# Radio Frequency Interference, Its Mitigation and Its Implications for the Civil Aviation Industry
## 3 Literature Review
The study identifies the main challenge to determining the necessary restrictions on 5G base station emissions to protect radio altimeter functionality. The findings indicate that unwanted 5G emissions must be 35 dB more stringent than the current 3 GPP standards to prevent interference with altimeters. Figure 2 shows the interference scenario in the above-discussed paper, while Figure 3 shows the analysis method. [PERSON] et al. [18] conducted a study on identifying sources of civil aviation radio interference using four UAVs. It highlights the limitations of traditional ground-based monitoring methods, which are often slow and ineffective in tracking aerial interference. The study aims to develop an innovative time-frequency difference positioning method to improve monitoring accuracy and efficiency. The research successfully establishes a synchronized model for UAVs and demonstrates its effectiveness through simulations, achieving balanced positioning performance and minimal errors across various deployment configurations. The findings underscore the method's potential for practical applications in aviation safety. Figure 2: An interference scenario by [PERSON] [17]. Schematic representation of the radio altimeter beam spread over a hexagonally divided ground surface, illustrating signal coverage at two different aircraft altitudes. The blue cones indicate the area covered by the altimeter signal, which expands as the altitude increases. In this figure, H represents the altitude of the aircraft above ground level, while D denotes the diameter of the corresponding radio altimeter footprint on the ground. The terms \(H_{landing}\) point and \(D_{landing}\) point refer to the aircraft’s altitude and signal footprint, respectively, at the moment of landing. [PERSON], [PERSON], and [PERSON] [19] examine how RFI influences the electromagnetic emissions of ICs used in automotive applications. The primary objective is to elucidate how RFI can compromise the functionality and adherence of ICs to EMC standards. The intended readership comprises IC manufacturers and automotive suppliers, particularly those involved in safety-critical applications. A significant challenge addressed is the sequential nature of EMC testing, which frequently overlooks the interplay between electromagnetic immunity and emissions. The results indicate substantial increases in electromagnetic emissions due to injected disturbance signals, resulting in the functional degradation of ICs. Consequently, the findings emphasize the necessity of integrated testing approaches to ensure both safety and regulatory compliance in automotive electronics. Figure 4 provides an example of EMI emissions, while Figure 5 shows the architecture of EMI emissions used by [PERSON], [PERSON], and [PERSON] [19]. [PERSON] [20] presents a detailed view and explores the critical role of electrical and electronic technology in the twenty-first century, alongside the escalating issue of EMI resulting from the widespread use of electronic devices. It clarifies the often-confused terms EMI and EMC, providing their precise definitions and detailing their interrelationship. The paper underscores that EMI is a disturbance that causes malfunctions or undesired responses in electronic systems, whereas EMC denotes the ability of equipment to operate as intended within its electromagnetic environment. Additionally, it examines the assessment of EMI/EMC and strategies for mitigating EMI issues, with a particular focus on the significance of PCB design in addressing these challenges. For interference mitigation this paper emphasizes implementing bonding, grounding, shielding, and filtering procedures  
Figure 4: Example of EMI emissions in study by [PERSON], [PERSON], and [PERSON] [19]. Figure 3: The analysis method used by [PERSON] [6]. regularly to address EMI and achieve EMC. It also highlights the significance of best PCB design, the proper construction of structural systems, and addressing communication and radar systems for EMC in naval ships and marine platforms.