Fluid, movable, and AI-enabled adaptive antenna technologies for 6G: evolution, unified taxonomy, challenges, and research directions

초록

The rapid evolution of sixth-generation (6G) wireless networks demands antenna systems capable of adapting to highly dynamic communication environments characterized by user mobility, severe signal blockage, complex propagation conditions, and increasingly heterogeneous service requirements. Conventional fixed antenna architectures are unable to provide the flexibility, spatial adaptability, and intelligence required to support these emerging scenarios. Consequently, adaptive antenna technologies (AATs), including reconfigurable antennas, beam-steerable antennas, fluid antenna systems, movable and rotatable antennas, and artificial intelligence (AI)-enabled adaptive antennas, have attracted significant research attention. Unlike existing surveys that primarily focus on individual AATs, this review presents a unified framework that integrates electromagnetic reconfiguration, spatial mobility, and AI-native intelligence within a single multidimensional taxonomy. The proposed taxonomy systematically classifies AATs according to hardware architecture, reconfiguration mechanism, intelligence level, and spatial adaptability, while providing a comprehensive comparative analysis of their operating principles, enabling technologies, advantages, limitations, and representative applications. Furthermore, the review examines key implementation challenges associated with energy efficiency, security and privacy, terahertz (THz) communications, standardization, interoperability, and compatibility with existing fifth-generation (5G) infrastructure, together with a phased deployment roadmap toward practical AI-native 6G networks. Emerging research directions, including AI-native antenna ecosystems, digital twin-assisted optimization, reconfigurable intelligent surface-integrated adaptive antennas, semantic-aware communications, integrated sensing and communication, and spatial intelligence networks, are also discussed. The findings demonstrate that the future evolution of AATs will rely on the synergistic integration of advanced electromagnetic design, spatial reconfiguration, and AI-driven optimization, providing a comprehensive reference and practical roadmap for researchers and engineers developing intelligent, autonomous, and sustainable 6G wireless communication systems.

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