| 171. |
- Kuppinger, Patrick, et al.
(författare)
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Uncertainty Relations and Sparse Signal Recovery for Pairs of General Signal Sets
- 2012
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 58:1, s. 263 - 277
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Tidskriftsartikel (refereegranskat)abstract
- We present an uncertainty relation for the representation of signals in two different general (possibly redundant or incomplete) signal sets. Specifically, our results improve on the well-known (1+1/d)/2-threshold for dictionaries with coherence d by up to a factor of two. Furthermore, the new uncertainty relation is shown to lead to improved sparsity thresholds for recovery of signals that are sparse in general dictionaries. Furthermore, we provide probabilistic recovery guarantees for pairs of general dictionaries that also allow us to understand which parts of a general dictionary one needs to randomize over to ``weed out'' the sparsity patterns that prohibit breaking the square-root bottleneck.This uncertainty relation is relevant for the analysis of signals containing two distinct features each of which can be described sparsely in a suitable general signal set.
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| 172. |
- Kurri, Gowtham R., et al.
(författare)
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Multiple Access Channel Simulation
- 2022
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 68:11, s. 7575-7603
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Tidskriftsartikel (refereegranskat)
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| 173. |
- Lancho Serrano, Alejandro, 1991, et al.
(författare)
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On single-antenna Rayleigh block-fading channels at finite blocklength
- 2020
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 66:1, s. 496-519
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Tidskriftsartikel (refereegranskat)abstract
- This article concerns the maximum coding rate at which data can be transmitted over a noncoherent, single-antenna, Rayleigh block-fading channel using an error-correcting code of a given blocklength with a block-error probability not exceeding a given value. A high-SNR normal approximation of the maximum coding rate is presented that becomes accurate as the signal-to-noise ratio (SNR) and the number of coherence intervals $L$ over which we code tend to infinity. Numerical analyses suggest that the approximation is accurate at SNR values above 15dB and when the number of coherence intervals is 10 or more.
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| 174. |
- Lentmaier, Michael, et al.
(författare)
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An analysis of the block error probability performance of iterative decoding
- 2005
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 51:11, s. 3834-3855
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Tidskriftsartikel (refereegranskat)abstract
- Asymptotic iterative decoding performance is analyzed for several classes of iteratively decodable codes when the block length of the codes N and the number of iterations I go to infinity. Three classes of codes are considered. These are Gallager's regular low-density parity-check (LDPC) codes, Tanner's generalized LDPC (GLDPC) codes, and the turbo codes due to Berrou et al. It is proved that there exist codes in these classes and iterative decoding algorithms for these codes for which not only the bit error probability Pb, but also the block (frame) error probability PB, goes to zero as N and I go to infinity.
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| 175. |
- Lentmaier, Michael, et al.
(författare)
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Analytic expressions for the bit error probabilities of rate-1/2 memory 2 convolutional encoders
- 2004
-
Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 50:6, s. 1303-1311
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Tidskriftsartikel (refereegranskat)abstract
- Analytic expressions for the exact bit error probabilities of rate R = 1/2, memory m = 2 convolutional encoders are derived for a maximum-likelihood (ML) decoder and transmission over the binary-symmetric channel (BSC). The resulting expressions are rational functions of the crossover probability of the BSC. In addition to classical nonsystematic encoders without feedback, we consider also recursive systematic encoders which became especially important as component encoders in concatenated coding schemes. To attest the validity of the results, they are compared to computer simulations. Based on the presented technique also the bit error probability and the probability distribution of the output log-likelihood ratios of the Max-Log-MAP algorithm are derived in analytic form.
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| 176. |
- Lentmaier, Michael, et al.
(författare)
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Iterative decoding threshold analysis for LDPC convolutional codes
- 2010
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 56:10, s. 5274-5289
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Tidskriftsartikel (refereegranskat)abstract
- An iterative decoding threshold analysis for terminated regular LDPC convolutional (LDPCC) codes is presented. Using density evolution techniques, the convergence behavior of an iterative belief propagation decoder is analyzed for the binary erasure channel and the AWGN channel with binary inputs. It is shown that for a terminated LDPCC code ensemble, the thresholds are better than for corresponding regular and irregular LDPC block codes.
