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Recovery Bounds on Class-Based Optimal Transport: A Sum-of-Norms Regularization Framework

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arXiv 2019年

作者： Rahbar, Arman Panahi, Ashkan Chehreghani, Morteza Haghir Dubhashi, Devdatt Krim, Hamid Department of Computer Science and Engineering Chalmers University of Technology GothenburgSE-412 96 Sweden Electrical and Computer Engineering Department North Carolina State University RaleighNC27606 United States

We develop a novel theoretical framework for understating OT schemes respecting a class structure. For this purpose, we propose a convex OT program with a sum-of-norms regularization term, which provably recovers the underlying class structure under geometric assumptions. Furthermore, we derive an accelerated proximal algorithm with a closed-form projection and proximal operator scheme, thereby affording a more scalable algorithm for computing optimal transport plans. We provide a novel argument for the uniqueness of the optimum even in the absence of strong convexity. Our experiments show that the new regularizer not only results in a better preservation of the class structure in the data but also yields additional robustness to the data geometry, compared to previous regularizers. Copyright © 2019, The Authors. All rights reserved.

关键词： Machine learning

Learning physical-layer communication with quantized feedback

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arXiv 2019年

作者： Song, Jinxiang Peng, Bile Häger, Christian Wymeersch, Henk Sahai, Anant Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Department of Electrical and Computer Engineering Duke University Durham United States Department of Electrical Engineering and Computer Science UC Berkeley Berkeley United States

Data-driven optimization of transmitters and receivers can reveal new modulation and detection schemes and enable physical-layer communication over unknown channels. Previous work has shown that practical implementations of this approach require a feedback signal from the receiver to the transmitter. In this paper, we study the impact of quantized feedback on data-driven learning of physical-layer communication. A novel quantization method is proposed, which exploits the specific properties of the feedback signal and is suitable for nonstationary signal distributions. The method is evaluated for linear and nonlinear channels. Simulation results show that feedback quantization does not appreciably affect the learning process and can lead to similar performance as compared to the case where unquantized feedback is used for training, even with 1-bit quantization. In addition, it is shown that learning is surprisingly robust to noisy feedback where random bit flips are applied to the quantization bits. Copyright © 2019, The Authors. All rights reserved.

关键词： Transmitters

Scoring the terabit/s goal: Broadband connectivity in 6G

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arXiv 2020年

作者： Rajatheva, Nandana Atzeni, Italo Bicaïs, Simon Björnson, Emil Bourdoux, André Buzzi, Stefano D'Andrea, Carmen Doré, Jean-Baptiste Erkucuk, Serhat Fuentes, Manuel Guan, Ke Hu, Yuzhou Huang, Xiaojing Hulkkonen, Jari Jornet, Josep Miquel Katz, Marcos Makki, Behrooz Nilsson, Rickard Panayirci, Erdal Rabie, Khaled Rajapaksha, Nuwanthika Salehi, Mohammadjavad Sarieddeen, Hadi Shahabuddin, Shahriar Svensson, Tommy Tervo, Oskari Tölli, Antti Wu, Qingqing Xu, Wen Centre for Wireless Communications University of Oulu Finland CEA-Leti France KTH Royal Institute of Technology Sweden Linköping University Sweden IMEC Belgium University of Cassino and Southern Latium Italy Italy Department of Electrical and Electronics Engineering Kadir Has University Turkey Fivecomm Valencia Spain State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University China The Beijing Engineering Research Center of High-Speed Railway Broadband Mobile Communications China Algorithm Department ZTE Corporation China School of Electrical and Data Engineering Faculty of Engineering and Information Technology University of Technology Sydney Australia Nokia Bell Labs Finland Institute for the Wireless Internet of Things Department of Electrical and Computer Engineering Northeastern University United States Ericsson Research Gothenburg Sweden Department of Computer Science Electrical and Space Engineering Luleå University of Technology Sweden Department of Engineering Manchester Metropolitan University United Kingdom Division of Computer Electrical and Mathematical Sciences and Engineering King Abdullah University of Science and Technology Saudi Arabia Nokia Finland Department of Electrical Engineering Chalmers University of Technology Sweden State Key Laboratory of Internet of Things for Smart City Department of Electrical and Computer Engineering University of Macau China Huawei Technologies Germany

