2021 Volume 10 Issue 12 Pages 948-953
HAPS (High-Altitude Platform Station) is expected to extend the communication coverage in the era of beyond 5G. HAPS moves around a circle at 20km altitude and tries to make beams fixed on the earth by beamforming. However, if HAPS uses polarization like satellite communication, there is a possibility that received SNR (Signal to Noise power Ratio) degrades because the fluctuation of HAPS aircraft could generate polarization mismatch between HAPS and earth stations. This paper reports experimental results using on-air polarization signal from a satellite with artificial polarization offset to evaluate feasibility of polarization utilization in HAPS. The results show SNR loss due to the polarization offset can be confined within 0.5dB and good tracking performance thanks to the polarization diversity by MMSE (Minimum Mean Square Error) receiver.
