Satellite networks are emerging as core infrastructure for sixth-generation (6G) wireless systems, yet they face stringent constraints on bandwidth, onboard energy, processing capability, and link availability that bit-oriented communication cannot resolve. Semantic communication, which extracts and transmits task-relevant meaning rather than raw bits, offers a principled remedy across the satellite stack. This survey provides a layered overview of satellite semantic communication, covering: (i) the physical layer with channel-aware joint source-channel coding (JSCC) under long propagation delay, severe Doppler, and time-varying signal-to-noise ratio (SNR); (ii) onboard semantic processing with lightweight encoders, model compression, and in-orbit edge inference for radiation-hardened payloads; (iii) inter-satellite link (ISL) and network-layer routing, distributed federated learning across constellations, and 3rd Generation Partnership Project (3GPP) non-terrestrial network (NTN) integration; and (iv) representative applications spanning Earth observation (EO), satellite Internet of Things (IoT), direct-to-device (D2D), and deep-space scenarios. We synthesize quantitative gains across orbital regimes, identify open challenges in security, standardization, and heterogeneous-orbit interoperability, and outline directions including foundation-model compression, neuromorphic onboard computing, and carbon-aware orchestration for sustainable space connectivity.
Tung Son Do, Thanh Phung Truong, The-Vi Nguyen et al.· International Conference on...· 0 citations
Open Radio Access Network (O-RAN) enables flexible and intelligent radio access network operation through disaggregation, virtualization, open interfaces, and RAN Intelligent Controllers (RICs). At the same time, the data required to train artificial intelligence and machine learning models in O-RAN is naturally distributed across user equipment, base stations, edge clouds, and management entities, which makes centralized learning costly and privacy-sensitive. Federated Learning (FL) has therefore emerged as a promising paradigm for O-RAN intelligence because it enables distributed model training without transferring raw data. In this work, we survey recent studies on the fusion of FL and O-RAN and classify them into three categories: 1) FL-assisted network control, where FL is used as a collaborative learning tool for slicing, offloading, routing, and security; 2) FL training-efficiency optimization, where communication cost, learning latency, resource consumption, and convergence are improved under O-RAN constraints; and 3) integrated approaches that jointly consider network performance and FL efficiency. Based on this taxonomy, we discuss open research challenges, including device heterogeneity, mobility, RIC integration, communication-efficient learning, and security threats, such as model poisoning and inference attacks.
Junsuk Oh, Donghyun Lee, Chunghyun Lee et al.· International Conference on...· 0 citations
Unmanned aerial vehicle (UAV) communications are a promising enabler for 6G networks, offering flexible deployment and strong line-of-sight channel conditions. Effective UAV operation requires jointly optimizing trajectory and user scheduling to balance throughput and information freshness. This paper proposes a proximal policy optimization (PPO)-based deep reinforcement learning (DRL) framework that controls UAV movement and user scheduling together via a joint MultiDiscrete action space. We formulate a Markov decision process for a 8-user, $1000 \times 1000 \mathrm{~m}^{2}$ service area with a 3GPP TR 36.777-compliant channel model, where the agent selects both its next position and which user to serve at each time slot. The proposed PPO policy achieves 85.75 Mbps mean throughput, a 24.4% improvement over the AoI-greedy baseline, while reducing mean AoI by 87.7% compared to the throughput-greedy baseline, reaching a Pareto-optimal trade-off between the two competing objectives. An ablation study over the AoI penalty weight confirms a clear throughput-AoI trade-off, validating the joint design.
Quang Tuan Do, Tung Son Do, Thanh Phung Truong et al.· International Conference on...· 0 citations