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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 From: David Bagby
[mailto:david.bagby@xxxxxxxx]
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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