Low-Complexity Phase-Only Polarforming for Multiuser MISO With Single-RF-Chain PRAs

Abstract

This letter studies multiuser (MU) downlink polarforming with equal-amplitude, phase-only polarization-reconfigurable antennas (PRAs), each driven by a single radio-frequency (RF) chain. At each base station (BS) antenna, one polarization phase is shared by all transmitted streams, while digital precoding remains user-specific. Exploiting this structure, we show that each transmit phase reduces to an exact scalar unit-modulus problem and each receive phase to an exact one-dimensional problem, for both continuous and finite-resolution control. These updates are integrated into a single weighted minimum mean-square error (WMMSE) loop, avoiding the additional penalty-dual-decomposition procedure required by more general polarforming formulations. We prove monotonic convergence of the weighted sum rate (WSR) value. Extensive simulations under cross-polarization discrimination (XPD), imperfect polarized channel state information (CSI), phase quantization, and solver comparisons demonstrate the resulting rate–complexity tradeoff against fixed-polarization, as well as amplitude-and-phase designs.