The Experts below are selected from a list of 4788 Experts worldwide ranked by ideXlab platform
Vijay K. Bhargava - One of the best experts on this subject based on the ideXlab platform.
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A (105,10,47) binary quasi-cyclic code☆
Applied Mathematics Letters, 1995Co-Authors: T.a. Gulliver, Vijay K. BhargavaAbstract:A (105, 10, 47) binary quasi-cyclic code is presented which improves the known lower bound on the maximum possible minimum distance. The generator matrix is characterized in terms of m × m circulant matrices, where m = 5. This code is extended with an even Parity Check Bit to a (106, 10, 48) code which also improves the known bound. The weight distributions of these codes are presented.
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Two new rate 2/p binary quasi-cyclic codes
IEEE Transactions on Information Theory, 1994Co-Authors: T.a. Gulliver, Vijay K. BhargavaAbstract:A class of rate 2/P quasi-cyclic codes can be characterized in terms of m/spl times/m circulant matrices. In this correspondence, two new codes with parameters (80, 10, 35) and (95, 10, 42) are presented which improve the known lower bound on the maximum possible minimum distance. The former code can be extended with an even Parity Check Bit to an (81, 10, 36) code that establishes that d/sub 2/(81, 10)=36. >
T.a. Gulliver - One of the best experts on this subject based on the ideXlab platform.
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A (105,10,47) binary quasi-cyclic code☆
Applied Mathematics Letters, 1995Co-Authors: T.a. Gulliver, Vijay K. BhargavaAbstract:A (105, 10, 47) binary quasi-cyclic code is presented which improves the known lower bound on the maximum possible minimum distance. The generator matrix is characterized in terms of m × m circulant matrices, where m = 5. This code is extended with an even Parity Check Bit to a (106, 10, 48) code which also improves the known bound. The weight distributions of these codes are presented.
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Two new rate 2/p binary quasi-cyclic codes
IEEE Transactions on Information Theory, 1994Co-Authors: T.a. Gulliver, Vijay K. BhargavaAbstract:A class of rate 2/P quasi-cyclic codes can be characterized in terms of m/spl times/m circulant matrices. In this correspondence, two new codes with parameters (80, 10, 35) and (95, 10, 42) are presented which improve the known lower bound on the maximum possible minimum distance. The former code can be extended with an even Parity Check Bit to an (81, 10, 36) code that establishes that d/sub 2/(81, 10)=36. >
Jaeho Choi - One of the best experts on this subject based on the ideXlab platform.
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Pilot-assisted technique on LDPC-coded COFDM-CDMA in frequency-selective multipath fading channels
9th Asia-Pacific Conference on Communications (IEEE Cat. No.03EX732), 1Co-Authors: Tae-yoon Park, Youngshin Ahn, Ung Heo, Im-bin Lim, Jaeho ChoiAbstract:The low-density Parity-Check code is known for a superior signal reception capability in AWGN and/or flat fading channels with respect to increased encoding rates, however, its performance degrades when the communication channel becomes multipath fading. In this paper we have investigated a novel approach applying a pilot-assisted LDPC coding to a coded OFDM-CDMA system, which operates in a multipath fading mobile channel. In a typical multipath fading mobile channel with a SNR of 16 dB or lower, however, it is a challenging problem to obtain a BER lower than 1 out of I0/sup 5/ when the LDPC encoding rate is about 1/4. In order to enhance the performance of the proposed system we have improve the LDPC decoding algorithm by incorporating the pilot information with the Parity Check Bit. In contrast to the conventional 1/4-rate LDPC coded transmission symbol that is consisted of data Bits and Parity-Check Bits in 1 to 3 proportion, in the proposed method the same rate LDPC transmission symbol contains data Bits, Parity-Check Bits, and pilot Bits in 1 to 2 to 1 proportion, respectively. The included pilot Bits are effective not only for channel estimation and equalization but for LDPC symbol decoding by assisting the Parity-Check Bits. The proposed system performance has been verified using computer simulations in multipath, Rayleigh fading channels, and the results show us usefulness of the proposed method over the conventional LDPC coding methods in terms of SNR vs BER measurements.
Zhongfeng Wang - One of the best experts on this subject based on the ideXlab platform.
