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Analysis of VoD System

Analysis of VoD System. Performance Evaluation Final Project Presentation, Fall 2007 Instructor: Prof. Dipak Ghosal. Prantik Bhattacharyya Avishek Nag pbhattacharyya@ucdavis.edu anag@ucdavis.edu University of California, Davis Davis - 95616. Outline. Definition of VoD System Demands

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Analysis of VoD System

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  1. Analysis of VoD System Performance Evaluation Final Project Presentation, Fall 2007 Instructor: Prof. Dipak Ghosal Prantik Bhattacharyya Avishek Nag pbhattacharyya@ucdavis.eduanag@ucdavis.edu University of California, Davis Davis - 95616

  2. Outline • Definition of VoD • System Demands • System Features • Problem Definition • Reliability • Possible Protocol • Possible Solution • Observation

  3. Definition of VoD • Video on Demand • Interactive entertainment • Control in subscriber's hands

  4. System Demands • Large Bandwidth Demand • Assured Quality of Service (QoS)‏ • Low Transmission Time • Low Packet Drop Rate • Large Buffer

  5. System Features • Large Number of Customers • Dedicated Transmission Line during Content Delivery • Infinite Buffer Length at Server side to retain Customer Request • Poisson Arrival of User Requests • Finite Source & Finite Buffer Model

  6. Problem Definition For a finite number of customers requesting video at a poisson arrival rate, if we have m servers what is the mathematical model which combines these parameters? User Requests Queuing Up m Servers n Users

  7. Reliability Packets will be lost during transmission

  8. Possible Protocol Features Required: 1. Acknowledgment of received packets 2. Congestion control 3. Retransmission of lost packets 4. Overbuffering (Faster than real-time streaming)‏ • RUDP : Reliable User Datagram Protocol • Provides a solution where other protocols are either too primitive or too complex

  9. Solution • The given problem can be modeled as M/M/m//n(n>m) queue with finite input source. • If n>m, i.e. population size> no. of servers a request have to wait when all the m servers are busy.

  10. Waiting Time Distribution • The waiting time distribution of the system can be written as, • The mean waiting time which is an important system parameter, can be obtained by evaluating the expectation. • Waiting time is dependent on the service time ; so system waiting time depends on the length of the video to be downloaded.

  11. Observation • Performance improvement can be obtained by dividing the entire video into small chunks and downloading them. • We can evaluate performance measures such as • optimal number of servers required for a given set of users. • the maximum length of time where all servers are busy. • Time congestion

  12. Reference: • Vilas, M.; Paneda, X.G.; Garcia, R.; Melendi, D.; Garcia, V.G.,User behavior analysis of a video-on-demand service with a wide variety of subjects and lengths, 31st EUROMICRO Conference on Software Engineering and Advanced Applications, 2005 • Reliable UDP – RUDP http://www.codeplex.com/RUDP • Wikipedia, RUDP, http://en.wikipedia.org/wiki/Reliable_User_Datagram_Protocol • Frederic Thouin and Mark Coates, Video-on-Demand Networks: Design Approaches and Future Challenges, IEEE Network Vol 21 March-April 2007 Page(s): 42-48 • Medhi, Stochastic Models in Queuing Theory,2nd Edition, Academic Press.

  13. Thank You! Questions?

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