6G Use Cases and Scenarios: A Comparison Analysis Between ITU and Other Initiatives

Abstract

In the next decade, the amount of network traffic is estimated to reach Zettabytes. The future International Mobile Telecommunications-2030 (IMT-2030) standard of mobile networks, known as 6G, introduces an important paradigm shift in the context of wireless communication systems thanks to capabilities such as low latency and high data rates. Official documents on 6G standardization have been released by the International Telecommunication Union (ITU). However, other visions and use cases of 6G have been proposed by industrial stakeholders and research institutions, thus generating a multitude of use cases and usage scenarios that are only apparently different from each other. This paper would contribute to providing a holistic vision of the 6G-enabled use cases and potentially impacted vertical market sectors. The differences and similarities between what has been proposed by ITU and other initiatives are identified through a comparison based on the technological characterization of use cases and of the considered vertical market sectors. The main findings presented in this paper demonstrate that many of the use cases proposed by ITU and by the other initiatives are almost identical in many cases.

1. Introduction

In the next years, wireless communication networks will be characterized by several technological trends. According to [1], it is estimated that the number of 5G mobile subscriptions worldwide will reach $1.6$ billion by the end of 2023 and the mobile data traffic will increase up to 56 GB per month for a single smartphone by the end of 2029. The International Mobile Telecommunications-2030 (IMT-2030), known as 6G, is expected to be launched in 2030, and the related system studies and analysis activities have already begun. According to the ITU IMT-2030 roadmap [2], the standard development will proceed from 2027 to 2030, and then the system development and standard improvement will follow. In November 2023, the International Telecommunications Union (ITU) approved Recommendation ITU-R M.2160 [3], which contains the IMT-2030 framework description. It is envisaged that it will have a strong impact on shaping a “more inclusive” information society and overall sustainability. This is in line with the United Nations Sustainable Development Goals (SDGs) [4].

In addition to ITU, other entities, e.g., institutions and the most important companies involved in the telecommunication sector, have started their activities on 6G by providing contributions and releasing their visions of and perspectives on 6G. In particular, the HEXA-X is a European research project funded by the H2020 research framework and started in 2023. It is one of the most representative initiatives on 6G, and it aims to research digital technologies connecting people, and physical and digital objects. The 6G Industry Association (6G-IA) is another important initiative focused on 6G and funded by the European industry and research ecosystem. It defines the vision of private companies operating with 5G, and its scope is to provide research and development contributions to the 6G system. The Next G Alliance (NGA) is a research initiative carried out by US industries and research institutions aiming to identify potential opportunities and impacts generated by the introduction of 6G. The Next-Generation Mobile Network (NGMN) Alliance is a forum joined by the most important worldwide mobile network operators (MNOs) and industry stakeholders in the mobile communication sector. The NGMN started to identify the major opportunities provided by the future 6G system.

After an in-depth analysis of the ITU official documents and the other considered initiatives on 6G, we have seen a “disordered” proliferation of other scenarios and visions on 6G. This could lead to confusion in readers due to the fragmentation of ideas among ITU and other initiatives. This is evidenced by the different descriptions of seemingly similar scenarios in terms of objectives, technologies, applications, etc. Another important element we consider in this paper concerns the interests and developments of the vertical market sectors in which 6G will find application and a potential impact.

Below, we first aim to understand whether the use cases and scenarios proposed by ITU and the other initiatives, even though described differently, could instead be considered similar in terms of their main enabling technologies and the services/applications required for the implementations. Thus, one of the main goals of this paper is to search for analogies and to evidence differences among the proposals from 6G initiatives and ITU. A similar analysis will be conducted for some reference vertical market sectors we have selected in this paper. In particular, we try to understand whether the objectives of the vertical market sectors can be categorized from a technological point of view (similarly to what has been carried out for the use cases and scenarios) and also if the studies and standardization activities promoted by ITU and other initiatives can cover the needs of the main vertical market sectors.

The analysis method introduced in this paper allows us to assess the similarities and differences between the use cases and the scenarios proposed by ITU and the other initiatives. The direct analysis and comparison of use cases starting from the available documents is impossible in practice and useless. Every initiative adopts its terminology and conventions to describe use cases and scenarios. For this reason, in our analysis, we have introduced an objective reference to carry out the comparison. For this purpose, the main idea is to identify and characterize each scenario/use case and each vertical market sector in terms of the main technologies, applications and services that are deemed to be necessary for practical implementation. We then use this characterization to compare and evidence similarities and differences among the use cases/scenarios as well as among vertical market sectors. It also allows us to assess how the proposed use cases and scenarios match the needs of the vertical market sectors and the visions of other stakeholders.

The paper is organized as follows. In Section 2, we summarize the main aspects concerning the activities of ITU in the 6G area. In Section 3, Section 4, Section 5 and Section 6, we illustrate the main characteristics of the use cases/scenarios proposed by the other initiatives on 6G, such as HEXA-X, 6G-IA, NGA, and NGMN. In Section 7, we illustrate the 6G vision proposed by single vendors in the telecommunications sector, such as Ericsson, Huawei, and ZTE. In Section 9 and Section 10, we characterize the 6G use cases and vertical market sectors, respectively, in terms of required main technologies, applications and services. Section 12 describes the approach adopted for the comparative analysis of all proposed use cases and vertical market sectors. Results are presented in Section 13, detailing the methodology adopted for the comparative analysis, while conclusions are drawn in Section 14.

2. The ITU Activities on 6G

ITU Preliminary Work on 6G System

In November 2022 the ITU Radiocommunication Sector (ITU-R) published the Recommendation ITU-R M.2156 [5] concerning the preliminary work on IMT-2030, already known as 6G, including the usage scenarios and use cases. In November 2023, a second ITU-R Recommendation [3], was released on the 6G framework to finalize the proposed usage scenarios and their related capabilities. From 2024 to 2027, the requirement definition is expected, as per the ITU roadmap shown in Figure 1.

In the ITU document [3], the 6G usage scenarios are related to the SDGs in terms of (i) inclusivity, (ii) ubiquitous connectivity, (iii) sustainability, (iv) innovation, (v) enhanced security, (vi) privacy, and (vii) inter-working. The future 6G should guarantee connectivity to everyone worldwide and expand the coverage of broadband services. 6G should be economically, socially, and environmentally sustainable. It should also be innovative in terms of innovative technologies enhancing usability and improving security, privacy, and resilience from the end user perspective. Finally, the network infrastructures of the next wireless communication systems will be compliant with 3GPP standards and interoperable. They will also enable the inter-working between Terrestrial Networks (TNs) and Non-Terrestrial Networks (NTNs).

The ITU’s 6G usage scenarios are summarized in Figure 2.

Three of the scenarios in Figure 2 have been derived from those defined for 5G, i.e., enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLCs), and massive Machine Type Communications (mMTCs). These are now indicated as immersive communication, massive communication, and hyper-reliable and low-latency communication. The three new usage scenarios focus on (i) ubiquitous connectivity, (ii) integrated sensing and communication (ISAC), and (iii) AI and communication. Immersive communication focuses on enhanced mobile services where humans and machines strongly interact. Significant examples focus on communications for immersive mixed reality (XR); remote multi-sensory telepresence; holographic communications; mixed traffic of video, audio, and environmental data with time synchronization; and standalone support of voice. Massive communication considers scenarios with a huge number of interconnected devices, even including sensors and actuators. Typical examples include innovative applications in smart cities, oriented to logistics, health, agriculture, energy, and environmental monitoring. HRLLC constitutes the enhancement of the IMT-2020 URLLC scenario. It includes all applications that are demanding in terms of reliability and latency. Some examples include full automation, control, and operations in an industrial environment. Moreover, robotic applications, emergency services, telemedicine/tele-surgery, and electrical power monitoring can be added. Ubiquitous connectivity aims to provide connectivity everywhere and especially in digital divide areas, such as rural or sparsely populated areas. Typical scenarios include the Internet of Things (IoT) and mobile broadband communication. The ISAC is capable of providing intelligent sensing in wide areas and location information. Typical use cases focus on mapping environment reconstruction, motion recognition, tracking, emergency or disaster monitoring, surveillance, and assisted navigation. It also includes data on AI, XR, and Digital Twin applications for building reconstruction. Finally, the AI and communication scenario considers distributed computing and AI-enabled applications for consumer and corporate customers. AI-as-a-Service (AIaaS) is the emergent paradigm allowing customers to develop their AI-based applications using the available AI tools. Examples can be found in assisted automated driving, autonomous intelligent devices for the eHealth sector, data offloading, support of Digital Twins and assisted collaborative robots (Cobots).

