Low Power Gelocation Solution. Stéphane BOUDAUD CTO Abeeway Jonathan DAVID Polytech Student

Transcription

1 Low Power Gelocation Solution Stéphane BOUDAUD CTO Abeeway Jonathan DAVID Polytech Student

2 Disruptive radio technologies is taking off for IoT 2 An estimated 50 billions of connected objects by 2020 [CISCO] Many wireless technologies already available: WMBUS, Wireless HART, DECT, WIFI, Zigbee, BTLE, GPRS/3G/4G used in various applications New technologies are appearing and opening new opportunities and challenges. The requirements for most connected objects are: Low cost, small size Long battery life time Long range communication for indoor and outdoor coverage Mobile devices Privacy and security Bi-directional link Limited data rate Low Power Size Cost Indoor/ Outdoor

3 Low Medium High Low Data Rate Network for IoT applications 3 Data Rate (Mbps) G 3G 2G 1G 1 New technologies coming >1000 Local Area Network (WPAN) Wide Area Network (WWAN) LOW POWER, Wide Area Network (LPWAN) Range (m)

4 Efficient radio to minimise power consumption 4 Using asynchronous network access Transmit only when required, Communication triggered by end device Adaptive data rate (ADR) Trading efficiently data rate for sensitivity, Vastly increase the average battery life time Adaptive Output Power and high sensitivity receiver System Data rate TX power (dbm) Receiver Sensitivity (dbm) Receiver ANT gain Max Path Loss 2.4Ghz 1Mbit/s dBi 112dB 2.4Ghz 250kbit/sec dBi 98dB BT 2.4Ghz 1Mbit/s dBi 97dB 2GSM 144kbit/s dBi 158dB 868Mhz LORA 300b/sec dB dBi 6.6kbit/sec dB

5 Abeeway, Geolocation services for IoT network 5 Connecting Objects to new IoT networks, enhanced by Abeeway Sensors IoT networks Smart geolocated Smart transport Smart geolocated Smart lighting Smart geolocated Smart supply chain Smart geolocated Smart retail Smart geolocated Smart auto safety Smart geolocated Smart farms Smart geolocated Smart health Data server Smart applications Geolocation devices Geolocation Server + + Geolocated Apps

6 How to geolocate a connected object? 6 With radio technology : Global Navigation Satellite System (GNSS) like GPS, GLONASS Most accurate solution in open space and outside by measuring signals from satellites Need 4 satellites in view of the object to get X, Y, Z and clock deviation Time of Arrival (TOA) is the travel time of a radio signal from transmitter to receiver Fairly accurate but needs synchronisation between transmitter and receiver Radio Signal Strength (RSSI) can indicate distance between a transmitter and a receiver based on path loss. Free Path Loss Real life path loss affected by buildings, reflection, multi-path. Usable for short distance with limited accuracy With sensors : accelerometer, compass.

7 Low power tracker using WIFI technology 7 PRINCIPLES : WIFI radio senses local Access Points, collects BSSID with the related RSSI IoT radio transmits the data to the geolocation server to calculate the position. Application server with the API shows position to the user

8 WIFI tracker with optimised power consumption 8 Device is activated with a MEMS, otherwise device in sleep mode Optimise Radio performance Vs power consumption Design techniques to save power (battery powered device) Power gating for sub-systems High efficient power management with switch mode power supply and LDO System design with several power modes (OFF, Idle, WIFI ON, IoT ON) Microcontroller with flexible energy management system to control power modes and system clocks. Transmit power optimised with high efficiency antenna (Pout=14dBm) Minimised payload Scan WIFI TX Data Waiting For RX Tracker activation IDLE OFF

9 GPS versus the WIFI tracker 1/2 9 To compute its position, the device must first compute where are the satellites at exactly this precise time. This is done using the ephemeris data. Time To Fix (TTF) depends on start conditions. Cold start : Receiver does not have time or position information, TTF: 50sec to several minutes Warm start: Last position and approximate time know, valid almanac, TTF: 35-45sec Hot start: Time and last position known, Valid ephemeris. TTF <5sec GPS needs high sensitivity receiver to retrieve signal Acquisition sensitivity under a cold start : -154dBm Tracking sensitivity to maintain location fix (hot start) : -144dBm

10 GPS versus the WIFI tracker 2/2 10 Environment GNSS Outdoor anywhere on the earth WIFI Indoor/ outdoor where known coverage Standard accuracy Power consumption Other parameters Tens of meters at cold start 1-2 meters in 2D position 0.7mAh: 1 fix at cold start 20mAh: in continuous tracking mode High cost chipset and antenna Large circuit area for high performance Limited to meters (based on experiments) 20uAh per scan Can provide high data rate link.

11 Conclusion 11 Many applications need to link the measured data (sensor) with the end device position. Geolocation data can be provided from various technologies depending on the environment. Battery life time is increased with Low Power Wide Area Network radio to transmit the information The right technology to provide the position A geolocation platform (server) to control end device (downlink) and off load any computation (uplink).