Doc.: IEEE 802.11-06/1747r0 Submission November 2006 Thomson Inc.Slide 1 Power Saving Limitation for...
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Novembe r 2006 Thoms on In c. Slide 1 doc.: IEEE 802.11-06/1747r0 Submission Power Saving Limitation for Multicast Applications Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures < http:// ieee802.org/guides/bylaws/sb-bylaws.pdf >, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <[email protected] > as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If Date: 2006-11-09 N am e C om pany A ddress Phone em ail X iaojun M a Thom son Inc. Rm 03-09,8F,Building A , Technology Fortune Center,8 X ue Q ing Road, H aiD ian D istrict, Beijing 100085, China +86-10- 58837105 Xiao- jun.ma@ thoms on.net H ang Liu Thom son Inc. 2 Independence W ay Princeton, N J08540 +1-609-987- 7335 Hang.liu@tho m son.net Authors:
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Transcript of Doc.: IEEE 802.11-06/1747r0 Submission November 2006 Thomson Inc.Slide 1 Power Saving Limitation for...
November 2006
Thomson Inc.
Slide 1
doc.: IEEE 802.11-06/1747r0
Submission
Power Saving Limitation for Multicast Applications
Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <[email protected]> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <[email protected]>.
Date: 2006-11-09
Name Company Address Phone email Xiaojun Ma Thomson Inc. Rm03-09,8F,Building A,
Technology Fortune Center,8 Xue Qing Road, Hai Dian District, Beijing 100085, China
+86-10-58837105
Hang Liu Thomson Inc. 2 Independence Way Princeton, NJ 08540
+1-609-987-7335
Authors:
November 2006
Thomson Inc.
Slide 2
doc.: IEEE 802.11-06/1747r0
Submission
Authors (cont.)Name Company Address Phone email Huanqiang Zhang
Thomson Inc. Rm03-09,8F,Building A, Technology Fortune Center,8 Xue Qing Road, Hai Dian District, Beijing 100085, China
+86-10-58837135
Jun Li Thomson Inc. Rm03-09,8F,Building A, Technology Fortune Center,8 Xue Qing Road, Hai Dian District, Beijing 100085, China
+86-10-58837105
Mingquan Wu Thomson Inc. 2 Independence Way Princeton, NJ 08540
+1-609-987-7323
November 2006
Thomson Inc.
Slide 3
doc.: IEEE 802.11-06/1747r0
Submission
Abstract
We give an overview of the power management scheme in 802.11 standards and discuss its limitation with regard to the multicast cases. We bring up the needs to help power conservation for multicasting applications, especially for video multicasting over WLAN. We discuss the possibility to make relevant MAC enhancements to the power management scheme with respect to these cases.
November 2006
Thomson Inc.
Slide 4
doc.: IEEE 802.11-06/1747r0
Submission
Outline
• Power management scheme in 802.11 standards
• The limitation of the scheme for multicast cases
• The needs for power saving
• General criteria
• Possible scope
• Conclusions
November 2006
Thomson Inc.
Slide 5
doc.: IEEE 802.11-06/1747r0
Submission
Multicast Applications
• IP TV at home
• Video multicast at hotspots– live TV, VoD
– Location dependent video content distribution• Advertisement in shopping malls
• Movie preview outside theaters
• Sports replay in stadiums
• Wireless video classes and video training for enterprise users
• …….
November 2006
Thomson Inc.
Slide 6
doc.: IEEE 802.11-06/1747r0
Submission
Power management scheme in 802.11 standards
• Two working modes, power saving mode (PSM) and Active mode (AM), are defined.
• Traffic indication map (TIM) and Delivery TIM (DTIM) elements contained in the beacon frames are used as the indication of pending unicast for stations and broadcast/multicast traffic at the AP.
• A mobile station in PSM shall send PS-Poll frame to the AP to retrieve the unicast traffic buffered on the AP.
• Broadcast/Multicast traffic shall be transmitted always before the unicast traffic transmission in each DTIM interval without resorting to PS-Poll/ACK scheme.
November 2006
Thomson Inc.
Slide 7
doc.: IEEE 802.11-06/1747r0
Submission
The limitation of the scheme for multicast cases
• Only one single bit in the DTIM element is used for indicating the existence of any buffered multicast / broadcast frames at the AP. – No discrimination between broadcast traffic and multicast traffic can be
made. Any multicast traffic in a beacon interval could lead to a PSM enabled mobile station staying in AM mode during the beacon interval even if the mobile station does not join any multicast group.
– No information is offered for discriminating the traffic among multiple multicast groups. Any multicast traffic belongs to one group may give rise to a PSM enabled mobile station staying in AM mode even if there is no multicast traffic destined to the group which the station belongs to.
• Insufficient information in the TIM / DTIM design results in too coarse granularity of the power saving scheme, which does not help efficient power conservation.
November 2006
Thomson Inc.
Slide 8
doc.: IEEE 802.11-06/1747r0
Submission
The needs for power saving• Why the needs?
– As the expectation of the next generation A/V over WLAN, video streaming applications are getting more and more popular on wireless devices.
