More Agreement on TV White Spaces


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Reaction has been mixed to a recent request from Microsoft to the FCC to issue a Further Notice of Proposed Rulemaking to “improve” the agency’s TV White Spaces (TVWS) rules. TVWS are the unlicensed spectrum blocks between television channels. Microsoft says the suggestions stem from seven years of on the ground experience with its Airband Initiative, which uses White Spaces and other distribution methods in partnerships with ISPs, to provide economical broadband in rural areas.

The Wireless Internet Service Providers Association (WISPA), told the FCC this week, Microsoft’s proposed changes would enable TVWS spectrum to be more efficiently deployed for rural broadband access. WISP members use unlicensed spectrum to deliver high-speed broadband services to four million mostly rural, users. 

In particular, WISPA supports Microsoft’s call to: Permit fixed devices to operate at higher maximum power in less congested areas; permit use of spectrum adjacent to TV broadcast channels at power levels greater than 40 mW; and allow TV white space devices to transmit from a height above average terrain (HAAT) of up to 500 meters, subject to coordination for operations above 250 meters HAAT. WISPA also asked the FCC to invite comment on a proposal to allow greater flexibility to use sectorized antennas.  

“These changes would increase the range and capacity of TVWS networks, boosting investment in the development and deployment of new broadband solutions for rural Americans,” stated WISPA President/CEO Claude Aiken. “These proposals, and related technical changes WISPA asked the FCC to consider, will help put this still fallow resource into productive use, providing more broadband quickly and cost-effectively.”

In contrast, the NAB previously criticized Microsoft’s TVWS plan, saying it would interfere with licensed TV channels. But after several months of talks, the broadcaster trade lobby told the Commission it agrees with some of Microsoft’s proposals, Inside Towers reported.

This week, the NAB told the FCC it appreciates, “the constructive approach” Microsoft has taken in pursuing TVWS changes. Rather than proceed unilaterally with expansive requests to fundamentally change the ground rules of TVWS operations, Microsoft has sought to limit its petition to a narrow set of five asks, four of which NAB is able to support.

First, Microsoft proposes higher radiated power limits in rural areas. In particular, Microsoft proposes to increase the limit on EIRP from 40 dBm to 42 dBm in less congested areas. To protect broadcast operations, Microsoft proposes increased separation distances consistent with the methodology set forth in section 15.712 of the Commission’s rules. “Particularly given the Commission’s recent action to require automatic geolocation for TVWS devices, NAB believes it may be possible for TVWS devices to operate at the EIRP levels Microsoft proposes without causing harmful interference to existing licensed operations,” stated the association.

NAB supports Microsoft’s proposal to allow TVWS operations at higher antenna heights, specifically 500 meters height above average terrain, subject to restrictions. It also favors the proposal to allow geofenced fixed TVWS operations and fixed TVWS operations on movable platforms within geofenced areas, subject to certain protections.

NAB believes the agency should move forward with a Further Notice on the proposal for the to support the use of TVWS for narrowband Internet of Things (IoT) uses,  and on the other proposals to develop a record to confirm the proposals wouldn’t interfere with licensed broadcast use.

The big issue NAB disagrees with Microsoft on is higher-power operation on first-adjacent channels. “Microsoft bases this proposal in part on the assumptions that Next Gen TV receivers, will be more robust to adjacent-channel interference than the ATSC 1.0 receivers that the Commission’s previous analysis assumed, and/or that the need to upgrade DTV receivers as part of the Next Gen transition presents an opportunity to reduce their susceptibility to adjacent-channel interference,” says NAB.

The broadcast trade lobby says there’s no evidence Next Gen TV receivers will prove less susceptible to interference than existing receivers. And even if that assumption were true, rule changes based on more robust Next Gen receivers is “premature,” because the transition will likely take several years.

By Leslie Stimson, Inside Towers Washington Bureau Chief

June 12, 2019

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