# 6G-BRICKS: Developing a Modern Experimentation Facility for Validation, Testing and Showcasing of 6G Breakthrough Technologies and Devices

Ioannis P. Chochliouros, John Vardakas, Kostas Ramantas, Sofie Pollin, Sylvie Mayrargue, Adlen Ksentini, Walter Nitzold, Md Arifur Rahman, Jimmy O'meara, Ashima Chawla, et al.

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## To cite this version:

Ioannis P. Chochliouros, John Vardakas, Kostas Ramantas, Sofie Pollin, Sylvie Mayrargue, et al. 6G-BRICKS: Developing a Modern Experimentation Facility for Validation, Testing and Showcasing of 6G Breakthrough Technologies and Devices. 19th IFIP International Conference on Artificial Intelligence Applications and Innovations (AIAI), Jun 2023, León, Spain. pp.17-31, 10.1007/978-3-031-34171-7_1. [hal-05411470](https://hal-inriaHalId:hal-05411470)

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# 6G-BRICKS: Developing a Modern Experimentation Facility for Validation, Testing and Showcasing of 6G Breakthrough Technologies and Devices

Ioannis P. Chochliouros<fnref n="1" />(✉), John Vardakas<fnref n="2" />, Kostas Ramantas<fnref n="2" />, Sofie Pollin<fnref n="3" />, Sylvie Mayrargue<fnref n="4" />, Adlen Ksentini⁵, Walter Nitzold<fnref n="6" />, Md Arifur Rahman⁷, Jimmy O'Meara<fnref n="8" />, Ashima Chawla<fnref n="8" />, Dimitrios Kritharidis<fnref n="9" />, Vasileios Theodorou<fnref n="9" />, Shuaib Siddiqui<fnref n="10" />, Francisco Ibañez<fnref n="11" />, Georgios Gardikis<fnref n="12" />, Dimitris Diagourtas<fnref n="13" />, Loizos Christofi<fnref n="14" />, Alain Mourad<fnref n="15" />, Didier Nicholson¹⁶, Alexandros Kostopoulos<fnref n="1" />, Anastasia S. Spiliopoulou<fnref n="1" />, and Christos Verikoukis<fnref n="17" />

**Abstract.** Shifting towards 5G/6G implicates for a great diversity of challenges for the involved markets, especially via the creation of vast amounts of generated data and of related novel applications serving a great multiplicity of verticals. Such innovative services exceed the capabilities of existing 5G infrastructures for potential support of their corresponding KPIs and computational offloading, thus creating a new generation of Smart Networks. Towards fulfilling this target, the 6G-BRICKS project aims to deliver a new 6G experimentation facility building on the baseline of mature platforms coming from ongoing EU-funded activities and bringing breakthrough cell-free (CF) and RIS technologies. We have presented the essential architectural structure of the above facility and assessed in detail the core objectives of the project, as these “identify” diverse technical challenges and

<footnote n="1">¹ Hellenic Telecommunications Organization (OTE) S.A., 99 Kifissias Avenue, 15124 Maroussi-Athens, Greece
ichochliouros@oteresearch.gr</footnote>

<footnote n="2">² Iquadrat Informatica SL, Barcelona, Spain</footnote>

<footnote n="3">³ Katholieke Universiteit Leuven, Leuven, Belgium</footnote>

<footnote n="4">⁴ Commissariat à L'Energie Atomique et aux Energies Alternatives, Paris, France
⁵ EURECOM, Biot, France</footnote>

<footnote n="6">⁶ National Instruments Dresden GmbH, Dresden, Germany
⁷ IS-Wireless, Piaseczno, Poland</footnote>

