The 6GNet conference, held in October 2023, aimed to assess the progress of 6G research, a technology expected to be commercially available in 2030. Out of the ninety papers selected for presentation, seven were chosen for publication in the Annals of Telecommunications after a significant expansion. These papers provide detailed insights into several key research areas.

Before presenting the seven selected papers, we summarize the main research directions. They can be categorized into ten key areas.

The first area focuses on achieving ultra-high data rates, in the order of Gbps per user and several Tbps per antenna. This opens the door to applications requiring massive bandwidth, such as 16 K videos or immersive virtual reality (VR) environments.

The second area investigates extremely low latency, going significantly beyond 5G by reaching below a millisecond. This would enable perfect real-time communication for applications such as connected vehicles, telesurgery, and brain-computer interfaces.

6G will likely utilize additional, much higher frequency bands than 5G, including millimeter waves (above 100 GHz) and the terahertz (THz) spectrum. These frequencies allow for ultra-high data rates but have a limited range and require research into new antennas and infrastructure. This forms the third research area.

The fourth area is well known: the introduction of massive artificial intelligence, incorporating relatively traditional technologies like machine learning but also generative AI, giving rise to LLMs (large language models), SLMs (small language models), and enhancement technologies like fine-tuning and RAG (retrieval-augmented generation). 6G networks are expected to be automatically driven by AI, allowing for intelligent resource management. This includes dynamic bandwidth allocation, data path optimization, and failure or congestion prediction. AI will also be crucial for the energy efficiency of networks.

The Internet of senses is often cited as an important area to enable 6G to go beyond the Internet of things (IoT), where neural interfaces and connected devices will enable multisensory experiences (touch, taste, smell). This would revolutionize fields like medicine, immersive communication, and entertainment.

The sixth area corresponds to holographic and immersive communications, facilitating the transmission of real-time holograms, enabling immersive meetings or events remotely, and revolutionizing the way we interact in virtual and physical environments.

A key concern is energy savings and sustainability. Eco-design will be at the heart of the chosen architecture. 6G networks will be designed to be energy-efficient, with resource management mechanisms aiming to reduce energy consumption by devices and infrastructure. This forms the seventh research area.

The next research area is about global connectivity and universal coverage, which will enable serving all remote regions through an integrated system of satellites, drones, and terrestrial devices, creating a seamless large-scale communication network.

The ninth area concerns another strategic sector: data security and privacy. With the proliferation of connected devices, security and privacy issues are crucial. 6G will integrate advanced solutions based on quantum cryptography and authentication using biological or behavioral characteristics for enhanced security.

Finally, the tenth area is about machine-to-machine communication, either in D2D (device-to-device) mode or through vertical networks. This includes advanced sensor networks, smart objects, and AI agents. These communications are essential for Industry 4.0/5.0, smart cities, vehicle networks, and the optimization of processes in many sectors.

These research areas show that 6G will go well beyond improving 5G performance, with applications that will revolutionize various sectors such as healthcare, industry, entertainment, and city management. The technological challenges are still numerous, but the ongoing 6G research aims to create an interconnected and intelligent ecosystem.

The seven selected articles partially overlap with the research areas mentioned above.

The first article, titled “Organic 6G networks: ultra-flexibility through extensive stateless functional split,” proposes an organic 6G network architecture through a new functionality split based on the experience of IT software services. Furthermore, the authors provide an analysis based on the main 5G procedures, showing that the newly proposed architecture handles the re-selection of functionality significantly better, which is a cornerstone of high-speed scaling (especially scaling-out), as well as migration of functionality and users.

The second article, titled “Towards efficient conflict mitigation in the converged 6G Open RAN (Radio Access Network) control plane,” studies how the majority of near real-time network optimization use cases can be implemented harmoniously, to create an enhanced RAN control plane, underlining the functionality required from the central units of the RAN, the grouping, and the interaction of the network management decision. Analyzing the gap existing in the O-RAN architecture, the authors identify the required functionality and propose a management framework.

The third article, titled “Experimental demonstration of reflected beamforming and interference nulling at sub6GHz thanks to varactor based reconfigurable intelligent surface,” demonstrates experimentally that a reconfigurable intelligent surface designed for sub6GHz and using varactor technology can perform three-dimensional reflective beamforming and interference nulling. This result is achieved with a RIS prototype of 984 unit cells, thanks to a compact control circuit individually addressing and configuring the voltage of each unit cell, with a distinct voltage.

The fourth article, titled “A survey of public datasets for O-RAN: fostering the development of machine learning models,” surveys the primary public datasets available online that are considered in O-RAN papers. The authors identify the main characteristics and purpose of each dataset, contributing with a complement to their documentation. Also, the authors empirically showcase the viability of using publicly available datasets for machine learning applications within the O-RAN domain, such as spectrum and traffic classification.

The fifth article, titled “Guarding 6G use cases: a deep dive into AI/ML threats in All-Senses meeting,” sheds light on the use of AI/ML services, including generative large language model scenarios, in the all-senses meeting use case and their security aspects. This is achieved through threat modeling using the STRIDE framework and attack tree methodology. Additionally, the authors point out some countermeasures for identified threats.

The sixth paper, entitled “The use of statistical features for low-rate denial-of-service attack detection,” explores the potential of using statistical features for LDoS (low-rate denial-of-service) attack detection. Their results demonstrate the promising performance of these features in detecting such attacks. Furthermore, through ANOVA, mutual information, RFE, and SHAP analysis, they find that entropy and L-moment-based features play a crucial role in LDoS attack detection.

Finally, the last paper, titled “Towards intent-based management for Open RAN (Radio Access Network): an agile framework for detecting service-level agreement conflicts,” proposes the AGility in Intent-based management of service-level agreement Refinements (AGIR) system for implementing automated intent-based management in Open RAN. This modular system relies on natural language processing (NLP) to allow operators to specify service-level objectives (SLOs) for the RAN to fulfill without explicitly defining how to achieve these SLOs.

In conclusion, we hope this special issue provides an overview of the latest research on the key areas that will make 6G a revolution.