Elastic - DASH
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Transcript of Elastic - DASH
ELASTICClient Side Controller for DASH
Yigit UNALLAR
DESIGN DRAWBACKS:
• QoE,• On-off traffic pattern;
• Unfairness,• Underutilization of bottleneck,
PROPOSED SOLUTION:
• Feedback Linearization Adaptive Streaming Controller,
• Feedback Control Theory,• Controlled Testbed;
• BW cap. is set,• Delays are set.
COMPARISON CRITERIA:
• Fully bottleneck utilization,• Fair bottleneck share, • Fairly share w/ TCP Greedy flows.
INTRODUCTION:• Client-side Algorithms,
• On-off pattern at steady state,• Unfairness sharing a bottleneck,
• 3 Popular Services suffer,• Unable to get fair share w/ TCP Greedy Flow,
“Downward Spiral Effect”• Algorithm w/o on-off traffic pattern, “downward spiral
effect”, large player buffers and increased segment size proposed!
APPROACH:• ELASTIC proposed,• Performance comparison w/ Conventional, PANDA&
ELASTIC,• Many videos, same algorithm, same bottleneck,• Many videos, TCP greedy flow, same bottleneck,
RELATED WORK:
• Architecture;• Video segments of fixed duration τ ,
• Playout buffer full ➔Steady- state,• HTTP requests each τ sec. to maintain,
• On-off patterns occur during download& idle modes,
• 3 Commercial services suffer from unfair share due to on-off
traffic pattern!!
ELASTIC:
• Design Requirements:• Dynamically select video level l(t) to achieve QoE,• But what impairs QoE?
• Re-buffering when buffer gets empty,• Frequent quality switches,
• Video level w/ higher bitrate and quality desired!
ELASTIC:
• Design Goals:• Low re-buffering ratio,• High obtained video level,• Video level switches, • Fair sharing.
CONTROLLER:
• Conventional Approach;• Throttle l(t) to match the measured available b(t),• Control q(t) by regulating idle periods,
• However, Elastic proposes;• Throttle l(t) to drive q(t) to a set-point qT,
• No idle state btwn 2 downloads,
• q(t)➔qt , l(t) // b(t)
Employ feedback linearization to (1) and steer q(t) to qT, following dynamics imposed;
IMPLEMENTATION:
“Where kp=1/100,
ki=1/1000.”
TESTBED:
SCENARIOS& METRICS:• S1:• Video + TCP,• b = 4Mbps,• ”Dynamic behavior of algorithms.”
• S2:• Many Video + Many TCP,• b = 40Mbps,• “Comparing performances employing Table II metrics.”
SCENARIOS& METRICS:
RESULTS:• S1:
RESULTS:• S1: “TCP flow starts at t=100s.”
“As seen, ELASTIC does not produce an on-off traffic, thus behaving as a TCP flow!”
RESULTS:• S1:
RESULTS:• S2: “TCP flow starts at t=100s, for each N the fair share can be computed as
F=40Mbps/N.”
RESULTS:
• S2: NTCP=0,
RESULTS:
• S2: NTCP != 0,
RESULTS:
• S2: NTCP != 0,
RESULTS:
• S2: NTCP != 0, N<50 =>ratio < 1%
CONCLUSIONS:• Identical traffic pattern to any long-lived TCP flow accomplished.
• All algorithms performed well in the absence of TCP flows.
• in S2:• Fair share obtained,• Video continuously reproduced,• Video level switches mitigated.
THANK YOU…