To realize the 6G scenarios, ITU has identified a specific list of system capabilities for 6G that enhance those described in IMT-2020 in Recommendation ITU-R M.2083 [6]. The system capability can be specified for one usage scenario in a different way in terms of performance requirements, frequency range, bandwidth, deployment scenario, etc.

Table 1. 6G’s capabilities [3].

6G Capabilities	Details
Peak data rate	Maximum data rate the user terminal can achieve. Possible values are 50, 100, 200 Gbit/s.
User-experienced data rate	Data rate the user terminal can achieve in a ubiquitous modality. Possible values are 300 Mbit/s and 500 Mbit/s.
Spectrum efficiency	Measure of the average data throughput per single unit of spectrum resource and per cell. Possible values are 1.5 and 3 times greater than 5G cases.
Area traffic capacity	Total traffic throughput served per geographic area. Possible values are 30 Mbit/s/m2 and 50 Mbit/s/m2.
Connection Density	Total number of devices deployed per unit area. The target value could be 106 or 108 devices/km2.
Mobility	Maximum speed able to guarantee the target QoS levels and a seamless data transfer. The target value could be 500 and up to 1000 km/h.
Latency	Measure of the time needed by the destination to receive a specific packet over the radio interface. Possible values are 0.1 and up to 1 ms.
Reliability	Capability to transmit data successfully within a specific time interval over the air interface. Target values could be 1, 5, and 7 and up to 10.
Coverage	User access to communication network in a specific area. It is measured by the link budget analysis (cell edge distance).
Positioning	Approximate position of connected devices. Positioning accuracy target values could be from 1 to 10 cm.
Sensing-related capabilities	Advanced functionalities added to the radio interface, e.g., velocity estimation, object detection, localization, and imaging.
Applicable AI-related capabilities	Additional functionalities supporting AI-based enabled applications, e.g., distributed processing and learning and AI computing.
Security and resilience	Security aims to guarantee data confidentiality, integrity, and availability. Resilience indicates the network’s ability to work after an attack.
Sustainability	The network and devices should minimize environmental impact in terms of CO2 gas emissions during the overall lifecycle. It can be measured by the energy efficiency, as the number of bits exchanged per a single energy unit (bit/Joule).
Interoperability	Network ability for transparent use access through different system entities.

summarizes the main 6G capabilities that have been identified.

In the following sections, we describe in more detail the 6G proposals from other initiatives.

3. HEXA-X Initiative

The HEXA-X is a research project funded by the European Commission within the H2020 Research Framework. It focuses on B5G/6G vision and the intelligent fabric of technology enablers connecting the human, physical, and digital worlds. It originated from the 5G Infrastructure Public–Private Partnership (5G-PPP) initiative [7,8]. The HEXA-X project involves scientific institutions, universities and stakeholders from industry [9]. The research project activities are characterized by different aspects including societal, economic, regulatory, and technological trends by 2030. HEXA-X aims to provide an important contribution to the European industry leadership within the context of the next communication networks, such as 6G, which will seamlessly integrate TNs, NTNs and IoT. End users who able to access the next communication networks will be humans, physical objects, machines, physical robots, software chatbots and many others. The project aims to improve efficiency and resilience in the physical world through Digital Twins. They enable better planning and control, AI assistance and immersive communications between humans and the digital world. The results of the project are presented in four planned demo activities [9]. In this way, the HEXA-X vision on 6G aims to enable the seamless unification of physical, digital, and human worlds through a new ecosystem of networks, sub-networks, and advanced radio and multimedia technologies for the devices. From a social perspective, by the HEXA-X vision, future networks should be designed by a human-centric approach (including human-in-control) and should account for the human perspective(s) in every design phase [10,11]. For this reason, the HEXA-X vision for 6G aims to create a European-led effort of research and development toward 6G, focusing on trustworthiness, security, privacy, sustainability, and digital inclusion. To this purpose, six key research challenges have been identified. These include connecting intelligence, aggregating multiple types of resources, transforming networks into energy-optimized digital infrastructure, prioritizing global service coverage, providing extreme experience, and ensuring trustworthiness. It is left to the 6G system to manage (i) multiple types of resources, (ii) guarantee sustainability and carbon neutrality, (iii) reduce the digital divide, and (iv) introduce communication security to guarantee confidentiality, integrity, and availability. From a business perspective, according to HEXA-X, the 6G will impact several vertical market sectors, and this is thanks to the convergence and platform-based ecosystem of connectivity, data, and specialized services. Future ecosystems need open value configurations and decentralized power configurations, focusing on specific user requirements across several industrial sectors. HEXA-X phase II has provided an updated description of 6G use cases, requirements, and Key Performance Indicators (KPIs) for the technology design and implementation phases [11]. The project aims to address sustainability while considering environmental, social, and economic aspects as three key pillars of 6G. All use cases have been evaluated concerning these three pillars and considering potential benefits and unintended negative consequences. The adopted approach includes an elaborate in-depth analysis, the introduction of sustainability challenges, risk analysis, mitigation strategies, and the development of Key Value Indicators (KVIs). The project has identified the six families of use cases listed in

Table 2. HEXA-XII use cases [11].

HEXA-X-II Use Cases	Characteristics
Immersive experience	XR technology enhances the virtual environment, allowing human interaction through 3D images and videos. Potential applications include collaborative and hybrid meetings, classrooms, immersive gaming and virtual tours.
Collaborative Robots	Physical robots, intelligent and capable of interacting with humans, are used in cooperative logistics, manufacturing, autonomous construction, self-driving agriculture, and smart workshops.
Physical Awareness	Network-Assisted Mobility uses sensing and positioning features for intelligence tracking, navigation, and trajectory prediction. It includes autonomous drone transport, assisted vehicles, and cruise control.
Digital Twins	Digital Twins (DT) are digital models of real objects controlled in real-time using AI-based software. They can be used in manufacturing plants, industrial systems, water management, and traffic management in smart cities.
Fully Connected World	6G aims to provide seamless mobile broadband services with high Quality of Experience (QoE) through ubiquitous network access and interworking of TNs and NTNs.
Trusted Environments	6G focuses on digitalized places, providing high-level protection for private data, offering Human-Centric Services, precision healthcare, safe environments, and public safety services.

. These include immersive experience, collaborative robots, physical awareness, Digital Twins, fully connected world, and trusted environments. Each one has its representative use case(s) displaying its key aspects. Specific problems related to the limitations of current technologies and innovative capabilities to create demand for new services have been also analyzed in the HEXA project.

4. 6G Industry Association (6G-IA)

The 6G-IA is an initiative by European Industry and Research, and it represents private companies of 5G PPP and the Smart Networks and Services Joint Undertaking (SNS-JU) [12]. It focuses on future communication networks and services, and it aims to contribute to European leadership in BY5G/6G research and development.

The 6G is considered a transformative technology that will revolutionize the way enterprises operate and do business. It will enable convergence in areas such as connectivity, robotics, intelligent transport systems, cloud, and secure commerce. 6G will also create universal digital replications of real-world entities and advanced emulation platforms, allowing for Digital Twinning in various sectors, e.g., manufacturing, smart city, etc. In the case of the transportation system, the possibility of emulating in the lab a communication system to manage and control a vehicle (e.g., a train) is very important in developing and testing the communication system before its test on the field, [13]. This approach can reduce the costs for the development of the system and the new related services. The widespread deployment of 5G has led to a new era with distributed cell-free networks operated by millions of players. The need for the remote operation of converged ICT and OT platforms will require the optimization of fixed-wireless connectivity infrastructure. The differentiation between 6G and 5G focuses on global solutions that require significant changes in market structure and business models. Regulations, such as multi-level net neutrality, will be needed to ensure fair competition and open access to 6G specialized connectivity. The indications and opinions of the 6G-IA members are detailed in [14] along with potential services, related use cases, and key strategies. The key strategies that have been identified are listed in the following points:

• 6G Technological Sovereignty, in terms of components and microelectronics, open SNS solutions, cloudification and distributed computing, network intelligence, security and privacy, and knowledge base;
• Environmental, societal, and economic sustainability (according to UN SDGs).

