1. Micro-Blog : Sharing and Querying Content Through Mobile Phones and Social Participation Presented by: Muhammad S. Karim By S. Gaonkar, J. Li, R. Choudhury, L. Cox, A. Schmidt - MobiSys 2008

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 Block diagram of the Micro-Blog software architecture

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 Ref: http://synrg.ee.duke.edu/microblog.html

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 http://synrg.ee.duke.edu/microblog.html  Romit’s slides presented at @ MobiSys 2008