A broad view of the future of communications, from fine devices for terahertz wave to space communications--NTT R&D FORUM 2024

NTT held the NTT R&D FORUM 2024 at its Musashino Research and Development Center from November 25 to 29, 2024, to introduce the technologies of the NTT Group. FORUM 2024" was held at the Musashino Research and Development Center from November 25 to 29, 2024. Among the many exhibits, the following photos give an overview of the exhibits that are worth paying attention to in order to get a glimpse of the future of wireless communications.

Changing the world of "Tsunagu

Dielectric image line multi-sector antenna

The antenna is a planar multi-sector antenna that covers 360 degrees with 12 elements, each element covering about 30 degrees. 360 degrees coverage allows a single antenna to cover an entire room by placing it on the ceiling in the center of the room. The directional nature of the antenna makes it easier to install than existing antennas that must be placed in the four corners of a room. In addition, the thinner design makes it possible to place the antennas in a landscape-friendly manner.

Distributed antenna system utilizing analog RoF

A distributed antenna system that enables 6G carriers to provide high-capacity communications infrastructure. Antenna functions are distributed to a central station and multiple dispatch stations, which are connected by IWON's analog RoF (Radio-over-Fiber) using optical fiber. While coaxial fiber could not transmit radio frequency signals over long distances due to high energy loss, analog RoF can extend the distance to several kilometers.

The tensioning station consists of only an antenna, amplifier, and photoelectric converter, and can be miniaturized to the size of a palm and placed without spoiling the landscape. simulations of distributed antenna systems combining multiple frequency bands, such as Sub6, millimeter wave, midband, and subterahertz, have shown that uplink throughputs of several tens of Gbps in the uplink and 100s of Gbps in the downlink for terminal throughput.

5G Evolution & 6G Communication Technology Pioneering Efforts

NTT DOCOMO exhibited its efforts toward 6G, which it aims to commercialize in 2030. 6G promotion values include "Sustainability," "Efficiency," "Customer Experience," "NW for AI," and "Anywhere Connectivity Network. Discussions on 6G standardization are expected to get underway in earnest at Rel-21, where discussions will begin in 2026 at 3GPP.

The photo shows an exhibit of an AI-based wireless interface demonstration experiment. In a joint experiment with Docomo, NTT, Nokia, and SK Telecom, it was confirmed that communication speed could be improved by up to 18% by applying AI-based optimal modulation scheme design to the wireless interface.

This is the Digital Trial exhibit, where base station antennas, physical space, and mobile station antennas can be digitized to simulate their behavior in order to build a digital twin for the 6G era. Real-time throughput of 6G communications can be simulated in real time as users walk around the premises of Ericsson's headquarters in Sweden. The technology holds promise as a means of making invisible radio waves visible.

Undersea wireless network with undersea acoustic communication

The exhibit featured technology to realize communication using sound waves on the seafloor, where communication by radio waves is difficult. The exhibits showed that the company has developed a technology to increase the speed to over 1 Mbps using ultrasonic waves, whereas conventional acoustic communications could only communicate at low speeds of several tens of kbps. The technology is designed to meet the needs for communication with underwater divers and remote control of underwater devices from land. The company aims to provide a two-way communication service for divers using voice, etc. by around 2027, and a communication service for underwater construction and equipment inspection using video, etc. by around 2030.

Sub-terahertz band device technology for 6G

The exhibit featured device technology for high-frequency bandwidths for 6G: sub-THz wave communication from 100G to 300GHz, which is envisioned to be used for ultra-high-speed wireless communication between base stations and cloud sensing. For the practical application of sub-THz waves, development of device technology and propagation control technology is underway. As for device technology, we have developed an ultra-compact device that condenses sub-THz wave communication functions from the size of a conventional lunch box to less than the size of a grain of rice. As a result, the communication module has also been reduced to a few centimeters square and the size of the palm of one's hand.

RIS (Reconfigurable Intelligent Surface) is exhibited as a propagation control technology. RIS (Reconfigurable Intelligent Surface) is a metasurface that periodically arranges unit structures that are small in relation to the wavelength, enabling directional control and focusing of radio waves. A prototype of a metasurface with a static structure was exhibited, and by magnifying it with a microscope, the microstructure, including transistors, could be confirmed. As for the active RIS, a model was exhibited, and it was explained that development will continue and experiments will be conducted in early 2025.

