6G Perspective of Mobile Network Operators, Manufacturers, and Verticals

The first release of 5G technology is being rolled out worldwide. In parallel, 3GPP is constantly adding new features to upcoming releases covering well-known use cases. This raises the questions i) when will 6G be introduced?, ii) how can 6G be motivated for the stakeholders, and iii) what are the 6G use cases? In this letter, we present the perspective of these stakeholders, namely the network operators, manufacturers, and verticals, identifying potential 5G shortcomings and the remaining 6G solution space. We will highlight the Metaverse as the enabler for 6G addressing omnipresent daily challenges and the upcoming energy problem.


I. INTRODUCTION
P UBLIC 5G mobile communication systems are currently being rolled out.Most of the 5G communication systems in operation are based on Release 15 non-standalone (NSA) and are nowadays converted into standalone (SA) systems.While NSA is still based on a 4G core system, the SA embeds a 5G core and can therefore be considered the first natural 5G system.While 4G and its predecessors still had the consumer market in mind, 5G aims to open up entirely new markets.Even though 5G is advertised with high data rates to attract the old consumer customer front, the absolute novelty in 5G is the support of low latency communication for the Industrial Internet, healthcare, mobility, etc., mainly machine-to-machine Paul Schwenteck is with the Deutsche Telekom Chair of Communication Networks, TU Dresden, 01187 Dresden, Germany (e-mail: Paul.Schwenteck@ tu-dresden.de).
Giang T. Nguyen is with the Haptic Communication Systems, TU Dresden, 01187 Dresden, Germany, and also with the Centre for Tactile Internet with Human-in the-Loop, 01069 Dresden, Germany (e-mail: Giang.Nguyen@ tu-dresden.de).
Holger Boche is with the Chair of Theoretical Information Technology, TU Munich, 80333 Munich, Germany (e-mail: holger.boche@tum.de).
Frank H. P. Fitzek is with the Deutsche Telekom Chair of Communication Networks, TU Dresden, 01187 Dresden, Germany, and also with the Centre for Tactile Internet with Human-in-the-Loop, 01069 Dresden, Germany (e-mail: Frank.Fitzek@tu-dresden.de).
Digital Object Identifier 10.1109/LNET.2023.3266863communication.This led to a new customer base, namely the verticals.In addition to latency, 5G has brought two further groundbreaking changes.Firstly, new communication architectures such as non-public or 3D networks are supported parallel to the public cellular networks.Secondly, in-network concepts from the Internet Engineering Task Force (IETF), mainly for the Internet, have been intensively incorporated into mobile communication systems.The latter increased the importance of software in communication systems.Initially, only the backbone communication components have been realized by software rather than proprietary hardware boxes.Nowadays, even Radio Access Networks (RAN) technologies are candidates for softwarization.Even though most people or industry sectors have yet to experience the full 5G technology, researchers are starting to think about 6G technologies [1].Unfortunately, a clear definition of 6G communication networks has not been defined yet.European flagship research projects such as HEXA-X [2] or the 6G Platform Germany [3] have gathered leading industry players and research institutions to develop such definition.
Often, researchers advertise 6G technologies without considering the upcoming releases of the 3rd Generation Partnership Project (3GPP).This often leads to a misunderstanding in the community about what 6G is.Release 16 and 17 will complete Release 15, initializing the first wave of lifelike 5G technology enabling most of the envisioned use cases, especially those addressing low latency requirements such as machineto-machine communication, e.g., with mobile robotics.The second wave starts with Release 18 (5G advanced starting standardizations in 2022).Currently, Release 19 is looking for new topics to be discussed in standardization.
Therefore, in this letter, we will first briefly list in Section II the features that will be available in the upcoming 5G releases.Then, in Section III, we will look at the current needs of the verticals and whether the current releases meet these.From the shortcomings of the current releases and the new needs of the verticals and consumers due to the recent results, we present possible use cases of 6G in Section IV. 6G can only succeed if we build a communications system that serves the needs of people or people-owned machines.Along the way, we will examine what new opportunities are available to the manufacturers and what role the network operators play in this.

II. WHAT WILL 5G GIVE US?
To understand what 6G should focus on, a short description of the feature and study list in 3GPP for ongoing 5G activities is given.It is assumed that 6G will be introduced with Release 21 or higher.However, an earlier version can also be called

III. CURRENT NEEDS OF THE VERTICALS FOR 6G
To discover which areas to improve with 6G, we first need to consider which vertical needs are already covered by 5G.At the same time, we have to take into account what manufacturers can provide and what network operators are willing to invest.In addition to the old consumer-customer front, the verticals play an increasingly important role.Especially in machine-to-machine communication, verticals emerge as customers.Low latency, which 5G already achieves, plays a significant role here.The new network architectures provided by 5G also enable the verticals to implement their own use cases.In general, it can be said that the current 5G applications meet most of the needs of the verticals.
Manufacturers sell 5G legacy solutions to ensure the network operates appropriately for the customer.This includes providing low latency, high throughput, and adequate scalability.In addition, support is provided by the network operators.However, medium-sized companies usually need help to afford these costs, and it is not profitable for manufacturers to build such small networks.Furthermore, the sovereignty of these networks is a point of contention, as the technology is sold in black boxes.
Contradictory, 5G cheap low-end solutions are affordable and based on an open-source implementation.OpenRan but also OpenCore implementations are already available.However, these usually require constant support, as current networks still need to be stable [4].In addition, the entire setup has to be done by the user.Performing all the steps yourself requires a detailed understanding of the underlying code, especially on the RAN side.Thus, verticals remain dependent on the expertise of network operators.

