Micro-Blog: Sharing and Querying Content
Through Mobile Phones and Social Participation
- MobiSys 2008
By S. Gaonkar, J. Li, R. Choudhury, L. Cox, A. Schmidt
Presented by: Muhammad S. Karim
The Vision
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A Virtual Information Telescope
What is the idea of Micro-blogging?
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Mobile-phone users record multimedia blogs on-the-fly
using phone’s physical sensors (camera, voice, GPS,
accelerometer etc.)
The micro-blogs are geo-tagged and uploaded in a remote
server.
Server displays micro-blogs from around the world in a
web-browser using a visualization service (e.g. Google
maps)
The system provides content querying service.
Services and Applications
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Content Sharing
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Content Querying
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Users blog on mobile phones using video, audio, pictures, text etc.
Micro-Blog phone client geo-tags blog, upload to server over
WiFi/GPRS/…
Micro-Blog server positions blog on Google-maps.
Internet users can explore and zoom on the maps.
Micro-Blog allows location specific queries.
Phones reply to query that are posted on to Google-map as a new
micro-blog.
Content Floating
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Metaphorically, virtual “sticky notes” floating in air.
Pushed on phones when user enters a region.
Services and Applications (cont..)
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Potential Applications:
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Tourism
Micro-news
Micro-Alerts
Social Collaboration
Research Problems?
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Design considerations poses research problems:
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How can the localization service be energy aware?
Energy-Accuracy tradeoff!
Incentives for participation?
Location privacy.
Content Inaccuracy and Spam (How to filter bad contents?).
Design Considerations
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Energy-Accuracy Tradeoff
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Continuous GPS sinks major portion of energy.
Design Considerations (cont..)
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Solutions to achieve energy-efficient localization?
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Multiplex between localization: GPS/WiFi/GSM.
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Perform WiFi sampling by default.
Sample GPS location when no macro movement.
When movement, trigger infrequent WiFi: t(i) ,t(i+1) ,t(i+2) …
Location at t(i) is extrapolation from last GPS location at t(0)
Design Considerations (cont..)
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Incentives?
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Location Privacy?
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No incentives no reply to queries!
Credit system for queries?
3 blogging modes proposed:
Public/Social/Private.
Users set privacy policy.
Content Inaccuracy and Spam?
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Introduce configurations to allow level of tolerated distraction.
Use reputations to encourage content integrity.
System Architecture
Block diagram of the Micro-Blog software architecture
System Implementation
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1. Phone Client
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The software requires access to the a) location services, b) network services, c)
file-system on the phone.
Maintains states to minimally interrupt the normal operations of the phone.
System Implementation (cont..)
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2. Web-Infrastructure
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Accepts TCP connection from phones.
Uses a relational DB in the backend (MySQL).
Web-application allows users to login, and:
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a) Accept request for blogs from any region of the world,
b) Uses a visualization service that displays the blogs on Google maps,
c) Accepts user queries with marked regions and find phones in the DB
that are associated with the region,
d) When a response arrives for a query, associate it with the query in
DB and send response back to the query-originator.
Evaluation
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Localization error with a combined GPS and WiFi scheme:
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More GPS samples offer diminishing returns
But energy cost increases linearly
Prototype
Ref:
http://synrg.ee.duke.edu/microblog.html
Limitations and Future Work
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Credibility of the case-study performed.
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Integration with a Social Network Application
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only 12 users, and 1 type of phone.
make your own or use an exiting one?
Identification and filtering of false contents.
Exploiting Accelerometers for Localization.
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References:
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Micro-Blog webpage at Duke’s SyNRG lab:
http://synrg.ee.duke.edu/microblog.html
Romit’s slides presented at @ MobiSys 2008