An initial access scheme for FDD spectrum bands in standalone millimeter-wave networks

Abstract

Millimeter-wave frequency bands pose significant challenges to cellular communications because of their increased path loss and lower robustness against signal obstruction, reflection or blocking phenomena. Beamforming is generally perceived as the most convenient solution to overcome this issue, usually relying on a combination of beam scanning and reciprocity-based precoding. However, channel reciprocity cannot be assumed in FDD spectrum bands, hence forcing initial access to rely solely on beam scanning with the subsequent impact on initial access time. This paper presents an initial access scheme applicable to FDD bands, where second-order channel statistics are exploited through digital beamforming. Link-level and Monte Carlo simulations are performed using the QuaDRiGa channel model, showing good results of the initial access time even in very low signal to noise ratio conditions.