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A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
A7-2.ppt
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A7-2.ppt

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Transcript

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

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