Jul 2026· 2026 6th International Conference on Intelligent Communications and Computing (ICICC)· pp. 1-6· 0 citations· 14 references
Abstract
As the role of satellites in sixth generation mobile communications system becomes increasingly well defined, satellite-terrestrial communications face an urgent need to improve spectral efficiency while ensuring user fairness. In this paper, we propose a multiple transmissive reconfigurable intelligent surfaces (RISs)-aided satellite-terrestrial downlink transmission scheme with rate-splitting multiple access. Based on statistical channel state information, we formulate a max-min user ergodic rate problem by jointly optimizing the satellite precoding, the phase shifts of multiple RISs, and the common-rate allocation. To tackle the resulting non-convex problem, we derive approximate closed-form expressions of multi-user ergodic rates and equivalently reformulate the problem via fractional programming. We then design a block coordinate descent-based algorithm to solve the transformed problem. Simulation results verify that the designed transmission scheme achieves significant performance gains in improving minimum user ergodic rate.
This work investigates a hybrid satellite-cell-free Massive MIMO system, where multiple low-Earth-orbit (LEO) satellites jointly serve users in unison with terrestrial access points (APs) under realistic imperfect channel state information and practical user association constraints.
Thu Tran Anh Ngo, Lo-Hai Long, Le Duc Anh Vu et al.· IEEE Transactions on Communi...· 1 citation
High-capacity satellite network is the cornerstone of future space-air-ground integrated networks. However, the satellite uplink transmissions still face critical challenges, including severe path loss, complex multi-user interference, and payload constraints. Recently, Reconfigurable Intelligent Surfaces (RIS) and Fluid Antenna Systems (FAS) have shown promise for satellite communications through their dynamic signal reconfiguration. This paper proposes a multi-RIS-assisted satellite Compact Ultra-Massive Antenna Array (CUMA) architecture for multi-user satellite uplink transmission. Specifically, we deploy multiple RISs on the terrestrial side to separate interfering Line-of-Sight (LoS) channels via optimized phase shifts, and adopt a CUMA receiver on the satellite to further mitigate interference through FAS port selection. To solve a sum-rate maximization problem, we alternately optimize FAS port selection using a Forward-Backward Greedy Selection (FBGS) algorithm and RIS phase shifts based on Fractional Programming (FP). To the best of our knowledge, this is the first work to jointly optimize multi-RIS and CUMA in a satellite uplink context, where strong LoS and extreme path loss fundamentally distinguish the design from terrestrial counterparts. Simulation results confirm the effectiveness of the proposed architecture across frequency bands. At 6 GHz, our scheme achieves 181% and 32% rate gains over fixed antennas and traditional CUMA schemes, respectively, while the gains also reach 138% and 27% at 26 GHz, illustrating superiority in both interference-limited and noise-limited regimes.
Kai Feng, Runke Fan, Tianheng Xu et al.· IEEE Open Journal of the Com...· 0 citations
In this paper, we propose an fluid antenna (FA)-enhanced interference exploitation symbol-level precoding (SLP) for downlink multi-user multiple-input single-output (MU-MISO) systems, focusing on transmitter-side fluid antenna systems (Tx-FAS) that allow flexible spatial correlation effects while preserving user portability. First, we derive an explicit expression for the achievable rate of SLP under finite-alphabet inputs, and further establish a closed-form upper bound that quantifies the theoretical rate improvement achieved by spatial reconfigurability of Tx-FAS. Subsequently, a joint optimization problem involving SLP design and Tx-FAS port selection is formulated to maximize the minimum user signal-to-interference-plus-noise ratio (SINR) under strict transmit power constraints. Due to the highly non-convex nature of the problem, we devise a genetic algorithm (GA) to efficiently obtain a near-optimal solution. Moreover, based on the optimal channel structure of SLP, we further develop a low-complexity algorithm with a spatial filtering mechanism to obtain a sub-optimal solution to the considered problem. Simulation results confirm that the proposed FAS-enhanced SLP scheme delivers notable performance improvements over both conventional precoding techniques and the FAS-only transmission approach.
Guorui Wei, Ang Li, Xiao-Yan Hu et al.· IEEE Transactions on Communi...· 0 citations
This paper investigates the performance of a satellite-terrestrial communication system employing rate-splitting multiple access (RSMA) to accommodate multiple users. The study focuses on assessing the system’s ergodic sum rate and symbol error rate (SER) under shadowed-Rician fading conditions. By deriving closed-form expressions, we analyze the influence of various power allocation strategies on overall system performance. The results, substantiated by numerical simulations, demonstrate that RSMA yields significant improvements over conventional non-orthogonal multiple access (NOMA) with respect to spectral efficiency and interference management. These findings offer valuable insights for the development of more reliable and efficient satellite-terrestrial networks.
Hong-Nhu Nguyen, Quang-Sang Nguyen, T. N. Nguyen· PLoS ONE· 0 citations
Integrated Sensing and Communication (ISAC) is emerging as a key technology for next-generation wireless networks, enabling simultaneous communication and sensing functionalities. This paper focuses a RIS-assisted full-duplex (FD) ISAC system, in which a multi-antenna base station (BS) concurrently performs multi-user uplink and downlink transmission while also carrying out radar sensing. To maximize the joint uplink–downlink sum rate, an optimization problem is formulated under practical constraints, such as radar detection SINR, self-interference, BS transmit power, user power budgets, and RIS unit-modulus conditions. To address the nonconvexity of this problem, a two-stage hybrid optimization approach is developed. In the first stage, the augmented Lagrangian technique decomposes the complex problem into simpler subproblems involving beamforming, power allocation, and RIS phase optimization, leading to a feasible initial solution. The second stage employs a Multi-Agent Deep Deterministic Policy Gradient (MADDPG) framework to refine this solution adaptively, enabling the system to respond effectively to variations in the channel environment, mobility patterns, and interference levels. The proposed hybrid framework achieves optimal resource allocation while maintaining feasibility, robustness, and adaptability. Analytical results confirm its convergence behavior, and extensive simulation results confirm that the proposed scheme consistently outperforms conventional optimization and single-agent DRL baselines in sum-rate maximization, interference mitigation, and sensing accuracy, confirming its effectiveness for RIS-assisted full-duplex ISAC systems.
S. Waqas, Fenghua Huang, Fakhar Abbas et al.· IEEE Transactions on Wireles...· 0 citations
Comparative analyses against ablation experiment frameworks and multiple access benchmark frameworks demonstrate that the proposed joint resource allocation distributed rate-splitting multiple access framework can improve the performance of low Earth orbit satellite communication systems while satisfying multiple constraint conditions.
Xianpeng Wang, Xi Han, Mingqi Gao et al.· IEEE Access· 0 citations
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