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Challenges in Location-Aware
Computing
Cynthia A. Patterson, Richard R. Muntz,
and Cherri M. Pancake
IEEE Pervasive Computing 2003
Outline
 Location-Aware
Computing
 Location-sensing infrastructure
 Adaptive resource management
 Other research challenges

Conclusion
Independent Technologic
Location-aware computing
Context-aware computing-反應到real-world context
 User identity
 Physical location
 Current Condition
 Time of day,date,season
 User asleep or awake
 Location information and identity是主要關鍵
 Location-aware computing
 Mobile computing
 Location sensing
 Wireless networking

Hardware for mobile computing
Integrating mobile hardware system and seamlessly
bridge user’s desktop
 Design issue:
 battery,size,weight
 Security
 Performance and reliability
 Energy source

seamlessly bridge user’s desktop
Location sensing

Global Positioning System (GPS)是個方法,目前大
概$100,越來越廣泛
GPS

一些問題考量:
 不能使用於室內,特別是金屬建築
 對於一些應用準確度還是不夠好
 使用coordinate system
 Weight ,cost,energy consumption
 Other

location-sensing mechanism
一按即發出訊號的信號器,行動徽章…
LAR(location aided routing)
MESH: multi-eye spiral-hopping routing
How to serach location ?
PDA
Tablet PC
PDA
PDA
Tablet PC
PDA
Notebook
PDA
Notebook
PDA
Tablet PC
802.11 Ad Hoc mode
PDA
PDA
PDA
PDA
Tablet PC
Notebook
Notebook
PDA
PDA
Tablet PC
Tablet PC
Location-Aware Multicast Protocol for Bluetooth
Location-Aware Multicast Protocol for Bluetooth
利用flooding達成收集location information
Location sensing ?

A mechanism for discovering
spatial relationships between
objects
Variety of Mechanisms
ACTIVE
e.g. radar and
reflective sonar
systems
System emits signal, deduces
target location from distortions
in signal returns
CO-OPERATIVE
Target
cooperates
with the
system
ORL Active Bat, GALORE
Panel, AHLoS, GPS, MIT
Cricket, UNC HighBall
PASSIVE
Microsoft RADAR
BLIND
Acoustic “blind
beamforming” (Yao)
System deduces location from
observation of signals that are
“already present”
System deduces location of
target without a priori
knowledge of its
characteristics
?
Definitely no “one size fits all” solution
ACTIVE

Target
Synchronization channel
Ranging channel
System emits signal, deduces target location from
distortions in signal returns
CO-OPERATIVE

Target cooperates with the
system
Target
Synchronization channel
Ranging channel
PASSIVE

Target
Synchronization channel
Ranging channel
System deduces location from observation of signals that
are “already present”
Target
Synchronization channel
Ranging channel
BLIND

System deduces location of target without a priori
knowledge of its characteristics
?
Wireless communications
Voice commnication(cell phones)
 IEEE802.11 WLAN
 Bluetooth
 IrDA

Power is important factor for mobile device
 Other: frequency,bandwidth,range,density of wired
infrastructure
 Trade-offs 就要看需求來決定了

Bluetooth
Using Bluetooth Technology
無線區域網路技術比較表
無線區域網路技術比較表
無線區域網路技術比較表
Location-sensing Infrastructure

Location-based services




GPS and other localization technologies
Wireless communication
Mobile computing
Location-sensing infrastructure can
become commercially viable
Technology-independent location sensing
因素太多,於是討論發展a technology-independent ,
high-level software application programming
interface for location-sensing.
 發展middleware level API將有助於long-lived
applications,而且遇到的障礙將刺激發展new
location-sensing technologic.
 API最好是open, specification, dynamically
combining location information from multiple source

Opportunistic data acquisition
Cars,Road maintenance personnel using data-mining
and visualization software, GPS,Real-time system,
可以防止事故,節省能量,預防結冰
 Challenge
 Address scalability
 Mobile sensor source
 Appropriate information-sharing policy
 Privacy
 Not sacrificing functionality(功能)

End-to-end control of location information
Cell-based location sensing,loss of privacy
 Historical location information可以幫助預測user’s
typical movement
 需要發展end-to-end control of location information,
也就是需要好的 access control mechanism,得到正
確的資料,不正確的丟棄,而且利用location
information加強Security機制

Test bed for experimental research

Lack adequate large-scale experimental infrastructure,
可以促進發展commercialization







Standard protocols
APIs
Platform-independent capability
Scalability
Different network nodes information conflicting
Resource management
Static-mobile load balancing
NS2
Adaptive Resource Management

Cyber foraging



Infostation


Guide a mobile user from a bandwidthimpoverished to a bandwidth-rich enviroment.
This technique is cyber foraging.
Temporarily extends a mobile computer’s
resources by pointing to remote resources.
Provide low-cost,low-power access information
services
處理這些事情可以使用surrogates(代理人)的方法,
對使用者無察覺無狹縫,要有選擇代理人的方法
Tracking and predicting location
例如:eletronic map結合tracking and predicting
location 選擇最好的路
 物體的移動和速度對於location資料的正確性將
是挑戰, trade-offs 頻寬浪費和location資料正確性
 所以開始研究預測路徑,典型的home-office-home,
但是如果不正常的移動,就會無法完美預測,而且
必須發展認證或確認身分的機制
 前提還要有其他技術支援,如public transportation,
good software回應user的要求

Bluetooth Location Networks
Location Tracking Protocol in Sensor Network
Other Research challenges

Geospatial database and data mining




Human interaction with geospatial information


Database integrate geospatial data
Query language and algorithmic分解data space and time
Data mining and Data analysis and evaluation benefit
缺乏綜合framework來理解human interaction with
geospatial information
New location information research
 Smart dust sensors-農業,…
Wireless Sensor Networks

New technologies have
reduced the cost, size and
power of micro-sensors
and wireless interfaces
Circulatory Net
Sensing
Networking

Systems can



Computation
Environmental Monitoring
Embedded into environment
Sense phenomena at close range
Systems will revolutionize



Environmental monitoring
Disaster scenarios
Structure Response
Some Networked Sensor Node Developments
LWIM III
AWAIRS I
UCLA, 1996
UCLA/RSC 1998
Geophone, RFM
Geophone, DS/SS
radio, PIC, star
Radio, strongARM,
network
Multi-hop networks
Sensor Mote
UCB, 2000
RFM radio,
PIC
WINS NG 2.0
Sensoria, 2001
Node development
platform; multisensor, dual radio,
Linux on SH4,
Preprocessor, GPS
Processor
Real-World Experiences Ad Hoc Sensor Network
Gateway node
Each audience member is
given a voting device,
users respond to questions
by pressing the buttons.
100 node voting devices
in the San Francisco
Moscone Convention
Center. Routing topology
using DSDV protocol.
Conclusion

IT Roadmap report
(http://www.cstb/project_geospatial.html)