Research on Demodulation Algorithms for Cross-medium Communication Combining Acoustic and Electromagnetic Waves

Cross-medium direct communication holds significant research value because of its potential to address the shortcomings of traditional cross-medium communication with relay, such as poor concealment and low efficiency. A recently proposed cross-medium method that combines acoustic and electromagnetic waves appears promising. However, the complicated and difficult-to-estimate environment of underwater acoustic channels places a heavy burden on the selection of modulation schemes. In order to explore suitable modulation strategies for this cross-medium scheme, this paper establishes a theoretical model of cross-medium communication, analyses the experimental channel, and builds a simulation platform. In the simulation experiments, we investigated the impacts of orthogonal frequency division multiplexing (OFDM), phase-shift keying (PSK), and quadrature amplitude modulation (QAM) modulation. The results demonstrate that the combined acoustic-electromagnetic cross-medium channel is time-invariant. OFDM offers a better balance of transmission quality and efficiency compared with single-carrier modulation.