User Manual

Table Of Contents
Chapter 4 - Operation and Administration
BreezeACCESS VL System Manual
182
Burst Mode option will be “blocked” upon trying to enable it when using WEP for
data encryption. This limitation does not apply to units with HW Revision C.
NOTE
The Burst Mode parameters are not applicable when the Wireless Link Prioritization Option is
enabled.
4.2.6.5.8.1 Burst Mode Option
The Burst Mode Option enables or disables the Burst Mode operation.
The default is Enable.
4.2.6.5.8.2 Burst Mode Time Interval
The Burst Mode Time Interval defines the burst size, which is the time in which
data frames are sent immediately without contending for the wireless medium.
The range is 1 to the value of the Maximum Burst Duration defined for the Sub-
Band.
The default is 5 milliseconds or the value of Maximum Burst Duration defined for
the Sub-Band (the lower of the two values).
4.2.6.5.9 Adaptive Modulation Algorithm (M ult i Ra t e )
The Adaptive Modulation Algorithm enables adapting the modulation level of
transmitted data to the prevailing conditions of the applicable radio link. The
algorithm provides Access Units with simultaneous, adaptive support for multiple
Subscriber Units at different modulation levels, as transmission’s modulation
level decisions are made separately for each associated SU.
Link quality fluctuates due to various environmental conditions. Dynamically
switching between the possible modulation levels increases the probability of
using the maximum modulation level suitable for the current radio link quality at
any given moment.
The decisions made by the Adaptive Modulation Algorithm for the modulation
level to be used are based on multiple parameters, including information on
received signal quality (SNR) that is received periodically from the destination
unit, the time that has passed since last transmission to the relevant unit, and
the recent history of successful and unsuccessful
transmissions/retransmissions. In the AU the decision algorithm is performed
separately for each SU.
The transmission/retransmission mechanism operates as follows:
1 Each new frame (first transmission attempt) will be transmitted at a
modulation level selected by the Adaptive Modulation algorithm.