A Peer-to-Peer Approach for Mobile File Transfer in Opportunistic People Networks

1. A Peer-to-Peer Approach for Mobile File Transfer in Opportunistic People Networks Ling-Jyh Chen and Ting-Kai Huang Institute of Information Science, Academia Sinica, Taiwan

2. Motivation • Internet is part of our lives • We can use the Internet “almost” anywhere/ anytime. • Cellular • Wi-Fi Hotspots • Even with Mobility, we have handover solutions.

3. What will happen when the Internet is not always available?

4. Previous Solutions • Infostation-based approaches • Mobile Hotspots [19] • Ott ’06 [27] • But, • Dedicated Infostations needed • Single point of failure and scalability problems

5. Our Contribution • We proposed M-FTP to improve the effectiveness of FTP application in mobile opportunistic networks. • Every peer can access the Internet when parts of them have internet access. • Proposed a “Collaborative Forwarding algorithm” to further utilize opportunistic ad hoc connections and spare storage in the network.

6. Our Assumption • All peers are collaborative. • All peers have local connectivity • WiFi, Bluetooth, etc. • All peers are mobile. • Some peers have Internet access.

7. FTP M-FTP: Scenario 1 Internet Gateway Peer: A peer who can access the Internet directly

8. M-FTP : Scenario 2a Gateway Peer (B) Vanilla Peer (A): Peer that cannot access Internet directly

9. M-FTP : Scenario 2b Vanilla Peer (A) Vanilla Peer (B)

10. Y N Y N Y N N N Y B rcv A’s request B is a GP B and A are connected B has the Requested file Direct forwarding The request has been relayed H times B and A are connected Collaborative forwarding Y Indirect Forwarding Do nothing Request Forwarding

11. Collaborative Forwarding Algorithm • Goal: Increase the packet delivery ratio and decrease the request response time • Method: • PROPHET [22] • Based on Epidemic Routing Scheme [26] • Delivery predictability • Caching improves hit rate in the future (esp. for popular pages).

12. Direct Forwarding vs. Indirect Forwarding • B has complete content =>Direct Forwarding algorithm • B may only have partial content =>Indirect Forwarding algorithm • Further passing the request message using Request Forwardingalgorithm

13. Evaluations • Evaluate the performance of M-FTP scheme against Mobile Hotspots scheme • Service ratio and traffic overhead • DTNSIM: Java-based simulator • Real-world wireless traces • UCSD (campus trace) • iMote (Infocom ‘05)

14. The Properties of two network traces

15. Parameter Settings • Number of GPs • γ mobile peers • Number of requesters: • 20% of the other peers (VPs) • Number of requests: • first 10% of simulation time with a Poisson rate of 1800 sec/request. • The FTP requests: • top 100 requested iTunes songs , • As report as in iTune store on Sep. 7 2007.

16. UCSD scenario γ= 20% γ= 60%

17. iMote scenario γ= 20% γ= 60%

18. Traffic Overhead

19. Conclusion • We propose the solution, M-FTP, that can provide effective data transfer on the go. • Peer to peer • No dedicated devices • M-FTP implements a Collaborative Forwardingalgorithm that takes advantage of opportunistic encounters.

20. Thank You!