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ISCAS - A Novel Low-Complexity Joint Coding and Decoding Algorithm for NB-LDPC Codes
2019 IEEE International Symposium on Circuits and Systems (ISCAS), 2019Co-Authors: Suwen Song, Jing Tian, Jun Lin, Zhongfeng WangAbstract:Non-binary low-density Parity-Check (NB-LDPC) codes exhiBit a much better performance than their binary counterparts, especially for moderate codeword length and high-order modulation. However, their decoding algorithms suffer from very high computational complexity. In this paper, a low-complexity algorithm is proposed, named Parity-Check erased algorithm (PCEA), where an additional Parity Check Bit is added to each symbol of the codeword when encoding and a series of simple operations are performed based on these Bits during decoding. As a universal joint coding and decoding algorithm, the PCEA can be combined with arBitrary NB-LDPC encoding schemes and decoding algorithms based on message passing. The proposed algorithm facilitates significant improvement of decoding performance with a small decrease of the code rate. Additionally, it usually has an even better performance than a nearly same-rate code constructed by the original method, and requires much lower decoding complexity due to smaller size of the Parity Check matrix.
Chingyun Chang - One of the best experts on this subject based on the ideXlab platform.
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hiding data in Parity Check Bit
International Conference on Ubiquitous Information Management and Communication, 2010Co-Authors: Chishiang Chan, Chingyun ChangAbstract:In this paper, we propose a method to hide secret data in Parity Check Bits. In the data embedding phase, the method first takes 4 Bits from the cover data and 3 Bits from the secret data. The 3-Bit secret data are inserted into appropriate positions that represent the Parity Bits of the 4-Bit cover data to form a code word. The Matrix Coding is then used to select a specific Bit from the code word to modify so that the code word can satisfy the condition of (7, 4) Hamming code and the 4-Bit stego data can be obtained. If the selected Bit is a data Bit, it is directly modified. In this case, the three Parity Check Bits of the 4-Bit stego data are exactly the 3-Bit secret data. However, if the selected Bit is a Parity Check Bit of the code word, instead of modifying the Parity Check Bit, two cover data Bits are modified. In the data extracting phase, the 3-Bit secret data can be extracted by calculating Parity Check Bits of 4-Bit stego data. The experimental results show that the proposed method has achieved comparable embedding capacity, and the number of modified pixels is also satisfactory.
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ICUIMC - Hiding data in Parity Check Bit
Proceedings of the 4th International Conference on Uniquitous Information Management and Communication - ICUIMC '10, 2010Co-Authors: Chishiang Chan, Chingyun ChangAbstract:In this paper, we propose a method to hide secret data in Parity Check Bits. In the data embedding phase, the method first takes 4 Bits from the cover data and 3 Bits from the secret data. The 3-Bit secret data are inserted into appropriate positions that represent the Parity Bits of the 4-Bit cover data to form a code word. The Matrix Coding is then used to select a specific Bit from the code word to modify so that the code word can satisfy the condition of (7, 4) Hamming code and the 4-Bit stego data can be obtained. If the selected Bit is a data Bit, it is directly modified. In this case, the three Parity Check Bits of the 4-Bit stego data are exactly the 3-Bit secret data. However, if the selected Bit is a Parity Check Bit of the code word, instead of modifying the Parity Check Bit, two cover data Bits are modified. In the data extracting phase, the 3-Bit secret data can be extracted by calculating Parity Check Bits of 4-Bit stego data. The experimental results show that the proposed method has achieved comparable embedding capacity, and the number of modified pixels is also satisfactory.
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IEEE ICCI - Hiding secret in Parity Check Bits by applying XOR Function
9th IEEE International Conference on Cognitive Informatics (ICCI'10), 2010Co-Authors: Chishiang Chan, Chingyun ChangAbstract:In this paper, we propose a hybrid data hiding method to embed three secret Bits to four cover pixels. In the proposed method, a Hamming code word consists of three Parity Check Bits whose values are identical to three secret Bits and four data Bits whose values are derived by performing XOR Function on four cover pixels. In order to keep the Hamming code word satisfying the condition of (7, 4) Hamming Code, at most one cover pixel would be modified. If the modified Bit is a data Bit of the code word, it is directly modified, and three secret Bits can be embedded to the cover pixels successfully. However, if the modified Bit is a Parity Check Bit, namely the secret Bit, instead of modifying the Parity Check Bit, two cover pixels are needed to be modified while the proposed method only requires one Bit modification by adopting the XOR Function. Our hybrid method only need to modify one cover pixel by adding/subtracting its values to/from one, and two resultant Bits of XOR Function are able to be adjusted to the desired Bits. In this way, the number of modified pixels can be further reduced. The experimental results show that the number of pixels that undergo modification during the embedding phase is fewer by using the proposed method than using the other two related method in most cases.