Multilevel LDPC-Coded High-Speed Optical Systems: Efficient Hard Decoding and Code Optimization

Gong, Chen; Wang, Xiaodong

doi:10.1109/jstqe.2009.2034025

Cited by 3 publications

(6 citation statements)

References 26 publications

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“…6. 12 These results show that for any given code rate, changing the constellation does not greatly affect the post-FEC BER prediction if the GMI is kept constant. More importantly, and unlike for the pre-FEC BER, the prediction based on the GMI appears to work across all code rates.…”

Section: Post-fec Ber Prediction Via Gmimentioning

confidence: 79%

“…This rate is achievable with a BW decoder, without iterative decoding, using the same codebook C that achieves (12) with an optimum decoder. Note that designing a codebook by drawing symbols independently and uniformly from S corresponds to independent and equally likely bits B k .…”

Section: B Achievable Ratesmentioning

confidence: 99%

“…On the other hand, the results in [40], [41] show that C 4,16 gives higher MI than PM-QPSK at all SNRs. This indicates that C 4,16 is the best choice among these 12 The MIs and GMIs were estimated using Monte Carlo integration. constellations for capacity-approaching CM transmitters with ML decoding.…”

Section: A Achievable Rates For M = 16mentioning

confidence: 99%

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Four-Dimensional Coded Modulation with Bit-Wise Decoders for Future Optical Communications

Alvarado

Agrell

2015

J. Lightwave Technol.

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Abstract-Coded modulation (CM) is the combination of forward error correction (FEC) and multilevel constellations. Coherent optical communication systems result in a four-dimensional (4D) signal space, which naturally leads to 4D-CM transceivers. A practically attractive design paradigm is to use a bit-wise decoder, where the detection process is (suboptimally) separated into two steps: soft-decision demapping followed by binary decoding. In this paper, bit-wise decoders are studied from an information-theoretic viewpoint. 4D constellations with up to 4096 constellation points are considered. Metrics to predict the post-FEC bit-error rate (BER) of bit-wise decoders are analyzed. The mutual information is shown to fail at predicting the post-FEC BER of bit-wise decoders and the so-called generalized mutual information is shown to be a much more robust metric. For the suboptimal scheme under consideration, it is also shown that constellations that transmit and receive information in each polarization and quadrature independently (e.g., PM-QPSK, PM-16QAM, and PM-64QAM) outperform the best 4D constellations designed for uncoded transmission. Theoretical gains are as high as 4 dB, which are then validated via numerical simulations of low-density parity check codes.

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Section: Post-fec Ber Prediction Via Gmimentioning

confidence: 79%

Section: B Achievable Ratesmentioning

confidence: 99%

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Four-Dimensional Coded Modulation with Bit-Wise Decoders for Future Optical Communications

Alvarado

Agrell

2015

J. Lightwave Technol.

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“…Let x k be the transmitted coded symbol at time k. We consider an effective additive white Gaussian noise channel, e.g., the output of a linear equalizer in a single-carrier dispersive optical channel, or the output of a single-tap equalizer in an optical OFDM system [10]. The received signal at time k can be written as y k ¼ x k þ Z, where Z$CN ð0,s 2 Þ is the white complex Gaussian noise sample.…”

Section: Single-level Zigzag-coded Modulation For Gray Mappingmentioning

confidence: 99%

“…4(b) [10,13]. We consider a 2-level coded modulation scheme where the mapping bits are divided into two groups X 1 ¼ ðb 0 Þ and X 2 ¼ ðb 2 b 1 Þ.…”

Section: An Example Of 8-qammentioning

confidence: 99%