## 6 Conclusions  
We investigated the compensation of the distorted WDM signal through the MSSI-based DM link configured with the randomly distributed RDPS in the former half link. The RDPS arrangement in the latter half was classified into the cases of following or reversing the random distribution arrangement of those in the former half (random-follow or random-inverse), and the case of random with a different pattern irrespective of the arrangement in the former half section (all-random).  
It was confirmed that the compensation effect of the distorted WDM channel was improved overall in the link to which the dispersion map made of random-inverse distribution was applied, among the three cases. This result seems to be because the random-inversedistribution can establish a more symmetrical distribution map with respect to the midway OPC. In addition, it was confirmed that the dispersion maps generated by the random-inverse distribution are much more advantageous than the other two distributions for the flexibility of the dispersion-managed link design.  
The intention of this paper is to provide engineers with a flexible dispersion map configuration without the limitation of RDPS arrangement in designing a dispersion-managed link with the midway OPC, and to provide a sufficient and selectable design margin at these links. The random distribution of the RDPSs proposed in this study, especially the random-inverse distribution, and the NRD margin and power margin in this configuration can be seen as the result that can sufficiently satisfy the purpose of our study compared to the existing links such as the conventional DM link.  
However, it requires a lot of effort to randomly arrange the RDPS of the fiber spans consisting of the former half link so that acceptable compensation quality can be derived, and even if such a random pattern is found, another complication may be that the RDPS arrangement in the latter half link has to be reversed to that of the former half.  
Nevertheless, we think that the method of randomly distributing the RDPS of the fiber spans of the former half link and artificially constructing the RDPS distribution in the latter half can be considered a new approach to flexibly configuring the dispersion-managed link and increasing the compensation effect at the same time.  
Furthermore, as we specified the shape of the dispersion map based on random-inverse distribution that can further improve the compensation performance, it is expected that this work can practically contribute to design and setup of the MSSI-based DM link with the detailed arrangement guidance and the system margin of random RDPS induced in this study.  
Conceptualization, J.-P.C. and S.-R.L.; methodology, S.-R.L.; software, S.-R.L.; analysis, J.-P.C. and S.-R.L.; resources, S.-R.L.; data curation, S.-R.L.; writing--original draft preparation, J.-P.C. and S.-R.L.; writing--review and editing, J.-P.C. and S.-R.L.; visualization, S.-R.L.; super-vision, J.-P.C. and S.-R.L.; project administration, S.-R.L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to institutional regulations.  
The authors declare no conflict of interest regarding the publication of this paper.