One of the biggest challenges for the internet of things is batteries. As in, to communicate, sensors need them. That might be fine when you have one sensor monitoring the moisture in your garden soil, but it quickly becomes daunting to think about changing out batteries on 20 sensors in your home — or 2,000 along a stretch of roadway for a connected city.
That’s why a communications technique developed by researchers at the University of Washington is so interesting. The researchers have found a way to use existing radio waves (from cellular, TV or existing Wi-Fi networks) to bounce messages from one device to another without requiring a power source. They call it ambient backscatter, and liken it to Morse code.
I call it a great way to send minute bits of information and enable a more sensor-rich environment. The caveat here is that the data rates here are tiny and can only travel short distances — it can deliver data at about 1 kilobit per second over 2.5 feet outdoors (1.5 feet indoors). That’s enough to deliver a text message in a reasonable time frame, but the average web site at 1.25 megabytes would take almost 3 hours.
Below is a video explaining how it works, but basically absorbing available frequencies results in a 0 bit, while reflecting RF generates a 1-bit, creating a string of zeros and ones that a computer can read. The available RF is used both to transmit information, but also to power it, which is why the data transmitted is pretty small.
Research like this also could open new ways to think about powering devices in the internet things. You could embed ordinary devices with microcontrollers and radios but no power source. When you need to communicate with the object, say via a smartphone, your device would transmit not only data to the object but the power it needs to crunch that data. I’d love to see this commercialized.