What does it take to connect tens of billions of devices?
Among other things, transmit power control is a lynchpin feature of IoT-scale connectivity.

Blogs don’t start much nerdier than that kind of claim. But, good reader, fear not, for you shall not be disappointed for we shall explain how it is that not every network can connect billions of IoT devices.

First some definitions and explanation are in order. Transmit power control is the ability of an endpoint to adjust how “loudly” it broadcasts its signal enabling only the closest access point (AP) or so to hear it. Perhaps you didn’t realize that when endpoints broadcast their signal it isn’t just a single AP that can hear it. Other APs hear it too. This has a few very important implications. Each AP can only handle so much capacity, or said otherwise, can only handle so many signals that they can take in at once. So the more signals from distant endpoints that are heard by a given AP the less capacity it has to serve the endpoints that it really should be concerned with. Transmit power control drastically reduces this wasted capacity.

But the problem goes further than just wasted capacity. Without transmit power control, the network will eventually and catastrophically fail. Here’s why; a connectivity provider wishes to serve more endpoints and thus builds more APs. Great, more capacity right? Not without transmit power control. As more endpoints are added, they will all transmit at the same “volume” as before so that any new APs built still hear all the endpoints that were in the area prior to their being built. The new APs didn’t actually add any capacity! Endpoints will be heard by all the surrounding APs not just the closest AP and will crowd out the signals from endpoints that the AP should actually be serving.

Suddenly, adding new APs actually adds more capacity. YES. This kind of network can connect billions of IoT devices.

At some point each AP will reach capacity regardless of the number of APs being built because new APs do not reduce the load of other APs. Endpoints mindlessly yell as loud as they can regardless of what happens around them. The more endpoints added, the more self-interference the network experiences. And that’s when the catastrophic breakdown of such a network happens. It doesn’t just peter out, the thing just stops working reliably. In a strange irony, such a network’s success (more endpoints being served) is the cause of its own failure (APs ultimately overwhelmed).

Transmit power control solves all of this. As more endpoints are added and APs are added to serve them, the endpoints with transmit power control adjust their “volume” so that only those APs closest to them can hear them. Suddenly, adding new APs actually adds more capacity. YES. This kind of network can connect billions of IoT devices.

The Machine Network is the kind of network that can connect billions of devices. It can connect tens of billions of devices. RPMA, which is the Machine Network’s core technology, has transmit power control on its endpoints. Other IoT network technologies aiming to provide low power connectivity do not have transmit power control. And for that simple reason they will never be able to connect the tens of billions of devices the IoT will have. Right now, with no design changes needed whatsoever, the Machine Network has all the technology needed to support the kind of Internet of Things that has been envisioned for years.

To learn about many other reasons why RPMA enables the Machine Network to uniquely serve tens of billions of devices read our white paper, How RPMA Works.