Low-complexity beamforming designs of sum secrecy rate maximization for the Gaussian MISO multi-receiver wiretap channel

This paper studies the beamforming design for sum secrecy rate (SSR) maximization in the Gaussian multiple-input single-output multi-receiver wiretap channel (MISO-MRWC). The optimization problem of finding the optimal beamforming algorithm is non-convex and intractable to solve using low-complexity methods. Motivated by the thinking of zero-forcing (ZF) and signal-to-leakage-plus-noise ratio (SLNR), we propose three low-complexity beamforming algorithms for finding a local SSR optimum. The simulation results show that the SLNR-based beamforming algorithm outperforms the other two algorithms with ZF preprocessing.