This letter investigates the secure transmission in a multi-user massive MIMO system over Ricean fading channel in the presence of a multi-antenna eavesdropper. In order to reduce the system complexity and the channel estimation overhead, a low-complexity beamforming (BF) scheme using only the specular component is presented. Moreover, the generation of artificial noise (AN) is employed at the base station (BS) for additional security enhancement. Specifically, a tractable closed-form lower bound for the achievable ergodic secrecy rate is derived. Furthermore, the optimal power allocation factor between the transmit data power and AN signal power with fixed total power limit is obtained based on the asymptotic analysis to maximize the achievable ergodic secrecy rate. The analytical results reveal that the ergodic secrecy rate improves with the increase of Ricean ${K}$ -factor and converges to a specific constant when increasing the number of antennas at the BS. The performance of the proposed scheme is evaluated through comprehensive simulations.

中文翻译：

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基于镜面分量的波束成形和莱斯衰落信道上的人工噪声在大规模 MIMO 系统中的安全传输

这封信研究了在多天线窃听者存在的情况下，多用户大规模 MIMO 系统在莱斯衰落信道上的安全传输。为了降低系统复杂度和信道估计开销，提出了一种仅使用镜面反射分量的低复杂度波束成形（BF）方案。此外，在基站 (BS) 处采用人工噪声 (AN) 的生成以进一步增强安全性。具体来说，导出了可实现的遍历保密率的易处理的封闭形式下界。此外，基于渐近分析获得发射数据功率与固定总功率限制的AN信号功率之间的最佳功率分配因子，以最大化可实现的遍历保密率。 ${K}$ -factor 并在增加 BS 处的天线数量时收敛到一个特定的常数。通过综合模拟评估所提出方案的性能。