In this study, we focus on delayed bit-interleaved coded modulation (DBICM). Unlike bit-interleaved coded modulation (BICM), DBICM can achieve the coded modulation (CM) capacity. The difference between DBICM and BICM lies in the transmission of multiple codewords. However, the decoding result of the previous codeword is used for the next decoding, so bad information may be fed back if the decoding fails, which leads to deterioration of the overall system. In the DBICM, common sequences, which are shared between the transmitter and the receiver, are used at the early and termination stages of transmission. By determining the common sequences and delay time slots, the DBICM capacity of the entire system can be specified. We show the common sequences and delay time slots of DBICM for the amplitude phase modulation and quadrature phase amplitude modulation to achieve CM capacity.

This study focuses on delayed bit-interleaved coded modulation (DBICM) for a two-dimensional signal constellation and shows that the capacity of DBICM is identical to the coded modulation capacity with less delay than before. An appropriate bit-labeling scheme based on Gray labeling for each signal point is also considered to prevent the performance degradation of DBICM. The results of the numerical calculations and simulations indicate that the proposed method improves performance.

Over the past two decades, irregular low-density parity-check (LDPC) codes have been hardly able to decode information corrupted by insertion and deletion (ID) errors without markers. Surprisingly, in this paper, we bring to light the existence of irregular LDPC codes that approach the theoretical limit of the channel with ID errors even without markers. These codes contain high fractions of low-degree check nodes that do not appear in irregular codes for other channels. This motivates us to investigate the contribution of low-degree check nodes to correcting ID errors. The investigation provides the following interesting result: degree-2 check nodes are critical to approaching the theoretical limit even without markers, codes with only degree-3, 4, or more check nodes provide moderate decoding performance, and codes with only degree-5 or more check nodes can hardly correct ID errors. Finally, we present simulation results that confirm the excellent decoding performance of the irregular codes without markers.

In this paper, the structured concatenated coding of protograph LDPC codes and markers for insertion and deletion channels are proposed, where the joint detector/decoder can deal with the differences in estimation accuracy of these errors. Conventional concatenated coding of LDPC codes and markers does not address the differences. The proposed approach with optimized protographs can exploit those differences and thus improve the performance of the joint detection/decoding. Iterative decoding thresholds and simulation results are provided to support the advantages of the proposed concatenated coding scheme.

In this study, we developed spatially coupled LDPC (SC-LDPC) codes on the two-dimensional array erasure (2DAE) channel. We propose a method of generating new SC-LDPC codes with the restriction on the check node constraint. We evaluate by density evolution analysis that the improvement of the threshold for the proposed two-dimensional SC-LDPC codes over the one-dimensional SC-LDPC codes. Moreover we verify that the BP threshold of the proposed codes can approach the corresponding maximum a posteriori (MAP) threshold of the original residual graph on the 2DAE channel.

In this paper, a new attack model in which the number of colluders are distributed according to a certain probability distribution is introduced. Two classes of collusion attacks which include well-known collusion attacks in the context of multimedia fingerprinting are provided. For these two attack classes, achievable rates for the unknown size of the actual colluders are derived. Based on the derived achievable rates, achieve rates for some particular attacks are investigated. For the AND attack, the bound derived in this paper coincides with the previous known bound, although the attack model in this paper does not assume that the decoder knows the actual number of colluders. Moreover, for the averaging attack, it is clarified that derived achievable rate is larger than previously known bound with random linear codes.

An iterative decoding algorithm of rate-compatible punctured low-density parity-check (RCP-LDPC) codes of high coding rates is developed. This algorithm performs a predetermined recovering process of punctured bits sums at the beginning of each iteration of the standard belief-propagation (BP) decoding algorithm. By propagating messages of two punctured bits sum, this algorithm can recover much more punctured bits than the standard BP decoding algorithm. It is shown that the proposed algorithm is applicable for RCP-LDPC codes of higher coding rates with little increase of decoding complexity.