Several companies, including Japan’s NTT Docomo, will develop direct-to-device (D2D) mobile services, delivered via a space-based non-terrestrial network (NTN) using high-altitude platform stations, otherwise known as HAPS.

Docomo was selected along with Space Compass, NTT and SKY Perfect JSAT Corporation by the National Institute of Information and Communications Technology (NICT) to develop the services. The project is part of the NICT’s Beyond 5G project, which envisions a society where connectivity is assured over the air, sea and space regardless of user location.

The project consists of two phases. Phase 1 is where the four participating companies aim to solve various technical issues and demonstrate a communication service using HAPS positioned in the stratosphere over Japan, with the goal of accelerating the commercialization of HAPS D2D communication services.

Phase 2 involves research and development on high-speed, high-capacity technology and time-division duplex (TDD) communication – where the downlink and uplink use the same frequency band but in different time slots – with the goal of expanding the business scope and applicability of HAPS services in the 6G era.

Docomo, which plans to develop a HAPS-based mobile communications business, will mainly develop ground base stations and HAPS-equipped base stations for mobile communications, focusing on maximizing service-link efficiency and capacity, according to a press release.

NTT will primarily develop the control technology of the HAPS feeder link, such as site diversity and control of the transmit power, while SKY Perfect JSAT will focus on developing alternative feeder link methods, such as satellite backhaul and improvement of connection rates through the multi-connection of ground gateway stations.

They envision HAPS-based networks that could be used to support communications during disaster situations, for ship and drone connectivity and to provide communications in mountainous and remote areas such as islands.

Earlier efforts

HAPS-based connectivity was all the rage several years ago as part of various attempts to connect the unconnected. Facebook had designs to use a fleet of solar-powered aircraft to connect people in remote parts of the world, but the Aquila project was shut down in 2018. Google introduced Project Loon in 2013 and chronicled some successes over the years, but Alphabet pulled the plug in 2021.

Of course, those endeavors are not deterring others from pursuing new efforts. Earlier this year, BT Group partnered with Stratospheric Platforms on a HAPS project designed to get coverage to the hardest-to-reach areas of the U.K.

Project leaders in that initiative also talked about using HAPS as a fallback for terrestrial networks in the event of a disaster, supporting humanitarian aid and disaster relief.

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