Beam-Bundle Codebook for Highly Directional Access in mmWave Cellular Networks

Abstract

Codebook-based schemes are extensively deployed for initial beam access in standalone millimeter-wave networks. These schemes conduct exhaustive spatial search using wide-beams in order to cover the spatial domain with reduced number of beamforming and combining vectors. This yields reduced computational complexity and measurements. However, the wide-beams associated with the initial stages in such codebook structures suffer from poor directivity and reduced gains. Consequently, initial access procedures become more challenging in blockage and aggregated path loss scenarios. Hence, this letter presents a novel scanning access scheme that eliminates the limitations associated with wide-beam codebooks, termed beam-bundle scanning. The proposed scheme significantly improves the directivity and the gains of codebook structures and increases the scattering intensity versus the traditional scanning techniques.