Cost-Effective XL-MIMO Communication with Cylinder Directly-Connected Antenna Array

Extremely large-scale multi-input multi-output (XL-MIMO) is a promising technology for the sixth generation (6G) wireless networks, thanks to its superior spatial resolution and beamforming gains. In order to realize XL-MIMO costeffectively, an innovative ray antenna array (RAA) architecture with directly-connected uniform linear array (ULA) was recently proposed, which achieves flexible beamforming without relying on traditional analog phase shifters or digital beamforming. However, RAA suffers from the signal blockage issue since its ray-configured ULAs are placed in the same plane. To address this issue, this paper proposes a novel antenna array architecture termed cylinder directly-connected antenna array (DCAA), which is achieved via multiple simple uniform circular array (sUCA) with carefully designed orientations in a layered three-dimensional structure. The so-called sUCA partitions the uniform circular array (UCA) into two sub-arrays where each sub-array has all antenna elements directly connected to achieve a desired beam direction corresponding to the sub-array's physical orientation, thus achieving full spatial coverage. Compared with the conventional ULA architecture with hybrid analog/digital beamforming (HBF), the proposed cylinder DCAA can achieve uniform spatial resolution, enhanced communication rate and lower hardware costs. Simulation results are provided to validate the promised gains of cylinder DCAA, demonstrating its great potential for high-frequency systems such as millimeter wave (mmWave) and Terahertz (THz) systems.