Non-orthogonal Multiple Access for 6G: Solutions, Challenges, Opportunities, and Future Research Trends

Dear Colleagues,

The rapid escalation of data-hungry applications and massive connectivity between accessible devices presents many challenges for the 6G networks. 6G has the potential to enable the betterment of the society by providing support in the realization of smart homes, smart cities, Industry 4.0, agriculture, health care systems, etc. However, all of this comes at the cost of extensive research and implementation challenges. Several technologies have been proposed to solve these problems, such as massive multiple input–multiple output (MIMO), millimeter wave (mmWave) communication, intelligent reflecting surfaces (IRSs), unmanned aerial vehicles (UAVs), cell-free networks, and multiple access (MA). Considering the requirements of massive connectivity with low latency and high throughput, MA is considered as one of the major pillars of 6G systems. Particularly, nonorthogonal multiple access (NOMA) is considered to be a potential solution towards achieving the goal of 6G. Many efforts have been put towards the analysis of different NOMA strategies, but still there is a need to address the signal processing problems related to transmission strategies and interference cancellation. This Special Issue aims to highlight the advances in strategies and signal processing in NOMA for future deployments of 6G.

This Special Issue aims to provide a forum for the presentation of original research and review articles to identify signal processing techniques and to explore the possible applications of NOMA to fulfill the goal of 6G wireless systems.

Potential topics include but are not limited to the following:

• Advancements in signal processing for MIMO/mmWave/IRS-NOMA systems for 6G system.
• Advancements in signal processing for cognitive-radio-inspired NOMA systems for 6G system.
• Channel estimation strategies for NOMA assisted networks for 6G system.
• PAPR reduction techniques for multicarrier NOMA for 6G system.
• Exploration and analysis of software defined NOMA for 6G system.
• Resource allocation in NOMA for 6G system.
• Exploration of NOMA in IoT, health care, device-to-device(D2D), UAV etc. applications.
• NOMA for simultaneous wireless information and power transfer (SWIPT)

• Analysis of NOMA with hardware impairment related to 6G system.
• Role of soft computing and edge computing in NOMA for 6G system.
• Prototype development for 6G system.
• Application specific case studies related to 6G.

Finally, I would like to thank Samarendra Nath Sur for his valuable work in assisting us with this Special Issue.

Dr. Dinh-Thuan Do
Prof. Dr. Adão Silva
Guest Editors

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• 6G
• Non-orthogonal multiple access (NOMA)
• Multiple-input multiple-output (MIMO)
• Millimeter Wave communication
• Intelligent reflecting surface (IRS)
• Unmanned aerial vehicles (UAVs)
• Cell-free networks
• Cognitive radio
• Resource allocation
• Soft computing