Bandwidth Control in Multiple Video Windows

1
Bandwidth Control in Multiple Video Windows
Conferencing System
Fukuoka , Japan 23 January 2003
Present by Lee Hooi Sien
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