This paper explores the road to vastly improving the broadband connectivity in future 6G wireless systems. Different categories of use cases are considered, with peak data rates up to 1 Tbps. Several categories of enablers at the infrastructure, spectrum, and protocol/algorithmic levels are required to realize the intended broadband connectivity goals in 6G. At the infrastructure level, we consider ultra-massive MIMO technology (possibly implemented using holographic radio), intelligent reflecting surfaces, user-centric cell-free networking, integrated access and backhaul, and integrated space and terrestrial networks. At the spectrum level, the network must seamlessly utilize sub-6 GHz bands for coverage and spatial multiplexing of many devices, while higher bands will be mainly used for pushing the peak rates of point-to-point links. Finally, at the protocol/algorithmic level, the enablers include improved coding, modulation, and waveforms to achieve lower latency, higher reliability, and reduced complexity. © 2020, CC BY.

关键词： MIMO systems

Security of the Internet of Things: Vulnerabilities, Attacks and Countermeasures

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arXiv 2019年

作者： Butun, Ismail Österberg, Patrik Song, Houbing Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden Mid Sweden University Sundsvall Sweden Department of Electrical Computer Software and Systems Engineering Embry-Riddle Aeronautical University FL United States

Wireless Sensor Networks (WSNs) constitute one of the most promising third-millennium technologies and have wide range of applications in our surrounding environment. The reason behind the vast adoption of WSNs in various applications is that they have tremendously appealing features, e.g., low production cost, low installation cost, unattended network operation, autonomous and longtime operation. WSNs have started to merge with the Internet of Things (IoT) through the introduction of Internet access capability in sensor nodes and sensing ability in Internet-connected devices. Thereby, the IoT is providing access to huge amount of data, collected by the WSNs, over the Internet. However, owing to the absence of a physical line-of-defense, i.e. there is no dedicated infrastructure such as gateways to watch and observe the flowing information in the network, security of WSNs along with IoT is of a big concern to the scientific community. More specifically, for the application areas in which CIA (confidentiality, integrity, availability) has prime importance, WSNs and emerging IoT technology might constitute an open avenue for the attackers. Besides, recent integration and collaboration of WSNs with IoT will open new challenges and problems in terms of security. Hence, this would be a nightmare for the individuals using these systems as well as the security administrators who are managing those networks. Therefore, a detailed review of security attacks towards WSNs and IoT, along with the techniques for prevention, detection, and mitigation of those attacks are provided in this paper. In this text, attacks are categorized and treated into mainly two parts, most or all types of attacks towards WSNs and IoT are investigated under that umbrella: "Passive Attacks" and "Active Attacks". Understanding these attacks and their associated defense mechanisms will help paving a secure path towards the proliferation and public acceptance of IoT technology. Copyright © 2019, The Aut

关键词： Internet of things

Spatio-temporal modelling of wind speed variations 28

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Spatio-temporal modelling of wind speed variations

28th International Ocean and Polar engineering Conference, ISOPE 2018

作者： Mao, Wengang Ivarsson, Oscar Rychlik, Igor Department of Mechanics and Maritime Science China Department of Computer Science and Engineering China Department of Mathematical Sciences Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781880653876

Wind speed variability in the Northern North Atlantic has been successfully modelled by a spatio-temporal transformed Gaussian field in our previous study. It was shown that this type of model does not describe correctly the extreme wind speeds attributed to tropical storms and hurricanes. This spatio-temporal model was generalized to include the possibility of the occurrence of rare severe storms. In that work, the daily wind speed variability was modelled by the transformed Gaussian field, and then random components were added to model rare events with extreme wind speeds. The model was termed the hybrid model. The transformed Gaussian and the hybrid models are locally stationary and homogeneous random fields with localized dependence structure, which is described by time and space dependent parameters with a natural physical interpretation. In the present study, these models are used to describe the variability of wind speed in other areas, i.e., the Caribbean sea, the South China Sea and the Arctic area. In most locations, the transformed Gaussian field is a sufficiently accurate model. However, in some regions, e.g. Laptev and the Beaufort Sea at the Arctic, this model severely underestimates the frequencies of extreme winds. In this study, the hybrid model is used to describe the wind variation in these regions. There are also locations, e.g. along the east coast of Greenland, most of the coast areas of the South China Sea, where frequencies of high wind speeds are severely overestimated by the transformed Gaussian model. In this paper, the models are fitted to ERA-Interim reanalysis wind data and used to find long-term distributions of wind speed, to estimate wind speed return values, e.g. 100-year extreme wind speed, and to compute the expected yearly frequency of events that wind speed exceeds a fixed threshold value. Copyright © 2018 by the International Society of Offshore and Polar Engineers (ISOPE)

