3D propagation and environment modeling for NLOS wireless small-cell backhaul

This paper presents an overview of challenges and solutions for small-cell wireless backhaul. The different technologies, ranging from 3.5 to 80 GHz, are presented with a focus on radio propagation. Then, the new related design challenges are studied. A first case study shows the benefit of ray-tracing and 3D geographical map data for accurate NLOS link prediction. The use of a vertical-plane model can lead to large errors. Finally, the impact of antenna orientation is analyzed at 3.5 and 28 GHz. An optimum antenna orientation is key for an efficient design, especially at high frequencies. Different configurations for which the direct path is not the strongest are presented. In that case, a ray-tracing model is required.