Publication

Abstract : Massive multiple-input multiple-output (MIMO) systems operating in the millimeter-wave (mmWave) frequency band support extremely high data rates. One of the major shortcoming of severe path losses in these systems is addressed by the employment of large phased array antennas with highly directional beams. Owing to the precise nature of the beams, identification of the most suitable beam for link establishment between the base station (BS) and the user equipment (UE) becomes an extremely challenging and time-consuming task. The existing two-level phased array approach is based on an exhaustive search that requires a high number of beam sweeps. In this work, a novel hierarchical fast beam search approach based on a two-level phased array is proposed for improved UE discovery in mmWave massive MIMO systems. The proposed approach leverages suitable antenna spacing and radiation pattern multiplication at two-levels to yield refined beams. The hierarchical implementation via grouped antenna units results in a refinement of the beamspace at the digital level based on the best beam direction evaluated at the analog subarray level. Extensive simulation results validate the superior performance of the proposed algorithm in terms of mean position error and the total number of beam sweeps. The investigation of misdetection probability will be considered in our future work.