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Coexistence with WiFi for a Home Automation ZigBee product

Coexistence with WiFi for a Home Automation ZigBee product. Federico Dominguez, Abdellah Touhafi , Jelmer Tiete and Kris Steenhaut ,Erasmus Hogeschool Brussel Vrije Universiteit Brussel , Brussels , Belgium

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Coexistence with WiFi for a Home Automation ZigBee product

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  1. Coexistence with WiFi for a Home AutomationZigBeeproduct Federico Dominguez, AbdellahTouhafi, Jelmer Tiete and Kris Steenhaut ,Erasmus HogeschoolBrussel VrijeUniversiteitBrussel,Brussels, Belgium Communications and Vehicular Technology in the Benelux (SCVT), 2012 IEEE 19th Symposium on, 6-16 Nov. 2012 Adviser: Presenter: Yu-Jhang Chen Date: 102/12/18

  2. Outline • Introduction • Materials and Methods • Results • Discussion • Conclusion

  3. Introduction(1) • Home Automation(HA): • Heating Ventilation Air Conditioning (HVAC) • automatic garage doors • intruder detection alarms • smart sensors detect temperature

  4. Introduction(2)

  5. Introduction(3) • Tradition HA: • Expensive • Cabling difficulty • Now HA: • Cheap • Smaller • Offer wireless connectivity

  6. Introduction(4) • HA products exploit frequencies bands : • 433MHz, 868MHz, 900MHz, 2.4GHz • The 2.4GHz compared with 433MHz : • Higher data throughput • Worldwide availability as an Industrial Scientific Medical (ISM) band

  7. Introduction(5) ZigBee: • Advantage • low cost SoC platforms • High interoperability • Defect • WiFi, Bluetooth, Microwaves, cordless phones interference

  8. Materials and Methods(1) Window Shutter HA system: • Content : • Shutter motor and Remote Control (RC) • Extra features : • Position and error feedback • Security • Scalability

  9. Materials and Methods(2) • The minimalWindow Shutter HA system setup is just a Wall RC anda Window Shutter. The system can later be expanded with other RC modelsand more shutters

  10. Materials and Methods(3) ZigBeePRO: • Devices : • Texas Instruments(TI) CC253x SoC • 8051 8-bit microprocessor • AES coprocessor • USB controller • CC2591 RF

  11. Materials and Methods(4) Channel Allocation: • ZigBeedefines 27channels : • One in the 868 MHz band • Ten in the 915 MHz band • 16 in the 2.4 GHz band • WiFi channels: • Range from 1 to 13

  12. Materials and Methods(4) • system uses ZigBee channel 26 and is vulnerable to interferencefrom WiFi channel 13

  13. Materials and Methods(5) Goals of tests : • Confirm or negate whether WiFiinterference poses athreat to the product • Find recommendations to avoid interference • Find a simple method to detect the presence of disruptive interference during product installation

  14. Materials and Methods(6) • Packet Reception Rate (PRR) • Added a test function in the firmware • Counts all ZigBee packets flagged as test packets • RChave the capability to send test packets in bursts of 1000 packets per second

  15. Materials and Methods(7) System Responsiveness (SR): • Assumed that a userexpected • Response to UP, DOWN and STOP commands by an RC , around 300ms • response of shutter position feedback in the embedded LCD screen on the Multi RC while the shutter is moving

  16. Materials and Methods(8) • Cr is successfully executed commands • Cd is noticeable delay time • Ct is total number of commands • Fw is a weighted value for the quality of the LCD visualization

  17. Materials and Methods(9)

  18. Materials and Methods(10) WIFI interference: • Constructed a lab to test the affects: • Put in a metallic window frame to emulate • Used a Linksys WRT54GL and D-Link DIR-615 • Used iperf to generate synthetic UDP test traffic

  19. Materials and Methods(11) • X: distance of interference source • Y :WiFi traffic level • C:WiFi channel

  20. Materials and Methods(12) • Traffic rate Y equivalency in WiFi load

  21. Results(1) • Atdistances below 5 meters from interfe- rencesource the sy- stem is practiuzally unreachable. The ef- fectsof interference consistently dissipate after 15m in allchan- nels

  22. Results(2) • SRlevels of 10% or less, where the sy- stem is completely unresponsive,were observed at dista- nces of 5 meters or less from inter- ference source.

  23. Results(3) • Evenat this rel- atively low traf- fic level a small but noticeable degradation (a- round 80%) of system respon- siveness was observed.

  24. Discussion(1) Confirm: • WiFi can create harmful interference to ZigBeesystems • Distance to interference source and WiFi traffic level are key variables • Difficult to avoid the WiFi generate interference with real traffic

  25. Discussion(2) • Distance from interference source • A distance of 5 meters can be tolerated • 15 meters seems to be a safe distance to avoid harmful disruption • PRR vs. SR • PRR can give a me accurate measure of the expected performance • Measuring PRR is much simpler than measuring SR

  26. Discussion(3) • PRR vs. SR has a correlation value of 0.89. PRR% can the- refore be used to predict the performance of the HA sys- tem.

  27. Conclusion(1) • ZigBee can coexist with WiFi in a typical home environment • Precautions are taken into account • New standards such as Wireless HD and WiGig will not occupy the 2.4 GHz band

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