<footnote n="8">⁸ L.M. Ericsson Limited, Dublin, Ireland</footnote>

<footnote n="9">⁹ Intracom S.A. Telecom Solutions, Peania, Greece</footnote>

<footnote n="10">¹⁰ Fundació Privada i2CAT, Barcelona, Spain</footnote>

<footnote n="11">¹¹ Brainstorm Multimedia SL, Valencia, Spain</footnote>

<footnote n="12">¹² Space Hellas S.A., Athens, Greece</footnote>

<footnote n="13">¹³ Satways Ltd., Iraklio-Athens, Greece</footnote>

<footnote n="14">¹⁴ eBOS Technologies Limited, Nicosia, Cyprus</footnote>

<footnote n="15">¹⁵ InterDigital R&D France, Cesson-Cévigné, France
¹⁶ Ektacom, Les Ulis, France</footnote>

<footnote n="17">¹⁷ Industrial Systems Institute (ISI) / Athena Research Center, Athens, Greece</footnote>
dedicated areas for future research. In addition, we have discussed and evaluated
the fundamental use cases together with their intended PoCs that are expected to
demonstrate strong market impact.

**Keywords:** 5G · 6G · Artificial Intelligence (AI) · Cell-Free (CF) · CFmMIMO · Edge continuum · eXplainable AI (XAI) · Industry 4.0 · Machine Learning (ML) · MIMO · Metaverse · mmWave · O-RAN · Reconfigurable Intelligent Surfaces (RIS) · xApp · Zero-Touch service management

# 1 Introduction

Commercial deployments of 5G are now progressing worldwide, delivering new capa-
bilities, improved performance and new applications for customers. For Mobile Network
Operators (MNOs), a set of figures that are 5G-supported, including network slicing,
disaggregation, and cloud-native design [1], are enabling the use of new applications
and new business models [2]. The gradual shift to the full digitization of the real world
is expected to create vast amounts of generated data and applications, like immersive
communication, and holographic telepresence, while social experiences powered by
Extended Reality (XR) will become our default way of communication in the near
future. These emerging applications exceed the current and future capabilities of 5G
networks, both in terms of Key Performance Indicators (KPIs) that must be supported
and in terms of their requirements on an ultra-dense computational infrastructure, to sup-
port the required degree of computational offloading [3]. Thus, academia and industry
have “shifted” their attention to the investigation of a new generation of Smart Networks
capable of supporting such performance. The first results of these studies show that 6G
networks will deliver efficiency clearly superior to 5G and satisfy evolving services and
applications [4, 5] making them a key enabler for the intelligent digital society of 2030
[6].

More specifically, 5G kick-started a trend towards software-defined infrastructures (SDI) and Software Networks that replace “black boxes” (e.g., physical network functions, such as firewalls) with their softwarized equivalents, deployed at standards-based “Whitebox” Servers. This trend has gradually propagated to the RAN (Radio Access Network) via the O-RAN (Open-RAN) initiative [7] that delivers software implementations of the CU (Centralized Unit) and DU (Distributed Unit) components, while Software-Defined Radios (SDRs) allow softwarization principles to reach down to the low-PHY (Physical layer). While softwarization and open APIs (Application Programming Interfaces) have been adopted with the objective of promoting interoperability and reducing OPEX (Operating Expenses) and CAPEX (Capital Expenditure), they have also revolutionized experimentation platforms and testbeds. Open Source software [8] stacks and Common Off-the-Shelf (COTS) hardware can be leveraged to affordably build and scale-up testbeds that allow customization and experimentation on every aspect of 5G and Beyond (B5G) infrastructures. Still, the enormous complexity of the 5G standards and software stacks makes end-to-end (E2E) experimentation platforms
extremely challenging to deploy, requiring interdisciplinary efforts and big investments
in integration.

The 6G-BRICKS project [9] will deliver this vision, bringing together specialists that work on breakthrough 6G technologies from all architecture tiers, namely Cell-Free (CF) networking [10–12] and Reconfigurable Intelligent Surfaces (RIS) [13]. These technologies will be integrated in reusable, self-contained testbed nodes, to be deployed at two E2E 6G testbed sites (i.e.: Katholieke Universiteit Leuven (KU-L) in Belgium and Eurecom (EUR) / CEA-LETI in France). These will be federated under a common set of Experimentation Tools, deployed under a common Cloud node, offered by ATHENA/ISI in Greece.

