1. 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 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 1.Introduction 2.Materials and Methods 3.Results 4.Discussion 5.Conclusion

3. Introduction (1) Home Automation(HA): 1.Heating Ventilation Air Conditioning (HVAC) 2.automatic garage doors 3.intruder detection alarms 4.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 minimal Window Shutter HA system setup is just a Wall RC and a Window Shutter. The system can later be expanded with other RC models and more shutters

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

11. Materials and Methods (4) Channel Allocation : ZigBee defines 27 channels : – 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 interference from WiFi channel 13

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

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

15. System Responsiveness (SR) : Assumed that a user expected − 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 Materials and Methods (7)

16. 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 Materials and Methods (8)

17. Materials and Methods (9)

18. 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 Materials and Methods (10)

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

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

21. At distances below 5 meters from interfe- rence source the sy- stem is practiuzally unreachable. The ef- fects of interference consistently dissipate after 15m in all chan- nels Results (1)

22. SR levels 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. Results (2)

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

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

25. 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 Discussion (2)

26. 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. Discussion (3)

27. 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 Conclusion (1)