“…In contrast to outdoor positioning, where the majority of systems and applications rely on GNSS, many technologies have emerged to provide positioning indoors. They are based on: Wireless Communication Technologies (Wi-Fi [ 5 , 19 , 20 ], BLE [ 18 , 21 ], RFID [ 22 , 23 ], FM [ 24 ], Ultra Wide Band [ 18 , 25 , 26 ]), Ultrasounds [ 27 , 28 ], IMU’s [ 13 , 29 , 30 , 31 ]; signals of opportunity [ 32 ], Optical and Vision [ 11 ], visible light [ 4 ], and Magnetic, [ 33 ] among others. Selecting the right technology might not be an easy task since many features have to be balanced, such as target application, deployment costs, required accuracy, tolerable uncertainty or needed computational resources.…”