A synthesis approach of direct antenna modulation for secure ship satellite communication

Communication security is a critical and increasingly challenging issue in wireless networks. Signals have the risk of being intercepted in traditional wireless communication because of the wireless propagation characteristics. There is also the same problem for ship satellite communication. The direct antenna modulation (DAM) is a promising secure communication technique, which scrambles signals in unwanted transmit spatial directions and can be implemented by phased array. As the DAM system model is established for the line of sight(LOS) propagation, it can also be applied to ship satellite communication. A two-dimension model is established in this paper. It is assumed that the DAM transmitter is mounted in the geostationary satellite. Usually, we expect that the legitimate receiver in the cooperative ship has a good demodulation performance while the illegitimate receiver in other places can hardly decrypt the data symbols correctly. A synthesis approach of direct phased array modulation based on NSGA-II algorithm is proposed in this paper. With the knowledge of legitimate and illegitimate receiver's directions, appropriate phase shifts can be synthesized for the secure communication scene mentioned above. In addition, a random phase shifts selection structure of direct antenna modulation transmitter based on this synthesis approach is also presented. Simulations are conducted to validate the effectiveness of the proposed approach in the end.