无线通信物理层安全问题中一类鲁棒优化问题

A Special Robust Optimization Problem in the Physical Layer Security of Wireless Communication

考虑无线通信的物理层安全模型,其中一对用户在有窃听者存在的条件下通过中继转发辅助进行通信。我们将运用物理层安全技术,即设计中继的波束成形向量,在保证用户通信质量和确保窃听者不会窃听到有用信息的同时,极小化中继的总发送功率。由于窃听者位置未知,用户与中继到窃听者的信道状态信息是不完全的,相应的优化问题是一个鲁棒优化问题。本文首先对鲁棒约束进行放缩,松弛掉其中部分鲁棒参数。通过S-引理、半定规划松弛等技巧,可以求得松弛以后的鲁棒优化问题的最优解。数值实验证实,本文提出的模型和算法相比较已有工作,可以得到更低的中继发送总功率,算法的计算复杂度更低,算法更加高效。

A physical layer security model in wireless communications is considered.Two legitimate users communicate though several relays with the presence of eavesdropper.We jointly design the relay beamforming weights,to minimize the relay total transmit power while ensuring users’quality of services and preventing the information being eavesdropped.Since the channel state information(CSI)from users and relays to the eavesdropper is imperfect,the problem is a robust optimization problem.We first relax the problem and reduce the number of robust parameters.Then we design an algorithm by using S-lemma,and solve the relaxed problem optimally.Simulation results indicate that the proposed algorithm achieves lower relay transmit power compared to the state of the art.It also enjoys lower computational cost.