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Sökning: L773:0018 9448 OR L773:0018 9448 > Naturvetenskap

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1.
  • Blom, Rolf (författare)
  • Bounds on key equivocation for simple substitution ciphers
  • 1979
  • Ingår i: IEEE Transactions on Information Theory. - : IEEE. - 0018-9448 .- 1557-9654. ; 25:1, s. 8-18
  • Tidskriftsartikel (refereegranskat)abstract
    • The equivocation of the key for a simple substitution cipher is upper and lower hounded, when the message source is memoryless. The hounds are shown to be exponentially tight. The results are compared with random ciphering. It is observed that the exponential behavior of the equivocation of the key is not determined by the redundancy in the message source, but by the symbol probabilities which are closest in a certain sense.
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2.
  • Grezet, Matthias, et al. (författare)
  • Alphabet-Dependent Bounds for Linear Locally Repairable Codes Based on Residual Codes
  • 2019
  • Ingår i: IEEE Transactions on Information Theory. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9448 .- 1557-9654. ; 65:10, s. 6089-6100
  • Tidskriftsartikel (refereegranskat)abstract
    • Locally repairable codes (LRCs) have gained significant interest for the design of large distributed storage systems as they allow a small number of erased nodes to be recovered by accessing only a few others. Several works have thus been carried out to understand the optimal rate-distance tradeoff, but only recently the size of the alphabet has been taken into account. In this paper, a novel definition of locality is proposed to keep track of the precise number of nodes required for a local repair when the repair sets do not yield MDS codes. Then, a new alphabet-dependent bound is derived, which applies both to the new definition and the initial definition of locality. The new bound is based on consecutive residual codes and intrinsically uses the Griesmer bound. A special case of the bound yields both the extension of the Cadambe-Mazumdar bound and the Singleton-type bound for codes with locality (r, delta), implying that the new bound is at least as good as these bounds. Furthermore, an upper bound on the asymptotic rate-distance tradeoff of LRCs is derived, and yields the tightest known upper bound for large relative minimum distances. Achievability results are also provided by deriving the locality of the family of Simplex codes together with a few examples of optimal codes.
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3.
  • Chen, Eric Zhi, 1963- (författare)
  • Further results on difference triangle sets
  • 1994
  • Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 40:4, s. 1268-1270
  • Tidskriftsartikel (refereegranskat)abstract
    • Further results on the upper bounds for difference tri8nglesets (DTS) are derived from disjoint difference sets and additive sequencesof permutations, whit3 greatly improve the known bounds.
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4.
  • Chen, Eric Zhi, 1963- (författare)
  • Six new binary quasi-cyclic codes
  • 1994
  • Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 40:5, s. 1666-1667
  • Tidskriftsartikel (refereegranskat)abstract
    • Six new quasi-cyclic codes are presented, which improve thelower bounds on the minimum distance for a binary code. A localexhaustive search is used to find these codes and many other quasi-cycliccodes which attain the lower bounds.
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5.
  • Dubrova, Elena (författare)
  • Finding Matching Initial States for Equivalent NLFSRs in the Fibonacci and the Galois Configurations
  • 2010
  • Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 56:6, s. 2961-2966
  • Tidskriftsartikel (refereegranskat)abstract
    • The Fibonacci and the Galois configurations of nonlinear feedback shift registers (NLFSRs) are considered. In the former, the feedback is applied to the input bit of the shift register only. In the latter, the feedback can potentially be applied to every bit. The sufficient conditions for equivalence of NLFSRs in the Fibonacci and the Galois configurations have been formulated previously. The equivalent NLFSRs in different configurations normally have to be initialized to different states to generate the same output sequences. The mapping between the initial states of two equivalent NLFSRs in the Fibonacci and the Galois configurations is derived in this paper.
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6.
  • Li, X. Y., et al. (författare)
  • Coverage Properties of the Target Area in Wireless Sensor Networks
  • 2012
  • Ingår i: Ieee Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 58:1, s. 430-437
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytical approximation is developed for the probability of sensing coverage in a wireless sensor network with randomly deployed sensor nodes each having an isotropic sensing area. This approximate probability is obtained by considering the properties of the geometric graph, in which an edge exists between any two vertices representing sensor nodes with overlapping sensing areas. The principal result is an approximation to the proportion of the sensing area that is covered by at least one sensing node, given the expected number of nodes per unit area in a two-dimensional Poisson process. The probability of a specified region being completely covered is also approximated. Simulation results corroborate the probabilistic analysis with low error, for any node density. The relationship between this approximation and noncoverage by the sensors is also examined. These results will have applications in planning and design tools for wireless sensor networks, and studies of coverage employing computational geometry.
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7.
  • Andersson, Joel, et al. (författare)
  • On the Theorem of Uniform Recovery of Random Sampling Matrices
  • 2014
  • Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 60:3, s. 1700-1710
  • Tidskriftsartikel (refereegranskat)abstract
    • We consider two theorems from the theory of compressive sensing. Mainly a theorem concerning uniform recovery of random sampling matrices, where the number of samples needed in order to recover an s-sparse signal from linear measurements (with high probability) is known to be m greater than or similar to s(ln s)(3) ln N. We present new and improved constants together with what we consider to be a more explicit proof. A proof that also allows for a slightly larger class of m x N-matrices, by considering what is called effective sparsity. We also present a condition on the so-called restricted isometry constants, delta s, ensuring sparse recovery via l(1)-minimization. We show that delta(2s) < 4/root 41 is sufficient and that this can be improved further to almost allow for a sufficient condition of the type delta(2s) < 2/3.
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8.
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9.
  • Friedland, S., et al. (författare)
  • The 1-vertex transfer matrix and accurate estimation of channel capacity
  • 2010
  • Ingår i: IEEE Transactions on Information Theory. - : IEEE. - 0018-9448 .- 1557-9654. ; 57:8, s. 3692-3699
  • Tidskriftsartikel (refereegranskat)abstract
    • The notion of a 1-vertex transfer matrix for multidimensional codes is introduced. It is shown that the capacity of such codes, or the topological entropy, can be expressed as the limit of the logarithm of spectral radii of 1-vertex transfer matrices. Storage and computations using the 1-vertex transfer matrix are much smaller than storage and computations needed for the standard transfer matrix. The method is applied to estimate the first 15 digits of the entropy of the 2-D (0, 1) run length limited channel. A large-scale computation of eigenvalues for the (0, 1) run length limited channel in 2-D and 3-D have been carried out. This was done in order to be able to compare the computational cost of the new method with the standard transfer matrix and have rigorous bounds to compare the estimates with. This in turn leads to improvements on the best previous lower and upper bounds for these channels.
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10.
  • Haasler, Isabel, et al. (författare)
  • Multi-Marginal Optimal Transport and Probabilistic Graphical Models
  • 2021
  • Ingår i: IEEE Transactions on Information Theory. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9448 .- 1557-9654. ; 67:7, s. 4647-4668
  • Tidskriftsartikel (refereegranskat)abstract
    • We study multi-marginal optimal transport problems from a probabilistic graphical model perspective. We point out an elegant connection between the two when the underlying cost for optimal transport allows a graph structure. In particular, an entropy regularized multi-marginal optimal transport is equivalent to a Bayesian marginal inference problem for probabilistic graphical models with the additional requirement that some of the marginal distributions are specified. This relation on the one hand extends the optimal transport as well as the probabilistic graphical model theories, and on the other hand leads to fast algorithms for multi-marginal optimal transport by leveraging the well-developed algorithms in Bayesian inference. Several numerical examples are provided to highlight the results.
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