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The Hitchhiker’s Guide to Successful Residential Sensing Deployments

The Hitchhiker’s Guide to Successful Residential Sensing Deployments

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The Hitchhiker’s Guide to Successful Residential Sensing Deployments

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  1. The Hitchhiker’s Guide to Successful Residential Sensing Deployments Timothy W. Hnat, Vijay Srinivasan, Jiakang Lu, Tamim I. Sookoor, Raymond Dawson, John Stankovic, and KaminWhitehouse U. Virginia Sensys 11 Presenter: SY

  2. Lesson Learned Paper • Large scale, long-term deployment in home • 1200 sensors • Over 20 homes • Up to 1 year/home • Experience sharing • Myths VS facts

  3. Myths • Sensors in homes can easily be powered using the wall sockets • Communication in homes can be achieved with single-hop wireless and/or power line modems • Robust enclosures are only important for extreme outdoor environments • Maintenance visits are not a problem for homes • Users can help maintain the system, and can provide validation data through surveys or questionnaires • Users won’t mind a few sensors around the house • Industry has already produced a wide range of suitable residential sensing systems

  4. What They Learned #Homes < #Researchers #Days < ~1 month #Sensors < #Outlets #Homes > #Researchers #Days > ~1 month #Sensors > #Outlets Difficulty #Sensors #Homes #Days

  5. Outline • Deployment • Failure Analysis • Hitchhiker’s Guide

  6. Deployments

  7. Deployments

  8. Deployments

  9. Why Such Deployments • V. Srinivasan, J. Stankovic, and K. Whitehouse. Protecting your Daily In-Home Activity Information from a Wireless Snooping Attack. In Proceedings of the 10th international conference on Ubiquitous computing, pages 202–211. ACM New York, NY, USA, 2008. • J. Lu, T. Sookoor, V. Srinivasan, G. Gao, B. Holben, J. Stankovic, E. Field, and K. Whitehouse. The smart thermostat: using occupancy sensors to save energy in homes. ACM Sensys, 2010. • V. Srinivasan, J. Stankovic, and K. Whitehouse. Using Height Sensors for Biometric Identification in Multi-resident Homes. In Pervasive, 2010. • J. Lu, D. Birru, and K. Whitehouse. Using simple light sensors to achieve smart daylight harvesting. In The ACM Workshop on Embedded Sensing Systems for Energy-Efficiency in Building, 2010.

  10. System Architecture Gateway Sub-systems

  11. Failure Analysis • Analyze the sensor down time • Method • Define a longest acceptable report interval τ • For each sensor • About 5x sample period • Classify root cause • based on the set of simultaneous sensor failures

  12. Classification • Wireless link loss • single wireless sensor, less than 4 τ • Battery dead • single battery-powered sensor, longer than 4 τ • Plug disconnected • single plug powered sensor, longer than 4 τ • Sub-system down • all sensors in a single sensor sub-system • Internet Down • all sensors reliant on a broadband link • Power outage • all sensors reliant on AC power • Gateway down • simultaneous down time of all sensors

  13. Summary January 1, 2011 to August 1, 2011

  14. Fault Analysis Reinstall Hard drive failure Sub-system failure Plug disconnections

  15. Outline • Deployment • Failure Analysis • Hitchhiker’s Guide

  16. Homes are Not a Power Panacea • Myth • Sensors in homes can easily be powered using the wall sockets • Fact • Wall sockets provide neither abundant nor reliable power, especially when deploying hundreds of nodes

  17. Wall Sockets • 30-40 outlets per house • Long wires • 2.3x more down time than batteries • More maintenance calls

  18. In-line Power & Indoor Solar • In-line power • Wired directly into wiring • Problem • Expensive • Reboot -- rebooting the house • Indoor Solar • Upper bound: 0.1mW • Compare to outdoor: 102mW

  19. Homes Have Poor Connectivity • Myth • Communication in homes can be achieved with single-hop wireless and/or power line modems • Fact • Homes are small but can still be challenging RF environments, particularly for large-scale, dense, and heterogeneous networks

  20. Wireless or Power-line • Wireless connectivity • Power line communications • Wires • 180bit/s • 5 min polling rate

  21. Homes are Hazardous Environments • Myth • Robust enclosures are only important for extreme outdoor environments • Fact • Homes are safe environments for humans but can be hazardous for sensors, particularly when hundreds of sensors are deployed over long time durations

  22. Homes are Hazardous Environments • Children • Mobile objects • Roomba • Guests and cleaning services

  23. Verify Failures • Mean time to failure (MTTF) • Deploy 500 sensors • One year MTTF means more than one sensor fail per day • Automated script to check

  24. Report Failure • By email • Too many • Project all critical alerts on wall

  25. Homes are Remote Environments • Myth • Maintenance visits are not a problem for homes • Fact • Investigators have very limited access to deployments not in their own homes

  26. Homes are Remote Environments • Minimize installation time • Scout • Lab assembly and configuration • Checklists • Test three time

  27. Expect Limited User Participation • Myth • Users can help maintain the system, and can providevalidation data through surveys or questionnaires • Fact • A user’s ability to monitor and report activities in thehome is limited by the need to do those activities, particularlyin long-duration deployments

  28. Expect Limited User Participation • Button Tracking • Wearable Tracking • Self-reporting • Surveys Use redundant sensing and multiple ground truth techniques 29

  29. Aesthetics Matter in Homes • Myth • Users won’t mind a few sensors around the house • Fact • Aesthetics constrain deployments, especially at large scale and over long time durations

  30. Aesthetics Matter in Homes • Disappear into the woodwork • Leave no trace • No LEDS at night • Noise

  31. Simplify the Architecture • Myth • Industry has already produced a wide range of suitable residential sensing systems • Fact • Many COTS devices were not designed for large scale deployments, and integration of many COTS platforms increases the possible modes of system failure

  32. Simplify the Architecture

  33. Summary • Wall socket is neither abundant nor reliable • Communication in home still challenge • Homes are hazardous environments • Homes are remote environments • User has limited participation • Aesthetics matter • COTSare a double-edged sword

  34. Conclusion • Some we might already expected • But some information still useful • Useful tips • Verify failure • Automated script • Project on wall • Check three time • COTS are a double-edged sword