On the Limitations of Ray-Tracing for Learning-Based RF Tasks in Urban Environments
Abstract
We study the realism of Sionna v1.0.2 ray-tracing for outdoor cellular links in central Rome. We use a real measurement set of 1,664 user-equipments (UEs) and six nominal base-station (BS) sites. Using these fixed positions we systematically vary the main simulation parameters, including path depth, diffuse/specular/refraction flags, carrier frequency, as well as antenna's properties like its altitude, radiation pattern, and orientation. Simulator fidelity is scored for each base station via Spearman correlation between measured and simulated powers, and by a fingerprint-based k-nearest-neighbor localization algorithm using RSSI-based fingerprints. Across all experiments, solver hyper-parameters are having immaterial effect on the chosen metrics. On the contrary, antenna locations and orientations prove decisive. By simple greedy optimization we improve the Spearman correlation by 5% to 130% for various base stations, while kNN-based localization error using only simulated data as reference points is decreased by one-third on real-world samples, while staying twice higher than the error with purely real data. Precise geometry and credible antenna models are therefore necessary but not sufficient; faithfully capturing the residual urban noise remains an open challenge for transferable, high-fidelity outdoor RF simulation.
Cite
@article{arxiv.2507.19653,
title = {On the Limitations of Ray-Tracing for Learning-Based RF Tasks in Urban Environments},
author = {Armen Manukyan and Hrant Khachatrian and Edvard Ghukasyan and Theofanis P. Raptis},
journal= {arXiv preprint arXiv:2507.19653},
year = {2025}
}
Comments
This work has been submitted to the IEEE for possible publication. This work was supported by funding under the bilateral agreement between CNR (Italy) and HESC MESCS RA (Armenia) as part of the DeepRF project for the 2025-2026 biennium, and by the HESC MESCS RA grant No. 22rl-052 (DISTAL)