Localization and Tracking in mmWave Radio Networks using Beam-Based DoD Measurements

3D-beamforming capabilities of multiantenna equipments in fifth generation (5G) networks, operating in the millimeter wave (mmW) band, allow for accurate positioning and tracking of users. In this paper, we propose a method for 3D positioning and tracking of moving user equipments (UEs) in 5G mmW networks based on downlink (DL) reference signals (RSs) and maximum ratio combining of subcarriers. In particular, we consider a system in which base stations (BSs) transmit beamformed DL RSs in a periodic manner and UEs exploit such RSs for estimating the BS-UE beam-pair gains by coherently combining all of the available subcarriers. This is achieved by a novel maximum likelihood (ML) estimator for the beam-pair gain. These beam-pair gain estimates are then reported back to the BSs, where they are used to estimate the direction of departure (DoD) of the DL RSs by a novel extended Kalman filter (EKF). The obtained DoD estimates from all available BSs are fused into a UE position estimate in a central unit of the considered network by a second stage EKF. Hence, the computational burden is distributed among different network entities. The proposed positioning algorithm may be implemented with minor modifications to the signalling scheme currently specified for the first phase (Rel. 15) of 3GPP 5G New Radio (NR) system. The performance of this positioning scheme is evaluated in a realistic ray-tracing based outdoor scenario resembling an automated truck platooning in a cargo port setting.