Millimeter-wave beam misalignment effects of small- and large-scale user mobility based on urban measurements

ABSTRACTEnabling high rate mm-wave connectivity requires precise directional antenna beam alignment, and extensive beam management to maintain it in case of user mobility. In this paper we present the results of an extensive evaluation of mm-wave beam misalignment effects of small- and large-scale user mobility based on fine-grained 3D channel measurements obtained using phased antenna arrays in Aachen, and additional small-scale device movement measurements for selected user walks and device use-cases. Our results show azimuth beam misalignment due to small-scale mobility of up to 34° on average over the walk, and high variability and dependence on the walking trajectory and device use-case. This is reflected in increased beam steering effort required to maintain best achievable data rate -- up to 26°, or 60% increase on average, compared to the reference scenario considering only large-scale mobility. Results also show that beam misalignment due to small-scale mobility, if it is not compensated, can lead to severe data rate loss, i.e. up to 85% on average over the walk, and even link outages for prolonged periods of the walk. Overall, our results suggest it is requisite for mm-wave beam management protocols to compensate the additional misalignment due to small-scale user mobility, either through rapid network-side beam tracking, or locally at the user device, to maintain high rate mobile connectivity.