Different brand have their algorithm and patented technology deal with radio resource management.
That's why you pay a lot for WLC rather than a Linksys.
If you talking about the exact logic that how does Cisco's WLC perform DCA, I think there is no public document would describe it.
But I believe you may have a general idea from the RRM White Paper.
1. Same Channel Contention—other AP's/clients on the same channel - also known as Co-Channel
interference or CCI
2 Foreign Channel - Rogue—Other non RF Group AP's operating on or overlapping with the AP's served
channel
3 Noise—Non-Wi-Fi sources of interference such as Bluetooth, analog video, or cordless phones - see
CleanAir for useful information on using CleanAir to detect noise sources
4 Channel Load—through the use of industry standard QBSS measurements - these metrics are gathered
from the Phy layer - very similar to CAC load measurements.
5 DCA Sensitivity—A sensitivity threshold selectable by the user that applies hysteresis to the evaluation
on channel changes
The impact of each of these factors is combined to form a single RSSI based metric known as the Cost Metric
(CM). The CM then represents complex SNIR of a specific channel and is used to evaluate the throughput
potential of one channel over another. The goal is to be able to select the best channel - for a given AP/Radio
while minimizing interference
