Joint Impact of BS Height and Downtilt on Downlink Data Rate in mmWave Networks with 3D Large-Scale Antenna Arrays

Millimeter-wave (mmWave) communication plays a significant role in 5G networks. In this paper, we model a mmWave multicell network with three-dimensional (3D) large-scale antenna arrays, including the path loss and inter-cell interference. In general, the antenna downtilt of the base station (BS) determines the beamforming direction in both horizontal and vertical planes. The distance between the BS antenna and a typical user is modeled more accurately in 3D while considering the height of the BS than modeling all network nodes in a 2D plane. We investigate the joint impact of the BS antenna height and antenna downtilt on the performance of the mmWave downlink transmission in terms of the user data rate averaged over all possible locations of the user within the cell coverage area. We present numerical results to show that it is critical to jointly optimize the BS antenna height and downtilt in order to maximize the average downlink data rate across the cell coverage area, and provide useful guidelines into the 3D deployment of mmWave networks.