The best practice I've seen is to add 11a to high density areas. There's no substitute for using more spectrum, and there are typically enough 11a clients around to make a difference. (Beware that not all clients do a good job of choosing 11a over 11b/g.)
I considered using the 4 channel plan for a similar scenario until I read that it is better suited for low user density deployments, but not high density. I have seen it used successfully for low density. -Tim Tim Callahan Lead Engineer for Mobility and Wireless University of Michigan 4251 Plymouth Road Ann Arbor, MI 48105 O: 734-763-9640 From: Chuck Enfield [mailto:[EMAIL PROTECTED] Sent: Thursday, February 21, 2008 7:02 PM Subject: Re: Using 4 channels rather then 3 for the 2.4ghz wifi Hi Nick, I have no problems with four channels for 802.11g, but you have to be careful with it. The benefit of four channels is added throughput gained by 33% more APs being able to talk at the same time. The trade-off is increased errors due to simultaneous transmissions on overlapping channels. The closer together your APs and the denser your client population, the more errors you will get. Turning down the AP power will help, but not much. There will still be 100 client radios blasting away at 20mW. If your room is a typical size for 150 seats, then I think your APs are probably too close together to benefit from four 802.11g channels. I would be surprised if your error rates in such a scenario would be less than 10%, and I would expect even higher. Many things would still work under those conditions, but all the retries would negate most, if not all, of the potential benefit.. Also, error rates that high can foul some stuff up. For example, VPN sessions start dropping unexpectedly at error rates above 5%. Streaming content is also likely to have problems. Now that I advised you against it, I hope you would consider giving it a try. I would love to hear how it works out. If you're available to monitor the network after you make the change, you can always put it right back if things don't work out. Of course it depends on how well your users would tolerate a brief period of degraded performance. Chuck Enfield Sr. Communications Engineer Penn State University Telecommunications & Networking Services 110 USB2, UP, PA 16802 Ph. (814) 863-8715 Fx. (814) 865-3988 ________________________________ From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Urrea, Nick Sent: Thursday, February 21, 2008 3:04 PM To: [email protected] Subject: [WIRELESS-LAN] Using 4 channels rather then 3 for the 2.4ghz wifi We have a large study room at UC Hastings which accommodates up to 150 students. On average I see about 80-100 users using the wifi in the room. To load balance the wifi in the room I have setup 4 APs. Right now we use the 3 non-overlapping 2.4ghz channels, 1, 6, and 11. The 4 APs are line of sight with each. Do you think it would be a good idea to go to 4 channels instead 3 Ex: (1, 4, 8, 11) ---- Nicholas Urrea Information Technology UC Hastings College of the Law [EMAIL PROTECTED] x4718 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
