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Considering the metro network, where each
Figure 3: Unamplified filterless solution with
frequency reuse for the horseshoe topology.
C O M PA R A T I V E A N A LY S I S O F
HARDWARE COST AND POWER
CONSUMPTION
An analysis regarding the number of
components involved in the metro horseshoe
network solutions using the L-band (amplified
and unamplified FD&W) is performed.
As already pointed out, the difference
between the amplified and unamplified
solutions only regards the existence of
amplifiers inside the L-band architecture node.
For L-band solutions, we consider two hub
nodes with CD ROADM R&S architecture,
similarly to the C-band, and nine tributary dual-
band nodes, as illustrated in Figure 1, with
FD&W ChD architecture in the L-band. The
tributary node architecture considers the
FD&W ChD solution and the transmission of 70
channels in the L-band per fiber. The number of
required transponders in each L-band node is
28.
Thus, besides considering two C/L filters to
separate/aggregate the two bands and two
amplifiers per node, each tributary FD&W ChD
node has four S/C 1:2, four S/C 1:16 (two per
add and two per drop structure). The hub node
architecture for the L-band is based on a 5-
degree CD ROADM R&S architecture.
hub node is connected to 3 different hub nodes
and two tributary nodes, for an A/D ratio of
20%, a total of 112 wavelengths must be
added/dropped per A/D structure in each hub
node. As WSSs with a maximum dimension of
1:20 are considered in the A/D structure, it is
necessary to use 6 A/D cards to achieve this
total of added/dropped wavelengths (which
means we have a total of 12 WSSs 1:20 in the
A/D structure).
Table 1 shows the L-band's power
consumption and capacity per node and the
total cost and power consumption for the
entire horseshoe network. The total capacity
per fiber reaching the tributary node and hub
node in the L-band is, respectively, 7 Tbps and
28 Tbps, determined from the number of WDM
channels and the transponder capacity, which
is, respectively, 70 channels and 100 Gbps for
the tributary node and, respectively, 140
channels and 200 Gbps between hub nodes.
The total capacity per node, also shown in
Table 1, is achieved by calculating the capacity
per A/D structure. So, the capacity per tributary
node is 2.8 Tbps, and the average total
capacity per hub node is calculated
considering that 2/5 of the transponders of the
hub node are working at 100 Gbps and the
other 3/5 are at 200 Gbps, leading to a total
capacity per hub node is 17.9 Tbps.
Table 1: Hardware count, cost and power consumption of
each optical component existing in the nodes tributary
and hub in the L-band. The total cost of the hub and
tributary nodes are shown at the bottom of the table.
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