> I would say that -90 should be a safe signal > level to use and still have good modulation rates.
I'm a little confused on that statement. With our Aperto live testing a few years back (pre-wimax), the best modulation we could get was qam16 at the -85 levels. And that was before considering the 25db SNR required above the noise. What good is sensitivity, if the noise ends up being higher than the sensitivity? Sure TV broadcasters shot for -120, but thats one direction broadcasting, with no expense cut for technology. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Brian Webster" <[EMAIL PROTECTED]> To: "Mike Hammett" <[EMAIL PROTECTED]>; "WISPA General List" <[email protected]> Sent: Wednesday, November 05, 2008 8:46 AM Subject: Re: [WISPA] Theoretical TVWS coverage > > 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 >> >> >> >> -------------------------------------------------------------------------- > -- >> ---- >> WISPA Wants You! 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