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arXiv 1808.04539cs.ITcs.CCcs.DMmath.ITmath.NT
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利用函数域构造最大可恢复局部重构码

Constructions of maximally recoverable local reconstruction codes via function fields

Venkatesan Guruswami, Lingfei Jin, Chaoping Xing

摘要:

局部重构码(LRC)允许基于仅几个其它码字符号以局部方式从少量擦除恢复。最大可恢复(MR)LRC提供了这种局部和全局容错的最佳可能混合,保证从所有擦除模式中恢复,这些擦除模式在存在局部恢复组的情况下是信息理论上可校正的。在$(n,r,h,a)$ -LRC中,将$n$码字符号划分成$r$不相交组,每个不相交组包括能够局部校正$a$擦除的$a$局部奇偶校验。MR LRC最近受到了广泛的关注,许多显式的结构涵盖了不同的参数范围。不幸的是,所有已知的构造都需要在$h$或$a$中呈指数的大的场尺寸,并且感兴趣的是获得最小可能场尺寸的MR LRC。在这项工作中,我们开发了一种基于函数场的方法来构建MR LRC。我们的方法恢复,并在大多数参数制度改善,以前的方法的字段大小。例如,对于小$r \ll ε\log n$和大$h \ge Ω(n^{1-ε})$的情况,我们将字段大小从大致$n^h$改进为$n^{εh}$。对于$a=1$(一个局部奇偶校验)的情况下,我们提高了字段大小的平方从$r^{h(h+1)}$到$r^{h \lfloor (h+1)/2 \rfloor}$为一定范围的$r$。改进是适度的,但更重要的是通过一个有前途的新想法以统一的方式获得。

英文摘要:

Local Reconstruction Codes (LRCs) allow for recovery from a small number of erasures in a local manner based on just a few other codeword symbols. A maximally recoverable (MR) LRC offers the best possible blend of such local and global fault tolerance, guaranteeing recovery from all erasure patterns which are information-theoretically correctable given the presence of local recovery groups. In an $(n,r,h,a)$-LRC, the $n$ codeword symbols are partitioned into $r$ disjoint groups each of which include $a$ local parity checks capable of locally correcting $a$ erasures. MR LRCs have received much attention recently, with many explicit constructions covering different regimes of parameters. Unfortunately, all known constructions require a large field size that exponential in $h$ or $a$, and it is of interest to obtain MR LRCs of minimal possible field size. In this work, we develop an approach based on function fields to construct MR LRCs. Our method recovers, and in most parameter regimes improves, the field size of previous approaches. For instance, for the case of small $r \ll ε\log n$ and large $h \ge Ω(n^{1-ε})$, we improve the field size from roughly $n^h$ to $n^{εh}$. For the case of $a=1$ (one local parity check), we improve the field size quadratically from $r^{h(h+1)}$ to $r^{h \lfloor (h+1)/2 \rfloor}$ for some range of $r$. The improvements are modest, but more importantly are obtained in a unified manner via a promising new idea.

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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