Trouble Shooting Guide

Axxcelera Broadband
Troubleshooting-Installing an RF link - 26 - Issue: 5.3.x
Rev 2
Acknowledgements received from the SU. These are generated by the SU when it receives a valid cell or
cells in the downstream portion of the frame.
9.1.3.2 TX
Acknowledgements transmitted by the AP. These are generated by the AP when it receives a valid cell or
cells from an SU in the upstream portion of the previous frame.
9.1.4 CELLS
CELLS are the number of ATM CELLS that have been transmitted from, or received by the MAC, and
carried by the RF link.
9.1.4.1 RX
RX cells are cells that are received by the AP from all SUs. These counts include duplicate cells (i.e. . the
relevant count is incremented every time a cell is received over the RF link, regardless of whether it is a
new cell, or a duplicate - one that was retransmitted by an SU and received more than once).
9.1.4.2 TX
TX cells are cells that are transmitted from the AP to all SUs. This count includes cell retransmissions (i.e.
the count is incremented every time a cell is sent over the RF link, regardless of whether it is a new cell, or
a retransmission).
9.1.5 tx
The tx is the number of ATM cells entering the MAC from the Helium processor, to be sent downstream on
the air interface. This does not include retransmissions: it is the number of unique cells that need to pass
over the air. This number may be significantly less that the CELL TX count (see above).
The aggregate downstream cell retransmission rate (i.e. average for all AP-SU links) can be calculated
approximately from the “tx” and “CELL TX” counts, as follows:
Aggregate Downstream Cell re-transmission rate = (( CELL TX – tx ) / tx ) x 100%
The result is dependent on the traffic to each SU. A value of 0% means that cells are only sent once, a
value of 100% means that on average each cell is sent twice, and a value of 500% means that every cell is
sent six times - the maximum.
Note – This formula is only valid for a large number of cells (minimum recommended = 10000), because
of a 64 cell buffer that can distort the cell re-transmission calculation for small numbers of cells.
9.1.6 inseq
The “inseq” count is the number of ATM cells that the UTOPIA interface has received from the MAC for
this MID (i.e. MID 0 for the AP). This number represents the number of unique, error-free ATM cells that
the AP has received in the correct sequence. For an AP this number should be close to the number of
CELL RXOK, although it will probably be slightly lower.
9.1.7 miss
The “miss” count represents the number ATM cells the UTOPIA interface has received with the sequence
number wildly out. These represent errors. The missed count is usually close to zero, and should be orders
of magnitude lower than the inseq count.