“…Over time, different aspects of the protocol have been analyzed (e.g., throughput [11,12], energy consumption [13], delay performance for connection-oriented applications [14], neighbor discovery process [15], channel utilization and the adaptive frequency hopping scheme [16]), including BLE suitability for IIoT applications [17][18][19] and proposed solutions to meet the real-time demands set for IIoT [19,20]. For example, in [17], the reliability of BLE for industrial wireless sensor and actuator networks is evaluated by studying a point-to-point link based on the physical layers 1M and 2M of BLE under different wireless channels, while in [18] the potential of BLE for industrial automation is explored by testing the hardware in metal enclosure with different antennas and varying transmitting power. In [19], the suitability of BLE for time-critical IIoT applications is evaluated showing that by optimally modifying the BLE retransmission scheme, it is possible to ensure reliability and timeliness requirements of IIoT applications, while in [20] the real-time communication problem is solved for Bluetooth mesh networks by proposing a multi-hop real-time BLE protocol, which is developed on top of BLE to obtain bounded packet delays over mesh networks.…”