[opendtv] Re: News: TV Braces for the Apple Tablet

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Mon, 1 Feb 2010 15:50:51 -0600

Craig Birkmaier wrote:

> I am talking about wireless broadband - cellular is so passe'

Wireless broadband and cellular are not mutually exclusive. Matter of fact, 4G 
cellular could very well be a viable technique for wireless broadband. 
Broadband implies two-way links, optimized for unicast transmissions (i.e. 
point-to-point links for individual sessions).

> We're talking about a tiny fraction of the bits that are being
> broadcast, and it is not clear that once the link is
> established there would need to be any further communication
> unless the device moved to a new cell.

The original article mentioned interest in broadcast TV among cell phone users, 
so I am taking that as a given. And yes, it is inefficient to tie up individual 
two-way cell links with this broadcast traffic. Again, those two-way links are 
prime real estate, which should be dedicated to two-way unicasts, not wasted on 
wideband TV signals that can be sent on one-way channels, bypassing the cell 
structure completely.

> The MAJOR difference is that MHP from big sticks requires
> protection in adjacent markets - i.e. white spaces. This is
> horribly inefficient compared to the spectral reuse of cellular
> networks.

Think about it Craig. A cell network is exactly the same thing as a big stick 
model, scaled down. Which means, you STILL have to protect those frequencies. 
It's just that this protection is done on a smaller scale, and infinitely more 
often, that's all. So, instead of worrying about this protection issue only 
from one city to the next, you worry about it neighborhood by neighborhood, 
using lots and lots of towers, where one tower is all you need if the signal is 
one-way broadcast that many can use simultaneously.

The frequencies used in the Wash/Balt markets are not used by Philadelphia, but 
are reused in NYC. Similartly, in cell networks, the frequencies used in one 
cell cannot be reused in any adjacent cells. You have to get to the next ones 
beyond before reusing. It's the same problem, solved the same way.

Bert
 
 
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