Soft Direct-Adaptive Turbo Equalization for MIMO Underwater Acoustic Communications


A Soft Direct-Adaptive Turbo Equalization (Soft DA-TEQ) is proposed for robust MIMO UWA communications. The proposed Soft DA-TEQ is derived under on the general frame of Expectation Maximization (E.M.) algorithm, which utilize the a priori soft decisions from the decoder to direct the equalizer's coefficients adaptation. The a priori soft decisions directed adaptation effectively lower the error propagation, which often cause catastrophic performance degradation in Hard DA-TEQ. Besides, in each iteration of the E.M. based soft adaption, the reliability of the symbol estimation is updated and used in the next iteration of soft adaption, which further enhances the convergence of the DA-TEQ. Experimental results show that the proposed Soft DA-TEQ is capable of robust detection in fast time varying MIMO UWA channels, even with low pilot overhead.

Meeting Name

OCEANS '15 MTS/IEEE Washington (2015, Oct. 19-22, Washington, DC)


Electrical and Computer Engineering

Keywords and Phrases

Algorithms; Channel estimation; Equalizers; Image segmentation; Iterative methods; Maximum principle; MIMO systems; Turbo codes; Adaptive equalization; Coefficients adaptation; Error propagation; Expectation - maximizations; Performance degradation; Symbol estimation; Turbo equalizations; Underwater acoustic communications; Underwater acoustics; Bidirectional soft decision feedback equalizer (Bi-SDFE); Multiple-input-multiple-output (MIMO); Underwater acoustic (UWA) communications

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Document Type

Article - Conference proceedings

Document Version


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© 2015 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Oct 2015