Frequency domain direct adaptive turbo equalization based on block normalized minimum-SER for underwater acoustic communications

The equalization based on the mean square error (MSE) criterion has been widely used in underwater acoustic (UWA) communication and has shown promising results. MSE is, however, a suboptimal crite-rion for the evaluation of bit error rate (BER), the key sign of communication quality. In this paper, another criterion, the minimum symbol error rate (MSER) criterion, is used to design the equalizer of UWA communication. A novel frequency domain block normalized minimum symbol error rate (FBNMSER) algorithm is proposed. Different from the existing MSER-based method performed in the time domain, the proposed FBNMSER algorithm is worked in the frequency domain. Meanwhile, the proposed algorithm is applied to a frequency domain adaptive turbo equalizer, named FBNMSER-DATEQ. The per-formance of the FBNMSER-DATEQ is validated using simulation and data from real-world underwater experiments. The effectiveness and superiority of the proposed method can be demonstrated using both simulation and experimental results.(c) 2023 Elsevier Ltd. All rights reserved.