Computationally Efficient Constant-Envelope Precoding Algorithm for MISO Multicasting Using PSK Modulation

Constant envelope (CE) precoding is a transmission scheme facilitating the use of low-cost radio-frequency power amplifiers in the transmitter. Herein, we consider CE precoder designs for multiple-input-single-output multicast systems using phase-shift-keying modulation. A new CE precoder is proposed that first smooths the objective function in the max-min received signal-to-noise-ratio (RSNR) design problem, which is then solved through the projected gradient framework. Simulation results revealed that the proposed CE precoders can achieve similar or superior minimum RSNR with much lower computational complexity compared with existing semidefinite-relaxation-based CE precoders.