Alvarion BreezeACCESS EZ AU-EZ System Manual page 125

Chapter 4 - Operation and Administration
without being preceded with RTS frames. Setting this parameter to a value larger
than the maximum frame size eliminates the RTS/CTS handshake for frames
transmitted by this unit.
The available values range from 20 to 4092 bytes.
The default value is 4092. It is recommended that this value be used to ensure
that RTS/CTS is never used in the AU.
4.2.6.5.2 Minimum Contention Window
The Minimum Contention Window parameter determines the time that a unit
waits from the time it has concluded that there are no detectable transmissions by
other units until it attempts to transmit. The system uses a special mechanism
based on detecting the presence of a carrier signal and analyzing the information
contained in the transmissions of the AU to estimate the activity of other SUs
served by the AU. The target is to minimize collisions in the wireless medium
resulting from attempts of more than one unit to transmit at the same time.
The system uses an exponential Back-off algorithm to resolve contention between
several units that want to access the wireless medium. The method requires each
station to choose a random number N between 0 and a given number C each time
it wants to access the medium. The unit will attempt to access the medium only
after a time equal to DIFS (for more details refer to
slots, always checking if a different unit has accessed the medium before. Each
time the unit tries to transmit and a collision occurs; the maximum number C
used for the random number selection will be increased to the next available
value. The available values are 7, 15, 31, 63, 127, 255, 511 and 1023.
The Minimum Contention Window parameter is the first maximum number C
used in the back-off algorithm. The higher the number of SUs served by the same
AU, the higher the Minimum Contention Window for each SU should be.
The available values are 0, 7, 15, 31, 63, 127, 255, 511 and 1023. A value of 0
means that the contention window algorithm is not used and that the unit will
attempt to access the medium immediately after a time equal to DIFS.
The default value is 15.
4.2.6.5.3 Maximum Contention Window
The Maximum Contention Window parameter defines the upper limit for the
maximum number C used in the back-off algorithm as described in Minimum
Contention Window above.
The available values are 7, 15, 31, 63, 127, 255, 511 and 1023.
The default value is 1023.
BreezeACCESS EZ AU-EZ
Section
106
Menus and Parameters
4.2.6.2.8) plus N time
System Manual