  Indoor Positioning System (IPS) is a crucial technology that enables medical
staff and hospital managements to accurately locate and track persons or assets
inside the medical buildings. Among other technologies, Bluetooth Low Energy
(BLE) can be exploited for achieving an energy-efficient and low-cost solution.
This work presents the design and implementation of an received signal strength
indicator (RSSI)-based indoor localization system. The paper shows the
implementation of a low complex weighted k-Nearest Neighbors algorithm that
processes raw RSSI data from connection-less iBeacon's. The designed hardware
and firmware are implemented around the low-power and low-cost nRF52832 from
Nordic Semiconductor. Experimental evaluation with the real-time data
processing has been evaluated and presented in a 7.2 m by 7.2 m room with
furniture and 5 beacon nodes. The experimental results show an average error of
only 0.72 m in realistic conditions. Finally, the overall power consumption of
the fixed beacon with a periodic advertisement of 100 ms is only 50 uA at 3 V,
which leads to a long-lasting solution of over one year with a 500 mAh coin
battery.
