The Definitive Guide to Sigfox
History
Founded in Toulouse, France in 2010, Sigfox have been a pioneer in the development and deployment of their public low power wide area (LPWA) network.
Their technology, designed from the outset with the needs of low data rate IoT applications in mind. Sigfox provides the reliable delivery of short burst messages. The Sigfox approach to LPWA has been to offer a service globally for devices that need to communicate small messages such as an alert or a status update in situations where mains power or vehicular power is not available.
Sigfox license their technology mostly through SNOs (Sigfox Network Operators) but also operate networks directly in some countries including France, Germany and the USA. They supply the base station equipment along with all the network operating and billing systems to support the SNO service. SNOs manage their networks but have recourse to the Sigfox NOC (Network Operation Centre) for support if needed.
In 2019 Sigfox introduced the concept of a 0G (zero G) networks, using this designation in their PR. The concept was put to the International Telecommunications Union (ITU) highlighting the following unique characteristics:
- it is low cost for the user and operator
- The devices have low power consumption with predictable battery lifespan
- It is a globally scalable architecture
- It provides wide area coverage with excellent indoor and below ground penetration
- The network is based on software defined radio technology, well suited to AI and Blockchain
Sigfox Technology
Sigfox uses the unlicensed radio bands at 868 MHz in Europe and 915 MHz in North America. It is worth noting that although these frequencies are unlicensed, they are regulated.
In Europe, radio authorities use an ETSI standard allowing each device working in these frequencies a 1% duty cycle. This means that if a message takes 1 second to send, the device must ‘rest’ for 99 seconds .
In the USA the FCC regulations do not impose a duty cycle but they do stipulate a time-limit of 400 milliseconds to send a message. Sigfox have modified their technology to adapt to this regime in the USA.
Other competitors use these same frequency bands but there are different approaches to how they are used. Sigfox uses an Ultra Narrow Band (UNB) methodology where the network base station ‘listens’ to a very narrow (100 Hz) part of the spectrum taking longer than other technologies to complete a message transfer from the IoT device.
The data rate on a Sigfox network is only 100 bps which takes 6 seconds to send a 12 byte message - the maximum Sigfox payload. That means that in Europe, defined by ETSI standards, a device connected to the Sigfox network can send for 36 seconds in every hour (3,600 seconds). That therefore means 6 x 12 byte messages per hour or 144 messages per day.
In a Sigfox network, the intelligence and complexity is in the base station, allowing the remote transceiver to be very simple and consequently very cheap, the cheapest of any IoT network hardware.
There is no synchronisation between the network and the device sending the message. The device sends its message on a randomly selected frequency within the allocated bands then sends two replica messages on different frequencies. This method is called ‘time and frequency diversity'. The device is sending each message for 2 seconds, resulting in the 6 second total send time.
Benefits of Ultra Narrow Band (UNB)
The UNB method allows Sigfox to deliver messages with very high levels of reliability and without using re-tries. This approach allows Sigfox to offer two Service Level Agreements (SLAs) to its customers, an ‘IoT uplink delivery time’ (UDT) commitment of no less than 98% and a service availability guarantee of 99% per calendar quarter.
Sigfox is architected as a ‘star’ network, this means your device is not attached to a specific base station as it would be in a cellular network (2G, 3G etc). Typically a message sent from a Sigfox connected device is received by 3 base stations. SLAs are underpinned by a combination of the UNB approach to receiving a message and the transmitting device sending it 3 times.
Of all the LPWA technologies, Sigfox presents the customer with the cheapest hardware and on an application by application basis offers the longest battery life. The very slow bit rate does not suit all IoT applications however.
Typical Sigfox Applications
| Application | Benefit | Solution Providers |
|---|---|---|
| Connected Waste/Recycling Bins | Optimised collections. Data shows that measuring levels of waste in the bin reduces collections by 30% | Contelligent Sayme |
| Gas Tank Monitoring | Optimised delivery and collection routes | Silicon Controls Ijinus |
| Supply Chain & Logistics | 40% improvement in ETA, 30% reduction in Opex, | Box-Id Everysens |
| Smart Parking | Reduced driving time, Co2 reductions, improved capacity utilisation. Sensors connected to a mobile phone application route drivers to a vacant parking space. | Libelium Pnicorp Yazamtec |
Getting on board
For customers wishing to connect their devices to the Sigfox network, Sigfox offer rapid on-boarding which can be managed in two ways:
- Bundled Subscriptions. The device is pre-on-boarded and auto activates when it sends its first message.
- A la Carte. If a customer decides to purchase devices that do not have subscriptions at time of purchase the on-boarding process requires an additional step where a file identifying the device is uploaded to the global Sigfox on-boarding portal. Every Sigfox device is built with a unique pair of identifiers called an ID-PAC. These are stored in a file on the NVRAM (non-volatile memory) on the device itself. After loading this file, the device sends its first message and the process completes as for Bundled Subscriptions.
The Sigfox network supports bulk on-boarding and can accommodate up to 200,000 device ID file uploads at a time, taking approximately 3 to 5 minutes to complete an upload of this size.
Battery Life
| Example Application | Messages/Day | Expected Battery Life* |
|---|---|---|
| Alarm Notifications | 1-5 | >10 years |
| Low Use Sensors | 5-25 | >7 years |
| High Use Sensors | 25-100 | >5 years |
| Location/Tracking | >100 | >2 years |
* using same size battery in each application case
Sigfox Ecosystem
The rights to Sigfox IP are available to chip makers and device manufacturers free of charge and with no licensing fee or no follow-on royalties. This has resulted in a well-developed eco-system of semiconductor modules and devices certified for connection to Sigfox services. As of January 2021 there are over 900 devices either already certified or going through the certification process.
The costs of certification range from €500 to €1500 depending on whether the device is a module based or chip on-board design. These costs are in the order of 10 times lower than certification for cellular networks. Certification of devices includes not only validation of a product to regulatory standards, but also certification at the service level. This ensures interoperability for customer applications across the Sigfox network globally.
Information on the Sigfox ecosystem and compatible devices is constantly evolving to provide an increasing range of capabilities for those wanting to use IoT.
Working with other Networks
Sigfox LPWA services do not compete with existing connectivity services such as Wifi or cellular, they complement them. Cellular networks operate in synchronous mode, requiring hand-shake protocols to request access to the channel for message transmission and constant ‘keep alive’ signalling to and from remote devices.
Sigfox works in asynchronous mode with its UNB technology, delivering short messages with high reliability and minimum use of power.
Existing IoT applications can work better when Sigfox and cellular services are both deployed. An example could be the tracking of assets, in the case of loss or theft. Whilst it is where it should be the asset is monitored using a Sigfox connected sensor. However, once it moves outside a predefined area, or geofenced location, the cellular network takes over to track the asset in motion.
Whilst static, using Sigfox the sensor is using very little battery power. Once the asset is in motion the Sigfox network will alert the customer, while the cellular network begins GPS or A-GPS (using cellular network triangulation) tracking of its location.
Using Sigfox services in conjunction with cellular services can also maximise connectivity ‘up time’, essential for mission critical or business critical applications
In Conclusion
Sigfox offer IoT connectivity on a robust, carrier class low power wide area network.
- Sigfox enables new applications to be deployed which were not feasible previously due to power requirements and high cost.
- The reliability of the network technology underpinning Sigfox services ensures customer data will be delivered to contracted service levels, underwritten by SLAs.
- Customers have a big and growing choice of devices for off-the-shelf connection to Sigfox LPWA services.
- Sigfox carrier class IoT network services are complementary with existing cellular services and can enable innovative new applications in partnership with them.
