SPECIAL REPORT: FCC White Space Rules
WASHINGTON: The FCC’s latest ruling on unlicensed devices
operating in the TV spectrum modifies the original 2008 order in four areas: Incumbent
services, the devices themselves, databases they’ll be required to check and
the use of TV channels. The changes address 17 petitions to reconsider the 2008
order, though the FCC said it upheld “the majority” of those rules.
The commission’s Second Memorandum Opinion and Order, released last Thursday, represents
the final parameters governing TV band devices, or TVBDs. They represent a new
class of personal communications gear that will be allowed to operate in
unoccupied TV channels, aka “white
Broadcasters fought TVBDs because their potential to disrupt TV reception was
unknown. As no such devices are on the market and only prototypes have been
tested, this remains a concern. Particularly now that the commission eliminated
a requirement that TVBDs automatically sense occupied channels. The devices
instead will rely entirely on communicating their geographic coordinates to privately
owned databases of channel usage and availability.
TVBD Types and Power Levels
Three basic types of TVBDs are described in the FCC’s ruling--fixed, and portable
Modes I and II. (“Portable” as in movable but stationary in use, versus
“mobile” as in constant motion. The FCC has not yet taken up mobile TVBDs.) Fixed
devices are just that--tethered to a single location, e.g., a home Wi-Fi modem.
Mode II portable devices are those with integrated capability to communicate
with the databases. Mode I describes portable TVBDs that are dependent on base
stations or Mode II devices.
Portable TVBDs will be allowed to operate at 40 mW in channels adjacent to
TV signals, and 100 mW elsewhere. A petition by the Community Broadcasters
Association to reduce the adjacent-channel power level was rejected. However,
all TVBDs--fixed and portable--must have technology that adapts power levels to
the minimum necessary to accomplish communications.
Portable TVBDs will be allowed to operate on unused channels between 21-51. Fixed
TVBDs will be allowed to operate at 4 W on unoccupied channels between 2-51, except
for 3,4, and 37 (the latter used for radioastronomy). Fixed TVBDs will be
prohibited from operating on channel immediately adjacent to TV signals. They
will also be required to transmit an identification signal.
The commission modified the rules governing the allowable antenna height for
TVBDs. Rather than just 30 meters above ground as previously defined, a height
above average terrain, or “HAAT” was added. Fixed TVBD antennas will be
prohibited from operating above a HAAT of 106 meters.
The 2008 order required all TVBDs be capable of sensing analog and digital TV
signals as well as wireless mics operating at specified power levels. This
requirement was dropped in the final order for devices that access a
geo-location database. The FCC said it nonetheless expects manufacturers to
voluntarily include spectrum-sensing technology in such devices. >
The commission said it would also accept applications to certify sensing-only
devices under a “proof-of-performance standard. Such devices would have to
sense wireless mics and other low-power auxiliary stations at a minimum
threshold of -107 dBm, up from -114 dBm. The minimum threshold for TV signals
remains -114 dBm. The power limit for sensing-only devices is 50 mW.
The elimination of compulsory spectrum sensing means TVBDs can rely solely on
database exchanges to avoid TV signals and wireless mics.
Part II: Geo-location Databases
Become Primary Means of Avoiding Interference”
Part III: EXCLUSIVE: “Nine Vie to Manage White
Part IV: “Wireless Mics Afforded
Two Exclusive Channels”
Part V: “Commissioners React to