Downlink Beamforming with Pinching-Antenna Assisted MIMO Systems

Pinching antennas have been recently proposed as a promising flexible-antenna technology, which can be implemented by attaching low-cost pinching elements to dielectric waveguides. This work explores the potential of employing pinching antenna systems (PASSs) for downlink transmission in a multiuser MIMO setting. We formulate the problem of hybrid beamforming, where the digital precoder at the access point and the activated locations of the pinching elements are jointly designed to maximize the achievable weighted sum-rate. Invoking fractional programming, a novel low-complexity algorithm is developed to iteratively update the precoding matrix and the locations of the pinching antennas. We validate the proposed scheme through extensive numerical experiments. Our investigations demonstrate that using PASSs, the throughput can be significantly boosted compared to conventional fixed-location antenna systems. This enlightens the potential of the PASS as an enabling candidate for next-generation wireless networks.