The sustainability approach includes UN SDGs and the European Green Deal, with Key Values (KVs) including trust, digital inclusion, personal health, privacy, and confidentiality. KVIs and KPIs assess technological value and societal challenges based on the 2030 Agenda for Sustainable Development [15]. The 6G-IA use cases are summarized in

Table 3. 6G-IA use cases [14].

6G-IA Use Cases	Characteristics
Emergency response and warning systems	It aims to reduce emergency response times, support environmental sustainability in terms of surveyed natural habitats, favor the increase in protected and surveyed natural habitats, and preserve climate through user confidence in advanced digital devices.
Smart city with urban mobility	It supports environmental sustainability and personal health in terms of urban transport optimization and avoiding injuries.
Personal health monitoring and actuation everywhere	It contributes to the secure management of the user health data and to optimize cost-saving in the health care system.
Living and working everywhere	It supports the reduction in the time for transport and good life in rural areas, encouraging the access to the internet.
Sustainable food production	It supports the reduction in environmental footprint in the agriculture sector and the increase of agriculture productivity.

.

5. Next G Alliance (NGA)

NGA is a US initiative contributing to the USA’s leadership within the future wireless technology sector [16]. NGA is focusing on technology commercialization and private companies’ contribution. This initiative identifies 6G vertical market sectors like automotive, education, gaming, IoT, smart cities, public safety, mining, eHealth, and agriculture. 6G applications are anticipated to significantly expand North American markets by impacting several aspects of life, society, and industries, thereby transforming the way people live and work. These applications are expected to improve everyday living by providing services like healthcare, caregiving, and intelligent travel assistance. The workforce required to support these services will grow more prominent due to the global trend of an aging population. The need for intelligent assistance for humans is considered a great market potential and business opportunity. Moreover, in [17], NGA specifies four categories of use cases focused on improving people’s lives and their interactions. These are described in

Table 4. List of use cases proposed by NGA, [17].

NGA Use Cases	Examples
Network-Enabled Robotic and Autonomous Systems	Online Cooperative Operation among a Group of Service Robots
	Field Robots for Hazardous Environments
Multi-Sensory Extended Reality	Ultra-Realistic Interactive Sport— Drone Racing
	Immersive Gaming/Entertainment
	Mixed Reality Co-Design
	Mixed Reality Telepresence
	Immersive Education with 6G
	High-Speed Wireless Connection in Aerial Vehicle for Entertainment Service
Distributed Sensing and Communications	Remote Data Collection
	Un-tethered Wearables and Implants
	Eliminating the North American Digital Divide
	Public Safety Applications
	Synchronous Data Channels
	Health Care—In-Body Network
Personalized user experiences	Personalized Hotel Experience
	Personalized Shopping Experience

.

The first NGA use case category is about network-enabled robotic and autonomous systems. It includes (i) online cooperative operation in a group of service robots and (ii) field robots for hazardous environments, including multiple service robots working together and field robots for mission-critical tasks.

The multi-sensory extended reality category comprises the following representative use cases: (i) ultra-realistic interactive sport, which is centered on drone racing, immersive gaming/entertainment on immersive gaming, and mixed reality co-design on remote collaboration within real and virtual worlds; (ii) mixed-reality telepresence use case focuses on 3D functionalities for remote social interactions; (iii) immersive education with 6G on remote schooling; (iv) high-speed wireless connection in the aerial vehicle for entertainment service on high-speed wireless connections in aerial vehicles for entertainment and service.

The distributed sensing and communications use case category is divided into other representative use cases, including remote data collection and un-tethered wearables and implants. The first one analyzes data collected by LEO satellites and IoT in rural areas. In particular, untethered wearables and implants focus on wireless wearables.

Public safety applications focus on solutions able to guarantee people’s safety using advanced multimedia technologies, such as high-resolution video, by enhancing rules, regulations, security, and policy enforcement. The monitoring of critical infrastructures is another crucial aspect to be supported by the future 6G system. For example, in the case of railway, the integration of IoT devices with TNs and NTN is crucial to monitor and control the movement of trains and to check their status and behavior [18].

The synchronous data channels use case relies on the health–care–in-body network and on advanced telemedicine and interactive remote monitoring for predicting therapy.

Personalized user experiences are the last use case category. It includes representative use cases enabled by advanced digital interaction, such as the Personalized Hotel Experience (e.g., enabling automated room services) and the Personalized Shopping Experience (e.g., within interactive and virtual stores and immersive product demos).

6. Next-Generation Mobile Network (NGMN)

The NGMN comprises major global mobile network operators and industry stakeholders. It has released several documents in 2023 concerning 6G use cases and analysis [19,20,21]. NGMN invited its members to contribute their views on future 6G capabilities. They identified about 50 use cases that have been grouped into the following four classes:

• Enhanced human communication. The advancement in human communication technology includes XR immersive holographic telepresence, multi-model communication for teleoperation, and intelligent interactions for sharing sensations, skills, and thoughts.
• Enhanced machine communication. The field of collaborative robotics involves autonomous devices equipped with sensors, including robot network fabric and interacting Cobots.
• Enabling Services. The technology offers high-accuracy localization, 3D tracking, Digital Twins, virtual worlds, automatic detection protection, and trusted services in digital healthcare, and smart industries.
• Network evolution. AIaaS includes trusted native AI, and it is a technology that focuses on energy efficiency and ubiquitous communication, and covers a wide range of applications.

Table 5. List of use cases proposed by NGMN [20,21].

NGMN Use Cases	Examples
Enhanced Human Communication	XR Immersive Holographic Telepresence Communication
	Multimodal Communication for Teleoperation
	Intelligent Interaction Sharing of Sensation, Skills Thoughts
Enhanced Machine Communication	Robot Network Fabric
	Interacting Cobots
Enabling Services	3D Hyper-Accurate Positioning, Localisation, and Tracking
	Interactive Mapping
	Digital Healthcare
	Automatic Detection, Recognition and Inspection
	Smart Industry
	Trusted Composition of Services
Network Evolution	Native Trusted AI (AIaaS)
	Coverage Expansion
	Autonomous System for Energy Efficiency

summarizes the relationship between the use cases and the four classes that have been identified:

These four classes are now detailed in terms of their representative use cases.

The enhanced human communication class includes use cases on XR immersive holographic telepresence communication, multimodal communication for teleoperation, and intelligent interaction sharing of sensation, skills, and thought. The first use case underlines the role of human-centric extended immersive and 3D reality, such as Virtual Reality (VR), Augmented Reality (AR), and MR, together with holographic telepresence in work and for social interaction. Multimodal communication for teleoperation focuses on human multimodality information, including audio, video, taste, odor, haptic, and emotion, and on how it could be transferred over communication networks. The intelligent interaction sharing of sensations, skills thoughts is focused on Brain–Computer Interfaces (BCIs) enabling the real-time sharing of sensations and thoughts between humans and machines, transforming the human–machine interface.

The second class, enhanced machine communication, is mainly focused on robot network fabric and interacting Cobot use cases. The first one is about the role of 6G in traffic management to ensure safe, collision-free, and efficient traffic in a heterogeneous environment. Examples are autonomous mobile robots, drones, and Automated Guided Vehicles (AGVs). The second one is about Cobots. They are expected to enhance human–robot interaction to interpret human actions, respond in a trustworthy way, and assist humans efficiently and safely.

