Propagation loss estimation for urban high altitude platform communications channel

This paper evaluates propagation path loss for downlink HAPS channel in urban environment based on simplified ray tracing model. Recently, there are of great interests on employing high altitude platform station (HAPS) as a new means of providing next generation cellular services. This paper aims at evaluating the impact of elevation and azimuth angles variation, building height, and the size of the street where the mobile terminals are located receiving the signal from HAPS. In order to examine the propagation loss experienced by this system in urban area, we developed the building block model and the ray tracing tool for simulation. We then apply the ray-tracing tool with respect to the angle variations. As a result, propagation loss as a function of elevation and azimuth angles is obtained. We compared the result with a physical-statistical model for comparison. The different scenarios clearly show the critical limitations of the mobile communication by using the concept of HAPS.