User's Manual

11 Monitoring the Network
APCD-LM043-4.0 131
11.2 CCU Receive Statistics
Similar to the case for CCU transmit statistics, there are several key CCU receive statistics
that you can use to monitor on-going performance of the CCU radio network. When the CCU
sends a directed poll to an EUM, it expects to get an acknowledgement. The following results
have been taken from a live CCU using the <stats mac> command:
Table 28 Typical CCU Receive Statistic
From these statistics:
Total number of replies expected = A + B + D = 434,882
and the receive packet error rate which, as noted in Table 28, includes EUM receive errors and
errors associated with random access attempts, is given by
RxPER= (B+C+D)/(A+B+D)=(2,464+192+22,688)/434,882=5.8%
One other receive statistic that is important in multi-CAP environments where frequency re-
use is implemented is rxPktsNoMatch. A high value of rxPktsNoMatch indicates that the two
CCU radio environments are interfering with each other.
The statistic rxPktsDuplicate measures the number of times the EUM sends the same packet
of information more than once. A high value of rxPktsDuplicate indicates that the
acknowledgements from the CCU are not being properly received at the EUM.
Statistic Description Sample
A rxPktsDirected An acknowledgement from the EUM
that is correctly received by the CCU.
409,730
B rxPktsHCRCFail Packet received from an EUM, with a
corrupted header.
Note: This statistic also includes
random access packets that have
been received with corrupted headers.
2,464
C rxPktsFCS Fail Packet received from an EUM, with a
corrupted payload.
192
D replyOrRssiTimeouts No reply.
Note: This statistic also includes EUM
receive errors, by virtue of the fact that
if an EUM does not receive a poll from
the CCU, for any reason, then it will
not reply to the CCU.
22,688