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 in Windows 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 PHY rate.
The PHY rate directly affects
the throughput rate, which is the average speed at which the client
and AP can exchange application-level data, such as files. The
throughput rate is always lower than the PHY rate, typically by
more than 50%, due to a number of factors, such as protocol
overheads and retransmissions. A low PHY rate always means low data
throughput and therefore poor WLAN performance.
The PHY rate is shown for the
AP that has the strongest signal in the given map area among the
APs selected for analysis. This mimics the roaming behavior of
client adapters that connected to the strongest AP. While other
audible APs may offer higher PHY rates, a typical adapter will
connect to the AP with the strongest signal. You can deselect one
or several of the selected APs to see PHY rate values for less
Expected PHY rate calculations
are based on signal strength and use a table that maps signal
levels to PHY data rates. The table uses average values for common
adapter types. 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 used.
Double-clicking on the Expected
PHY rate legend on the status bar allows you to configure the color
When low expected PHY rate
areas are discovered, the following solutions are suggested:
||Increase the signal level, as it is
directly related to the PHY rate. See the suggested solutions for
increasing signal level in the
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.
are using legacy 802.11 a/b/g equipment, consider upgrading to
802.11n or 802.11ac.