Creating New Experiences

Motor ability transfer technology: brainwave assisted exercise

Technology to support activities without physical movement, using brain waves to determine movement, was exhibited. In the demonstration, a cap-shaped sensor was attached to measure brain waves. The system determines the user's intention to move the right hand or left hand, and moves the wheelchair in the virtual space to the right or left. In the photo, Takehiro Nakamura, CSO of NTT Docomo, is wearing the device. In the future, by increasing the resolution from two movements of the right and left hands to the movement of each finger, etc., the company hopes to expand the range of application of EEG-based motion support and link it to human augmentation.

Photoelectric Fusion Devices (PEC)

He presented the status of research and development of devices that enable optical communications to be used over short distances. The NTT Group calls this "Photonics Electronics Convergence" (PEC) and has a roadmap from PEC-1, which links data centers, to PEC-2, which links boards in data center racks, to PEC-3, which links semiconductor packages within boards, to PEC-4, which is used within semiconductor packages. PEC-1 has already been commercialized, and PEC-2 aims to be commercialized in 2025.

In addition, PEC-3, which connects semiconductor packages, exhibited an evaluation version of the Membrane Optical Transmitter Module, which integrates 16 membrane lasers and waveguides in a 1.11mm x 2.75mm size, and will continue to be developed for social implementation in 2028.

IOWN Intercountry Metaverse Experience Using APN/DCI Technology

Using IOWN's All Photonics Network (APN), the demonstration connected Japan and Taiwan for real-time communication within a virtual reality (VR) space. In Taiwan, employees of Chunghwa Telecom responded and shared the same metaverse space with the Japanese participants, demonstrating that a distance of 3,000 km can be connected with a delay of 17 ms to provide a delay-free metaverse experience. In fact, the performance was equivalent to having the servers located in a single data center, despite the distributed server configuration, with the video distribution and real-time AI translation servers located in Taiwan and the image rendering servers in Japan. This is an indication that IOWN can dramatically increase the degree of freedom in server and data center placement.

Remote production using IOWN

A remote production demonstration was given, showing how video production can be decentralized by utilizing IOWN APN. Video from six cameras installed at Saitama Stadium (actually, pre-recorded camera video was distributed in real time) was transmitted via IOWN, and editing such as camera switches and inserts of tickers was performed at the Musashino Research and Development Center, the venue of the R&D Forum. Current video production requires production at the relay site, but IOWN makes it possible to separate the relay site from the production site for greater efficiency.

Expanding the realm of communications from Earth to space

Realization of the Space Integrated Computing Network Concept

NTT Group named the project NTT C89 (CONSTELLATION 89), which aims to build facilities for space utilization as the 89th constellation following the 88 constellations (CONSTELLATION) in the entire sky. It will contribute to the promotion of Japan's space industry. The overall vision of the project is the realization of a space integrated computing network, and envisions a future that integrates the use of various satellites and other space applications from terrestrial and undersea networks.

HAPS technology for extending through-core coverage

A model of HAPS (High Altitude Platform Station) flying in the stratosphere to expand mobile network coverage was exhibited, and the status of research and development, including promotion of early practical application and further advancement of direct communication systems using HAPS, was explained.

Optical Satellite Communication Technology

Optical data relay service was introduced as one of the initiatives of SPACE COMPASS, a company jointly launched by NTT and SKY Perfect JSAT. In the future, many observation satellites using Low Orbit Satellite (LEO, Low Orbit Satellite) will be shared, and a variety of data will be collected, from natural disasters to CO2 emissions monitoring and smart agriculture.

On the other hand, LEOs moving at high speed relative to the ground can only communicate continuously for about 10 minutes from a specific point on the ground. This makes it difficult to transmit large amounts of accumulated data directly to the ground, and other means are required. The optical data relay service uploads data from a low earth orbit satellite to a geostationary orbit satellite (GEO, Geostationary Orbit Satellite) at an altitude of 36,000 km above the ground at a high speed of 10 Gbps, and downloads the data via optical and wireless connections between the geostationary satellite and the ground, The exhibit proposed and exhibited a solution to the problem of data downloading.

New wireless energy transmission technology

Exhibited research on wireless power transmission using lunar sand as a transmission line to transmit power to a lunar rover. It is difficult to lay electric wires to provide power to a lunar rover for moving on the surface of the Moon. To solve this problem, they developed a technology to transmit power to the rover by using sand on the Moon as a dielectric and applying voltage to the sand to generate power waves. The rover can run on the far side of the Moon, where sunlight cannot reach and solar power cannot be generated. In a demonstration, a large crowd gathered to see the rover's wheels move when it was placed close to sand that imitated the surface of the moon.