waashk/dblp huggingface dataset:
linear-codes-based lossless joint source-channel coding for multiple-access channels. a general lossless joint source-channel coding (jscc) scheme based on linear codes and random interleavers for multiple-access channels (macs) is presented and then analyzed in this paper. by the information-spectrum approach and the code-spectrum approach, it is shown that a linear code with a good joint spectrum can be used to establish limit-approaching lossless jscc schemes for correlated general sources and general macs, where the joint spectrum is a generalization of the input-output weight distribution. some properties of linear codes with good joint spectra are investigated. a formula on the "distance" property of linear codes with good joint spectra is derived, based on which, it is further proved that, the rate of any systematic codes with good joint spectra cannot be larger than the reciprocal of the corresponding alphabet cardinality, and any sparse generator matrices cannot yield linear codes with good joint spectra. the problem of designing arbitrary rate coding schemes is also discussed. a novel idea called "generalized puncturing" is proposed, which makes it possible that one good low-rate linear code is enough for the design of coding schemes with multiple rates. finally, various coding problems of macs are reviewed in a unified framework established by the code-spectrum approach, under which, criteria and candidates of good linear codes in terms of spectrum requirements for such problems are clearly presented.
performance of sigma-delta quantizations in finite frames. in this paper, we extend the results that we derived in [1], [2] to the case of filter banks (fbs) based transmission. we consider first- and second-order sigma-delta (sd) quantization in the context of an oversampled digital fourier transform (dft) fbs (dft-fbs). in this context, we investigate the case of odd-and even-stacked dft fbs. we establish the set of conditions that guarantee that the reconstruction minimum squares error (mse) behaves as 1/r2 where r denotes the frame redundancy and we derive the corresponding mse upper-bounds closed-form expressions. the obtained results demonstrate that overoversampled fbs that are subject to the first- and second-order sd can exhibit a reconstruction error behavior according to 1/r2. furthermore, the established results are shown to be true under the quantization model used in [3]-[6], as well as under the widely used additive white quantization noise assumption.
estimation of a regression function by maxima of minima of linear functions. in this paper, estimation of a regression function from independent and identically distributed random variables is considered. estimates are defined by minimization of the empirical l2 risk over a class of functions, which are defined as maxima of minima of linear functions. results concerning the rate of convergence of the estimates are derived. in particular, it is shown that for smooth regression functions satisfying the assumption of single index models, the estimate is able to achieve (up to some logarithmic factor) the corresponding optimal one-dimensional rate of convergence. hence, under these assumptions, the estimate is able to circumvent the so-called curse of dimensionality. the small sample behavior of the estimates is illustrated by applying them to simulated data.
analysis of a mixed strategy for multiple relay networks. infrastructure-based wireless communications systems as well as ad-hoc networks experience a growing importance in present-day telecommunications. an increased density and popularity of mobile terminals poses the question how to exploit wireless networks more efficiently. one possibility is to use relay nodes supporting the end-to-end communication of two nodes. in their landmark paper, cover and el gamal proposed different coding strategies for the single-relay channel. these strategies are the decode-and-forward and compress-and-forward approach, as well as a general lower bound on the capacity of a single-relay network which relies on the combined application of the previous two strategies. so far, only parts of their work-the decode-and-forward and the compress-and-forward strategy-have been applied to networks with multiple relays. in this paper a generalizing framework for multiple-relay networks is derived using a combined approach of partial decode-and-forward and the ideas of successive refinement with different side information. after describing the protocol structure, the achievable rates for the discrete memoryless relay channel as well as the gaussian multiple-relay channel are presented and analyzed. using these results the derived framework is compared with protocols of lower complexity, e.g., multilevel decode-and-forward and distributed compress-and-forward.
new optimal quadriphase sequences with larger linear span. in this paper, two new optimal families s and u of quadriphase sequences are presented. compared to the family a constructed by boztas et al. and the family d investigated by tang et al. respectively, the proposed families have the same optimal correlation properties and family size, but larger linear spans.
dynamic algorithms for multicast with intra-session network coding. the problem of multiple multicast sessions with intra-session network coding in time-varying networks is considered. the network-layer capacity region of input rates that can be stably supported is established. dynamic algorithms for multicast routing, network coding, power allocation, session scheduling, and rate allocation across correlated sources, which achieve stability for rates within the capacity region, are presented. this work builds on the back-pressure approach introduced by tassiulas et al., extending it to network coding and correlated sources. in the proposed algorithms, decisions on routing, network coding, and scheduling between different sessions at a node are made locally at each node based on virtual queues for different sinks. for correlated sources, the sinks locally determine and control transmission rates across the sources. the proposed approach yields a completely distributed algorithm for wired networks. in the wireless case, power control among different transmitters is centralized while routing, network coding, and scheduling between different sessions at a given node are distributed.
