Information freshness under non-terrestrial connectivity

Information freshness is becoming increasingly critical with the proliferation of communication networks and portable communication devices. Non-terrestrial networks exhibit unique challenges arising from line-of-sight constraints, dynamic traffic conditions, and the diverse architectural components. These characteristics make them a compelling scenario for analyzing optimal configurations and energy consumption. In this work, we examine two different non-terrestrial communication models: a deterministic model with intermittent connectivity caused by periodic loss of line-of-sight and a multi-user multi-queue model in which traffic is split over multiple servers. For the intermittent connectivity model, we derive a closed-form expression for the metric known as Age of Information and demonstrate its linear dependence on the generation rate, service rate and duration of the active phase, as well as its inverse relationship with the duration of the inactive phase. We also introduce the concept of packet usefulness for the multi-user multi-queue scenario and derive a closed-form expression for the shared queue. Our results highlight the importance of traffic splitting in reducing both the Age of Information and the overall resource consumption.