Ray-traced digital twin improves 5G positioning accuracy and testing
A Ray-Traced Digital Twin for 5G NR Positioning with OpenAirInterface
Information Theory
Summary
Measuring 5G positioning in the real world is hard because each test only reflects one place and setup. The authors created a detailed virtual copy of a 5G test site that runs the same software but uses simulated signals based on a 3D model. This digital twin keeps the timing details needed for accurate location measurements and matches the real system’s meter-level precision. Using the twin, they found that increasing the signal bandwidth helps reduce some errors but not height errors, which are mainly limited by how the antennas are arranged. They showed that placing antennas at different heights can greatly improve vertical accuracy.
What this means in practice
- •For telecom network operators: Simulate and evaluate alternative 5G antenna layouts and positioning scenarios without new physical field tests using a realistic digital twin.
- •For industrial automation teams: Design 5G positioning setups with variant antenna heights to improve vertical location accuracy in complex indoor or outdoor environments.
Authors
Nima Chaharbaghi, Florian Kaltenberger, Bartosz Podrygajlo, Rakesh Mundlamuri, Roberto Verdone
Abstract
Evaluating 5G positioning on a physical testbed ties every measurement to one propagation environment and one antenna layout, so any question about an alternative deployment requires a new field campaign. We present a ray-traced digital twin of the GEO-5G testbed at EURECOM that drives an unmodified OpenAirInterface (OAI) 5G stack with per-antenna channels computed by Sionna-RT over a 3D model of the site. The distributed gNB antennas are modelled as independent radio devices rather than as elements of a compact array, which preserves the per-antenna absolute delays on which time-difference-of-arrival (TDoA) positioning depends. With them preserved, the twin drives OAI's SRS-based UL-TDoA pipeline to metre-level accuracy consistent with that reported for the physical deployment. We then use the twin to answer a question the physical testbed cannot. Widening the carrier truncates the tail of the horizontal error distribution without improving a typical position, and leaves the vertical error untouched, because the latter is limited by the array geometry rather than by the measurement. That limit is predictable from the antenna coordinates alone, and a height-diverse layout reduces the RMS height error by a factor of four.