The third class, Enabling Services, includes the following representative use cases: 3D hyper-accurate positioning, localization, and tracking, interactive mapping, digital healthcare, automatic detection, recognition and inspection, smart industry, and the trusted composition of services. The first example is on the high-accuracy 3D localization and advanced tracking capabilities, particularly in indoor environments (e.g., smart factories, warehouses, hospitals), while the second one is on the interactive maps created starting from the representations of physical assets to enable efficient large-scale system management and real-time environmental representation. Digital healthcare is another important use case to be considered in the case of the advanced 24/7 monitoring of vital parameters through wearable devices. The automatic detection, recognition, and inspection analysis of the usage of 6G features in different applications, including security screening at airports, smart hospitals, and intelligent factories. The smart industry objectives focus on reducing carbon footprints and resource circularity and reducing daily commutes due to COVID-19 concerns. Finally, the trusted composition of the service use case is centered on the network convergence for enhancing human and machine communication and enabling a trusted composition of services for dynamic and complex use cases.

7. 6G Initiatives from Single Vendors

The main vendors from the telecommunication sector have published documents and reports on the 6G use cases and scenarios. In [22], Ericsson defined the following four use case categories for the 6G system:

• The Internet of Senses: data from sensors, images, audio and video, and haptics enable new digital sensory experiences;
• Connected intelligent machines: AI-based intelligent devices (e.g., Cobots);
• Digitized and programmable physical world: digital copy of a real object using AI-based software (e.g., DT);
• Connected sustainable world: ICT contribution to energy efficiency strategies.

In [23], Huawei underlines the important role of 6G as a game changer for the economy and society and as an enabler for the new paradigm of the future Intelligence of Everything (IoE). The sustainability characteristic has been also considered. Nokia sees the 6G system as the link between three worlds, physical, digital, and human, and refers to the same 6G vertical market sectors indicated by NGA [24]. In [25] ZTE identifies three main 6G scenarios characterized by the implementation of AI-based technologies within the communication networks:

• Supporting the enhancement of 5G-advanced mobile technology to improve network efficiency;
• Value-added applications based on AI (e.g., metaverse, immersive XR, Digital Twins, and autonomous vehicles);
• Sustainable communication networks thanks to AI-native technologies (e.g., resource awareness and allocation, dynamic control in case of 6G multiple operators, and multiple frequency bands).

8. Security Aspects of the Proposed 6G Use Cases

ITU mentioned security (together with resilience) as one of the 6G capabilities. According to xxx, security is related to the necessity to secure data, networks, platforms, and devices against cyberattacks. Future 6G networks enhance security and resilience since they must be secure by design. Although security properties must be guaranteed in all six ITU usage scenarios, in the Integration of Sensing and Communication and Massive Communication, the need for guaranteeing high security levels is stressed, due to the huge number of involved systems and devices with different characteristics. ITU also mentions some potential technologies to improve 6G security, such as Blockchain, differential approach to privacy, quantum technology, and Physical-Layer Security (PLS) technologies. According to the 6G-IA initiative, future systems will be more intelligent, powerful, and dynamic. In this context, trust is a crucial aspect to consider in conjunction with security (e.g., in terms of authentication, authorization, and non-repudiation). Trust is also related to functional and non-functional criteria, such as the approach to data management and performance, respectively. Since we will assist in a powerful convergence of digital, physical, and personal environments, a lot of data can be collected. The efficient control of data integrity and security is crucial. 6G IA remarks on the need for network and service security, since 6G will be characterized by high complexity and fragmentation. The potential approaches are evidence, such as zero-touch micro-segmentation and slicing, together with distributed AI/ML functions and models. The disruptive strategies and concepts for 6G security are also described beyond classical approaches, such as virtualization, softwarization, deception, or moving in terms of target defense, a holistic approach during the entire lifecycle, and “security as a service” based on cloud technology. Finally, 6G IA considers hardware security, AI/ML-assisted security, and the impact on professional skills as important topics to be considered carefully. The HEXA-II initiative considers the social aspects of security, especially in terms of privacy risks, since the 6G will provide connectivity and services anywhere for everyone. Privacy and security are important requirements to be considered both for Terrestrial Networks (TNs) and Non-Terrestrial Networks (NTNs). For example, services for public safety during big events are important, such as for managing situations of rising emotion, facial recognition, etc. HEXA-II also identifies the privacy/security, reliability/availability, and service continuity concepts as the main constraints and challenges for the next 6G. According to NGA, the regulatory requirements at the national and regional levels are to be satisfied by the next 6G, especially in terms of national security and safety. In addition, customer security and privacy have to be considered by designing services and applications. Trust, security, and resilience are some of the most important objectives of the Next G Alliance activities. Most identified use cases require a high level of security and resilience. In the case of the Online Cooperative Operation among a Group of Service Robots (SOBOTs), security is needed to manage data from healthcare and critical applications. If field robots are used in hazardous environments, they need to use the output provided by AI/ML algorithms to identify the best decision to adopt. In the case of public safety applications, security is crucial for monitoring and managing data acquired in a smart city environment, while for synchronous data channels, it supports authenticity. Finally, in the case of healthcare in-body networks, and personalized user experiences, the use of data needs to be secured and managed by adopting a privacy-oriented approach. NGMN also considers security, trust, and privacy as crucial elements to be considered by future technologies in several use cases. In the context of enhanced human communication, innovative systems for automatic detection, recognition and inspection must operate guaranteeing security during monitoring applications (e.g., in airports). Advanced human–machine interfaces must also guarantee the right levels of privacy and security. From the network perspective, its evolution is based on a native trusted AI, while the advanced services need to guarantee the data’s trustworthiness.

9. 6G Use Cases Considered for the Analysis

From the description in the previous sections, a great variety of use cases and scenarios emerge that have been proposed by the different actors in the telecommunication sector. In

Table 6. The 6G initiatives and the corresponding use cases.

6G Initiatives	ID Use Case	Use case	Acronym
ITU	1	Immersive Communication	ITU-IC
	2	Massive Communication	ITU-MC
	3	Hyper-Reliable and Low-Latency Communication	ITU-HRLLC
	4	Ubiquitous Connectivity	ITU-UC
	5	AI and Communication	ITU-AIC
	6	Integrated Sensing and Communication	ITU-ISC
HEXA	7	Immersive experience	HEXA-IE
	8	Collaborative Robot	HEXA-CR
	9	Physical Awareness	HEXA-PA
	10	Digital Twin	HEXA-DT
	11	Fully Connected World	HEXA-FCW
	12	Trusted Environments	HEXA-TE
6G-IA	13	Emergency response and warning systems	6GIA-ERWS
	14	Smart City with Urban Mobility	6GIA-SCUM
	15	Personal Health Monitoring and Actuation Everywhere	6GIA-PHM
	16	Living and Working Everywhere	6GIA-LWR
	17	Sustainable Food Production	6GIA-SFP
NGA	18	Networked-Enabled Robotic and Autonomous Systems	NGA-NERAS
	19	Multi-Sensory Extended Reality	NGA-MSER
	20	Distributed Sensing and Communications	NGA-DSC
	21	Personalized User experiences	NGA-PUE
NGMN	22	Enhanced Human Communication	NGMN-EHC
	23	Enhanced Machine Communication	NGMN-EMC
	24	Digital Healthcare	NGMN-DH
	25	Smart Industry	NGMN-SI
	26	Network Evolution	NGMN-NE

, we summarize the 6G use cases proposed by ITU and by the other stakeholders that are considered in our analysis. In the same table, the corresponding acronyms are also indicated.

As indicated in Section 6, the NGMN initiative has proposed five use case families. From a careful analysis of the Enabling Services family in addition to the two use cases, Digital Healthcare and Smart Industry, we have observed that the following technologies and functionalities have also been considered as use cases: hyper-accurate positioning, localization, tracking and interactive mapping, automatic detection and recognition, and inspection. To our opinion, these should be considered more properly as necessary technological components for the realization of many of the use cases defined in NGMN and also in ITU and other initiatives. For this reason, we have excluded them from the subsequent analysis.

