New Constructions of Optimal Locally Repairable Codes with Super-Linear Length

As an important coding scheme in modern distributed storage systems, locally repairable codes (LRCs) have attracted a lot of attentions from perspectives of both practical applications and theoretical research. As a major topic in the research of LRCs, bounds and constructions of the corresponding optimal codes are of particular concerns. In this work, codes with $(r,delta)$-locality which have optimal minimal distance w.r.t. the bound given by Prakash et al. cite{Prakash2012Optimal} are considered. Through parity check matrix approach, constructions of both optimal $(r,delta)$-LRCs with all symbol locality ($(r,delta)_a$-LRCs) and optimal $(r,delta)$-LRCs with information locality ($(r,delta)_i$-LRCs) are provided. As a generalization of a work of Xing and Yuan cite{XY19}, these constructions are built on a connection between sparse hypergraphs and optimal $(r,delta)$-LRCs. With the help of constructions of large sparse hypergraphs, the length of codes constructed can be super-linear in the alphabet size. This improves upon previous constructions when the minimal distance of the code is at least $3delta+1$. As two applications, optimal H-LRCs with super-linear length and GSD codes with unbounded length are also constructed.