RIS-Empowered Secured Space-Air-Ground Integrated Networks: Opportunities and Challenges

The advent of 6G networks necessitates innovative solutions to address the limitations of traditional terrestrial wireless communications, particularly in remote and challenging terrains. The space-airground integrated network (SAGIN) combining satellite, aerial, and terrestrial segments, is a promising architecture to provide seamless, high-speed, and reliable connectivity. However, ensuring secure communication across these heterogeneous layers remains a challenge. This article explores the integration of reconfigurable intelligent surfaces (RISs) in SAGIN, presenting a comprehensive strategy to enhance physical layer security (PLS) across the network. The article first analyzes existing PLS challenges in SAGIN and explores how RISs integration and enabling technologies can address these security concerns. A practical case study demonstrates the application of RISs in the aerial layer to enhance SAGIN security. The findings demonstrate RISs' potential to mitigate eavesdropping risks, ensuring reliable communication systems. Finally, the article identifies open research directions and challenges for future investigations.