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WakeWake--onon--WLANWLANNilesh Mishra, Kameswari Chebrolu,

Bhaskaran Raman and Abhinav Pathak

IIT Kan ur

Wake-on-WLAN

Nilesh Mishra, Bhaskaran Raman,

Abhinav PathakDepartment of Computer Science

and Engineering, IIT Kanpur

Power management for 802.11 mesh networks using

802.15.4

Kameswari Chebrolu

Department of ElectricalEngineering, IIT Kanpur

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802.11 Mesh Network

802.11 designed forindoor usage

Usage of 802.11 forlong distance

connectivity Power as a constraint

Lack of support incurrent hardware

Wake-on-WLAN

Introduction Related Work Motivation Results

Prototype Recent Addition Results Conclusions

Summary: Current 802.11 hardware isnot power efficient but is being used toprovide long distance connectivity

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Power ConsumptionMeasurements

A typical mesh node

Single board

computer based802.11 bridge/router

Directional Antenna

RF cable forconnections

*http://www.hyperlinktech.com/web/hg2424g.php

*



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Nilesh Mishra, Kameswari Chebrolu,


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Power ConsumptionMeasurements (continued)

Observations on power consumption: Increases with insertion of card Higher for Tx than Rx Considerable variation over

different card makes

Summary: Even idle powerconsumption is significant



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Nilesh Mishra, Kameswari Chebrolu,


IIT Kan ur

Trivial solution

Node 1Node 1

Node 2Node 2

Node 3Node 3

Node 4Node 4

Wired GatewayWired Gateway



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Requirements

Node 1Node 1

Node 2Node 2

Node 3Node 3

Node 4Node 4




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WOW!

Node 1Node 1

Node 2Node 2

Node 3Node 3

Node 4Node 4




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IEEE 802.15.4

Energy optimized

Low cost radio (< $5)

Works in the same2.4GHz as 802.11

Sensor motes

MicrocontrollerMicrocontroller

Power SupplySubsystem

Power SupplySubsystem

CommunicationSubsystem

CommunicationSubsystem

Sensing SubsystemSensing Subsystem

Application LayerSubsystem

Application LayerSubsystem

CPU

Memory

RadioRadioRadio

Software

Sensor

ADC/DAC

BatteryBatteryBattery



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Architecture

Node 1Node 1

Node 2Node 2

Node 3Node 3

Node 4Node 4


Nodes turned off

Remote turn on

Multi-hop setting Delay due to boot

up



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Architecture

RF switch

or splitter

Battery

Power

switchingcircuit

Node1

Antenna

Node2



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CCA modes of 802.15.4 Clear if energy below

threshold Clear if valid 802.15.4

packet Clear if valid 802.15.4

packet and energybelow threshold

Use of Chipcons CC2420CCA mode

Configurable frequencyand energy threshold

parameters Relay based switching

circuit

Does not store the state

Implementation Details Introduction

Related Work Motivation Results


Summary: 802.15.4 compliantradio is able to detect 802.11 traffic

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Wake-on-WLAN Features

On-demand, course-grained power on/off ofnetworking equipments at a remote site.

Use of off the shelf 802.15.4 compliant sensormotes working in 2.4 GHz.

Setting ideal for rural deployment. Usage of data channel itself for remote wake-up

No separate antenna (shared with 802.11equipment).



Detection of 802 11

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A laptop with D-LinkDWL650 802.11b card

running trafficgenapplication as data trafficsource

Packets of size 1462 bytesat 1Mbps with inter packetintervals of 10, 20 and

100ms

Polling of CCA pin on

sensor node every 3ms

Detection of 802.11Transmission



Summary: Traffic pattern of 802.11successfully replicated on motes

I d i R l

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Validation on 3.5KmIITK-Mohanpur link on

DGP testbed External antenna

connected Calibrated 802.11

card for determiningRxPower

Outdoor Evaluations Introduction



Summary: Low sensitivity of 802.15.4essential for working of Wake-on-WLAN inlong distance settings

I t d ti R lt

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Power consumption of Soekris acting as arouter/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

Sensor mote typical values: Vcc = 2.8V and I =23mA with CPU and Radio receiving.

Example Scenario Introduction



Introduction Results

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Eno_wow = Pup x Tup Ewow = Emote + Ebootup + Eusage where

Emote = Vmote x Imote x Tidle Ebootup = Pbootup x Tbootup Eusage = Pup x Tactive

Using above values

Eno_wow = 120 Whrs

Emote = 1.54Whrs Ebootup = 1.04Whrs

Eusage = 7.73Whrs

Thus power saving is:

(Eno_wow Ewow)/ Eno_wow Greater than 91%

Example Scenario Introduction




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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 Introduction




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Narrow band RF detector

Wake-On-Wireless [Shieh, etal]

Concept of smart brick andmini brick

Separate frequency channel for

wake-up Turducken: Hierarchical

power management for

mobile devices [Sorber, et al] Hierarchy of devices Decomposition of task

Use of WiFi detectors

Summary: Usage scenario for RuralNetworking and use of 802.15.4 is unique



Wake-on-Wireless

Turducken Wake-on-LAN

Separateantennafordetection

Yes Yes No

Separatedata andtriggerchannels

Suitablefor lowcost longdistancelinks

Yes No No

No No Yes

Related Work


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Application Scenarios

VOIP usage in a typical setup

10-30 calls of 1-2 minutes duration

Solar Power WiFi (http://www.green-wifi.org/) Low cost solar powered WiFi grid.

On-demand data retrieval for bridge monitoring.

Summary: Wake-on-WLAN is useful inenergy constrained use of 802.11 equipments

Introduction Related Work Motivation

Results


http://www.green-wifi.org/http://www.green-wifi.org/

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Applications

ExternalAntenna Base node

Node 4Node 3 Node 2 Node 1

IEEE802.15.4

IEEE802.11

BriMon Project

With: Hemanth HaridasCSE, IIT Kanpur

Introduction Related Work Motivation

Results



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Application

BriMon Project


t oduct o Related Work Motivation

Results



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Application

BriMon Project


Related Work Motivation Prototype Recent Addition Results Conclusions


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Signature pattern based Wake-on-WLAN

Checks for a pattern in a code window

Overcomes the problem of noise triggered falsewake-up

Works in existence of periodic or non periodicnoise.

Improvements in switching circuit

Latching circuit

Transistor based switch

New Developments Related Work Motivation



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Lack of power save mode in current WiFi Meshnetworking hardware

Novel Wake-on-WLAN mechanism for multi hopremote on-demand wake-up of mesh nodes.

Substantial power savings using Wake-on-WLAN (> 91%).

Prototype tested and verified for ruraldeployment

Newer applications emerging.

Summary: Power management tools arerequired for current 802.11 based networksdeployed in energy constrained scenarios

Conclusions Related Work Motivation


5506 Slides

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