Dynamic Array-of-Subarrays Architecture for Wideband Multi-Antenna Systems

Abstract

Recently, wideband beamforming realized by extremely large-scale antenna array (ELAA) systems have garnered significant interest as a means to dramatically improve throughput of next generation (xG) networks. However, traditional phase shifter (PS)-based beamforming schemes might not work well in wideband ELAA systems due to the beam squint effect, where beams at different frequencies become misaligned. While the use of true time delay (TTD) can mitigate the beam squint effect by generating frequency-dependent beamforming vectors, the conventional TTD-based beamforming schemes suffer from significant array gain loss caused by the discrepancies between the desired directional beams and the generated beams. This beam misalignment issue becomes even more pronounced in the wideband ELAA systems due to the nonlinear near-field characteristics described by the spherical wave propagation. In this paper, we propose a wideband dynamic array-of-subarrays (WDAoSA) architecture that dynamically configures connections between TTDs and PS subarrays using a switch network. By optimizing the subarray connections as well as the TTD time delays and PS phase shifts, WDAoSA can effectively maximize the array gain of wideband ELAA systems. Numerical results demonstrate that WDAoSA achieves significant improvements in terms of array gain and spectral efficiency over the conventional TTD-based beamforming schemes.