sinkhorn solves sudoku. the sudoku puzzle is a discrete constraint satisfaction problem, as is the error correction decoding problem. we propose here an algorithm for solution to the sinkhorn puzzle based on sinkhorn balancing. sinkhorn balancing is an algorithm for projecting a matrix onto the space of doubly stochastic matrices. the sinkhorn balancing solver is capable of solving all but the most difficult puzzles. a proof of convergence is presented, with some information theoretic connections. a random generalization of the sudoku puzzle is presented, for which the sinkhorn-based solver is also very effective.
on optimal quasi-orthogonal space-time block codes with minimum decoding complexity. orthogonal space-time block codes (ostbc) from orthogonal designs have both advantages of complex symbolwise maximum-likelihood (ml) decoding and full diversity. however, their symbol rates are upper bounded by 3/4 for more than two antennas for complex symbols. to increase the symbol rates, they have been generalized to quasi-orthogonal space-time block codes (qostbc) in the literature but the diversity order is reduced by half and the complex symbol-wise ml decoding is significantly increased to complex symbol pair-wise (pair of complex symbols) ml decoding. the qostbc has been modified by rotating half of the complex symbols for achieving the full diversity while maintaining the complex symbol pair-wise ml decoding. the optimal rotation angles for any signal constellation of any finite symbols located on both square lattices and equal-literal triangular lattices have been found by su-xia, where the optimality means the optimal diversity product (or product distance). qostbc has also been modified by yuen-guan-tjhung by rotating information symbols in another way such that it has full diversity and in the meantime it has real symbol pair-wise ml decoding (the same complexity as complex symbol-wise decoding) and the optimal rotation angle for square and rectangular qam constellations has been found. in this paper, we systematically study general linear transformations of information symbols for qostbc to have both full diversity and real symbol pair-wise ml decoding. we present the optimal transformation matrices (among all possible linear transformations not necessarily symbol rotations) of information symbols for qostbc with real symbol pair-wise ml decoding such that the optimal diversity product is achieved for both general square qam and general rectangular qam signal constellations. furthermore, our newly proposed optimal linear transformations for qostbc also work for general qam constellations in the sense that qostbc have full diversity with good diversity product property and real symbol pair-wise ml decoding. interestingly, the optimal diversity products for square qam constellations from the optimal linear transformations of information symbols found in this paper coincide with the ones presented by yuen-guan-tjhung by using their optimal rotations. however, the optimal diversity products for (nonsquare) rectangular qam constellations from the optimal linear transformations of information symbols found in this paper are better than the ones presented byyuen-guan-tjhung by using their optimal rotations. in this paper, we also present the optimal transformations for the co-ordinate interleaved orthogonal designs (ciod) proposed by khan-rajan for rectangular qam constellations.
construction methods for asymmetric and multiblock space-time codes. in this paper, the need for the construction of asymmetric and multiblock space-time codes is discussed. above the trivial puncturing method, i.e., switching off the extra layers in the symmetric multiple-input multiple-output (mimo) setting, two more sophisticated asymmetric construction methods are proposed. the first method, called the block diagonal method (bdm), can be converted to produce multiblock space-time codes that achieve the diversity-multiplexing tradeoff (dmt). it is also shown that maximizing the density of the newly proposed block diagonal asymmetric space-time (ast) codes is equivalent to minimizing the discriminant of a certain order, a result that also holds as such for the multiblock codes. an implicit lower bound for the density is provided and made explicit for an important special case that contains e.g., the systems equipped with 4tx +2rx antennas. further, an explicit scheme achieving the bound is given. another method proposed here is the smart puncturing method (spm) that generalizes the subfield construction method proposed in earlier work by hollanti and ranto and applies to any number of transmitting and lesser receiving antennas. the use of the general methods is demonstrated by building explicit, sphere decodable codes using different cyclic division algebras (cdas). computer simulations verify that the newly proposed methods can compete with the trivial puncturing method, and in some cases clearly outperform it. the conquering construction exploiting maximal orders improves upon the punctured perfect code and the djabba code as well as the icosian code. also extensive dmt analysis is provided.
