Utility-Critical Prompt Transmission Scheme for Dual-Hop Lunar Farside Explorations

The prompt transmission scheme initials the status generation and updates to the destination according to its requests, offering reductions in unnecessary transmissions for satellite with limited resources, which has the potential to save energy while keeping freshness in lunar farside explorations. In this article, we propose a semantic-empowered metric termed utility loss of information (UoI) for lunar farside explorations, where a lunar rover can be modeled as a multistate Markov source. The proposed UoI captures the freshness and usefulness of information, as well as the synchronization of transceivers and energy consumption, to simultaneously quantify the AoI, value loss of information, mismatch of transceiver, and energy cost of transmission. By designing the single satellite relay and dual-satellite coordinative modes in Lunar farside explorations, a UoI-critical prompt (UP) transmission scheme is proposed for the lunar rover generates status and update to the Earth control center. Moreover, we propose a reliability-enhanced UP (Re-UP) scheme to further improve the average UoI (AUoI) over long distance and time-varying fading channel, which can realize the synchronization of transceivers with at most one-time long erasure coding retransmission. The upper and lower bounds of AUoI in UP and Re-UP schemes are derived. Simulation results indicate that our Re-UP scheme can achieve the optimal tradeoff among freshness, usefulness, synchronization of transceivers, and energy cost in both modes, and the dual-satellite coordinative mode can further improve the freshness and usefulness of information.