Optimization of Doppler Shift Correction Based on Frequency-Scaling Search in Underwater Acoustic Communication Using Orthogonal Signal Division Multiplexing

Underwater acoustic communication, which enables wireless data exchange in environments where radio waves are severely attenuated, plays a crucial role in enhancing the efficiency of subsea infrastructure inspection and seafloor exploration. However, underwater acoustic channels are characterized by significant delay spread, Doppler spread, and Doppler shift, all of which must be accurately estimated and compensated to ensure reliable communication. Orthogonal signal division multiplexing has proven effective in maintaining robust data transmission by jointly compensating for delay and Doppler effects. Nevertheless, correcting a large Doppler shift often requires extensive computational resources, limiting the feasibility of real-time communication. To address this challenge, we propose an optimization algorithm that adaptively restricts the Doppler search range by referencing the previously measured Doppler shift and its rate of variation. This method achieves accurate Doppler shift correction while significantly reducing computational cost. Sea trial results demonstrate that the proposed approach achieves communication performance comparable to that of the existing method while reducing the number of cross-correlation operations by 80% and the overall computation time by 62%.