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The dream of offering wireless coverage from high-altitude platform stations (HAPS) is alive and well in Japan.
December 7, 2023
An initiative organised by the National Institute of Information and Communications Technology (NICT) will see DoCoMo, NTT, Sky Perfect JSAT, and Space Compass jointly develop direct-to-device (D2D) services delivered from flying base stations.
From the outside, it seems counter-intuitive to think of an industrialised, technologically-advanced country like Japan as one that really needs a HAPS solution. But considering it is an archipelago of 260 inhabited islands – islands that are vulnerable to earthquakes, tsunamis, and flooding – then it makes a lot more sense.
A joint press release from the four companies specifically cites "support for disaster communications, ship and drone connectivity, and communications in mountainous and remote areas such as islands" as potential use cases.
"Through this R&D project and beyond, the four participating companies are committed to improving the quality, efficiency and flexibility of HAPS services, extending mobile coverage to extreme levels, and ensuring seamless connectivity," DoCoMo et al said.
Space Compass – a joint venture between NTT and JSAT that specialises in non-terrestrial networking (NTN) and orbital data centres – will coordinate the effort. It has its own plan to launch a commercial HAPS service in Japan in fiscal 2025 (which starts next April), so it is ideally placed to take the lead role.
Its job will be to define the network service requirements and evaluate demonstrations conducted under the project.
DoCoMo will develop HAPS-equipped base stations for mobile communications, focusing on maximising service-link efficiency and capacity. It will also work on base stations for the ground network.
NTT has been tasked with developing control technology for the HAPS feeder link, such as site diversity and control of the transmit power.
Finally, satellite operator JSAT will focus mainly on developing alternative feeder link methods, such as satellite-based backhaul, and improving throughput by offering additional connectivity to ground gateway stations.
NICT has divided the project into two phases.
Phase 1 is the early commercialisation phase, under which the companies aim to overcome the technical complexities of HAPS-based D2D connectivity and carry out a demonstration using a HAPS positioned in the stratosphere over Japan.
Phase 2 is the R&D phase. This is all about preparing HAPS for the future through performance improvements, thereby expanding its usefulness and applicability to future 6G use cases.
There have been a few high-profile attempts to make a go of HAPS-based communication. Google Loon and Meta's Aquila programmes spring to mind – neither of which really got off the ground, so to speak. UK incumbent BT is currently looking into it as a means of improving rural coverage, and to that end has partnered with a company called Stratospheric Platforms.
But with the commercialisation of low Earth orbit (LEO) satellite broadband, it's hard to see HAPS as having much of role as an alternative or back-up coverage solution.
More details on the project in Japan will be presented at DoCoMo Open House '24, which is being held in Tokyo in mid-January. Hopefully that will shed more light on what HAPS can bring to the party.
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