**5. Conclusions**

Using a local-scale model and real world example, we experimented with optimal scheduling of multiple radars for multiple targets and derived appropriate results. Simulation results show that the objective function of the proposed formulation is valid and effective for the real world situation by using target handover. The experiment results show that the proposed exact algorithm solved using Gurobi exhibited better results than that of the heuristic method in terms of performance, number of handovers and tracking load for entire systems. This paper opens the possibility of solving the problem of seamless multi-target tracking of multiple radar network against a large number of missile attacks. The results are especially helpful in preventing situations in which radars with limited detection area are unnecessarily tracking multiple targets at the same time. The resulting margin of tracking capability will increase the survivability in such situations. For future work, first, we will try to find adaptive parameters that may not be confined to a specific situation for each coefficient of objectives constituting the objective function. Second, we will expand and connect this sensor assignment problem into the weapon target assignment problem for an anti-air defense system which is composed of multiple radars and multiple interceptor systems. Third, we will continue to study the methodology to apply the Reinforcement Learning (RL) technique to this problem.

**Author Contributions:** Conceptualization, J.K., D.-H.C., W.-C.L., S.-S.P. and H.-L.C.; methodology, D.-H.C. and J.K.; software, D.-H.C., J.K., W.L. and S.-S.P.; validation, J.K. and D.-H.C.; formal analysis, J.K.; resources, D.-H.C.; data curation, J.K.; writing—original draft preparation, J.K. and D.-H.C.; writing—review and editing, J.K. and H.-L.C.; visualization, J.K. and D.-H.C.; and supervision, project administration, and funding acquisition, H.-L.C. **Funding:** This work was conducted at the High-Speed Vehicle Research Center of KAIST with the support of the Defense Acquisition Program Administration and the Agency for Defense Development under contract UD170018CD. The first author is supported by the scholarship program of the Republic of Korea Navy.

**Acknowledgments:** The authors would like to thank the Editor and the anonymous reviewers for their valuable comments and suggestions.

**Conflicts of Interest:** The authors declare no conflict of interest.
