4. Web Management-Wireless and WAN Settings
57
AirLive AIRMAX5 User’s Manual
AC Type
The queue and associated priorities and parameters for transmission are as follows:
Data 0 (Best Effort, BE):
Medium priority queue, medium throughput anddel ay.
Most traditional IP data is sent to this queue.
Data 1 (Background, BK):
Lowest priority queue, high throughput. Bulk data
that requires maximum throughput and is not time-sensitive is sent to this queue
(FTP data, for example):
Data 2 (Video, VI):
High priority queue, minimum delay. Time-sensitive data
such as Video and other streaming media are automatically sent to this queue.
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.