Airbus and NTT DOCOMO have tested the possibility of supplying future wireless broadband access using the solar-powered Zephyr High Altitude Platform Station (HAPS). The experiment was conducted in August in the United States, when the Zephyr S aircraft flew in the stratosphere for 18 days to assess different capabilities.   The Airbus Zephyr S, which is equipped with an onboard radio transmitter, offered a highly flexible data link during its stratospheric flight to mimic future direct-to-device connection. Test data was collected at different altitudes and during various hours of the day and night, with the goal of determining how weather conditions, varied elevation angles and aircraft flight patterns influence connectivity in the stratosphere.   Various bandwidths were used in the tests to replicate direct-to-device services from the HAPS to end-users at low, nominal and high capacity. The demonstration proved the practicality and adaptability of the 2GHz spectrum for HAPS-based services,…