# Communication Infrastructure Design for Reliable UAV Operations in Air Mobility Corridors
## 4 Discussion
### Resource-Reliability Trade-Off for UAV Communication Strategies
Strategy 2 demonstrates reduced sensitivity \(S_{\lambda}^{2}=-0.87\), showing the stabilizing effect of dual redundancy. Strategy 3 achieves balanced sensitivity across all parameters \(S_{\lambda}^{3}=-0.45,\;\;S_{\mu}^{3}=0.31,\;S_{\rho}^{3}=-0.28\), suggesting robust performance under parameter variations. Strategy 4 exhibits the lowest failure rate sensitivity of \(S_{\lambda}^{4}=-0.12\), but it offers only marginal improvements over Strategy 3. Redundancy optimization involves balancing multiple competing objectives: maximizing availability, minimizing infrastructure costs, and maintaining operational efficiency. A multi-objective optimization framework is formulated as follows:  
_Minimize_\(f_{1}(N)=-A(N)\): maximize availability. _Minimize_\(f_{2}(N)=-C(N)\): minimize cost. _Minimize_\(f_{3}(N)=\rho_{critical}(N)\): maximize performance margin. These are subject to the following:  
\[A(N)\geq A_{min},\quad C(N)\leq C_{max} \tag{16}\]  
where \(N\) is the redundancy configuration vector (e.g., number of stations or level of overlap), \(A(N)\) is system availability, \(C(N)\) is the total infrastructure cost, \(\rho_{critical}(N)\) is the traffic intensity at which availability drops below the required threshold, and \(A_{min}\) and \(C_{max}\) are availability and cost constraints, respectively. Pareto frontier analysis (Figure 24) reveals that Strategy 3 consistently lies on the efficient frontier across a wide range of cost-availability trade-off scenarios. For availability requirements between 99.5% and 99.9%, Strategy 3 provides the best cost-effectiveness. Strategy 4 becomes optimal only when availability requirements exceed 99.95% or when traffic intensity \(\rho>0.8\). Strategy 2 represents a compromise for moderate reliability demands (95-99%) under strict budget constraints. Figure 23: Sensitivity analysis for redundancy level optimization. This comprehensive sensitivity analysis framework empowers system designers to make informed decisions about redundancy configurations, based on specific operational goals, infrastructure budgets, and uncertainty margins--ultimately achieving an optimal balance between reliability and resource efficiency throughout the system lifecycle. Step-by-Step Procedure for Designing Communication Infrastructure for Reliable UAV Operations in Air Corridors  
The design of a robust communication infrastructure is a critical enabler for safe and efficient UAV operations in UAV corridors. This section outlines a step-by-step methodology developed in this study for the selection, placement, and reliability assessment of radio repeater stations within structured air corridors. The methodology supports both linear and non-linear corridor geometries and is adaptable to different operational and environmental conditions. Step 1. Corridor definition and segmentation. The first step involves defining the overall geometry and extent of the UAV corridor. In realistic urban environments, corridors often follow segmented or broken-line paths due to terrain, airspace restrictions, or infrastructure layouts. Therefore, the total corridor length, \(D\), is divided into smaller segments, \(D_{i}\), such that  
\[D=\sum_{i=1}^{z}D_{i} \tag{17}\]  
Each segment, \(D_{i}\), is treated independently in the subsequent design process, allowing for differentiated strategies, depending on the segment's characteristics, such as UAV traffic density, risk level, or physical constraints. Step 2. Assign repeater stations to corridor nodes. All directional changes, bends, or nodes along the UAV corridor must first be identified, as these points are critical for maintaining reliable communication and navigational clarity. At each of these nodes, at least one radio repeater station should be installed to ensure uninterrupted signal coverage and seamless transitions between corridor segments.