D-Link DWC-1000 User Manual page 116

Section 4 - Advanced WLAN Configuration
Field
cwMan (Maximum
Contention Window)
Max. Burst
WMM Mode
Queue
AIDS (Inter-Frame Space)
cwMin (Minimum
Contention Window)
D-Link DWC-1000 User Manual
The value specified here in the Maximum Contention Window is the upper limit (in
milliseconds) for the doubling of the random backoff value. This doubling continues until
either the data frame is sent or the Maximum Contention Window size is reached.
Once the Maximum Contention Window size is reached, retries will continue until a
maximum number of retries allowed is reached.
Valid values for the cwmax are 1, 3, 7, 15, 31, 63, 127, 255, 511, or 1024. The value for
cwmax must be higher than the value for cwmin.
AP EDCA Parameter Only (The Max. Burst Length applies only to traffic flowing from the
access point to the client station.) This value specifies (in milliseconds) the Maximum Burst
Length allowed for packet bursts on the wireless network. A packet burst is a collection
of multiple frames transmitted without header information. The decreased overhead
results in higher throughput and better performance. Valid values for maximum burst
length are 0 through 999.
General Parameters
Wi‐Fi MultiMedia (WMM) is enabled by default. With WMM enabled, QoS prioritization
and coordination of wireless medium access is on. With WMM enabled, QoS settings on
the D‐Link controller control downstream traffic flowing from the access point to client
station (AP EDCA parameters) and the upstream traffic flowing from the station to the
access point (station EDCA parameters).
Disabling WMM deactivates QoS control of station EDCA parameters on upstream traffic
flowing from the station to the access point. With WMM disabled, you can still set some
parameters on the downstream traffic flowing from the access point to the client station
(AP EDCA parameters).
To disable WMM extensions, switch OFF.
To enable WMM extensions, switch ON.
Station EDCA Parameters
Queues are defined for different types of data transmitted from station‐to‐AP:
• Data 0 (Voice)—Highest priority queue, minimum delay. Time‐sensitive data such as
VoIP and streaming media are automatically sent to this queue.
• Data 1(Video)—Highest priority queue, minimum delay. Time‐sensitive video data is
automatically sent to this queue.
• Data 2 (best effort)—Medium priority queue, medium throughput and delay. Most
traditional IP data is sent to this queue.
• Data 3 (Background)—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).
The Arbitration Inter‐Frame Spacing (AIFS) specifies a wait time for data frames. The wait
time is measured in slots. Valid values for AIFS are 1 through 255.
This parameter is used by the algorithm that determines the initial random backoff wait
time (window) for data transmission during a period of contention.
The value specified in the Minimum Contention Window is the upper limit (in milliseconds)
of a range from which the initial random backoff wait time is determined.
The first random number generated will be a number between 0 and the number
specified here.
If the first random backoff wait time expires before the data frame is sent, a retry counter is
incremented and the random backoff value (window) is doubled. Doubling will continue
until the size of the random backoff value reaches the number defined in the Maximum
Contention Window.
Description
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