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Federal Register / Vol. 86, No. 7 / Tuesday, January 12, 2021 / Rules and Regulations
separation distances from licensed wireless microphones are much shorter than those for broadcast TV and are in fact shorter than the distances over which HAAT is calculated 3 to 16
kilometers. Therefore, the Commission believes it is unnecessary to notify wireless microphone licensees of nearby white space devices operating at high HAAT since the HAAT is undefined at the wireless microphones location.
23. Antenna height above ground. The Commission previously increased the maximum permissible antenna height above ground from 30 meters to 100
meters in less congested areas in the White Spaces Order on Reconsideration 84 FR 34792, July 19, 2019. It took this action to improve wireless broadband service to Americans in rural and other underserved areas, and stated that a 100-meter antenna height above ground limit will benefit wireless broadband providers and users by permitting antennas to be mounted on towers or other structures at heights sufficient to clear intervening obstacles such as trees and hills that would attenuate the transmitted signal, thereby increasing the range at which the signal can be received.
24. In the NPRM, the Commission sought comment on whether to increase the antenna height above ground limit in addition to the HAAT limit, noting that antenna heights above ground and average terrain are directly related, in that any change to a devices antenna height above ground changes its HAAT
by the same amount. The Commission further noted that limiting the antenna height above ground may also limit the maximum achievable HAAT in areas where the terrain is flat since in those areas the HAAT will be approximately the same as, or not significantly higher than, the antenna height above ground.
This means that the antenna height above ground limit 30 or 100 meters may preclude white space device operators from taking advantage of a higher HAAT limit, or even the current 250-meter limit. The Commission sought comment on whether it should increase the antenna height above ground limit or remove it completely and rely only on HAAT since the separation distances from protected services are based on HAAT. The Commission also sought comment on whether modified rules should apply across the entire U.S. or only in certain areas, such as less congested areas.
25. The Commission eliminates the requirement that a fixed devices antenna height above ground may not exceed 30 meters generally or 100
meters in less congested areas.
Several parties support eliminating this
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requirement opining that it is unnecessary. As the Commission noted in the NPRM, the separation distances from protected services are based on the antenna HAAT, and the HAAT already takes into account the antenna height above ground. Therefore, there does not appear to be a need for a separate antenna height above ground limit, and limiting the height above ground can unnecessarily limit the maximum achievable HAAT. CP Communications and Sennheiser assert that the Commission has previously concluded that there is no general need to mount an antenna higher than the current limit to avoid shadowing by trees or other obstructions and that the current limit should therefore not be changed. The Commission acknowledges that it did decide in the 2015 White Spaces Order 80 FR 73044, Nov. 23, 2015 that there was no need for a higher antenna height above ground limit. However, upon further consideration the Commission reversed its decision and decided that there was a need to increase this limit in less congested areas in the 2019
White Spaces Order on Reconsideration.
In that proceeding, the Commission stated that real world experience has sufficiently demonstrated that increasing the allowable height above ground would be beneficial for operators in less congested areas and that such a change would not increase the potential to cause harmful interference to other users. In that same White Spaces Order on Reconsideration, the Commission noted Sennheisers concern about potential interference to wireless microphones from a higher height limit, but concluded that limiting higher antenna height to less congested areas, where there are many vacant channels, ensures there will be sufficient spectrum resources in these areas for multiple spectrum users.
Finally, the Commission notes that no party provided specific information or analysis in response to the NPRM
showing that there is actually a need to retain an antenna height above ground limit.
26. However, the Commission is not removing the 10-meter height above ground limit that applies to fixed white space devices operating within the protected contours of adjacent channel TV stations since the NPRM did not seek comment on changing that limit and no party indicated a need to do so.
That height limit could be addressed at a future date.
Separation Distances 27. The Commission increases the minimum required separation distances between white space devices operating
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at higher power and HAAT and the following services in the TV bands: 1
Broadcast television services, including low power; 2 receive sites of TV
translators, low power TV stations, Class A TV stations, Multichannel Video Programming Distributors MVPDs, and Broadcast Auxiliary Service BAS facilities; 3 private land mobile radio services and commercial mobile radio services PLMRS/CMRS, and 4 licensed low power auxiliary service LPAS stations, including licensed wireless microphones. The increases the Commission adopts will protect these services from potentially receiving harmful interference as a result of expanded white space device operating parameters.
28. Broadcast television services, including low power. In the NPRM, the Commission proposed to expand the existing tables of minimum separation distances from broadcast television protected contours both co-channel and adjacent channel to include additional entries for fixed white space device operation at up to 500 meters HAAT
and 42 dBm EIRP. No party argued that the proposed separation distances from co-channel and adjacent channel TV
station protected contours are inadequate to prevent interference to TV
reception. However, several parties request that the Commission significantly change the methodology used to protect services in the TV bands.
Dynamic Spectrum Alliance, WISPA, and Public Interest Spectrum Coalition argue that the Commission should determine white space channel availability using a terrain-based model, such as the Longley-Rice Irregular Terrain Model, which they assert will determine channel availability more accurately than the overly conservative current contour-based model. NAB and Sennheiser, however, oppose using the Longley-Rice model due to concerns about its accuracy in protecting TV
receivers and because it may slow operation of the white space database.
29. The Commission adopts the updated tables of separation distances from TV contours proposed in the NPRM. As noted, NAB supported these proposed separation distances in its comments to Microsofts petition. In addition, the Commission adds a row at the end of each table co-channel and adjacent channel to include separation distances for white space devices with HAAT values over 500 meters and up to 550 meters, which will be used only for the purpose of determining which TV
broadcast stations must be notified when a white space device operates with an HAAT of more than 450 meters and up to 500 meters.

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