Aerial Reconfigurable Intelligent Surface Assisted Maritime Wireless Communications

Millimeter wave (mmWave) technology is capable of enhancing the capacity of maritime wireless systems. However, mountains and high-rise buildings impose high-frequency signal blockage, which limits its practical implementation in these environments. In order to mitigate the blockage problems of signal propagations caused by onshore mountains and mountainous near-shore islands, we first propose an aerial reconfigurable intelligent surface (ARIS) assisted maritime wireless communications system, where an ARIS is employed to provide wireless services for maritime users (MUs) that are within the blocked offshore areas. Then, a channel estimation protocol is proposed for our ARIS-assisted maritime wireless communications system, where an offline channel estimation scheme is conceived for estimating the channel between the onShore base station (S-BS) and ARIS, whilst an online channel estimation scheme is designed for obtaining estimates of the ARIS-MUs channel. Based on the channel estimates obtained, an iterative algorithm is provided for obtaining the optimized reflection elements of the ARIS for maximizing the achievable rate of the proposed system. Our simulation results validate the effectiveness of the proposed ARIS-assisted maritime wireless system.