## 2 6G-BRICKS: Essential Scope and Core Objectives

6G-BRICKS will be the first open 6G platform that combines cell-free, Open Air Interface (OAI) [14] and RIS, while adopting the proven principles of softwareization, open Interfaces (O-RAN), and Open Source software stacks, putting future expansion and evolvability at its core. However, experience from past 5G-PPP efforts [15] has shown that the enormous complexity of the standards and software stacks makes evolvability and scaling-out efforts extremely challenging, requiring interdisciplinary efforts and big investments in integration, by the involved market “actors”. To this very challenging end, 6G-BRICKS intends to deliver the first open and programmable O-RAN Radio Unit (RU) for 6G networks, termed as the OpenRU, based on an NI USRP-based platform [16]. Further on, among the project’s target is also to integrate the RIS concept into the OAI. The scheduled effort will lead to breakthrough experimentation tools, going well beyond the current Testing as-a-Service (TaaS) capabilities [17] of current initiatives and allowing experiments also on devices via O-RAN compliant xAPPS<fnref n="1" />. Thus, 6G-BRICKS aims to deliver a new 6G experimentation facility, building on the baseline of mature ICT-52 platforms [18], that bring breakthrough cell-free and RIS technologies, which have shown promise for growth in beyond 5G networks. Moreover, novel unified control paradigms based on Explainable AI (Artificial Intelligence) and Machine Reasoning are to be explored in detail. In our intended approach, all corresponding enablers will be delivered in the form of reusable components with open APIs, termed as “bricks”. Initial integrations with O-RAN will also be performed, aiming for the future-proofing and interoperability of 6G-BRICKS outcomes.

6G-BRICKS’ aim is so to offer a trusted, agile and evolvable 6G experimentation facility, effectively federating two experimentation platforms (one in Belgium and one in France) from previous 5G-PPP initiatives under a “Core Site” (in Greece) acting as the facility entry point and offering Public Cloud and experimentation services. This facility is expected to be accessible by third-party consortia, vertical application owners and experimenters from the vertical and component industry. It will showcase a

<footnote n="1">¹ An xApp is a software tool used by a RAN Intelligent Controller (RIC) to manage network functions in near-real time. The xApps are part of a RIC which is a central software component of the Open RAN architecture, being responsible for controlling and optimizing RAN functions and resources. These applications – or services –include functions like radio resource management, mobility management and security.</footnote>
disaggregated Management Plane and Operations Support System (OSS) to support extendibility, evolvability and multi-tenancy, beyond centralized Cross-Domain Service Orchestrators (CDSOs) [19] and OSS / BSS systems, as in current 5G-PPP experimentation platforms. The corresponding 6G experimentation facility is shown in Fig. 1 and includes the following architectural tiers:

<figure><img src="image_4.png" /><figcaption>Fig. 1. 6G-BRICKS experimentation facility - General architecture.</figcaption></figure>

**Core Tier:** It acts as the entry point to the facility, offering public cloud services to the 6G sites. Mature front-end elements and experimentation engine will be leveraged and deployed at the Core Site from the 5G MediaHUB project [20], delivering DevOps Driven Testing as-a-Service functionality allowing, in turn, test cases and validation testing workflows to be authored via standard DevOps tools. A unique testing tool based on Near-RT (Real-Time) RIC (RAN Intelligent Controller) are to be delivered giving experimenters access to low-level RRM (Radio Resources Management) and RAN slicing capabilities [21] via standardized xApps. In addition the Core Site will offer Business Support System (BSS) services to the 6G-BRICKS facility, allowing vertical application owners to upload their applications and Business Intents [22] (Service Level Objectives - SLOs).

