Insertion/deletion/substitution error correction using adaptive inversion of synchronization marker

This paper proposes an adaptive inversion method of synchronization marker to design efficient insertion/deletion/substitution error correcting code. Unlike the conventional marker coding in which marker patterns are selected deterministically, the proposed method selects marker patterns adaptively. That is, the first bit and the last bit of each marker are conditionally inverted depending on the neighboring δ bits of an LDPC codeword, where δ is a shift resistance of the marker. This paper also shows a forward-backward algorithm to calculate the symbol-by-symbol likelihood of the adaptive marker coding. Evaluation shows that the adaptive marker coding reduces the bit error rate. For deletion/insertion error probability P_i = P_d = 0.01, substitution error probability P_s = 0.01, and code rate 0.44, the decoded BER of conventional coding is 9.29 × 10^-4, while that of the proposed coding is 2.67 × 10^-4.