10. Vertical Market Sectors

Another main goal of the analysis carried out in this paper is to evidence if and how the 6G use cases proposed by ITU and by the other initiatives can impact the most important vertical market sectors. Different consulting companies and stakeholders in the TLC sector have published different market analyses based on their needs and visions. According to the authors, APTIC is among the most complete and includes most of the content published by the main players in the telecommunications sector. We started from the list published by APTIC and tried to extract our list, WHICH includes most of the vertical market sectors, not only those in the telecommunications market. In selecting the vertical market sectors of interest, we have started from the exhaustive list of vertical market sectors provided by APTIC Consulting [26], which has been summarized in

Table 7. The list of vertical market sectors provided by APTIC Consulting.

ID	Vertical Market Sectors
1	Aerospace and Defense
2	Agriculture and Forestry
3	Chemicals
4	Computers and Technology
5	Construction and Real Estate
6	Education and Training
7	Energy and Utilities
8	Entertainment and Media
9	Financial Services
10	Food and Beverage
11	Healthcare and Pharmaceuticals
12	Hospitality and Tourism
13	Information Services
14	Manufacturing
15	Mass Media
16	Professional Services
17	Retail and Consumer Services
18	Technology
19	Telecommunications
20	Transportation and Logistics
21	Waste Management and Environmental Services
22	Water

.

Starting from the list in Table 7, we have selected sixteen vertical market sectors in

Table 8. The list of 6G potential vertical market sectors we derived from APTIC Consulting.

ID	Vertical Market Sectors	Acronym
1	Factories of the future	FFE
2	Energy	EN
3	eHealth1 (personal monitor)	EH1
4	eHealth2 (telesurgery)	EH2
5	Automotive	AUT
6	Entertainment	ENT
7	Agriculture	AGR
8	Logistics	LOG
9	Environment	ENV
10	eGov	EGO
11	Smart City	SC
12	Transportation	TRA
13	Education	EDU
14	Emergency	EME
15	Cultural Heritage	CH
16	e-Commerce	EC

that are of interest for the telecommunications sector and 6G. The acronyms will be used in the following to identify the single vertical market sectors that have been indicated in the same table.

Factories of the future refer to industries characterized by a high level of automation, even based on the wide usage of intelligent devices. The energy indicates the energy sector concerning electric and power efficiency. We have decided to divide the huge e-health vertical market sectors into two parts, indicated for brevity as eHealth1 and eHealth2. The first refers to remote monitoring (temperature, acquisition of pulse and respiration rate, etc.) and tele-assistance services. The second one concerns more demanding e-health applications such as tele-surgery. The technologies and applications/services involved in the two markets can be very different. The automotive sector considers vehicles, including those with assisted and autonomous driving features. The entertainment sector also considers applications based on AR/VR/xR for gaming. The agriculture sector instead considers all the digital technologies supporting farming processes. The logistics sector considers the application of communication technologies in all the procedures for the shipping and picking of goods.

The environment sector takes into account the methodologies to be used for monitoring environmental and pollution conditions in terms of temperature, pressure, humidity, and CO₂ emissions. The e-government sector considers all applications and services that public administrations can render available in favor of the citizens. The smart city considers the digital applications and features for each smart city segment including health, mobility, intelligent traffic management and so on. The transportation sector refers to the technologies used to monitor, control, and optimize the mobility of people and goods through different means of transport, i.e., multi-modal and integrated transport. The education sector considers applications for learning and teaching. The emergency sector includes all the services and technologies to be used in the case of large-scale emergency events, including, for example, earthquakes and water floods. Cultural heritage comprises the digital applications needed to support art fruition by the end user (e.g., 3D visualization). Finally, e-commerce considers all the applications enabling the digital buying and selling of goods.

Table 9. The mapping of vertical market sectors provided by APTIC Consulting and by the present paper.

Vertical Market Sectors (from APTIC Consulting)	Vertical Market Sectors (Our Work)	Note
Aerospace and Defense	Factories of the Future (FFE)
Agriculture and Forestry	Agriculture (AGR)
Chemicals	Agriculture (AGR)	-
Computers and Technology	-	These are enabling technologies
Construction and Real Estate	Smart City (SC)	-
Education and Training	Education (EDU)	-
Energy and Utilities	Energy (EN)	-
Entertainment and Media	Entertainment (ENT)	-
Financial Services	e-Commerce (EC)	-
Food and Beverage	Factories of the future (FFE)	-
Healthcare and Pharmaceuticals	eHealth1 (personal monitor) (EH1); eHealth2 (telesurgery) (EH2)	-
Hospitality and Tourism	Smart City (SC)
Information Services	-	These are enabling technologies
Manufacturing	Factories of the Future (FFE)	-
Mass Media	Entertainment (ENT)	-
Professional Services	e-Commerce (EC)	-
Retail and Consumer Services	e-Commerce (EC)	-
Technology	-	These are enabling technologies
Telecommunications	-	These are enabling technologies
Transportation and Logistics	Transportation (TRA); Logistics (LOG)	-
Waste Management and Environmental Services	Environment (ENV)	-
Water	Smart City (SC)	-
-	Automotive	We separated it from the manufacturing
-	eGov (EGO)	Not included in the APTIC Consulting
-	Cultural Heritage (CH)	Not included in the APTIC Consulting
-	Emergency	Not included in the APTIC Consulting

explains the mapping of the list of vertical market sectors by APTIC in Table 7 and the list of sectors we have considered in this paper (see Table 8). In some cases, the vertical market sectors are identical, e.g., agriculture and transportation. In other cases, we split one vertical market sector into two connected vertical market sectors since they use different technologies (e.g., eHealth1 and eHealth2). Finally, some assumptions and approximations are needed to avoid excessive fragmentation. For this reason, some vertical market sectors are grouped considering common elements, e.g., the digital interaction with end user.s

As shown in Table 9, as an example, the chemicals from APTIC Consulting can be mapped with the agriculture (AGR) sector we have considered in this paper. Similarly, construction and real estate have been cast in the smart city sector and the Food and Beverage with Factories of the Future (FFE). Even hospitality and tourism and water can be framed in smart cities, due to the role of digital technologies in managing the applications related to tourism and water management (increasing efficiency, implementing strategies for saving water, etc.) [27,28]. Waste management and environmental services can be cast within the environment (ENV) sector. Finally, professional services can be cast within e-commerce (EC), since (i) this sector is not directly addressed by the main stakeholder and (ii) the involvement of people is requested through digital interaction. Instead, we consider computers and technology, information services, technology, and telecommunications as enabling technologies supporting one or more vertical market sectors. In Table 8, we have introduced new vertical market sectors not included in the APTIC’s list, such as e-gov (EGO), cultural heritage (CH), and emergency (EME). These have an important role within the actual 5G/BY5G and future 6G systems.

11. The 6G Enabling Technology Categories

This section summarizes the 6G enabling potential technologies mentioned in the scientific literature are summarized. In [29], the optimal use of wireless resources is underlined. In this sense, technologies at the physical layer, such as massive MIMO and mmWave technologies, can be considered for Tera Hertz (THz) frequencies above 300 GHz. Some use cases are presented. Smart city is one of them characterized by the Internet of Things (IoT), Cloud Computing, Fog and Edge Computing, etc. AI and ML are innovative features that will be included in the 6G networks. The paper also hypothesizes potential use cases, like education, digital agriculture, and seamless coverage anywhere using AR/VR, and future mobility. After an overview of the 6G vision, together with technical requirements and scenarios, ref. [30] lists some potential 6G-enabling technologies, such as ultra-massive MIMO and THz communications, advanced spectrum management, and new waveforms and modulation. In addition to AI and ML, the paper analyzes Reconfigurable Intelligent Surfaces (RISs), holographic radio, blockchain platforms, and Integrated Sensing And Communication (ISAC). Ref. [31] introduces the concept of Coherence Transition, which is the integration of holographic radio and photonics. According to the authors, these technologies at the PHY layer will be crucial components in the 6G network design and planning. Ref. [32] describes the main 6G-enabling technologies as THz communications, Reconfigurable Intelligent Surfaces (RISs), AI/ML, ultra-massive MIMO, and distributed intelligent computing networks. They have a strong impact on the most important features of the next 6G wireless networks, such as data rate, efficiency in terms of spectrum and energy efficiency, coverage, and reliability. Ref. [33] describes potential technological enablers and possible 6G use cases. The mentioned technological enablers are as follows.

