What is the difference between RFID and UWB, and what are the pros and cons of each?
Ultra-wideband (UWB) is a wireless communication protocol, similar to Bluetooth or Wi-Fi. There are active RFID tags that use UWB, and there are also Wi-Fi-based active RFID tags and Bluetooth beacons. The difference between Wi-Fi and Bluetooth and UWB is that UWB uses a higher frequency and involves multiple frequency bands rather than a single band.
The benefit of using multiple frequency bands is that you can overcome the issue of multipath, which is when radio waves bounce off walls, objects or the floor before reaching a receiver. If you have an active RFID tag that uses 433 MHz to broadcast, then the signal might bounce around and reach the receiver at a different time than a signal transmitted straight to the receiver. This multipath effect limits the location accuracy of a 433 MHz active RFID system to about 3 meters (9.8 feet).
I’m not an RF engineer, but I am told that UWB overcomes multipath by using a variety of frequency bands. This enables it to be much more precise in locating a tagged object. Typically, you can locate something with a UWB tag to within 10 centimeters (3.9 inches). The benefit of UWB is that it is highly accurate in locating a tagged object. The negative is that you must broadcast a signal, so tags are much more expensive than passive UHF RFID tags. In certain applications, UWB is ideal, while in others, it is overkill.
Apple has included a UWB radio chip in its iPhone 11 smartphone, which it plans to use this to automate tasks by precisely locating you via your phone. For example, if there were a UWB transceiver in your car, the doors could unlock automatically as you approached, or the trunk could pop open as you walked toward the back, since the vehicle would know your precise location. In your home, your television could turn on and go to your favorite channel when you walked into the TV room with your phone. In these applications, your phone would act as an active RFID tag using UWB to locate you. It might also be possible one day to install an active UWB system in your home that would enable you to quickly find your iPhone anywhere within the premises.
I hope this answers your question, and I hope to see you at RFID Journal LIVE! 2020, where you can learn more about these technologies.
—Mark Roberti, Founder and Editor, RFID Journal