licenseexempt

License-exempt refers to activities or devices that may operate without a license from the appropriate government authority because they comply with predefined technical rules that authorize unlicensed use of specific spectrum or services. The concept is used primarily in wireless communications, broadcasting, and some sensor networks. In practice, license-exempt operations are constrained to designated bands and must tolerate or avoid causing interference to licensed users.

In wireless communications, widely used license-exempt bands include various ISM bands around 2.4 GHz and 5 GHz, as well as short-range, consumer-oriented frequencies. Devices such as Wi-Fi routers, Bluetooth peripherals, cordless phones, baby monitors, and many IoT sensors typically operate under license-exempt rules. The rules are implemented differently by jurisdiction; in the United States, Part 15 of the Federal Communications Commission governs many license-exempt devices, while in Europe and other regions, corresponding regulations under ETSI or national authorities apply.

Common requirements for license-exempt devices include limits on transmission power, restrictions on antenna gain, and limits on conducted and radiated emissions. Operators must accept any interference and must not cause harmful interference to licensed services. Some jurisdictions require testing and labeling, with devices bearing compliance marks or identifiers.

Advantages of license-exempt regimes include lower entry barriers, reduced regulatory costs, and faster product introduction. Limitations include greater potential for interference, spectrum crowding, and the possibility of changes in rules or enforcement. The concept varies by country, making compliance and testing essential for manufacturers and users.