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| 177. |
- Li, X. Y., et al.
(författare)
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Coverage Properties of the Target Area in Wireless Sensor Networks
- 2012
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Ingår i: Ieee Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 58:1, s. 430-437
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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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| 178. |
- Lin, Hsuan Yin, et al.
(författare)
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Multi-Server Weakly-Private Information Retrieval
- 2022
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 68:2, s. 1197-1219
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Tidskriftsartikel (refereegranskat)abstract
- Private information retrieval (PIR) protocols ensure that a user can download a file from a database without revealing any information on the identity of the requested file to the servers storing the database. While existing protocols strictly impose that no information is leaked on the file’s identity, this work initiates the study of the tradeoffs that can be achieved by relaxing the perfect privacy requirement. We refer to such protocols as weakly-private information retrieval (WPIR) protocols. In particular, for the case of multiple noncolluding replicated servers, we study how the download rate, the upload cost, and the access complexity can be improved when relaxing the perfect privacy constraint. To quantify the information leakage on the requested file’s identity we consider mutual information (MI), worst-case information leakage, and maximal leakage (MaxL). We present two WPIR schemes, denoted by Scheme A and Scheme B, based on two recent PIR protocols and show that the download rate of the former can be optimized by solving a convex optimization problem. We also show that Scheme A achieves an improved download rate compared to the recently proposed scheme by Samy et al. under the so-called ϵ-privacy metric. Additionally, a family of schemes based on partitioning is presented. Moreover, we provide an information-theoretic converse bound for the maximum possible download rate for the MI and MaxL privacy metrics under a practical restriction on the alphabet size of queries and answers. For two servers and two files, the bound is tight under the MaxL metric, which settles the WPIR capacity in this particular case. Finally, we compare the performance of the proposed schemes and their gap to the converse bound.
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| 179. |
- Lin, Zihuai, 1967, et al.
(författare)
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On Joint Source and Channel Coding Using Trellis Coded CPM: Analytical Bounds on the Channel Distortion
- 2007
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 53:9, s. 3081-3094
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Tidskriftsartikel (refereegranskat)abstract
- Joint source and channel coding (JSCC) using trelliscoded quantization (TCQ) in conjunction with trellis coded continuous phase modulation (CPM) is studied. The channel is assumed to be the additive white gaussian noise (AWGN) channel. Analytical bounds on the channel distortion for the investigated systems with maximum-likelihood sequence detection (MLSD) are developed.The bounds are based on the transfer function technique,which was modified and generalized to include continuous-amplitude discrete-time signals. For a memoryless uniform source, the constructed bounds for the investigated systems are shown to be asymptotically tight for increasing channel signal-to-noise ratio (SNR) values. For a memoryless nonuniform source, the constructed bounds are not as tight as the one for the uniform source, however, it still can be used as an indication to how the systemperforms. It is concluded that the minimum Euclidean distance of the system alone is not enough to evaluate the performance of the considered systems. The number of error events having minimum Euclidean distance and the total distortion caused by those error events also affect the asymptotic performance. This work provides an analysis tool for the investigated systems. The analysis method is very general. It may be applied to any trellis based JSCC schemes.
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| 180. |
- Lindgren, Georg
(författare)
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On the shape and duration of FM clicks
- 1983
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 29:4, s. 536-543
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Tidskriftsartikel (refereegranskat)abstract
- The stochastic behavior of FM-clicks in an unmodulated carrier plus noise is studied in terms of the conditional behavior of stationary Gaussian processes after level crossings. By a systematic use of thc Slepian model processes it is shown that the normalized shape of a positive FM-click approaches a certain rational function with simple random coefficients as the carrier-to-noise ratio tends to infinity. The outcomes of this random function illustrate the typical click shapes that have been observed experimentally. The distribution of the duration of a click is studied by means of similar model processes, and its exact asymptotic density is derived. It is seen to be very similar to a Maxwell density, although of smaller order for large durations.
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