User guide

550
pmp-0229 (Mar 2013)
Reviewing the Link Status Tool Results (AP) Using Tools in the GUI
Figure 188: Link Status tab of AP, example
The Link Status tool results include values for the following fields.
Power Level
Jitter
These are reported near-instantaneously, if web refresh rate is set to 1 or 2 seconds. These values
are the same as those that are displayed on the Session Status tab of the Home page in the AP and
the General Status tab of the Home page in the SM.
Last Link Test Efficiency Percentage
This field displays the results of the last link test initiated from the SM. Link tests initiated from
the AP are not shown. A link test exercises both uplink and downlink, and efficiencies for both are
reported.
BER Results
This field displays the over-the-air Bit Error Rates for each downlink. (The ARQ [Automatic
Resend reQuest] ensures that the transport BER [the BER seen end-to-end through a network] is
essentially zero.) The level of acceptable over-the-air BER varies, based on operating
requirements, but a reasonable value for a good link is a BER of 1e-4 (1 x 10
-4
) or better,
approximately a packet resend rate of 5%.
BER is generated using unused bits in the downlink. During periods of peak load, BER data is not
updated as often, because the system puts priority on transport rather than on BER calculation.
Registration Requests
Re-registration Requests
These request counts are shown for each SM since the time of the last AP reboot. A Registration
Requests count is the number of times the SM registered after the AP determined that the link had
been down. A Re-registration Requests count is the number of times the AP received an SM
registration request while the AP considered the link to be still up (and therefore did not expect
registration requests).