reed-solomon and simplex codes for peak-to-average power ratio reduction in ofdm. new schemes for peak-to-average power ratio reduction in orthogonal frequency-division multiplexing (ofdm) systems are proposed. reed-solomon (rs) and simplex codes are employed to create a number of candidates, from which the best are selected. thereby, in contrast to existing approaches, the codes are arranged over a number of ofdm frames rather than over the carriers, hence a combination of the principles of multiple signal representation with selection (as done in selected mapping) and the use of channel coding is present. in particular, in multiple-antenna transmission, the proposed schemes do not cause any additional delay, but due to the utilization of the dimension space, additional gains can be achieved. moreover, the schemes are very flexible; due to the selection step, any criterion of optimality can be taken into account. besides multiple-antenna transmission, packet transmission is briefly considered, which, moreover, covers the appealing similarities with incremental redundancy check schemes in automatic repeat request (arq) applications and with decoding of codes transmitted over the erasure channel. the performance of the schemes is (using some approximations) derived analytically and is covered by numerical results that are in very good agreement with the theory. significant gains can be achieved with these very flexible and versatile methods.
performance bounds for nonbinary linear block codes over memoryless symmetric channels. the performance of nonbinary linear block codes is studied in this paper via the derivation of new upper bounds on the block error probability under maximum-likelihood (ml) decoding. the transmission of these codes is assumed to take place over a memoryless and symmetric channel. the new bounds, which are based on the gallager bounds and their variations, are applied to the gallager ensembles of nonbinary and regular low-density parity-check (ldpc) codes. these upper bounds are also compared with sphere-packing lower bounds. this study indicates that the new upper bounds are useful for the performance evaluation of coded communication systems which incorporate nonbinary coding techniques.
authentication over noisy channels. an authentication counterpart of wyner's study of the wiretap channel is developed in this work. more specifically, message authentication over noisy channels is studied while impersonation and substitution attacks are investigated for both single-and multiple-message scenarios. for each scenario, information-theoretic lower and upper bounds on the opponent's success, or cheating, probability are derived. remarkably, in both scenarios, the lower and upper bounds are shown to match, and hence, the fundamental limits on message authentication over noisy channels are fully characterized. the opponent's success probability is further shown to be smaller than that derived in the classical noiseless channel model. these results rely on a novel authentication scheme in which shared key information is used to provide simultaneous protection against both types of attacks. finally, message authentication for the case in which the source and receiver possess only correlated sequences is studied.
density evolution for nonbinary ldpc codes under gaussian approximation. this paper extends the work on density evolution for binary low-density parity-check (ldpc) codes with gaussian approximation to ldpc codes over gf (q). we first generalize the definition of channel symmetry for nonbinary inputs to include q-ary phase-shift keying (psk) modulated channels for prime q and binary-modulated channels for q that is a power of 2. for the well-defined q-ary-input symmetric-output channel, we prove that under the gaussian assumption, the density distribution for messages undergoing decoding is fully characterized by (q - 1) quantities. assuming uniform edge weights, we further show that the density of messages computed by the check node decoder (cnd) is fully defined by a single number. we then present the approximate density evolution for regular and irregular ldpc codes, and show that the (q - 1)-dimensional integration involved can be simplified using a dimensionality reduction algorithm for the important case of q = 2p. through application of approximate density evolution and linear programming, we optimize the degree distribution of ldpc codes over gf(3) and gf(4). the optimized irregular ldpc codes demonstrate performance close to the shannon capacity for long codewords. we also design gf (q) codes for high-order modulation by using the idea of a channel adapter. we find that codes designed in this fashion outperform those optimized specifically for the binary additive white gaussian noise (awgn) channel for a short codewords and a spectral efficiency of 2 bits per channel use (b/cu).
adaptive alternating minimization algorithms. the classical alternating minimization (or projection) algorithm has been successful in the context of solving optimization problems over two variables. the iterative nature and simplicity of the algorithm has led to its application in many areas such as signal processing, information theory, control, and finance. a general set of sufficient conditions for the convergence and correctness of the algorithm are known when the underlying problem parameters are fixed. in many practical situations, however, the underlying problem parameters are changing over time, and the use of an adaptive algorithm is more appropriate. in this paper, we study such an adaptive version of the alternating minimization algorithm. more precisely, we consider the impact of having a slowly time-varying domain over which the minimization takes place. as a main result of this paper, we provide a general set of sufficient conditions for the convergence and correctness of the adaptive algorithm. perhaps somewhat surprisingly, these conditions seem to be the minimal ones one would expect in such an adaptive setting. we present applications of our results to adaptive decomposition of mixtures, adaptive log-optimal portfolio selection, and adaptive filter design.
the weight distribution of some irreducible cyclic codes. irreducible cyclic codes have been an interesting subject of study for a long time. their weight distribution is known in only a few cases. in this paper, the weight distribution of the irreducible cyclic codes in a number of other cases is determined. the number of nonzero weights in the codes dealt with in this paper varies between one and four.
