Suppression of Multipath Delay Exceeding CP Length Using MMSE Adaptive Array for Underwater Acoustic Communication

Underwater wireless communication primarily utilizes ultrasound or visible light. In underwater acoustic communication (UWAC), the significant limitations imposed by sound speed and carrier frequency lead to much larger delay spread and Doppler spread compared to terrestrial wireless communication. Due to the above constraints, orthogonal frequency division multiplexing (OFDM) in UWAC commonly employs extended symbol length and a longer cyclic prefix (CP). The throughput reduction caused by frequency limitations in UWAC poses a significant challenge. This paper proposes interference suppression and channel equalization by utilizing a minimum mean square error (MMSE) adaptive array with pilot symbols, while employing shorter OFDM symbol lengths.