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[Ham-80211] Access control suggestions

Kris Kirby kris at catonic.net
Mon Nov 22 11:49:56 UTC 2004


On Thu, 4 Nov 2004, Drew Baxter wrote:
> I don't think they're going to kick all the Part 15ers off the current 
> block that is used for 802.11b/g.. So I think we're safer finding ways 
> to adhere access control within the existing footprint at the moment.  
> It's largely easier to co-habitate with the masses than put ourselves in 
> a position where we can lose the allocation where our hill-top gear is.

I have met some hams who had a belief that the Part 15 users were scum and 
unnecessary interference on the band. He had a 180W ATV transmitter on 
2.4GHz (2.3GHz?) and gave a rat's patootie less what anyone short of 
Foxtrot Charlie Charlie thought. I have met others who are attempting to 
get active on 900MHz, despite interference from cordless phones and other 
networks.

The largest hurdle, so far, is the automatic power requirement for Part 
97. Most chipsets don't support dynamicly reducing power according to RSSI 
nor are high power amplifiers availible cheaply for 2.3GHz. Really, Spread 
Spectrum wasn't designed to be run at high power anyway. 

The other thought would be to use wideband FSK and just crap all over the 
band(s), but this could lead to non-intentional interference to other 
users (i.e.: gov't and other hams). 

I'm kinda split on the idea of Part 15 vs Part 97. On the one hand, I've 
worked for a WISP before. On the other, I've been a ham for longer. We 
haven't really lost any space, but both 902MHz and 2.4GHz are shared with 
Part 15 users whether we want to or not. Most hams didn't have access to 
commercial equipment to get on those bands until recently. The other 
problem is that like it or not, Spread Spectrum does have the ability to 
share spectrum with conventional narrow-bandwidth FM carriers. The same 
rules apply, minimum power necessary, but it's unlikely that anything 
short of wall-to-wall FM carriers (a la Nextel) could wipe out Part 15 use 
of a shared band. And even then it's possible that someone could get the 
FCC in on it and they might just smack the ham around because of the 
restrictions placed in Part 97. 

The other issue is that the overall directionality of the antennas at 
2.4GHz just about means you have no excuse for not running the minimum 
power necessary -- a 23dBi dish is quite a bit of gain, compared to a 
dipole or a collinear gain antenna. And then there's the consideration 
toward building your own infrastructure, be it a repeater or a wireless 
network.

Still further, there's the idea of picking your battles and activating 
222MHz, 1.2GHz and 3GHz and so on without going straight into a fight on 
2.4GHz.

I would say losses can be expected at some point, and I wouldn't be 
shocked to see them at either 1.2GHz or 2.4GHz. I would be interested to 
see the impact on Amateur satellite operation, however, as it's rather 
difficult to retune a satellite in orbit around the earth. They could shut 
off the transmitter, but I can't think of much else.

--
Kris Kirby, KE4AHR  <kris at nospam.catonic.net>  TGIFreeBSD IM: 'KrisBSD' 
"BIG BROTHER IS WATCHING YOU!" - 1984-2004 - 20 yrs of Govt Surveillance
 This message brought to you by the US Department of Homeland Security




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