# A Review of Counter-UAS Technologies for Cooperative Defensive Teams of Drones
## 5 Command and Control Systems
Generally speaking, planning is the reasoning side of acting and is an abstract and explicit deliberation process that chooses and organizes actions by assessing the current environment's situation (i.e., through automated situational awareness) and by anticipating the expected outcomes of the planned actions. This deliberation aims to achieve some predefined objectives as best as possible. It has to be implemented according to the principles of automated planning, which is an area of artificial intelligence (AI) that studies this deliberation process from a computational point of view [105]. The addressed planning problem includes aspects of different planning cases, such as activity planning (which is concerned with the allocation of activities or targets to a given entity), route planning (which is concerned with the synthesis of routes from a starting position to a set of targets a in a given area of interest), perception planning (which is concerned with the planning around sensing actions for gathering information), communication planning (which is concerned with the planning of communication actions for the cooperation between different entities, both human and artificial), etc. All these planning cases may be combined in the mission planning case, which is related to the planning of actions or tasks by projecting the results of those actions according to a model of the involved entities and by evaluating the desirability of those results. In the specific case of an unmanned system (UMS) and of a network of unmanned systems (NUMS), mission planning is defined as the process for the synthesis of a sequence of tasks in terms of tactical objectives, a route (general or specific), timing and coordination actions [106]. According to these definitions, mission planning mainly refers to a strategic horizon, since it represents a decision-making process to set objectives and tasks and to compute high-level steps (e.g., routes, sensing actions, communication actions, etc.) to satisfy the assigned objectives and tasks. Thus, it usually covers a wide temporal and spatial range with respect to the missions. The outcomes of the mission planning process have to be provided to tactical planners (e.g., the autopilots of the single vehicles), which have to compute short-term and short-range actions (e.g., the real trajectories) to satisfy the assigned tasks. In the reference CUS, the C2 system has to optimize the operations carried out by the CUS and solve the mission planning process by:  
* Computing the set of tasks to be carried out to counter the identified threat;
* Processing the optimal schedule (i.e., assignment and ordering) of the tasks, e.g., the allocation and the sequencing of the target areas to be protected and of the vehicle counter activities (in terms of detection, identification, classification, tracking and neutralization) to be executed;
* Operating over the entire time horizon and space horizon of the threat resolution. Thus, it is a strategic planning level that sets the general objectives (the threat resolution strategy) and articulates the high-level steps to achieve them. Moreover, the reference mission planning is a dynamic (i.e., online) mission planning to face the dynamic threat scenario of the drone attack. Generally speaking, it is possible to carry out, where necessary or convenient, the following hierarchical decomposition for the C2 system: a module of the system may be explicitly in charge of the coordination of the team by means of a defensive team planning. Such a module is fed by the mission goals and the data of the team and deliberates the defensive tasks for all the vehicles by evaluating their effectiveness from the point of view of the team's mission and by considering the team's relationships and possible conflicts. It could be integrated in all the drones in order to obtain a decentralized architecture, in a single drone (working as team leader) or a in ground platform in the case of a centralized architecture.