Three Critical Considerations for Cellular IoT Design

Published on August 16, 2019

Three Critical Considerations for Cellular IoT Design

As we recently discussed in our White Paper, “Choosing the Right Route to Low Power Cellular IoT,” there are lots of approaches to designing your product for IoT with cellular as the primary communications route. And as we discussed in our previous blog post, the two primary low-power IoT specifications, NB-IoT and LTE-M, are both quite different and ideally suited for different kinds of low power wireless. We have frequently focused in the past on selecting the right technologies to make your design a success, which is with good reason: it’s a fundamental decision, and it heavily impacts the design choices you’ll be able to make afterwards.

However, a great IoT design is also one that works as efficiently as possible within the constraints of its platform, technologies, and other limitations. Consider NB-IoT: as we discussed in our last post, its low power characteristics, narrow frequency bandwidths, and relaxed latency make it possible to deploy a device on NB-IoT that lasts for years without a change of batteries. But that is a round estimate, and possibly an overestimate if your device tries to do too much, communicates too frequently, isn’t conservative with its data sharing, or otherwise doesn’t function efficiently.

These kinds of considerations can have a huge impact in your cellular device’s battery life, as well as the cost to deploy on a cellular network where data is at a premium. In the following sections, we’re going to focus on the first three of the primary conclusions of our White Paper, “Choosing the Right Route to Low Power Cellular IoT,” which have huge impacts on the effectiveness of your cellular design.

1. Use the Right Technology for the Job

Yes, it’s a frequent discussion point around the IoT and one that we tend to drive at frequently, but the decision of which wireless technology to use is incredibly consequential to building a quality IoT product. It’s a bit like deciding how you’re going to travel for your vacation: you can pretty well ruin a vacation by choosing to take the 30 hour drive instead of the five hour flight. Picking a wireless technology is similar; some trips are just more suited for a flight, and some are just more suited for a drive. Finding the natural fit whose strengths are suited to your design is critical for a better, more efficient product that provides a better user experience.

This might mean deciding between sub-technologies, like LTE-M and NB-IoT, or it might mean deciding between wholly different WAN, LPWAN, or LAN technologies altogether. But it’s important not to shoehorn any design into a technology that isn’t ideally suited for it. If you’re trying to push too much data too frequently through a protocol that isn’t meant to handle it, some part of your design will have to suffer to make that happen.

Consider how and where the device will be used, and your device’s role in the broader ecosystem, to identify the right tools for the job.

2. Combine Cellular with Other Wireless Technologies

An incredibly powerful way to minimize your device’s overall cellular draw is to utilize multiple wireless technologies in your design. This means identifying what your overall device traffic is, especially between multiple deployed devices, and considering if there are better and more efficient ways to collect and distribute data from them.

This might mean, for example, that you have a deployment of 10 or so co-located sensor devices across a facility, all of which are taking measurements and gathering data. Rather than all of those devices transmitting infrequently over cellular, it may be instead that the best option is to deploy also a collector-type device, and for all sensor devices to transmit their measurements via Bluetooth to that collector device. Then, that collector can transmit over cellular on a regular interval, making it the only device that does so. This may mean greater power savings for the sensors, offloading some greater power usage to the collector device, which can be centralized and powered via a DC outlet.

For however it’s implemented, the important takeaway is that integrating multiple wireless technologies can have a dramatic impact on what’s possible with your devices and may enable use cases that are better for your solutions at large. Exploring the ways that your devices are used together, the wireless (and wired) communications available around them, and the advantages of each is a powerful way to achieve efficiencies in your applications.

3. Avoid “Oversharing” When It Comes to the Cloud and Data Management

As a designer, it can be very difficult to put restrictions on your exciting new IoT design. How much should the device be able to send? How current to measurements or data points need to be logged in cloud software? Do we need to know a status every hour, or every minute, or every second? If your answers are more frequent than what is actually needed for your design to succeed, you’re probably overutilizing data – and overutilization has consequences for battery life and data costs.

Even though low power, low data protocols like NB-IoT and LTE-M are designed to make data costs more manageable, a constantly-open data pipe (or worse, a bidirectional one) between client and cloud can have significant costs for OEMs. A successful IoT deployment isn’t necessarily the one that is most up-to-the-minute, or measures the most data points, or fills the most server space. It really is the one that works the most intelligently between the sensor or client level and the cloud to decrease that burden. It’s important to balance what the device sends and receives, what the cloud asks for, and how the two devices interact on a continuing basis.

Learn More in our Cellular White Paper

There are four more lessons that Laird Connectivity outlines in our cellular white paper, involving certifications, antennas, carriers, and more important considerations to building a successful IoT deployment. And it’s important to keep these in mind very early in the design process, because the more time you invest in a path in your design, the harder it may be to reverse gears and adjust the plan for the unexpected.

Read our white paper, “Choosing the Right Route to Low Power Cellular IoT,” to learn more.