Network Architecture in the 6G/IOWN Era: Inclusive Core

Satoru Furukawa, Tomonori Takeda, and Arifumi Matsumoto

Abstract

In the era of the 6th-generation mobile communication system (6G) and Innovative Optical and Wireless Network (IOWN), it is assumed that four facets of convergence and coordination, namely, cyber space and physical space, computing and network, analog and digital, and mobile communication and fixed communication, will advance as communication services or the environment changes. This multifaceted convergence and coordination increases the need for end-to-end and seamless coordination of information processing and distribution across terminals, devices, networks, and applications. In this article, we introduce our research and development efforts in a network architecture for the 6G/IOWN era called the Inclusive Core, which is the foundation platform for achieving this multifaceted convergence and coordination.

Keywords: network service, IOWN, fixed-mobile convergence

1. Network evolution toward 6G

Mobile communication services have been developing generation by generation, starting from voice call to data communication services and multimedia communication services. They have been playing key roles in our daily lives and various industries. With features such as enhanced data speeds, low latency, and massive connectivity, the 5th-generation mobile communication system (5G) is expected not only to upgrade existing multimedia communication services but also to provide new values as a foundation for future industries and society, together with artificial intelligence (AI) and Internet of Things.

As a cyber-physical system (CPS) where cyberspace and physical space interact, 6G is expected to enable high-capacity and low-latency transmission and reception of real-world video and sensing information as well as feedback (actuation) to the real world by transmitting control signals with high reliability and deterministic delay. It is also envisioned that AI will be integrated into communication services and solve various problems by recognizing real-world human actions and events in cyberspace and be able to communicate on behalf of humans [1, 2]. In these services, communication between cyberspace and physical space in a CPS corresponds to the nerves in the human body that transmit information between the brain and each organ. A huge amount of information (perceptual information and movement instructions) will be collected via communication for AI in a CPS to make decisions. Therefore, it will be necessary to transmit and exchange large amounts of information at high speed and low latency.

To continuously meet the evolution of such services and social demands, services using 6G/Innovative Optical and Wireless Network (IOWN) networks are necessary to respond to the progress of multifaceted convergence and coordination inside and outside the network (Fig. 1). First, convergence and coordination of cyberspace and physical space links digitalized space/world, such as cyberspace and physical space/world, to achieve services represented by a CPS. Second, networks are expected to provide information processing (computing) as one of their functions and to mediate and support information processing at terminals and servers, thus efficiently enabling end-to-end services. It is therefore necessary to promote the convergence of computing and networking that will streamline and accelerate information processing and information exchange. Third, 6G is expected to bring about a variety of wireless accesses such as satellite, undersea, and private radio access network (RAN), in addition to conventional public RAN. Fixed accesses using the IOWN optical communication infrastructure are also expected to expand. It is therefore required to achieve full-fledged convergence of fixed and mobile access, which enables users to adaptively use various types of mobile and fixed accesses and experience common services with certain functions and quality guarantee regardless of the type of access. Finally, to accurately and quickly map all physical spatial information into cyberspace, convergence and coordination of digital and analog is also envisioned, in which non-packetized digital and analog signals are communicated via networks to enable information exchange using various data and communication formats.

Fig. 1. Progress toward convergence and coordination.

To achieve such convergence and coordination, NTT laboratories are promoting research and development of the Inclusive Core as a network architecture for the 6G/IOWN era.

2. Inclusive Core architecture

Since launching 4G services, networks have been virtualized and software-enabled through network function virtualization (NFV)^*1, and general-purpose servers and shared servers are being used to reduce costs and improve efficiency of operations. Typical examples include vEPC (virtualized Evolved Packet Core) and vIMS (virtualized IP Multimedia Subsystem). In addition, 5G uses an architecture that is based on cloud technology, and 5G core networks deploy cloud-native network function (CNF)^*2. By multi-access edge computing (MEC)^*3, server applications that process information can be deployed near the edge—the entrance to the communication network—without going through the Internet. This enables the provision of services using applications requiring low latency.

Virtualization and cloud technologies are commonly used as the foundation for NFV and MEC, and due to the commonality of technologies, specifications and technologies are expected to be common, and computing infrastructure will be commonly deployed and built across NFV and MEC. With the future deployment of virtualized RAN (vRAN), which is the virtualization of RAN, virtualization and cloud technologies are expected to be applied to devices closer to the terminal. Due to technological commonality, applications are expected to be deployed not only at the edge of the network but also over a wide area including RAN, sharing computing infrastructure resources. Finally, a network is expected to evolve into an environment where computing resources are ubiquitous throughout the entire network [3, 4] (Fig. 2).

