[IP] Re: Your comments appreciated: Beyond White Spaces

[David Farber <dave@farber.net>]

Begin forwarded message:

From: Brett Glass <brett@lariat.net>
Date: October 26, 2008 4:56:39 PM EDT
To: dave@farber.net, "ip" <ip@v2.listbox.com>
Subject: Re: [IP] Your comments appreciated: Beyond White Spaces

Dave, and everyone:

Making the TV white spaces into Part 15-style unlicensed bands is a  
HORRIBLE idea. Why? Well, firstly, the spectrum isn't needed for that  
purpose. With 500 MHz of unlicensed spectrum at 5 GHz, plus 50 MHz at  
2.4 GHz, PLUS the 20 MHz of spectrum at 900 MHz, do we really need  
more spectrum for cordless phones and baby monitors? No. What we need  
the spectrum for is to deliver wireless broadband, on frequencies  
which are NOT polluted by an untold number of consumer devices.

Secondly, the laws of physics come into play here, in a big way.  
Signals transmitted on the former TV frequencies can penetrate walls  
and go for miles, interfering with all the other devices in town  
operating in the same band. Is this what we want for consumer devices?  
Of course not! If anything, we should allocate higher unlicensed  
frequencies -- which have a HARDER time penetrating walls -- so that  
each user's home is his or her "spectrum castle." If any more spectrum  
is needed for indoor wireless (though it's not clear that it is), how  
about liberalizing the rules for the 24 GHz unlicensed "low millimeter  
wave" band so that it can be used in the home? This would make far  
more sense than turning consumer devices loose on the TV bands. The  
"white spaces," in turn, could be reserved for services that deliver  
wireless broadband right through the walls of these "castles," so as  
to connect them to the Internet without drilling holes or mounting  
outdoor antennas.

Thirdly, since the radios used on these frequencies have to be  
"cognitive" anyway (they have to make sure not to step on TV  
channels), they might as well use their intelligence to make better  
use of the airwaves. As I explain in my talk at

http://www.brettglass.com/CR/

Shannon's Law dictates that the way to get the greatest utility out of  
spectrum is not to slice it up into little chunks and license it  
exclusively, but rather to share large swaths of spectrum,  
intelligently, using cognitive radio technology. In fact, if we do not  
do the latter, wireless will never be useful to deliver "ultra- 
broadband" -- that is, speeds of 100 Mbps and up -- to multiple users  
from a single transmitter. The laws of physics and information theory  
indisputably dictate this; again, see the slides at the link above.

Fourthly, using this spectrum to deliver service TO the home rather  
than for unlicensed devices WITHIN the home would help ensure that  
this use would not interfere with television broadcasters, because  
providers' antennas -- which would be located outdoors on towers and  
buildings and would be very sensitive -- would be much better situated  
to detect any broadcast signals with which they might interfere.

So, what we really need is NONEXCLUSIVE licensing of the TV white  
spaces -- similar to the licensing which has been established for the  
3.65 GHz band, but with a mandatory spectrum etiquette that allows the  
spectrum to be shared among multiple broadband providers and their  
customers. This would maximize the use of the spectrum and also  
consumer choice. It would this be far better than Tom Hazlett's  
concept of total exclusive licensing (which would just allow the big  
cell phone providers to warehouse yet more spectrum) or the New  
America plan (which would turn the spectrum into a useless "junk  
band." A simple understanding of physics, radio technology, and  
consumer needs leads inevitably to this as the best possible use of  
the TV "white spaces."

--Brett Glass





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