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  1. 1. INFOCOM, 2007 Chen Bin Kuo (20077202) Young J. Won (20063292) DPNM Lab.
  2. 2. <ul><li>Introduction </li></ul><ul><li>Problem Description and Assumptions </li></ul><ul><li>Mathematical Model </li></ul><ul><li>Simulation Result </li></ul><ul><li>Conclusions </li></ul><ul><li>Discussion </li></ul>05/19/10
  3. 3. <ul><li>Fiber optic access networks (fiber-to-the-premises and fiber-to-the-node) have boosted individual user’s broadband access speeds. </li></ul><ul><li>IP networks may soon become a delivery mechanism for broadcast television content. </li></ul>05/19/10
  4. 4. <ul><li>IP data packets in FTTP network might include: </li></ul><ul><ul><li>Broadcast video </li></ul></ul><ul><ul><li>Video-on-demand (VOD) </li></ul></ul><ul><ul><li>Web applications such as web surfing, online gaming, and p2p file transfers </li></ul></ul><ul><li>Demand of a video stream (under MPEG-2 encoding) </li></ul><ul><ul><li>Standard definition (SD) : 3.75 Mbps </li></ul></ul><ul><ul><li>High definition (HD) : 15 Mbps </li></ul></ul><ul><li>Evaluating bandwidth demand is necessary. </li></ul>05/19/10
  5. 5. 05/19/10 Portion of a FTTP network How big do these links need to be? Core router and edge router deliver content to the edge of the network . An OTL forwards the content over a PON to an ONT at each subscriber’s premise. 32 subscribers 2000 subscribers Core Router Edge Router Optical Line Terminal (OLT) Passive Optical Network (PON) Optical Network Terminal (ONT)
  6. 6. <ul><li>Steady state demand </li></ul><ul><ul><li>Analytical methods for engineering links often assume stationary (steady state) busy hour traffic. </li></ul></ul><ul><ul><li>All viewers have settled into channels </li></ul></ul><ul><ul><li>Using multicast to satisfy demand </li></ul></ul><ul><li>Channel surfing </li></ul><ul><ul><li>Disrupting the steady state at every commercial break </li></ul></ul><ul><ul><li>Significant additional bandwidth demand is required. </li></ul></ul>05/19/10
  7. 7. If there exist two viewers watch the same channel (5 different in total) 05/19/10 If all viewers watch different channels (6 different channels) 6 video stream required 5 video stream required Viewers OTL Edge Router The network needs to deliver only one video stream for the same channel to the OLT where it must divide the stream for two viewers.
  8. 8. <ul><li>The way to make channel changes fast is to send surfers unicast (one per viewer) streams at higher rates. </li></ul>05/19/10 Channel change server Playout buffer (in the set top box) Higher rate Usual rate
  9. 9. 05/19/10 Settled in one channel (steady state) Channel surfing (commercial break) Bandwidth Time <ul><li>Bandwidth planning issue </li></ul><ul><li>What is the demand? </li></ul><ul><li>How to model the traffic? </li></ul>
  10. 10. <ul><li>A viewer: a device capable of receiving an IPTV stream </li></ul><ul><li>Each set top box always remains on and receives some video stream </li></ul><ul><li>This paper only to characterize broadcast IP TV’s contribution (from edge router to an OLT) </li></ul><ul><li>Homogeneous viewers </li></ul>05/19/10
  11. 11. <ul><li>The program definition is independent of the renewal process </li></ul><ul><li>The number of active viewers is constant during commercial break </li></ul><ul><li>Commercial breaks on all channels begin at the same time and all active viewers begin surfing at the same time </li></ul>05/19/10
  12. 12. 05/19/10 Steady State Multicast Model Channel Surfing Model – Single User Extend to multiple users Focusing on the viewers who are not surfing The Time to Fill the Playout Buffer Single Viewer Behavior Combined Model (Multiple Users) Bandwidth Demand
  13. 13. 05/19/10 Channel i , probability that a viewer will choose
  14. 14. 05/19/10
  15. 15. 05/19/10 The time the bandwidth must stay high after a single channel change A random variable, which is the bandwidth demand of a viewer at time t
  16. 16. 05/19/10
  17. 17. 05/19/10
  18. 18. 05/19/10 The time to start channel surfing when commercial break starts The channel surfing ends
  19. 19. <ul><li>The paper developed a model to quantify bandwidth demand during the transition from surfing to steady state viewing. </li></ul><ul><li>The example with 400 viewers shows mean demand during surfing peaking at almost two times the steady state level if the service provider offers fast IP TV channel changes. </li></ul>05/19/10
  20. 20. <ul><li>Assumptions of the mathematical model </li></ul><ul><li>How to model the user behavior more realistic? </li></ul><ul><li>What else can we contribute to the IP TV filed? </li></ul>05/19/10