| 1. |
- Bocharova, Irina, et al.
(författare)
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Combinatorial Optimization for Improving QC LDPC codes performance
- 2013
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Ingår i: IEEE International Symposium on Information Theory (ISIT). - 2157-8095 .- 2157-8117. ; , s. 2651-2655
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Konferensbidrag (refereegranskat)abstract
- Techniques for searching for good quasi-cyclic (QC) LDPC block codes of short and moderate lengths which are suitable for practical purposes are studied. To facilitate implementations only codes whose parity-check matrices having bidiagonal structure of their submatrices and consequently having low encoding complexity are considered. The problem of finding QC LDPC codes with the near-optimum frame or bit error rate performance is split into two independent steps: searching for the near-optimum column degree distribution of the parity-check matrix together with the best base matrix for this degree distribution and searching for the near-optimum labeling of the chosen base matrix. Sets of parameters and criteria for both steps are introduced and discussed. They allow further reduction of the search complexity without significant loss of the search optimality. New QC LDPC block codes of various code rates are obtained and their BER and FER performances are compared with those of the LDPC block codes as well as the turbo codes defined in the IEEE 802.16 WiMAX standard.
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| 2. |
- Bocharova, Irina, et al.
(författare)
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Near maximum-likelihood decoding of Generalized LDPC and Woven graph codes
- 2013
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Ingår i: IEEE International Symposium on Information Theory (ISIT). - 2157-8117 .- 2157-8095. ; , s. 3005-3009
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Konferensbidrag (refereegranskat)abstract
- Relations between Generalized LDPC codes, nonbinary LDPC codes, and woven graph codes are considered. Focus is on rather short codes suitable, for example, for coding control signaling information in mobile communications. In particular, codes of lengths less than 200 bits are studied. Low-complexity near maximum-likelihood (ML) decoding for these classes of codes is introduced and analyzed. Frame error rate (FER) performance of the new decoding procedure is compared with the same performance of ML and belief propagation (BP) decoding. It is shown that unlike BP decoding whose performances are mainly governed by the girth of the Tanner graph the new decoding procedure has performances which significantly depend on the minimum distance and spectrum of the woven code. Short woven graph codes with large minimum distances are tabulated.
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| 3. |
- Mitchell, David G.M., et al.
(författare)
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On the Minimum Distance of Generalized Spatially Coupled LDPC Codes
- 2013
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Ingår i: IEEE International Symposium on Information Theory Proceedings (ISIT), 2013. - 2157-8117 .- 2157-8095. - 9781479904440 ; , s. 1874-1878
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Konferensbidrag (refereegranskat)abstract
- Families of generalized spatially-coupled low-density parity-check (GSC-LDPC) code ensembles can be formed by terminating protograph-based generalized LDPC convolutional (GLDPCC) codes. It has previously been shown that ensembles of GSC-LDPC codes constructed from a protograph have better iterative decoding thresholds than their block code counterparts, and that, for large termination lengths, their thresholds coincide with the maximum a-posteriori (MAP) decoding threshold of the underlying generalized LDPC block code ensemble. Here we show that, in addition to their excellent iterative decoding thresholds, ensembles of GSC-LDPC codes are asymptotically good and have large minimum distance growth rates.
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| 4. |
- Sen, Nevroz, et al.
(författare)
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Multiple access channel with various degrees of asymmetric state Information
- 2012
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Ingår i: IEEE International Symposium on Information Theory Proceedings (ISIT), 2012. - 2157-8095 .- 2157-8117. - 9781467325806 ; , s. 1697-1701
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of reliable communication over multiple-access channels (MAC) where the channel is driven by an independent and identically distributed state process and the encoders and the decoder are provided with various degrees of asymmetric (noisy or partial) channel state information (CSI). Namely, we provide a single letter characterization for the capacity region when the encoders have access to non-causal asymmetric partial CSI and the decoder has complete CSI. When the encoders observe asymmetric noisy CSI with asymmetric delays and the decoder observes complete CSI, we provide a single letter characterization for the capacity region. Finally, we consider a cooperative scenario with common and private messages, with noisy CSIT and complete CSIR and provide a single letter expression for the capacity region. For the cooperative scenario, we also note that as soon as the common message encoder does not have access to CSI, then for any noisy CSIT and CSIR setup it is possible to obtain a single letter characterization for the capacity region.
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| 5. |
- Stankovski, Paul, et al.
(författare)
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An Optimal Sampling Technique for Distinguishing Random S-boxes
- 2012
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Ingår i: Information Theory Proceedings (ISIT), 2012 IEEE International Symposium on. - 2157-8095 .- 2157-8117. - 9781467325806 - 9781467325783 ; , s. 846-850
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Konferensbidrag (refereegranskat)abstract
- The nonrandom behavior of the outputs of a random S-box can be exploited when constructing distinguishers for cryptographic primitives. Different methods of constructing samples from the outputs have been used in the literature. However, it has been unclear exactly how these methods differ and which method is optimal. We analyze four different sampling techniques. We prove that two of these sampling techniques result in dependent samples. We further show one sampling technique that is optimal in terms of error probabilities in the resulting distinguisher. However, this sampling technique is quite impractical as it requires very large storage. We further show a fourth sampling technique that is much more practical, and we prove that it is equivalent to the optimal one. We also show an improved algorithm for calculating the associated probability distributions that are required for the attack.
