Channel Measurement and Modelling in Nearshore Scenarios for Air-sea Communications

The Space-Air-Ground-Sea Integrated Network (SAGSIN) holds the potential to realize the vision of ubiquitous connectivity, of which air-sea communications play an essential role in the communication system. In this paper, the channel of three typical air-sea scenarios (Aerial Terminal Moving - Marine Terminal Anchoring, Aerial Terminal Hovering - Marine Terminal Moving and Two-terminal Moving) are measured, and their path loss and Doppler shift characteristics are analyzed and modelled. Firstly, comparative analyses of measured path loss are conducted, followed by model fitting using the close-in reference distance (CI) model to derive characteristic parameters. Subsequently, Doppler shift dynamics are quantified through Doppler power spectrum (DPS), which shows a high degree of consistency with the motion states of transmitter (Tx) and receiver (Rx). Notably, the mean Doppler shift is dominantly governed by the main path, as evidenced by its strong correlation with the variation of the main path in the DPS.