Sigfox

Sigfox provides a cellular style network operator that provides a tailor-made solution for low-throughput Internet of Things and M2M applications. It connects remote devices using Ultra Narrow Band (UNB) technology and operates in the unlicensed bands (ISM). It uses a standard radio transmission method called binary phase-shift keying (BPSK).

There are a number of applications that need this form of low cost wireless communications technology. It requires an inexpensive endpoint radio and a more sophisticated base station to manage the network. It is mainly targeted for low data rate applications. It requires substantially less antennas compare to traditional cellular networks such as GSM/CDMA. Sigfox has tailored a lightweight protocol to handle small messages. Less data to send means less energy consumption, hence longer battery life.

Using the Ultra Narrow Band modulation, Sigfox operate in the 200 kHz of the publicly available and unlicensed band to exchange radio messages over the air (868 to 869 MHz and 902 to 928 MHz depending on regions). Each message is 100 Hz wide and transferred at 100 or 600 bits per second a data rate, depending on the region. Hence, long distances can be achieved while being very robust against the noise. The transmission is unsynchronized between the device and the network. The device broadcasts each message 3 times on 3 different frequencies (frequency hopping). The base stations monitor the spectrum and look for UNB signals to demodulate.

The density of the cells in the Sigfox network is based on an average range of about 30-50km in rural areas and in urban areas where there are usually more obstructions and noise is greater the range may be reduced to between 3 and 10km. Distances can be much higher for outdoor nodes where SIGFOX states line of sight messages could travel over 1000km.