“…Roughly, those methods can be classified into two categories, namely, the received signal feature-based methods, and the propagation time-based methods [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38]. The received signal strength indicator (RSSI) fingerprint is the most widely adopted feature to indicate position information in favor of its simplicity and accessibility [15,16,17,18,19,20,21,22,23,24,25]. Generally, the fingerprint based schemes are conducted in two phases, i.e., an offline phase followed by an online phase.…”