  The automotive and railway industries are rapidly transforming with a strong
drive towards automation and digitalization, with the goal of increased
convenience, safety, efficiency, and sustainability. Since assisted and fully
automated automotive and train transport services increasingly rely on
vehicle-to-everything communications, and high-accuracy real-time positioning,
it is necessary to continuously maintain high-accuracy localization, even in
occlusion scenes such as tunnels, urban canyons, or areas covered by dense
foliage. In this paper, we review the 5G positioning framework of the 3rd
Generation Partnership Project in terms of methods and architecture and propose
enhancements to meet the stringent requirements imposed by the transport
industry. In particular, we highlight the benefit of fusing cellular and sensor
measurements and discuss required architecture and protocol support for
achieving this at the network side. We also propose a positioning framework to
fuse cellular network measurements with measurements by onboard sensors. We
illustrate the viability of the proposed fusion-based positioning approach
using a numerical example.
