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Yao Liu @ George Mason UniversityFei Li @ George Mason University
Lei Guo @ MicrosoftYang Guo @ Bell Labs
Songqing Chen @ George Mason University
BlueStreaming: Towards Power-Efficient Internet P2P Streaming to Mobile Devices
Internet streaming• Internet video streaming is gaining increased
popularity in practice– 90% of Internet traffic will be video by 2014
• Internet peer-to-peer (P2P) streaming is also popular
– P2P TV has generated 6% of total Internet traffic today
Internet streaming to mobile devices• Mobile devices are pervasively used today to
access streaming services
More than 66% of mobile network traffic will be video by 2015
Streaming to mobile devices is challenging
• Heterogeneity among devices– Software: different mobile operating systems, supported
audio/video codecs…– Hardware: different screen sizes…– Connection: 3G, WiFi, WiMAX, …
• Less reliable wireless connections• Slower CPUs• …• Limited battery power supply• Major power drainage sources:– CPU– Display– Wireless network interface card (WNIC)
How to save the power consumed by Wireless Network Interface?
30% ~ 40%
Power saving for P2P streaming to mobile devices is even more challenging
• In addition to downloading, a peer is expected to upload an equivalent amount to other peers in order to get service– Tit-for-tat
• In order to upload and download, a peer has to frequently exchange control packets with neighbors– Buffermaps– Fine-grained data requests
• Streaming data is downloaded from multiple and dynamically changing neighbors
Our contribution• Through Internet measurements, we confirm the
uploading traffic, control traffic significantly prevent the WiFi interface from switching to sleep mode
• We propose to leverage Bluetooth to transmit highly frequent and low throughput control traffic in P2P streaming for mobile devices
• We design and implement BlueStreaming, which trades Bluetooth’s power consumption for greater power saving from WiFi via intelligent traffic shaping
Outline
• Introduction• Internet Measurement• Design of BlueStreaming• Evaluation• Conclusion
P2P streaming consumes more energy than C/S based streaming on iTouch
Architecture Encoding Rate (Kbps)
Sleep Time (%)
TVUPlayer P2P 281 26Justin.tv C/S 281 83
iPod Touch
• Experiments on iPod Touch– Use Pwr Mgt flag to determine the sleep time
P2P streaming consumes more energy than C/S based streaming on laptop
Architecture Encoding Rate (Kbps)
Sleep Time (%)
Avg. # of Neighbors
PPTV P2P 400 4.42 12PPS P2P 396 0.09 20SopCast P2P 530 0.99 3QQLive P2P 500 7.12 4Justin.tv C/S 433 21.44 n/a
Laptop Windows 7
• Experiments on Laptop running Windows 7:– With maximum WiFi Power Saving Enabled
60-75% total transmitted packets are control packets
SopCast (530 Kbps) QQLive (500 Kbps)
PPTV (400 Kbps) PPS (396 Kbps)
Significantly reduces inter-packet delay
Results in less sleep time, and more power
consumption
Smaller than streaming data
packets
Up to 2 times more than streaming data traffic
SopCast (530 Kbps) QQLive (500 Kbps)
Control traffic throughput is low
PPTV (400 Kbps) PPS (396 Kbps)
Throughput is generally less than 100 Kbps
Smaller compared to the streaming rate of
400 - 530 Kbps
Uploading traffic varies
SopCast (530 Kbps) QQLive (500 Kbps)
PPTV (400 Kbps) PPS (396 Kbps)
Throughput of uploading traffic varies between 10 Kbps to 1.5 Mbps
MAX MIN
PPTV 4.42% 0.08%
PPS 0.09% 0.00%
SopCast 0.99% 0.22%
QQLive 7.12% 4.33%
Summary
• Control packets are delay-sensitive, highly frequent, but their throughput is low
• Uploading traffic changes dynamically, and could reach a very high throughput
• # of neighbors directly affect the control traffic and uploading traffic amount, the response time variance further shortens inter-packet delay
Outline
• Problem Statement and Proposal• Internet Measurement• Design of BlueStreaming• Evaluation• Conclusion
• Let the media traffic arrive in a predicable pattern:– Periodic bursts– WiFi can work / sleep correspondingly– Allows the WiFi interface to exploit more sleep
opportunities
Traffic shaping
Time
Sleeping
Time
How about direct traffic shaping?
