Multi-Functional RIS-Aided Anti-Jamming Communication in Semantic Integrated Satellite-Ground Networks

Integrated satellite-ground network (ISGN) emerges as a promising key component of the sixth-generation (6G) wireless networks due to its potential capabilities in providing ubiquitous connectivity for global coverage and reliable services. However, the inevitable existences of high-volume data, uncontrollable propagation environment, and malicious jamming attacks pose three significant bottlenecks for enabling efficient ISGN. With these focuses, we propose a novel framework of multi-functional reconfigurable intelligent surface (MF-RIS) aided semantic anti-jamming communication in ISGN. Under this framework, a semantic transceiver exhibits inherent robustness and data compression capability, and MF-RIS can customize the full-space wireless environment by leveraging its signal reflection, refraction, amplification, and energy harvesting functions, thereby achieving substantial global coverage, reliable connectivity, and high-rate transmission. Based on our proposed framework, we formulate a total semantic rate maximization problem considering the impacts of jammer's channel state information (CSI) imperfection, while maintaining the semantic similarity requirement, semantic rate target, and MF-RIS's self-sustainability. Then, by transforming the imperfect CSI into a worst-case one by exploiting a discretization method, we propose a fast-converging monotonic optimization algorithm that is combined with decoupling second-order cone programming to obtain a globally optimal solution with fewer feasibility evaluations. Numerical simulations demonstrate the superiority of our proposed framework and algorithms compared to various benchmarks.