Cisco DPH650 User Manual page 23

Configure the DPH650
EDCA STA Parameters: Each station maintains a Contention Window (CW),
which is used to select the random back off counter. The BC is determined as a
random integer drawn from a uniform distribution over the interval (0, CW). The
CW size is initially assigned CWmin, and increases when a transmission fails,
i.e., the transmitted data frame has not been acknowledged. After any
unsuccessful transmission attempt, another back off timer is performed, with an
upper bound of CWmax. This reduces the collision probability in case there are
multiple stations attempting to access the channel.
CW min: Should be smaller for delay-sensitive data
CW max: Should be smaller for delay-sensitive data
AIFSN: Should be smaller for delay-sensitive data
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