• THz communications and optics;
• Full duplex and Sensing and localization;
• Multi-connectivity, virtualization, and low-power functionalities;
• Knowledge sharing and user-centric network architecture in terms of network intelligence.

In addition to AI and ML, ref. [34] introduces technologies such as VR, AR, XR, IoT, and blockchain platforms. Ref. [35] hypothesizes that 6G will be human-centered. Security and privacy are the most important requirements from the end user’s perspective. Moreover, applications with a high level of immersive degree are mentioned and described, such as Digital Twins, extended reality (XR) and Virtual Reality (VR). Other technologies at the network level are also analyzed, such as Cloud/Fog/Edge Computing, and heterogeneous networks. Finally, ultra-massive MIMO and optics are mentioned as advanced transmission schemes. According to [36], the most important features of the 6G system will be immersive reality, intelligent manufacturing, smart infrastructure, XR immersive communication, and Digital Twins. The list of the main technologies, applications, and services we have considered to characterize the 6G use case and the vertical market sectors is given in

Table 10. The most relevant 6G technologies.

Required Technologies Category	Technology ID	Technology Name	Acronym
Communication Technology	1	Broadband	CT-BRO
	2	Narrowband (IoT)	CT-NAR
	3	Very Low Latency	CT-VLL
	4	Extended Coverage	CT-EC
Localization Technology	5	GNSS/Other	LT
HCI Technologies	6	VR	HCI-VR
	7	AR	HCI-AR
	8	XR	HCI-XR
	9	Holography	HCI-HOL
	10	Virtual Personal Assistant	HCI-VPA
	11	Touchscreen, Keyboards	HCI-TK
Data Acquisition	12	Multimedia Sensors	DACQ-MS
	13	Active Detection/Ranging	DACQ-AD
	14	Environmental Sensors	DACQ-ES
	15	Wearables	DACQ-W
	16	Device Status Sensors	DACQ-DS
Actuators	17	Traditional Industrial Actuators	DACT-TIA
	18	Robot	DACT-R
	19	Cobot	DACT-C
	20	UAV	DACT-U
Management Platforms	21	Digital Twin	MP-DT
	22	Cloud	MP-C
	23	Edge Cloud Computing (ECC)	MP-ECC
	24	AI/ML	MP-AIML
	25	Virtualization	MP-V

with the corresponding acronyms. As shown in Table 10, the considered technological features have been grouped into the following six main categories:

• Communication Technology. This refers to the transmission technologies supporting specific use case applications. They can be broadband or narrowband (e.g., IoT). Moreover, they are also able to provide very low latency and extended coverage features.
• Localization Technology. This refers to both localization features and localization technologies, including the Global Navigation Satellite System (GNSS) or other technologies;
• HCI Technologies. This considers human–computer interface (HCI) communications, including VR, AR, MR, holography, and virtual personal assistants. Touchscreen and keyboard devices are also considered for the device remote control;
• Data Acquisition. This includes all sensors and technologies supporting the data acquisition process, e.g., multimedia sensors, active detection and ranging (e.g., Lidar, radar), environmental sensors, wearable sensors, and device status sensors.
• Actuators. This comprises technologies for actuators, e.g., robots, Cobots, Unmanned Aerial Vehicles (UAVs), and traditional actuators e.g., hydraulic, pneumatic, electric, thermal, and magnetic;
• Management Platforms and Applications. This refers to the hardware/software platforms running applications and providing services for orchestrating, managing/controlling systems, e.g., based on Digital Twins, cloud, AI, Machine Learning (ML), and virtualization. Edge Cloud Computing (ECC) is also considered due to its crucial role in advanced video streaming applications and the Content Delivery Network (CDN). These network components and technologies are already present in the legacy 5G networks, especially for multimedia and streaming applications. They can support 5–10 ms latency applications. Moreover, in the case of 6G, they are native and able to support 1 ms latency. This approach already forces the broadcaster company to identify new business activities that continue to also be present in the future 6G [37].

The communication technologies have been first classified into broadband and narrowband, as they provide different transmission capacities in terms of available bit rate per user. From an in-depth analysis of the descriptions of the use cases and looking at other papers on 4G and 5G, we have observed that the capabilities for a communication system to provide very low latency and extended coverage are important distinguishing features [6,38,39]. The very low latency capability is necessary for supporting latency-sensitive applications [40,41]. Extended coverage refers to the capability to guarantee access over relatively large (spatially extended) areas, e.g., metropolitan and wide areas.

The localization technology includes, in a broad sense, services provided by GNSS systems, such as the Global Positioning System (GPS) and/or localization services provided by local area technologies and from mobile radio systems [42]. HCI technologies are used to allow human–machine interaction [43,44]. These can include traditional or advanced components. The first ones can be represented by a keyboard and touchscreen (e.g., tablets). The second ones include devices implementing VR/AR/XR technologies, holography (with haptic devices able to reveal facial expressions, hand movements, etc.), and virtual personal assistants [45]. Within the data acquisition technologies, we have included multimedia sensors, as well as devices for active detection or ranging (e.g., Lidar or Radar), environmental sensors (e.g., humidity, pressure, pollution) and wearables for the monitoring of human vital signs (body pressure, body pressure, heart rate, and respiratory rate). With the data acquisition phase, the data are collected by the sensors. These data are used to be processed for making decisions and then to perform the corresponding action through the actuators. We grouped these devices into two main categories, traditional technologies (DACT-TIA) and advanced technologies for actuation, as in Table 10. In the first category, we have included hydraulic, pneumatic, electric, thermal, and magnetic, according to [46]. In the second category, we have included robot, Cobot, and UAV. Finally, in the management platforms and applications’ technologies, we have included all the services and (software) applications enabling the realization of 6G services running in the cloud and/or on the edge cloud platforms. Even AI/ML and virtualization techniques and technologies have been included in this category [47].

The mentioned technologies are important and relevant for each scenario we considered. For example, the immersive communication use case proposed by ITU foresees the inclusion of telepresence technology and holographic communications. For this reason, we considered technologies such as VR, AR, XR, holography, and virtual personal assistants. Touchscreen and keyboards are haptic devices. Multimedia sensors and active ranging devices are needed to create the 3D digital representation of the real objects and the surrounding environment. Finally, AI/ML is a valid support to automatize and predict actions, as well as to guide the end user. Within the physical awareness use cases from HEXA-X-II, we identified both broadband and narrowband as communication technologies since the drone is equipped with a plethora of sensors with different communication protocols. The extended coverage features and localization technologies have also been considered since the drone needs an extended availability of radio signals and information about localization.

12. Comparative Analysis

In this section, we describe the methodology we have adopted to compare the 6G use cases presented by ITU and the other initiatives. The results are discussed in the next section. Comparative analysis is carried out by analyzing the 6G use cases proposed by ITU and the other initiatives and the vertical market sectors. The flowchart detailing the comparison procedure is shown in Figure 3. The main purpose of this analysis is to provide an indication of how the proposed 6G use cases are in line with the necessities of the considered vertical market sectors and to evidence their impacts.

The comparative analysis of many use cases with vertical market sectors has been carried out, taking as reference the technological aspects. In particular, as shown in Figure 3, the analysis starts by identifying the main digital technologies, applications and services that are deemed to be the most relevant, (i) for the realization of each 6G use case and (ii) for the objectives of the selected vertical market sectors.

As indicated in the scheme in Figure 3, the comparative analysis starts with the characterization of the 6G use cases and the vertical market sectors in terms of the technologies and applications listed in Table 10. The results of this preliminary step are the generation of the two binary-valued matrices: (i) “Use cases vs. Technologies”, and (ii) “Vertical market sectors vs. Technologies” that are reported in Figure A1 and Figure A2, respectively, in Appendix A. The single entry in Figure A1 is a binary variable taking a value of 1 if the considered use case (row) requires (i.e., is enabled by) the considered technology/application (column) and 0 otherwise. Similarly, the single entry in Figure A2 is still a binary value taking a value of 1 if the selected vertical market sector (row) requires the selected technology/application and 0 otherwise.

