On Tue, 12 Jan 2010, Richard Chycoski wrote: > This reminds me of a line from an early Star Trek episode: > > "Ugly sacks of mostly water" to describe human beings. And 2.4 GHz is quite > susceptible to water absorption, especially at 2.45 GHz. > > Also remember that some things *reflect* RF, which can make a mess of those > nice antenna patterns that you thought you were getting out of that > directional antenna. At $WORK we have a regular pattern of access points on > the ceiling of every floor (in typical concrete/steel buildings). It still > took the network crew quite some time to get things adjusted, but the > difference between a typical office and a conference is that *everyone* at > the conference is vying for wireless access, in the office most of the > devices are wired with only a small percentage wireless.
this is why I intend to get in there a few weeks ahead of time to measure the effect. > Rather than trying to customise every antenna pattern, using a regular > pattern of omnidirectional APs with the power down low and the channels > designed like a typical cellular system with no adjacent use of the same > channel (tougher than it sounds!) is likely the best that you can do. given that there are only three useable b/g channels, this isn't possible with omnidirectional antennas. > And about the SSID - yes, make it the same everywhere. You don't want to have > to explain about multiple SSIDs to the users. > > I would also configure all of the APs for 'b' only (no 'g') to get the > maximum use of your channel space. Mixing AP types as you have suggested may > cause you more headaches, but then since $WORK builds our own, it's easy for > us to use all the same AP everywhere - but it sure does make WiFi roaming > between the floors (and buildings) less troublesome. b and g use the same channels, just at different speeds. I would expect that everyone would be using g nowdays, and the more people who use g the shorter the transmissions, and the less cluttered the airwaves > Especially if this is one, big convention room floor (or even a few big > cavernous halls), I'm not that lucky. I have one middling size convention room floor on one floor, and a bunch of smallish rooms spread out on the second floor > expect to be 'the guy' getting cursed at for the lousy > wireless service - it's part of the gig, y'know! ;-) yep, I just hope to do better than I've seen before. David Lang > - Richard > > Chuong Dao wrote: >> I've setup a fairly large wireless system. The event was at a conference >> for about 10K of people. I the test setup went well at my work location. It >> did not perform well at the event. Later, I found out that human bodies >> absorb signals. You might want to read up on that. >> >> -CD >> >> -----Original Message----- >> From: discuss-boun...@lopsa.org [mailto:discuss-boun...@lopsa.org] On >> Behalf Of da...@lang.hm >> Sent: Tuesday, January 12, 2010 2:17 AM >> To: LOPSA Discuss List >> Subject: [lopsa-discuss] high density wireless >> >> When attending confrences in past years I have been frustrated at the >> quality/reliability of the wireless access. In many cases it's been clear >> that the person setting things up did not understand the effects of many >> computers in a small area.. >> >> Well, I now have a chance to show that I can do a better job. >> >> I believe I have a good handle on managing the RF side of things (set the >> access points to low power, use directional antennas to get coverage of the >> rooms without overlapping other access points, I have a wifi spectrum >> analyser to be able to measure coverage and the effect of the walls, etc) >> >> However, I can't think of anything particularly special on the IP side of >> things that I need to do. I can rate limit individual connections, use >> something like packetfence to watch for machines that look like they are >> infected and try and isolate them. >> >> I can police the vendor area with the scanner and ask booths that bring up >> their own access points to disable them (a major problem in past years) >> >> The access points available are a combination of 3com 7760 and WRT54GL >> (changing the firmware on the WRT APs is an option), I may buy a couple >> more, possibly picking up a couple N capible devices (not for the speed, >> but for the extra channels to try and releive the RF congestion) >> >> Should I try and put smarts in the APs? or just let them be a flat net with >> one SSID and do everything at the gateway/DHCP server? >> >> >> >> So what am I not thinking of? >> >> David Lang >> _______________________________________________ >> Discuss mailing list >> Discuss@lopsa.org >> http://lopsa.org/cgi-bin/mailman/listinfo/discuss >> This list provided by the League of Professional System Administrators >> http://lopsa.org/ >> >> _______________________________________________ >> Discuss mailing list >> Discuss@lopsa.org >> http://lopsa.org/cgi-bin/mailman/listinfo/discuss >> This list provided by the League of Professional System Administrators >> http://lopsa.org/ >> > > _______________________________________________ Discuss mailing list Discuss@lopsa.org http://lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
