Layered Index-less Indexed Flash Codes for improving average performance

In this paper, a modified Index-Less Indexed Flash Codes (ILIFC) for flash memory storage system is presented. Although, the ILIFC proposed by Mahdavifar et al. has excellent worst case performance, the ILIFC can be further improved in terms of average case performance. The proposed scheme, called layered-ILIFC, is based on the original ILIFC but our main focus is on the average case performance. It includes an idea of layer-coding for representing indices of information bits. The layer coding promotes uniform use of cells, which leads to better average case performance. In addition, it is shown that the average number of rewritings can be derived by using a Markov chain model. From some experiments, it is observed that the proposed scheme achieves larger average number of rewritings than that of the ILIFC without deterioration of the worst case performance.