## 4 An IoT-Based Real-Time Location Monitoring System by Using BLE
### Proposed System Architecture and Workflow  
To overcome these issues, our proposed technique uses BLE, which is a low-power and low-cost technology. This proposed methodology reduces the deployment cost and complexities by using the BSs of the existing cellular network infrastructure for the communication process. The system architecture of BLE-based real-time location monitoring in mines by using the IoT is shown in Figure 7. In this scenario, two base stations (BS) are deployed to provide necessary services (uplink/downlink) to the BLE devices through the central office server as shown in Figure 7a, and the complete workflow is shown in Figure 7b. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Technology** & **Advantages** & **Disadvantages** \\ \hline GPS & _Large coverage area_ & _Inefficient for underground_ \\  & & _mines_ \\ \hline GSM & _Large coverage area_ & _Communication delay exists_ \\ \hline RFID & _Non line-of-sight_ & _High maintenance of RFID tags,_ \\  & _Communication, High_ & _Low Security_ \\  & _Penetration, Compact Size_ & _High penetration loss/ Signal_ \\ \hline RF TECHNOLOGY & _Non line-of-sight_ & _High penetration loss/ Signal_ \\  & _Communication_ & _attenuation is very high_ \\ \hline RADAR & _Accurate and High Penetration_ & _High CapEx and OpEx_ \\ \hline ZIGBEE & _Low Power Consumption, Low_ & _Low Penetration, Poor_ \\  & _Latency Time, Cheap_ & _non-interference_ \\ \hline BLUETOOTH & _Low Power Consumption, Low_ & _High CapEx and OpEx, Small_ \\  & _Latency Time_ & _coverage area_ \\ \hline \hline \end{tabular}
\end{table} 
Table 6: A comparative analysis of some existing technologies. Figure 7a shows the coverage area of BLE and cell towers based on their transmitted power. The blue and green colored portion shows the energy region of BLE devices and cell towers, respectively. As can be seen, cell tower 0 transmits more power compared to cell tower 1. All the BLE devices are wearable or are attached to the employee working inside the mines. In this proposed method, beacons are considered because they can be easily identified by single board computers (SBC) as shown in Figure 8. Different beacons are accessed by the nearest SBC based on their coverage area. The blue-colored region indicates the transmitted energy by the beacon signal as shown in Figure 8a. The system contains beacons that are small and inexpensive, which emit signals in the same fashion as BLE. The used beacons have a short-range and can triangulate position in the same way that a phone uses cell towers with an assisted global positioning system (AGPS). These transmitters are deployed at known points inside the mines, and they permit the device to obtain area fixes. This data can be utilized to make new client encounters, for example, turn-by-divert headings for indoor situating from gateways/applications that read the guide signals. Figure 7: Proposed system architecture and workflow. (**a**) Proposed System Model; (**b**) Complete Workflow Process. The scenario presented in Figure 8a,b shows the position of the SBC (fixed position) and a random distribution of BLE devices, as the position of BLE device (wearable) depends on the position of the employee working inside the mine. The BLE receivers/gateway receives the universally unique identifier (UUID) transmitted by the beacons in a repetitive manner as shown in Figure 8a,b. These signals can be utilized to differentiate between subgroups and individual ones in the subgroups. It is modified to check the accessible BLE signals \"on the air\" and the received signals contain the accompanying snippets of data in a bundle size of 60 bits, with 10 bits specifying major and minor values. The received signal strength indicator (RSSI) values can be utilized to decide the distance of the receiver to every one of the reference points. As those region statistics are stored inside the database, navigation of the receiver also can be tracked, and alerts can be generated if certain rules are violated.