I. Introduction
5G and Beyond 5G communication systems are expected to play an important role in intelligent transportation [1], complementing on-board sensors such as radar, lidar, and global navigation satellite system (GNSS), by providing an absolute position estimate, even in harsh urban and indoor environments. To realize 5G/B5G positioning, standardization efforts in 3GPP and ETSI as well as different means of technical enhancements are provided to support a variety of commercial use cases with different performance requirements [2], [3]. The main technical enabler for accurate positioning in 5G vehicular networks is the ability to operate at mmWave frequencies above 24 GHz, which brings a number of concrete benefits [4], [5], [6]: (i) Large bandwidths in the order of 400 MHz are available at mmWave, providing high delay resolution; (ii) A greater number of antenna elements can be deployed within a fixed footprint in mmWave compared to sub-6 GHz, both at BS and UE sides. This allows for high angular resolution and the potential for UE orientation estimation; (iii) Due to increased shadowing and less reflection, the propagation channel at mmWave tends to be more geometric compared to sub-6 GHz carriers, enabling the development of practical and scalable model-based positioning algorithms.