User's Manual

Menus and Parameters
2-37
BreezeACCESS 4.0 System Manual
BreezeACCESS units operate at data rates of 3 Mbps, 2 Mbps,
1 Mbps. Under certain conditions (compatibility reasons or range/
speed trade-off), you may decide to limit the use of higher rates. If
the quality of the link is not good enough, it is recommended to
decrease the value of this parameter (the higher the data rate, the
higher the error rate). Otherwise, there is a high probability that the
unit will have to retransmit many frames several times before
temporarily reducing the data rate (see Number of
Retransmissions to Decrease Rate on page 2-56). A high number
of retransmissions reduces the overall throughput for the selected
SU as well as for all the other SUs served by the same AU. It is
recommended to also configure the Maximum Data Rate
parameter when the Multi-Rate mechanism is enabled, to avoid
unnecessary trials to transmit at higher rates when the probability
of successful transmissions at these rates is low.
The link quality can be estimated based on the RSSI measurement
in the SU, indicating the level at which the SU receives
transmissions from the AU (downlink RSSI). If the measured RSSI is
less than a certain threshold, it is recommended to decrease the
Maximum Data Rate of the SU in accordance with Table 2-8
(including a 3 dB safety margin). For best results it is recommended
to also acquire the RSSI results from the AU, indicating the level at
which the AU receives transmissions from the specific SU (uplink
RSSI), and to use the lower of the two numbers.
The AU learns the Maximum Data Rate used by each SU during the
association process, and uses this rate for transmissions to the
specific SU.
Allowed values are 1, 2, 3 Mbps.
The default value is 3 Mbps.