A location-aware covert communication protocol in inter-environmental communication applications

In recent decades, inter-environmental wireless communications (air-water) have received special attention from the military, industry, and scientific community given their important role in research, exploration, and tactical surveillance. Meanwhile, the diversity and continuous use of this communication solution has brought about a need to boost its security, accuracy, bandwidth, and transmission capacity more than ever. However, this type of communication faces a serious challenge due to the absorption and scattering characteristics of water, reflection in the air-water interface, and the limited resources of nodes located in both air and water environments. In this regard, while many various solutions have been developed to tackle these challenges, most of them either have a limited information transmission rate and range or are not safe and aware of the location. On the other hand, the optimal efficiency of some of these solutions depends on the weather conditions, facing limitations in adverse weather conditions. Therefore, in the current research, a position-aware covert communication model is presented to establish direct wireless communication between nodes located in two environments, air and water. In the introduced model, a conceptual design of an optical system is presented, the use of which enables nodes participating in the communication to discover, track, and establish covert communication in a wide range of vision, in two NLoS and LoS modes in different operating environments. In addition, this system facilitates the determination of the optimal point of water entry and exit. In the solution presented in this model, a set of mother drones located in an area with GPS coverage is utilized to determine the absolute position of other nodes participating in the communication (operational drones, speedboats, and remotely operated vehicles (ROVs). Here, the information needed to provide direct two-way optical communication between air- and water-based nodes is collected by a hybrid network consisting of a collection of drones, speedboats, and ROVs, and transmitted to the control center through it. The simulation results demonstrate that the proposed model, compared to previous methods, not only improves security but also reduces the bit error rate and energy consumption. Additionally, this model increases the transmission range and capacity despite adverse weather conditions, water dynamics, and mobility of communication nodes.