This study investigates information and secrecy capacity over broadcast channels through the use of directional modulation. The authors develop and demonstrate the utility of an antenna array control technique that provides communication devices with enhanced information and secrecy capacity by time-varying the array steering vectors using a novel beam control method. They show that an increase in the achievable capacity in a broadcast communication system beyond the currently-accepted Sato bound is possible by using the time domain of array steering vectors as an additional degree of freedom. Furthermore, they increase the overall secrecy capacity of the system by spatially restricting the successful reception of signals. In practical terms, this results in higher-rate, confidential messages for multiple devices for a given power constraint. They present simulation results of the array steering technique showing that direction-dependent modulation can provide broadcast channel capacity and secrecy capacity exceeding theoretical bounds for conventional, static coding techniques. They further describe an experiment and share measured results that corroborate the simulated results at the physical layer and provide insight into the proposed method.

中文翻译：

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定向调制方法以增加广播信道上机密消息的容量

这项研究通过使用定向调制来研究广播信道上的信息和保密容量。作者开发并证明了天线阵列控制技术的实用性，该技术通过使用新颖的波束控制方法使阵列控制向量随时间变化，从而为通信设备提供增强的信息和保密能力。他们表明，通过将阵列控制向量的时域用作附加自由度，可以将广播通信系统中可实现的容量增加到当前接受的Sato范围之外。此外，它们通过在空间上限制信号的成功接收来增加系统的整体保密能力。实际上，对于给定的功率约束，这会导致多个设备获得更高速率的机密消息。他们提供了阵列控制技术的仿真结果，结果表明方向相关的调制可以提供超出常规静态编码技术理论范围的广播信道容量和保密容量。他们进一步描述了一个实验并分享了测量结果，这些结果证实了物理层的模拟结果，并为所提出的方法提供了见识。