User's Manual

Menus and Parameters
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BreezeACCESS 4.0 System Manual
The default is the minimum possible rate, 1Mbps.
! Multi-Rate – Link quality dynamically changes, due to various
environmental conditions. Dynamically switching between the
possible transmission rates increases the probability of using the
maximum rate for the current radio link quality at any given
moment. Decreasing the rate one step improves the receiver
sensitivity by 6-8dB. When enabled, the transmission rate decisions
are made separately for each unit. This algorithm is completely
separated from the retransmission mechanism defined by Number
of Retransmission and Number of Dwells to Retransmit
parameters. The algorithm provides Access Units with
simultaneous, adaptive support for multiple Subscriber Units at
different rates. The decision on the rate of each transmission (first
attempt) is based on counting transmissions, retransmissions and
successful windows. A window is defined as N consecutive
transmission or retransmission attempts, defined by the Multi-Rate
Decision Window Size parameter. A successful window is a window
in which the number of failed transmissions is not higher than a
defined threshold. A transmission is defined as failed if an ACK was
not received after the first transmission of a frame. If the current
rate is lower than the maximum available rate, the transmission
rate will be increased to the next available rate following a
successful window. If the current rate is higher than the minimum
available rate (1 Mbps), the transmission rate will be decreased to
the next available rate following a failed window. The Multi-Rate
menu includes the following parameters:
" Multi-Rate Support – Enables or disables the Multi-Rate
decision algorithm. When enabled, the algorithm supports
increase/decrease of transmission rates in the range from
1 Mbps to the current value of the Maximum Data Rate
parameter. (Enabling the algorithm has no effect if the
Maximum Data Rate is 1 Mbps).
The default selection is Enable.
" Multi-Rate Decision Window Size – Sets the size of the
decision window. The size of a window is measured as the
number of consecutive transmission or retransmission
attempts. Increasing the size of the window will increase the
probability that it will be a successful window, thus slowing
down the decision to degrade to a lower rate and accelerating
the decision to upgrade to a higher rate.
Valid values are from 1 to 50.
The default value is 12.
" Number of Failures in Multi-Rate Decision Window – Sets
the maximum number of failures allowed in a decision
window. A window is defined as successful only if the
number of failures is not higher than this number. A
transmission attempt is defined as a failure if an ACK was
not received upon the first transmission attempt. Increasing