Specifications

Chapter 4 - Operation and Administration Menus and Parameters
BreezeACCESS 4900 132 System Manual
The Adaptive Noise Immunity (ANI) mechanism is designed to reduce the wireless
physical layer errors and by that enhance the processing power of the unit,
delivering higher packet processing efficiency.
This ANI mechanism is triggered by the rate of detected Physical Errors and it is
modifying different thresholds affecting the immunity to specific interference
types.
This feature, active by default, exists in all units with HW revision C and higher
running SW version 3.0 and higher. Starting in SW version 4.0, the processing
power of the system has been increased dramatically. When using version 4.0 the
units are capable to process more packets per seconds, including physical error
packets. As a result, the ANI mechanism (triggered by the number of received
error packets) may not function properly in certain scenarios, resulting in link
performances that are far below the expectations. The option of manually
controlling the various parameters used by the ANI mechanism enables to achieve
optimal performance in certain deployments where the automatic ANI mechanism
may not function properly.
It is strongly recommended to consult with Alvarion's experts before switching to
manual mode and modifying any of the parameters.
The general rules for using the Noise Immunity Control parameters are:
In the SU, if performance (Modulation Level) is lower than expected based on the
SNR, try switching to Manual mode without changing any of the parameters.
In the AU, try switching to Manual mode if overall throughput is too low or if SUs
are lost although communication conditions are sufficient for good connectivity.
In many deployments the transition to Manual mode is sufficient. If not, you may
try changing the Noise Immunity Level and/or Spur Immunity Level parameters.
The target is to reduce the amount of Phy Error rate reported by the unit (see
Total Rx events in section “WLAN Counters” on page 94). To ensure that
sensitivity is not reduced too much and SUs are not lost, verify that the Age (see
Display Association Info in section “MAC Address Database in AU” on page 100)
of all SUs is below 20 seconds.
Do not activate the OFDM Weak Signal parameter if the SNR is below 36 dB.
Under normal conditions, the OFDM Weak Signal should never be activated in the
AU, since the SNR of all SUs will be below 36 dB when ATPC is enabled.
CAUTION
Do not change any of the SU's Noise Immunity Control parameters (except the Noise Immunity
State Control) from remote, as it may result in loss of connectivity to the unit.