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arXiv 1801.03379cs.ITmath.IT
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乘积拓扑的极大可恢复码

On Maximally Recoverable Codes for Product Topologies

D. Shivakrishna, V. Arvind Rameshwar, V. Lalitha, Birenjith Sasidharan

摘要:

给定局部奇偶校验约束的拓扑结构,最大可恢复码(MRC)可以纠正所有信息理论上可纠正的擦除模式。在网格状拓扑中,在形成列代码的每一列中存在$a$局部约束,在形成行代码的每一行中存在$b$局部约束,并且在码字的$(m \times n)$网格中存在$h$全局约束。最近,Gopalan等人发起了网格拓扑下的MRC的研究,并导出了当$a=1, h=0$时擦除模式可恢复的充要条件,称为正则性条件。在本文中,我们考虑MRCs的产品拓扑($h=0$)。首先,我们基于满足乘积拓扑正则性条件的擦除模式(任意$a, b$,$h=0$)构造了一个二部图,并证明了该图中存在完全匹配.然后,我们提出了一个替代的充分条件时,$a=1, h=0$的直接证明。我们后来扩展我们的技术来研究$a=2, h=0$的拓扑结构,并在这种情况下,可恢复的擦除模式的子集的特征。对于两个$a=1, 2$,我们的证明方法是统一的,即,通过构造列和行代码的生成矩阵的张量积$G_{\text{col}} \otimes G_{\text{row}}$,使得某些正方形子矩阵保持满秩。满秩条件证明诉诸匹配确定较早,也在擦除子模式的另一组匹配。

英文摘要:

Given a topology of local parity-check constraints, a maximally recoverable code (MRC) can correct all erasure patterns that are information-theoretically correctable. In a grid-like topology, there are $a$ local constraints in every column forming a column code, $b$ local constraints in every row forming a row code, and $h$ global constraints in an $(m \times n)$ grid of codeword. Recently, Gopalan et al. initiated the study of MRCs under grid-like topology, and derived a necessary and sufficient condition, termed as the regularity condition, for an erasure pattern to be recoverable when $a=1, h=0$. In this paper, we consider MRCs for product topology ($h=0$). First, we construct a certain bipartite graph based on the erasure pattern satisfying the regularity condition for product topology (any $a, b$, $h=0$) and show that there exists a complete matching in this graph. We then present an alternate direct proof of the sufficient condition when $a=1, h=0$. We later extend our technique to study the topology for $a=2, h=0$, and characterize a subset of recoverable erasure patterns in that case. For both $a=1, 2$, our method of proof is uniform, i.e., by constructing tensor product $G_{\text{col}} \otimes G_{\text{row}}$ of generator matrices of column and row codes such that certain square sub-matrices retain full rank. The full-rank condition is proved by resorting to the matching identified earlier and also another set of matchings in erasure sub-patterns.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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