These two matrices are then used to perform the analysis necessary to obtain the results summarized in

Table 11. Tables and corresponding output.

ID Analysis	Type of Analysis	Description of the Output
1	6G Use cases vs. vertical market sectors	Which and how much the proposed 6G use case is closer to the vertical market sectors
2	6G Use cases from other initiatives vs. ITU 6G usage scenarios	Which and how much the proposed 6G use case from other initiatives (stakeholders) is closer to the ITU 6G usage scenarios
3	All proposed 6G Use cases vs. All proposed 6G use cases	Which and how much the proposed 6G Use cases are close among them
4	Vertical market sectors vs. Vertical market sectors	Which and how much the identified vertical market sector is close among them
5	Technologies vs. 6G Use cases	Which and how much the identified most relevant technologies are used in each proposed 6G use cases
6	Technologies vs. Vertical market sectors	Which and how much the identified most relevant technologies are used in each vertical market sector

. These results also include the analysis and comparisons among (i) all the use cases proposed by the different stakeholders and (ii) the selected vertical market sector. Finally, we have conducted an analysis aimed at highlighting how the proposed use cases are in line with market trends and the requirements issued by the selected vertical market sector.

The first analysis tries to establish how the 6G use cases fulfill the requirements of the vertical market sectors in terms of required technology/applications and services. From this analysis, we can identify the 6G use case(s) matching the technology needs for each of the considered vertical market sectors. The second analysis compares the use cases from other initiatives with those proposed by ITU 6G usage scenarios. Its objective is to assess how the 6G use cases proposed by other stakeholders are close/far to/from those proposed by ITU. The objective of the third analysis is to identify the relationships among the ITU 6G use cases and those presented by other initiatives. This is useful to assess which use cases are closer from a technological point of view. A similar analysis is repeated for the considered vertical market sectors, so as to identify those sectors that are similar in terms of the required technologies/applications/services. Finally, in the last two analyses, we identify the technologies/applications/services that are most relevant for the considered 6G use cases and vertical market sectors.

To assess the similarity of use cases and vertical market sectors, we have used the normalized Hamming distance [48].

The number of positions by which two strings differ is indicated by the Hamming distance. The ratio of the Hamming distance to the string’s length is known as the normalized Hamming distance. A smaller normalized Hamming distance value indicates a greater similarity between the two strings. So, the normalized Hamming distance is calculated as the percentage of coordinates that differ [49]. This metric is evaluated concerning rows of the two matrices in Figure A1 and Figure A2 reported in Appendix A, according to the following formula:

$$d(x,y)=){\displaystyle \frac{1}{n}}\sum _{i=1}^n|x_i-y_i|$$

(1)

where n is the length of the row and $x_i$ and $y_i$ are the two binary values of the i-th cell in the x and y row, respectively. The lower the Hamming distance, the more similar the two vectors are. To quantify the degree of similarity so as to facilitate the reading of the results obtained from comparison, we have also defined the following four thresholds for the calculated Hamming distance:

• <0.15 (red): very good match;
• Between 0.15 and 0.3 (yellow): good match;
• 0.3 and 0.45 (green): acceptable match;
• >0.45 (grau): no match.

Values below the specified thresholds are colored as indicated in the list.

13. Results and Discussion

In this section, we present the main results obtained from the analyses described in the previous sections. As mentioned before, six different types of analysis have been carried out.

13.1. Analysis 1: 6G Use Cases vs. Vertical Market Sectors

The different 6G use cases proposed by ITU and the other initiatives have been compared with the vertical market sectors in terms of involved technologies and services/applications. In particular, for each ITU use case, we have calculated the Hamming distance in (1) between its associated binary-valued row in Figure A1 and all the rows corresponding to each vertical market sector in Figure A2. Results are reported in the matrix in Appendix B.1. The matrix entries are colored by the threshold values indicated in the previous list.

From the matrix in Appendix B.1, we have obtained Figure 4 and Figure 5 reporting the total number of times the 6G use cases proposed by ITU and the other initiatives and the vertical market sectors have good/very good or good/very good/acceptable matches, respectively.

When searching from the most impacted vertical market sectors by 6G use cases, from the results in Figure 4, it emerges that e-commerce provides the maximum number of good/very good matches (n. 10 occurrences) between the proposed 6G use cases and the vertical market sectors, while transportation reaches a value of 8. Environment, e-government, and emergency sectors are characterized by a value of 7 occurrences. In terms of the number of good/very good/acceptable matches between the proposed 6G use cases and the vertical market sectors, as shown in Figure 5, the transportation and environment sectors provide the maximum number of these occurrences (19). The eGovernment and eCommerce sectors are characterized by several occurrences equal to 17 and 16, respectively.

13.2. Analysis 2: 6G Use Cases from Other Initiatives vs. ITU 6G Usage Scenarios

With this analysis, we compare the 6G use cases from other initiatives with the ITU 6G usage scenarios. The results of this analysis indicate how the 6G use cases from initiatives are closer to the ITU 6G usage scenarios. Even in this case, for each ITU 6G usage scenario, we have evaluated the Hamming distance (according to (1)) concerning each row in Figure A1, which corresponds to the 6G use cases proposed by the other initiatives. Results are reported in Appendix B.2 with the associated colors. As shown in Figure 6, the best matches in terms of Hamming distance (i.e., $0.00$ value) occur when a fully connected world (HEXA) is compared with ubiquitous connectivity (ITU). Other very good matches are also obtained, for example, if immersive experience (HEXA) and immersive communication (ITU) use cases are compared. In fact, from a technological point of view, these two use cases adopt the same mixed reality (XR) technology to enable human interaction within a virtual environment through 3D images and videos.

Figure 6 gives a graphic representation (in terms of stacked bars) of the variability of the Hamming distance among the 6G use cases proposed by other initiatives compared with the ITU 6G usage scenarios.

In

Table 12. Very good matches obtained from the comparison between the ITU 6G usage scenarios and the other initiatives.

Other 6G Initiatives	ITU 6G Usage Scenarios	Hamming Distance
Fully connected world	Ubiquitous Connectivity	0.00
Immersive experience	Immersive Communication	0.04
Distributed Sensing and Communications	Massive Communication	0.04
Network evolution	AI and Communication	0.04
Distributed Sensing and Communications	Integrated Sensing and Communication	0.08
Network evolution	Ubiquitous Connectivity	0.08

, we extracted the very good matches obtained from the comparison between the ITU 6G usage scenarios and the other initiatives. The fully connected world and ubiquitous connectivity use cases are characterized by the best match (Hamming distance equal to zero). The comparison between the Immersive experience and immersive communication use cases provides a very good match (Hamming distance equal to 0.04), as well as distributed sensing and communications with massive communication, and network evolution with AI and communication. Finally, the comparison between distributed sensing and communications and integrated sensing and communication, as well as network evolution vs. ubiquitous connectivity gives a Hamming distance value equal to 0.08.

As shown, in several comparisons, the use cases proposed by other initiatives are closer to the ITU 6G usage scenarios.

13.3. Analysis 3: Comparison Among All Proposed 6G Use Cases

Following the same approach, we have evaluated the matrix in Appendix B.3 with the results obtained by comparing the 6G use cases to assess their technological similarity. As expected, we have a Hamming distance equal to zero along the main diagonal of the matrix in Appendix B.3. Looking at the rest of the matrix, we observe that the best match in terms of Hamming Distance (namely, it is equal to 0) is obtained if the following cases are compared: (i) immersive experience (HEXA) with immersive communication, and (ii) ubiquitous connectivity (ITU) with the fully connected world (HEXA). Furthermore, it can be observed that the use cases of enhanced communication (from NGA) and immersive communication (from ITU) have a very good match since they rely on the same technologies/applications and services.

Figure 7 shows (through stacked bars) if and how much each proposed 6G use case is close to the other ones in terms of required technologies.

As shown in

Table 13. Very good matches among all 6G use cases.

