Cisco Aironet 1850 Series Deployment Manual page 47

What channel are you using?
If you are doing a Rate versus Range demo, it is important to choose your channel carefully. Obviously, you need to ensure that the
channel is clear. However, not all channels are created equal. Some channels have total output power restrictions. So, Cisco recommends
UNII-3 or UNII-2, over UNII-1 for best performance.
How far is the client from the access point?
Check how far is the client from the AP. 802.11ac introduces 256 QAM, which is a more complex modulation. So, the modulation
is harder to maintain over distance. If you want to consistently show 256 QAM, which equates to m8 and m9, it is recommended to
keep the client within 25'. Beyond 25', you will still see m8/m9, but not consistently.
Keep in mind, m7 is the same for 11n and 11ac, the difference being, 11ac allows for 80 MHz channels. Under ideal conditions, you
can expect 11ac to have an almost 3x gain over 11n at m9 and a 2x gain at m7.
How is the AP mounted?
AP placement needs to be considered. For close-in tests, less than 10', placement is not so important. Just make sure that the AP is
not obstructed. For other tests, you must take care to mount the AP in a proper location (ceiling or high on a wall in the right orientation).
Try to follow these best practices: avoid mounting the AP near metal, mount it horizontally on a ceiling, and so on.
What data rate is the AP transmitting to the client at?
It is often useful to monitor the data rate of the client. The data rate has a direct impact on performance. There are several ways to
monitor the data rate. The easiest method is to check on the GUI.
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