Fig. 2. Evolution toward 6G.

The Inclusive Core provides computing services by mixing and tightly coordinating network functions and application functions on such a ubiquitous computing infrastructure in the network. These computing services combine distributed computing resources of not only computing functions of terminals but also computing functions in the cloud and network and integrate the information processing and communication functions required for user services (Fig. 3). This constitutes a distributed application including computing functions in the network and enables the use of enhanced services, regardless of location and usage mode (terminal), which require advanced communication functions in coordination with functions and processing on the service (server) side and on the user (terminal) side.

Fig. 3. Inclusive Core architecture.

Communication between the terminal and server in the cloud and information-conversion processing for communication traditionally occur and cause delays. In contrast, when server applications on terminals and clouds are integrated and aggregated in a specific computing infrastructure in the network, communication between terminals and clouds as well as information processing for communication are no longer necessary, and real-time coordination is possible. Functions to terminate access lines, such as mobile and fixed, are traditionally provided separately. In contrast, by integrating and deploying multiple functions for terminating various access lines, such as mobile and fixed, and information processing applications on the same computing platform, it is possible to seamlessly continue services regardless of communication lines.

*1	NFV: A technology that converts network functions conventionally achieved using dedicated hardware into software and runs them on a general-purpose server.
*2	CNF: Technology to run network functions on containers.
*3	MEC: A mechanism for deploying computing functions near the edge, the entrance to a communication network.

3. Inclusive Core technologies

3.1 In-network Service Acceleration Platform

The In-network Service Acceleration Platform (ISAP) coordinates the advanced computing functions of information processing applications distributed throughout the network and achieves higher performance and lower latency processing. By taking over some of the application functions of the terminal and cloud and by closely coordinating and connecting with the communication functions of the network, information and processing of terminals and services that are currently separated by the network can be directly coordinated to optimize processing, and optimal allocation of computing resources including accelerators can be achieved. We aim to achieve end-to-end information exchange with ultra-high speed and low latency.

3.2 Fault detection and visualization for system resilience

In telecommunication network services, large-scale outages have recently occurred, and their impact on the use of various services have become a social problem. Mission-critical services are expected to be increasingly provided in mobile and fixed networks, so it is extremely important to build a robust communication network. Large-scale and long-time outages are often caused by control-plane behavior, and to address this, it is important to strengthen the control plane for 6G and have early detection and recovery methods for problems. Therefore, we aim to develop (1) a method for making the control plane robust to avoid failures and complexity and (2) mechanism to further visualize the root cause of failures and detect signs of failures.

More details about the ISAP and fault detection and visualization for system resilience are introduced in the article “In-network Service Acceleration Platform (ISAP)” [5] in this issue.

3.3 Self-sovereign identity information distribution

In the 6G era, the convergence of cyberspace and physical space will provide a wider variety of services in cyberspace than before, and user data including sensitive privacy information (identity information) will be handled in cyberspace. An identity information distribution mechanism is thus required, with which user identity information is protected, and only the minimum necessary information is exchanged to trusted parties. It is also necessary to verify the authenticity of the data to be exchanged and verity the other party with whom the data are exchanged, rather than implicitly accepting. We aim to develop a self-sovereign identity (SSI) information distribution mechanism (SSI infrastructure) to ensure user privacy and provide services using users’ sensitive information.

More details of the SSI infrastructure are introduced in the article “Self-sovereign Identity (SSI) Infrastructure for Reliable Identity Data Distribution in the 6G/IOWN Era” [6] in this issue.

3.4 Cooperative Infrastructure Platform

As an early form of the Inclusive Core, we are researching and developing the Cooperative Infrastructure Platform. This platform aims to promote social implementation of mission-critical CPS services by integrating and coordinating cyberspace and physical space. The requirements for CPS services are very different from those of conventional web applications, and the infrastructure for CPS services is designed to support a wide variety of components (sensors, actuators, etc.), stable information distribution between cyberspace and physical space, and various functions to enable flexible control in accordance with use cases.