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| 6. |
- Afanassiev, Valentin, et al.
(författare)
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Fast authentication codes based on random polynomial residue classes
- 1997
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Ingår i: Proceedings 1997 IEEE International Symposium on Information Theory. - 2157-8095. - 0780339568 - 9780780339569 ; , s. 175-175
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Konferensbidrag (refereegranskat)abstract
- The verification of the authenticity of a text document or a datafile is one of the main applications of cryptographic techniques. A common used technique for this purpose is the application of a message authentication code (MAC). Usually the MAC computation has to be done in software. Based on the relationship between error-correcting codes and so-called families of almost universal hash functions, and the error-correcting codes using polynomial residue classes we describe an efficient procedure for a MAC computation which is much faster than the standard MAC constructions using MD5 or SHA and uses much less key bits than the fast MACs based on bucket hashing.
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| 7. |
- Agrell, Erik, 1965, et al.
(författare)
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Achieving the Shannon Limit with Probabilistically Shaped BICM
- 2012
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781467325806 ; , s. 2421-2425
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Konferensbidrag (refereegranskat)abstract
- Probabilistic shaping for bit-interleaved coded modulation (BICM) systems at low signal-to-noise ratio (SNR) is investigated. Using known results for BICM systems with a uniform input distribution, the combinations of input alphabet, input distribution, and binary labeling that achieve the Shannon limit -1.59 dB are fully characterized. It is found that a BICM system achieves the Shannon limit at low SNR if and only if it can be represented as a zero-mean linear projection of a hypercube, which is the same condition as for uniform input distributions. Hence, probabilistic shaping offers no extra degrees of freedom to optimize the low-SNR mutual information of BICM systems, in addition to what is provided by geometrical shaping.
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| 8. |
- Alvarado, Alex, 1982, et al.
(författare)
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High-SNR Asymptotics of Mutual Information for Discrete Constellations
- 2013
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781479904464 ; , s. 2274-2278
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Konferensbidrag (refereegranskat)abstract
- The high-signal-to-noise ratio (SNR) asymptotic behavior of the mutual information (MI) for discrete constellations over the scalar additive white Gaussian noise channel is studied. Exact asymptotic expressions for the MI for arbitrary one-dimensional constellations and input distributions are presented in the limit as the SNR tends to infinity. Using the relationship between the MI and the minimum mean-square error (MMSE), asymptotics of the MMSE are also developed. It is shown that for any input distribution, the MI and the MMSE have an asymptotic behavior proportional to a Gaussian Q-function, whose argument depends only on the minimum Euclidean distance of the constellation and the SNR. Closed-form expressions for the coefficients of these Q-functions are calculated.
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| 9. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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A novel rate allocation method for multilevel coded modulation
- 2010
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781424469604 ; , s. 1983-1987
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Konferensbidrag (refereegranskat)abstract
- We present a new rate allocation scheme for multilevelcoded modulation based on the minimization of the totalblock error rate (BLER). The proposed method uses affine codecomponents and hard decision multistage decoding. Exhaustivesearch for the rate allocation which minimizes the total BLERjustifies the near-optimum performance of the introduced methodin moderate to high SNRs. Compared to previous approaches thisnew rate allocation scheme can improve the performance of thesystem by 1 dB at BLER = 10−6 for 16-QAM with Ungerboeck setpartitioning. Interestingly, our results indicate that the optimumrate allocation is a function of the SNR. Finally, the performanceof some specific codes are evaluated by simulation and unionbounds to verify the theoretical results.
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| 10. |
- Bitouzé, Nicolas, et al.
(författare)
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Making WOM Codes Decodable using Short Synchronous WOM Codes
- 2012
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781467325790 ; , s. 1381-1385
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Konferensbidrag (refereegranskat)abstract
- While some write once memory (WOM) codes are inherently decodable, others require the added knowledge of the current generation in order to successfully decode the state of the memory. If there is no limit on the code length, n, a binary non-decodable t-write WOM code can be made decodable at an insignificant cost in terms of code rate by adding t - 1 cells to store the current generation after replicating the code enough times for the t - 1 cells to be of negligible weight. This justifies the research on non-decodable WOM codes. However, if n is bounded, the t - 1 additional cells may introduce a significant loss in terms of code rate. In this paper, we propose a new method to make non-decodable WOM codes decodable at a lower price when n is bounded. The main idea is to add cells that do not only store the current generation, but also additional data, by using a synchronous (t - 1)-write WOM code of length t - 1 or slightly above which does not contain the all-zero codeword. A bound on the rate of a simple family of synchronous WOM codes with n = t is given, as well as very short codes from this family. Better codes are then obtained by local manipulations of these codes. Finally, a construction of synchronous WOM codes with good properties is proposed to reach higher values of t.
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