Age of Information Optimization in Energy-Harvesting Systems with Intermittent Markovian Connectivity

Real-time communication systems increasingly operate over ephemeral channels whose quality or availability degrades over time. Examples include satellite communication links, where loss of line-of-sight intermittently disrupts connectivity, and quantum communication channels, where quantum state fidelity decays due to noise and decoherence. In such scenarios, maintaining timely and reliable information delivery becomes a critical challenge. Age of Information (AoI) has emerged as a key performance metric for quantifying information freshness in real-time systems, capturing the time elapsed since the generation of the most recently received update. Unlike traditional latency metrics, AoI directly reflects the relevance of delivered information to time-sensitive applications. This thesis investigates the interplay between AoI and ephemeral communication channels, focusing on how temporal degradation of the channel impacts the delivery of fresh information. We review existing AoI frameworks and analyze their applicability to communication environments characterized by intermittent availability and time-varying reliability. Particular attention is devoted to the tension between stringent timing requirements and the transient nature of these channels. By synthesizing insights from satellite and quantum communication contexts, this thesis highlights fundamental trade-offs and identifies open challenges for designing efficient status-update systems over ephemeral communication links.