FCC Approves Regulatory Changes for More-Powerful WMAS Systems in U.S.

The technology enables more-efficient use of spectrum for unlicensed users

A regulation change approved by the Federal Communication Commission (FCC) permits operation and deployment of Wireless Multichannel Audio Systems (WMAS) in the U.S. The Feb. 15 FCC Report & Order adopted new rules to allow the new, more spectrally efficient wireless-microphone technology to operate here.

WMAS uses spectrum more efficiently than currently available narrowband microphones, which means that more microphones can be used without more bandwidth being allocated. The new rules will permit WMAS to operate on a licensed or unlicensed basis, while preserving the existing spectrum rights of users sharing the frequencies, which are heavily used by broadcasters as well as by theaters and music venues, corporate events, and webcasting.

The new rules will allow WMAS to operate in the broadcast-TV bands and in the 600 MHz duplex gap on both a licensed and unlicensed basis and in other Part 74 LPAS frequency bands on a licensed basis. WMAS will enable more wireless microphones to operate in the available spectrum (that is, more microphones per megahertz of spectrum), providing additional options when more microphones are needed.

The rules do not alter existing spectrum rights or expectations regarding spectrum access and availability related to other authorized users’ sharing the frequency bands with wireless-microphone operations (including, for example, broadcast licensees, Wi-Fi, and white-space device users).

Manufacturers Hail Ruling

Leading wireless-microphone manufacturers Sennheiser and Shure welcome the finding.

Sennheiser’s Dr. Andreas Wilzeck: “We applaud the FCC for its adoption of WMAS technology. It is an important signal for the harmonization of regulatory conditions for these important global applications.”

Sennheiser, a major proponent of WMAS technology, describes it in a statement as “an advanced wireless-microphone technology designed to meet the challenges of highly demanding live performance and studio applications.”

Says Dr. Andreas Wilzeck, head of spectrum policy and standards, Sennheiser, “We applaud the FCC for its adoption of WMAS technology. In particular, the alignment with EN 300 422, which was developed by ETSI [European Telecommunications Standards Institute], is a milestone for manufacturers and users of wireless microphones and in-ear monitors (IEMs). It is an important signal for the harmonization of regulatory conditions for these important global applications.”

Since WMAS uses a single RF carrier, the possibility of intermodulation artifacts is eliminated, according to Sennheiser. For the first time, the company adds, in-ear monitor channels will be able to use, in parallel, the same block of RF spectrum as wireless microphones, further enhancing spectral efficiency.

Sennheiser’s Joe Ciaudelli: “WMAS will revolutionize the professional-audio industry as well as fulfill the commission’s goals of greater spectrum efficiency and sharing compatibility.”

Such capability would encourage the use of wireless transmitters for both microphones and IFB earpieces used, for instance, for wiring athletes for two-way conversations on the field of play.

“For years,” says Joe Ciaudelli, director, spectrum and innovation, Sennheiser, “customers have been asking for a single pack that is both a transmitter and an in-ear monitor receiver. WMAS will revolutionize the professional-audio industry as well as fulfill the commission’s goals of greater spectrum efficiency and sharing compatibility.”

Shure, which has been active in FCC proceedings over the past few years, advocating on behalf of a wide array of customers who rely on wireless microphones, says that it asked the FCC for unlicensed WMAS with higher power and that the agency agreed. The company’s statement says, “Shure believes the need for 100-mW unlicensed power is important because it allows providers to minimize occupied spectrum while remaining equivalent in link performance to narrowband.”

Shure’s Prakash Moorut: “Allowing unlicensed WMAS with power up to 100 mW is a big benefit for many individuals, organizations, and small businesses.”

Further, the statement contends, WMAS decreases total power spectral density (PSD) when audio-channel efficiency is met and aligns with recent WMAS updates within ETSI.”

Says Prakash Moorut, global head of spectrum and regulatory affairs, Shure, “This is a great decision by the FCC, to provide many microphone users across America with added flexibility. Allowing unlicensed WMAS with power up to 100 mW — twice the power allowed for narrowband wireless microphones — is a big benefit for many individuals, organizations, and small businesses.”

Tom Kundmann, VP, professional wireless, Shure, highlights the potential of wideband wireless in the UHF and other bands: “This technology will provide our customers with innovative product solutions. Our team is actively working on improving spectral efficiency, scalability of audio services, and simplifying deployment.”

‘A Spectrum Win-Win’

Compared with conventional wireless-microphone systems, WMAS offers higher spectral efficiency — the ability to transmit more audio channels within a limited block of RF spectrum — as well as greater interference protection for other wireless services sharing the same spectrum.

In a statement during the Open Commission Meeting, FCC Chairwoman Jessica Rosenworcel pointed out, “[W]hen a new technology comes along with the potential to improve the efficiency of wireless-microphone operations, we’re going to take a second look. That’s why, a few years ago, we issued a rulemaking to explore this new type of technology known as Multichannel Wireless Audio Systems, or WMAS, [which] can significantly improve the efficiency of wireless-microphone operations. … That’s a spectrum win-win.”