WaveRider LMS4000, User Manual

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13 Specialized Applications
156 APCD-LM043-4.0
In this EUM thin-route case, the traffic on the radio channel “b” network traverses two airlinks
— the first from the users’ EUMs to the CCU on radio channel “b”, then the second from the
thin-route EUM to the CCU on radio channel “a”. This situation reduces the available
throughput of the CCU on radio channel “a” by the amount of the traffic on the radio channel
“b” network. Depending on the number of EUMs in the radio channel “b” network and their
subscribed grades of service, the thin-route EUM may need to be assigned a special grade of
service, which can be obtained from WaveRider.
13.2 EUM Backhaul
In some cases, it may be cost-effective to use an EUM as the backhaul link as an alternative to
a separate wired or wireless link to the CCU, as is illustrated in
Figure 50 .
Figure 50 Using an EUM for Backhaul
In the EUM backhaul case, nearly all traffic traverses two airlinks — the first from the users’
EUMs to the CCU then the second from the CCU to the backhaul EUM. This situation reduces
the available throughput of the CCU by half. To ensure that the backhaul EUM gets half the
polls and that no packets are dropped in the transmit queues, a special GOS class definition
still need to be used for the backhaul EUM, and for no others. This special GOS class is
available, as an option, from WaveRider.
Backhaul EUM3000
CCU3000
Antenna
EUM3000
EUM3000
Data path from end-user
modem to network