This letter investigates the secure delivery performance of the rate-splitting multiple access scheme in land mobile satellite (LMS) systems, considering that the private messages intended by a terminal can be eavesdropped by any others from the broadcast signals. Specifically, the considered system has an N-antenna satellite and numerous single-antenna land users. Maximum ratio transmission (MRT) and matched-filtering (MF) precoding techniques are adopted at the satellite separately for the common messages (CMs) and for the private messages (PMs), which are both implemented based on the estimated LMS channels suffering from the Shadowed-Rician fading. Then, closed-form expressions are derived for the ergodic rates for decoding the CM, and for decoding the PM at the intended user respectively, and more importantly, we also derive the ergodic secrecy rate against eavesdropping. Finally, numerical results are provided to validate the correctness of the proposed analysis models, as well as to show some interesting comparisons.

翻译：本文针对陆地移动卫星（LMS）系统中速率分裂多址接入方案的安全传输性能展开研究，考虑终端私有信息可能被其他终端通过广播信号窃听。具体而言，所考虑系统包含一个配备N根天线的卫星与多个单天线地面用户。卫星分别采用最大比传输与匹配滤波预编码技术处理公共消息与私有消息，两项技术均基于受阴影莱斯衰落影响的LMS信道估计实现。进一步，推导出公共消息解码遍历速率与目标用户解码私有消息遍历速率的闭式表达式，更重要的是，本文还推导了针对窃听行为的遍历安全速率。最后，通过数值结果验证了所提分析模型的正确性，并展示了若干有价值的对比结论。