7a. This time the first PSC performs simple power splitting, and assuming a
broadband splitter operation, each output port of the PSC will have all the downstream
channels, ?»1 ??¦ ?»n, which are then subject to the AWG operation, performing wavelength
routing from a single input port into n output ports. As such, each AWG output port
features a single wavelength from the ?»1 ??¦ ?»n range. With this configuration, each ONU
connected to a given AWG belongs to a completely different collision domain (PON
instance). This solution has one important advantage: it is more dynamic in the sense
that the ONUs in a given area might be assigned to various collision domains, depending
on their traffic demand. Unfortunately, such assignment needs to be performed
by a qualified technician and requires replacement of the ONU??™s hardware since the
Figure 7.7 Possible tree-and-branch architectures for WDM PON networks
AWG
Feeder section Stage 1 Stage 2 Drop section
Feeder section Stage 1 Stage 2 Drop section
Feeder section Stage 1 Stage 2 Drop section
PSC
OLT
ONU
?»1 ... ?»n
?»1 ... ?»n
?»1
?»n
PSC
PSC
OLT
ONU
?»1 ... ?»n
?»1 ... ?»n
?»1 .
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