Wireless Mic NPRM Expected to Get 4-0 Vote -- With Tweaks
The NPRM proposing to allow the use of new wireless multichannel audio system (WMAS) technology by wireless mics is expected to be approved 4-0 Thursday, though a few tweaks are possible based on ex parte filings, FCC officials told us. The NPRM hasn’t faced opposition since circulation by acting Chairwoman Jessica Rosenworcel. A few questions were raised on implications for the 6 GHz band, which the FCC reallocated for Wi-Fi a year ago. An order terminating the 800 MHz rebanding proceeding is also expected to get unanimous approval.
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The draft proposes to allow WMAS in licensed frequencies already available for use by mics in TV bands. The technical rules would be based on those for low-power auxiliary station devices in Part 74. The licensed bands included are the 653-657 MHz segment of the 600 MHz duplex gap and 941.5-944, 944-952, 952.850-956.250, 956.45-959.85, 1435-1525, 6875-6900 and 7100-7125 MHz.
The docket on the wireless mic NPRM, 21-115, has been relatively sleepy. Only Microsoft and New America’s Open Technology Institute reported calls to raise questions.
A Microsoft representative met with aides to Rosenworcel and Commissioner Brendan Carr, saying the company appreciated that the proposal takes into account the potential impact on white space devices. In the Carr meeting, Microsoft raised questions about the power levels the FCC proposes to allow. A Microsoft spokesperson declined further comment Tuesday. The software maker was the only party to raise concerns on a 2018 petition by Sennheiser seeking an NPRM on the use of WMAS and other advanced technologies, but its concern was unlicensed mics (see 1901020013). Microsoft backed use of the white spaces for rural broadband through its Airband initiative (see 1812110043).
“For WMAS systems operating in the 6 and 7 GHz bands, under the proposed spectral efficiency and channel size, this means there could be up to 18 Watts or 42.55 dBm in a 6 MHz WMAS channel,” Microsoft said last week: The NPRM doesn't discuss “unique coordination requirements at these potential power levels.” That may partly be because low-power auxiliary service licenses there “remain largely hypothetical,” Microsoft said: “The regulation authorizing Part 74 LPAS microphones to operate in the 6875-6900 MHz and 7100-7125 MHz frequency ranges went into effect in November 2015 and there doesn’t seem to be much, if any, deployments.”
Michael Calabrese, director of the Wireless Future Program at New America, spoke with an aide to Commissioner Geoffrey Starks. Calabrese said the FCC “should more explicitly seek comment on the interaction between potential Part 74 WMAS operations” at 6.875–7.125 GHz and “the newly-authorized allocation of that same spectrum for unlicensed use.”
“Requesting comment and data on the impact of more intensive microphone use on newly authorized Wi-Fi use and innovation in the upper 6 GHz band should be noncontroversial,” Calabrese told us: “Because robust sharing of the band for next-generation W-Fi has been a bipartisan priority at the commission, we are hopeful the NPRM will invite technical input and make sure there are not unexpected problems down the road, when tens of millions of consumers are relying on very-low-power wearables and other portable devices.”
Wireless mic makers didn’t report meetings at the FCC on the draft NPRM and declined comment. Commissioners unanimously approved revised TV white spaces rules in October, which had been sought by Microsoft (see 2010270034).
“We applaud the commission for considering to modernize the technical requirements for professional wireless microphones" to usher in WMAS, said Joe Ciaudelli, Sennheiser director-spectrum and innovation. “This revolutionary technology fulfills the commission’s goal of improved spectrum efficiency, allowing more audio links to be transmitted within a limited bandwidth, such as a vacant 6 MHz TV channel. It also provides the operator with the flexibility to fine-tune the system’s critical parameters, such as audio fidelity, transmission robustness, link density and latency."
Adopting use of “the well-known and understood Longley-Rice Irregular Terrain Model” in the white spaces would ensure that “broadcast television signals are adequately protected from adjacent TV white space operations,” emailed Louis Peraertz, Wireless ISP Association vice president-policy: That model bridges “digital divides by identifying more areas where TV white space operations can help provide broadband service.”
A second order terminating the 800 MHz rebanding process, which started in 2004, hasn’t been controversial, with no meetings reported in docket 02-55 since the order circulated. T-Mobile declined comment prior to the commissioner vote. The company previously bought Sprint, which was involved in the rebanding.