distinguishability of quantum states by separable operations. in this paper, we study the distinguishability of multipartite quantum states by separable operations. we first present a necessary and sufficient condition for a finite set of orthogonal quantum states to be distinguishable by separable operations. an analytical version of this condition is derived for the case of (d - 1) pure states, where d is the total dimension of the state space under consideration. a number of interesting consequences of this result are then carefully investigated. remarkably, we show there exists a large class of 2 ⊗ 2 separable operations not being realizable by local operations and classical communication. before our work, only a class of 3 ⊗ 3 nonlocal separable operations was known [bennett et al., phys. rev. a 59, 1070 (1999)]. we also show that any basis of the orthogonal complement of a multipartite pure state is indistinguishable by separable operations if and only if this state cannot be a superposition of one or two orthogonal product states, i.e., has an orthogonal schmidt number not less than three, thus generalize the recent work about indistinguishable bipartite subspaces [watrous, phys. rev. lett. 95, 080505 (2005)]. notably, we obtain an explicit construction of indistinguishable subspaces of dimension 7 (or 6) by considering a composite quantum system consisting of two qutrits (resp., three qubits), which is slightly better than the previously known indistinguishable bipartite subspace with dimension 8.
improvements on parameters of algebraic-geometry codes from hermitian curves. using the vladut-xing method, we refine a construction of xu to improve the parameters of algebraic-geometry codes based on hermitian curves. the parameters of these hermitian codes are arbitrarily close to the singleton bound, provided that the length of the code is sufficiently large. we also exhibit a class of hermitian codes over any finite field fq2(q > 2) with good parameters.
a note on limited-trial chase-like algorithms achieving bounded-distance decoding. for the decoding of a binary linear block code of minimal hamming distance d over additive white gaussian noise (awgn) channels, a soft-decision decoder achieves bounded-distance (bd) decoding if its squared error-correction radius is equal to d. a chase-like algorithm outputs the best (most likely) codeword in a list of candidates generated by a conventional algebraic binary decoder in a few trials. it is of interest to design chase-like algorithms that achieve bd decoding with as least trials as possible. in this paper, we show that chase-like algorithms can achieve bd decoding with only o(d1/2+ε trials for any given positive number ε.
error-correction of multidimensional bursts. we present several methods and constructions to generate binary codes for correction of a multidimensional cluster-error, whose shape can be a box-error, a lee sphere error, or an error with an arbitrary shape. our codes have very low redundancy, close to optimal, and a large range of parameters of arrays and clusters. our main results are summarized as follows. 1) a construction of two-dimensional codes capable to correct a rectangular-error with considerably more flexible parameters from previously known constructions. this construction is easily generalized for d dimensions. 2) a novel method based on d colorings of the d-dimensional space for constructing d-dimensional codes correcting a d-dimensional cluster-error of various shapes. 3) a transformation of the d-dimensional space into another d-dimensional space in a way that a d-dimensional lee sphere is transformed into a shape located in a d-dimensional box of a relatively small size. 4) applying the coloring method to correct more efficiently a two-dimensional error whose shape is a lee sphere. 5) a construction of d-dimensional codes capable to correct a d-dimensional cluster-error of size b in which the number of erroneous positions is relatively small compared to b. 6) we present a code which corrects a d-dimensional arbitrary cluster-error with relatively small redundancy.
capacity of a multiple-antenna fading channel with a quantized precoding matrix. given a multiple-input multiple-output (mimo) channel, feedback from the receiver can be used to specify a transmit precoding matrix, which selectively activates the strongest channel modes. here we analyze the performance of random vector quantization (rvq), in which the precoding matrix is selected from a random codebook containing independent, isotropically distributed entries.we assume that channel elements are independent and identically distributed (i.i.d.) and known to the receiver, which relays the optimal (rate-maximizing) precoder codebook index to the transmitter using b bits.we first derive the large system capacity of beamforming (rank-one precoding matrix) as a function of b, where large system refers to the limit as b and the number of transmit and receive antennas all go to infinity with fixed ratios. rvq for beamforming is asymptotically optimal, i.e., no other quantization scheme can achieve a larger asymptotic rate.we subsequently consider a precoding matrix with arbitrary rank, and approximate the asymptotic rvq performance with optimal and linear receivers (matched filter and minimum mean squared error (mmse)). numerical examples show that these approximations accurately predict the performance of finite-size systems of interest. given a target spectral efficiency, numerical examples show that the amount of feedback required by the linear mmse receiver is only slightly more than that required by the optimal receiver, whereas the matched filter can require significantly more feedback.