Mark Twain once said, “Buy land.
They’re not making it anymore.”
Such is the case with electromagnetic
frequency spectrum. They’re
scarce, coveted, and very expensive.
Furthermore, they’re subject
to regulation both nationally and
internationally.
The general consensus is that
most of the good spectrum are
already allocated. But the opposing
view is that lots of existing unused
or underutilized spectrum could be
used (see “A Technology Solution
To Spectrum Limitations”).
Both views are correct up to a point.
The recent transition from analog
to digital TV has freed up some
great spectrum in the U.S., and the
Federal Communications Commission
(FCC) is attempting is to make
more efficient use of it.
The frequency spectrum is a continuously changing landscape.
The best way to keep up with changes is to monitor the two U.S.
agencies that control it: the FCC and the National Telecommunications
and Information Administration (NTIA).
The FCC deals with personal and commercial spectrum, while
the NTIA handles government and military spectrum assignments.
Their Web sites offer a mass of information for those who
need to follow regulatory actions. And while the U.S. spectrum
is relatively settled, two recent events have opened an unusually
large segment previously tied up by TV broadcasters.
First, the broadcasters abandoned their assignments from channels
52 to 69 (698 to 806 MHz) as part of the FCC-mandated
digital TV switchover. This is the so-called 700-MHz spectrum.
It was auctioned off last year in Auction 73. A total of 101 bidders
won 1090 licenses for a net income to the U.S. Treasury of
$19,592,420,000.
AT&T and Verizon won most of this spectrum for cellular
expansion, but other licenses will support mobile TV, wireless
broadband, and a mix of other services. Little or none of the spectrum
is in use so far, but it will be soon because of the final digital
TV switchover on June 12.
Second, in another action related to the DTV transition, most
TV stations were assigned new operating frequencies in the
remaining spectrum from channels 2 through 51 (54 to 698 MHz).
These new assignments don’t use all of the available spectrum.
Many gaps exist, and they vary in frequency depending on the
local TV station’s frequency assignments. These gaps of unused
spectrum are called “white spaces.”
The FCC recently declared that these
unused frequencies may be applied to
new wireless services. These new services
will be unlicensed, and they will
come under the FCC’s CFR 47 Part 15
as recently amended. This spectrum still
retains its 6-MHz channel assignments,
though, and the available bands vary from
locale to locale.
The spectrum assignments in the U.S.
are a nightmarish tangle of regulations
and recordkeeping. Changes occur daily,
so keeping track of it all is difficult. While
who owns and uses which spectrum is
generally known, some forgotten assignments
and recent changes slip through
the cracks. This lack of exact knowledge
of the spectrum assignments recently led
to the Radio Spectrum Inventory Act,
a bill sponsored by U.S. Senators John
Kerry (D) of Massachusetts and Olympia
Snowe (R) of Maine.
The bill directs the FCC and the NTIA
to perform a U.S. spectrum audit and report on the use of all
spectrum from 300 MHz to 3.5 GHz. The outcome of this bill
should more clearly define spectrum usage. It will determine if
the spectrum is overcrowded as well as if unused segments could
be put to good use (see “What’s So Special About The White
Space And 700-MHz Bands?”).
Also, it should help ensure that our available spectrum is fully
used for the benefit of U.S citizens, increasing services for consumers
and profit for businesses, especially in the broadband
service sector. Never before has so much good spectrum opened
up at the same time. It no doubt presents many new products and
services possibilities.
WHAT TO DO WITH 108 MHz OF BANDWIDTH?
That’s the total amount of available spectrum in the 700-MHz
block. Spectrum blocks don’t always follow the original 6-MHz
channel assignments. The gray C and D blocks in Figure 1 in the
lower 700-MHz band and the gray A and B blocks in the upper
700-MHz band were auctioned off before Auction 73 last year.
The remaining blocks were sold off in Auction 73, except for the
D block in the upper 700-MHz segment.
So, how will these bands be used? Most of the spectrum will
go to cellular service expansion. Cellular service continues to
grow as more new subscribers come aboard, including those
dropping their wired telephone service in favor of wireless only.
Consequently, there’s always a demand for more spectrum among
carriers and operators.
Another factor is the increased use of data services—specifically
messaging, e-mail, and Internet access. And much of that Internet
access involves video. Data services require more bandwidth
to push data speeds to a level that’s satisfactory for subscribers
expecting data rates comparable to their home broadband services.
Most carriers are seeing steady growth in 3G data services.
Also, new 4G cellular technologies like Long-Term Evolution
(LTE) will be implemented in 2010 and beyond. LTE will bring
even faster data services (Fig. 2). Yet this orthogonal frequencydivision
multiple-access (OFDMA) technology, which uses multiple-
input multiple-output (MIMO), needs more bandwidth.
Some of the spectrum has already been allocated to mobile TV.
MediaFLO is transmitting on old TV channel 55 to cell phones
with built-in receivers. Additional spectrum was assigned to
mobile TV. AT&T recently announced the beginning of its Mobile
TV effort in 20 new markets nationwide. It includes CBS, Comedy
Central, and MTV. Both LG and Samsung offer phones with
mobile TV capability for this new service (Fig. 3).
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