974 research outputs found
Improved Decoding of Staircase Codes: The Soft-aided Bit-marking (SABM) Algorithm
Staircase codes (SCCs) are typically decoded using iterative bounded-distance
decoding (BDD) and hard decisions. In this paper, a novel decoding algorithm is
proposed, which partially uses soft information from the channel. The proposed
algorithm is based on marking certain number of highly reliable and highly
unreliable bits. These marked bits are used to improve the
miscorrection-detection capability of the SCC decoder and the error-correcting
capability of BDD. For SCCs with -error-correcting
Bose-Chaudhuri-Hocquenghem component codes, our algorithm improves upon
standard SCC decoding by up to ~dB at a bit-error rate (BER) of
. The proposed algorithm is shown to achieve almost half of the gain
achievable by an idealized decoder with this structure. A complexity analysis
based on the number of additional calls to the component BDD decoder shows that
the relative complexity increase is only around at a BER of .
This additional complexity is shown to decrease as the channel quality
improves. Our algorithm is also extended (with minor modifications) to product
codes. The simulation results show that in this case, the algorithm offers
gains of up to ~dB at a BER of .Comment: 10 pages, 12 figure
Binary Message Passing Decoding of Product-like Codes
We propose a novel binary message passing decoding algorithm for product-like
codes based on bounded distance decoding (BDD) of the component codes. The
algorithm, dubbed iterative BDD with scaled reliability (iBDD-SR), exploits the
channel reliabilities and is therefore soft in nature. However, the messages
exchanged by the component decoders are binary (hard) messages, which
significantly reduces the decoder data flow. The exchanged binary messages are
obtained by combining the channel reliability with the BDD decoder output
reliabilities, properly conveyed by a scaling factor applied to the BDD
decisions. We perform a density evolution analysis for generalized low-density
parity-check (GLDPC) code ensembles and spatially coupled GLDPC code ensembles,
from which the scaling factors of the iBDD-SR for product and staircase codes,
respectively, can be obtained. For the white additive Gaussian noise channel,
we show performance gains up to dB and dB for product and
staircase codes compared to conventional iterative BDD (iBDD) with the same
decoder data flow. Furthermore, we show that iBDD-SR approaches the performance
of ideal iBDD that prevents miscorrections.Comment: Accepted for publication in the IEEE Transactions on Communication
Binary Message Passing Decoding of Product Codes Based on Generalized Minimum Distance Decoding
We propose a binary message passing decoding algorithm for product codes
based on generalized minimum distance decoding (GMDD) of the component codes,
where the last stage of the GMDD makes a decision based on the Hamming distance
metric. The proposed algorithm closes half of the gap between conventional
iterative bounded distance decoding (iBDD) and turbo product decoding based on
the Chase--Pyndiah algorithm, at the expense of some increase in complexity.
Furthermore, the proposed algorithm entails only a limited increase in data
flow compared to iBDD.Comment: Invited paper to the 53rd Annual Conference on Information Sciences
and Systems (CISS), Baltimore, MD, March 2019. arXiv admin note: text overlap
with arXiv:1806.1090
A Soft-Aided Staircase Decoder Using Three-Level Channel Reliabilities
The soft-aided bit-marking (SABM) algorithm is based on the idea of marking
bits as highly reliable bits (HRBs), highly unreliable bits (HUBs), and
uncertain bits to improve the performance of hard-decision (HD) decoders. The
HRBs and HUBs are used to assist the HD decoders to prevent miscorrections and
to decode those originally uncorrectable cases via bit flipping (BF),
respectively. In this paper, an improved SABM algorithm (called iSABM) is
proposed for staircase codes (SCCs). Similar to the SABM, iSABM marks bits with
the help of channel reliabilities, i.e., using the absolute values of the
log-likelihood ratios. The improvements offered by iSABM include: (i) HUBs
being classified using a reliability threshold, (ii) BF randomly selecting
HUBs, and (iii) soft-aided decoding over multiple SCC blocks. The decoding
complexity of iSABM is comparable of that of SABM. This is due to the fact that
on the one hand no sorting is required (lower complexity) because of the use of
a threshold for HUBs, while on the other hand multiple SCC blocks use soft
information (higher complexity). Additional gains of up to 0.53 dB with respect
to SABM and 0.91 dB with respect to standard SCC decoding at a bit error rate
of are reported. Furthermore, it is shown that using 1-bit
reliability marking, i.e., only having HRBs and HUBs, only causes a gain
penalty of up to 0.25 dB with a significantly reduced memory requirement
Improving HD-FEC decoding via bit marking
We review the recently introduced soft-aided bit-marking (SABM) algorithm and
its suitability for product codes. Some aspects of the implementation of the
SABM algorithm are discussed. The influence of suboptimal channel soft
information is also analyzed.Comment: OECC 201
Iterative Soft-Input Soft-Output Decoding with Ordered Reliability Bits GRAND
Guessing Random Additive Noise Decoding (GRAND) is a universal decoding
algorithm that can be used to perform maximum likelihood decoding. It attempts
to find the errors introduced by the channel by generating a sequence of
possible error vectors in order of likelihood of occurrence and applying them
to the received vector. Ordered reliability bits GRAND (ORBGRAND) integrates
soft information received from the channel to refine the error vector sequence.
In this work, ORBGRAND is modified to produce a soft output, to enable its use
as an iterative soft-input soft-output (SISO) decoder. Three techniques
specific to iterative GRAND-based decoding are then proposed to improve the
error-correction performance and decrease computational complexity and latency.
Using the OFEC code as a case study, the proposed techniques are evaluated,
yielding substantial performance gain and astounding complexity reduction of
48\% to 85\% with respect to the baseline SISO ORBGRAND.Comment: Submitted to Globecom 202
Generalized Spatially-Coupled Product-Like Codes Using Zipper Codes With Irregular Degree
Zipper codes with irregular variable degree are studied. Two new interleaver
maps -- chevron and half-chevron -- are described. Simulation results with
shortened double-error-correcting Bose--Chaudhuri--Hocquenghem constituent
codes show that zipper codes with chevron and half-chevron interleaver maps
outperform staircase codes when the rate is below 0.86 and 0.91, respectively,
at output bit error rate operating point. In the miscorrection-free
decoding scheme, both zipper codes with chevron and half-chevron interleaver
maps outperform staircase codes. However, constituent decoder miscorrections
induce additional performance gaps.Comment: 6 pages, 11 figures, paper accepted for the GLOBECOM 2023 Workshop on
Channel Coding Beyond 5
Novel High-Throughput Decoding Algorithms for Product and Staircase Codes based on Error-and-Erasure Decoding
Product codes (PCs) and staircase codes (SCCs) are conventionally decoded
based on bounded distance decoding (BDD) of the component codes and iterating
between row and column decoders. The performance of iterative BDD (iBDD) can be
improved using soft-aided (hybrid) algorithms. Among these, iBDD with combined
reliability (iBDD-CR) has been recently proposed for PCs, yielding sizeable
performance gains at the expense of a minor increase in complexity compared to
iBDD. In this paper, we first extend iBDD-CR to SCCs. We then propose two novel
decoding algorithms for PCs and SCCs which improve upon iBDD-CR. The new
algorithms use an extra decoding attempt based on error and erasure decoding of
the component codes. The proposed algorithms require only the exchange of hard
messages between component decoders, making them an attractive solution for
ultra high-throughput fiber-optic systems. Simulation results show that our
algorithms based on two decoding attempts achieve gains of up to dB for
both PCs and SCCs. This corresponds to a optical reach enhancement over
iBDD with bit-interleaved coded modulation using quadrature amplitude
modulation
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