# Revolution or Evolution? Technical Requirements and Considerations towards 6G Mobile Communications
## 1 Introduction  
The rapid growth of smart emerging technologies and their features (e.g., real-time, interactive services) have contributed to the significant increase in wireless data traffic that cannot be fully supported sufficiently by the current network, even with fifth generation (5G) systems [1]. That indicates that the available deployed mobile networks will not be able to fully and efficiently keep up with the changing technical standards. Furthermore, a more developed digital society that is driven by nearly instantaneous and limitless wireless connectivity by 2030 is projected [2]. This has propelled the development of sixth generation (6G) to meet high technical standards of new spectrum- and energy-efficient transmission methods [1, 3]. The 6G mobile networks are expected to support a highly dense network connecting 500 billion machines [4]. Its capacity can go up to 1000 times higher than the capacity of 5G. Through the 6G mobile network with a higher frequency spectrum, users can expect an even higher speed (where the data transfer rate is expected to be 100 to 1000 times higher than what 5G offers), enhanced capacity, and even lower latency that can support the prospects of new applications, including precision medicine, intelligence disaster prediction, and virtual reality (VR). In particular, 6G would offer data transfer rate in Gbps to Tbps through the utilization of multi-band high-spread spectrum that includes 1-3 GHz band, millimeter wave (mmWave) band (30-300 GHz), and terahertz (THz) band (0.06-10 THz) [5; 6]. Considering the development trend of earlier mobile networks, the initial 6G mobile network would adopt the current architecture and strengths of 5G, such as higher frequency bands and an optimized decentralized network system. Although 6G mobile technology will provide several advantages to future ultra-dense networks, there are several issues that will still need to be highlighted, discussed, and then addressed before the standardization of the 6G system. Therefore, conducting a survey paper that considers different aspects and discusses technical challenges from different perspectives will contribute to achieving these targets. In the literature, there are plenty of reputable 6G review journals and white papers that have been published. There are hundreds of survey papers related to 6G technology, but in this paper, only a few reputable articles are selected to be discussed and their limitations to be highlighted, as summarized in the following paragraphs. The research paper of [7], presents an extensive survey of the existing developments regarding 6G. In addition, it shows the societal and technological trends that are leading towards the 6G movement. After that, the latest applications that comprehend the demands caused by 6G driving trends are explained. In addition, it discusses the requirements needed to attain the 6G applications. The article then presents a detailed description of the critical enabling technologies and a brief overview of the existing research projects and activities, including standardization efforts towards 6G development. Finally, a summary of the lessons acquired from the latest research is presented, and the technical difficulties faced are elaborated, which would present the directions for future research in the field of 6G. A review study in [8] is also another extensive survey work conducted and focused on the evolution of wireless technology towards 6G networks. The focus is mainly on the latest architectural modifications related to 6G networks, defined by universal three-dimensional (3D) coverage, the inception of pervasive artificial intelligence (AI), and improved network protocol stack. In addition, the authors also discuss the relevant aspiring technologies that help create sustainable and socially impeccable networks, involving THz and visible light communication (VLC), blockchain, new communication paradigms, and symbiotic radio.