In this paper, we derive the link budget relations for<br>communications assisted by reconfigurable smart surfaces (RSS).<br>Specifically, under specular and scattering paradigms, we provide<br>link budget expressions for an RSS-assisted communication on<br>the ground, where the RSS is either mounted on a building, or on<br>an aerial platform, such as an unmanned aerial vehicle (UAV),<br>a high altitude platform station (HAPS), or a low-earth orbit<br>satellite (LEO). The obtained numerical results provide design<br>guidelines for RSS-assisted communication systems, including the<br>recommended aerial platform to use, the size of RSS for each<br>type of the platforms, and the operating frequencies.
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