This is another Low Power Wide Area Network (LPWAN) technology that uses the unlicensed frequency spectrum.
SigFox was developed by the French telecommunications company of the same name. The technology is used in particular when large distances have to be bridged for data transmission, or when there is no easily available area-wide power supply to fall back on.
How does SigFox work and how does it differ from other transmission technologies?
According to the company’s own information, SigFox transmission technology currently covers 72 countries and, in addition, most of the airports important for the international transport of goods and people. Unlike LoRaWAN, a usable infrastructure is already in place and there is no need to build a separate network. This ensures that SigFox is particularly easy to install and put into operation. However, this also means that coverage of the area in question is essential in order to use the technology. Smaller holes in the coverage can be bridged with own amplifiers or receivers. In addition, the user is dependent on the company as a hardware supplier; independent use as with mobile radio-based technologies is not possible.
Technically, the sensor devices are limited to 140 data transmissions per day and 12 bytes per message when using SigFox. The also comparatively low transmission speeds and frequency times result in exceptionally low power consumption. Transmitters using SigFox can therefore be used for many years in battery operation. At the same time, however, the above-mentioned factors mean that the transmission technology is not suitable for all applications.
As already mentioned, SigFox technology uses the unlicensed spectrum. An open standard on sub-Ghz frequency bands is used, which every provider is allowed to use. The exact frequencies vary from country to country. In Europe, they are 868 MHz, in the USA, for example, 900 MHz. By using these spectrums, the license fees incurred in the mobile network are eliminated. In addition, SigFox enables the use of a global network without roaming charges. On the other hand, the open availability of the frequencies can also lead to interference.
Data collected from smart sensors and other devices is sent to the SigFox Cloud. The customer can access them via a programming interface. The characteristics described make the transmission technology particularly cost-effective. In addition, secure transmission of the data is guaranteed.
The application of SigFox in the Internet of Things
As already mentioned, SigFox is not suitable for all use cases. The transmission technology is not suitable for critical applications, such as emergency call systems. This is due to the susceptibility of the unlicensed frequency spectrum to interference and the limited number of transmissions performed.
Similar to LoRaWAN, SigFox is also frequently applied in smart city scenarios. However, the main application can be found in logistics: for this, SigFox is particularly well suited due to the broad coverage of international airports and the possibility of cost-effective global data transmission. For example, containers can be equipped with transmitters that constantly transmit coordinates, humidity, or temperature to transport companies using SigFox technology.
In addition, the transmission technology is used in the utility industry. It enables, for example, the monitoring of water supply networks and power poles, or the transmission of reservoir levels. In agriculture, soil moisture and nutrient levels can be transmitted, or the location of animal herds can be monitored. All these applications reduce the number of necessary on-site visits by skilled personnel.