Block (0, k) Codes Designed by Coded Bit Stuffing

Timing recovery in communication and storage systems requires the use of Run Length Limited (RLL) or (d,k) codes. A class of such codes is constructed by a method called coded bit stuffing. The proposed encoder does not change the main part of input data bits, and just places these bits into the code word "as is". The remaining small part of data bits is encoded into a set of short nonzero words called separators. The separators are placed between the uncoded subblock of data. Due to the nonzero nature of the separators, the coded bit stream concatenated from data sub blocks and separators always satisfies the k constraint. The uncoded part of data bits can be arbitrary permuted without nullifying the k constraint. This property of the presented codes is important when an RLL code is used in the channel with an iterative detection scheme requiring interleaving. Simulations show that the designed codes have very good suppression of error propagation.