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

Zheng, Tonghui; Jing, Lianyou; Long, Chao; He, Chengbing; Yin, Hongxi

doi:10.1016/j.apacoust.2023.109266

Cited by 5 publications

(1 citation statement)

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“…Turbo equalization has been considered as an efficient technology to make significant improvements in bit error rate (BER) manifestation under complicated UWA environments [11,12]. Turbo equalization is derived from turbo decoders by employing a maximum a posteriori (MAP) equalizer as a replacement of one stand-alone MAP decoder in typical decoder processing [13,14]. In order to realize computational complexity in large time-delay channels, a soft-input soft-output (SISO) equalizer is introduced into the iteration structure based on the minimum mean squared error (MMSE) criterion [15][16][17], least symbol error rate (LSER) criterion [18,19] and so on.…”

Section: Introductionmentioning

confidence: 99%

Virtual Space-Time DiversityTurbo Equalization Using Cluster Sparse Proportional Recursive Least Squares Algorithm for Underwater Acoustic Communications

Han,

Tao,

Zhang

et al. 2023

Applied Sciences

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The oceanic positioning, navigation and timing (PNT) network requires high-quality underwater acoustic message transmission. Turbo equalization technology has exhibited superior performance for underwater acoustic (UWA) communications compared with conventional channel equalizers. To overcome the performance reduction caused by severe doubly selective UWA channels, the virtual space-time diversity soft direct-adaptation turbo equalization is proposed for UWA communications. The proposed scheme improves the ability of the typical turbo equalizer to deal with both Doppler and multipath effects for time varying channels. We utilize a fractionally spaced soft interference cancellation equalizer (FS-SE) instead of a hard decision to constitute the soft-input soft-output (SISO) equalizer. Combined with another virtual time-reversal mirror equalizer component, we can obtain virtual space and time diversity with only a single receiving transducer and mitigate the error propagation phenomenon of the feedback filter. To satisfy the sparse UWA channel, the ℓp,q-PRLS algorithm is applied to adaptive updates for FS-SE. In the proposed scheme, an adjustable interpolator and digital phase-locked loop are embedded into the equalizer to overcome the residual Doppler frequency shift and recover the timing distortion. Results of simulations and field lake trial show that the proposed scheme achieves better performance than existing ones under the same equalizer order.

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