Hi Bernard-
In the spirit of my recent harangues (WCII's broadband data not getting either respect OR DCF valuation), thought it'd be interesting to discuss differences in spectral efficiency (ie., TGNT vs WCII / 24GHz vs 38GHz).
So WCII uses 100MHz as a "channel". I know we interacted before and you mentioned a 1:1 rule of thumb, but WCII claims to offer OC3 per channel, representing an approximate 50% capacity gain (1.55:1) over your guideline.
And when TGNT had it's 18GHz taken and replaced with 24GHz, as I remember, the FCC gave them 4 times their original bandwidth to compensate for the lower channel capacity of the higher freq. There apparently was a congressional investigation about that (that they were WAY overcompensated), which I presume is still ongoing.
So, assuming identical (or equivalent) modulation schemes (and is such an assumption reasonable for different freqs? ie., is 'efficiency' - frequency dependant in any appreciable way over the bands we are considering?) is there a theoretical (under standard conditions) fixed relationship between increases in freq and decreases in modulation spectral efficiency (channel capacity)? And how do frequency reuse factors fit in, for data as well as voice channels, assuming appropriate C/I (>18dB?) for each?
If from 18GHz to 24GHz "theoretically" requires 4x the bandwidth (BTW, does it?), what kind of capacity loss occurs going from 24 to 38?
And is there a definitive wireless handbook that addresses these kind of technical issues thoroughly, that you might recommend?
Lastly, with P-MP, what's the theoretical sectorization (I've heard 3 deg) and what's considered real-world interference safe (I've heard WCII is using or planning to use 15 deg)?
Any thoughts or pointers appreciated.
BTW, I'll be at NBMO Telecom conference in NY next week, so any burning (and *answerable*) questions are welcome. ...I wonder if Bill R will bring David Ackerman in from DC...
Thanks-
Steve |
