[opendtv] Re: Small cells still not ready for mobile prime time
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 25 Jun 2012 18:54:39 -0500
Craig Birkmaier wrote:
> I'm not sure why broadcasters would need to deploy small cells. Perhaps in
> very localized areas like a football stadium. But congestion is not an
> issue on a Broadcast LTE network as the goal is to deliver multicasts.
>
> The issue that may be relevant is cell synchronization of these multicasts
> to deal with receivers that may "see" multiple towers...
Yes, all of this stuff is inter-related. The short answer is, if you want to
achieve high b/s/Hz, you are going to be restricting the size of each cell. I
suppose you could go for the big stick model, and then you'd be less
restricted. But that kind of defeats the purpose of LTE.
Go to:
http://world2011.itu.int/sites/default/files/pdf/TS07%20-%20Huschke_Presentation.pdf
Viewgraph #9. It shows how spectral efficiency degrades as the tower spacing
increases. And the drop is rather precipitous, by OTA broadcast standards.
In my numbers previously, I assumed NO INDOOR service to speak of, and spectral
efficiency down to 1.4 b/s/Hz. Compared with the big stick model, I'd say
that's giving LTE a break. But to achieve even that, you're still going to need
2.5 mile spacing. That's fairly small, yes?
That's why broadcasters would want to deploy small-ish cells. And if they
wanted to allow reliable indoor service, it's a lot worse.
Bert
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