Ring Simulation

• Signal Coupling and Simulation Feedback

  Amplifier placement may be required due to fiber and (R)OADM losses. To assess the WDM system performance, we can use the signal metric maps displayed for a particular transmission line (Figure 1) and a system performance summary table, as shown in Figure 2. In this particular design, no compensation of accumulated chromatic dispersion is required due to short optical channel routes and wide operating ranges of the selected transceivers.
  
  Closed optical paths may exist in complex mesh networks or simple rings, as shown in Figure 3. To prevent simulation feedback caused by such paths and to calculate signal metrics, VPIlinkConfigurator engine makes the network topology graph acyclic and computes the signals iteratively until a steady state is reached, as shown in Figure 4 and Figure 5.

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• Iterative Simulation and Target Power mode

  Design refinement typically starts at a point with no channels passing through, e.g. at a terminal node. However, in ring or mesh networks with closed optical paths, inserting an amplifier or attenuator causes changes of a signal at the points configured previously, e.g. an equalization of power levels of added and express channels in one link changes the power levels in a link configured at a previous step, as shown in Figure 6 and Figure 7. In other words, equipment readjustment is required at the points configured earlier.
  
  The Target Power mode fixes power levels at the points where closed optical paths are broken, and switches off iterations. Setting a particular power level as an initial guess at the ring break points simplifies the design refinement process and prevents iterative reconfiguration steps (Figure 8). See the next section for more information about manual link loss compensation.

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• Further Information

  Keywords: Ring Topology Design, Closed Optical Path, Simulation Feedback, Target Power, Iterative Simulation, Optical Power Equalization, Amplifier and DCM Placement, DWDM Mesh Network
  
  See also the WDM Network Design application example for more information about link loss and accumulated chromatic dispersion compensation.

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