The trial took place in the United States in August, when the Zephyr S aircraft undertook 18 stratospheric test flights to simulate future direct-to-device connectivity.
Tests were conducted across 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.
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. The trial involved a radio propagation experiment from the stratosphere at an altitude of approximately 20 kilometers to a receiving antenna on the ground.
Takehiro Nakamura, general manager of Docomo’s 6G-IOWN department, said: “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.”
Based on the results of the trial, Airbus and NTT have said they will work together to provide enhanced communication services via devices including smartphones in mountainous areas, remote islands, and maritime areas where radio waves are difficult to reach. In addition to coverage of the air and sea, stratospheric HAPS networking is expected to be used for disaster preparedness and industrial use cases to increase communication capacity in densely populated areas and remotely controlling heavy equipment at construction sites.
Stephane Ginoux, head of North Asia region for Airbus, said: “Billions of people across the world suffer from poor or no connectivity. These tests show us the viability of the stratosphere to bridge this divide and provide direct to device connectivity via Zephyr without the need for base stations or extra infrastructure.”
