Robust Synthesis Method for Secure Directional Modulation With Imperfect Direction Angle
Robust Synthesis Method for Secure Directional Modulation With Imperfect Direction Angle
复制标题
DOI：
10.1109/lcomm.2016.2550022
复制
发表时间：
2016-04
期刊：
影响因子：
--
通讯作者：
Jinsong Hu;F. Shu;Jun Yu Li
中科院分区：
文献类型：
--
作者：
Jinsong Hu;F. Shu;Jun Yu Li
定向调制(DM)是一种保密传输技术，它能够保持发射信号沿期望方向的原始星座，同时使星座在不期望的方向上失真。在这封信中，我们开发了新的和稳健的DM合成方法来提高传输性能。具体地说，我们首先提出了一种低复杂度的动态DM综合方法。在该方法中，我们推导出目标方向上导引向量的共轭转置的零空间的闭式表达式。基于推导出的表达式，我们构造了一个投影矩阵，以形成对这些不希望看到的方向的人为噪声。然后，我们将注意力集中在更实际的场景中，其中估计的方向角存在不确定性。这种不确定性将导致估计误差，并严重危害期望方向上的接收性能。为了减少不确定性的影响，我们进一步提出了一种基于条件最小均方误差的稳健DM综合方法。该方法的目标是使星座点沿目标方向的变形最小。仿真结果表明，与现有方法相比，本文提出的稳健DM方法能够显著提高误码率性能。
Directional modulation (DM) is a secure transmission technology that is able to retain the original constellation of transmitted signals along the desired direction, while distort the constellation in the undesired directions at the same time. In this letter, we develop novel and robust DM synthesis methods for enhancing the transmission performance. Specifically, we first propose a low-complexity dynamic DM synthesis method. In this method, we derive a closed-form expression for the null space of conjugate transpose of the steering vector in the desired direction. Based on the expression derived, we construct a projection matrix in order to form artificial noises to those undesired directions. Then, we focus our attention on more practical scenarios, where there is uncertainty in the estimated direction angle. This uncertainty will cause estimation errors and seriously jeopardize the receiving performance in the desired direction. To mitigate the uncertainty effect, we further propose a robust DM synthesis method based on conditional minimum mean square error. The proposed method aims to minimize the distortion of the constellation points along the desired direction. Simulation results show that our proposed robust DM method is capable of substantially improving the bit error rate performance compared with the state-of-the-art methods.