Fig. 1
From: Low complexity channel estimation algorithm using paired spatial signatures for UAV 3D MIMO systems
UPA signal model. This is UPA signal model. Depicts a UPA signal model. The antenna is evenly distributed on the xoy plane, and the antenna spacing of the x-axis and the y-axis is d. \(\phi_{k}\), \(\theta_{k}\) denote the signal elevation angle and azimuth of the kth user respectively. \(\alpha_{k}\), \(\beta_{k}\) denote the angle between the incident signal and the x- and y- directions of the kth user respectively