Millimeter wave beam-alignment for dual-polarized outdoor MIMO systems

Fifth generation (5G) wireless systems are expected to employ smaller cells within a heterogeneous network. Multiple antenna communication at millimeter wavelengths is a promising technology for both backhaul and access within these networks. We discuss a dual-polarized channel model for an outdoor, millimeter wave system and propose a beam-alignment algorithm that exploits the orthogonal polarizations. The proposed beam-alignment algorithm reduces the beam search time by sounding the orthogonal polarizations in parallel. Moreover, noise and interference immunity is improved with a joint search method. The proposed beam-alignment algorithm enables closed-loop multiple-input multiple-output (MIMO) communication for either backhaul or access scenarios.