**A disaggregated Management Plane:** It consists of a set of Domain Manager Orchestrators (DMOs) for each Cloud, Edge, and Network orchestration domain. The DMO
layer, deployed at each facility sites, acts as a unified controllability framework aiming to provide the ability to enforce and propagate state-to-action mappings, automatically generating service objectives based on the SLOs (or business intents) submitted at the Business Layer. These actions are subsequently implemented by the infrastructure domain (e.g., RAN controller, SDN, VIM (Virtual Infrastructure Manager), etc.). Explainable AI (XAI) mechanisms [23] are leveraged for policy translation and unification. This breakthrough explainable architecture design supports end-to-end slicing [21], provides explainable feedback to experimenters for potential SLA (Service Level Agreement) breaches and facilitates a loose coupling with the Business Layer, avoiding bottlenecks.

**The 6G Experimentation Platforms layer:** Here, breakthrough 6G technologies are integrated in reusable, self-contained modules with O-RAN interfaces to ensure the openness and reusability of the developed components. At the KU-L site, a Distributed CF RAN is delivered, leveraging on the MARSAL [24] baseline work and also an O-RAN stack. The EUR site builds on the 5G-EVE [25] facility and the EUR OAI O-RAN stack, which will be integrated with a RIS platform from the RISE-6G project [26]. In both sites, UE (User Equipment) Farms will be deployed, i.e., a managed constellation of UE devices to be offered to experimenters, supporting virtualization and service placement at the device level, termed as the Deep Edge [27]. The UE farm may include: (i) 5G enabled remotely controlled smartphone devices, or; (ii) similarly specified clusters of Single Board Computers (e.g. Raspberry Pis) and Internet of Things (IoT) devices.

The project is structured around fulfilling several explicit objectives, all fully aligned to its novel strategic vision. These fundamental objectives are listed and briefly discussed/assessed as follows:

**Objective 1:** *Delivering an evolvable 6G experimentation facility that will integrate breakthrough 6G technologies and will efficiently "federate" two well-established experimentation platforms – testbeds, under a common set of experimentation tools.* The intended scope will be about: (i) Delivering an open Experimentation and Business Support layer with DevOps-driven testing and Zero-Touch service management capabilities [28], thus unlocking access to the facility for vertical owners and experimenters, and; (ii) supporting a managed UE farm layer, thus "pushing" computation down to the device tier.

**Objective 2:** *Validate and showcase advanced use cases in holographic communication, metaverse and digital twinning, showcasing the benefits of 6G breakthrough technologies and architectures.* Intended targeted actions will be about: (i) Demonstrating the technological feasibility of “better than 5G” KPIs in terms of capacity, reliability, location accuracy and energy efficiency; (ii) evaluating the effect of Network KPIs and Edge Continuum deployments [29] on extreme 6G Service KPIs [30], thus identifying bottlenecks and trade-offs, and; (iii) validating a set of Key Value Indicators (KVIs) [31], jointly defined with four ongoing ICT-52 baseline projects (i.e.: MARSAL [24], REINDEER [32], RISE-6G [26] and HEXA-X [33]).

**Objective 3:** *Support fully disaggregated and software-defined infrastructures (SDIs) [34], adopting virtualization, Software-Defined Radio (SDR) and O-RAN interfaces to promote modularity and reusability of developed components.* Intended targeted actions
will be about: (i) Delivering open and reusable components (“bricks”) for all technological domains, including USRP-based OpenRUs [16], O-RAN compliant CUs, DUs, as well as RIC and open DMO and PaaS (Platform as-a-Service) abstraction frameworks; (ii) offering programmable infrastructures at the compute domain and at the network domain, where physical resources (e.g., UEs) and virtual resources (e.g., slices, etc.) can be shared by multiple tenants/experimenters; (iii) hosting third party experiments and vertical applications, coming from corresponding future Open Calls, and; (iv) supporting RAN slicing and RRM down to the RU level, allowing low-level control from experimenters via xAPPs.

**Objective 4:** Offer a fully decentralized management plane, supporting zero-touch orchestration of compute and communication resources based on XAI [23]. Intended targeted actions will be about: (i) Defining and delivering a scalable architecture of DMOs, disaggregating the CDSOs of the State-of-the-Art (SoTA) facilities; (ii) implementing a Zero-touch policy engine that benefits from XAI and Machine Reasoning (MR) methods [35]; (iii) defining a XAI and MR for root cause analysis at DMO level, and; (iv) defining both XAI and MR to help experimenters to debug the tests run on 6G-BRICKS (including RAN and Cloud Edge Continuum platforms) and find solutions.

