Geolocation precision and possibilities¶
There are many ways how to do geolocation and indoor location with Sigfox especially when Sigfox is combined with technologies like GPS, WiFi and Bluetooth.
GPS - extreme precision¶
GPS is not always the most suitable of those as GPS needs a very long fix time, clear sky above you and the power consumption is high. Most people think that using GPS, they receive the same behaviour they receive on their mobiles, but this is not true as mobile phones use large lookup tables to speed up GPS fixes, GSM localisation, WiFI localisation, gyroscopes and magnetometers plus AI. And GPS can be easily scrambled/jammed.
So adding GPS to Sigfox device makes only sense when you can be sure the device sees the sky, doesn't need many positions or provide large battery and you can afford the price of the device.
Sigfox Atlas - lower precision¶
On the opposite end is the Sigfox (Atlas) Geolocation service that uses just Sigfox messages and their strengths to determine the location.
- No additional HW or processing is necessary.
- The price from Sigfox is reasonable for this service.
- The accuracy depends on network density (from our experience, the average precision is 1km).
- Big advantage is that the battery consumption is low and the objects can be located in deep indoor or in the wilderness.
- The most useful is this when you need to know at whatever airport your luggage ended or wherever your goods are in factory, on the way, on the border, in stock or with customers.
WiFi positioning - in between¶
In the middle between GPS and Sigfox Atlas when it comes to battery consumption, reach and precision is WiFi tracking.
WiFi tracking is based on the principle of a adding a cheap WiFi module to Sigfox device and listing the MAC addresses of nearby access points and their RSSI. In our devices, there are several ways to report the MAC addresses and there are also several ways to get the precise position. Generally, the device will send the MAC addresses to the Sigfox backend and they are then compared to a database of access points, which then returns the location.
The ways to get the position from the MAC addresses are:
- Sigfox Atlas WiFi - provided by Sigfox directly, the pros are that you do not need a 3rd party to process your MAC addresses as it's done directly on the Sigfox backend, the cons would be higher price for connectivity as this is a separate service and also that the precision might be slightly worse than the 3rd party databases. Whether or not you want to use this heavily depends on your use case.
- Google localisation services - slightly better precision (3 MAC addresses versus 2 MACs in Sigfox Atlas WiFi), but costs more and requires additional implementation.
- Your own database of WiFi access points - this requires the most effort on your part but can be well worth it as this can get you a precision of <1m in a fixed location (such as a warehouse or a production facility). The cost differs per use case, but a single access point can be as cheap as $10 per station.
Advantages of WiFi tracking include low cost, low power consumption and working indoors (when compared to GPS). In locations not covered by WiFi or the service, it can be combined with the default Sigfox Atlas geolocation service as a fallback.
Precision depends totally of the mode of deployment and quality of the WiFi database. In field testing it is between 5 and 100m.