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7 February 2023

Docomo leads in new materials and haptic platforms on path to 6G

New materials will be as important to next generation connected experiences as new network technologies, enabling a new generation of devices and equipment that could fulfil the ‘metaverse’ dream of absolutely ubiquitous connectivity and AI-based responsesiveness.

The Japanese mobile ecosystem is often in the forefront of developments that borrow from materials science as well as radio engineering. Kyocera and NEC, for instance, have been pioneers in Reconfigurable Intelligent Surfaces (RIS – see below), and now the country’s largest mobile operator, NTT Docomo, has revealed a project related to windows that do not obstruct radio waves.

The operator is working with window glass specialist YKK AP on a light, porous aerogel material that would allow radio waves to penetrate more easily than current windows, because it has a dielectric constant close to that of air.

Buildings with these windows would greatly enhance indoor mobile coverage with reduced needs for in-building networks. That, in turn, could greatly improve the return on investment for operators’ outdoor networks, especially when they use higher-frequency spectrum that has sufficient capacity to support indoor users – but which has poor penetration through walls and glass compared to bands below 2 GHz.

Importantly, Docomo says the aerogel does not compromise on property insulation, and therefore sustainability objectives. Currently, the need to improve insulation in the interests of energy efficiency have led to new homes and offices being built with increasingly multi-layered, insular glass, which increases the resistance to radio waves.

The partners have got to the stage of testing the material with the aim of validating the material’s relative porousness for radio waves, but also allowing Docomo to test the interplay of various shapes and material combinations for window designs.

If the trial is successful, Docomo says it will use its market weight to encourage adoption by the construction industry in Japan and beyond, arguing that this will future-proof buildings for next generation connectivity requirements, including the potential adoption of very high-frequency spectrum in the 6G era. Docomo, which is already running mobile  networks in millimeter wave spectrum around 26 GHz, noted that it plans to conduct tests of sub-terahertz frequencies, around 100 GHz, in future.

Another example of materials and radio engineering worlds colliding is RIS, which achieved a strong position in the 6G R&D landscape when ETSI set up an Industry Specification Group for the technology in 2021. There are some early commercial implementations, though 3GPP is yet to include it in its 5G-Advanced standards roadmap – a move that may wait for Release 20, the first ‘6G’ release in 3GPP parlance.

RIS entails a fully programmable and software-defined material in which

objects are coated with man-made intelligent surfaces of configurable electromagnetic materials. These materials contain integrated electronic circuits and software that enable the control of the wireless medium. The response of the surface can be reconfigured in the electromagnetic domain to reflect radio signals impinging on the surface in a specific direction. Thousands of small antennas or meta-material elements can be used to dynamically shape and control radio signals.The resulting surface will be made of low-cost low-power components and can be applied to relatively small objects such as repeaters, or whole buildings.

RIS technology is being studied for initial inclusion in repeaters, and could address some of the challenges of directing radio waves in very high frequency spectrum. It would enable repeaters and other devices to transmit and amplify selectively and dynamically according to time, direction or frequency of the signals, and could underpin entirely new surfaces that might be used to make 6G more energy-efficient and responsive. It would underpin smart radio surfaces in which thousands of small antennas or metamaterial elements combine to shape and control radio signals dynamically, in a fluid way that is driven by goals or intents.

The technology aims to turn the whole wireless environment into a service. Several companies have recently announced contributions to the effort. Korea’s LG U+ conducted its first RIS demo with Nokia a year ago, followed by Japan’s Kyocera showing off conceptual RIS panels and a ‘Transmissive Metasurface’ targeted at 5G and 6G in high-frequency spectrum.

ETSI is looking at RIS in two main ways. One is focused on relatively short term ways to boost 5G performance and coverage, with innovations such as smart repeaters; the other is assessing entirely new wireless services using the new surfaces, such as wireless sensing.

According to ETSI, RIS will enable many new use cases, including enhanced KPIs for coverage and capacity, and new applications such as localization and sensing. For instance, RIS can reconfigure the radio environment to sense human posture and detect someone falling, which could be used in elderly care applications. Additionally, said ETSI, the characteristics of RIS may result in low energy consumption. RIS can be configured to operate in any spectrum from sub-6 GHz to ‘terahertz’.

All these new materials have the potential to boost the capacity and usability of networks cost-efficiently, but that will present a new challenge – how to handle all the signals and data that will result when every object is smothered in sensors. Docomo has another project that examines certain aspects of this issue and last week it introduced a conceptual Human Augmentation Platform, which enables remote sharing of sensations and even feelings, using special wearables co-developed by Keio University and the Nagoya Institute of Technology.

Docomo is badging this emerging technology ‘Feel Tech’, and the devices use haptic sensors to detect the wearer’s movements and vibrations, converting them into an electronic signal that is recorded and processed by the Human Augmentation Platform. The platform, in turn, sends the signals to the receiving device which uses a transducer to convert the signal back into physical sensations.

“The system will make it possible to share sensations that conventionally have been difficult, if not impossible, to convey through images, sound, text or words alone,” said Docomo in a statement. “Accordingly, the system is expected to find practical applications in fields that rely on human senses, such as medicine and art. Also, shoppers on e-commerce sites could use it to experience the subtle feel of clothing fabrics, among other rich experiences not possible using other advanced technologies such as 3D or augmented reality.”

Docomo was clear that a new level of ubiquity and low latency would be essential to turn these experiences into something usable by the general population. It said: “To achieve crucial synchronization of the haptic and video data being shared, the platform is expected eventually to make full use of the ultra-low latency that will be offered in forthcoming 6G mobile networks.”

The operator added: “In view of the wide range of devices that could be interconnected via the Human Augmentation Platform, Docomo is now collaborating with diverse partners who offer value-added technologies suited to specific devices, which is expected to support the steady expansion of sharing existing and all-new types of sensory information.”

There are obvious links to the growing ecosystem of telecoms, cloud, materials and applications stakeholders that are focused on next-generation virtual experiences, often labelled ‘metaverse’, ‘tactile Internet’ and so on. Meta itself has shown off two prototype systems, Bellowband and Tasbi, that are designed to simulate and measure physical interaction with virtual objects. The aim is, eventually, to make haptic feedback  indistinguishable from real world interaction.

Last June, Vodafone demonstrated 5G-enabled haptic suits at the Mighty Hoopla music festival in London, enabling fans with impaired hearing to feel the music through vibrations.