Back to the overviewThe wireless network for the Internet of Things
From wristbands for heart rate monitoring to heating and coffee machine controls to district heating meters – the number of digital applications and devices is constantly growing. However, not everyone needs to be constantly “on air.”
For example, the sensors monitoring water quality in the Darmstadt Woog don’t have to transmit their data around the clock. Sensors on vehicles are only activated when a location needs to be determined. The smart lighting in northern Darmstadt only needs to be turned on when people approach at night. And the level sensors in the large trash bins in public spaces only sound when a bin is almost full and needs to be emptied.
LoRaWAN (Long Range Wide Area Network) is the name of the technology used for all these applications. LoRaWAN is the core of the much-cited “Internet of Things” – without relying on the internet.
For this purpose, a dedicated LoRaWan network was set up in Darmstadt between more than 30 antennas. It operates on license-free frequency bands in the 868 MHz range. The advantage: The frequencies used also penetrate barriers such as basement ceilings in industrial buildings or older urban buildings. This enables a long range of up to 80 kilometers in open terrain – making LoRaWan attractive for applications in remote locations.
The transmission of messages over the LoRaWAN network occurs with a certain delay (latency) – but this does not affect its applications, as real-time transmission is usually not the requirement. The LoRaWAN devices are only activated when necessary, which significantly extends the lifespan of the batteries used. The trigger for activation can be a specific stimulus such as light or moisture, movement, or touch, which triggers a reaction: The sensor directly controls a device, such as a streetlight, and/or it transmits information to its responsible “gateway.” This activates additional sensors – possibly turning on additional streetlights – and transmits the message via the internet to the central platform. Data can be collected there and processed for statistical purposes – such as environmental data for climate monitoring. The message can also be forwarded by the platform – for example, as an order to empty garbage cans.
