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  • 1. Bandwidth Control in Multiple Video Windows’ Conferencing System Present by : Lee Hooi Sien Fukuoka , Japan 23 January 2003
  • 2. Benefits
    • Communicate with multiple parties at the same time
    • Improve Productivity
    • Allow boardroom conferencing
  • 3. Network Protocol
  • 4. Drawbacks
    • Control Complexity Increase
    • Bandwidth problem
      • Congestion occurs
      • Packet loss
      • Severe drop in video quality.
  • 5. Solving Methods
    • Multicast
    • Rate Control
    • Preemptive Bandwidth Allocation
  • 6. Multicast
    • Assign group IP addresses to groups of users
    • Information just need to be sent once to the group IP address
    • Uses network resources and bandwidth more efficiently
  • 7. Rate Control
    • Two Main functions
      • Estimate the available bandwidth
      • Match video rate to available bandwidth
    • Can be performed at :
      • Sender
      • Receiver
  • 8. Rate Control - Source
    • Source explicitly adapts the video rate.
    • Feedback from the receiver is used to estimate the available bandwidth – Packet loss rate.
    • Methods for estimating bandwidth
      • Probe-based method
  • 9. Rate Control - Receiver
    • Selects the video rate from a number of possible rates.
    • Method used : Receiver Driven Layered Multicast
      • Sender codes video with scalable or layered coder
      • Sends different layers over different multicast groups
      • Receives an appropriate number of layers up to its available bandwidth.
  • 10. Rate Control - Receiver
    • Need modification – Not suitable for multiple data streams transmission.
    • Proposed method – Based on Receiver-based Layered Multicast (RLM)
    • Utilize priority information on the video quality
    • Specify which video stream should be received with high quality
    • Others received with the lowest quality
    • Only allow adjustment for high priority video stream
  • 11. Preemptive Bandwidth Allocation
    • Flexibly decreased or increased according to the congestion of networks .
    • Main function – preempt bandwidth
    • Condition – Shared-based multicast tree
    • Involve 2 admission controls
  • 12. Admission Control
    • First Admission Control
      • Check available bandwidth
      • Satisfied??
      • If not, proceed to second admission control
    • Second Admission Control
      • Check if any possible bandwidth preemption
      • If succeed, calculate amount of preemptable bandwidth has to release
  • 13. Conclusion
    • Bandwidth control is important in conferencing system because :-
      • Video packets require higher bandwidth
      • Multiple video stream
      • Complexity in controlling the streams
  • 14. Thank You