September 2025 Vol. 23 No. 9

Front-line Researchers

• Ryuichiro Higashinaka, Visiting Senior Distinguished Researcher, NTT Human Informatics Laboratories

  

  Abstract
  Regarding communication between people, when people share “common ground”—such as common topics, prerequisites, and perceptions—they can understand each other and engage in communication. If we could build common ground between computers and people, communication between them would become smoother. The concept of common ground has been around for a long time; however, many of its facets remain unexplained. By unraveling these facets individually, it will be possible to implement the process of building common ground. Ryuichiro Higashinaka, a visiting senior distinguished researcher at NTT Human Informatics Laboratories, is attempting to elucidate common ground by using generative artificial intelligence and other techniques to enable communication between computers and humans. We spoke with him about his approach to tackling “old-yet-new” problems and his belief that “it wasn’t a failure, but rather the effort was simply not successful.”

Rising Researchers

• Hirofumi Sasaki, Distinguished Researcher, NTT Network Innovation Laboratories

  

  Abstract
  With the advancement from fifth-generation mobile communication systems (5G) to 6G and the spread of various services such as artificial intelligence, augmented reality, and virtual reality, wireless communication systems in the 2030s will need to have even greater data capacity. In preparation for this future explosive increase in demand for wireless communications, NTT has been independently researching and developing “OAM-MIMO multiplexing transmission”—which combines orbital angular momentum (OAM) multiplexing transmission technology and multiple-input multiple-output (MIMO) technology—in a manner that will enable us to build a wireless communication system with a higher capacity than ever before. We spoke with Hirofumi Sasaki, a distinguished researcher at NTT Network Innovation Laboratories and a leader in the field of OAM-MIMO multiplexing transmission technology, about what enables terabit-class wireless transmission.

Feature Articles: Keynote Speeches and R&D on Access Networks Presented at Tsukuba Forum 2025

• Creating Value That Transforms the World: Access Networks to Support a Sustainable Society

  

  Abstract
  NTT Access Network Service Systems Laboratories (AS Lab) conducts research and development on access networks across five key domains: optical-fiber access technology, infrastructure technology, access system technology, wireless access technology, and operation technology. With the aim of achieving new value creation and contributing to global sustainability, AS Lab is promoting research to accelerate the implementation of IOWN (the Innovative Optical and Wireless Network) and 6G (sixth-generation mobile communication systems). This includes efforts to support service diversification, smart operations, and the development of new business domains. This article introduces AS Lab’s latest technologies in these areas.

• Looking Ahead to the Next Five Years

  

  Abstract
  Since the announcement of the Innovative Optical and Wireless Network (IOWN) concept five years ago, the All-Photonics Network (APN) has been commercialized, and IOWN optical computing is being presented at the Expo 2025 Osaka, Kansai, Japan. This article looks back at the progress made to date and introduces the creation of new value and evolution of technologies toward the further development of IOWN. The content of this article is based on a keynote speech delivered by Katsuhiko Kawazoe, former NTT representative member of the board and senior executive vice president (currently chief executive fellow), at Tsukuba Forum 2025 held on May 15th−16th, 2025.

• Research and Development of Operational Technologies Using AI for Network Robustness and Business Automation

  

  Abstract
  NTT Access Network Service Systems Laboratories is promoting research and development of future technologies for network operations and other general operations. In this article, we introduce our research and development efforts in the areas of zero-touch operation technologies that enable accurate and quick network management without human intervention, technologies that extend the scope of operations automation, and technologies that support human work to lower required skills and improve safety, with the aim of making networks more robust.

• Towards New Era of Social-infrastructure Maintenance and Management: Revolution through AI Leveraging and Infrastructure Sharing

  

  Abstract
  NTT Access Network Service Systems Laboratories is conducting research and development to solve issues in social infrastructure, such as improving maintenance and management efficiency, enhancing resilience, and reducing environmental impact, aiming for a sustainable society. We, the Civil Engineering Project of NTT Access Network Service Systems Laboratories, aim to innovate infrastructure maintenance and management by advancing the use of artificial intelligence (AI) and incorporating the concept of sharing facilities and data. This article presents our new technologies from the following two perspectives: AI leveraging and sharing in social infrastructure.

• R&D toward Operational Innovation and New Value Creation of Social Infrastructures

  

  Abstract
  Aiming at operational innovation through digital transformation of access network system business, we at the Access Network Management Project of NTT Access Network Service Systems Laboratories are researching and developing smart engineering (design/construction) and smart maintenance (maintenance/operation) technologies. We are also taking on the challenge of creating new value in fields other than communications by using the assets of communication facilities. The technologies developed for these communication infrastructures will be applied to other infrastructures such as electricity, gas, and water, and will contribute to the maintenance and management of social infrastructures of Japan and address social issues.

Regular Articles

• Compositional Abilities Emerge Multiplicatively: Exploring Diffusion Models on a Synthetic Task

  

  Abstract
  Modern generative models exhibit remarkable abilities to produce realistic data. However, for practical use, they must reliably compose new combinations of concepts to generate outputs unseen during training, reflecting real-world compositionality. Prior research shows that diffusion models exhibit intriguing yet inconsistent compositional generalization abilities in text-to-image generation tasks. Motivated by these findings, we conduct a controlled study to investigate compositional generalization in diffusion models using synthetic tasks. By systematically varying training data attributes, we measured models’ capacities to generate out-of-distribution samples. Our results reveal three key insights: (i) compositional ability emerges according to the underlying data-generation structure; (ii) compositional-task performance shows sudden “emergence” due to multiplicative dependencies on constituent tasks, clarifying emergent behaviors in generative models; (iii) generating out-of-distribution samples from rarely encountered concept combinations requires significantly more optimization steps compared with generating familiar combinations. Our findings establish a data-centric framework for understanding emergent compositional capabilities in generative models.

• Optical-fiber Cables for On-road Surface Wiring without Using Poles and Conduits

  

  Abstract
  The NTT Group is investigating further coverage expansion of optical-fiber networks for 5G (fifth-generation mobile communications network) base-station demand and popularization of Internet-of-things devices. NTT has thus developed an on-road surface-wiring optical-cable technology that does not depend on utility poles or underground conduits, which has been essential for optical-cable installation. It also allows for optical-fiber cables to be laid without the need for large-scale construction such as road excavation. This article gives an overview of this technology, which enables road-surface wiring by installing optical-fiber cables in grooves formed on asphalt pavement.

Global Standardization Activities

• Report on the 37th APT Standardization Program Forum (ASTAP-37)

  

  Abstract
  The 37th Asia-Pacific Telecommunity Standardization Program (ASTAP-37) was held 21−25 April 2025 in Bangkok, Thailand in-person format (hybrid participation was prepared for industry workshop and opening/closing plenary). One hundred thirty-seven experts from 19 countries, including 35 online participants, participated in ASTAP-37. The industry workshop was also held to share emerging topics. This article reports the outline of ASTAP-37.

External Awards

• External Awards