D-Link DWS-1008 User Manual page 203

DWS-1008 User's Manual
Channel and Power Tuning
RF AutoTuning can change the channel or power of a radio, to compensate for RF changes
such as interference, or to maintain at least the minimum data transmit rate for associated
clients. A radio continues to scan on its active data channel and on other channels and
reports the results to its switch.
Periodically, the switch examines these results to determine whether the channel or the
power needs to be changed.
Power Tuning
By default, the switch evaluates the scan results for possible power changes every 300
seconds (5 minutes), and raises or lowers the default power level if needed.
A radio can temporarily increase its power level from the default at any time to correct either
of the following client-related symptoms:
• Increase in the number of duplicate packets received from a client. This symptom
indicates that the AP radio's acknowledgements (ACKs) are not reaching the client.
• Increase in the number of retransmissions of unicast packets from the radio to a
client.
The radio uses two methods to treat these symptoms. First, if the data rate at which the radio
is sending packets to the client is above the minimum data rate allowed, the radio lowers the
unicast data rate with the client down to the next valid rate.
If the retransmissions still exceed the threshold, the radio continues to lower the data rate,
one setting at a time, until either the retransmissions fall under the threshold or the minimum
allowed data rate is reached.
If the retransmissions still exceed the threshold after the minimum allowed data rate is
reached, the radio increases power by 1 dBm. The radio continues increasing the power in
1 dBm increments until the retransmissions fall to or below the threshold.
After the retransmissions fall to or below the threshold, the radio reduces power by 1 dBm.
As long as retransmissions remain within the allowed threshold, the radio continues reducing
power in 1 dBm increments until it returns to its default power level.
Channel Tuning
By default, the switch evaluates the scan results for possible channel changes every 3600
seconds (1 hour). MSS uses the following parameters to determine whether to change the
channel on a radio:
• Received signal strength indication (RSSI)
• Amount of noise on the channel
• Packet retransmission count, which is the rate at which the radio receives
retransmitted packets.
D-Link Systems, Inc.
Configuring RF Auto-Tuning
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