## 3 Network of Mobile Sensory Units
### Mobile (Portable) Sensory Units  
Basic units, and mobile sensory units will be implemented in the form of separate free-standing units and portable devices as needed. The devices will have separate hardware equipment, which distribution in space creates a sensory network. Our work aims to model the formation of such a network.  
The mobile sensory unit is a modular element of a transportable monitoring system with clear diversity of used sensors. The electrical independence of the system is provided by suitable batteries. Depending on the solar activity the batteries will be charged up by photovoltaic panels, to extend the period of operation of the monitoring system. The mobile sensory units are equipped with a control module to provide collection and preliminary data processing from individual sensors to make ensure autonomous operations.  
The mobile sensory unit is designed for continuous monitoring of the surrounding area to inform about possible unauthorized entry into the area of interest or about leaving the monitored area. The obtained data During the monitoring of the area of interest are processed, evaluated and transmitted by the communication module using the low-energy LoRa communication network. The data is sent from the mobile sensory unit to the central sensor station where it is recorded to a storage medium and data backup is realized by forwarding them from the mobile monitoring station to the data server.  
Although the mobile sensory unit is fully autonomous during normal operations, its activity can be partially controlled by an operator from a mobile monitoring station. The unit can be placed single, in a group, or combined manner, which defines the perimeter of the area of interest. It is possible to create a sensory communication network with the help of several mobile sensory units. In this case, the task could be to monitor whether there has been a violation of the defined area. All sensory units communicate and are controlled by the central sensor station. This means that in the communication concept, individual sensory units are involved in a communication star topology with a central control unit. Incase of malfunction of this central station, it is possible to replace it with another suitable unit. If it is impossible to find this central station, the units can communicate with their neighboring units in an emergency communication topology circle and thus forward important data further. The number and location of these free-standing units are directly dependent on the topography of the country. Depending on the sensor units used, it is necessary to evaluate the appropriate placement according to distance and direct visibility between these free-standing column-shaped units, with a separate power source and a separate set of sensors. Each portable sensor unit has a function of its localization using the global navigation satellite system (GNSS). Here arises the importance of how to deploy individual sensor units in the field so that they can cover the protected perimeter with their range and at the same time be within communication range with the central unit too. It is essential to find an algorithm or method for the automated design of the optimal placement of sensory units in the target area.  
One of the other requirements for the features of the scheme was the possibility of displaying the location of the object on the virtual map of the terrain and its 3D display for the needs of the operator. It is ideal to use a digital terrain model (DTM) as background material for the target area, which comprehensively describes the shape of the land surface with elevations. It is also possible to directly insert a vector layer of objects into the given model to display the digital model of the relief. To display these objects in 3D form, it is necessary to list their heights above the ground in the attribute table.