There have been many changes since I was a wireless engineer (still hold a commercial FCC license), and those changes have brought about new radio-based sensing/control systems, greatly expanding Industry 4.0 and IIoT opportunities. Since the FCC came into being in 1934, there are two operational choices for wireless communications in the U.S.: FCC licensed and license-free. Licensed operation includes, for example, commercial broadcasting, cellular/LTE services, aeronautical, ship-to-shore, emergency (public) services, amateur radio and SCADA (typically used by electric and water utilities). Unlicensed operation includes, e.g., citizens’ band radio (27 MHz/11 meters) and ISM (industrial, scientific and medical)) channels—and Wi-Fi and Bluetooth.
What’s the main difference between licensed and license-free operation? Licensed operation (like cellular 4G and 5G) means the channels are protected from overuse by the government. With unlicensed operation (e.g., Wi-Fi and Bluetooth channels), anyone can use any number of radio transmitters anywhere to relay data—or whatever—voice, video, machine data, etc., leading to interference and decreased usability.