Simplified Channel Model for Medium- and Long-Range Underwater Electromagnetic Communication in Nonhomogeneous Seawater

With the continuous advancement of ocean observation technologies, ocean information sensing networks have evolved beyond traditional underwater sensors and are gradually expanding into multi-dimensional observation systems that incorporate aerial nodes. To enable effective collaboration among multiple nodes, efficient information exchange is essential. Underwater electromagnetic communication (UEMC) plays a vital role in ocean observation networks as a key means of data transmission. However, due to the non-uniformity of EM parameters in the real marine environment and the need for wide-area observational network coverage, accurate channel modeling for medium- and long-range UEMC is required in non-homogeneous seawater. Traditional channel modeling techniques based on propagation models frequently require solving the Sommerfeld integral, which results in increased modeling complexity and high computational cost. Moreover, this reliance restricts the physical interpretability and practical application of the model. To address these limitations, a simplified channel model for medium- and long-range UEMC in non-homogeneous seawater is proposed. The model is extended from the UEMC channel in homogeneous seawater, explicitly accounting for the impact of spatial variations in seawater EM parameters on absorption loss and transmission attenuation. Numerical simulations demonstrate good agreement between the proposed model and the reference model obtained based on propagation model. In addition, compared to the reference model, the simplified model achieves significantly higher computational efficiency, and its performance remains stable regardless of changes in horizontal distance, operating frequency, or the number of seawater layers. Moreover, the simplified model demonstrates an explicit relationship between environmental and communication parameters and channel characteristics, which provides a theoretical foundation for the deployment and parameter optimization of communication systems.