Don’t Let Interference Hijack Your IoT Device’s Operation

2018-09-19  |  5 min read 

Here’s an important question for anyone developing an Internet of Things (IoT) device these days. How do you ensure it will work as expected in its intended environment? It may sound like a simple question, but it isn’t.

Potential sources of interference are lurking everywhere, threatening to hijack the functional wireless performance of your device. That interference can cause it to behave in unexpected and sometimes dangerous ways. The data collected by your device may be lost, its voice quality may be degraded, and its operating range may even decrease—none of which bodes well for an engineer or company wanting to develop a commercially successful IoT device.

Where is all this interference coming from? The obvious answer is just the sheer number of IoT devices in the world today. IoT devices are everywhere and more are coming online all the time. In a typical family home, for example, there are expected to be more than 500 smart devices alone by 2022. Many of these devices simply weren’t designed to play well together, especially when they are concentrated in a highly dense deployment environment.

The other problem is that the growing number of wireless standards makes it difficult, if not impossible, to allocate separate frequency spectrum to each. As a result, different standards are forced to share the same frequency bands, with new applications regularly being added to the same crowded frequency spectrum. As a result, interference is inevitable.

The issue here is coexistence—the ability of wireless equipment to operate in the presence of other equipment using dissimilar operating protocols or standards. When two pieces of wireless equipment are near one another, and operating on the same or a close frequency, they will both be affected. The densest spectrum utilization is in the license-free “ISM” bands at 2.4 and 5 GHz. Bluetooth devices, microwave ovens, and wireless surveillance cameras are other examples of wireless equipment that can cause interference. Licensed spectrum such as cellular phone bands are more tightly controlled, but even their transmissions can affect users of nearby frequency bands.

Device coexistence is essential for stable, reliable communications in the IoT. Unfortunately, it’s very hard to ensure. It’s not something you can know with any level of confidence, without taking appropriate action during the design process.

The single most important action you can take is to perform coexistence test. The testing helps you determine your device’s tolerance to other radio signals and ensure that a certain level of device operation is possible, even in the presence of alternate radio protocols. It can be performed using one of four methods: conducted/wireless test, multiple chamber/hybrid test, radiated-anechoic chamber (RAC) test, or radiated open environment (ROE) test. Which method you choose depends on practical considerations like whether you have access to an external antenna connection on your device under test.

With coexistence test, you can quickly locate and identify interference impacting your device so that you can mitigate its impact before the device enters the real world. Once in consumers hands, any unexpected behavior from your device can erode consumer confidence, severely degrade your brand and even result in a potentially costly recall. Remember, it's ALWAYS cheaper and easier to solve coexistence issues in the lab BEFORE they become a problem in the field.

If you are developing an IoT device or system, optimizing its performance in the lab is just one step to making it a success. The other crucial step is making sure it can survive and thrive in the real world, regardless of how many other IoT devices may be operating in its vicinity. Coexistence test gives you a way to do just that.

If you want to learn more about how to design a coexistence test for your IoT device, or pick up some tips on practical measurement techniques that can simplify your coexistence test process, check out the free webinar: IoT Device Coexistence Challenges - So Many Transmitters!