– The key to prolong the life time for Power-consuming video steaming applications running on power-limited wireless devices is to manage the power efficiently.
• What about the power management performance in the current standards? Can it fit the needs?– Great power conservation can be achieved for PSM in contrast to AM.– According to the experiments, (which are shown in next following slides,)
the background multicast traffic have distinguishable impacts on the power consumption, although it has nothing to do with the mobile station.
– It is clear that the power management is not smart for video broadcasting / multicasting applications in current 802.11 standards.
November 2006
Thomson Inc.
Slide 9
doc.: IEEE 802.11-06/1747r0
Submission
The needs for power saving (Contd.)• Experiment environment:
– Server: Dell 600, for sending/receiving data and collecting traffic statistics information from clients.
– Client: PDA, HP iPAQ hx2750, for receiving traffic from the server
– Access point: DWL-2100AP
– Wireless sniffer: IBM T43, to receive background traffic and capture all 802.11 frames for analysis.
Dell D600 Access pointDWL-2100AP
IBM T43
AP
Server Client
wirelesssniffer
PDA HP IPAQ
Fig. 1 Experiment environment
November 2006
Thomson Inc.
Slide 10
doc.: IEEE 802.11-06/1747r0
Submission
The needs for power saving (Contd.)• Great power conservation can be achieved for PSM in contrast to AM
• Experiment scenario 1:
Compare the difference of power consumption between the Active mode (AM) state and the Power saving mode (PSM) state
under different multicast data rate.
• Results:
As Fig. 2 shows, much power can be
saved for the PS mode, especially
when the traffic is small or moderate.
0 500 1000 1500 2000 2500 3000 3500 40000
0.5
1
1.5
2
2.5
Data rate Units: kbps
Pow
er
Uni
ts:
W
AM
PS with DTIM =1
Fig. 2 Comparison of power consumption between AM and PSM for multicast
(Beacon Interval = 100ms, DTIM = 1)
November 2006
Thomson Inc.
Slide 11
doc.: IEEE 802.11-06/1747r0
Submission
The needs for power saving (Contd.)• The background multicast traffic have distinguishable impacts on the power
consumption.
• Experiment scenario 2:
Investigate the relationship between the power consumption and background multicast traffic rate. PDA receives a constant traffic rate of 500kbps while the background multicast traffic gets changed.
• Results:
It can be seen from Fig. 3 that the
amount of power consumption is
approximately a linear function of
the background multicast data rate.
The background traffic have
distinguishable impacts on the power
consumption.
0 500 1000 1500 2000 2500 30000.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
Background traffic Data rate Units: kbps
Pow
er
Uni
ts:
W
PS with DTIM =1, data rate = 500kbps
Fig. 3 Impact of background traffic on the power performance (Beacon Interval= 100ms, DTIM = 1)
November 2006
Thomson Inc.
Slide 12
doc.: IEEE 802.11-06/1747r0
Submission
The needs for power saving (Contd.)• Power consumption can be largely affected by the following conditions.
– Which mode is enable, AM or PSM?– The data rate of the desired traffic as well as the background multicast traffic data rate
• Experiment scenario 3: Compare the power consumption for multicast among three power status: AM, PSM without background traffic, and PSM with a 1.5Mbps background traffic. .
• Results: Fig. 4 demonstrates that the background multicast traffic has a distinguishable impact on the power performance, especially when the data rate is less than or comparable with the background traffic.
0 500 1000 1500 2000 2500 3000 3500 4000
0
0.5
1
1.5
2
2.5
Data rate Units: kbps
Pow
er
Uni
ts:
W
AM
PS without background traffic
PS with background traffic (1.5Mbps)
Fig. 4 Comparison of power performance among three cases: AM, PSM, and PSM with background traffic
(Beacon Interval = 100ms, DTIM = 1)
November 2006
Thomson Inc.
Slide 13
doc.: IEEE 802.11-06/1747r0
Submission
General criteria
• Redesign the TIM element to add more information for broadcast / multicast traffic discrimination
• Both AP and mobile stations should be aware of the new TIM / DTIM design
• Appropriate traffic scheduling scheme on the AP
• Compatibility with the existing standards
November 2006
Thomson Inc.
Slide 14
doc.: IEEE 802.11-06/1747r0
Submission
Possible scope
• Efficient power conservation scheme in terms of the new TIM / DTIM design
• MAC layer protocols to enable the new power management design
• Limited cross-layer information and interaction required, e.g., between MAC and IP layer
• Traffic scheduling scheme
November 2006
Thomson Inc.
Slide 15
doc.: IEEE 802.11-06/1747r0
Submission
Conclusions
• The power management design in current 802.11 standards has very limited capability to tackle power saving for multicast cases.
• The background multicast traffic may have distinguishable impacts on the power consumption especially when the data rate to the mobile station is less than or comparable with the background traffic. Therefore, there is still big room for us to decrease the power consumption for video broadcasting / multicasting cases.
• It is possible to design a new power conservation scheme to help power conservation for the mobile station, while keeping the compatibility with the existing standards.
