Mathematical modeling and design of RIS deployment in a RIS-assisted metal cuboid for WAIC systems

Wireless avionics intra-communications (WAIC) is an emergent research topic, since it can improve fuel efficiency and enhance aircraft safety significantly. However, there are numerous baffles in an aircraft, e.g., seats and cabin bulkheads, resulting in serious blockage and even destroying wireless communications. Thus, this paper focuses on the reconfigurable intelligent surface (RIS) deployment issue of RIS-assisted WAIC systems, to solve the blockage problem caused by baffles. We first propose the mirror-symmetric imaging principle for mathematically analyzing electromagnetic (EM) wave propagation in a metal cuboid, which is a typical structure of WAIC systems. Based on the mirror-symmetric imaging principle, the mathematical channel model in a metal cuboid is deduced in detail. In addition, we develop an objective function of RIS's location and deduce the optimal RIS deployment location based on the geometric center optimization lemma. A two-dimensional gravity center search algorithm is then presented. Simulation results show that the designed RIS deployment can greatly increase the received power and efficiently solve the blockage problem in the aircraft.