The physical layer (PHY) rate is the speed at which client devices
communicate with the AP. When you move a computer connected to the
AP within the WLAN coverage area, the adapter properties dialog on
Windows or the Wi-Fi icon menu on macOS displays the varying
connection speed, which may be as high as 450 or 300 Mbps when you
are close to the AP or as low as 1 Mbps when you are 50 meters away
from it. The displayed speed is the actual PHY rate at which the
client was connected to the AP during an active survey.
This is unlike the
available for passive surveys, where the PHY rate is not measured,
but rather estimated based on the signal level. The actual PHY rate
that you observe may be lower or higher than the expected rate,
depending on the specific adapter and AP equipment being
The PHY rate that is measured is the rate at which the adapter is
connected to the AP at any given spot along the survey path. As you
move along the path, the adapter typically roams to the AP that
provides the strongest signal within your WLAN.
It is important to remember that some adapters let you adjust
roaming thresholds; these roaming settings might affect the roaming
behavior and, therefore, the measured PHY rate. For example,
consider two APs located 20 meters away from each other with the
signal level ranging from -30 dBm next to the APs to -70 dBm in the
middle of the distance between the APs. As you walk from the first
to the second AP, some clients will roam as soon they pass the
middle point, while others will not roam until they are only a few
meters away from the second AP. For this reason, the PHY rate
visualization is heavily dependent upon one's walkabout path and
its direction. Walking from the first to the second AP might
produce a picture that would be different from the one produced by
walking in the opposite direction.
Double-clicking on the Actual PHY rate legend on the status bar
allows you to configure the color scheme and change its value
When low actual PHY rate areas are discovered, the following
solutions are suggested:
Verify that the set of supported rates and standards of the adapter
being used for active surveys is at least as good as that of the
Low PHY rates might be caused by non-aggressive roaming. Check the
adapter roaming settings and repeat the survey in the questionable
zones. Try to walk very slowly to give the adapter time to roam and
establish a good quality link to the AP.
Increase the signal level, as it is directly related to the PHY
rate. See the suggested solutions for increasing signal level in
the Signal Level
Check your AP capabilities. If you are using newer 802.11n
equipment, make sure that the maximum MCS indices, Short GI, and 40
MHz channel bandwidth are allowed in the device configuration.
If you are using legacy 802.11 a/b/g equipment, consider upgrading
to 802.11n or 802.11ac.