[opendtv] Re: F.C.C. Likely to Open Airwaves to Wireless
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 16 Sep 2010 18:30:19 -0500
Craig Birkmaier wrote:
>> Not to forget that each WiFi channel is 20 MHz wide - the equivalent of
>> more than three adjacent TV channels. So honestly, I don't know why the
>> FCC hypes this white spaces idea so much. Long range, perhaps, but
>> you're only going to get very few WiFi networks in those "white spaces,"
>> and each will only offer so much b/s of shared capacity. You can't
>> assume MIMO will work so well, when widely distributed users will be
>> sharing the channel.
>
> What is to say the white spaces devices will need to use 20 MHz channels?
But the capacity will suffer if they use less than WiFi. In other words, you
can't go in assuming that just because 802.11n can get as much as 100 Mb/s of
capacity, white space devices will give you that 100 Mb/s over a huge area. And
even if they did, it would only be shared by that many more people.
Using the lower frequency bands is a liability as much as an asset, and it's
not very likely that the MIMO techniques that work with small hot spots can be
applied nearly as effectively at longer range. So my take is, hyping up this
white space use as "WiFi on steroids," as the FCC did, is just the sort of
hyperbole that is meant to distract the innocent. (Worse, some of the FCC guys
might actually believe the nonsense.)
> Seems to me that there is going to be a lot of experimentation to see what
> works best. Rice Unversity just got a large grant to enhance its campus
> networks using white space spectrum.
I saw that elsewhere. Of course, they are happy. Grant money is wonderful. As
long as they take away the auto-detection "feature," I am happy. That will mean
that the consumer devices won't even have the opportunity to screw things up,
as long as the FCC database is designed correctly. And if intereference does
occur, there is some hope for recourse.
Bert
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