Power Consumption Measurement and Clock Synchronization on Low-Power Wireless Sensor Networks Author : Yu-Ping Chen, Quincy Wu 1

Outline Introduction Application of Wireless Sensor Networks Low-Power WiFi Digital oscilloscope connection diagram. Power Consumption Measurement Low-Power WiFi ZigBee Clock Synchronization Conclusion and Future Work 2

Introduction Applications of Wireless Sensor Networks 3

Introduction cont. Low-Power WiFi system architecture 4

Introduction cont. Digital oscilloscope connection diagram. 5

Power Consumption Measurement Low-Power WiFi 6 --The electric current of beaconing status when the WiFi signaling strength is -32 dBm. --The electric current of beaconing status when the WiFi signaling strength is -79 dBm.

Power Consumption Measurement cont. 7 The start- up status of Low-Power WiFi. The start- up status of ZigBee.

Power Consumption Measurement cont. 8 The stand-by status of ZigBee.

Power Consumption Measurement cont. Average power consumption statistics. 9 Power StateZigBeeLow-Power WiFi Signaling strength -32 dBm-79 dBm Start-up W W Beaconing W W Stand-by W W

Clock Synchronization Clock synchronization of Low-Power WiFi devices by NTP. 10

Clock Synchronization cont. Clock synchronization flow chart with NTP. 11

Conclusion and Future work Compared with traditional WiFi equipment, the power consumption of Low-Power WiFi is reduced approximate 40%. The power consumption of Low-Power WiFi with start-up and stand-by status is lower than ZigBee. The power consumption of Low-Power WiFi device when it is receiving beacons from an AP, is twice of the power consumption at its stand- by status. 12

Conclusion and Future Work cont. The clock synchronization usually suffers from long latency problems in wireless sensor networks like ZigBee. We combines Low-power WiFi devices with NTP, it would be crucial to further investigate the efficiency and accuracy of NTP packet transmission. 13