Soft-In Soft-Out DFE and Bi-Directional DFE

Jeong, Soon Young; Moon, Jaekyun

doi:10.1109/tcomm.2011.063011.100501

Cited by 21 publications

(50 citation statements)

References 13 publications

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“…In [17], when the outputs of the forward and reversed DFEs were combined, it was shown that the sensitivity of the combiner output to the error in estimating the LLR correlation coefficient was reduced greatly if the variances of the two DFE outputs were assumed equal. Here we adopt the same strategy and assume that N a,B = N e,B = N or λ = 1 to reduce the sensitivity of the combiner output to the error in estimating ρ B .…”

Section: A Generation Of Uncorrelated a Priori Informationmentioning

confidence: 99%

“…See, for example, [4]- [17]. Some of these schemes utilize reduced-trellis approaches while others rely on filterbased methods such as the linear equalizer (LE) or the decision feedback equalizer (DFE).…”

Section: Introductionmentioning

confidence: 99%

“…The low complexity method does not result in a significant performance loss "bi-directional" DFE (BiDFE) algorithm takes advantage of different decision error and noise distributions at the outputs of the forward and time-reversed DFEs. Moreover, unlike the LE or the DFE, the BiDFE algorithm can be designed to avoid performance degradation even when the filter taps are constrained to be time-invariant [17]. The BiDFE can be considered as a parallel concatenated scheme with two suboptimal DFEs producing somewhat correlated yet significantly different extrinsic information.…”

Section: Introductionmentioning

confidence: 99%

“…The time-reversal operation applied to the reverse DFE can be viewed as a type of interleaving that attempts to make two input streams going into the forward and reverse DFEs appear independent. In [17], an effective log-likelihood-ratio (LLR) combining strategy for the two bi-directional DFEs has been proposed. The work of [17] also showed a new extrinsic formulation that can effectively suppress error propagation in the DFE leading to improved performance of the DFE-based turbo equalizer relative to the LE-based one.…”

Section: Introductionmentioning

confidence: 99%

“…In [17], an effective log-likelihood-ratio (LLR) combining strategy for the two bi-directional DFEs has been proposed. The work of [17] also showed a new extrinsic formulation that can effectively suppress error propagation in the DFE leading to improved performance of the DFE-based turbo equalizer relative to the LE-based one. When each DFE employs the extrinsic information formulation method of [17] and a LLR combining strategy of [17] is used, the BiDFE is shown to perform considerably better than the LE.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Self-Iterating Soft Equalizer

Jeong

Moon

2013

IEEE Trans. Commun.

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A self-iterating soft equalizer (SISE) consisting of a few relatively weak constituent equalizers is shown to provide robust performance even in severe intersymbol interference (ISI) channels that exhibit deep nulls and valleys within the signal band. Constituent equalizers are allowed to exchange soft information in the absence of interleavers based on the method that are designed to suppress significant correlation among their soft outputs. The resulting SISE works well as a stand-alone equalizer or as the equalizer component of a turbo equalization system. The performance advantages over existing methods are validated with bit-error-rate (BER) simulations and extrinsic information transfer (EXIT) chart analysis. It is shown that in turbo equalizer setting the SISE achieves performance closer to the maximum a posteriori probability equalizer than any other known schemes in very severe ISI channels.

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Section: A Generation Of Uncorrelated a Priori Informationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-Iterating Soft Equalizer

Jeong

Moon

2013

IEEE Trans. Commun.

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Spatial and Time-Reversal Diversity Aided Least-Symbol-Error-Rate Turbo Receiver for Underwater Acoustic Communications

Zhong

et al. 2018

IEEE Access

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Time-Frequency Domain Turbo Equalization for Single-Carrier Underwater Acoustic Communications

He¹,

Jing²,

Xi³

et al. 2019

IEEE Access

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Single-carrier frequency-domain equalization (SC-FDE) is a promising technique for coherent high-rate underwater acoustic (UWA) communications. In this paper, a time-frequency domain turbo equalization (TFD-TE) scheme is proposed for single-carrier modulation. The TFD-TE scheme is to couple a multi-channel frequency domain equalizer with phase rotation compensation and a low-order single-channel time-domain turbo equalizer. To mitigate the error propagation and further enhance receiver performance, a bidirectional equalizer that combined the soft outputs of a conventional equalizer and a backward equalizer is introduced into the proposed TFD-TE scheme (Bi-TFD-TF). The sparse channel is estimated by the improved proportionate normalized least mean squares (IPNLMS) algorithm block by block. Both the simulated and experimental results show the proposed TFD-TE can effectively improve system performance with acceptable complexity. The proposed TFD-TE scheme is evaluated using communication data collected from the DJK15 lake experiment. For the 1 × 4 single-input multiple-output (SIMO) communication system using quadrature phase shift keying (QPSK) and 8-phase shift keying (8PSK) modulations, the proposed scheme achieves error-free transmission after a few iterations. Our receiver achieves a maximum raw data rate of 12 kbit/s and a reliable net data rate of 4 kbit/s within 4-kHz bandwidth at a range of 10.8 km. Compared with conventional frequency domain turbo equalization (FD-TE), the proposed TFD-TE scheme can enhance 0.8-1.3 dB in terms of output signal-to-noise ratio (OSNR). The related bi-TFD-TE provides an additional 0.8-1.7-dB OSNR improvements. INDEX TERMS Underwater acoustic communications, single-carrier modulation, time-frequency domain equalization, channel estimation, turbo equalization.

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Soft-In Soft-Out DFE and Bi-Directional DFE

Cited by 21 publications

References 13 publications

Self-Iterating Soft Equalizer

Self-Iterating Soft Equalizer

Spatial and Time-Reversal Diversity Aided Least-Symbol-Error-Rate Turbo Receiver for Underwater Acoustic Communications

Time-Frequency Domain Turbo Equalization for Single-Carrier Underwater Acoustic Communications

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