One of the key technology developments that enables the IoT to reach its vision is much better battery life in wireless technologies. It’s important because it allows for devices to stay out in the field, serving its purpose without needing to be serviced (which costs a lot and reduces the product’s overall ROI). That’s why so many in the low-power, wide-area (LPWA) space are clamoring to claim long battery life.

Many try to look at the transmit power used to send a signal as a single metric for comparing battery life. Battery life is one of those complicated beasts that unlike coverage, which can be summed up using link budget, requires the whole system to be in place before you can know what it really is.

When it comes to battery life, it is better to transmit quickly at a higher power, than to transmit slowly at a lower power. Why? Well, that’s calculus my dear fellow! If battery usage is the area under the curve, then you want to minimize the area under that curve. So sending one acknowledged message at high transmit power very quickly (RPMA) uses far less battery than sending a single message three times because it isn’t acknowledged using less transmit power (e.g., Sigfox & LoRa technologies). Here’s a picture to demonstrate:

An analogous example, though with some differences but still illustrating the point, happens on our smartphones all the time. Assuming all else equal, when downloading a given large file or video, our smartphones use much less battery power on LTE versus 2G. The reason for this is that LTE uses a very short transmit time because it sends and receives data at a high data rate while 2G uses a much lower data rate over a longer time period.
This is a classic example of more advanced technology making things simpler for us as users. Technology is another word for making a machine of some sort do all the work we’d rather not do. That’s its job. And that’s what we’ve done with RPMA. If you want to have long battery life, with RPMA it’s simple, just use it.

Click here to download our white paper Six Secrets to Long Battery Life to learn the other things that go into building a device with long battery life.