What Is The Sigfox Protocol Stack?

The SIGFOX protocol stack is the software used by connected devices modem to generate radio frames and thus transmit SIGFOX messages.
The SIGFOX protocol stack which covers layers 1 to 4 of the OSI model is composed of frame, medium access control, and physical layers.

The SIGFOX protocol stack is located between the connected device and the SIGFOX network. It’s embedded in the connected devices to enable the radio frame modulation and emission to transmit the message.

The SIGFOX protocol stack is provided free of charge to modem manufacturers. It is embedded in millions of chipsets, system on chips or modules. No royalties are charged.

Let’s have a look at the different layers of this Sigfox protocol stack.
Firstly, the Frame layer gets the payload provided by the application layer and generates the radio frame in which a sequence number is systematically added.
Secondly, we have the medium access control layer. This layer adds fields for identification of the device as well as other standard parameters such as the error detecting code.
SIGFOX decided to remove any signaling for medium access control in the devices. This means that devices are not synchronized with the network, so they can seldom randomly access the physical resource.

Lastly, the physical layer determines how the SIGFOX signals are going to be synthesized. It’s about modulation: DBPSK in uplink and GFSK in the downlink. The bitrate is 100 bps or 600 bps, depending on the operation region. The transmission power reaches, for example, a maximum of 14 dBm in the European countries or 22dBm in North and South America. Operation frequencies are also managed by this layer (for example around 900 megahertz in FCC-like regions and 868 megahertz in the European countries).