Robust secure transmission for multiuser MISO systems with probabilistic QoS constraints

This paper considers a unicast multiuser multiple-input single-output (MISO) downlink system overheard by multiple single-antenna eavesdroppers. The objective is to jointly design the beamforming vectors and the artificial noise (AN) covariance matrix with imperfect channel state information (CSI) at the transmitter, such that the total transmit power is minimized while satisfying probabilistic quality of service (QoS) constraints at legitimate users and the eavesdroppers. Using Bernstein-type inequalities and the S-procedure, we recast the non-convex power minimization problem as two different convex semidefinite programs (SDPs) which can be solved using interior-point methods. Simulation results show that the proposed methods outperform a nonrobust method and the ones using the isotropic AN.创新点本文考虑了存在多个单天线窃听者的多用户单播MISO通信系统。提出了人工噪声辅助的安全波束成形发送方法。其目的为, 根据非理想信道状态信息对发送端的波束成形向量和人工噪声协方差矩阵进行联合优化, 在满足合法用户和窃听者的概率服务质量(Quality of Service, QoS)约束下, 最小化发送功率。由于无法获得概率QoS约束的解析表达式, 分别采用Bernstein-type不等式和S-过程将其转化为两种不同的确定性约束, 进而得到两种不同的半定规划(Semidefinite Program, SDP)问题。仿真结果表明所提方法的性能优于非鲁棒方法和全向人工噪声(Isotropic Artificial Noise)辅助波束成形方法。