From Domotics to Autonomous Sensors Based on SigFox, LoRaWAN or NB-IOT: Realistic Today?

From Domotics to Autonomous Sensors Based on SigFox, LoRaWAN or NB-IOT: Realistic Today?

Cabling is generally the most important cost, in terms of investment, in a Smart Home / Smart Building deployment. Motion, intrusion, door or window sensors, smoke detectors … Powering the sensors often requires wiring to a power source, or even adding a low voltage / direct current transformer. And of course the network cabling, or the use of a local wireless communications network (WIFI, BLE, ZigBee or Z-WAVE for example).

This is the entire scope of Domotics (or home automation), which sometimes also requires the implementation of a local Gateway. The cost of these installations, and the lack of standard and compatibility have always been a barrier to the widespread use of home automation, whether at home or in companies. In terms of the offer for consumers, Google, Amazon and Apple have made it one of their new battle horses, with the release of home gateways, video streaming boxes and voice control, which allow to interface sensors …

Today, there are very low energy consumption sensors, operating on battery with a range of up to 10 years, based on long-distance communication networks: SigFox, LoRaWAN or NB-IOT. Credible alternatives to the classic home automation sensors?

Comparison of the costs of the Domotics sensors or based on LORAWAN & SIGFOX

The price of sensors based on LORA or SigFox type Low Power Wide Area Network (LPWAN) technology has fallen sharply for some time (for NB-IOT, we will have to wait a little longer for this technology to mature …). We can consider that their price is close to a home automation sensor.

On the other hand, there is a difference in operational cost between a LORA / SIGFOX sensor and a home automation sensor.


Cost comparison between home networks and LPWAN networks (SigFox, LoRaWAN, NB-IOT)

In the case of the use of the SIGFOX network or of a public LORA network, there will be a subscription cost which, in Europe, is of the order of a few Euros per year per sensor.

In the case of a Domotics network, there is no subscription fee. There is a cost of electricity consumption. LPWAN sensors, battery operated, have been optimized to limit power consumption. The price of the sensor includes the price of the electricity consumption over a few years of use. In the case of a Domotics sensor, it must still be powered. It is not surprising, for example, to have a 1W consumption on a motion sensor. That is an annual consumption of 8.76 kWh. If we take a price of € 0.06 per kWh (average price in Belgium), this amounts to € 0.53 / year. While this is lower than the price of a subscription to an LPWAN network, but not negligible in terms of comparison. It will also take into account the cost of using the local network (eg WIFI) to transmit the data on the Internet, both at the electrical level and the DATA subscription.

On the other hand, the big advantage of a battery-powered sensor, connected to a LORA or SIGFOX type network, is that it will work 100% of the time, even in the event of a power outage in the building or in the home, or loss of the Internet connection. If the sensor has a safe function, this is a major advantage!

To fill this gap, some Domotics sensors (intrusion / theft detection, fire alarm) are equipped with an internal battery, and connected to the Internet through a SIM card (GPRS, 3G). They can therefore also work in case of power failure. But the cost of these sensors, both in terms of purchase and communication subscription, is much higher than the cost of acquiring and using SIGFOX or LORA sensors.

So, LORA and SIGFOX, a good alternative to GPRS / 3G?

We could therefore conclude that it would be time to move to LORA or SIGFOX for equipment in secure sensors (intrusion detection, theft, fire alarm). This is unfortunately not yet still true. It is indeed necessary that these LPWAN networks of new generations offer a global coverage, and in particular in “deep indoor“. That is, to be sure that they cover the entire building to be equipped. The current state of these networks (in 2018) does not yet allow this guarantee of global coverage. So in some cases it is an option. In others, we will have to wait. Or, if you have many sensors to install (residential or office buildings, industrial sites), deploy your own LORAWAN private network.

In addition, the SIGFOX and LORA networks are not without flaws as well. They operate on a free frequency band (ISM band), unlicensed, and may be theoretically disturbed by the presence of other networks, in the same immediate environment. Interference between networks is possible, where the GSM network (GPRS, 3G) has its own frequencies. This is also the case of NB-IOT.

The conclusion?

LPWAN networks such as SigFox, LoRa or NB-IOT have been developed to allow cheap, generally battery-powered sensors to communicate small amounts of data over long distances for years. These are technologies to seriously consider for some security / Domotics equipment. But there is still a need to check that they are already fully available and operational where they are being used.

Example of LORAWAN Smart Home - Smart Building (Domotics) Sensors