Proximity Detection with RFID: A Step Toward the Internet of Things In the Internet of Things (IoT), things will be able to sense, communicate, and interact. They will also exchange data and information and locate themselves and other things that surround them. To interact, the things must recognize that they’re in proximity of other things. It’s anticipated that a widespread component of the IoT will be passive RFID tags, because they’re inexpensive and provide automatic identification. However, passive RFID tags can’t perform complex operations, such as proximity detection and localization. In this article, the authors describe existing problems with current RFIDsystems and survey potential solutions for proximity detection. They then present a new RFID device, called “Sense-a-Tag” (ST), that can passively detect and decode backscatter signals from tags in its proximity. The authors show that when STs are added to a standard RFID system, the problems of proximity detection in the IoT with RFID tags can readily be resolved. They demonstrate the feasibility of an ST-based RFID system through proximity detection experiments.