A Fast Kalman Equalizer for Single-Carrier Underwater Acoustic Communication

One effective means to enhance the quality of underwater acoustic (UWA) communication is to design a reasonable receiver. In this study, we propose a novel fast Kalman (FK) adaptive equalizer developed to meet the requirements for noise robustness and Doppler shift resistance in single-carrier UWA communication. We integrate phase tracking performance into the FK adaptive equalizer, enabling rapid compensation for rotating taps in the face of complex time-varying channels, further enhancing equalization performance. At-sea experiments demonstrate that the FK adaptive equalizer effectively improves the bit error rate of single-carrier UWA communication. In addition, the purpose of the proposed FK algorithm is to represent the gain vector using weight vectors derived from the forward and backward prediction problems, avoiding the inverse operation of coefficient matrices, resulting in linear <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathcal {O}(L)$</tex-math></inline-formula> complexity. Simulation results demonstrate that the FK algorithm strikes an effective balance between steady-state mean squared deviation and computational efficiency. To validate the equalization performance of FK adaptive equalizer, we propose the single-carrier communication framework for simulation and at-sea experiments, detailing both the transmission frame parameters and test parameters. Compared to other equalizers, FK adaptive equalizer effectively achieves reliability and efficiency in underwater data transmission.