In this paper, the privacy of wireless transmissions is improved through the use of an efficient technique termed dynamic directional modulation (DDM), and is subsequently assessed in terms of the measure of information leakage. Recently, a variation of DDM termed low-power dynamic directional modulation (LPDDM) has attracted significant attention as a prominent secure transmission method due to its ability to further improve the privacy of wireless communications. Roughly speaking, this modulation operates by randomly selecting the transmitting antenna from an antenna array whose radiation pattern is well known. Thereafter, the modulator adjusts the constellation phase so as to ensure that only the legitimate receiver recovers the information. To begin with, we highlight some privacy boundaries inherent to the underlying system. In addition, we propose features that the antenna array must meet in order to increase the privacy of a wireless communication system. Last, we adopt a uniform circular monopole antenna array with equiprobable transmitting antennas in order to assess the impact of DDM on the information leakage. It is shown that the bit error rate, while being a useful metric in the evaluation of wireless communication systems, does not provide the full information about the vulnerability of the underlying system.

翻译：本文采用一种名为动态定向调制（DDM）的高效技术来提升无线传输的隐私性，并随后从信息泄露的角度对其进行评估。最近，一种称为低功率动态定向调制（LPDDM）的DDM变体作为一种突出的安全传输方法引起了广泛关注，因为它能够进一步提高无线通信的隐私性。大致而言，该调制通过从辐射方向图已知的天线阵列中随机选择发射天线来工作。此后，调制器调整星座相位，以确保只有合法接收者能够恢复信息。首先，我们指出了该系统固有的某些隐私边界。此外，我们提出了天线阵列必须满足的特征，以增强无线通信系统的隐私性。最后，我们采用均匀圆形单极天线阵列，并假设各发射天线等概率使用，以评估DDM对信息泄露的影响。结果表明，误码率虽然是评估无线通信系统的有用指标，但未能全面反映该系统的脆弱性。