More details of the Cooperative Infrastructure Platform and related technologies are introduced in the article “Cooperative Infrastructure Platform to Accommodate Mission-critical CPS Services” [7] in this issue.

Figure 4 shows an example use case of the Inclusive Core. Computing resources including a graphics processing unit (GPU) within the ISAP are allocated as a virtual terminal for each user, then high-resolution three-dimensional (3D) video rendering is executed on this virtual terminal. Finally, the result is transmitted as uncompressed video. The terminal only displays the video, indicating that even a low-end terminal without a GPU or other computing resources can display and edit high-resolution 3D video, as long as the transmitted video can be displayed and an operation user interface be provided at a terminal.

Fig. 4. Inclusive Core use case example.

4. Future developments

This article introduced the concept, architecture, and technologies of the Inclusive Core, which will enable new services through multifaceted convergence and coordination in 6G/IOWN. While 5G is being used in a wide variety of industries, organizations and companies worldwide are studying 6G, and international standardization organizations such as 3GPP (3rd Generation Partnership Project) are planning to create specifications, including the definition of 6G. We will promote research and development through discussions with many stakeholders for a broad consensus in the industry on the Inclusive Core architecture. Some of the technologies introduced in this article are under experiment and trials, and we will promote research and development for their social implementation.

References

[1]	Next G Alliance, “Digital World Experiences,” Dec. 2022. https://www.nextgalliance.org/white_papers/digital-world-experiences/
[2]	Hexa-X, “Deliverable D1.1: 6G Vision, Use Cases and Key Societal Values,” Feb. 2021. https://hexa-x.eu/wp-content/uploads/2021/02/Hexa-X_D1.1.pdf
[3]	Beyond 5G Promotion Consortium White Paper Subcommittee, “Beyond 5G White Paper Version 2.0,” Mar. 2023. https://b5g.jp/doc/whitepaper_en_2-0.pdf
[4]	NTT DOCOMO, “DOCOMO 6G White Paper,” https://www.docomo.ne.jp/english/corporate/technology/whitepaper_6g/
[5]	K. Hayashi, S. Hirai, T. Matsukawa, and H. Baba, “In-network Service Acceleration Platform (ISAP),” NTT Technical Review, Vol. 22, No. 12, pp. 26–32, Dec. 2024. https://ntt-review.jp/archive/ntttechnical.php?contents=ntr202412fa2.html
[6]	A. Matsumoto and N. Higo, “Self-sovereign Identity (SSI) Infrastructure for Reliable Identity Data Distribution in the 6G/IOWN Era,” NTT Technical Review, Vol. 22, No. 12, pp. 33–39, Dec. 2024. https://ntt-review.jp/archive/ntttechnical.php?contents=ntr202412fa3.html
[7]	N. Azuma, K. Ono, T. Tsubaki, T. Kawano, T. Tojo, and T. Kuwahara, “Cooperative Infrastructure Platform to Accommodate Mission-critical CPS Services,” NTT Technical Review, Vol. 22, No. 12, pp. 40–46, Dec. 2024. https://ntt-review.jp/archive/ntttechnical.php?contents=ntr202412fa4.html

	Satoru Furukawa Senior Manager, Vice President, Network Architecture Project, NTT Network Service Systems Laboratories. He received a B.E. and M.E. in chemical system engineering from the University of Tokyo in 1997 and 1999. He joined NTT the same year and has been engaged in research and development on architecture and systems of network services.
	Tomonori Takeda Senior Research Engineer, Supervisor, Network Architecture Project, NTT Network Service Systems Laboratories. He received a B.E and M.E. in electronics, information, and communication engineering from Waseda University, Tokyo, in 1999 and 2001. He joined NTT the same year and has been engaged in research and development on the next-generation transport network architecture and next-generation mobile network architecture.
	Arifumi Matsumoto Senior Research Engineer, Supervisor, Network Architecture Project, NTT Network Service Systems Laboratories. He received a B.S. and M.S. in information and computer science from Kyoto University in 2002 and 2004. He joined NTT in 2004, where he has been engaged in designing the architecture, engineering, and standardization of IP network and researching quality-of-experience control technologies for video-streaming services. He developed a machine-learning-based infrastructure inspection system with Japan Infra Waymark Corporation. He is currently leading the development and demonstration of digital identity and network service coordination technologies at NTT Network Service Systems Laboratories.

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