Performance Evaluation of Fingerprint-Based Indoor Positioning Using RSSI in 802.11ah

In incineration plants, indoor positioning systems are needed to prevent workers from approaching hazardous areas and to facilitate rescue operations in emergencies. Although many positioning systems using signal strength indicators such as Wi-Fi Received Signal Strength Indicator (RSSI) have been proposed, the vast interior of incineration plants increases the cost of constructing a communication infrastructure using $\mathbf{5 G H z}$ Wi-Fi. Therefore, by adopting Low Power Wide Area (LPWA), which allows for long-distance communication, the number of Access points (APs) that need to be installed in the environment can be reduced, thus lowering the cost of constructing the communication infrastructure. IEEE 802.11ah (11ah) is a new LPWA standard that uses the Sub-GHz band. In this study, we deployed new 11ah receivers in an incineration plant where IEEE 802.11ac (11ac) is already established and evaluated their coverage and area classification performance. The experiment demonstrated that the entire incineration plant can be covered with fewer units compared to 11ac. Additionally, when a small number of 11 ah receivers were installed, the system identified individual rooms with higher accuracy than 11ac, suggesting that 11ah RSSI is a promising feature that can be obtained at low cost.