User manual

Chapter 2 - Managing a Single Device/Cell Air Interface General Page
AlvariCRAFT Device Manager 42 User Manual
2.3.5 Noise Immunity Parameters
Noise Immunity parameters are available only for units with HW Revision C and
higher, except to Pulse Detection Sensitivity that is available also for units with
HW Revision B.
The Adaptive Noise Immunity (ANI) mechanism is designed to reduce the wireless
physical layer errors and by that enhance the processing power of the AU/BU,
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 or
higher, 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/RB, 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/BU, try switching to Manual mode if overall throughput is too low or if
SUs/RB 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 “Site Survey Rx/Tx Counters Page” on page 85). To ensure that
sensitivity is not reduced too much and SUs are not lost, verify that the Age of all
CAUTION
Do not change any of the SU's/RB’s Noise Immunity Control parameters (except the Noise
Immunity State Control) from remote, as it may result in loss of connectivity to the unit.