A comprehensive survey on 6G: Enabling technologies, key applications, and future challenges

The rapid evolution of wireless communication technologies from 1G to 5G has enabled remarkable advances in connectivity, yet emerging applications such as holographic telepresence, autonomous systems, wireless brain–computer interfaces, and ubiquitous 3D coverage expose fundamental limitations in current networks. While numerous surveys have explored individual 6G enablers, few studies provide a unified and comprehensive analysis that integrates the technological foundations, architectural transformations, and multidisciplinary applications required to realize future 6G systems. This manuscript addresses this gap by offering a holistic overview of 6G, beginning with the motivation for moving beyond 5G and the performance demands driving next-generation research. It synthesizes key enabling technologies including terahertz communication, ultra-massive MIMO, intelligent reflective surfaces, AI-native networking, Digital Twin Networks, and generative artificial intelligence. The paper further examines new architectural models spanning terrestrial, aerial, satellite, and underwater networks, while also discussing emerging 6G use cases across healthcare, robotics, industry, mobility, and immersive environments. Finally, the manuscript outlines open challenges and research directions that must be addressed to transform the 6G vision into practical reality. By bridging foundational concepts and forward-looking innovations, this survey provides a comprehensive reference for researchers and practitioners seeking to understand and contribute to the evolving 6G landscape.