User's Manual

Menus and Parameters
4.2.6.5.1
res an
eless link
lue larger
ndshake for frames
ansmitted by this unit.
ailable values range from 20 to 4032 bytes.
ed that these values be used to ensure that RTS/CTS is never used in
4.2.6.5.2
ter determines the time that a unit
re no detectable transmissions
y other units until it attempts to transmit. The BreezeACCESS 4900 system
es 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 section 4.2.6.2.10
RTS Threshold
The RTS Threshold parameter defines the minimum frame size that requi
RTS/CTS (Request To Send/Clear To Send) handshake. Frames whose size is
smaller than the RTS Threshold value are transmitted directly to the wir
without being preceded with RTS frames. Setting this parameter to a va
than the maximum frame size eliminates the RTS/CTS ha
tr
The av
The default value is 60 bytes for SUs. For AUs the default is 4032. It is
recommend
the AU.
Minimum Contention Window
The Minimum Contention Window parame
waits from the time it has concluded that there a
b
us
) plus N time
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.
Operation and Administration
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