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1. Micro-Blog: Sharing and Querying Content Through Mobile Phones and Social Participation Presented by: Muhammad S. Karim
2. The Vision A Virtual Information Telescope
3. What is the idea of Micro-blogging? 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.
4. Services and Applications Content Sharing
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.
Content Querying
Micro-Blog allows location specific queries.
Phones reply to query that are posted on to Google-map as a new micro-blog.
Content Floating
Metaphorically, virtual “sticky notes” floating in air.
Pushed on phones when user enters a region.
5. Services and Applications (cont..)
Potential Applications:
Tourism
Micro-news
Micro-Alerts
Social Collaboration
6. Research Problems?
Design considerations poses research problems:
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?).
7. Design Considerations Energy-Accuracy Tradeoff
Continuous GPS sinks major portion of energy.
8. Design Considerations (cont..) Solutions to achieve energy-efficient localization?
Multiplex between localization: GPS/WiFi/GSM.
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)
9. Design Considerations (cont..) Incentives?
No incentives no reply to queries!
Credit system for queries?
Location Privacy?
3 blogging modes proposed:
Public/Social/Private.
Users set privacy policy.
Content Inaccuracy and Spam?
Introduce configurations to allow level of tolerated distraction.
Use reputations to encourage content integrity.
10. System Architecture Phones periodically update the Micro-blog server with their own locations.
The server maintains a per-phone localization database.
Queries are active for a pre-specified lifetime.
Server also ‘pushes’ location-specific blogs to phones that arrives on a location (and that are subscribed to a channel related to that location).
Phones periodically update the Micro-blog server with their own locations.
The server maintains a per-phone localization database.
Queries are active for a pre-specified lifetime.
Server also ‘pushes’ location-specific blogs to phones that arrives on a location (and that are subscribed to a channel related to that location).
11. System Implementation 1. Phone Client
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.
12. System Implementation (cont..) 2. Web-Infrastructure
Accepts TCP connection from phones.
Uses a relational DB in the backend (MySQL).
Web-application allows users to login, and:
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.
13. Evaluation Localization error with a combined GPS and WiFi scheme:
More GPS samples offer diminishing returns
But energy cost increases linearly
14. Prototype
15. Limitations and Future Work
Credibility of the case-study performed.
only 12 users, and 1 type of phone.
Integration with a Social Network Application
make your own or use an exiting one?
Identification and filtering of false contents.
Exploiting Accelerometers for Localization.
16. References:
Micro-Blog webpage at Duke’s SyNRG lab:
http://synrg.ee.duke.edu/microblog.html
Romit’s slides presented at @ MobiSys 2008