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Showing result 1 - 5 of 6 swedish dissertations matching the above criteria.

  2. 1. Voronoi-Based Coding

    Author : Erik Agrell; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Voronoi diagram; linear block code; Gaussian channel; neighbor descent; nearest neighbor search algorithm; computational geometry; asymptotic theory; source coding; lattice; vector quantization; soft-decision decoding; index assignment; channel coding; complexity;

    Abstract : The performance of a digital communication system can generally be improved by increasing the number of variables being jointly coded. In this sense, it is desirable to have, e.g., higher-dimensional quantizers, longer channel codes, and more users in a multiple-access system. READ MORE

  4. 2. Modulation Optimization for Noncoherent Optical Systems

    Author : Johnny Karout; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Direct detection; noncoherent communications; lattice codes; mutual information; fiber-optical communications; intensity modula- tion; sphere packing.; infrared communications; free-space optical communications;

    Abstract : There has been a significant improvement in high-speed electronics and optical components over the past few years, and this is one of the key enabling factors for high data rate transmission. Moreover, multi- level modulation formats, which encode information onto the carrier’s amplitude and phase, are necessary to increase the spectral efficiency of communication systems. READ MORE

  5. 3. Signaling for Optical Intensity Channels

    Author : Johnny Karout; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; lattice codes; mutual information; intensity modulation; noncoherent communications; Direct detection; sphere packing.; infrared communications; free-space optical communications; fiber-optical communications;

    Abstract : With the growing popularity of social media services, e-commerce, and many other internet-based services, we are witnessing a rapid growth in the deployment of data centers and cloud computing platforms. As a result, the telecommunications industry has to continue providing additional network capacity to meet the increasing demand for bandwidth. READ MORE

  6. 4. Some Notes on Post-Quantum Cryptanalysis

    Author : Erik Mårtensson; Institutionen för elektro- och informationsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cryptography; Post-quantum cryptography; LWE; BKW; Cryptanalysis; Lattice sieving; SVP; Lattice-based cryptography; Code-based cryptography;

    Abstract : Cryptography as it is used today relies on a foundational level on the assumptionthat either the Integer Factoring Problem (IFP) or the DiscreteLogarithm Problem (DLP) is computationally intractable. In the 1990s PeterShor developed a quantum algorithm that solves both problems in polynomialtime. READ MORE

  7. 5. Uncertainty and sensitivity analysis applied to LWR neutronic and thermal-hydraulic calculations

    Author : Augusto Hernandéz Solís; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sensitivity analysis; Nuclear best estimate codes; uncertainty analysis;

    Abstract : The deterministic modeling of LWRs begins with the computation of energy‐collapsed and homogenizedmacroscopic cross‐sections by means of a lattice code. Once these parameters are functionalized as a functionof the reactor state variables and discretized in space, they are used as input variables by core simulators inorder to calculate the spatial distribution of the neutron flux and thus, the spatial distribution of the power. READ MORE