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NTT Docomo and Airbus Demonstrate Zephyr HAPS Wireless Broadband Connectivity

NTT Docomo and Airbus have demonstrated the ability to use Airbus's solar-powered Zephyr High Altitude Platform Station (HAPS) to deliver future wireless broadband connectivity. The trial took place in the United States in August, when the Zephyr S aircraft undertook approx. 18-day stratospheric flights to test various capabilities. We have covered many of the topics here, see related blog posts link at the bottom.

A press release said:

Carrying an onboard radio transmitter, the Zephyr S provided an agile datalink during a stratospheric flight to simulate future direct-to-device connectivity. Test data was captured at different altitudes and at different times of day and night, focusing on assessing how connectivity is affected in the stratosphere by factors including weather conditions, different elevation angles and aircraft flight patterns.

Tests included various bandwidths to simulate direct-to-device service from the HAPS to end users using low, nominal and high throughput. The demonstration confirmed the viability and versatility of the 2GHz spectrum for HAPS-based services and also the use of a narrow (450MHz) band to provide connectivity in a range of up to 140km.

The measurement and analysis of the propagation of radio waves transmitted from Zephyr demonstrated the feasibility of stratospheric communications to devices such as smartphones. Based on the results of this experiment, Airbus and NTT DOCOMO aims to provide communication services to mountainous areas, remote islands, and maritime areas where radio waves are difficult to reach.

"DOCOMO believes that HAPS will be a promising solution for coverage expansion in 5G evolution and 6G," said Takehiro Nakamura, General Manager of DOCOMO's 6G-IOWN Promotion Department. "In this measurement experiment, we were able to demonstrate the effectiveness of HAPS, especially for direct communication to smartphones, through long-term propagation measurements using actual HAPS equipment. Based on these results, we would like to further study the practical application of HAPS in 5G evolution and 6G with Airbus."

As part of efforts to further advance 5G and prepare for 6G, "coverage expansion" to expand communication networks to any location, including air and sea, is being studied worldwide. To achieve this, non-terrestrial network (NTN) technology is expected to be used. In addition to coverage of the air and sea, stratospheric HAPS networking will be useful for disaster preparedness and many industrial use cases, for example, to increase communication capacity in densely populated areas such as event venues, and remotely controlling heavy equipment at construction sites.

The test data will be used to inform future LTE direct-to-device services that are expected to be provided via the Airbus Zephyr HAPS solution.

A recent article (Oct 2021) in NTT Docomo Technical Journal on 'Research on NTN Technology for 5G evolution & 6G' has details on some of the things NTT Docomo is trying to achieve with NTN solutions. It's available here.

I especially liked this comparison of HAPS-mounted stations.

(click on image to enlarge)

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