View Full Version : why there are few 11n AP?
As far as I know, there's so few AP in the market that use 802.11n.Why?Cuz now I need a wireless link more than 100Mbps~
Is it the reason that 11n is hard to design MIMO directional antenna?
Because 802.11n is pretty much useless for an access point more than a few hundred feet to the client. Much in the same way your eyes loose stereo resolution after a hundred feet or so.
Because 802.11n is pretty much useless for an access point more than a few hundred feet to the client. Much in the same way your eyes loose stereo resolution after a hundred feet or so.
Hi WHT
So you mean 11n's algorithm limits its owm long-distance performance?
No, not really...
802.11n uses the MIMO approach...a three antenna improvement over the long haul two antenna approach with the antenna separated by as much as twenty feet or more.
Granted antenna diversity only requires two antenna to be separated by a quarter wavelength apart, but practical experience has show an several magnitudes of quarter wavelength separation is necessary for long haul applications.
http://telecomanddata.com/tower_293.jpg
Generally speaking, antenna separation should be 60-80 feet at 2 Gig, 45-50 feet at 4 Gig, 30-40 feet at 6 Gig and 25-30 feet at 11 Gig.
So....at 2.4 Gig, you need 60-80 feet for effective antenna diversity for carrier grade long haul applications.
At short ranges (less than a few hundred feet), a two or three quarter wavelength is effective...but that effectiveness rapidly disappears past that point.
This can be referenced back to Arvids Vigant (Telos Corp.) and his paper, "Technical Line of Sight Path Reliability" 1992, published by U.S. Army, Command, Control and Communications Systems Directorate, Fort Monmouth, New Jersey.
Now....did you REALLY wanna know all that ????
sukhoff
12-16-2008, 12:31 AM
what about indoor use of 11n?
The reality is a that "N" is all about speed, not distance. It all depends how the industry wants to spin the idea. It is a significant improvement for indoor applications.
