## 4 Finite State Automaton in ER-ID
### State Transition Diagram  
The conditions that determine the identification of drones are complex and include subregions, multi-RF-CSs, battery energy, response time of detecting RF signals, availability of RF communications signal, possible local country aviation authority regulations, ADS-B readings from other aircrafts and other drones, and local restrictions on flights due to events, geofencing, and local airports. Satellite communications and GNSS readings for GPS are also involved. The electronic ID is a solution for RF communications and a method of identifying a drone to local aviation authorities, allowing them to send their electronic ID and receive information and possible commands from the local aviation authority. As GNSS is used for GPS or Glonass to pinpoint an object in space and time, it is not supported by our ER-ID RF communication solution. It is true that drones use GNSS to control their flight, and that modern drones use it to locate themselves, but this is not required because drones use gyroscopes in conjunction with control algorithms and PID controllers to position themselves in space and time. As a result, GNSS is important but not required for an object to fly from point A to point B, just as rockets and drones have gyroscopes to fly from point A to point B if GNSS is unavailable. As a result, in areas such as forests where GNSS, GPRS, IoT, and ADS-B are unavailable, we rely on satellites to transmit electronic IDs and gyroscopes to position ourselves in space and time. Thus, it is impossible to find the exact mathematical expression of the ER-ID process. In turn, control techniques that depend on the mathematical equations cannot be implemented to control this kind of operation. The FSA technique is applied to control real systems dependent on knowing only the Boolean logic conditions that realize the output of the system. In this section, the state transmission diagram is developed to identify the technique that will be used in this study to ER-ID of drones. Two elements are applied which are a circle and an arc. The circle, i.e. the state, represents the available RF-CSs in the path of the drone, while the arc represents the transition from one state to another when the Boolean algebra explained in Section 4.2 is achieved. The diagram of the transition is depicted in Figure 3. Figure 3 explains the details of the developed state machine of 8 states. The following state abbreviations are considered: A, IoT, B, W, 4G, S, and 5G denote ADS-B, IoT, Bluetooth, Wi-Fi, 4G, satellite, and 5G, respectively. Additionally, the abbreviations T and F are used to represent true and false conditions, respectively. In this way, B-T and B-F means Bluetooth signal is \"available\" and \"not available\", respectively. According to the designed state machine of Figure 3, the drone flies from Region 1 where satellite, 4G, and Bluetooth are available, to Region 2 where only satellite and Wi-Fi are available. In the first region, the drone ER-ID will be connected to state 4: Bluetooth. Hence, the consumed energy will be only 56.7 mW instead of 258.1 mW or 283.1 mW if it was connected to 4G or satellite, respectively. When the  
Figure 2: ER-ID control system.  
drone enters the second region, since the Bluetooth signal is False, the state is transmitted as state 1: Off. Then, it will go to state 5 to be connected with Wi-Fi.