In this letter, we study the interacting effects of the exclusion zone and eavesdropper colluding strategy on the secrecy performance of multiple-antenna transmission system. In particular, a base station (BS) applies random beamforming and user scheduling to enhance the legitimate user channel while multiple eavesdroppers try, either individually or jointly, to overhear the transmitted signal. We derive the closed-form expressions of secrecy outage probability (SOP) of the system with and without exclusion zone under different colluding strategies. Through selected numerical examples, we develop the design guideline on the size of the exclusion zone for a target security level subject to eavesdroppers’ density and colluding strategy.

中文翻译：

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具有用户调度的随机波束成形传输的保密中断分析：共谋与排除

在这封信中，我们研究了禁区和窃听者共谋策略对多天线传输系统保密性能的交互影响。特别是，基站 (BS) 应用随机波束成形和用户调度来增强合法用户信道，同时多个窃听者单独或联合尝试窃听传输的信号。我们推导出了不同共谋策略下有禁区和无禁区系统的保密中断概率（SOP）的闭式表达式。通过选定的数值示​​例，我们针对受窃听者密度和共谋策略影响的目标安全级别制定了有关禁区大小的设计指南。