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

The Vision A Virtual Information Telescope

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.

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.

Services and Applications (cont..)

Potential Applications: Tourism Micro-news Micro-Alerts Social Collaboration

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?).

Design Considerations Energy-Accuracy Tradeoff

Continuous GPS sinks major portion of energy.

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)

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.

System Architecture

Block diagram of the Micro-Blog software architecture

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.

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.

Evaluation Localization error with a combined GPS and WiFi scheme:

More GPS samples offer diminishing returns But energy cost increases linearly

Prototype

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

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.

References: Micro-Blog webpage at Duke’s SyNRG lab: http://synrg.ee.duke.edu/microblog.html Romit’s slides presented at @ MobiSys 2008