Nfb-Dub Mode; Figure 2-13 Mrb-Dub Frame Of A 3 Carrier Network; Figure 2-14 Nfb-Dub Frame - ND SatCom SKYWAN IDU 7000 Manual

General Carrier Design
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Essential SkyWAN Satellite Link Layer Features
A graphical representation of a 3 carrier MRB-DUB network is given in figure 2-13. For both
MRB modes, the master stations must be able to receive their own bursts on carrier 1.
Figure 2-13 MRB-DUB Frame of a 3 Carrier Network

NFB-DUB Mode

This is the only mode where the master station does not need to receive its own reference
burst. There is only one downlink population for all slave stations. The single reference burst
is transmitted on carrier 3. Two uplink populations are possible, uplink population 1 uses carrier
1 and uplink population 2 carrier 2 for ranging and request bursts. If only one uplink population
exists in the network, carrier 2 will not be defined. The following restrictions apply:
- Only one master station is possible, no backup master functionality.
- Pure star topology with the master station serving as a hub. No satellite link between
slave stations.
- If two uplink populations are used, carrier 1 and 2 must have the same symbol rate,
modulation and coding.
A graphical representation of the frame structure of an NFB-DUB network with one uplink pop-
ulation is given in figure 2-14. Note that in contrast to the MRB modes there is no time slot
boundary alignment between carrier 1 (or 2) and carrier 3. This is not required here, because
channel 3 is only used by the single master station which does not need to coordinate its trans-
mission times with any other station in the network.
Figure 2-14 NFB-DUB Frame
32 Network Design and Engineering Guide 2010-10-26