Circle Track Antenna-Assisted Beamforming for Multiuser MIMO Communication Systems

This paper investigates beamforming in a multiuser multiple-input multiple-output (MIMO) communication system assisted by a new type of circle track antenna (CTA) that can move along a circular trajectory. With this CTA structure, we formulate a sum rate maximization problem by jointly optimizing the beamforming and rotation angles of the CTAs, and transform it into an equivalent weighted minimum mean square error (WMMSE) minimization problem for efficient solution. To solve this highly non-convex problem, we use alternating optimization strategy to decompose the WMMSE problem into two sub-problems corresponding to the beamforming and the antenna rotation optimization, respectively. Specifically, in rotation angle optimization, we perform variable substitution to transform the optimization variables into ones with a constant modulus constraint and solve the problem using the manifold optimization (MO) method. Simulation results demonstrate that the proposed algorithm significantly outperforms the benchmark schemes.