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ON DESIGING END-USER MULTICAST FOR MULTIPLE VIDEO SOURCES

ON DESIGING END-USER MULTICAST FOR MULTIPLE VIDEO SOURCES. Y.Nakamura, H.Yamaguchi, A.Hiromori, K.Yasumoto † , T.Higashino and K.Taniguchi Osaka University † Nara Institute of Science and Technology. Goal. Realizing Multi-party video conferencing systems

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ON DESIGING END-USER MULTICAST FOR MULTIPLE VIDEO SOURCES

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  1. ON DESIGING END-USER MULTICAST FOR MULTIPLE VIDEO SOURCES Y.Nakamura, H.Yamaguchi, A.Hiromori, K.Yasumoto†, T.Higashino and K.Taniguchi Osaka University †Nara Institute of Science and Technology

  2. Goal • Realizing Multi-party video conferencing systems • Many-to-many multicast application which consists of hundreds of users • User hosts exchange multiple video streams in real-time • Efficient use of bandwidth is required Internet ICME2003

  3. Application Layer Multicast (ALM) • ALM is multicast on overlay networks • End users act as multicast routers • Does not require special hardware such as IP multicast enable routers • Application-specific routing protocols can be designed • More efficient than Unicast because a sender does not need to send data to all receivers Unicast ALM A A B S B S C C D D ICME2003

  4. Design Issues • Each video uses some amount of bandwidth on overlay networks →In delivering multiple video streams, they compete for bandwidth on overlay links • Users may have priority requirements to video streams e.g. users may prefer the speaker’s video than audience’s Internet ICME2003

  5. Internet Overlay Network End-user Multicast for Multi-party Application (Emma) • New ALM protocol for multi-party communication systems • Users construct overlay networks • Each user host sends its own video continuously and receives some of other user hosts’ video streams on overlay networks • The sending and receiving video streams are controlled based on users’ priority requirement given to the video streams Red Red ICME2003

  6. Users’ Join • When a new user wants to join a session, the user gets the current users’ addresses from a central server • The user measures delay with these users and establish overlay links with the closest two or three users to construct mesh-like overlay networks • Existing routing trees are expanded so that they do not overlap each other as long as they can E C A • Routing tree can be expanded with • small delay from each source • less duplication A:133.1.xx.xx B:129.3.yy.yy C: … Address Management Server D B ICME2003

  7. Priority-based Video Delivery • Each user specifies a priority requirement as a priority value to each video stream. • A request message with a priority value is forwarded to the video source user • But there is no enough bandwidth on the path C A A: 8 B: 5 C: 6 D:15 D B ICME2003

  8. Priority-based Video Delivery • In forwarding the message, the followings are calculated step by step • how to stop existing video streams • how to minimize the loss of priority values • If the loss of priority value < the gain of priority value by accepting the request • The existing streams are stopped and the new stream is delivered C A A: 8 The sum of the satisfied priority values becomes larger than before B: 5 C: 6 D:15 D B ICME2003

  9. E Users’ Leave and Failure • Even if an user host leaves, trees can be recovered • When a user leaves, the simplest way to recover tree is to let child nodes connect with the parent of the leaving user • However, this may cause the concentration of overlay links to the parent user • To prevent this, each user periodically collects the information of # of overlay links of its descendant users • When a user leaves, its parent can immediately suggest the children of the leaving user where to connect again D,F,G C,D G C A User E leaves Recovery can be done quickly without causing unbalanced trees H F D B ICME2003

  10. Performance Evaluation • We have developed a simulator for evaluating performance of Emma • Written in an object oriented scripting language Ruby • Network model • Hierarchical topology model based on tiers • 146 nodes, 66 users • Users give priority values to video by Zipf’s law ICME2003

  11. Users’ Satisfaction • The variation of average of satisfied priority value per user • Compared with First-Come-First-Serve (FCFS) method which accepts user requests in a greedy manner • Simulation Scenario • Until 5 units of time, 66 users joined • After 21 units of time, 1 user joins or leaves at one time ICME2003

  12. Users’ Satisfaction • Emma achieves 1.5 times higher values than FCFS • Under the presence of users’ leave and join, priority values are kept high ICME2003

  13. Routing Tree Duplication on Overlay Link • # of routing trees on an overlay link • Less duplication is desirable • Simple estimation of average duplication in the ideal case • # of users × (# of users -1) / # of total overlay links = about 20 →Measure the # of routing trees on each overlay link ICME2003

  14. Routing Tree Duplication on Overlay Link • 80% of overlay links have at most 10 routing trees ICME2003

  15. Conclusion • We have proposed new ALM protocol called Emma • Avoiding resource competition • From the experimental results • Higher satisfaction of users than a simple method • Even though some users leave from or join to a session, users’ satisfaction is kept high • We have designed and implemented Java middleware based on Emma (http://www-tani.ist.osaka-u.ac.jp/software/s2.html) ICME2003

  16. ICME2003

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