The expected write deficiency of index-less flash codes and their improvement

The expected write deficiency of the index-less indexed flash codes (ILIFC) is studied, and a technique is developed to improve the write deficiency of ILIFC. ILIFC is a coding scheme for flash memory, and consists of two stages with different coding techniques. This study first clarify the average write deficiency of the first stage of ILIFC, and shows that omitting the second stage of ILIFC can be a practical option for realizing flash codes with good average performance. The study also investigates an improvement of the index-less coding which is used in the first stage of ILIFC. The improvement reduces the write deficiency of ILIFC, and relaxes the constraints on the rate of the code.