ITU 6G Usage Scenarios	Other 6G initiatives	Hamming Distance
Immersive Communication	Immersive experience (HEXA)	0.00
Ubiquitous Connectivity	Fully connected world (HEXA)	0.00
AI and Communication	Network evolution (NGMN)	0.04
Massive Communication	Distributed Sensing and Communications (NGA)	0.04
Integrated Sensing and Communication	Distributed Sensing and Communications (NGA)	0.08
Ubiquitous Connectivity	Living and working everywhere (6G IA)	0.08
Ubiquitous Connectivity	Network evolution (NGMN)	0.08
AI and Communication	Ubiquitous Connectivity (ITU)	0.12
AI and Communication	Fully connected world (HEXA)	0.12
Integrated Sensing and Communication	Massive Communication (ITU)	0.12
Integrated Sensing and Communication	Trusted Environments (HEXA)	0.12
Massive Communication	Integrated Sensing and Communication (ITU)	0.12
Ubiquitous Connectivity	AI and Communication (ITU)	0.12
Hyper-Reliable and Low Latency Communication	-	-

, we extracted the very good matches obtained from the comparison of all the 6G use cases.

From the previous table, immersive communication and ubiquitous connectivity usage scenarios from ITU have the best match (Hamming distance equal to zero) with immersive experience and fully connected world use cases from HEXA. Other very good matches are obtained by comparing AI and communication and nassive communication ITU usage scenarios with the distributed sensing and communications use cases from NGMN and NGA, respectively. In this case, the Hamming distance is equal to 0.04. This distance reaches a value of 0.08 in the following comparisons: (i) integrated sensing and communication (ITU) and distributed sensing and communications (NGA), (ii) ubiquitous connectivity (ITU) and living and working everywhere (6G IA), (iii) ubiquitous connectivity (ITU) and network evolution (NGMN). The rest of the very good matches (with Hamming distance equal to 0.12) are obtained when the AI and communication ITU 6G usage scenario is compared with ubiquitous connectivity (ITU) or fully connected world (HEXA) use cases. In addition, the same situation in terms of the Hamming distance value happens when the integrated sensing and communication ITU 6G usage scenario is compared with massive communication (ITU) or trusted environments (HEXA). Finally, the comparison within the ITU 6G usage scenarios gives the same value of Hamming distance (0.12), as in the case of (i) massive communication with integrated sensing and communication, and (ii) ubiquitous connectivity with AI and communication. The Hyper-Reliable and Low-Latency Communication 6G usage scenario proposed by ITU does not provide a very good match with the other 6G use cases. From the results summarized in Table 13, some ITU 6G usage scenarios are very similar in terms of the required technologies.

13.4. Analysis 4: Comparison Among Vertical Market Sectors

With this analysis, vertical market sectors are compared in terms of the involved technological features. The obtained adjacency matrix in Appendix B.4 shows the lowest value (i.e., $0.04$) of the Hamming Distance with regards to the education vs. entertainment markets. This result can be explained by the presence of similar enabling technologies, such as all the HCI devices (e.g., VR/AR/XR, holography, virtual personal assistant). In the other cases, the Hamming distance values vary from $0.08$ to $0.76$.

Figure 8 shows (through stacked bars) if and how much each vertical market sector is close to the other ones in terms of required technologies.

Table 14. Very good matches among all vertical market sectors.

Vertical Market Sectors	Vertical Market Sectors	Hamming Distance
Education	Entertainment	0.04
Automotive	Smart City	0.08
Agriculture	Environment	0.08

summarizes the very good match in terms of the Hamming distance evaluated for each vertical market sector compared with the other ones.

From Table 14, the technological comparison between education and entertainment vertical market sectors provides a Hamming distance of 0.04. In the case of automotive and smart cities, as well as agriculture and environment, this value is 0.08.

13.5. Analysis 5: Technologies vs. 6G Use Cases

In this paragraph, we analyze the percentage of usage of the most relevant technologies in each 6G use case. Results are shown in Appendix B.5. Figure 9 shows which use case can implement the majority of all the most relevant technologies or a subset of them. The values are given in terms of the usage percentage of the most relevant technologies for each proposed 6G use case.

As shown in Figure 9, the enhanced machine communication (NGMN) and Digital Twin (HEXA) use cases implement $92\%$ and $88\%$ of the most relevant technologies, respectively. Smart industry (NGMN) and network-enabled robotic and autonomous (NGA) systems reach values of $84\%$ and $80\%$ in terms of technology percentage usage, respectively. Figure 10 illustrates the percentage of usage of the relevant technologies (or a subset of them) for each 6G use case.

From these results, it can be observed that the narrowband communication technologies and AI/ML are the most used in all proposed 6G use cases, with usage percentages of $92\%$ and $89\%$, respectively. This confirms that in 6G, AI/ML is seen as a basic building block for almost every use case and application. Broadband communications are implemented in $81\%$ of the use cases.

13.6. Analysis 6: Technologies vs. Vertical Market Sectors

With this analysis, we compare one vertical market sector with the other ones to evidence their degree of technological similarity. The results are presented in Appendix B.6. In addition, we have analyzed the percentage of usage of these technologies for each vertical market sector. The results are reported in Figure 11.

It can be observed that the cultural heritage sector tends to be characterized by $96\%$ of the usage of all the technologies, followed by the smart cities sector with $88\%$. These two results are not so surprising due to the large number and heterogeneous applications and services to be provided/implemented for operating in these two market sectors.

In Figure 12, the degree of usage of each specific technology in the vertical market sector is reported.

Even in this case, it can be observed that cloud and AI/ML are pervasive technologies since they are present (i.e., required) in all modern vertical market sectors, i.e., they present a $100\%$ usage percentage, together with enhanced machine communication. The cloud is characterized by an $88\%$ value, while both classical touchscreen/keyboard devices and device status sensors are characterized byan $82\%$ value.

14. Conclusions

ITU and several other initiatives, including operators, suppliers, and stakeholders in the telecommunications sector, have proposed alternative visions of future 6G. The ITU has finalized six usage scenarios that expand those proposed by the ITU itself for 5G. To clarify the overall situation concerning the several proposals, in this paper, we have analyzed the relationships among all the proposed use cases and scenarios (from ITU and other initiatives) so as to evidence their similarities/differences. Comparison has been carried out on an objective reference basis that considers the main technological features, applications, and services required to define/implement the use cases and to describe the scenarios. We have demonstrated that many use cases proposed by ITU and other initiatives can be considered almost identical at least from the technological point of view. As an example, this is the case of immersive communication (ITU) and immersive experience (HEXA-X), distributed sensing and communications (NGA) and massive communication (ITU), fully connected world (HEXA-X) and ubiquitous connectivity (ITU). We have also compared the selected vertical market sectors in terms of the involved technologies.

As final considerations, from the analysis presented in this paper, it also emerges that ITU covers in practice all the scenarios of the other 6G initiatives and meets all the requirements of the considered vertical market sectors. In this sense, the scenarios specified within ITU can be considered complete. This fact is important because ITU actively collaborates with 3GPP in the research on and definition of all the technical aspects of 6G, i.e., the integrated network architecture, the advanced radio interfaces, the communication protocols and procedures, etc. The 3GPP standardization activities are typically driven by the use cases and the ITU ones that can be safely taken as reference by 3GPP since, as shown in this paper, they also represent/include the visions of the other initiatives and stakeholders that are active in the telecommunication sector. Industries, telcos, and research entities only focus on a group of scenarios that can be traced back to those proposed by the ITU, at least from the technological point of view. Finally, the results in this paper also confirm that advanced AI/ML techniques are used in every scenario/use case, and vertical market sectors are now considered a necessity.

Future research areas include the network capabilities, such as the implementation of advanced AI/ML techniques, the integration of sensors and NTNs within the 6G framework, and the disaggregated and distributed Radio Access Network (RAN). To provide potential advancements in specific technologies or new use cases that could emerge as 6G develops, future works will regard (i) the identification of common words and tags, (ii) KPIs defined by each research and industrial initiative, (iii) composition and mixing of several use cases, and (iv) a more detailed analysis of the potential market impact of each use case. The economic projections or scenarios, together with the market forecast, will be included in future works.