Soft Self-Handover Scheme for mmWave Communications

Abstract

Directional transmission in standalone millimeter wave networks provides aggregated gains that compensates for channel impairments and path losses. However, this saliency results in initial access and handover challenges. Namely, narrow beam transmission is vulnerable to link blockage, user mobility, sparse received power profile, increased latencies and power consumption. Hence, this paper presents a novel handover scheme that utilizes primary and redundant beams transmission at the mobile station. Here, the redundant beam is used in different modes based upon link state. Foremost, once blockage is introduced to the primary beam, then an instantaneous self-handover procedure is performed by the redundant beam to a new base station. This maintains communication sessions without the requirement for repeated beam search. Meanwhile, the redundant beam is aggregated with the primary beam for enhanced spectral efficiencies in the absence of blockage effects. The scheme deploys hybrid and digital beamforming architectures at the mobile station (MS) and base station (BS), respectively, i.e., using uninform circular arrays. The proposed scheme yields enhanced spectral efficiencies, high received power profiles, and near-instantaneous recovery times, as compared to conventional recovery schemes.