[opendtv] FCC Forum Examines Broadcast Spectrum Reclamation
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 10 Jun 2010 18:25:10 -0500
"One topic is 'Cellularization of Broadcast Architecture,' which is has been
proposed as a way to allow channels to be reused without the normal spacing
normally required to avoid interference between high-power single site
transmitters. While this technology has some promise, it wouldn't solve the
problem of the insufficient number of channels available in larger markets, and
would require a huge build-out of towers, microwave or fiber links, and
transmitters, along with extremely complex engineering to avoid interference to
existing receivers, particularly in markets with terrain issues such as Los
Angeles and New York."
Looks to me like at least Doug Lung understands the problem.
I would not even honor this idea with "has some promise," for its intended goal
of reducing the need for spectrum, UNLESS it is accompanied by changes in how
TV markets are structured. Meaning, allow or even promote regional
broadcasting. Why not discuss the complete picture, so as to educate rather
than obfuscate the attendees? SFNs can save spectrum, but HERE ARE THE COSTS.
What's wrong with the complete truth, once in awhile?
As to the term "cellularization." Maybe they should have some telco cellular
engineers present, to explain to the FCC what cellular really entails. For
example, the idea that cell architectures are designed to overlap quite
deliberately, and that "cellular" consists of adjacent transmitters on
different frequencies. It's annoying to see the innocent misuse terms, and then
misinterpret the expected outcomes based on their misconceptions.
Bert
-----------------------------------
http://www.tvtechnology.com/article/101870
FCC Forum Examines Broadcast Spectrum Reclamation
by Doug Lung, 06.10.2010.
During the NAB Show, FCC Chairman Genachowski announced that the FCC would
convene an "Engineers Forum" to address technical issues raised by the National
Broadband Plan (NBP) and "develop the next path forward." Until yesterday, I
hadn't seen any public announcements concerning the Forum or the topics to be
covered.
On Wednesday the FCC announced [PDF] details about the forum and the topics to
be discussed. The list will be familiar to anyone who has seen the
recommendations in the NBP, and they are clearly focused on ways in which the
FCC can achieve its goal of taking what amounts to almost half of the usable TV
broadcast spectrum remaining after the DTV transition a year ago. (This
excludes land-mobile, channel 37 and channels 2 through 6.)
One topic is "Cellularization of Broadcast Architecture," which is has been
proposed as a way to allow channels to be reused without the normal spacing
normally required to avoid interference between high-power single site
transmitters. While this technology has some promise, it wouldn't solve the
problem of the insufficient number of channels available in larger markets, and
would require a huge build-out of towers, microwave or fiber links, and
transmitters, along with extremely complex engineering to avoid interference to
existing receivers, particularly in markets with terrain issues such as Los
Angeles and New York.
Another group will look at "Methodologies for Repacking the TV Band."
As difficult as it was to move TV stations from channels 52-69 to new slots
last June, most stations operating at cutover time then had been authorized two
channels. In many cases if they couldn't stay on their pre-transition DTV
channel, they could use an existing analog antenna and perhaps convert an
existing analog transmitter for DTV broadcasting on their old analog channel.
However, if stations were forced to transition again, things would be more
difficult for many of them, and it would be a lot more difficult for stations
in the most populated parts of the county.
Stations moving from UHF to VHF would need new antennas, new transmitters, and
maybe new towers, although in some markets if celluarization can be made to
work, a single large antenna, transmitter and tower could be replaced with 20
or more (perhaps many more, depending on the area and power) small to medium
power transmitters, antennas and towers.
All of the channels that would be reallocated to wireless carriers are UHF,
which means VHF channels, including low-band VHF, may be the only option for
broadcasters not willing to give up their own off-air broadcasting. It isn't
surprising then that one forum group is devoted to "Improvements in VHF
Reception." However, the disadvantages of VHF channels, even high-band channels
for DTV, became clear after the analog shutdown. As I've been reporting,
advances in metamaterial antennas could improve receive antenna efficiency and
reduce some of the VHF disadvantage on high-band channels, but it won't help if
noise from switching power supplies, TV sets, motors and power lines overwhelms
the DTV signal. Increasing transmitter power could raise other interference
issues due to the enhanced propagation that can take place at lower VHF
frequencies.
Another way to minimize the impact of taking away such a large block of
broadcast TV spectrum is to use the remaining spectrum more efficiently.
Stations that are not interested in multicast, mobile DTV or high quality, fast
action HDTV might be willing to cash in their channel assignment and share a
19.39 Mbps channel with another TV station. Moving U.S. broadcasting from
MPEG-2 to MPEG-4 (AVC) compression technology would free up data bandwidth, but
would obsolete every existing DTV set and DTV converter box.
And what if stations want to hold onto that "found" data bandwidth for their
mobile DTV operations?
Stations currently broadcasting an HD channel and one or two SD channels may be
interested in partnering with a station that isn't using as much data bandwidth
in order to add more mobile DTV channels and services. The question remains:
Would Mobile DTV be able to compete with Verizon, AT&T and the other wireless
carriers for this spectrum?
The engineers participating in these groups won't have an easy time finding a
way to eliminate almost half the currently usable TV broadcast spectrum.
The FCC is not allowing public access to the working groups, but on Friday,
June 25, the reports from the groups will be available online. The reports are
limited to 30 minutes per group. Before the reports, there will be a short
welcome and overview at 3 p.m. EDT.
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