Radar Altimeter Coexist Design in the 4.2-4.4 GHz Band for Multi-Stage Interference Risk Mitigation in 5G and Beyond

This paper addresses safety concerns in aviation arising from the 5G network's interference with radar altimeters on 14 CFR Pt 25 category aircraft, predominantly used in passenger travel. Radar altimeters, crucial for critical flight phases and conditions like reduced visibility and collision avoidance, face accuracy threats due to 5G's overlapping frequency range. The study explores a strategic approach to mitigate potential airborne interference between radar altimeters and 5G signals, particularly considering the emerging Space Air Ground Integrated Network (SAIGN). It proposes a redesign of the existing radar altimeter system and analyzes the certification process for such changes, focusing on the Technical Standard Order (TSO) perspective. The research adheres to the Federal Aviation Administration's (FAA) Project Specific Certification Plan, ensuring compliance through Change Impact Analysis, Means of Compliance, and Test Plans. The study's findings aim to ensure operational integrity in an increasingly interconnected airspace, addressing both current and future challenges posed by advanced communication networks.