A Novel Wideband ELAA Beam Search Algorithm Based on Beam Split Effect

Terahertz ultra-massive multiple input multiple output (THz UM-MIMO) communication systems are expected to be a key technology for sixth-generation (6G) wireless networks, owing to the terahertz spectrum’s multi-terahertz bandwidth, as well as the exceptional beamforming gain and extraordinary spatial resolution enabled by the extremely large-scale antenna arrays (ELAA). However, THz UM-MIMO technology introduces several inherent challenges, one of which is the increased complexity of channel state information (CSI) estimation compared to that in the fifth-generation (5G) wireless networks. To address this issue, we propose a beam split search (BSS) algorithm to efficiently search for communication beams without additional hardware components, such as time delayers (TDs). Additionally, we have developed a novel low-dimensional frequency division multiplexing (FDM) training beam codebook specifically optimized for BSS implementation. Simulation verification demonstrates that the BSS algorithm offers superior search accuracy compared to the existing algorithms and exhibits lower search complexity than the exhaustive beam search algorithm.