Improved Binary DAC Codec with Spectrum for Equiprobable Sources

Slepian-Wolf coding (SWC) can be effectively implemented by distributed arithmetic coding (DAC) codes. A theoretical tool named spectrum has been developed to analyze the complexity of the full-search binary DAC (BDAC) decoder for equiprobable sources. Following this work, this paper aims at improving the coding efficiency of BDAC codes. To achieve this goal, this paper analyzes how BDAC codes partition source space into codebooks and links codebook cardinalities with the initial spectrum. Further, by exploiting the final spectrum, this paper proves that the decoding error probability of BDAC codes will not tend to zero as code length goes to infinity, even at rates greater than the Slepian-Wolf limit. On the basis of theoretical analyses, two techniques are proposed to reduce the decoding error probability of BDAC codes, i.e., the permutation technique, which removes "near" (in the sense of Hamming distance) codewords in each codebook, and the weighted branching technique, which reduces the mis-pruning risk of proper paths during the decoding. The effectiveness of both techniques is well verified by experimental results.