High Altitude Platform Station (HAPS) to Satellite Channel Models for 6G Networks

It is widely acknowledged that flexible and agile solutions for wireless connectivity will play a key role in the next generation communication systems, and High Altitude Platform Station (HAPS) will be one of these solutions as an indispensable part of wireless networks. In this article, we investigate the modeling of the communication channel between HAPS and satellites. Considering the factors affecting the quality of the communication channel and the location of the HAPS, we predicted that analysis of electromagnetic wave propagation through ionosphere layers may become critical. This paper mostly focuses on the effects of plasma density variation on the ionospheric communication channel. We firstly analyze the effect of magnetic field on the refractive index confirm that it can indeed be ignored, as frequently assumed in the literature. Then the effects of Total Electron Content (TEC) amount on path loss are analyzed by the Appleton-Hartree modeling of refractive index. Using the maximum electron densities of the layers we adapt the Chapman model for HAPS-to-satellite channels. Extensive numerical results are provided.