[opendtv] Re: Will Femtocells Save LTE?
- From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 30 Apr 2011 17:51:54 -0400
Craig Birkmaier wrote:
> I agree that the tower density does not need to be the
> same as for the two-way LTE infrastructure, although this
> may be a moot point, as once you site a tower, adding
> services in another frequency band is trivial.
Not trivial for the network that has to pay to keep all the towers going. I do
agree that ultimately, if RF bandwidth were so plentiful that TV broadcast
became a small fraction of what was required, and their contibution to the
upkeep an equally small fraction of the total, then sure. Piggy-back.
The bottom line is, leaving aside archaic artificialities such as FCC national
caps on broadcasters (and time zone considerations), the most spectrally
efficient way to broadcast nationwide networks is NO FREQUENCY REUSE. NBC gets
the same frequency channel nationwide, with the smallest possible use and
expense of a cabled infrastructure, and no one else touches that channel.
Conversely, the most spectrally efficient to provide two-way wireless service
is, ultimately, to use the same frequency channel, re-dedicated individually to
every two-way appliance. And the wide coverage is created by leveraging off a
fiber optic, routed backhaul network. Those are the limiting conditions.
> The other way around Bert.
> Big sticks are very expensive:
> Expensive site;
> Expensive to build;
> Expensive to operate.
Everything is comparative, Craig. You won't convinced anyone with mere words.
As expensive as big sticks might be, the fleet of trucks and individuals
required to keep telco networks going is considerably higher, which is why they
can't afford to provide these with only ad revenues. But do feel free to give
the actual numbers involved here, for the two types of networks.
> In other words, when you create more distributed transmission
> network, ...
I know about ease of reception, Craig. I just finished saying that the only
reason you might want more towers, in a nationwide broadcast network, is for
ease of reception considerations. Whereas in a two-way unicast network, you
need as many towers as possible, limited only by the hand-over protocol
overhead, for scaling considerations. Two different environments, two different
solution sets. You can't assume that the words that express the goals of a
two-way unicast network must also apply equally to one-way broadcast.
Since you bring up the hyperlocal concept, those stations are more similar to
the unicast model. They may not even belong on longer-range RF channels at all.
For much the same reasons that unicast sessions don't. Or, LPTV, which works
perfectly well with ATSC, and in fact does allow frequency reuse between
adjacent markets. As I already pointed out to you, using real FCC tables.
(Note: a low PAPR helps in reducing co-channel interence, which is one
attribute that hyper-local RF broadcasting would need.)
Bert
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