User's Manual Part 2

APCD-LM043-8.0 (DRAFT C) 165
11 Monitoring the Network
Although there are a large number of detailed statistics available for the various data handling
applications in the CCU (refer to Appendix J on page 277 for a complete list), there are only a
few that are key for monitoring system performance on an on-going basis. These statistics are
described in detail on the following pages.
•
CCU Transmit Statistics on page 165
•
CCU Receive Statistics on page 169
•
EUM Transmit Statistics on page 171
•
EUM Receive Statistics on page 172
•
User Data on page 173
•
Logging CCU or EUM Statistics on page 173
•
CCU Air Table Statistics on page 174
•
CCU Radio Meter on page 175
11.1 CCU Transmit Statistics
As described in CCU–EUM Interface MAC Layer (Polling MAC) on page 40, the MAC
continuously transmits polls to the EUMs. These polls can contain specific user payloads
directed to the EUM or the PC connected to the EUM, control payloads directed to the EUM,
broadcast payloads directed to all EUMs, or empty polls, which contain no payload.
In an ideal system, all data transmitted would be received error free by the EUMs, and no re-
transmissions would be required. In the real world, unfortunately, RF noise, low signal
conditions, interferers, system engineering problems, and equipment malfunction can result in
the need to retransmit data over the radio link. These retransmissions, which are key to
maintaining data integrity for the end user, come with the trade-off of reduced network
capacity.