Han Ruigang, Jia Ning, Guo Zhongyuan, Huang Jianchun, Xiao Dong, Guo Shengming
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Key Laboratory of Underwater Acoustic Environment, Chinese Academy of Sciences, Beijing 100190, China.
Sensors (Basel). 2022 May 18;22(10):3821. doi: 10.3390/s22103821.
The continuous phase modulation (CPM) technique is an excellent solution for underwater acoustic (UWA) channels with limited bandwidth and high propagation attenuation. However, the severe intersymbol interference is a big problem for the algorithm applying in shallow water. To solve this problem, an algorithm for prefiltered single-carrier frequency-domain equalization (PF-SCFDE) is presented in this paper. The regular whitening filter is replaced by a prefilter in the proposed algorithm. The output information sequence of this prefilter contains the forward information. To improve the performance, the output of the equalizer, combined with the forward information, is used to make the maximum likelihood estimation. The simulation results with minimum-shift keying and Gaussian-filtered minimum-shift keying signals over shallow water acoustic channels with low root mean square delay spread demonstrate that PF-SCFDE outperformed the traditional single-carrier frequency-domain equalization (SCFDE) by approximately 1 dB under a bit error rate (BER) of 10. A shallow sea trial has demonstrated the effectiveness of PF-SCFDE; PF-SCFDE had a reduction in BER of 18.35% as compared to the traditional SCFDE.
连续相位调制（CPM）技术是解决带宽有限且传播衰减大的水声（UWA）信道的一种出色方案。然而，严重的码间干扰对于应用于浅水区的算法来说是个大问题。为解决此问题，本文提出了一种预滤波单载波频域均衡（PF-SCFDE）算法。在所提算法中，常规的白化滤波器被一个预滤波器取代。该预滤波器的输出信息序列包含前向信息。为提高性能，均衡器的输出与前向信息相结合用于进行最大似然估计。在具有低均方根时延扩展的浅海水声信道上对最小频移键控和高斯滤波最小频移键控信号进行的仿真结果表明，在误码率（BER）为10时，PF-SCFDE比传统单载波频域均衡（SCFDE）性能优约1 dB。一次浅海试验证明了PF-SCFDE的有效性；与传统SCFDE相比，PF-SCFDE的误码率降低了18.35%。
