Directional Measurements in Urban Street Canyons from Macro Rooftop Sites at 28 GHz for 90% Outdoor Coverage

TL;DR

This study characterizes path gain and directional gain at 28 GHz in urban street canyons using extensive rooftop measurements, revealing significant variation and modeling coverage losses for outdoor macro cellular deployments.

Contribution

It provides empirical models for path gain, diffraction, and antenna gain degradation based on a large dataset, aiding design of outdoor 5G coverage in urban environments.

Findings

Median street path gain varies over 30 dB at similar distances.

Coverage loss directly illuminated by roof edge antenna averages 11 dB at 200 m.

Effective azimuthal gain degradation is limited to 2 dB for 90% of data.

Abstract

Path gain and effective directional gain in azimuth in urban canyons from actual rooftop base station sites are characterized based on a massive data set of 3000 links on 12 streets in two cities, with over 21 million individual continuous wave power measurements at 28 GHz using vertically polarized antennas. Large street-to-street path gain variation is found, with median street path gain varying over 30 dB at similar distances. Coverage in the street directly illuminated by a roof edge antenna is found to suffer an average excess loss of 11 dB relative to free space at 200 m, with empirical slope-intercept fit model representing the data with 7.1 dB standard deviation. Offsetting the base antenna 5 m away from roof edge, as is common in macro cellular deployments, introduces an additional average loss of 15 dB at 100 m, but this additional loss reduces with distance. Around the corner loss is well modeled by a diffraction formula with an empirically obtained diffraction coefficient. Effective azimuthal gain degradation due to scatter is limited to 2 dB for 90% of data, supporting effective use of high gain antennas in urban street canyons.