On Reed-Solomon codes as outer codes in the Davey-MacKay construction for channels with insertions and deletions

Abstract

The Davey-MacKay (DM) construction is a concatenated coding scheme for channels which introduce insertion, deletion and substitution errors. The inner code recovers synchronization while the outer code corrects substitution errors due to imperfect synchronization from the inner decoder. In the original DM construction, nonbinary LDPC codes were used as the outer codes. We show that when the insertion and deletion probabilities are sufficiently small, using a q2-ary (q2 − 1, (q2 − 1)R) Reed-Solomon (RS) code in place of a q-ary (2(q2 − 1), 2(q2 − 1)R) LDPC code as the outer code in the DM construction along with an iterative soft-decision RS decoder, offers better frame-error-rate (FER) performance for moderate to high-rate applications involving relatively short blocklengths.