Toward ۶G: Artificial Intelligent, Advanced Radio Access Networks, and Emerging Wireless Technologies

The sixth-generation (۶G) wireless networks represent a transformative leap beyond ۵G, promising unprecedented data rates up to one terabit per second, ultra-low latency, massive connectivity, and enhanced reliability to support emerging applications such as holographic communications, brain-computer interfaces, and pervasive AI-driven services. This paper presents a comprehensive survey of ۶G key technologies, including terahertz communications, ultra-massive MIMO, reconfigurable intelligent surfaces, integrated sensing and communication, and advanced AI/ML integration. We explore the evolution of intelligent Radio Access Networks (RANs) toward cloud-native, open, and AI-driven architectures that enable dynamic resource management and autonomous operation. Furthermore, we analyze the critical challenges in embedding AI into ۶G networks, such as data quality, model complexity, security risks, and the need for seamless orchestration across heterogeneous domains. Our study highlights the pivotal role of AI in realizing the vision of ۶G and outlines open research issues essential for the development of ultra-dense, energy-efficient, and intelligent wireless networks.