As a company primarily focusing on Battery Operated products, we emphasise making sure our devices stay awake for as little time as possible and consume as little energy as possible when they are asleep. As we work with different LPWAN technologies like NB-IoT, LoRaWAN, Low Power Satellite and Wirepas, we can observe and compare popular networks in production loads within similar constraints other than the network-specific infrastructure.
I wanted to discuss energy efficiency and our observations working with the LoRaWAN water level sensor in this article. Our devices are primarily designed to work on LoRaWAN class A which is meant for long periods of sleep and short transmission times. For monitoring applications, this is the ideal scenario. We observed that LoRaWAN devices are 20% more efficient during long sleep hours than their NB-IoT counterparts. At the microampere scale, this might mean just a few microamps and for devices that must transmit frequently, this may not be a difference maker, but for remote water tanks that used to be manually monitored once a week or twice a week, a device that transmits three or 4 times a day increases observability on the tank and at the same times lasts more than 10 years on a single battery charge.
LoRaWAN battery efficiency during transmission depends greatly on the spreading factor the device operates on. It can either make or break a LoRaWAN deployment. To explain in simple terms, the Spreading Factor (SF) in LoRaWAN is a parameter that determines the duration of the signal transmission and, thus, the range and energy consumption of the transmission. If you use your own gateways or know that your network has a gateway nearby, you can use a lower spreading factor, and the efficiency of the network stays intact.
But the spreading factor becomes a non-issue when it comes to water tanks or water troughs in a rural location or spread over large farmland. You can position gateways to accommodate all your assets for an SF closer to 7 and transmit with up to 50% less power compared to NB-IoT.
As you read through this blog post, you might have gotten the feeling that LoRaWAN is incredibly efficient, but it must operate less frequently and have gateways not too far from its location. While it is true that stars have to align for the peak performance of any IoT application, the difference between the most efficient deployment to the least efficient deployment is very high in the case of LoRaWAN. There are situations where NB-IoT shines compared to LoRaWAN, such as when you need a simple plug-and-play installation or to track a moving asset like a water delivery truck.
For stationary applications like water tanks or water troughs in farm areas, the efficiency of LoRaWAN is unbeatable If you spend the time setting up your own LoRaWAN network or use a public LoRaWAN network with gateways nearby. The deploy-and-forget nature of battery-operated IoT solutions comes to life with LoRaWAN, where devices operate in the field for 10 years on a single charge, in rain or sun, or winter's biting cold.
The devices mentioned in this post