Channel model for simultaneous backhaul and access for mmWave 5G outdoor street canyon channel

Abstract

Millimeter waves (mmWaves) with very wide frequency bands are proposed for 5G new radio to deliver higher data-speed and capacity. Transmission using mmWaves suffers significant path loss and can be compensated by employing directional antennas. The narrow-beam directional antennas act as spatial filters that filter out multipaths falling outside their beam area. This, together with the insignificance of diffraction and diffused scattering in urban outdoors causes mmWave outdoor channel multipath to be spatially sparse with few specular reflections, posing unique requirements on channel modeling. In this paper, we have derived a low complexity mmWave directional channel model based on ray tracing for the urban microcell street canyon environment. A comprehensive characterization of outdoor links in various realistic scenarios including, line of sight (LOS)/non-LOS, beam aligned/unaligned and road canyon with/without crossroads is presented. The model captures azimuth and elevation directions of propagation in 3D plane by using a highly directional horn antenna design. Atmospheric absorption loss of mmWave is also modeled to enhance the model’s accuracy and generality. The model is validated against measurements reported in the literature. Furthermore, the channel is studied for varying propagation conditions, antenna beamwidths and polarizations, transmitter/receiver heights and positions, and street deployment parameters. Additionally, we propose a metaheuristic algorithm called particle swarm optimization to simultaneously optimize the deployment parameters that minimize path loss as the objective function. The proposed model helps in mmWave system evaluation without the necessity for any costly measurement setup or complex off-the-shelf ray tracing model.