Adaptive Redundancy CRDSA in UAV-LEO Satellite Covert Communication Networks

With the rapid development of integrated air-space-ground networks, ensuring secure and covert access for unmanned aerial vehicles (UAVs) to low Earth orbit (LEO) satellite constellations has become a critical challenge. This paper proposes the novel adaptive redundancy contention resolution diversity slotted ALOHA (AR-CRDSA) scheme to provide reliable and covert communication for UAV users. The core of the scheme involves a dynamic pairing strategy that conceals a low-power covert user (CU) transmission under the signal of a high-power legitimate user (LU), thereby shielding it from detection by adversarial reconnaissance satellites. A key innovation is the departure from transmitting identical packet replicas; instead, the AR-CRDSA protocol sends two distinct yet complementary packet versions to adapt to fluctuating channel conditions. This adaptive mechanism, combined with multi-satellite selection diversity and an iterative interference cancellation process, is shown through extensive simulations to significantly enhance the effective covert throughput and overall system reliability when compared to traditional random access protocols.