1 / 29

Statistical Modeling and Analysis of P2P Replication to Support Vod Service

Statistical Modeling and Analysis of P2P Replication to Support Vod Service. zyp. Infocom, 2011, Shanghai. Background. VoD: Video-on-Demand http://www.xunlei.com/ http://movie.youku.com/ Traditional VoD and P2P VoD First one,client-server approach Second one,P2P assisted VoD. Outline.

lotte
Download Presentation

Statistical Modeling and Analysis of P2P Replication to Support Vod Service

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Statistical Modeling and Analysis of P2P Replication to Support Vod Service zyp Infocom, 2011, Shanghai

  2. Background • VoD: Video-on-Demand • http://www.xunlei.com/ • http://movie.youku.com/ • Traditional VoD and P2P VoD • First one,client-server approach • Second one,P2P assisted VoD

  3. Outline • Introduction • Model • Replication algorithm • Analysis • Adaptive Algorithm • Simulation • Conclusion

  4. Introduction • P2P VoD • Storage to replicate content • Upload bandwidth • P2P replication is a central design issue in P2P VoD system

  5. Model • For a P2P VoD system • Average server bandwidth utilization(B) • Average number of movie copies(M) • Peers(N),movies(K) • Each peer: • Upload capacity(Ui) • movies stored(L) • movie set stored on peer i(Qi) • average requests received by peer i(λi) • Each movie: • relative popularity of movie j(ηj) • peer set replicating movie j(Sj)

  6. Model • Assumed: • movies are of the same size • have the same playback rate equal to 1(same as the average upload capacity) • Perfect Fair-Sharing Model • How a peer select a movie: • Deterministic Demand • Stationary(random)

  7. Model • Stationary(random): • transition matrix -> stationary state • in stationary state,any peer watch movie j is a Binomial distribution with ηj • average number requests for peer i • Objective of the P2P VoD system • This paper try to do: minimize B

  8. Replication Algorithm • Random with Load Balancing Assignment • for j=1 to K do • Bj=0 • end for • for i=1 to N do • Peer i randomly select L movies from the movie set and puts the id of each movie into Qi; • for do • Bj=Bj+Ui/λi,for homogeneous,Ui=1 • if Bj≥1 then • Never select movie j any more • end if • end for • end for

  9. Replication Algorithm • In this algorithm Bj meaning the expected received bandwidth for peers watching movie j. • For Homogeneous peer,their uplink capacity U=1. • This algorithm wants to make the most movie's B≥1

  10. Analysis Stationary Demand and Homogeneous(同类的) Peers • Requests at any peer i is a random variable of Binomial distribution( ) • For large N: • Bandwidth form provider i allocated to a peer watching movie j( ) • EQ.1

  11. Analysis • EQ.1:

  12. Analysis • Aggregate bandwidth that peers watching movie j get from other peers: • We need variance of Xj to describe B: • EQ.2

  13. Analysis • Weighted average variance of all movies: • EQ.3 • Constraints to restrict the allocation: • EQ.4 • EQ.5 • The RLB algorithm satisfying both conditions.

  14. Analysis • EQ.5: • Each peer stores exactly L movies,means 1/λi appears exactly L times.

  15. Analysis • The performance of RLB algorithm is given by EQ.3 • Correlation rj(i,k) is complicating factor. • rj(i,k)=1 • EQ.3 becomes EQ.6 • rj(i,k)=0 • EQ.3 becomes EQ.7

  16. Analysis • EQ.6: • rj(i,k)=1,means peers who store movie j have the same movie set,then λi=λk. • From EQ.4 we can get |sj|=λi.

  17. Analysis • The sever load with eq.4 and eq.5: • EQ.8 • The worst case rj(i,k)=1 • EQ.9 • The best case rj(i,k)=0 • EQ.10

  18. Analysis • EQ.8:

  19. Analysis Stationary demand and heterogeneous peers • The upload capacity of peer i be Ui. • EQ.1 is rewritten as EQ.11: • Proposition 1:They share same lower bound • Proposition 2:They share same upper bound

  20. Adaptive Algorithm • RLB is a centralized algorithm. • ARLB is a distributed one • Do movie replication based on the watched movies. • ARLB algorithm: • x+=x if x>0,else 0. • GAP means weighted gap between Bj and required playback rate(1).

  21. Adaptive Algorithm • Step1-3:Check i's storage. • Step4-5:Check movie j's bandwidth . • Step7:Find out which movie to be replaced. • Step8-19:Calculate the GAP before and after replace • Step20-22:Decision.

  22. Simulation • A.Stationary demand and static replication assignment • Model validation under homogeneous settings: • Evenly distributed movie popularity(ηj=1/K). • Homogeneous peer uplink capacity(Ui=1). • Simulation duration 1500 timeslots,viewing duration [20,40]. • N=10000,each peer make independently selection. • K/L=50,keep the bounds unchanged.

  23. Simulation • Sever load decreases when L is increased. • Server load of RLB is strictly bounded. • L=1 achieved lower-bound. Fig.1

  24. Simulation • Sensitivity analysis on configuration parameters:

  25. Simulation • Fig.2 shows that all the six cases that RLB performs much better and RLB is strictly bounded. • (a) changing the popularity • (b) changing the peer uplink capacity • (c) changing N • (d) changing K • (e) changing L with N,K fixed • (f) changing L with K/L fixed

  26. Simulation • B.Evaluate adaptive replication algorithms • The simulation configuration parameters is similar to A. • Compare with four replacement algorithms. • Also, these simulations show that ARLB performs much better then others,and ARLB still bounded by upper- and lower-bounds.

  27. Simulation

  28. Conclusion • This paper propose a service model and a stationary statistical demand model for P2P VoD. • Design a replication algorithm(RLB) and give an adaptive version(ARLB). • Simulation

  29. Thank you!

More Related