Improved Constructions and Lower Bounds for Maximally Recoverable Grid Codes

In this paper, we continue the study of Maximally Recoverable (MR) Grid Codes initiated by Gopalan et al. [SODA 2017]. More precisely, we study codes over an $m\times n$ grid topology with one parity check per row and column of the grid along with $h\ge 1$ global parity checks. Previous works have largely focused on the setting in which $m=n$, where explicit constructions require field size which is exponential in $n$. Motivated by practical applications, we consider the regime in which $m,h$ are constants and $n$ is growing. In this setting, we provide a number of new explicit constructions whose field size is polynomial in $n$. We further complement these results with new field size lower bounds.