How Many non overlapping Channels on 802.11N

[Face-Man]

Right I've heard that there are 9 non overlapping channels on 802.11N but I know from the stuff I've done on g that that only has 3 sets of 3 non overlaping ie 1,6,11 or 2,7,12 etc. As N use 40mhz rather than 20mhz how can it fit the extra channels in. Does it use the 5Ghz range in a unique way and how then can it then be compatible with g.

[GrumbleDook]

Pretty sure I read a Gartner report saying that the stuff about 21/9/3 etc was a heap of FUD or sales spin from some of the suppliers and that if a supplier says it can do it and can't then sue them. TechTarget also did a report around it last year looking at Trapeze, Aruba and Cisco ... (searchnetworking.techtarget.com)

[bio]

Wireless can indeed be a complex thing to understand. We are also in progress to create a wireless solution for our school so i have dug up some info. IF it aint correct then plese correct em guys

 

802.11a

Year 2000 - Speed 54Mbit - Operates in 5 Ghz band - One can have 23 non overlapping channels

 

802.11g

Year 2003 - Speed 54Mbit - Operates in 2,4 Ghz band - One can have 3 non overlapping channels (channel 1, 6 and 11)

 

802.11n

Year 2009 -Speed 300 Mbit - Operates in 2,4 Ghz and 5 Ghz band -

If 2,4 Ghz used still have 3 non overlapping channels (channel 1, 6 and 11)

If 5 Ghz used still have 23 non overlapping channels

The n draft uses the MIMO technique, this means that the normal 20Mhz channel is doubled to 40 Mhz. This doesn't mean that you'll have 2 times the number of non overlapping channels. IT assures twice the data transfer rate due to multiple antennas on your access points.

 

So what is wise for your school (according to our situation):

* Implement 802.11n access point in all classrooms. This means 2 x 802.11n capable accesspoints per classroom (due to low effectiverange = 10 meters)

* Enable 802.11a only in all classrooms (on the 802.11n Aps)

* Buy laptops/netbooks only thats is capable of 5 Ghz (and capable of legacy 802.11g)

* Implement 802.11g access points in hallways and corridors (why ? you don't need so many APs and they have a long effective range = 70 meters)

 

Hope it helps somehow

bio...

[_Adam_]

bio could be right, but I was under the impression there were only 4 available non-overlapping channels in 802.11n 5Ghz. Agree 2.4GHz is only 3.