FCC Denies Wireless-Microphone Makers’ Plea for Vacant Spectrum Availability

The action also spotlights new WMAS spectrum-efficient wireless technology

In an Order on Reconsideration issued on May 11, the Federal Communications Commission denied a request from microphone-systems manufacturers Sennheiser and Shure to sustain a vacant channel in the TV bands reserved for wireless-microphone use. That channel was part of the FCC’s landmark 2015 Notice of Proposed Rulemaking intended to outline the post-auction landscape for wireless microphones.

In issuing the 2015 Notice, the FCC acknowledged that there would be fewer unused television channels in the TV bands post auction and after spectrum repacking, but it expected that at least one channel in the UHF band would be available for shared use by unlicensed white-space devices or wireless microphones. The matter engendered a lengthy legal and technical back-and-forth. In the ensuing debate, broadcasters argued against the idea, contending that the FCC’s 2015 proposal would limit future expansion and innovation potential for full-power TV stations. Broadcasters also said the proposal would require “novel engineering studies” that would be expensive and time-consuming, particularly for smaller broadcasters.

In responding to the most recent ruling, wireless-microphone users and those who make that equipment contended that the provisions for those wireless devices were necessary, “expressing strong support for the important functions performed by wireless microphones and support for the designation of one UHF channel for wireless-microphone use,” as per the Order On Reconsideration. “Issues are identified regarding the adequacy of higher-frequency alternatives to a vacant UHF channel, as well as the past costs imposed on wireless-microphone users when spectrum availability was moved.”

The National Association of Broadcasters, on the other hand, had argued that the preservation of at least one vacant channel on a nationwide basis “is no longer achievable” and that it was “entirely appropriate” to close this proceeding in light of the burdens to broadcasters.

Both Shure and Sennheiser filed replies to NAB’s opposition, with Shure suggesting that a vacant channel for wireless microphones be preserved in every market where at least two vacant channels are available. Sennheiser also filed an ex parte disagreeing with the commission’s assertion in the Termination Order that there is currently no vacant 6-MHz channel in multiple major metropolitan areas and including information purporting to identify a vacant channel suitable for wireless microphones used in nearly every top-50 market.

Ultimately, the FCC determined, “We find that adoption of the rules proposed in the 2015 NPRM would not strike the most reasonable balance that would best serve the public interest. … We make this determination in light of other actions taken by the Commission since the 2015 NPRM that will support wireless-microphone users and the burdens that the proposal would impose on broadcasters. Because we agree that the totality of these circumstances support the findings in the Termination Order, we reject the Petitioners’ claim that the Commission’s action was arbitrary and capricious.”

However, the commission added, “Although we have concluded that we should not proceed with the proposals in this docket, the Commission is committed to supporting white-space devices and wireless microphones and has pursued, and continues to pursue, avenues to ensure adequate spectrum availability for the important services they provide.”

In fact, as part of its statement, the FCC said it has continued to pursue paths to support access to spectrum by wireless-microphone users, citing a 2021 Notice of Proposed Rulemaking for the operation of Part 74 low-power auxiliary station (LPAS) devices to permit a recently developed type of wireless-microphone system, referred to as a Wireless Multi-Channel Audio System (WMAS), to operate in the TV bands and other LPAS frequency bands on a licensed basis. The emerging technology, already permitted in Europe under the applicable European Telecommunications Standards Institute (ETSI) standards, “would enable more wireless microphones to operate in the spectrum available for wireless-microphone operations, and thus advances an important Commission goal of promoting efficient spectrum use.”

The technology, which would enable more microphones per megahertz of spectrum, is currently under consideration by the FCC. A Notice of Proposed Rulemaking, issued in April 2021, sought public comment on allowing WMAS on a licensed basis in frequency bands where wireless microphones already are authorized, including the TV bands, the 600 MHz duplex gap, and in portions of the 900 MHz, 1.4 GHz, and 7 GHz bands.

By digitally combining multiple signals, WMAS — promoted by Sennheiser, Shure, and other manufacturers — allows microphones to operate using wider-bandwidth channels than currently allowed. It will be “a game-changer,” says Joe Ciaudelli, director, spectrum and innovation, Sennheiser. “[It] offers an easier and more flexible workflow and provides greater protection to other services that share the same frequency band. We applaud that the commission seems to be entertaining our Petition for Rulemaking to authorize WMAS, but it’s only part of the equation in addressing the needs of content-creation professionals. [As with] any wireless device, access to suitable spectrum is required. Sennheiser will continue to work with the commission on developing long-term solutions.”

Additionally, the commission recently upheld slightly modified requirements intended to protect licensed wireless-microphone users from interference caused by white-space devices. Specifically, it states that these users now “have immediate and exclusive access to a 4-MHz portion of the 600 MHz duplex gap and can also use a 2-MHz portion of the 600 MHz guard band where white space devices are not permitted to operate.” In addition, the FCC says, “These wireless-microphone operators potentially could [also] make use of the 6 MHz of the 600 MHz duplex gap available for unlicensed operations if white-space devices are not operating at that location.”

It further notes that many parts of the country may have vacant TV channels that are not in use by white-space devices and may be available for wireless microphones.

Manufacturers Respond

In response, the wireless manufacturers said they will continue their pursuit of appropriate spectrum.

“Shure takes note of the commission’s decision and will continue to work diligently with the commission and other stakeholders to ensure adequate spectrum is available for the important services that wireless microphones provide,” the company said in a written response to a query from SVG. “Wireless microphones continue to play an essential role in supporting productions for a number of facets of American life, culture, and the economy. Beyond their traditional role in broadcasting and film production, wireless microphones support productions in a wide range of sectors, including news reporting, theater, music, sports, worship, civic events, transportation infrastructure, and education. Reliable, interference-free, low-latency operation is the essential function of professional wireless-microphone systems.”

Sennheiser’s Ciaudelli, wrote, “Sennheiser thanks the wide gamut of industry groups and audio-video professionals that wrote to the commission, establishing overwhelming support on the record for adequate spectrum resources for content creation and cultural enrichment. We will continue to work with the commission so that it comes to fully appreciate the indispensable contributions that wireless production tools provide to media creation as well as every echelon of daily American civic life and to develop solutions that will provide necessary resources for these tools to operate reliably and consistently in every situation.”