Transcript Adaptive Video Streaming in Vertical Handoff: A Case Study

Adaptive Video Streaming in
Vertical Handoff: A Case Study
Ling-Jyh Chen, Guang Yang, Tony Sun, M. Y. Sanadidi, Mario Gerla
Computer Science Department, University of California at Los Angeles
Adaptive Video Streaming in Vertical Handoff: A Case Study
Outline of the Talk
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The problem: the performance of video
streaming may degrade due to wireless channel
errors and vertical handoffs.
Key idea:
 Adaptive
video delivery can improve the end user’s
perceived quality.
 Seamless handoff can provide uninterrupted services
even with the presence of mobility.
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The results: we show that the combination of
adaptive video streaming and seamless handoff
can go a long way in providing better video
streaming in mobile computing scenarios.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Introduction
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Mobile Computing Scenarios
Mobility
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Introduction (cont.)
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Three issues:
Seamless mobility across heterogeneous
networks.
2. Adaptation to network dynamics such as
wireless channel errors and congestion.
3. Application adaptation to maximize the end
user’s perceived quality.
1.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Background – Seamless Handoff
A seamless handoff is defined as a handoff scheme that
maintains the connectivity of all applications on the mobile
device when the handoff occurs.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Background – Seamless Handoff
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Two goals: low latencies and few packet losses
Related Work
 Network
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 Upper
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Layer Approaches
MIPv4, IPv6
Layer Approaches
End-to-End Approaches (e.g. Dynamic DNS)
New Session Layer Protocols (e.g. MSOCKS)
Transport Layer Protocols (e.g. TCP-MH and SCTP)
Middleware Approach (e.g. USHA)
Q: Which seamless handoff solution are you using?
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Proposed Approach: USHA
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Universal Seamless Handoff Architecture
NAT server
NAT Server
All packets are encapsulated
and transmitted using UDP
Applications are bound to the tunnel
and transparent to the handoff.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Background – Video Streaming
Best-effort streaming
Real-time streaming
adapt sending rate
adapt sending rate and stream quality
SCP
Helix
RAP
TEAR
Microsoft
VTP
TFRC
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Proposed Approach: VTP
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1.
Video Transport Protocol
Bandwidth Estimation
Achieved Rate Measurement:
k 1
bj 
d
l 0
j l
t j  t j ( k 1)
 b j  b j 1 

Available Bandwidth Estimation: B j    B j 1  (1   )
2
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
Assume we use packet trains of length k to measure the achieved rate.
Denote di as the number of bytes in packet i, ti as the time when packet i arrives at the client.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Proposed Approach: VTP (cont.)
2.
Rate Adaptation: Multiple streams of the same
content are encoded at different rates.
DR: Decreasing Rate State
IR: Increasing Rate State
Q0: Lowest Quality Video (56Kbps)
Q1: Normal Quality Video (150Kbps)
Q2: Highest Quality Video (500Kbps)
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Proposed Approach: VTP (cont.)
3.
Variable Bit Rate (VBR) Video
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VTP divides a video clip into a number of segments.
For each segment, VTP computes a target rate, at
which neither buffer overrun or underrun should
occur.
Since video streams are pre-stored, instantaneous
sending rates are available beforehand, and so are
the target rates of the segments.
VTP applies these target rates to the finite state
machine for rate adaptation.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Experiments
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VTP server/client are implemented on Linux.
USHA system is set up on Linux, with custom
configured NAT and IP tunneling.
VTP client is connected to the Internet via
802.11b and 1xRTT, which is provided by
Verizon Wireless.
Two vertical handoff scenarios are tested:
1.
2.
From 1xRTT to 802.11b
From 802.11b to 1xRTT
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Experiments: 1xRTT to 802.11b
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Non-adaptive Video Streaming
Frame Rate received at the Mobile Host
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Sending Rate at the Video Server
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Experiments: 1xRTT to 802.11b
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Adaptive Video Streaming
Video
FrameQuality
Rate received
sent at the
at the
Video
Mobile
Server
Host
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Sending Rate at the Video Server
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Experiments: 802.11b to 1xRTT
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Non-adaptive Video Streaming
Frame Rate received at the Mobile Host
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Sending Rate at the Video Server
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Experiments: 802.11b to 1xRTT
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Adaptive Video Streaming
Frame
VideoRate
Quality
received
sent at
at the
the Video
MobileServer
Host
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Sending Rate at the Video Server
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Discussion
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Drastic changes in the link capacity are often
associated with vertical handoffs.
Most traditional streaming algorithms
incorporate the well-known slowly-responsive
congestion control (SlowCC) and thus cannot
take aggressive advantage of the rapid change
of resources in emerging vertical handoff
scenarios.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Discussion (cont.)
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For a handoff from LOW to HIGH, VTP can
properly and rapidly adapt its sending rate and
video quality to available bandwidth, and hence
is successful in handling vertical handoffs.
For a handoff from HIGH to LOW, application
performance would benefit if the server could
predict the handoff and thus adapt its sending
rate in advance.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Conclusion
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We studied the need and evaluated the
performance of adaptive video streaming in
vertical handoff scenarios.
Experiments with handoffs from 1xRTT to
802.11b and vice versa have been carried out to
evaluate the performance of our proposed
solution.
Such a combination of adaptive video streaming
and seamless vertical handoff will become
desirable in the emerging ubiquitous mobile
computing environment.
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Adaptive Video Streaming in Vertical Handoff: A Case Study
Thanks!
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