User's Manual

2-56
BreezeACCESS 4.0 Operations and Administration
Manual Revision: 1.01
! Number of Retransmissions to Decrease Rate – The number of
unsuccessful retransmissions that will cause an automatic decrease
in the data rate before the next retransmission (the lower the data
rate, the higher the probability that the packet will be properly
received and acknowledged).
Valid values are from 0 to 10.
The default value is 0, meaning that the rate will be decreased
immediately following an unsuccessful transmission attempt at the
current rate.
! Minimum Contention Window – The BreezeACCESS system uses a
special mechanism based on detecting the presence of a carrier
signal (Carrier Sense Multiple Access-CSMA) and analyzing the
information contained in the transmissions of the AU to estimate
the activity of other SUs served by the same AU. The target is to
minimize collisions in the wireless media resulting from trials of
more than one unit to transmit at the same time. The contention
window is the time that a unit will wait from the time it has decided
that there are no transmissions by other units until it will attempt
to transmit. The contention window is a random number whose
maximum value is determined by the value of the Minimum
Contention Window parameter and the number of previous trials
to transmit the frame. The higher the number of SUs served by the
same AU, the higher the Minimum Contention Window for each SU
should be.
The Valid values are from 7 to 255.
The default value is 31.
! Carrier Sense Level – This is the threshold level that determines
the existence of transmission from another unit on the wireless
media. As long as the level is above this threshold, the unit will
assume that another unit is transmitting and will refrain from trying
to transmit in order to prevent collisions.
The default value is -85 dBm
! Maximum Multicast Rate (AU only)– Determines the maximum
rate of multicast and broadcast transmissions. Multicast and
broadcast transmissions are not acknowledged; therefore there is a
chance that such transmissions will not be properly received
without the possibility of using the acknowledgement mechanism
for retransmission. Therefore, it is recommended to use a lower rate
for transmission of broadcast, multicast and control frames, to
increase the probability that they will be received without errors.
The available selections are 1, 2, and 3 Mbps.
NOTE:
The Number of Dwells to Retransmit is not applicable to ACSE voice frames since
voice is sensitive to delay. All ACSE voice frames will be retransmitted within the same
dwell, up to the maximum number of retransmissions allowed as defined by the ACSE
Number Of Retransmissions For Voice parameter.