Spatially consistent pathloss modeling for millimeter-wave channels in urban environments

This paper consider a fundamental issue of pathloss modeling in urban environments, namely the spatial consistency of the model as the mobile station (MS) moves along a trajectory through street canyons. We show that the traditional model of power law pathloss plus lognormally distributed variations can provide misleading results that can have serious implications for system simulations. Rather, the pathloss coefficient has to be modeled as a random variable that changes from street to street, and is also a function of the street orientation. Variations of the channel gain, taken over the ensemble of the whole cell (or multiple cells) thus consist of the compound effect of these pathloss coefficient variations together with traditional shadowing variations along the trajectory of movement. Ray tracing results demonstrate that ignoring this effect can lead to a severe overestimation of shadowing standard deviation. While the effect is irrelevant for “drop-based” simulations, it can have critical impact on system simulations that require spatial consistency for large-scale movement, such as most mm-wave systems.