Secure Communication Based on Time Modulation Array

This paper examines the application of probability-based time-modulated arrays in secure communication systems. Unlike conventional time-sequenced control, these arrays alter their on-off states based on probabilistic mechanisms. When transmitting BPSK signals, the randomness in the on-off states of each array element introduces a degree of randomness in the received signals across different directions. We have derived and analyzed the conditional entropy of the transmitted information from the receiver's perspective, given the received signals in various directions. By leveraging traditional phased-array sidelobe suppression techniques to control the probabilities of each array element, we can ensure that the conditional entropy of the receiver in non-target directions approaches 1. This implies that unauthorized receivers are unable to obtain any useful information, thereby enabling secure communication among cooperating parties.