In the Spotlight of 5G User Plane Positioning: A Study of Indoor Scenarios on the Real-World Stage

The fast positioning of medical service robots in hospitals is a challenging task. Therefore, this paper presents a performance analysis around different LTE Positioning Protocol (LPP) transactions, which are performed over the user plane of a fifth generation (5G) network to transport position-related data. More precisely, the transaction time of the LPP capabilities and location information transactions is investigated depending on the number of additional technologies, such as Wi-Fi and Bluetooth, and the presence of a line of sight (LOS) connection to the serving 5G base station. For this purpose, a Lego Mindstorms EV3 robot, which is used with a Raspberry Pi Zero 2 W, a Quectel RM520N-GL 5G modem, an Archer T2U Nano Wi-Fi adapter and a BMP581 pressure sensor, is moving along three different real-world indoor scenarios: (i) The line of sight is always present, (ii) it is temporarily interrupted (N/LOS), and (iii) the line of sight is permanently broken (NLOS). The statistical results show that the number of used technologies influences the transaction time of LPP location information more than the corresponding LPP capabilities. If the Wi-Fi and Bluetooth technologies and a barometric pressure sensor are used together with 5G, the transaction time of LPP location information transfers increases by 2,521% (capabilities: 31.86%) in the LOS scenario compared to a 5G only case. In contrast, line of sight changes do not appear to have a clear negative impact on the transaction time of LPP capabilities and location information transfers, respectively.