Trouble Shooting Guide

Axxcelera Broadband
Troubleshooting-Installing an RF link - 21 - Issue: 5.3.x
Rev 2
backoff, and the AP and SU having the same channels.conf file (where applicable). A very high value here
can also indicate a hardware fault.
7.1.25 Downlink RSSI Fade Margin
The Downlink RSSI fade margin is the amount by which the RSSI can fall (in dB) before the radio link will
fail totally. The minimum fade margin recommended by Axxcelera is 10dB, although units at maximum
range will have slightly less than this at best. Although the radio link will still work, the RF error rates rise
sharply when the fade margin drops below approximately 5dB. Operating SUs with a fade margin below
10dB may compromise the quality of the radio link in a noisy environment.
7.1.26 TX maximum backoff
TX maximum backoff displays the maximum system backoff that can be placed in the system.conf file for
a given band.
7.1.27 TX current backoff
TX current backoff displays the system backoff that is currently in the unit. This number is defined by the
value set in the system.conf file. Axxcelera recommend that the AP and all SUs in a sector have the same
backoff value.
7.1.28 Max TX power for channel
Max TX power for channel displays the maximum power in dBm that can be transmitted from the radio.
The power limits set by the FCC are; high band = +14dBm, mid band = +8dBm, low band = +1dBm.
7.1.29 Actual TX power
Actual TX power is the power level that the radio is actually transmitting at. For an SU it is dependent on
the received signal strength (inversely related to RSSI), and can be anything from the Max TX power value
down to 58dB below the Max TX power. The value will fluctuate over time with changes in RSSI. If the
Actual Tx power rises to within 2dB of the Max TX power then the RSSI on the SU is probably too low,
and the upstream radio link may be unreliable at times.
7.1.30 Averaging MAC error rates over <period>
Averaging MAC error rates over <period>, displays the number of seconds during which the MAC stats are
calculated. The default is 2 seconds, but this can be changed by adding the number of seconds desired to
the link status command (i.e. “link status 10”). Be careful not to put to large of number here because the
console is locked while these calculations are taking place.
7.1.31 Downlink Header Error Rate
Downlink Header Error Rate is the FDHDR (Frame Descriptor Header) error rate for a specific AP-SU
radio link. This is displayed in % and is based on FDHDR RXOK, RXMISSED, and RXBAD from the
SU’s MAC stats. It is only applicable to SUs. It is followed by an indicator to tell you if the error rate is
acceptable. A high FDHDR error rate indicates a downstream radio problem between the AP and this
specific SU. It may be caused by a problem with received signal strength or quality, or a problem with the
AP transmitter or SU receiver.