A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks

Abstract

The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is mainly driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely lowlatency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks, which are expected to bring transformative changes to this premise. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. In particular, the present paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a comprehensive study of the 6G vision and outlining seven of its disruptive technologies, i.e., mmWave communications, terahertz communications, optical wireless communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss the associated requirements, key challenges, and open research problems. These discussions are thereafter used to open up the horizon for future research directions. INDEX TERMS 6G, backscatter communications, drone-based communications, terahertz communications, metasurfaces, mmWave, optical wireless communications, tactile internet.

Large Intelligent Surface-Assisted Nonorthogonal Multiple Access for 6G Networks: Performance Analysis

“…However, this comes at the expense of reduced energy efficiency, which constitutes a fundamental challenge in the 5G and beyond wireless networks [9]. Large intelligent surface (LIS) has recently emerged as a disruptive energy and spectrally efficient technology, which is capable of offering a programmable control over the wireless environment [10], [11]. This can be realized by incorporating reflective elements (REs) which manipulate the impinging electromagnetic waves to perform various functionalities, such as wave reflection, refraction, absorption, steering, focusing and polarization [12].…”

The Road Towards 6G: A Comprehensive Survey

“…[33] Oct. MIMO An overview of holographic MIMO surface (HMIMOS) communications including the available hardware architectures for re-configuring such surfaces, highlighting the opportunities and key challenges in designing HMIMOS-enabled wireless communications for 6G. [34] Oct. Survey A comprehensive study of 6G visions, requirements, challenges, and open research issues, outlining seven disruptive technologies, i.e., millimeter wave (mmWave) communications, THz communications, optical wireless communications, programmable meta-surfaces, drone-based communications, back-scatter communications, and Tactile Internet. [35] Nov. THz Analyzes link budget of THz links with justified estimates of calculus terms, such as the achievable or required noise figure, transmit power, and antenna gain.…”

“…The authors of [33] provided an overview of holographic MIMO surface communications as a promising technological enabler for 6G wireless communications. Recently, Bariah et al gave a comprehensive 6G vision in [34], identifying seven disruptive technologies, associated requirements, challenges, and open research issues. From the viewpoints of radio frequency (RF) hardware and antenna, [35] analyzes link budget of THz communication links with justified estimates of calculus terms, such as the achievable or required noise figure, transmit power, and antenna gain.…”

6G Ecosystem: Current Status and Future Perspective

“…A study says the human body may attenuate the signal by 20-35 dB [9]. Another challenge will be at high frequencies design and fabrication of transceivers for mobile devices is extremely complicated [127]. Besides, the power required to handle the high frequency processing such as Analog to Digital Conversion (ADC) for sampling is yet to be known [28,132].…”

“…Incorporating this challenge as a part of 6G network with different frequencies to communicate for underwater (low frequency) and terrestrial will meet the key requirement of the future networks. The acoustic communication mainly spans between acoustic waves, RF, and optical wireless frequencies; a thorough channel modeling for all three cases is an intricate task [127,9].…”