AirLive A.DUO - Manual (Page 68)

4. Wireless and WAN Settings
61 AirLive A.DUO User’s Manual
Data 3 (Voice, VO): Highest priority queue, minimum delay. Time-sensitive
data such as Voice over IP (VoIP) is automatically sent to this queue.
Packets in a higher priority queue will be transmitted before packets in a lower
priority queue.
ECWmin and ECWmax
If an access point detects that the medium is in use, it uses the DCF random backoff
timer to determine the amount of time to wait before attempting to access a given
channel again. Each access point waits some random period of time between retries.
The wait time (initially a random value within a range specified as the Minimum
Contention Window increases exponentially up to a specified limit Maximum
Contention Window.
The random delay avoids most of the collisions that would occur if multiple APs got
access to the medium at the same time and tried to transmit data simultaneously. The
more active users you have on a network, the more significant the performance gains
of the backoff timer will be in reducing the number of collisions and retransmissions.
The random backoff used by the access point is a configurable parameter. To describe
the random delay, a "Minimum Contention Window" (ECWMin) and a "Maximum
Contention Window" (ECWMax) is defined.
ECWmin: The value specified for the Minimum Contention Window is the
upper limit of a range for the initial random backoff wait time. The number
used in the random backoff is initially a random number between 0 and the
number defined for the Minimum Contention Window.