## 5 Summary and Consideration for Implementation of Optical Link  
In this section, we would like to summarize the simulation results and to mention the points to be considered, when implementing the results of this study into the SMF- and EDFA-based optical link. The dispersion map configurations in which the zero-crossing place of cumulative dispersion is not constant and the dispersion distribution profile is symmetrical around the midway-OPC is more effective in compensating the distorted WDM signal than the conventional dispersion map. The fact that the dispersion profile should be symmetric with respect to the midway-OPC means that the role of the OPC is important in compensating for the nonlinear distortion of the signal amplified by the EDFA, and the optimization of the dispersion map is also an important factor in signal compensation, taking into account the correlation with the OPC added to the link. The classification of the dispersion map proposed in this study is based on the shape of the dispersion profile of each FSG and the residual dispersion of each fiber span even if the zero-crossing place of the cumulative dispersion is the same. That is, even if the  
Figure 7: The product of available launch power and effective TRD for each rRD. zero-crossing place of the cumulative dispersion is the same, the dispersion map proposed in this study is classified into 16 types depending on the increase/decrease in the dispersion profile of each FSG, the variation rate of rRD for each FSG and the residual dispersion of each fiber span. Among the factors that specifically determine the shape of the dispersion map, it is found that the variation rate of rRD for each FSG had the greatest impact on compensation performance. It is confirmed that the dispersion map of the fixed configuration, in which the residual dispersion per each fiber span are equally allocated regardless of the number of fiber spans consisting of the FSG, is most advantageous for increasing the power margin of the WDM channel and securing the flexibility of dispersion-managed link design. For the rest three configurations considered in this paper, the residual dispersion per each fiber span assigned to fiber span of any FSG must be determined by artificially multiplying or dividing the rRD by the number of fiber spans consisting of the corresponding FSG. That is, the fixed configuration can design the dispersion-managed link relatively simply compared to other configurations. Next, by examining the effect of rRD of each fiber span on WDM channel compensation, it is confirmed that relatively excellent compensation is obtained when rRD was set to the value of around 400 ps/nm, irrelevant with the dispersion map configurations. Summarizing the results obtained through simulation in this paper, although the zero-crossing place of the cumulative dispersion is different, the compensation effect of WDM channel distortion by applying the dispersion map whose distribution is symmetric with respect to the midway-OPC can be more increased than the conventional dispersion map. In this case, the excellent compensation can be obtained by uniformly setting the residual dispersion in all fiber spans to around 400 ps/nm. Quantitatively, if the dispersion map of the fixed configuration with rRD of 400 ps/nm is applied to the link, depending on the specific location of the zero-crossing of the cumulative dispersion and the shape of the dispersion distribution of the FSG, the power margin can be more increased from 2 to 3 dB, and the product of available launch power and effective TRD can be increased by more than 200 dBm (ps/nm) compared to the conventional dispersion map. The dispersion maps dealt with in this study are artificial and special ones that are symmetric around the midway-OPC and the zero-crossing place of the cumulative dispersion is not constant. In other words, the process of designing the 16 dispersion maps shown in this paper can be cumbersome compared to the dispersion maps reported in other studies.