# Review and Simulation of Counter-UAS Sensors for Unmanned Traffic Management
###### Abstract  
Noncollaborative surveillance of airborne UAS (Unmanned Aerial System) is a key enabler to the safe integration of UAS within a UTM (Unmanned Traffic Management) ecosystem. Thus, a wide variety of new sensors (known as Counter-UAS sensors) are being developed to provide real-time UAS tracking, ranging from radar, RF analysis and image-based detection to even sound-based sensors. This paper aims to discuss the current state-of-the art technology in this wide variety of sensors (both academically and commercially) and to propose a set of simulation models for them. Thus, the review is focused on identifying the key parameters and processes that allow modeling their performance and operation, which reflect the variety of measurement processes. The resulting simulation models are designed to help evaluate how sensors' performances affect UTM systems, and specifically the implications in their tracking and tactical services (i.e., tactical conflicts with uncontrolled drones). The simulation models cover probabilistic detection (i.e., false alarms and probability of detection) and measurement errors, considering equipment installation (i.e., monostatic vs. multistatic configurations, passive sensing, etc.). The models were integrated in a UTM simulation platform and simulation results are included in the paper for active radars, passive radars, and acoustic sensors.  
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In this contribution, we go a little further in the analysis of these technologies. In addition to describing some of the most interesting literature proposals and commercial products in the state of the art, we define a collection of simulation models, usable for some of those technologies and expandable to others, to be potentially usable for:  
1. Comparative assessment of potential systems deployment in a given position.
2. Analysis of integrated sensing solutions/data fusion approaches for C-UAS.
3. Analysis through simulation of the potential integration of the measurements from those sensors in UTM tactical chains, specifically to test the associated implications in their tracking and tactical services.  
In any case, the paper focuses on modeling the sensing processes for the different technologies, which would be a prerequisite for any of the previously described analyses. Finally, there are plenty of models of radar, RF, vision, and acoustic sensors. Here, we try to select, parameterize, and summarize those of real application for the detection of small drones in civilian applications (for UTM).  
The paper is structured as follows: In the second section of this paper, we describe in detail some of these sensing technologies, covering both the academic literature in the area and the fast-evolving commercial scenario. Meanwhile, the third section is devoted to deriving the simulation models of some of these sensors. This simulation models are to be incorporated in the UTM simulator described in [3]. The fourth section summarizes simulation results for some of the previous sensors, enabling a comparison of their main sensing features and performances, and finally, Section 5 concludes the paper, providing some insights on future work.