While Sigfox is a very good technology for numerous projects, some use cases may not be feasible as of today.
1) Message size limitations
The Sigfox protocol is designed to be extremely efficient and allow devices running over our network to have many years of battery life. The 12 bytes payload (maximum, but flexible) of a Sigfox message is also perfectly suited for the vast majority of IoT use cases we see today, allowing devices to transmit interesting data to the cloud.
However, this technology is optimized for a specific kind of use case, meaning that some projects requiring high bandwith and constant connection are not really adapted for the Sigfox technology today.
2) Legal limitations
As the current version of Sigfox uses public radio frequencies (aka ISM bands), we have to comply with the sharing rules in place in the different regions of the world to keep these bands available for everybody.
For instance, in Europe, the ETSI regulation allows devices on these frequencies to send messages for 1% of the time per hour. Devices can only send a defined number of message per day to be compliant with the rule, and our commercial contracts were designed to match this limitation.
It is a direct application of the European ETSI regulation:
- There are 3,600 seconds in one hour.
- 1% of 3,600 is 36 seconds, so a device can emit for 36 seconds per hour .
- A Sigfox messages takes 6 seconds to send (for RC1 devices).
- Therefore, you can send 36/6 = 6 messages / hour, which makes 24x6 = 144 messages a day. We keep 4 messages for protocol use, which allows for 140 messages per day for your device.
NB: This calculation is just an example of what is done in EMEA region (Europe, Middle east, Africa). Depending on the location, limitations can be very different.
To get more details on the Sigfox technology, you can download the Technical Overview available below.