5GNR Indoor Positioning By Joint DL-TDoA and DL-AoD

Abstract

Positioning a user terminal based on cellular signals is an attractive solution in situations where accurate positioning based on global navigation satellite systems (GNSS) is not possible, such as inside buildings. The 5G New Radio (NR) networks based on 3GPP have introduced several enhanced features to allow the accurate positioning of user terminals. Especially Frequency Range 2 (FR2) mmWave setups are attractive for localization because the large bandwidths allow for high-resolution estimation of the Time Difference of Arrival (TDoA) while the beamforming capabilities can be exploited to estimate the Angle of Arrival (AoA) or Angle of Departure (AoD) of the signals.In this work, we propose a new UE-based positioning algorithm that combines the Downlink Time Difference of Arrival (DL-TDoA) and Downlink Angle of Departure (DL-AoD) information estimated from the downlink positioning reference signals (DL-PRS) introduced in 3GPP Rel-16. TDoA is a widely used horizontal positioning technique that does not require tight synchronization between base stations and mobile stations. Moreover, multiple antennas beamforming on base stations leads to high vertical positioning accuracy with AoD. We use ray-tracing-based site-specific channel models to evaluate our joint positioning algorithm’s performance in an Indoor Factory (InF) scenario. The simulation results show sub-meter user localization error which is a significant improvement compared to applying the previous methods separately.