OTFS-superimposed PRACH-aided Localization for UAV Safety Applications

TL;DR

This paper introduces a novel OTFS-modulated PRACH-based localization method for UAVs, improving accuracy in emergency scenarios by leveraging Doppler-tolerant signals and analyzing optimal UAV speeds.

Contribution

It pioneers a standards-compliant OTFS PRACH scheme for UAV localization, analyzing its performance and optimizing UAV speed for enhanced accuracy in emergency applications.

Findings

Achieves about 20% RMSE improvement in static conditions.

Up to 80% RMSE reduction in high-mobility scenarios.

Demonstrates the effectiveness of OTFS in UAV localization.

Abstract

The adoption of Unmanned Aerial Vehicles (UAVs) for public safety applications has skyrocketed in the last years. Leveraging on Physical Random Access Channel (PRACH) preambles, in this paper we pioneer a novel localization technique for UAVs equipped with cellular base stations used in emergency scenarios. We exploit the new concept of Orthogonal Time Frequency Space (OTFS) modulation (tolerant to channel Doppler spread caused by UAVs motion) to build a fully standards-compliant OTFS-modulated PRACH transmission and reception scheme able to perform time-of-arrival (ToA) measurements. First, we analyze such novel ToA ranging technique, both analytically and numerically, to accurately and iteratively derive the distance between localized users and the points traversed by the UAV along its trajectory. Then, we determine the optimal UAV speed as a trade-off between the accuracy of the ranging technique and the power needed by the UAV to reach and keep its speed during emergency operations. Finally, we demonstrate that our solution outperforms standard PRACH-based localization techniques in terms of Root Mean Square Error (RMSE) by about 20% in quasi-static conditions and up to 80% in high-mobility conditions.