**Objective 5:** Offer a Compute Continuum abstraction framework supporting a disaggregated wireless Xhaul. Intended targeted actions will be about: (i) Delivering an interoperable continuum of solutions, comprising of Cloud, Edge and Far Edge/IoT device levels [36] as well as the disaggregated wireless X-HAUL systems [37] that link them (Fronthaul, Midhaul, Backhaul); (ii) offering a PaaS abstraction framework, exposing infrastructure resources via common and open APIs, following the Composable Infrastructures paradigm<fnref n="2" />; (iii) delivering Multi-agent Deep Reinforcement Learning (DRL) [27, 38] agents, driving automatic adaptations and joint optimizations to the end-to-end provisioning and connectivity layer to fluctuating user demand.

**Objective 6:** Deliver breakthrough technologies towards a 6G RAN via Distributed Cell-Free and RIS. Intended targeted actions will be about: (i) Integrating for the first time RIS and gNB (mmWave) to demonstrate and experiment with RIS technology using E2E service; (ii) devising and implementing a novel RIS controller to dynamically update RIS reflector configuration to support UE mobility; (iii) devising and implementing novel ML-based RIS control algorithms that predict user position and optimal RIS configuration; (iv) designing novel CF algorithms that distribute the computations in an optimal way (according to the respective use case); (v) implementing selected algorithms as software “Bricks”; (vi) designing novel multi-band algorithms that maximally exploit information gathered in different frequency bands; (vii) implementing a selection of these as software “Bricks”; (viii) designing and implementing novel Over-The-Air (OTA) synchronization algorithms [39] that minimize the signalling overhead while satisfying the stringent synchronization requirements for CFmMIMO (CF massive multiple Input Multiple Output) [40].

<footnote n="2">² Composable infrastructure is a framework that decouples device resources in order to treat them as services. Physical compute, storage and network fabrics are examples of device resources that can be treated as services.</footnote>
**Objective 7:** Provide a secure and trusted Experimentation Facility for multiple concurrent tenants and experimentation platforms. To this aim, specific targeted actions will be about: (i) Supporting zero-trust establishment via the Software Defined Perimeter (SDP) paradigm [41]; (ii) offering VPN (Virtual Private Network) as-a-Service [42] for simplifying the establishment towards cross-site VPN encrypted tunnels, and ensuring future expansion towards experimentation sites outside the GEANT network; (iii) delivering a Security Orchestrator (SO) for the overall management of the security policies and configurations of the facility.

**Objective 8:** Maximise the impact expected to be created by the project to a great number of potential “actors”/recipients through wide means of dissemination, communication, standardisation and exploitation activities.

# 3 Use Cases

The 6G-BRICKS project is structured around two selected use cases (UCs) that are further to be developed, as discussed below. The former examines metaverse as an “enabler” of a modern workplace while the latter aims to focus on 6G Applications for serving Industry 4.0. Moreover, 6G-BRICKS intends to proceed to dedicated Proofs-of Concept (PoCs) for each separate UC so that not only to extend any corresponding market impact but also to increase adaptability in real scenarios of use and assess Business viability, especially in verticals. These UCs are briefly discussed in the following sections.

