Chun-Yuan Chang, Cheng-Fu Chou * and Ming-Hung Chen Presenter: Prof. Cheng-Fu Chou

1. Striking The Balance Between Content Diversity and Content Importance in Swarm-Based P2P Streaming System Chun-Yuan Chang, Cheng-Fu Chou* and Ming-Hung Chen Presenter: Prof. Cheng-Fu Chou National Taiwan University ccf@cmlab.csie.ntu.edu.tw

2. Outline Introduction Model & Chunk Selection Strategies Practical P2P Streaming System & Dynamic Strategy-Switch Performance Evaluation Conclusion

3. Introduction • Swarm-Based P2P Streaming • Similar to “BitTorrent” • Encourage users to contribute its outbound bandwidth and storage to speed up content distribution. • PPLive, PPStream, CoolStreaming and GridMedia, etc

4. Introduction The chunk IDs the peer possesses • Two components • Overlay construction • Chunk swarming mechanism • Buffer map exchange • Chunk scheduling

5. Introduction No content to exchange even if outbound bandwidth is sufficient More diverse the content distribution is made, the less the content bottleneck is !! Content bottleneck problem

6. Introduction • Existing approaches • Rarest-First • E.g. CoolStreamingInfocom 2005 • Random • E.g. Chainsaw Infocom 2005 • Hybrid ones (Deadline-First + Rarest-First) • E.g.BitosInfocom 2006 and PrimeInfocom 2007 • Network Coding • E.g. R2 JASC 2007

7. Introduction • System dynamics • Peer churn • Network core congestion • Variable source streaming rate • Content diversity • Random chunk loss • Content Importance • Unequal content importance

8. Introduction With and without considering content importance

9. Outline Introduction Model & Chunk Selection Strategies Practical P2P Streaming System & Dynamic Strategy-Switch Performance Evaluation Conclusion

10. Model & Chunk Selection Strategies Simple Model (ICNP 2007)

11. Model & Chunk Selection Strategies • Recursive Formulation

12. Rarest-First(RF) • Priority B(1)>B(2).. therefore

13. Importance-First(IF) • ch>cl • Rarity is adopted to do a tie-break

14. Importance-First(IF) Only ch can compete to each other

15. Importance-First(IF)

16. Numerical Result(1)

17. Numerical Result(2)

18. Simulation Result

19. Short Discussion How canwe support high scheduling Efficiencyand maintain the scalability at the same time?

20. Insights When population size is not large, we can enjoy throughput and scheduling efficiency simultaneously There exist a good balance between content diversity and content importance

21. Outline Introduction Model & Chunk Selection Strategies Practical P2P Streaming System & Dynamic Strategy-Switch Performance Evaluation Conclusion

22. Practical P2P Streaming System Receiver Side

23. Practical P2P Streaming System Supplier Side

24. Dynamic Strategy-Switch • As a receiver: • Detect if the number of retrieval chunks in the request window is zero. If it does, send a signal to itself. No scheduling process will be performed. • If it does not , just subscribe to all desired chunks and assign each desired chunk to a peer who possesses the chunk in a random fashion • As a sender: • Check if the event of content bottleneck is captured. If it does, conduct RAND on each requested packet. Otherwise, conduct IF on each requested packet.

25. Outline Introduction Model & Chunk Selection Strategies Practical P2P Streaming System & Dynamic Strategy-Switch Performance Evaluation Conclusion

26. Performance Evaluation • Simulator • GridMediaProject • Settings:

27. Performance Evaluation • Video Trace: • Encoded by H.264 (JM16.0) • Concatenated by different types of CIF video sequences, which include high motion and low motion video sequences • Fixed the quantization parameters (QP) for I,P,B frame in encoding

28. Metrics • Delivery Ratio: • the ratio of the number of chunks that arrive before playback deadline to the number of chunks that should arrive before playback deadline. • PSNR (dB): • the rendered video quality compared with the raw video sequence. The ffmpegis used as our decoder.

29. Comparisons • RAND: • peers always serve the chunk in random fashion • IF-IPB: • peers always serve the chunk with highest priority with respect to –IPB. • PR-IPB: • the prioritized random scheduling in [10] • UL-IPB: • the utility-like approach in [15]

30. Comparisons Scalability

31. Comparisons Scheduling Efficiency

32. Comparisons underload overload PSNR over time with 4,500 peers

33. Conclusion Point out the trade-off between content diversity and content importance A simple but effective content bottleneck detector is proposed to strike the balance between content diversity and content importance