On October 28, 2020, the FCC released the Report and Order and Further Notice of Proposed Rulemaking (“R&O” and “FNPRM”) in the Unlicensed White Space Device Operations in the Television Bands matter (ET Docket No. 20-36).  This item was adopted at the October Open Meeting.  Note that the adopted item contains a FNPRM seeking comment on whether to permit use of terrain-based models such as Longley-Rice Irregular Terrain Model to determine available TV channels for white space devices, which was not included in the draft version of the item.


R&O:  The adopted R&O incorporates the following relevant changes from the circulated draft version:

  • ¶ 37 –The draft item declines to alter the current method of protecting TV stations by changing to a terrain-based model.  The adopted R&O softens this language to decline “at this time,” recognizing arguments that more sophisticated propagation models could possibly identify unused TV spectrum more accurately than the current contour-based model while still protecting TV service from harmful interference.  The FCC accordingly adopts the FNPRM to seek comment on the use of terrain-based propagation models.
  • ¶ 58 – The FCC agrees with arguments made by Shure that the proposed distance for the geo-fence area buffer for a white space device operating within a geo-fenced area should be increased to account for vehicles traveling on highways and accordingly adopts a geo-fenced area buffer of 1.9 kilometers.
  • ¶ 64 – The FCC expands the definition of “narrowband white space device” to include master devices as well as clients.  Accordingly, narrowband devices that act as a master must incorporate a geo-location mechanism and be capable of obtaining lists of available channels and operating powers from the white space database.  All types of white space devices that incorporate geo-location and have database access are permitted to act as a master device to a narrowband client device.
  • ¶ 66 – The FCC declines to increase the transmission time limit for narrowband devices to allow for signaling overhead as suggested by Microsoft.  Microsoft did not indicate how much additional transition time was necessary for this overhead, and the FCC concluded that there appeared to be ways to perform these functions while still complying with the 36 second per hour narrowband channel limit.


FNPRM:  As noted above, the FNPRM requests comment on the use of a terrain-based propagation model such as Longley-Rice for determining white space channel availability.  The Longley-Rice propagation model is used to make predictions of radio signal field strength using the median attenuation calculated as a function of distance and the signal variability in time and space.  This model can be run in point-to-point mode or in area mode and uses a terrain elevation profile to make predictions.  It requires a large number of reception points to be individually examined and a large set of input, system, environmental, deployment, and statistical parameters.  The FCC seeks comment on what effect using a model such as this would have on the availability of channels for white space devices, how this type of model could be implemented within the current white space device framework, the technical parameters necessary to use such a model for identifying available spectrum while protecting incumbents from harmful interference, and various database and device implementation issues.  Comments will be due 30 days after Federal Register publication with Reply Comments due 60 days after such publication.


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