What are the 5Ghz non-DFS, non-overlapping channels?

[Laura4]

What are the 5Ghz non-DFS, non-overlapping channels?

[hsachse]

Sometimes using only 20 Mhz channel for both frequency band make the connections more stable. Older iPads and iPhones (other tablets/smartphones, too) only have 2,4 GHz radios so they could only use 802.11g/n. To save battery energy many mobile device have only 1x1:1 MIMO wifi module and only support 20 MHz channels. So this devices have a max PHY rate of 150 mbps (around 65-75 mbps throughput in reality). This bandwidth is shared by all clients connected to this radio.

But the connection drops sounds like another problem. Maybe and non-wifi interferer like bluetooth. Do you have a spectrum analyser for troubleshooting?

[Laura4]

I don't see neighboring APs on the same channel either.

[Laura4]

We use Enterasys 3605 APs. Most of the schools, Radio 1 is set to 40MHz and Radio 2 is set to 20MHz. But at one school, I noticed both radios were set to 20MHz, Not sure why, but I changed it to see if it improves anything. We have an Enterasys AP in most classrooms above the ceiling tile in the center of the room, so that seems like plenty of coverage, but we still get teachers complaining that there wifi connection drops when using iPads, or cannot mirror to an Apple TV from their Ipad or macbook air. Sometimes when teachers try to mirror to their Apple TV, it doesn't show up in the list as an option.

[hsachse]

Thats right. In this case you bond channels to 40 MHz channels with the upper channel selected as second channel. This results in bonding of channel 36 with 40, 44 with 46, 149 with 153 and 157 with 161. This creates a 4 channels (like a 4 channel plan) usable to develop a non-overlapping channel sheme.

Any reasons why you don't want use DFS channels? If you need smaller cell size design (voice over wifi or high density setup require this) using all available channels is i most case required to prevent channel overlapping. I some case using only 20 MHz channels even for 802.11a/n (5 GHz) is needed for scalability and higher performance even with a lower max. PHY rate thats possible with 20 MHz.

What application do you design your wifi for?

[Ronald_Dvorak]

Here another slide that illustrate how channel width affects the available non-overlapping channels...