Your SlideShare is downloading. ×
  • Like
PV Powerpoint
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.


Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply


  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads


Total Views
On SlideShare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. TCP Video Streaming to Bandwidth-Limited Access Links Puneet Mehra and Avideh Zakhor Video and Image Processing Lab University of California, Berkeley
  • 2. Talk Outline
    • Goals & Motivation
    • Our Approach
    • Experimental Results
    • Related Work
    • Conclusion
  • 3. Goal
    • Efficient video streaming using TCP to bandwidth-limited receivers
    • Key Assumptions:
      • Receivers have limited-bandwidth last mile connections to Internet
      • … and run multiple concurrent TCP networking apps
    • Constraints:
      • Should not modify senders or network infrastructure
  • 4. Motivation
    • Increasingly access links are the net. Bottleneck!
      • Limited Bandwidth (B/W)  Less than 1.5MBps
      • Users run concurrent apps  compete for limited B/W
    • Most Traffic on Internet is TCP [HTTP, P2P, FTP]
      • TCP handles recovery of lost packets
      • TCP has congestion control
      • UDP Streaming difficult w/ firewalls
    • Problem: TCP shares bottleneck B/W according to RTT
      • May Not provide enough B/W for streaming apps
  • 5. Example Situation High RTT Med. RTT Low RTT Congestion Most Bandwidth!
  • 6. Talk Outline
    • Motivation & Goals
    • Our Approach
    • Experimental Results
    • Related Work
    • Conclusion
  • 7. Our Approach
    • We developed a receiver-based bandwidth sharing system (BWSS) for TCP [INFOCOM 2003]
    • Key Idea: Break fairness among TCP flows to allow user-specified B/W allocation
    • Approach: Limit throughput of low-priority connections to provide B/W for high-priority ones
      • Ensures full utilization of access link
      • Doesn’t require changes to TCP/senders or infrastructure
  • 8. BWSS Overview
  • 9. Target Rate Allocation Subsystem
    • Some apps need minimum guaranteed rate(video), others don’t (ftp)
    • User assigns each flow:
      • Priority, minimum rate and weight
    • Bandwidth allocation algorithm:
      • Satisfy minimum rate in decreasing order of priority
      • Remaining B/W shared according to weight
    T 1 User Prefs. σ T n
  • 10. Flow Control System (FCS) w – TCP window RTT – Flow RTT MSS – TCP MSS
  • 11. σ – Calculation Subsystem
    • Goal: Choose σ to maximize link utilization. U = Σ i R i ( σ )
    • Approach: Use increase/decrease in measured throughput to guide increase/decrease of σ
    R 1 R N σ = Σ i T i T 1 = R 1 σ U W 2 W 1 Link Capacity T 2 = R 2 T 1 = R 1 T 2 ≠ R 2 T 2 = R 2
  • 12. Talk Outline
    • Motivation & Goals
    • Our Approach
    • Experimental Results
    • Related Work
    • Conclusion
  • 13. Experimental Setup RUDE
  • 14. Experimental Details Invisible to Apps User Level App  easy to deploy ETH0 NIST NET Emulator BW = 960 Kbps Delay = 30 ms BWSS – Shared Library APP_1 APP_n APP_2
  • 15. TCP vs BWSS Internet Experiments
    • Video streamed at 496Kbps
    • Congestion on access link from 30s to 60s
    • Standard TCP not good enough during congestion
  • 16. BWSS Reduces Required Pre-Buffering
    • BWSS provides 4X reduction in pre-buffering over standard TCP
  • 17. SureStream TM Experimental Setup RUDE
  • 18. RealVideo SureStream TM Internet Experiments
    • Takeaway: standard TCP not good enough for streaming
    • Video encoded at 450Kbps, 350Kbps, 260Kbps & 64Kbps
    • Congestion on access link from 60s to 100s (320Kbps)
    Despite congestion, video streams at steady rate. Poor streaming quality
  • 19. RealVideo SureStream TM Internet Experiments UDP TCP w/ BWSS
    • Takeaway: BWSS can break fairness among flows locally, and provide additional B/W for video apps.
    UDP SureStream unable to stream at 450KBps till after congestion Constant streaming at 450Kbps
  • 20. Related Work – TCP Streaming
    • Network-Based Approaches
      • Receiver-based Delay Control (RDC) [NOSSDAV 2001]
        • receivers delay ACK packets based on router feedback
        • Mimic a CBR connection
    • End-Host Approaches
      • Time-lined TCP (T-TCP) [ICNP 2002]
      • TCP Real-Time Mode (TCP-RTM) [ICNP 2002]
      • Must modify both sender & receiver to allow skipping “late” packets
  • 21. Conclusions
    • BWSS allows flexible allocation of link B/W
      • Breaks fairness among TCP flows “locally” in manner unavailable to TCP-Friendly UDP protocols
    • BWSS enables efficient video streaming over TCP to bandwidth-limited receivers
      • Better performance than standard TCP
      • In some cases, better performance than congestion-aware UDP
    • Future Work: Incorporating UDP flows
  • 22. Questions?