Comparing Power Scattered by RIS with Natural Scatter around Urban Corners

Reflective Intelligent Surfaces (RIS) are considered promising in improving coverage in Non-Line of sight (NLOS) wireless links, especially at mm wave bands. Coverage provided by RIS is here compared to coverage from such ambient propagation mechanisms as scattering from street poles, rough building walls and corner diffraction. It is found that such background scatter provides signal levels around an urban street corner comparable to that of an ideal 0.3m x 0.3 m RIS at 28 GHz. Larger area RIS is thus required to deliver substantial gain in such a scenario.