Browsing by Subject "Upper bound"
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Item Open Access Capacity bounds for the poisson-repeat channel(Institute of Electrical and Electronics Engineers, 2023-08-22) Kazemi, Mohammad; Duman, Tolga M.We develop bounds on the capacity of Poisson-repeat channels (PRCs) for which each input bit is independently repeated according to a Poisson distribution. The upper bounds are obtained by considering an auxiliary channel where the output lengths corresponding to input blocks of a given length are provided as side information at the receiver. Numerical results show that the resulting upper bounds are significantly tighter than the best known one for a large range of the PRC parameter ? (specifically, for ? =0.35). We also describe a way of obtaining capacity lower bounds using information rates of the auxiliary channel and the entropy rate of the provided side information.Item Open Access Dwell time optimization in switching control of parameter varying time delay systems(IEEE, 2011) Yan, P.; Özbay, Hitay; Şansal, M.It has been shown that parameter varying systems with time delays can be robustly stabilized by switching control, provided that the plant's parameter varies slowly enough such that the dwell time conditions of the switched controllers can be satisfied. In this paper, the minimization of dwell time is considered, where an iterative search algorithm is developed from the singular value perspectives. The local minimal dwell time obtained in this paper can be used to estimate the upper bound on how fast the plant's parameters can vary. Meanwhile, the switching controller synthesis with optimal dwell time is also discussed, where robust stabilizer design algorithm is presented to achieve robust stability at certain operating range, as well as the local minimal dwell time for controller switching. A numerical example is given to illustrate the proposed algorithm.Item Open Access An improved graph-entropy bound for perfect hashing(IEEE, 1994-06-07) Arıkan, ErdalGives an improved graph-entropy bound on the size of families of perfect hash functions. Examples are given illustrating that the new bound improves previous bounds in several instances.Item Open Access An information-theoretic analysis of Grover's algorithm(IEEE, 2003-06-07) Arıkan, ErdalGrover discovered a quantum algorithm for identifying a target element in an unstructured search universe of N items in approximately 1r/4VN queries to a quantum oracle. For classical search using a classical oracle, the search complexity is of order N /2 queries since on average half of the items must be searched. In work preceding Grover's, Bennett et al. had shown that no quantum algorithm can solve the search problem in fewer than D(VN) queries. Thus, Grover's algorithm has optimal order of complexity. Here, we present an informationtheoretic analysis of Grover's algorithm and show that the square-root speed-up by Grover's algorithm is the best possible by any algorithm using the same quantum oracle.Item Open Access Noise enhanced detection in multiple-access environments(IEEE, 2009) Bayram, Suat; Gezici, SinanUnder certain conditions, addition of noise can enhance performance of suboptimal detectors, which is called the stochastic resonance (SR) effect. In this paper, the effects of SR are investigated for conventional detectors in the presence of multiple-access interference. First, conditions under which probability of error performance of the detector can or cannot be improved are obtained. Then, performance of noise enhanced detectors are analyzed, and an upper bound on the amount of performance improvement that can be obtained via SR is derived. Numerical examples are presented to support the theoretical analysis.Item Open Access On the number of bins in equilibria for signaling games(IEEE, 2019-07) Sarıtaş, Serkan; Yüksel, Serdar; Gezici, SinanWe investigate the equilibrium behavior for the decentralized quadratic cheap talk problem in which an encoder and a decoder, viewed as two decision makers, have misaligned objective functions. In prior work, we have shown that the number of bins under any equilibrium has to be at most countable, generalizing a classical result due to Crawford and Sobel who considered sources with density supported on [0, 1]. In this paper, we refine this result in the context of exponential and Gaussian sources. For exponential sources, a relation between the upper bound on the number of bins and the misalignment in the objective functions is derived, the equilibrium costs are compared, and it is shown that there also exist equilibria with infinitely many bins under certain parametric assumptions. For Gaussian sources, it is shown that there exist equilibria with infinitely many bins.