Toward 6G Evolution: Three Enhancements, Three Innovations, and Three Major Challenges

Over the past few decades, wireless communication has witnessed remarkable growth, experiencing several transformative changes. This article offers a comprehensive overview of wireless communication technologies, from the foundations to the recent wireless advances and future trends. Specifically, we take a neutral look at the state-of-the-art technologies for the fifth generation (5G) and ongoing evolutions towards 6G, while also reviewing the recommendations of the international mobile communication vision for 2030 (IMT-2030). We first highlight specific features of IMT 2030, including three IMT-2020 extensions and three new innovations—ubiquitous connectivity and integrating the new capabilities of sensing & artificial intelligence with communication functionality. Based on key findings, we delve into three major challenges in implementing 6G, along with global standardization efforts. Besides, a proof of concept is provided by demonstrating terahertz (THz) signal transmission using orbital angular momentum (OAM) multiplexing, which is one of the potential candidates for 6G and beyond. To inspire further potential research, we conclude by identifying research opportunities and future visions on IMT-2030 recommendations.