几类near MDS码和最优局部修复码的构造

Several Constructions of Near MDS Codes and Optimal Locally Recoverable Codes

局部修复码是一种通过局部修复提高存储节点修复效率的重要编码方法,在分布式存储和云存储中有重要应用.本文首先构造了几类维数为4或5的near MDS(near Maximum Distance Separable)码,精确计算出了它们的参数和重量分布.特别地,得到了一些参数相同但重量分布不同的near MDS码.此外,通过确定near MDS码的局部度,得到了几类距离最优和维数最优的局部修复码.这些局部修复码的参数和文献中已知最优局部修复码的参数不同.

Locally recoverable codes offer an efficient way to improve the repair efficiency of storage nodes by local recovery.They are widely used in distributed storage and cloud storage.In this paper,we first present several constructions of near MDS(near maximum distance separable)codes of dimension 4 or 5.The parameters and weight distributions of the codes are explicitly determined.In particular,some families of near MDS codes with the same parameters but different weight distributions are derived.Then the locality of the near MDS codes is also studied.Several families of distance-opti⁃mal and dimension-optimal locally recoverable codes are obtained.These locally recoverable codes have different parame⁃ters from those of known ones in the literature.