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UbiLearn2006 1
SULS
The Design Concept of a Simple Ubiquitous Learning System – SULS
一個簡易的無所不在學習系統 SULS 之設計概念
江振瑞 葉明貴 黃宇立
中央大學 資訊工程系
UbiLearn2006 4
SULS
Introduction(1/4)
The improvement of Wireless
communications and Micro
Electro-Mechanical Systems (MEMS) leads to an age of Ubiquitous Computing
UbiLearn2006 5
SULS
Introduction(2/4)
Learning Systems also step
from e-Learning, Mobile-Learning to Ubiquitous Learninging
With the help of the positioning ability
of learning devices and smart objects,
the ubiquitous learning system become context aware
UbiLearn2006 7
SULS
Introduction(4/4)
A design concept, SULS – Simple
Ubiquitous Learning System, is proposed
here to support ubiquitous learning
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SULS
Preliminary(1/7)
GPS (Global Positioning System)Line-of-sight between satellite and point nodesynchronous timer around three satellites
APS (Ad-hoc Positioning System)Not need LOS and synchronous timer
Based on DVRP(Distance Vector Routing Protocol) and the trilateration positioning technologyDV-Distance, one of the APS methods, is used in SULS
UbiLearn2006 10
SULS
Preliminary(2/7)
Anchor node
Anchor node
Broadcast it’s Position
Anchor nodeRSSI(received signal strength indicator)
UbiLearn2006 12
SULS
Preliminary(4/7)
RFID reader
DataClockEnergy
Contactless data carrier
= Transponder
Application
Coupling element(coil, microwave antenna)
RFID (radio frequency identity)Compose of reader, tag and application
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SULS
Preliminary(5/7)
RFID (radio frequency identity)Three kinds of tag
• Passive tag – no self battery– the simplest one
• semi-active tag • active tag
UbiLearn2006 14
SULS
Preliminary(6/7)
RFID reader
DataClockEnergy
Contactless data carrier
= Transponder
Application
Coupling element(coil, microwave antenna)
RFID (radio frequency identity)How passive tag works?
UbiLearn2006 15
SULS
Preliminary(7/7)
RFID(radio frequency identity)Working frequencies in the worldwide
• 135KHz • 13.5MHz• 433.92MHz• 860~930MHz(UHF)• 2.45GHz and 5.8GHz
The UHF tag can be read at a distance about 10m.
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SULS
SULS(1/7)
SULSSimple Ubiquitous Learning System integratestwo existent technologies
APSRFID
three newly developed technologies
Farthest tag forwarding
Tag-assisted positioning
Multi-media data in-network cache
UbiLearn2006 18
SULS
SULS(2/7)
Farthest tag forwardingBack-off time = ((L-R)/L) x B
Where R:signal source distance
L:the farthest signal distance
B:the maximum back-off time
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SULS
SULS(3/7)
The farthest signal
distance250 m200 m
50 m
• The farthest signal distance= 250 m– Far away from 50m((250-50)/250)B=0.8B
– Far away from 200m ((250-200)/250B=0.2B
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SULS
SULS(5/7)
Tag-assisted positioningAnchor node can be located by
• GPS
• Tags that have position information and are attached to smart objects
Other nodes can be located by three GUIDE NODEs
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SULS
SULS(6/7)
Multi-media data in-network
cacheGUIDE NODE has multi-media data of smart objects
Use cache to reduce network traffic and GUIDE NODE loading
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SULS
Conclusion
SULS a Simple Ubiquitous Learning System
a low cost and efficient Ubiquitous Learning system
use • simple devices
– Learning devices with mobile ability
– Few have RFID readers (plus GPS)
• three newly developed technologies– Farthest tag forwarding
– Tag-assisted positioning
– Multi-media data in-network cache