• With traffic shaping:– Control packets, streaming data packets, and
uploading packets are scheduled together periodically
– Delayed control packets caused:• Playback freezing, distortion• 10% more streaming packets are received
QQLive500 Kbps
Total # of Streaming Packets
WiFi Sleep Time (%)
Distortion/Freeze Time (%)
Adaptive PSM 109,800 5.24 0
WiFi with traffic shaping 121,598 26.89 38
Control traffic is delay-sensitive!!
Re-requests
How about using Bluetooth directly?
• Using Bluetooth to access P2P streaming:– Bluetooth also has lower data rate, and cannot
afford the streaming rate– Only 34% streaming data packets were received
QQLive500 Kbps
Total # of Streaming Packets
WiFi Sleep Time (%)
Distortion/Freeze Time (%)
Adaptive PSM 109,800 5.24 0
WiFi with traffic shaping 121,598 26.89 38
Bluetooth only 37,228 n/a 96
BlueStreaming overview
• Traffic Classifier at AP and client:– Decouples control traffic from streaming data
traffic, and uses Bluetooth to transmit
• Traffic Shaper at the client:– Intelligently shapes streaming data downloading
traffic, and allows WiFi to save more power
• Uploading Scheduler at the client:– Handles the uploading traffic with minimized extra
power consumption
• Decouple control traffic from uploading traffic and streaming data traffic
• How can control traffic be decoupled from streaming data traffic transparently?
Traffic classifier: diverting control traffic to Bluetooth
WiFi
Time
• Control packets are identified empirically based on packet sizes
• Bluetooth is always on to transmit delay-sensitive control packets
Traffic classifier: diverting control traffic to Bluetooth
Bluetooth
WiFi
Time
• Buffers streaming data packets at Access Point• Applies client-centric traffic shaping, and
schedules transmission in a burst periodically• How should the burst interval be set?
Traffic shaper: shaping ingress streaming traffic intelligently
??
TimeBluetooth
WiFi
SleepingSleeping
• How should the burst interval be set?–P2P streaming applications have a re-request
timer to determine if a chunk should be re-requested.• Application-specific
–Packets should be transmitted before re-request timer times out:
Traffic shaper: shaping ingress streaming traffic intelligently
• How can a client perform uploading with minimized battery power consumption?
• Priority-based Bluetooth Uploading
Uploading scheduler: scheduling uploading wisely
TimeBluetooth
WiFi
Sleeping Sleeping
• How can a client perform uploading with minimized battery power consumption?
• Opportunistic WiFi Uploading:– Allows WiFi to upload with a minimum consumption of
extra battery power– Works seamlessly with the PSM mechanism
Uploading scheduler: scheduling uploading wisely
TimeBluetooth
WiFi
Sleeping Sleeping
Infrastructure Mode• A dedicated AP with both
WiFi and Bluetooth• A BlueStreaming client
connects to the AP directly
Hybrid Mode• WiFi AP does not need to
support Bluetooth• An intermediate node relays
the control traffic to WiFi AP
Deployment issue
Outline
• Problem Statement and Proposal• Internet Measurement• Design of BlueStreaming• Evaluation• Conclusion
Implementation of BlueStreaming
• Prototype systems on Windows and Mac• Why laptop instead of mobile devices?– Desktop OS has more complete Bluetooth profiles
including Personal Area Network (PAN)– More P2P streaming applications are available on
Windows
Experimental setup
• Use our Windows prototype running on one laptop as BlueStreaming client to access:– PPTV, PPS, SopCast, QQLive
• Use one MacBook with Bluetooth and WiFi (802.11n at 2.4GHz) as the BlueStreaming Access Point
• In hybrid mode:– Another laptop is used to relay the control traffic
between BlueStreaming client and access point
Infrastructure mode: PPTV results
Sleep Time (%) Consumed Energy (J)
PSM-A 0.56 2005Classifier only 25.82 1745
PSM-A Classifier only
Infrastructure mode: PPTV results
Sleep Time (%) Consumed Energy (J)
PSM-A 0.56 2005Classifier only 25.82 1745BlueStreaming 60.50 1090
PSM-A Classifier only BlueStreaming
Energy consumption comparisons
PPS has very small re-request timeout
BlueStreaming effectively saves energy consumption for PPTV,
SopCast, QQLive
Conclusion
• A mobile client in P2P streaming consumes excessive power because of – extra control traffic– extra uploading traffic– dynamics of neighboring peers.
• BlueStreaming trades Bluetooth’s power consumption for greater power saving on WiFi interface via intelligent traffic shaping– Saves up to 46% battery power consumption
Thank you!
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