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Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
Congestion Control and Adaptive Retransmission for Multimedia ...
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Congestion Control and Adaptive Retransmission for Multimedia ...

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  • 1. Congestion Control and Adaptive Retransmission for Multimedia Streaming over Wireless Networks Kamal Singh, Árpád Huszák, David Ros, César Viho and Jeney Gábor IRISA/INRIA, Rennes, France BUTE, Budapest, Hungary 1
  • 2. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 2
  • 3. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 3
  • 4. Overview: Next Generation Wireless Network “Hotspots” with high Video Streaming bandwidth anywhere in the cell Users of Voice, TCP, … 4
  • 5. Overview: Wireless Problems in the context of Video Streaming  Problems due to the use of IP  IP doesn’t support real time streaming requirements  Problems due to radio conditions  Scarce and time varying bandwidth  Congestion, wireless losses & large delay 5
  • 6. Overview: Video Streaming  Video Streaming constraints • Delay & Jitter • Bandwidth, Congestion • Packet loss 6
  • 7. Overview: Video Streaming …  Video Streaming • Underflow • No Playout • Packet losses will cause quality distortion 7
  • 8. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 8
  • 9. Congestion Control for Video Flows  Motivation • Variable bandwidth, delay … • Congestion, packet losses How can applications adapt to the network conditions? 9
  • 10. Existing Schemes  Congestion control for video  TCP: Retransmissions, rate oscillations, …  TFRC [Floyd 2000]  Sending Rate is calculated by a TCP model  Better Rate Stability  TCP Friendly 10
  • 11. Problems: Wireless Losses  Problem: Two types of losses in wireless Networks  Packet drops due to congestion  Packet drops due to bad channel conditions Wireless network IP Packets IP Queue Router Node B Wireless loss Congestion loss 11
  • 12. Problems …  Inefficiency for TCP, TFRC …  Cannot distinguish between these losses.  Reduce their sending rate on loss.  How to distinguish Wireless losses from congestion losses?  Previous Work have used Round Trip Time variations: May not be reliable  ARC [O. B. Akan et al. 04]: Sending Rate (S) is calculated using w : ,  ARC: How to calculate w ? 12
  • 13. Wireless Loss Estimation (Background: DiffServ)  Differential dropping in the DiffServ Assured Forwarding (Green, Yellow & Red) Increasing Congestion Drop Red Drop Red + Yellow Rarely drop Green packets packets packets  Video applications mark their packets I B P B P 13
  • 14. Wireless Loss Estimation  Wireless Loss Estimation in DiffServ (WLED) Networks: [VTC 2006]  Red packets are dropped first on congestion  Wireless loss rate (w) is correlated with green loss rate  If loss of yellow packets is not significant  Estimate w for ARC using green loss rate 14
  • 15. WLED  WLED: WLED Improves link utilization TFRC TCP  There is no change in other properties:  TCP friendliness, loss rate, rate stability  But, works only with DiffServ aware applications 15
  • 16. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 16
  • 17. Adaptive retransmissions and wireless loss estimation  We improved link utilization in case of wireless losses.  But, lost data still deteriorates the quality!  Solution: We integrate a scheme to retransmit the lost data. 17
  • 18. Adaptive retransmissions and wireless loss estimation …  Retransmission Scheme  If packet has the possibility to arrive before its deadline  No congestion  Enables retransmission schemes  Congestion  Disable retransmission  Example Scenario: 18
  • 19. Adaptive retransmissions and wireless loss estimation …  Depending on:  Available Bandwidth shown by Congestion Control scheme  Amount of I, P and B frames in video files  Retransmit either  I frames  I + P frames or  All frames  WLED scheme integrated 19
  • 20. Adaptive retransmissions and wireless loss estimation : Transport protocol  DCCP (Datagram Congestion Control Protocol)  Sequence numbers  Feedback/ACK vectors  Useful for loss detection  Retransmissions done at the application layer 20
  • 21. Adaptive retransmissions and wireless loss estimation : Simulation details  NS2  Dumbbell topology with 1Mbps of link with 40ms delay  Packet losses simulated in the wireless link  Reference Video: 360kbps “Mother and Daughter” encoded using H.264  FTP and WWW flows as background 21
  • 22. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 22
  • 23. Key Results • 10 WWW users in background 23
  • 24. Key Results … • Wireless loss probability 0.1 and varying WWW users 24
  • 25. Agenda  Overview  Congestion control for Video Flows  Adaptive retransmissions and wireless loss estimation  Results  Conclusion and Future Work 25
  • 26. Conclusion and Future Work  Used a wireless loss estimation scheme integrated with a retransmission scheme  Obtained better video quality  Future Work  Performance of WLED + retransmission in real network  Congestion control and adaptive retransmission for MPEG4-scalable video codec (SVC) 26
  • 27. Thank You ! 27

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