IV. 6G USE CASES
From the current needs of the verticals, we can derive some use cases for 6G.At the same time, new needs are created by current events that 5G does not yet cover.On the one hand, we can use 6G to build on and improve existing 5G architectures and use cases.On the other hand, 6G will form the basis for satisfying the new needs of the verticals and consumers.

A. Towards 6G Private Networks -Getting Down the Costs and Complexity
As mentioned in the previous section, private networks are essential for the industry.However, 5G has yet to offer an affordable solution for medium-sized companies and, at the same time, configurable by the end user.Interfaces would allow end users to configure their private network according to their needs.This way, verticals do not have to pay external network operators to set up their network, which saves costs and human resources.Another point of improvement in private networks is the security and sovereignty of the built-in hardware and software.The Bundesamt für Sicherheit in der Informationstechnik (BSI) is currently establishing guidelines that will allow customers in Germany and later throughout Europe, to verify the supply chain of their ordered components.This verification, named IT-Grundschutz [5], will also help manufacturers to verify their manufactured goods.The Groupe Speciale Mobile Association (GSMA) also provides Network Equipment Security Assurance Schemes (NESAS) that enable manufacturers to test their products more effectively and automatically against security standards [6].These test schemes also increase transparency for the verticals and network operators that buy the products.Affordable, easy-toconfigure, and secure private networks for verticals would be the key selling factor for verticals.However, there is no reason not to include these improvements to private networks in a later 5G release.

B. The Metaverse -The Enabler for 6G Use Cases
Society has faced several significant challenges in recent years, such as the global pandemic, the still persistent shortage of skilled workers, and the aging society and, thus, the more critical need for caregivers.Each of these challenges brings its problems, but we see a common denominator that can help all three: bring humans in the loop by connecting them and their capabilities more closely.The Metaverse would be able to address many of these issues (s.Fig. 1) while connecting almost all technologies and use cases of 6G together in a single killer application.In 2023 the revenue in the Metaverse market is projected to reach US$54.95bn and by the annual Authorized licensed use limited to the terms of the applicable license agreement with IEEE.Restrictions apply.
growth rate of 36.71%, the project market volume will reach US$490.40bnby 2030 [7].5G could be able to build the foundation for the Metaverse in Release 19.Still, to implement all the use cases in the Metaverse, new technologies are needed that 6G can provide.
Quarantine during COVID-19 has created new needs among end users for more immersive communication between each other, which includes a better auditory and visual representation of the counterpart and the ability to transmit touches, smells, or even tastes.New network architectures are needed to capture all the required data from the five senses of humans.This requires new sensors and actuators from the manufacturers and new multi-model codecs for the different requirements of haptic and smell-based communication.
A new network architecture in 6G could be Body Area Network that can link different human body parts and analyze specific data.Molecular communication [8], [9], another new technology in 6G, can be used to transmit data about the human body or send information about smells and tastes directly to the sensor.The new sensors and body area networks allow us to digitize and store people's skills.Through the Metaverse, we can train other humans with digital information.Humans can absorb the knowledge and learn the skills with the teacher's direct influence.This would not only be a solution to shortage in skills as there are more humans with the required skills then, but also we can transfer knowledge quickly and effectively on a global scale.To handle the amount of information and at the same time guarantee the required latency, we need to compute the data much closer to the user.Multi-Access Edge Computing (MEC) can be the solution here [10], [11].
However, through the Metaverse and the Tactile Internet, we can not only connect humans with humans but also humans with machines [12].In the healthcare sector, it would be possible for doctors to perform interventions remotely in rural areas.Security and resilience are vital for a smooth process of such delicate operations.6G with quantum communication can secure this communication by exchanging unbreakable keys between two parties using quantum entanglement [13], [14].The vulnerability against denial-of-service (DOS) attacks of quantum key distribution (QKD) is described in [15].Additionally, quantum communication can reduce latency even further for applications in the Metaverse.
In addition, we can use the Metaverse to support the care sector.Sensors in clothing or pacemakers, for example, can be used in conjunction with molecular communication to read out medical data and inform the patient and doctor in advance of any abnormalities.Together with location-independent medical care, disorders can be treated remotely, thus reducing the need for nursing staff.Robots with sensors and actuators can also assist in the home and thus advance home automation.

