Broadcast Engineers Predict BAS Havoc Over Planned 6 GHz Change


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UPDATE Broadcast engineers say the FCC’s decision last week to open up the entire 6 GHz band to unlicensed WiFi and other wireless uses will destroy the usability of those frequencies for electronic news gathering (ENG). The resulting interference will be “death by a thousand knife cuts” says Dane Ericksen, Chairman of Engineers for the Integrity of Broadcast Auxiliary Services Spectrum (EIBASS).

He tells Inside Towers the decision is going to cause “chronic and difficult, if not impossible, to track down interference to licensed users” in the band (5.925–7.125 GHz). That’s especially true for the 6.5 and 7 GHz TV pickup (ENG) receive sites, “which don’t transmit and are therefore the classic ‘hidden node’ problem for the listen-before-talk polite protocols the Commission insists will avoid any interference from up to 36 dBm EIRP wireless local area networks (WLANs),” he says. Just under a billion WLANs are proposed.

The change “will trash the upper 6 GHz band like WiFi 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 WiFi is not allowed,” Ericksen explains.  

“The most violated (and unenforced) of all FCC rules is Section 15.5(b), which states that a Part 15 device must not cause interference to any licensed service (e.g., Part 74 TV BAS ENG), and must accept any interference from licensed users,” adds the engineer, who’s also a consultant to Hammett & Edison.

He says the agency fails to enforce Section 15.5(b) with its now smaller Enforcement Bureau and only an FCC inspector has authority to conduct such enforcement. “A private, licensed user has no standing to do this, and lots of luck complaining to the FCC,” he concludes.

FCC Chairman Ajit Pai took several questions on the interference question after the meeting, and he reiterated the Commission believes it’s taking appropriate measures in the item to prevent harmful interference to incumbent licensees. Many groups support the change, including Apple, Broadcom Corporation, Cisco Systems, Hewlett Packard Enterprise, Facebook, Google, Intel, MediaTek, Microsoft, Qualcomm, CTIA and WISPA.

WISPA said after the vote, the FCC did the right thing. It noted unlicensed spectrum “is stressed to the max” and there’s been no major allocation of such spectrum in two decades. “This at a time when IoT, AI, smart home and other unlicensed-dependent technologies flood the marketplace; the deployment of 5G rapidly takes shape; and the Black Swan of the world’s new pandemic-induced, stay-at-home connectivity paradigm has put crushing demands on our networks and unlicensed ecosystem,” said WISPA after the vote.   

In addition to broadcast engineers, AT&T and utilities too, were disappointed with the vote. The telecom is concerned about interference to its microwave links critical to maintaining network infrastructure. AT&T agrees with broadcast engineers that once millions of unlicensed devices are used on the band, it will be impossible for the agency to find and remove specific devices causing interference.

The NAB, Society of Broadcast Engineers and National Spectrum Management Association, fought the changes as well. The NSMA represents microwave radio/wireless and satellite frequency coordinators, licensees, manufacturers and regulators.

By Leslie Stimson, Inside Towers Washington Bureau Chief

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