This first blog of a two-part series focuses on the initial steps of developing a low-powered IoT device:

Understanding the KPIs

The first thing to establish when it comes to IoT power considerations is that the Key Performance Indicators (KPIs) – particularly for cellular IoT – are very different to those of smartphones when it comes to designing chipsets, networks and applications.

Smartphone applications tend to focus on uploading and downloading large files, such as videos and images, as well as performing voice calls, website browsing and syncing with multiple social media platforms. As a result, we have become accustomed to charging our phones daily, even multiple times a day, depending on usage.

In comparison, typical IoT applications can be defined as “lazy,” in that they spend long periods in sleep mode, only waking up when they have something to transmit or are pinged by the network. Thus, minimizing power consumption during sleep stages is of paramount importance. Additionally, when the device has something to transmit, it must do so extremely efficiently, utilizing optimal energy for short message exchanges. Finally, developers must bear in mind the need for periodic firmware over-the-air (FOTA) updates, especially for devices that will be deployed in the field for ten years or more. Energy for this must also be taken into account when customizing battery power consumption.

The process of designing a low-powered IoT application

With that established, we can look at the process of designing a low-powered IoT application, for which there are eight essential steps:

Of primary concern is selecting the correct network configuration for low-power applications, for which there are two technologies implemented in cellular LPWA standards:

1.Power Saving Mode (PSM) is mostly suited for applications with device-originated traffic, such as smoke detectors, IoT buttons, smart meters and pallet trackers. In this mode, devices are typically not reachable by the network. If the device needs to be reconfigured, the device first needs to signal the cloud that it is available for such an update.

2.Extended discontinuous reception (eDRX) is better suited for devices that need to respond to network requests, such as wearables, devices with voice functionality, various trackers and utility meters with remote shutdown.

It cannot be overstated that power consumption is key for cellular IoT and must be the focus from the start to finish, throughout the entire design process.

 Read part 2, which looks at how to optimize a non-optimal IoT device for power consumption. And if you’d like to watch a recording of the webinar, it can be accessed here.

 This post also appears on the Altair LTE Blog.