C. Tackle the Energy Problem -The Hidden Obstacle for 6G
Suppose we strengthen the digital cohesion of people and distribute the skills globally in the Metaverse.In that case, people are no longer forced to travel long distances.Each person's ecological footprint can thus be improved and thus counteract global warming.However, the Metaverse itself will generate an enormous amount of data that must be transmitted and stored.The influx of information comes from measuring all human senses and from recording people's skills.Both will enormously increase energy consumption, which we cannot afford due to the climate change.In addition, network operators must be able to transmit these amounts of data without the networks collapsing.To convey human senses over a communication network with priorities, network slicing and Time-Sensitive Networking (TSN) are vital enablers.Also Artificial Intelligence (AI) shows its effectiveness in managing and orchestrating cellular network resources [16].AI will become just as important, if not more so, in 6G as data volumes increase and network resources become an even more scarce resource [17].
Additionally, new technologies in 6G are needed to achieve an overall positive energy balance.To accomplish this, Post-Shannon, Joint Sensing and Communication, and quantum approaches will reduce the information exchange dramatically, enable cost and energy-efficient human-machine interaction, and enable secure and low-latency communication, respectively.Here we explain the basic idea behind the novel approaches and refer the interested reader to the appropriate literature: i.) Post-Shannon communication already shows how the required traffic can be reduced enormously, especially in Digital-Twins applications [18], [19].Completely new goal-oriented communication tasks are implemented in the Post Shannon Communication based on new coding schemes.Compared to Shannon's message transmission task, they achieve much higher spectral efficiency and lower transmission latency.Several interesting transmission tasks support even secrecy for free [20].Other novel decoding algorithms such as Guessing Random Additive Noise Decoding (GRAND) can also help to reduce energy consumption and the amount of data transmitted [21]; ii.)In addition to the data transmission, we must ensure that the data can be stored.Digitizing skills will generate massive data, whereas conventional storage media can become too expensive.DNA-based storage could offer a solution here, as it provides enormous capacity [22].Such storage solution should be used to store, e.g., training data, which are not needed that often nor need to be read out quickly; iii.)Joint sensing and communication is already seen as a possible feature of 6G.Combining radar sensing and communication would help applications such as autonomous driving, traffic monitoring, robotics, and drone control [23], [24].The customer will save hardware and energy costs if a component can perform both sensing and communication tasks; iv.)Quantum communication [13], [14] in public communication networks will use quantum randomness, entanglement and teleportation to increase the security and efficiency of 6G communication networks.
In Table I, we have contrasted the cost of energy consumed with gains in latency and security.In addition, we have indicated when we can expect the release of the technologies.Only by effectively integrating all technologies into the Metaverse can we meet desired needs while reducing energy consumption.The optimization of digital twin representations concerning communication-and computing complexity is here of particular importance [18], [19], [25].

V. CONCLUSION
In this letter, we have looked at the areas in which we need 6G at all.To do this, we first summarized what 5G will offer us in current and future versions.Then we looked at the current needs of the verticals and whether they are already being met by 5G.Especially in the area of private networks, for machine-to-machine communication, there still needs to be a cost-effective and easy-to-configure solution.Enabling verticals to configure their networks independently would make them independent of network operators and thus save costs and personnel.If 5G does not find a solution in later releases, 6G can start here.
However, we see innovations and use cases for 6G in the Metaverse, which is becoming increasingly important due to current situations such as the pandemic and shortage of skilled workers.New technologies are needed to ensure extreme

Manuscript received 15
March 2023; accepted 10 April 2023.Date of publication 13 April 2023; date of current version 25 September 2023.This work was supported in part by the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft) as part of Germany's Excellence Strategy -EXC 2050/1 -Cluster of Excellence "Centre for Tactile Internet with Human-inthe-Loop" (CeTI) of Technische Universität Dresden under Grant 390696704, and in part by the Federal Ministry of Education and Research of Germany in the Programme of "Souverän.Digital.Vernetzt."-Joint Project 6G-Life under Grant 16KISK001K and Grant 16KISK002.The associate editor coordinating the review of this article and approving it for publication was P. Monti (Corresponding author: Paul Schwenteck.)
6G if the marketing departments of the companies want to outbid each other.3GPP Feature and Study Item list (Rel-19:) Integrated Sensing and Communication; Metaverse; Network Sharing; AI/ML Model Transfer; Robots; Energy considerations We shall not forget the discussion and standardization of non-public networks, which drive the establishment of local 5G campus networks, support the market entry of fundamentally new operators, and will lead to new ways of thinking for 6G.
This work is licensed under a Creative Commons Attribution 4.0 License.For more information, see https://creativecommons.org/licenses/by/4.0/Authorized licensed use limited to the terms of the applicable license agreement with IEEE.Restrictions apply.• 3GPP Feature and Study Item list (Rel-15-17): Study on Communication for Automation in Vertical Domains; New radio, Non-Orthogonal Multiple Access; Satellite; TLS; Edge computing; network slicing; • 3GPP Feature and Study Item list (Rel-18): Satellite; IoT; UAV; Sidelink; Proximity; Location and Positioning; Smart Energy; Ad hoc Group communication; Enhanced Network Slicing; eXtended, augmented, and virtual reality; Railways; Tactile and multi modality communication services; Self-organising Networks; •