| 1. |
- Agrell, Erik, 1965, et al.
(författare)
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Constant-weight code bounds from spherical code bounds
- 2000
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Ingår i: Proc. IEEE International Symposium on Information, Sorrento, Italy. - 0780358570 ; , s. 391-
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Konferensbidrag (refereegranskat)abstract
- We present new upper bounds on the size of constant-weight binary codes, derived from bounds for spherical codes. In particular, we improve upon the 1982 Johnson bound and the linear programming bound for constant-weight codes.
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| 2. |
- Bocharova, Irina, et al.
(författare)
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Searching for tailbiting codes with large minimum distances
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 341-341
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Konferensbidrag (refereegranskat)abstract
- Tailbiting trellis representations of linear block codes with an arbitrary sectionalization of the time axis are studied. A new lower bound on the maximal state complexity of an arbitrary tailbiting code is derived. The asymptotic behavior of the derived bound is investigated. Some new tailbiting representations for linear block codes of rates R=1/c, c=2,3,4 are presented
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| 3. |
- Engdahl, Karin, et al.
(författare)
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Analytical approach to low-density convolutional codes
- 2000
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Ingår i: [Host publication title missing]. - 0780358570
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Konferensbidrag (refereegranskat)abstract
- A statistical analysis of low-density convolutional (LDC) codes is performed. This analysis is based on the consideration of a special statistical ensemble of Markov scramblers and the solution to a system of recurrent equations describing this ensemble. The results of the analysis are lower bounds for the free distance of the codes and upper bounds for the maximum likelihood decoding error probability. For the case where the size of the scrambler tends to infinity some asymptotic bounds for the free distance and the error probability are derived. Simulation results for iterative decoding of LDC codes are also presented.
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| 4. |
- Johannesson, Rolf, et al.
(författare)
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On the decoding bit error probability for binary convolutional codes
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 398-398
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Konferensbidrag (refereegranskat)abstract
- An explanation is given for the paradoxical fact that, at low signal-to-noise ratios, the systematic feedback encoder results in fewer decoding bit errors than does a nonsystematic feedforward encoder for the same code. The analysis identifies a new code property, the d-distance weight density of the code. For a given d-distance weight density, the decoding bit error probability depends on the number of taps in the realization of the encoder inverse. Among all encoders for a given convolutional code, the systematic one has the simplest encoder inverse and, hence, gives the smallest bit error probability
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| 5. |
- Johansson, Thomas, et al.
(författare)
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A construction of resilient functions with high nonlinearity
- 2000
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Ingår i: IEEE International Symposium on Information Theory, 2000. Proceedings.. - 2157-8095. - 0780358570 ; , s. 184-184, s. 14-14
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Konferensbidrag (refereegranskat)abstract
- We propose a construction of resilient functions with n binary input variables and m binary output variables. In certain cases, the nonlinearity of these functions is the highest nonlinearity known.
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| 6. |
- Johansson, Thomas, et al.
(författare)
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Theoretical analysis of a correlation attack based on convolutional codes
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 212-212
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Konferensbidrag (refereegranskat)abstract
- The authors consider a binary synchronous stream cipher where a correlation has been identified between the keystream sequence and the output from one of the linear feedback shift registers (LFSR). They present a theoretical analysis of their recent algorithm for fast correlation attacks, based on the use of convolutional codes (see Advances in Cryptology - EUROCRYPT'99, Lecture Notes in Computer Science, vol.1592, p.347-62, Springer-Verlag, 1999).
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| 7. |
- Jordan, Ralph, et al.
(författare)
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Decoding of woven convolutional codes and simulation results
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 96-96
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Konferensbidrag (refereegranskat)abstract
- An iterative decoding scheme for woven convolutional codes is presented. It is called pipeline decoding and operates in a window sliding over the received sequence. This exploits the nature of convolutional codes as sequences and suits the concept of convolutional encoding and decoding as a continuous process. The pipeline decoder is analyzed in terms of decoding delay and decoding complexity. Additional interleaving for woven convolutional constructions is introduced by employing a convolutional scrambler. It is shown that some types of interleaving preserve the lower bound on the free distance of the original woven construction. Simulation results for woven convolutional codes are presented
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| 8. |
- Ståhl, Per, et al.
(författare)
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The effect of the tailbiting restriction on feedback encoders
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 343-343
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Konferensbidrag (refereegranskat)abstract
- It is shown that, for short and moderate relative tailbiting lengths and high signal-to-noise ratios, systematic feedback encoders have better bit error performance than nonsystematic feedforward encoders. Conditions for when tailbiting will fail are given and it is described how the encoder starting state can be obtained for feedback encoders in both controller and observer canonical form
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