COBHAM Sailor 250 FleetBroadband, Training Manual, Page: 32 / 270

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1
Chapter 1
Inmarsat Network
Figure 1-33: Forward direction connection bearers
Above fi gure illustrates how the resulting layout mechanism time-
slices capacity on the forward bearers for the various connections
active on each FleetBroadband Terminal.
The forward frame in the narrow beam has several FEC blocks and
each may have a different code rate. In the case of F80T4.5X8B
bearer there are 8 FEC blocks in each 80 msec. frame. The RNC
scheduler must decide what code rates each of the FEC blocks
must use by examining how much data each FleetBroadband
Terminal is to receive during the scheduling period and what their
current link conditions are.The fi rst FEC block includes broadcast
signalling so it must always be sent with a code rate low enough
for the least capable FleetBroadband Terminal.