Spectrum Faces Its Next Challenge as FCC Allocates 6-GHZ Range for Wi-Fi 6
FCC makes 6-GHZ range available for unlicensed use by consumer mobile devices
Just when you thought it was safe to back into the wireless waters in the wake of the reallocation of the 600-MHz range of spectrum, a new front appears to be opening in the relentless wars between professional wireless systems users and consumer mobile-wireless demands.
In late April, the FCC announced the adoption of rules that make 1,200 megahertz of spectrum in the 6-GHz band (5.925–7.125 GHz) available for unlicensed use, intended as a foundation for Wi-Fi 6, the next generation of Wi-Fi.
In announcing the repurposing of this spectrum, which is currently populated by microwave services that are used to support utilities, public safety, and wireless backhaul, the FCC stated in a press release that “Wi-Fi 6 will be over two-and-a-half times faster than the current standard and will offer better performance for American consumers. Opening the 6 GHz band for unlicensed use will also increase the amount of spectrum available for Wi-Fi by nearly a factor of five and help improve rural connectivity.”
Specifically, the FCC’s Report and Order authorizes indoor low-power operations across the entire 1,200-MHz slice and standard-power devices in 850 megahertz in the 6 GHz band. An automated frequency-coordination system will prevent standard power access points from operating where they could cause interference to incumbent services.”
However, that’s wishful thinking, according to some in the professional wireless sector, including Jackie Green, Director at RF consultancy Nexonic Design. Asked if the FCC decision to open up the 6-GHz band to unlicensed Wi-Fi and other wireless users is a problem for broadcast users, she replied without hesitation, “It sure is.”
Citing studies and comments by pro wireless users on NAB and other message boards, Green enumerated the areas that opening this area of spectrum will potentially negatively affect.
“This is problem for cameras, [which] have already moved due to Wi-Fi and now have nowhere left to go,” she explains. “[Also], despite opening portions of the 6785-7125GHz spectrum for Part 74 licensed wireless microphones, the FCC is now chipping away at wireless microphones’ ability to operate by adding Wi-Fi to this spectrum. This decision comes even before the July 13, 2020 cut-off date of the post-auction transition period, showing little concern for the difficulty the loss of spectrum causes Part 74 wireless users. There is really no solid proof that this won’t be a problem for fixed services, satellite and [broadcast auxiliary service (BAS) — an RF channel typically used for internal-use backhaul] users, even if there is an [automated frequency coordinator]. The studies, which were referenced to determine interference, were extremely Wi-Fi biased. That combined with minimal [out-of-band emissions] restriction will equal trouble. There are existing… reports of Wi-Fi in other bands interfering with fixed services and broadcast equipment.”
That interference will manifest as “death by a thousand knife cuts,” according to Dane Ericksen, Chairman of Engineers for the Integrity of Broadcast Auxiliary Services Spectrum (EIBASS), cited in an article in Cell Tower News, an industry trade publication, making it “… difficult, if not impossible, to track down interference to licensed users” in the band. The FCC’s decision, he continued, “will trash the upper 6 GHz band like Wi-Fi trashed the 2.4-GHz TV BAS (Broadcast Auxiliary Spectrum) band, making TV BAS Channels A8 (2450-2467 MHz) and A9 (2467-2483.5 MHz) almost useless due to the 10 to 20 dB higher noise floor compared to grandfathered TV BAS Channel A10 (2483.5-2500 MHz), where Part 15 Wi-Fi is not allowed.”
Those concerns apparently don’t offset the benefits the FCC predicts for consumer wireless devices as a result. Calling the move “a massive 1,200 megahertz test bed for innovators and innovation,” FCC Chairman Ajit Pai said in a statement, “By doing this, we are effectively increasing the amount of mid-band spectrum available for Wi-Fi by almost a factor of five. This will be a huge benefit to consumers and innovators across the nation.”
The decision was unanimous, including positive votes by the Commission’s to Democratic-appointed members. One of them, Jessica Rosenworcel, noted that the R&O does include several changes she pressed for, including clarifying power levels for client devices, seeking comment on opportunities for portable devices, and the right power levels for very-low-power devices. “As a result, this effort has my support,” she said, noting the move makes possible Wi-Fi with 160 megahertz-wide channels that can offer gigabit speeds.
Unsurprisingly, the decisions also has the backing of companies and organizations in the wireless consumer–device space, including Apple, Broadcom Corp., Cisco Systems, Facebook, Google, Intel, Microsoft, Qualcomm, CTIA and WISPA.
However, Green counters that the range and power levels specified by the FCC present interference problems, noting that European Union regulations in the same RF range must be stay below 6.425 GHz.
“The FCC is suggesting low-power WiFi, but at the levels they are suggesting it will interfere with wireless microphones,” she asserts, citing studies in the EU and elsewhere. “The FCC will not require AFC for very-low-power operation (VLP), so Part 74 users won’t be able to register for protection from VLP devices, and instead these devices will have to LBT [listen before talk]. However, the studies done in the EU already showed that reliably detecting a wireless mic is not possible. Plus, Wi-Fi only has to check once every 24 hours.”
Green points out that the FCC is calling for a multi-stakeholder group to form to address co-existence, AFC use, and other methods to allow everything to work together.
“Broadcasters should be commenting, and they should be participating,” she says. “The R&O specifically mentions using this group if certain additional best practices need to be addressed,” citing pg. 179 of the R&O document.
Comments are still open on certain aspects of the reallocation. Specifically, the Further Notice of Proposed Rulemaking seeks comment on a proposal to permit very low-power devices to operate across the 6-GHz band to support high data-rate applications including high-performance, wearable, augmented-reality and virtual-reality devices. The notice also seeks comment on increasing the power at which low-power indoor access points may operate.
The 6-GHz encroachment also comes at a time when licensed professional wireless users complain that protections putatively built into recent spectrum reallocations lack oversight and enforcement. Technical trade organizations, such as the NAB, SBE and the National Spectrum Management Association, which represents microwave radio/wireless and satellite frequency coordinators, licensees, manufacturers and regulators have also expressed concerns with the FCC’s decision, as have other entities, including AT&T.
The consensus, however, is that the momentum behind reallocating spectrum to consumer mobile applications is inexorable. Perhaps critics of the move may find some common ground with a somewhat larger ally also concerned with looming interference: the Department of Defense. They’re battling with the FCC over its recent unanimous decision to allow Ligado Networks to build a low-power 5G network, which the DoD contends will interfere with GPS signals vital to national security.
“With this on top of revisiting the white spaces ruling,” says Green, “the regulators just keep hammering away against the broadcasters.”