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Spontaneous Social-Networking on Smartphones using Delay-Tolerant Networks

Spontaneous Social-Networking on Smartphones using Delay-Tolerant Networks. CP4101 B.COMP DISSERTATION (H101850 ). CHEN JUNCHENG. SUPERVISOR: PROF CHAN MUN CHOON. Agenda. Motivation Application Description Challenges Faced (and Solutions) Evaluation Testing Demo.

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Spontaneous Social-Networking on Smartphones using Delay-Tolerant Networks

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  1. Spontaneous Social-Networkingon Smartphones using Delay-Tolerant Networks CP4101 B.COMP DISSERTATION (H101850) CHEN JUNCHENG SUPERVISOR: PROF CHAN MUN CHOON

  2. Agenda • Motivation • Application Description • Challenges Faced (and Solutions) • Evaluation • Testing • Demo

  3. Rise in Smartphone Sales • Sale of smartphones has overtaken personal computers in the year 2010 Source: International Data Corporation

  4. Rise Of Social Proximity apps • Applications where users discover others nearby and interact with them As of: 2nd November 2013

  5. Rise of Social Proximity Apps Market for social proximity apps Projected Growth: $1.9 billion Millions of dollars

  6. Social Proximity AppsImplementation • Location (typically GPS) datauploaded to a central server • Server determines who/what is nearby • Client downloads the list of neighbors • Client displays the neighbors to the user

  7. Problems • Battery consumption: Use of 3G + GPS is heavy on battery • Server-Reliance: Fails to function in absence of internet connectivity • Bandwidth consumption: 3G consume user’s data bandwidth • Network congestion: Cell towers are overloaded with small packets in network

  8. The FLITBY Application • Build a Facebook-like application that is server-less • Works without internet connectivity • Use peer-to-peer communication in order to exchange social data • Saves battery by eliminating 3G and GPS usage • Vision: people flit by one another and spontaneously sharing social data using the application, therefore it is called Flitby

  9. P2P Communication • Phone-to-phone communications such as Wifi-Directand Bluetooth • Proximity is inherent – if I can contact you, you must be nearby • Shortcoming: only support one-hop transfers which is very limited • Solution: Use Mobile Delay-Tolerant Network (DTN)

  10. MOBILE DELAY-TOlerant Network • Network of all mobile users • Topology changes rapidly because of high user mobility • Users exchange data when they are within range of one another • These connections are intermittent and short-lived in nature • No direct paths may exist between any two nodes • Messages are stored and forwarded opportunistically for multi-hop communication A B C

  11. Example OF HOW FLITBY WORKS Functionality #2: Propagate social data Functionality #1: Post a status Guys! Free ice cream sandwich here at the Ice Cream Store!

  12. Example OF HOW FLITBY WORKS Functionality #4: View status post associated with encounter Functionality #3: Log encounters with other users Functionality #5: Make comments and like them! Oh my god! Really?

  13. Challenge #1 • State Inconsistencies • In a decentralized network, it takes time for social data to propagate through the network • Therefore, it is usually the case that clients have a subset of the global state and this can be inconsistent. • Merging of subsets during chance encounters can warp the meaning of messages

  14. Challenge #1 Most recent first B T D J

  15. Challenge #1 B T D J

  16. Challenge #1 B T D J

  17. Challenge #1 B T D J

  18. Challenge #1 B T D J

  19. Challenge #1 B T D J

  20. Challenge #1 B T D J

  21. Challenge #1 The problem is that we did not capture the context of the comments!

  22. Challenge #1 • Solution • Present information in a coherent manner to the user • Tapping on a particular comment should show the context in which that comment was made

  23. Challenge #1

  24. Challenge #1

  25. Challenge #1

  26. Challenge #1

  27. Challenge #2 • Communication Challenges • Exchange of information relies upon often brief contacts with other users • Not enough time to exchange all data • Social network data is monotonically increasing • Infeasible to exchange all data with users

  28. Challenge #2 • Solution • Given that connection time is short-lived • Exchange of information should be prioritized based on one’s interest (friends or otherwise) • Reduce redundancy and only send new informationin form of deltas • Any connection/encounters with any other clients is purely opportunistic • Spread other non-priority data once priority data is exchanged • Mobility patterns of users may also be used to prioritize exchanges but this topic itself is its own research topic

  29. Challenge #2 Priority Data Non-priority Data

  30. Challenge #3 • Facebook Synchronization • Good idea to synchronize social networking data back to Facebook periodically • However, Facebook doesn’t allow arbitrary timestamps on status/comment posts. • It is difficult to coordinate the clients to preserve the order of comments

  31. Challenge #3 Solution: Use a proxy server to store social networking data from clients and commit to Facebook periodically. (Unimplemented)

  32. Challenge #4 • Privacy • Flitbyuses opportunistic routing through intermediate nodes • Intermediate nodes can access other people’s data • Negotiating cryptographic keys is difficult due to large delay. • Solution • Use a server to negotiate/distribute cryptographic keys. (Unimplemented)

  33. FlitbyArchitecture

  34. Database • User Table • Group Table • Status Table • Comment Table • Encounter Table

  35. Evaluation • Devices used: • Samsung Galaxy SII (v4.3.1) • Samsung Galaxy SIII (v4.1.2) • Nexus 4 (v4.3) • Wi-Fi used: • IEEE 802.11g • Development Environment: • Android Developer Tools v22.0.5-757759

  36. Evaluation • Time taken for DTN messages of varying sizes to be sent from node to node. (Using TCP over Wi-Fi)

  37. Evaluation • Throughput of DTN based on previous data • For comparison: In the US, 3G has a data bandwidth of 3.84Mbps/1.44Mbps (practical download/upload rate)

  38. Evaluation • Using Samsung Galaxy S2 and 3G network • 10 trials were conducted • Time recorded was time taken for the first screen to completely load

  39. Testing • Android Strict Mode • option in the application that would detect & log undesirable practices • Manual Testing • 1 phone test case • 2 phones test case • Systems Testing

  40. What Flitby Looks Like This is your profile information These are the people you have encountered with

  41. What Flitby Looks Like This is your profile information Type in a new status here

  42. What Flitby Looks Like Status Post Owner Status Post Write a response here Comments

  43. Demo

  44. Conclusion • We were able to develop Flitby as a decentralized social application that functions with DTN • We tackled 2 of the problems presented in this presentation • Communication Challenges (Application Routing Protocol) • State Inconsistencies (View Hierarchy) • Future work could involve: • Expanding the social network feature sets • Improving Privacy • Synchronization of social data back to Facebook

  45. End • Thank you for your attention! • Questions?

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