công nghệ thông tin 24 wakeonwlan

Wake-on-WLAN Nilesh Mishra, Kameswari Chebrolu,Bhaskaran Raman and Abhinav Pathak Department of Computer Science and Engineering, IIT Kanpur Power management for 802.11 mesh networks usi

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Wake-on-WLAN Nilesh Mishra, Kameswari Chebrolu,Bhaskaran Raman and Abhinav Pathak

Department of Computer Science

and Engineering, IIT Kanpur

Power management for 802.11 mesh networks using

802.15.4

Kameswari ChebroluDepartment of Electrical Engineering, IIT Kanpur

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Measurements (continued)

Observations on power consumption:

• Increases with insertion of card

• Higher for Tx than Rx

• Considerable variation over different card makes

• Results • Conclusions

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IEEE 802.15.4

• Energy optimized

• Low cost radio (< $5)

• Works in the same

2.4GHz as 802.11

• Sensor motes

Microcontroller

Power Supply Subsystem

Power Supply Subsystem Communication Subsystem

Communication Subsystem

Sensing Subsystem

Application Layer Subsystem

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1

Antenna

Node 2

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• Clear if valid 802.15.4 packet and energy below threshold

– Does not store the state

Summary: 802.15.4 compliant radio

is able to detect 802.11 traffic

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• On-demand, course-grained power on/off of

networking equipments at a remote site

• Use of off the shelf 802.15.4 compliant sensor motes working in 2.4 GHz.

• Setting ideal for rural deployment.

• Usage of data channel itself for remote

wake-up

• No separate antenna (shared with 802.11

equipment).

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• Packets of size 1462 bytes

at 1Mbps with inter packet

intervals of 10, 20 and

100ms

• Polling of CCA pin on

sensor node every 3ms

Summary: Traffic pattern of 802.11 successfully replicated on motes

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IIT Kanpur

• Power consumption of Soekris acting as a

router/switch with two wireless 802.11b cards = 7.7W (typical)

• Boot-up time for Soekris 50s

• VoIP service in Sarauhan in the DGP testbed

– Usage pattern: 15 calls/day of 71s avg duration

23mA with CPU and Radio receiving

Example Scenario • Results • Conclusions

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• E no_wow = P up x T up

• E wow = E mote + E bootup + E usage where

– Emote = Vmote x Imote x Tidle

– Ebootup = Pbootup x Tbootup

– Eusage = Pup x Tactive

• Using above values

• Thus power saving is:

– (Eno_wow – Ewow)/ Eno_wow– Greater than 91%

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IIT Kanpur

• Does not work on 802.11a

• Hibernation facility desired: faster boot-up

• Suffers from noise generated triggers

• Advanced usage: morphing topology

• More detailed study of usage pattern for better power savings.

Discussion • Results • Conclusions

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• Narrow band RF detector

power management for

mobile devices [Sorber, et al]

Wake-on-Separate antenna for

detection

Yes Yes No

Separate data and trigger channels

Yes No No

Suitable for low cost long distance links

No No Yes

Related Work

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IIT Kanpur

• VOIP usage in a typical setup

– 10-30 calls of 1-2 minutes duration

– Low cost solar powered WiFi grid.

• On-demand data retrieval for bridge monitoring.

Summary: Wake-on-WLAN is useful in energy constrained use of 802.11

equipments

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E

802 11

Bri Mon Project

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IIT Kanpur

Application

Bri Mon Project

With: Hemanth HaridasCSE, IIT Kanpur

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Bri Mon Project

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IIT Kanpur

• Signature pattern based Wake-on-WLAN

– Checks for a pattern in a code window

– Overcomes the problem of noise triggered false

wake-up

– Works in existence of periodic or non periodic noise.

• Improvements in switching circuit

– Latching circuit

– Transistor based switch

New Developments • Results • Conclusions

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• Lack of power save mode in current WiFi Mesh networking hardware

• Novel Wake-on-WLAN mechanism for multi hop remote on-demand wake-up of mesh nodes.

• Substantial power savings using

Wake-on-WLAN (> 91%).

• Prototype tested and verified for rural

deployment

• Newer applications emerging.

Conclusions • Results • Conclusions

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