3Com WXR100 3CRWXR10095A, WX4400 3CRWX440095A, WX1200 3CRWX120695A manual How Channels Are Selected

312CHAPTER 14: CONFIGURING RF AUTO-TUNING

During radio operation, MSS periodically reevaluates the channel and changes it if needed. (See “Channel Tuning” on page 313.)

„Initial power assignment—The MAP sets a radio’s initial power level to the maximum value allowed for the country code (regulatory domain). In a deployment with few MAPs, the radio remains at maximum power. Otherwise, the radio reduces power until the power is just enough to reach the MAP’s nearest neighbor that is on the same channel.

How Channels Are Selected

When a radio first comes up, if RF Auto-Tuning for channels is enabled, the initial channel selected will follow a uniform distribution of channels that spans the list of channels, rather than selecting the next sequential channel number.

For example, the range of valid channels for 802.11a radios in the US is as follows:

36, 40, 44, 48, 149, 153, 157, 161

On each WX, the first channel chosen will be random. Assuming that channel 60 is the first channel selected, the order of the channel selections will be as follows:

Order:	2	5	8	3	6	1	4	7
Channel:	40	44	48	52	56	60	64	68

After these initial 8 channel selections are chosen, the pattern will repeat itself.

Channel and Power RF Auto-Tuning can change the channel or power of a radio, to Tuning 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 WX switch.

Periodically, the switch examines these results to determine whether the channel or the power needs to be changed.