Doppler Radar Performance for UAV Speed Detection in mmWave/sub-THz Systems with Directional Antennas

Abstract

Unmanned Aerial Vehicles (UAVs) have become integral to a multitude of domains facilitating and sometimes even replacing human labor. Yet, the substantially increasing number of these aerial devices raises concerns regarding the elevated risk of collisions and accidents that could pose harm to humans. To guarantee safety and efficiency of UAV operations, UAVs should always have accurate and up-to-date information not only about their location but speed as well. Conventionally, traditional positioning infrastructures like Global Navigation Satellite Systems (GNSS) or base stations have been utilized for this purpose. However, a wide range of mission-critical applications often necessitate the deployment of UAVs in environments lacking conventional positioning infrastructure. In these scenarios, the reliable and real-time positioning of UAVs remains a serious challenge. One potential solution is the utilization of radar systems, which offer unique capabilities for UAV positioning without relying on external infrastructure. This paper explores the concept of employing Doppler radar technology for UAV localization, specifically focusing on its ability to scan the surrounding environment to detect the speeds of neighboring UAVs utilizing the Doppler effect. By leveraging the principles of stochastic geometry, we present a comprehensive analysis to determine the optimal beamwidth required to detect the speeds of all UAVs in the vicinity within minimal time. Our research indicates that a half-power beamwidth of up to 20∘ enables the differentiation of objects’ speed with a 95% probability, but this capability is effective only within a range of 50 m.