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Steve,
I
honestly do not think that .19 should go down that
road.
If it
does, I strongly suggest that requirements to scan for other 802 family
wireless devices would have to apply to ALL 802 wireless devices.
Let's
consider:
1) The
ISM bands are what they are: ISM band devices are required by law
to accept any interference received from other ISM
devices.
2)
Another factoid is that 802 devices constitute a small portion of the things
found in ISM bands. (ref the tutorial given by the hospital guys re what they
saw in ISM bands when they scanned).
3) Independent of if we like it or not, the mixture of signals in
the ISM bands is not static - what one accounted for in yesterday's design may
or may not be good enough tomorrow - the band signal content is
dynamic.
4) The law has no analogy of a homestead act for
spectrum in the ISM bands - Ownership of spectrum is not conveyed by sales of
devices.
5) The source of what one's device perceives
as "interference" is not really relevant (in that it does
not matter if it is from another 802 device or a non-802
device). 6)
Channel width used by a device is also not relevant (100 1MHZ adjacent channels
fill the same amount of spectrum as 1 100MHz channel).
My
pragmatic conclusion, developed over many years, is that if
one wants to play in the ISM bands, one had better be able to operate in
the ISM environment, including accepting the interference one is likely to
receive. If one's device can't handle that, don't expect to have a
successful product.
SO then I ask why scan for 802 devices?
Presumably because "someone" wants "something" to happen to make
their operation "better" when the "other" devices are found....
Who is
to say what use of the ISM band is more important that another?
The
only consistent answer to those questions I would expect to hear is "mine is
more important than yours"; a rat hole argument that can never be
"won".
I've
observed that people tend to react emotionally along the lines of
"just don't interfere with me"....
ISM band
reality is that if ISM product operation depends on assumptions
that can not be guaranteed in the ISM band, one may not have made a good choice
of spectrum for the product design.
When I
consider these points, I wonder what is the benefit of having 802 devices
looking for only other 802 devices?
What
will they do when they find them?
Who
gets out of the way of whom?
why?
based
on what objective or criteria?
Having
found 802 devices, does it matter given the full extent of devices operating in
the ISM band?
Seems
to me like a lot of work to address a rather small percentage of the ISM
"interference sources".
Suppose 802 did
eventually require that all 802 devices look for other 802 devices....
to what end?
how would 802 keep that updated as new devices are
invented?
Cross coupling operational aspects of different 802
standards in that manner would seem to be an enormous complication; and one
that I don't see a payback for. The pace of the 802 standards process
pretty much tells me that by the time that "802 family scanning" were
standardized, the assumed mixture of devices would be obsolete. And what would
old 802 devices do wrt to new ones? they would have no way to know how to scan
for them...
I think it very unwise for .19 to attempt to extend
simple "coexistence" (which is not and has never been a synonym for "zero
interference interaction") into "cross 802 wireless standard awareness" or (even
more complicated) "dynamic spectrum management between 802 devices".
I suspect that anyone which sticks a toe in that
tar pit is unlikely to ever see their toe (or foot or...)
again...
Dave
____________ David Bagby
Calypso Ventures,
Inc. office: (650) 637-7741 email: Dave@xxxxxxxxxxxxxxxxxxx
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