June 2025 Vol. 23 No. 6

Front-line Researchers

• Sousuke Imamura, Senior Distinguished Researcher, NTT Space Environment and Energy Laboratories

  

  Abstract
  In September 2021, NTT formulated a new environment and energy vision called “NTT Green Innovation toward 2040” and announced that “NTT Group aims to achieve carbon neutrality by 2040.” This new environment and energy vision—as well as the “2050 Carbon Neutral Declaration” announced by the Japanese government in October 2020 and carbon-neutrality-targeting initiatives by Japanese companies—all focus on the use of renewable energy and energy conservation as their main strategies. In addition to these initiatives to drastically reduce emissions of greenhouse gases such as carbon dioxide (CO₂), other initiatives take an approach that involves absorbing and using the CO₂ that is emitted. We spoke with Dr. Sousuke Imamura, a senior distinguished researcher at NTT Space Environment and Energy Laboratories, about one such initiative to reduce marine CO₂ by applying breeding technologies to algae, fish, and shellfish.

Rising Researchers

• Yusuke Ijima, Distinguished Researcher, NTT Human Informatics Laboratories

  

  Abstract
  Speech-synthesis technology improves accessibility for people with disabilities and the elderly and supports peoples’ daily lives in applications such as call centers and car-navigation systems. It is currently being used in applications such as automatically generating narration, game-character voices, and voices in multiple languages while preserving the tone of voice. Speech-synthesis technology can be used not only for creating voice actors and celebrity voices but also to restore the voices of people who have lost their voice for some reason, if audio or video of them is available. It can thus greatly contribute to society, but challenges in making synthesized speech sound more natural remain. We spoke with Distinguished Researcher Yusuke Ijima, who developed the latest speech-synthesis technology, “zero/few-shot cross-lingual speech synthesis.”

Feature Articles: Research and Development for NTT C89: NTT Group’s Space Business

• Improving Mobile Communication Service Quality Using Non-terrestrial Networks

  

  Abstract
  At NTT, we aim to achieve ultra-wide coverage for mobile communication services using non-terrestrial networks (NTNs) in the era of Beyond fifth-generation mobile communication system (5G)/6G. This article introduces our efforts to provide customers with high-quality mobile communication services that meet the required conditions for throughput, latency, etc., even when using NTNs.

• AI Inference Technology toward a Space Datacenter

  

  Abstract
  With recent advancements in space development, the number of satellites has increased, and the use of artificial intelligence (AI) inference technology is drawing attention, particularly in Earth observation and communications. The NTT Group is aiming to build a new space infrastructure using geostationary orbit (GEO) satellites and exploring data relay and data storage via GEO satellites. This article presents concrete approaches to improving data analysis efficiency, such as event-driven AI and change detection technologies, which are essential for such use cases.

• Power Transmission Technology Using Electric Field Surface Waves—Future Energy Infrastructure Expanding into Space

  

  Abstract
  Power transmission technology using electric field surface waves excited by electric field resonance can deliver power by using a variety of surrounding substances instead of cables, which makes for flexible application. This article describes the basic principle of this technology and its envisioned use on the lunar surface.

Global Standardization Activities

• Report on World Telecommunication Standardization Assembly (WTSA-24)

  

  Abstract
  The World Telecommunication Standardization Assembly 2024 (WTSA-24) was held in New Delhi, India from October 15 to 24, 2024. The WTSA is the most important assembly of the International Telecommunication Union - Telecommunication Standardization Sector (ITU-T), headed by Seizo Onoe, Director of the ITU Telecommunication Standardization Bureau, and is held every four years. This article provides an overview of WTSA-24 and introduces the main discussion topics.

External Awards

• External Awards