FCC Pops Lid off Spectrum High End

The Federal Communications Commission ("FCC" or the "Commission") has opened a new frontier in the amount of spectrum available for unlicensed and experimental operations, adopting rules covering frequencies between 95 GHz and 3 THz (3,000 GHz).

Once upon a time, the world's techies thought that radio waves at extremely high frequencies (i.e., with very short wavelengths) could not travel further than an adept child could reach with a bean shooter, so these bands would never be useful. But no more - over the past few decades, technology has advanced beyond most expectations. We now have satellite communications, Wi-Fi, microwave links, self-parking cars, and all sorts of other stuff operating at ever-higher frequencies, which we first measured in kilohertz (1,000 cycles per second) in the early days of AM radio, then in Megahertz (1,000 kHz), next in Gigahertz (1,000 MHz), and now shooting up to Terahertz (1,000 GHz, or 1 trillion cycles per second).

While the FCC's Table of Frequency Allocations includes listings above 95 GHz, the FCC has not until now had rules providing for regular use of those bands apart from exotica like satellites for earth and space exploration; radio astronomy; Amateur Radio; some industrial and medical devices that use radiofrequency energy but do not communicate information; and of course government operations, some which are secret. It has now provided for regular unlicensed operation in four specific bands totaling 21.2 GHz and for a new class of experimental license that may operate anywhere in the band 95 MHz to 3 THz, subject to protecting existing operations. These are only first steps; decisions about requests for regular licensing have been deferred for now but remain on the table for future consideration.

Those seeking to operate on an unlicensed basis may soon proceed to get equipment certified (a prerequisite to marketing to the public) and to deploy, although they will have to wait for the new rules to be published in the Federal Register and approved by the Office of Management and Budget (OMB). Note that equipment that operates above 95 GHz must not be designed to enable operation below that frequency, although it may be based on designs developed for lower bands.

Unlicensed devices may operate only in the bands 116-123, 174.8-182, 185-190, and 244-246 GHz. Power limits will be 40 dBm EIRP average, 43 dBm peak, except that outdoor point-to-point systems with highly directional antennas may operate at up to 83 dBm average, 85 dBm peak. Devices with a bandwidth of less than 100 MHz will have to reduce power to avoid a high concentration of energy in a narrow band. Out of band emissions will be limited to 90 picowatts per square centimeter at 3 meters, the same as at 57-71 GHz, but measured to the lower of the third harmonic or 750 GHz.

Inventors and researchers who want to see what new technologies they can come up with that do not qualify for other kinds of licensing may apply for a new type of experimental license, called a "Spectrum Horizons" license, which will be valid for 10 years and will provide some flexibility to involve the public in trials. Eligibility will be restricted to qualified entities, including colleges and universities with accredited graduate engineering research programs, research laboratories, hospitals, and health care institutions, manufacturers of radiofrequency (RF) equipment, and manufacturers that integrate RF modules into other products. Spectrum Horizons experimental licenses will not be renewable, since the FCC's focus is on developing products for the marketplace, and 10 years should be enough to figure out whether an idea will make it to the marketplace or should be abandoned. The experimental report required at the end of the term of a conventional experimental license will not be required for Spectrum Horizons licenses, but an interim progress report will be required at the end of five years.

Prospective experimenters had hoped that the FCC would grant Spectrum Horizons licenses for the entire 95 GHz-3 THz band without geographic restrictions, but no such luck. While no specific frequency bands have been placed flatly off limits, Spectrum Horizons applications, like traditional experimental applications, will continue to be coordinated by the FCC with federal agencies, which historically have declined to agree to operation in certain bands and/or at certain locations and generally have not provided an explanation to the rejected applicant. Applicants seeking to operate in bands that have protected existing operations, particularly passive activities (like listening for signals from alien civilizations or searching for origins of the universe) will have to explain why those bands have unique characteristics of value to their experiment and why experimentation cannot be conducted in other bands. Applications proposing very wide geographic areas will also require an explanation and may have an increased chance of rejection or limitation after the coordination process.

Spectrum Horizons applicants will be able to request confidential or proprietary treatment for some aspects of their applications; but the basic characteristics of proposed operations, including frequencies, types of emissions, power, and geographic location, will be available to the public on the FCC's website.

Holders of Spectrum Horizons experimental licenses will have greater flexibility than traditional experimental licensees to sell equipment and to involve the public in trials. However, any equipment provided to any person or entity other than the license holder will have to be labeled with a warning (using language prescribed by the FCC) that operation may be terminated at any time. The licensee must also retain control over the equipment, marking each unit with a unique serial number that can be tracked, and retaining the ability to retrieve all equipment or to disable it remotely when authorized experimental use ends.

If you see potential in the new spectrum frontier, which may prove useful for super-fast broadband connections over short distances if not navigating flying carpets and other new transportation systems, now is the time to think about getting a license to crank up a research program.