Sam Benzacar, President – Anatech Electronics
Although manufacturers, analysts, and the media have proclaimed for years that there soon would be “billions and billions” of IoT devices in operation, it seemed hard to believe. Other than Nest thermostats, LED lighting, and a few other products there was little tangible evidence of IoT anywhere. That’s not true anymore, as an enormous number of these tiny devices have already been deployed, many of which unseen as they exist within industrial applications, smart water and electricity meters, and many other places.
So, IoT is no longer coming, it’s here, and with it the potential for interference. The industry says they’ve found solutions, but as a manufacturer of RF and microwave filters for more than 25 years, I’ve heard that many times before. In reality, there is always the potential for interference no matter how many steps are taken to prevent it. IoT is so all-encompassing and uses so many different communication protocols operating on just a few frequencies, that interference seems inevitable.
If you have been following IoT you’ve no doubt noticed that there are at least seven prominent solutions vying to become the kings of short-range connectivity. They are technologically diverse, mostly incompatible, and like all technologies have strengths and weaknesses. This isn’t likely to be a winner-take-all scenario as it’s unlikely that only one solution will own the market. That means there will be multiple solutions operating in the same environment, each with different characteristics, and often very near each other in frequency. It’s a situation ripe for interference.
Moving beyond device-to-device communication are the solutions designed to take the aggregated data from these connected sensors to a gateway and then on to the Internet for cloud-based processing and storage. In this case there are fewer competitors, primarily cellular networks using their newly-minted narrowband, low-data-rate transmission schemes such as NB-IoT, and Low-Power Wireless Area Network (LPWAN) solutions like Sigfox, LoRaWAN, Ingenu, and others. This is arguably a more controlled environment as wireless networks have been dealing with interference for decades. That said, the LPWAN providers add new signals into the environment, and even though they are taking great pains to mitigate interference, the potential still exists.
And I haven’t even mentioned autonomous vehicles that contrary to what everyone believed only a few years ago are likely to appear on the road sooner than expected. To have the most precise situational awareness, every vehicle will be equipped with at least one of the proposed communication solutions. The incumbent solution is called Dedicated Short-Range Communications (DSRC) that was conceived in the 1990s and made an IEEE standard (802.11p) in 2009. It provides 75 MHz of dedicated spectrum around 5.9 GHz and is designed to provide the communications requirements for vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and even vehicle-to-pedestrian (V2P) communication, collectively called V2x.
It’s the de facto choice but it’s been a long time since DSRC was created and the cellular industry is attempting to cash in, offering its networks for the same purpose. They may not succeed in the U.S. at least in the short term because the auto industry has spent billions of dollars on DSRC and has no interest in making a change. Nevertheless, many new vehicles are already equipped with what are misleadingly called “4G Wi-Fi” hotspots, Wi-Fi is likely play some role in vehicle autonomy, and when combined with DSRC (or cellular) connectivity, they add another interference challenge to the mix.
Taken together, the signals generated by IoT devices represent entirely new applications rather than modifications to existing ones, which means the airwaves are about to become even more populated than they are today. The result is extremely dense signal environments concentrated in a few regions of the spectrum. Unfortunately, as has long been the case in cellular, defense, broadcast, and other sectors, operators typically don’t know if, how much, and where interference will appear until the networks are deployed. Nor can they know whether harmonics and spurious signals from their own as well as other services will affect operation.
When (not if) IoT interference rears its head, the solution will be provided by RF and microwave filters, which remain the most viable tools for mitigating interference in deployed systems. They’ve saved countless base stations, radars, and assorted other systems faced with errant signals from being degraded or rendered useless. Now they’ll be called on to deliver the same benefits to a new family of systems facing a very old menace.
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