## 3.1 Use Case 1: Metaverse as an Enabler of a Modern Workplace

The Metaverse [43–45] is one of the emerging use cases, which is expected to “drive” the transition to B5G systems, as it requires KPI improvements by at least an order of magnitude. The Metaverse leverages of the latest advances in Extended Reality (XR) / Virtual Reality (VR) technologies to support social interactions in virtual spaces; this trend is well aligned with the ongoing digitalization of our societies and the digital transformation of businesses that place more and more emphasis on remote collaboration [46]. In this context, videoconferencing is a “key aspect” of the digital transformation, and disruptive technologies can make it even more compelling, helping mitigate limitations in terms of social interaction. Untethered VR [47] is already at the limit of 5G network capabilities, requiring extremely high downlink capacity (>100Mbps per device), and low latency (<5ms), to achieve impressiveness. The Metaverse further “pushes” the limits, allowing users to interact in 360 XR environments [48], while freely navigating in a Virtual Environment (VE). Recent advancements in the volumetric video domain allow to capture the user’s volume in real time and insert the resulting hologram into these VEs, enabling multiple users to be co-present, together with others, in a 3D space while embodied in the own self-representation.

This UC will demonstrate how network densification via distributed cell-free can make untethered Metaverse UCs a reality, offering acceptable quality of experience, and the ability of immersive social interactions (cf. Figure 2). Both scenarios adopt the Multi-point Control Unit (MCU) element [49], that is the application which handles
the real-time processing of “holograms” (i.e., the 3D representation of users), ensuring synchronization aspects and state consistency of the VE, and streaming a 360 VR Sphere of the VE to each participant. The MCU receives and transmits multiple MPEG (Moving Pictures Experts Group) 3D video streams with the volumetric videos. The (timestamped) incoming videos are decoded, processed accordingly, and converted into a fused volumetric video for the scene, thus providing a single stream to the client devices. This brings together specialists on breakthrough 6G technologies, such as cell-free networking, distributed processing and RIS, as well as adopting principles of modularity and softwareisation to deliver the first truly modular E2E 6G experimentation platform in Europe. 6G-BRICKS focuses upon structuring the various architecture tiers around the concept of “LEGO Bricks”, delivering self-contained testbed nodes that can be reused across testbed infrastructures. This significantly lowers the barrier of entry to an E2E experimentation platform for specialists to bring their breakthrough technologies for validation and experimentation.

<figure><img src="image_5.png" /><figcaption>**Fig. 2.** 6G-BRICKS Use Case 1.</figcaption></figure>

A first PoC will demonstrate an evolutionary “holoconference” scenario in a virtual meeting room, showcasing ultrahigh-speed with low-latency communication (uHSLLC) [50] that is made possible with distributed CF technologies. Holoconferencing is a special case of Social Virtual Reality (VR) platforms, where users can meet and cooperate with others, normally represented as virtual avatars, in a 3D environment [51]. This scenario will leverage on an innovative volumetric capture technique that uses conventional (and thus lower cost) cameras, hence promoting adoption by a wider audience. The Metaverse attendees will be represented by their avatars around a semicircular virtual meeting table.

A second PoC will deal with virtual team Building activities and will demonstrate a revolutionary scenario, showcasing ultrahigh data density (uHDD) communications and Joint Communication and Sensing enablers [52]. A much more advanced Volumetric Capture technology based on RGBD (Red-Green-Blue-Depth) cameras [53] will be offered, resulting in volumetric videos that involve point clouds, hence requiring much higher bandwidths in the uplink (UL) direction. Moreover, participants will be free to roam in a 3D environment, while interacting with their peers and completing a “team
building” activity or puzzle, such as the very popular escape room challenge. In this scenario the VE is much larger and involves multiple 360 spheres (one per participant).

## 3.2 Use Case 2: 6G Applications for Industry 4.0

This UC aims to focus upon Industry 4.0 applications [54–56] and demonstrate how 6G enablers [57, 58] can contribute towards more efficient operators, leveraging autonomous robots, digital twinning and XR. Autonomous driving [59] and Digital Twins (DT) [60] are a rapidly growing market [61], particularly suitable for industrial applications [62] (cf. Figure 3). Yet, its actual impact to the operations heavily relies on the collection of high-volume data with low latency, which is something 6G can offer.

