Dave,
Thanks for your comments.
I would just like to point out that 802.19 is just a TAG and as such is a forum
for having technical discussions. The decision on the 802.11n draft is in
the hands of the WG and the WG/Sponsor ballot voters, the EC, RevCom and the
SB, not the 802.19 TAG.
The TAG is not setting policy it's a forum for technical debate.
There was a request for such a discussion. Are you suggesting that I tell
those who requested such a discussion that the TAG will not allow for such a
technical discussion? I think not.
Regards,
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.
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?
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....
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...
-----Original Message-----
From: Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxx]
Sent: Wednesday, October 22, 2008
3:05 PM
To: STDS-802-19@xxxxxxxxxxxxxxxxx
Subject: [802.19] Possible 802.11n
spectrum scanning requirements
All,
On the 40MHz 11n coexistence conference call it was suggested that the 802.19
TAG start to look at possible Spectrum Scanning Requirements. A
proposal was made to add include an option for spectrum scanning in the
standard. The proposal was made by John Barr and can be found at,
https://mentor.ieee.org/802.11/file/08/11-08-1101-04-000n-additional-40-mhz-scanning-proposal.ppt
While the 802.11 WG discusses the merits of this proposal, the 802.19 TAG is a
good forum for having technical discussions on possible requirements and
technical feasibility. This information may be useful to 802.11 in making
its decision on how to address this proposal. The text on Slide 6 of
John's presentation beings to discuss possible requirements. That may be
a good place to look at to stimulate thinking on this topic.
During the conference call it was suggested that the primary non-802.11 systems
that are of concern are 802.15.1 (Bluetooth) and 802.15.4 (Zigbee) since they
both operate in the 2.4 GHz band.
Anyone who would like to prepare a presentation on possible spectrum scanning
requirements for these non-802.11 systems please notify me. We can
discuss any such presentations on the next conference call on November 3 or at
the Plenary meeting in Dallas.
Thanks,
Steve