11,343 research outputs found
Some remarks on multiplicity codes
Multiplicity codes are algebraic error-correcting codes generalizing
classical polynomial evaluation codes, and are based on evaluating polynomials
and their derivatives. This small augmentation confers upon them better local
decoding, list-decoding and local list-decoding algorithms than their classical
counterparts. We survey what is known about these codes, present some
variations and improvements, and finally list some interesting open problems.Comment: 21 pages in Discrete Geometry and Algebraic Combinatorics, AMS
Contemporary Mathematics Series, 201
Efficient List-Decoding of Reed-Solomon Codes with the Fundamental Iterative Algorithm
International audienceIn this paper we propose a new algorithm that solves the Guruswami-Sudan interpolation step for Reed-Solomon codes efficiently. It is a generalization of the Feng-Tzeng approach, the so-called fundamental iterative algorithm. From the interpolation constraints of the Guruswami-Sudan principle it is well known that an improvement of the decoding radius can only be achieved, if the multiplicity parameter s is smaller than the list size l. The code length is n and our proposed algorithm has a complexity (without asymptotic assumptions) of O(ls4 n2).}, keywords={Feng-Tzeng approach;Guruswami-Sudan interpolation;Reed-Solomon codes;communication complexity;efficient list-decoding;fundamental iterative algorithm;Reed-Solomon codes;communication complexity;decoding;iterative methods
Fast syndrome-based Chase decoding of binary BCH codes through Wu list decoding
We present a new fast Chase decoding algorithm for binary BCH codes. The new
algorithm reduces the complexity in comparison to a recent fast Chase decoding
algorithm for Reed--Solomon (RS) codes by the authors (IEEE Trans. IT, 2022),
by requiring only a single Koetter iteration per edge of the decoding tree. In
comparison to the fast Chase algorithms presented by Kamiya (IEEE Trans. IT,
2001) and Wu (IEEE Trans. IT, 2012) for binary BCH codes, the polynomials
updated throughout the algorithm of the current paper typically have a much
lower degree.
To achieve the complexity reduction, we build on a new isomorphism between
two solution modules in the binary case, and on a degenerate case of the
soft-decision (SD) version of the Wu list decoding algorithm. Roughly speaking,
we prove that when the maximum list size is in Wu list decoding of binary
BCH codes, assigning a multiplicity of to a coordinate has the same effect
as flipping this coordinate in a Chase-decoding trial.
The solution-module isomorphism also provides a systematic way to benefit
from the binary alphabet for reducing the complexity in bounded-distance
hard-decision (HD) decoding. Along the way, we briefly develop the
Groebner-bases formulation of the Wu list decoding algorithm for binary BCH
codes, which is missing in the literature
Iterative Algebraic Soft-Decision List Decoding of Reed-Solomon Codes
In this paper, we present an iterative soft-decision decoding algorithm for
Reed-Solomon codes offering both complexity and performance advantages over
previously known decoding algorithms. Our algorithm is a list decoding
algorithm which combines two powerful soft decision decoding techniques which
were previously regarded in the literature as competitive, namely, the
Koetter-Vardy algebraic soft-decision decoding algorithm and belief-propagation
based on adaptive parity check matrices, recently proposed by Jiang and
Narayanan. Building on the Jiang-Narayanan algorithm, we present a
belief-propagation based algorithm with a significant reduction in
computational complexity. We introduce the concept of using a
belief-propagation based decoder to enhance the soft-input information prior to
decoding with an algebraic soft-decision decoder. Our algorithm can also be
viewed as an interpolation multiplicity assignment scheme for algebraic
soft-decision decoding of Reed-Solomon codes.Comment: Submitted to IEEE for publication in Jan 200
A link between Guruswami-Sudan's list-decoding and decoding of interleaved Reed-Solomon codes
International audienceThe Welch-Berlekamp approach for Reed-Solomon (RS) codes forms a bridge between classical syndrome-based decoding algorithms and interpolation-based list-decoding procedures for list size ℓ = 1. It returns the univariate error-locator polynomial and the evaluation polynomial of the RS code as a y-root. In this paper, we show the connection between the Welch-Berlekamp approach for a specific Interleaved Reed-Solomon code scheme and the Guruswami-Sudan principle. It turns out that the decoding of Interleaved RS codes can be formulated as a modified Guruswami-Sudan problem with a specific multiplicity assignment. We show that our new approach results in the same solution space as the Welch-Berlekamp scheme. Furthermore, we prove some important properties
Faster Algorithms for Multivariate Interpolation with Multiplicities and Simultaneous Polynomial Approximations
The interpolation step in the Guruswami-Sudan algorithm is a bivariate
interpolation problem with multiplicities commonly solved in the literature
using either structured linear algebra or basis reduction of polynomial
lattices. This problem has been extended to three or more variables; for this
generalization, all fast algorithms proposed so far rely on the lattice
approach. In this paper, we reduce this multivariate interpolation problem to a
problem of simultaneous polynomial approximations, which we solve using fast
structured linear algebra. This improves the best known complexity bounds for
the interpolation step of the list-decoding of Reed-Solomon codes,
Parvaresh-Vardy codes, and folded Reed-Solomon codes. In particular, for
Reed-Solomon list-decoding with re-encoding, our approach has complexity
, where are the
list size, the multiplicity, the number of sample points and the dimension of
the code, and is the exponent of linear algebra; this accelerates the
previously fastest known algorithm by a factor of .Comment: Version 2: Generalized our results about Problem 1 to distinct
multiplicities. Added Section 4 which details several applications of our
results to the decoding of Reed-Solomon codes (list-decoding with re-encoding
technique, Wu algorithm, and soft-decoding). Reorganized the sections, added
references and corrected typo
Ideal-Theoretic Explanation of Capacity-Achieving Decoding
In this work, we present an abstract framework for some algebraic error-correcting codes with the aim of capturing codes that are list-decodable to capacity, along with their decoding algorithm. In the polynomial ideal framework, a code is specified by some ideals in a polynomial ring, messages are polynomials and their encoding is the residue modulo the ideals. We present an alternate way of viewing this class of codes in terms of linear operators, and show that this alternate view makes their algorithmic list-decodability amenable to analysis.
Our framework leads to a new class of codes that we call affine Folded Reed-Solomon codes (which are themselves a special case of the broader class we explore). These codes are common generalizations of the well-studied Folded Reed-Solomon codes and Univariate Multiplicity codes, while also capturing the less-studied Additive Folded Reed-Solomon codes as well as a large family of codes that were not previously known/studied.
More significantly our framework also captures the algorithmic list-decodability of the constituent codes. Specifically, we present a unified view of the decoding algorithm for ideal-theoretic codes and show that the decodability reduces to the analysis of the distance of some related codes. We show that good bounds on this distance lead to capacity-achieving performance of the underlying code, providing a unifying explanation of known capacity-achieving results. In the specific case of affine Folded Reed-Solomon codes, our framework shows that they are list-decodable up to capacity (for appropriate setting of the parameters), thereby unifying the previous results for Folded Reed-Solomon, Multiplicity and Additive Folded Reed-Solomon codes
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