handset to access network, if there is enough bandwidth

Platforms: Windows CE, Palm Pilot

Future Work: future 3G systems all IP, devices all support JVM/KVM/Brew/….

Enhance KMOT (KVM-based Mobile Object Toolkit)

Automatic construction of the object graph

Design of an efficient partition strategies

Apply to multimedia applications

Larger-scale tests (multiple devices, proxies, more complicated network topology)

Other topics of interest: location and location-based services, ad-hoc access networks, etc.


	Thomas Kunz
	Systems and Computer Engineering
	Carleton University
	http://kunz-pc.sce.carleton.ca/
	tkunz@sce.carleton.ca


Typically, related work focuses on bandwidth variation
Other resources are also constrained (memory, power, CPU capabilities) and may vary over time
Majority of solutions: introduce proxy between client (application executing on mobile device) and server, proxy compresses and filters data stream
	sometimes, degree of compression depends on available bandwidth
	user mobility often not addressed/supported
Other solutions:
	view mobile purely as User Interface (WWW browsers, Teleporting, ....)
	partition client application between mobile and proxy
		partition directed by application (Rover, MaROS, ....)
		partition transparent to application (our own focus)


	As mobile devices roam, the proxy (or proxies) might have to migrate as well:
		schemes are only efficient if proxy is on direct path between mobile and correspondent host
		however, not every move requires a proxy migration
	When to migrate: performance question
		e.g., when are advantages of migration higher than costs?
	How to migrate: infrastructure question
	Consequences of migration: mobility models, simulations
		e.g., what happens if all cellular subscribers move into same cell (the one that covers the big shopping mall)


	Mobile IP software under Linux, including route optimization
	Comma (provides feedback about execution environment): redesigned to deal with limited devices such as Palm Pilots
	Trace data analysis (Bell’s Microbrowser) and performance prediction models: scalability of approach
	Mobile code toolkit for Windows CE (DOMT), redesigned for Palm Pilots based on KVM (KMOT)
	Sample applications (MPEG and MP3 player), based on Objectspace Voyager and our own toolkits


	Explored mobile applications in WAP
	Explored traditional adaptation concepts (filter/compress data stream)
	Prototype for adaptive web browsing
		“Controls,” both interactive and configuration
		Known standards & data types enable transcoding at proxy
		In concert with Comma & other tools for environmental information
	Prototype of “Geo-web” for geographic organization of information
	Adaptive map browsing for constrained environments


Training of Highly Qualified Personnel:
	Carleton:
		2 Research Associates (Thomas Barry, Yang Wang)
		6 Master’s students graduated
		3 additional students expected to graduate in 2001/2
	Waterloo:
		2 Master’s students graduated
		3 additional graduate students expected to graduate in 2001
		1 PhD expected in 2002
Publications:
	1 book chapter
	2 journal publications
	4 refereed conference/workshop papers
	7 others (position papers, conferences with abstract reviewed, …)


Some similarities:
	Periodicity
		Daily patterns (and to some extent half-daily patterns)
		Weekly patterns (and to some extent half-weekly patterns)
		Not enough trace data to confirm/test for seasonal patterns
	Self-similarity (Hurst Parameter between 0.79 and 0.82)
But also some differences:
	Smaller packets (95% of all packets less than 220 bytes)
	Shorter sessions
	Traffic more balanced (dowlink traffic “only” about 3 times as much data as uplink traffic)
	No growth trend in data presented in paper, but long-term growth trend clearly visible since


	Capacity limitations: between 8 to 50 concurrent clients
	Effects of more powerful CPU or parallel gateway servers
	Effects of adding a proxy layer
	Changes in user behavior
	New/more complicated services


	Exploration with Voyager, a free mobile code toolkit based on Java
		Handoff between proxies
		Handoff between proxies and handheld device (ongoing)
	Development of own Toolkits for PDAs:
		Java-based toolkit for Windows CE devices: DOMT
		KVM-based toolkit for Palm Pilot/Handspring Visors: KMOT (KVM-based Mobile Object Toolkit)
	Visualizing code mobility


Implemented MP3 player, decoder (set of heavily communicating objects) can execute locally or remotely
Various performance experiments, study impact of
	Available Bandwidth (19.2 kbps – 2 Mbps)
	Relative CPU speed (Mobile CPU: Proxy CPU)
		1:4 for laptop as client device
		1:116 for Windows CE palmtop as client device
Results:
	for high bandwidth and slow client, offloading decoder to proxy can speed up application performance by a factor of 20 and reduce power consumption by 95%
	For faster client devices, independent of bandwidth, no benefit (actually worse performance) when decoding sound samples in access network


	Based on DOMT, redesigned toolkit to fit KVM constrains:
		No serialization
		No reflection mechanism
	Experiments with “MP3 player” clone (time per frame in ms):


	Applications involving mobile code are complex:
		All the problems of parallel and distributed applications (concurrency, scale, non-determinism, etc.)
		Additional problem: where are mobile components?
	Visual tools used widely in parallel and distributed programming environments for program understanding, fault and performance debugging, …
	Some popular visualization tools:
		Poet
		XPVM
		Polka
		Paragraph
	All support visualizing execution dynamics, none explicitly shows mobility of code


Work to date shows feasibility of approach
	MP3 player: improvement in performance and reduction in power when offloading decoding from slow handset to access network, if there is enough bandwidth
Platforms: Windows CE, Palm Pilot
Future Work: future 3G systems all IP, devices all support JVM/KVM/Brew/….
	Enhance KMOT (KVM-based Mobile Object Toolkit)
		Automatic construction of the object graph
		Design of an efficient partition strategies
	Apply to multimedia applications
	Larger-scale tests (multiple devices, proxies, more complicated network topology)
	Other topics of interest: location and location-based services, ad-hoc access networks, etc.