The pivotal storage density win achieved by solid-state devices over magnetic devices recently is a result of multiple innovations in physics, architecture, and signal processing. Constrained coding is used in Flash devices to increase reliability via mitigating inter-cell interference. Recently, capacity-achieving constrained codes were introduced to serve that purpose. While these codes result in minimal redundancy, they result in non-negligible complexity increase and access speed limitation since pages cannot be read separately. In this paper, we suggest new constrained coding schemes that have low-complexity and preserve the desirable high access speed in modern Flash devices. The idea is to eliminate error-prone patterns by coding data either only on the left-most page (binary coding) or only on the two left-most pages ($4$-ary coding) while leaving data on all the remaining pages uncoded. Our coding schemes are systematic and capacity-approaching. We refer to the proposed schemes as read-and-run (RR) constrained coding schemes. The $4$-ary RR coding scheme is introduced to limit the rate loss. We analyze the new RR coding schemes and discuss their impact on the probability of occurrence of different charge levels. We also demonstrate the performance improvement achieved via RR coding on a practical triple-level cell Flash device.

翻译：固态存储设备近期在存储密度上超越磁存储设备的关键优势，源于物理、架构和信号处理领域的多项创新。闪存设备采用约束编码技术，通过降低单元间干扰来提升可靠性。近年来，为达成该目标引入了容量可达的约束编码方案。尽管这些编码冗余度极低，但会导致不可忽视的复杂度增加及访问速度受限——因为页面无法独立读取。本文提出新型低复杂度约束编码方案，在保持现代闪存设备高速访问特性的同时消除易错模式。核心思路是通过仅在最左侧页面（二进制编码）或仅在最左侧两个页面（四进制编码）进行数据编码，其余页面保留原始数据。本编码方案具有系统性和逼近信道容量的特性，我们称之为“读取即运行”（RR）约束编码方案。为限制速率损失，进一步引入四进制RR编码方案。我们分析了新RR编码方案的性能，探讨了其对不同电荷级出现概率的影响，并在实际三层单元闪存设备上验证了RR编码带来的性能提升。