<figure><img src="image_6.png" /><figcaption>Fig. 3. 6G-BRICKS Use Case 2.</figcaption></figure>

For the case of DT [63–65] a Tbps-level transmission rate is often required to meet the requirements on data volume for precise modeling, simulation and verification. Through fast iterative optimization and decision-making, digital entities can also be generated in centralized or distributed mode as required [66]. Security and privacy are also an important requirement; towards this, 6G networks also contribute [67] by supporting data storage, collection, processing, training, and modeling in both centralized and distributed architectures. Meanwhile, NGMN [68] considers autonomous robots [69, 70] and enhanced Machine Communication as one of the key 6G use-cases, reflecting the growth in collaborative robotics, and autonomous machines. The requirements concern mainly the extreme low-latency communications and high reliability to synchronize robots among them and with the remote controller. This UC is intended to be examined and validated via two dedicated PoCs, as briefly described below.

The PoC of this use case will show how 6G will support autonomous robots for industry 4.0 [71]. Autonomous robots are machines that can manage their tasks without the assistance of a human operator [72, 73]. They efficiently perform repetitive and complex tasks while requiring little to no downtime, which is ideal for continuous production. Autonomous robots help prevent human injury in the factory by holding and moving
heavy items on the production line [74–76]. In addition, they can quickly analyze and choose the most efficient route to “pick and deliver” items in the factory based on incoming requests. The autonomous robot will move in the factory while having low-latency communication. It will move objects from position “A” to “B” according to the received request from a server.

The second PoC will show how 6G supports remote DT visualization through an Augmented Reality (AR) interface [77–79] by superposing SCADA data on the real object. This PoC will exploit AR to enable an inspection feature for discovering malfunctioning elements in indoor Oil and Gas systems [80, 81]. Potential malfunctions will be identified by close virtual inspection via the combination of several techniques [82]. Apart from being considerably flexible, virtual inspection is the most intuitive, straightforward and economical method for assessing the conditions of an industrial machinery.

# 4 Discussion

The 6G-BRICKS project brings together specialists on breakthrough 6G technologies, such as cell-free networking, distributed processing and RIS, as well as adopting principles of modularity and softwarisation to deliver the first truly modular E2E 6G experimentation platform in Europe. 6G-BRICKS focuses upon structuring the various architecture tiers around the concept of “LEGO Bricks”, delivering self-contained testbed nodes that can be reused across testbed infrastructures. This significantly lowers the barrier of entry to an E2E experimentation platform for specialists to bring their breakthrough technologies for validation and experimentation.

In particular, the corresponding project platform and the related facilities will be used for validation testing and showcasing of the clear benefits and capabilities of 6G breakthrough technologies and devices. The 6G-BRICKS experimentation facility aims to serve a “dual role, “that is both as a playground for testing advanced vertical applications and for validation testing and showcasing of the clear benefits and capabilities of 6G breakthrough technologies and devices. Moreover, the scope is about delivering and testing new architecture principles, with multi-tenancy, disaggregated Operations Support Systems (OSS) and Deep Edge integration at the forefront.

In the present paper we have briefly presented the essential architecture of the intended experimentation facility and discussed its essential architectural tiers. As a step further we have not only discussed but in fact extended the 6G-BRICKS fundamental objectives, strongly affecting all potential dimensions of the expected technical progress of the project. These objectives practically “delineate” the forthcoming research and testing effort around several thematic domains (mainly CF and RIS), towards proposing innovative and fully validated 6G-oriented solutions.

Then we have presented the fundamental use cases that are to be deployed and evaluated during the course of the project. The first one is about the consideration and the effective inclusion of the Metaverse context as a practical enabler for realizing a modern workplace where we intend to demonstrate an evolutionary “holoconference” scenario in a virtual meeting room showcasing uHSLLC as well as distinct virtual team building activities, showcasing uHDD communications and sensing. The second UC
is about the use of 6G applications in Industry 4.0 and is to be assed via two PoCs examining the inclusion of autonomous robots for the support of industrial processes and the development of digital twin visualization through an AR interface to allow inspection in indoor Oil and Gas systems.

**Acknowledgments.** This work has been performed in the scope of the 6G-BRICKS European Research Project and has been supported by the Commission of the European Communities /HORIZON, Grant Agreement No.101096954.

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