Novel DFE for Underwater Acoustic Channels

In underwater acoustic communication systems, the channel equalization community has recently given much attention to decision feedback equalization (DFE). It is because that the DFE offers intersymbol interference (ISI) cancellation with reduced noise enhancement. However, its key algorithm such as constant modulus algorithm (CMA) has moderate convergence rate and steady-state mean square error (MSE), which is not sufficient for the receive system of communication. So a new cost function is defined and then a novel DFE based on such cost function is proposed. The efficiency of the proposed DFE is proved by computer simulations.

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Cost Function based Soft Feedback Iterative Channel Estimation in OFDM Underwater Acoustic Communication

Infocommunications journal ◽

10.36244/icj.2019.1.4 ◽

2019 ◽

pp. 29-37

Author(s):

Gang Qiao ◽

Zeeshan Babar ◽

Lu Ma ◽

Xue Li

Keyword(s):

Channel Estimation ◽

Cost Function ◽

Orthogonal Frequency Division Multiplexing ◽

Matching Pursuit ◽

Decision Feedback ◽

Underwater Acoustic Communication ◽

Soft Decision ◽

Iterative Receiver ◽

Iterative Receivers ◽

Underwater Acoustic

Underwater Acoustic (UWA) communication is mainly characterized by bandwidth limited complex UWA channels. Orthogonal Frequency Division Multiplexing (OFDM) solves the bandwidth problem and an efficient channel estimation scheme estimates the channel parameters. Iterative channel estimation refines the channel estimation by reducing the number of pilots and coupling the channel estimator with channel decoder. This paper proposes an iterative receiver for OFDM UWA communication, based on a novel cost function threshold driven soft decision feedback iterative channel technique. The receiver exploits orthogonal matching pursuit (OMP) channel estimation and low density parity check (LDPC) coding techniques after comparing different channel estimation and coding schemes. The performance of the proposed receiver is verified by simulations as well as sea experiments. Furthermore, the proposed iterative receiver is compared with other non-iterative and soft decision feedback iterative receivers.

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New Concurrent Fractionally-Spaced Blind Equalization

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.108-111.363 ◽

2010 ◽

Vol 108-111 ◽

pp. 363-368 ◽

Cited By ~ 3

Author(s):

Wei Rao ◽

Ye Cai Guo ◽

Min Chen ◽

Wen Qun Tan ◽

Jian Bing Liu ◽

...

Keyword(s):

Steady State ◽

Convergence Rate ◽

Mean Square Error ◽

Blind Equalization ◽

Mean Square ◽

Constant Modulus ◽

Constant Modulus Algorithm ◽

Underwater Acoustic ◽

Underwater Acoustic Channels ◽

Simulation Results

The paper proposes a concurrent constant modulus algorithm (CMA) and decision-directed (DD) scheme for fractionally-spaced blind equalization. The proposed algorithm makes full use of the advantages of CMA and DD algorithm. A novel rule to control the adjustment of DD’s tap weights vector is proposed which avoids the hard switch between CMA and DD in practice. Simulations with underwater acoustic channels are used to compare the proposed algorithm with the famous CMA. And the simulation results show that the proposed algorithm has faster convergence rate and lower steady state mean square error.

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