Sigfox - Simplifying Low Power Wide Area Networks

June 08, 2016 // By EDN Europe
Tim Bonnett, Director at Alpha Micro Components
WiFi, Bluetooth, 3G (and LTE) - our world is so connected with wireless technologies that it’s hard to imagine a scenario today where connectivity is a challenge. But in fact, the connectivity needs of tomorrow are the needs of the IoT, and the needs of the IoT are very different from those of our consumer devices

Some of the most promising IoT applications in agriculture, oil and gas, utilities, and smart cities, require extremely wide area networks with very low power requirements that can’t be met with the traditional trinity of wireless technology.

Using ultra narrowband communications to enhance range, and a cellular model, Sigfox is a promising wireless protocol that solves the problem of low power, wide area connectivity. Instead of using gateways or mesh networking, Sigfox devices connect to base stations, which act like cell towers to connect devices directly to the internet. The result is a very energy efficient protocol with unprecedented ease of deployment and incredible range.

The Infrastructure Challenge

Whether it’s precision agriculture, smarter parking lots, or monitoring water usage, much of the value of the IoT lies beyond the reach of traditional connectivity technology.

WiFi connects our indoor spaces at high speeds but is a power hog when used for lower bandwidth applications. Bluetooth sips power, especially energy efficient Bluetooth Low Energy (BLE), but it has limited range.

Both Bluetooth and WiFi, as well as many other popular wireless protocols like ZigBee, require network infrastructure to connect devices to the cloud. An internet connection needs to be secured, and connectivity must be established for each device through routers with the capability to reach each device in the system directly or through mesh networking.

3G and LTE cellular technologies provide one of the more attractive connectivity options for IoT deployments that need to cover a larger area effectively. They not only boast long range connectivity but eliminate the need for gateways and routers. A 3G or LTE device connects to the internet directly through the base station, making IoT devices using this technology extremely simple to deploy. However that ease of deployment comes at a cost.

Cellular networking, especially LTE, is good at transmitting medium to high bandwidth data efficiently, but is relatively power-intensive for low bandwidth transmissions. In addition, subscription fees reasonable for mobile phone usage don’t make sense for sensor applications, especially when vast numbers of devices are being deployed.

Sigfox - Cellular for the IoT

Borrowing the cellular model from mobile telephony, Sigfox is a low power, long range wireless protocol designed for the IoT. Like mobile phones, it uses a system of base stations which devices communicate with to connect to the internet. Sigfox devices also use a subscription based similar to mobile phones, but fees per device are much lower, allowing for deployments of large numbers of devices.

With low bandwidth, low power IoT sensor applications in mind, Sigfox uses ultra-narrowband frequencies which limits speeds to just 100 bits per second, but achieves wide coverage per base station and long transmission ranges on the device end with very low power usage.  The narrowband frequency allows transmissions to pass through solid objects easily, giving good coverage in urban environments even where walls, buildings and other obstacles may be present.

Whereas ZigBee, Z-Wave or BLE connected devices must go through a router to connect to the internet, any Sigfox-enabled device is directly connected to the cloud. This ease of use