3Com 3CRWX120695A, 3CRWX440095A Configuration Manual page 196

196 C 8: C
HAPTER ONFIGURING
RF A -T
UTO UNING
Utilization, calculated based on the number of multicast packets per
second that a radio can send on a channel while continuously sending
fixed-size frames over a period of time.
Phy error count, which is the number of frames received by the MAP
radio that have physical layer errors. A high number of Phy errors can
indicate the presence of a non-802.11 device using the same RF
spectrum.
Received CRC error count. A high number of CRC errors can indicate
a hidden node or co-channel interference.
The thresholds for these parameters are not configurable.
RF Auto-Tuning also can change a radio's channel when the channel
tuning interval expires, if a channel that has less disturbance is detected.
Disturbance is based on the number of neighbors the radio has and each
neighbor's RSSI.
A radio also can change its channel before the channel tuning interval
expires to respond to RF anomalies. An RF anomaly is a sudden major
change in the RF environment, such as sudden major interference on the
channel.
By default, a radio cannot change its channel more often than every 900
seconds, regardless of the RF environment. This channel holddown avoids
unnecessary changes due to very transient RF changes, such as activation
of a microwave oven.
Tuning the Transmit Data Rate
A radio sends beacons, probe requests, and probe responses at the
minimum transmit data rate allowed for clients. This gives them the
maximum distance. All other packets are transmitted at a rate
determined by their destination. All packets are transmitted at the same
power level.
By default, the following minimum data rates are allowed:
5.5 Mbps for 802.11b/g clients
24 Mbps for 802.11a clients
As described in "Power Tuning" on page 195, a radio can lower the data
rate with a client in order to improve the connection with that client.