Wilan LIBRA 5800 AP, User Manual

Page: 130 / 156

Appendix E: Bench Configuration Testing
130 Libra 5800 Series User Guide
6. In some cases antennas that are too close can cause high BER. To solve this problem adjust the
signal strength. If the antennas are placed too close together, the strong signal causes distortion
at the receiving unit. The RSSI number in the MAC Layer Statistics can tell you if the link is good.
R
Statistics measured at the Linktest remote (the other unit to the one
from which Linktest is being initiated.
L
Statistics measured at the Linktest local (the unit from which the
Linktest is being initiated)
RSSI
Received signal strength indicator. This should be above the receive
sensitivity for the modulation chosen
Fade Margin
Number of dB by which the received signal strength exceeds the
minimum receiver sensitivity. The year round link availability depends
on the Fade Margin. Ensure that you have sufficient FM for the range
specified (see
Appendix C: Simple Link Planning Worksheet, page
117 for calculation of Fade Margin).
BER(1E6)
Bit error rate before forward error correction. 1E-6 is the default. The
tester can configure this. The ideal value is zero for the default setting.
FEC Corrected
Byte errors that were corrected by forward error correction. Ideally,
this should be zero, but 100,000 could be tolerated at RSSI = -75 to
meet a BER of 1E-6.
Missed Frames
The number of frames sent to, but not received by, the Linktest local.
Ideally, this number should be zero. The key numbers are the BER
and the FEC Corrected Bytes.
Loopback
Frames
The number of frames received by the local. This should be 781,
using the default setting of 1E-6. It changes according to the accuracy
specified in the Linktest.
wilan> linktest 2
Linktest symbol changes every 781 frames
RSSI FadeMargin BER(x1E6) FEC corrected Missed Loopback
R L R L R L R L Frames Frames
----- ----- ----- ----- ----- ----- ----- ----- ----- -----
-60 -60 43 43 0 0 0 0 0 781
-60 -60 46 43 0 0 0 0 0 781
-60 -60 46 43 0 0 0 0 0 781
-60 -60 46 22 0 0 0 0 0 781
-60 -60 46 43 0 0 0 0 0 781
-60 -60 43 43 0 0 0 0 0 781
-60 -60 46 43 0 0 0 0 0 781
-60 -60 46 43 0 0 0 0 0 781