# Deployment Protection for Interference of 5G Base Stations with Aeronautical Radio Altimeters
## 1 Introduction
[18] examined the transmitting power of 5G base stations and its impact on fixed-satellite services, utilizing a C-band receiver antenna. Ref. [19] employed unmanned aerial vehicles (UAVs) to measure the interference caused by 5G base stations, presenting a more comprehensive interference picture than conventional methods. Ref. [20] used Monte Carlo methods and minimum coupling loss to calculate the protection distance of 5G networks from FSS. Ref. [21] focused on the issue of 5G interference in future Non-Terrestrial Networks (NTNs). They proposed two mathematical frameworks to address the problems of inter-beam and inter-satellite interference in satellite 5G beam systems. Refs. [22; 23] conducted a study on the interference generated by a Wireless Avionics Intra-Communications (WAIC) system utilizing 5G technology. However, these studies have not fully resolved the issue of interference with radio altimeters in aviation. The main problems are described as follows. 1. They have not yet proposed an integrated interference model tailored to the complex operational scenarios of aircraft, nor have they provided a method for calculating protective measures in accordance with aviation safety requirements. 2. They have not adequately explored the variations of protection zones under dynamic aircraft operational scenarios, nor have they proposed deployment protection measures for dynamic situations. Moreover, their discussion of path loss is overly simplistic. 3. They have failed to provide an effective and direct analytical framework for addressing the deployment of 5G base stations near airports and to offer direct mitigation measures for base station deployment. To address these challenges, we approach the problem from the perspective of aviation operational safety. Direct recommendations can be provided for the establishment of prohibited zones and the implementation of interference mitigation measures for base station deployments near airports. The main differences between this study and previous work are summarized in Table 1. The primary contributions of this work are described as follows. Figure 3: Interference scenarios. First, we propose a novel deployment protection method to define prohibited zones, considering aviation safety requirements such as the WCLS (Worst-Case Landing Scenario) and ICAO 6 dB margin, and conduct analysis for both horizontal and vertical prohibited zones. The adoption of an integrated computational model addresses issues where other analytical models are not applicable to civil aviation operations. 2. Second, we investigate the variations of prohibited zones during aircraft dynamic operations, considering factors such as an aircraft's roll/pitch angle, altitude AGL, and the stochastic feature of path loss. We examine three different base stations (rural macrocells (RMas), urban macrocells (UMas), and urban microcells (UMis)), two antenna configurations (an omnidirectional antenna and 16 \(\times\) 16 beamforming antenna arrays), and the deployment height and vertical scan angle of the base station. 3. Finally, we discuss methods for mitigating interference within the prohibited zones using beamforming technology, employing power control and angle shutoff techniques to protect radio altimeters. This provides a new approach for deploying 5G base stations near airports while ensuring aviation safety.