cmsc 828s / saket navlakha / 1 sensor web browsing the physical world in real-time by: vincent tao

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CMSC 828S / Saket Navlakha / 1

Sensor Web

Browsing the physical world in real-time

By: Vincent Tao

CMSC 828S / Saket Navlakha / 2

History

• Conceived: 1997, NASA/Jet Propulsion Laboratory

CMSC 828S / Saket Navlakha / 3

History

• Conceived: 1997, NASA/Jet Propulsion Laboratory

• Idea: – sensor chips to monitor and control

environment– sensations transmitted via internet in real-time

CMSC 828S / Saket Navlakha / 4

History

• Conceived: 1997, NASA/Jet Propulsion Laboratory

• Idea: – sensor chips to monitor and control

environment– sensations transmitted via internet in real-time

• Why is this different?

CMSC 828S / Saket Navlakha / 5

History

• Conceived: 1997, NASA/Jet Propulsion Laboratory

• Idea: – sensor chips to monitor and control environment– sensations transmitted via internet in real-time

• Why is this different?– Cheaper sensors more possibility– Networked (not individual) sensors

CMSC 828S / Saket Navlakha / 6

Example: Restaurant Waiting Time

CMSC 828S / Saket Navlakha / 7

Problems: Interoperable

• Interoperable– In-site (on-site) sensors

• Measuring physical properties of an area

– Remote sensing• Via radiation reflected or emitted from object• GPS

– Web

CMSC 828S / Saket Navlakha / 8

Problems: Interoperable

• Interoperable– In-site (on-site) sensors

• Measuring physical properties of an area

– Remote sensing• Via radiation reflected or emitted from object• GPS

– Web

• Implies data formatting standards (Open GIS)– Web Map Service, Geographic Markup Language,

SensorML, etc

CMSC 828S / Saket Navlakha / 9

CMSC 828S / Saket Navlakha / 10

Problems: Intelligent

• Intelligent– Sense environment and respond– Communicate amongst each other– Data integration

CMSC 828S / Saket Navlakha / 11

Problems: Flexible

• Flexible– Different types of sensors

• Deterministic• Triggered• On-demand

– Broken sensors– Fault tolerant to noise, redundant– Weather conditions– Easy deployment

CMSC 828S / Saket Navlakha / 12

Problems: Scalability & Size

• Scalability– Large number of interacting sensors– Large number of simultaneous requests– Efficiently locate sensors– Adapt to sensor join/leaves

• Size: does one size fit all?

CMSC 828S / Saket Navlakha / 13

Problems: Scalability & Size

• Scalability

• Size: does one size fit all?– smaller panels (less energy harvesting)– smaller antennae (less radio range)– smaller batteries (less power)– larger sensors (harder to manage, intrusive)

What about tiered architecture?

CMSC 828S / Saket Navlakha / 14

SenseWeb

• Microsoft Research project

• Goals:– Ease of data publication– Application-to-application compatibility– Primitives to query live sensors

Create SensorNet

• Display: MSN Virtual Earth

CMSC 828S / Saket Navlakha / 15

CMSC 828S / Saket Navlakha / 16

SenseWeb: Architecture

• Data Publishing Toolkit (DPT)– Publishes sensor metadata (location/type) to GeoDB– Publishes sensor data in response to queries

• Uses sensor ontology standards• GeoDB

– Indexes metadata; uses hierarchical triangular mesh (HTM)

– Queries submitted by keyword, location, etc.

CMSC 828S / Saket Navlakha / 17

SenseWeb: Architecture

• Data Publishing Toolkit• GeoDB• Aggregator

– Data integration: mashes sensor data with client side GUI (e.g. MSN Virtual Earth overlay)

– User query GeoDB relevant sensors DPT real-time data aggregate/summarize

CMSC 828S / Saket Navlakha / 18

SenseWeb: Architecture

• Advantages– Data owner only talks to DPT– End users only browse web page and query

data GeoDB and Aggregator transparency

• Disadvantages?

CMSC 828S / Saket Navlakha / 19

Conclusion

• Ubiquity & Invisibility• Overview of problems• Four layers

– Sensor: sensor design, materials, etc– Communication: protocols, standards, etc– Location: routing, addressing, etc– Information: data integration, distribution, etc

• Which can be different? Which need standardization?

CMSC 828S / Saket Navlakha / 20

Conclusion

• Next: algorithms & techniques to solve problems (e.g. HTM, P2P communication, statistical data modeling, more applications)

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