Obviously we are still speculating here because the rules are certainly
not
clear. With technology development and the results I am hearing from those
who are using WiMax equipment, I would say that -90 should be a safe signal
level to use and still have good modulation rates. To assume TVWS will
always get full modulation and then try to also claim that it is the most
cost affective way to reach the low population density areas will be
difficult. Site footprints have to be looked at lowest modulation rates
because that RF signal is still out there. It is important to look at how
far that signal will still be traveling even though you can't achieve full
rates. The transmitted carrier will still be out there as part of the
contour for your base and must be considered in the process of
"registration". Your footprint will still be very large even though you
don't prefer to operate at the slower rates, which for others would be
"noise".
To design a network with site footprints and spacing to achieve only
full
rates is an inefficient of spectrum because your undesired signal is still
traveling a great distance preventing others from reusing that same
spectrum.
Thank You,
Brian Webster
-----Original Message-----
From: Mike Hammett [mailto:[EMAIL PROTECTED]
Sent: Wednesday, November 05, 2008 8:29 AM
To: [EMAIL PROTECTED]; WISPA General List
Subject: Re: [WISPA] Theoretical TVWS coverage
I chose -80 because in current operations, anything less isn't really
utilizing the available spectrum. I try to engineer all of my links for
full modulation. Anything less is a waste. I know -80 isn't full
modulation, but it's not far away. Perhaps with more clean spectrum,
receivers will be better, but the same was said about 3650 and that hasn't
materialized.
When browsing around on Channel Master's site that one of their DACs
required -83 to -5 dBm with a SNR of 15 dB to operate. If TVWS devices are
supposed to receive 30 dB below TV, then we should be able to receive
signals that are -113 dBm.
----------
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
--------------------------------------------------
From: "Brian Webster" <[EMAIL PROTECTED]>
Sent: Wednesday, November 05, 2008 7:20 AM
To: "WISPA General List" <[email protected]>
Subject: Re: [WISPA] Theoretical TVWS coverage
> I would imagine you will be able to have receive signals down to
> almost -95
> or -98 dBm. Remember this should be relatively clean spectrum (and
> hopefully
> stay that way). According to Sascha the current white space devices that
> were in testing were supposed to receive signals 30 db below the signal
> required to receive a DTV signal.
>
>
>
> Thank You,
> Brian Webster
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Mike Hammett
> Sent: Wednesday, November 05, 2008 8:12 AM
> To: WISPA List
> Subject: [WISPA] Theoretical TVWS coverage
>
>
> Based on TV antenna, it looks like the largest gain CPE will be around 10
> dB
> for all but the lowest of frequencies.
>
> I just ran a Radio Mobile coverage area using a guesstimate at a white
> spaces system... EIRP of 20 dBm, 16 dBi sector, 10 dBi CPE, -80 dBm
> minimum
> allowed receive. The range wasn't much more than 2 miles in flat country
> land.
>
> With those same measurements with a 36 dBm EIRP, we have 10 miles, but
> terrain comes more into play here.
>
> For the extreme rural areas, this is where tower height comes into play.
> For everyone else, this is your foliage beater. In these areas we still
> need small cells for bandwidth capacity and interference rejection.
>
> Remember, the only signal levels mentioned were 40 mw for personal
> portable
> devices. Anything else is just speculation at this point. They may very
> well give fixed stations 4 W as they do in all other unlicensed bands.
>
>
> ----------
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
>
>
>
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