5G Positioning with SDR-based Open-source Platforms: Where do We Stand?

While GPS has traditionally been the primary positioning technology, 3GPP has more recently begun to include positioning services as native, built-in features of future-generation cellular networks. With Release 16 of the 3GPP, finalized in 2021, a significant standardization effort has taken place for positioning in 5G networks, especially in terms of physical layer signals, measurements, schemes, and architecture to meet the requirements of a wide range of regulatory, commercial and industrial use cases. However, experimentally-driven research aiming to assess the real-world performance of 5G positioning is still lagging behind, root causes being i) the slow integration of positioning technologies in open-source 5G frameworks, ii) the complexity in setting up and properly configuring a 5G positioning testbed and iii) the cost of a multi-BS deployment. This paper sheds some light on all such aspects. After a brief overview of state of the art in 5G positioning and its support in open-source platforms based on software-defined radios, we provide advice on how to set-up positioning testbeds, and we demonstrate, via a set of real-world measurements, how to assess aspects such as reference signal configurations, localization algorithms, and network deployments, even with a cost-constrained limited-size testbed.