3Com WX4400 3CRWX440095A, WXR100 3CRWXR10095A, WX1200 3CRWX120695A Power Tuning, Channel Tuning

Overview 313

Power Tuning

By default, the switch evaluates the scan results for possible power changes every 300 seconds (5 minutes), and raises or lowers the power level if needed.

If RF Auto-Tuning determines that a power change is needed on a radio, MSS ramps the power up or down until the new power level is reached. Ramp-up or ramp-down of the power occurs in 1 dBm increments, at regular time intervals. The default interval is 60 seconds and is configurable. The power ramp amount (1 dBm per interval) is not configurable.

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:

„Presence of active sessions.

By default, If the radio has active sessions, MSS does not change the channel. If the radio does not have any active sessions, MSS uses the remaining parameters to determine whether to change the channel.

„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.

„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.