WakeonWLAN

1
Wake-on-WLAN
Power management for 802.11 mesh networks using
802.15.4

• Nilesh Mishra, Bhaskaran Raman,
• Abhinav Pathak
• Department of Computer Science
• and Engineering, IIT Kanpur

Kameswari Chebrolu Department of Electrical
Engineering, IIT Kanpur
2
802.11 Mesh Network
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 802.11 designed for indoor usage
• Usage of 802.11 for long distance connectivity
• Power as a constraint
• Lack of support in current hardware
• Wake-on-WLAN

Summary Current 802.11 hardware is not power
efficient but is being used to provide long
distance connectivity
3
Power Consumption Measurements
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• A typical mesh node
• Single board computer based 802.11 bridge/router
• Directional Antenna
• RF cable for connections

http//www.hyperlinktech.com/web/hg2424g.php
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Power Consumption Measurements (continued)
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

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

Summary Even idle power consumption is
significant
5
Trivial solution
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
Node 1
Node 3
Wired Gateway
Node 2
Node 4
6
Requirements
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
Node 1
Node 3
Wired Gateway
Node 2
Node 4
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WOW!
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
Node 1
Node 3
Wired Gateway
Node 2
Node 4
8
IEEE 802.15.4
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• Energy optimized
• Low cost radio (lt 5)
• Works in the same 2.4GHz as 802.11
• Sensor motes

9
Architecture
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
Wired Gateway
Node 1
Node 3

• Nodes turned off
• Remote turn on
• Multi-hop setting
• Delay due to boot up

Node 2
Node 4
10
Architecture
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
Node 1
Antenna
RF switch or splitter
Power switching circuit
Node 2
Battery
11
Implementation Details
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• Use of Chipcons CC2420 CCA mode
• Configurable frequency and energy threshold
  parameters
• Relay based switching circuit
• Does not store the state

• 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 energy below
  threshold

Summary 802.15.4 compliant radio is able to
detect 802.11 traffic
12
Wake-on-WLAN Features
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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).

13
Detection of 802.11 Transmission
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• A laptop with D-Link DWL650 802.11b card running
  trafficgen application as data traffic source
• 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
14
Outdoor Evaluations
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• Validation on 3.5Km IITK-Mohanpur link on DGP
  testbed
• External antenna connected
• Calibrated 802.11 card for determining RxPower

Summary Low sensitivity of 802.15.4 essential
for working of Wake-on-WLAN in long distance
settings
15
Example Scenario
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

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

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Example Scenario
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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

17
Discussion
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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.

18
Related Work
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• Narrow band RF detector
• Wake-On-Wireless Shieh, et al
• Concept of smart brick and mini 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 Rural Networking and
use of 802.15.4 is unique
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Application Scenarios
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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 in energy
constrained use of 802.11 equipments
20
Applications
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
With Hemanth Haridas CSE, IIT Kanpur
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Application
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
With Hemanth Haridas CSE, IIT Kanpur
22
Application
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions
With Hemanth Haridas CSE, IIT Kanpur
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New Developments
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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

24
Conclusions
Introduction
Results
Related Work
Motivation
Prototype
Recent Addition
Results
Conclusions

• 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 (gt
  91).
• Prototype tested and verified for rural
  deployment
• Newer applications emerging.

Summary Power management tools are required for
current 802.11 based networks deployed in energy
constrained scenarios