关键词： Speed

Privacy of Real-Time Pricing in Smart Grid

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Privacy of Real-Time Pricing in Smart Grid

IEEE Annual Conference on Decision and Control

作者： Mahrokh GhoddousiBoroujeni Dominik Fay Christos Dimitrakakis Maryam Kamgarpour Department of Electrical Engineering Sharif University of Technology Iran EECS school KTH Royal Institute of Technology Sweden Computer Science and Engineering faculty Chalmers University of Technology Sweden Automatic Control Laboratory ETH Zurich Switzerland

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

Installing smart meters to publish real-time electricity rates has been controversial while it might lead to privacy concerns. Dispatched rates include fine-grained data on aggregate electricity consumption in a zone and could potentially be used to infer a household's pattern of energy use or its occupancy. In this paper, we propose Blowfish privacy to protect the occupancy state of the houses connected to a smart grid. First, we introduce a Markov model of the relationship between electricity rate and electricity consumption. Next, we develop an algorithm that perturbs electricity rates before publishing them to ensure users' privacy. Last, the proposed algorithm is tested on data inspired by household occupancy models and its performance is compared to an alternative solution.

关键词： Hidden Markov models Privacy Data models Real-time systems Data privacy Pricing Smart grids

Quantum approximate optimization of the exact-cover problem on a superconducting quantum processor

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arXiv 2019年

作者： Bengtsson, Andreas Vikstål, Pontus Warren, Christopher Svensson, Marika Gu, Xiu Kockum, Anton Frisk Krantz, Philip Križan, Christian Shiri, Daryoush Svensson, Ida-Maria Tancredi, Giovanna Johansson, Göran Delsing, Per Ferrini, Giulia Bylander, Jonas Microtechnology and Nanoscience Chalmers University of Technology GöteborgSE-412 96 Sweden Computer Science and Engineering Chalmers University of Technology GöteborgSE-412 96 Sweden Jeppesen GöteborgSE-411 03 Sweden

Present-day, noisy, small or intermediate-scale quantum processors-although far from fault-tolerant-support the execution of heuristic quantum algorithms, which might enable a quantum advantage, for example, when applied to combinatorial optimization problems. On small-scale quantum processors, validations of such algorithms serve as important technology demonstrators. We implement the quantum approximate optimization algorithm (QAOA) on our hardware platform, consisting of two transmon qubits and one parametrically modulated coupler. We solve small instances of the NP-complete exact-cover problem, with 96.6% success probability, by iterating the algorithm up to level two. Copyright © 2019, The Authors. All rights reserved.

关键词： Heuristic algorithms

Incremental visual-inertial 3D mesh generation with structural regularities

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arXiv 2019年

作者： Rosinol, Antoni Sattler, Torsten Pollefeys, Marc Carlone, Luca Massachusetts Institute of Technology Cambridge MA United States Department of Electrical Engineering Chalmers University of Technology Sweden Department of Computer Science ETH Zürich Microsoft Switzerland

Visual-Inertial Odometry (VIO) algorithms typically rely on a point cloud representation of the scene that does not model the topology of the environment. A 3D mesh instead offers a richer, yet lightweight, model. Nevertheless, building a 3D mesh out of the sparse and noisy 3D landmarks triangulated by a VIO algorithm often results in a mesh that does not fit the real scene. In order to regularize the mesh, previous approaches decouple state estimation from the 3D mesh regularization step, and either limit the 3D mesh to the current frame [1], [2] or let the mesh grow indefinitely [3], [4]. We propose instead to tightly couple mesh regularization and state estimation by detecting and enforcing structural regularities in a novel factor-graph formulation. We also propose to incrementally build the mesh by restricting its extent to the time-horizon of the VIO optimization;the resulting 3D mesh covers a larger portion of the scene than a per-frame approach while its memory usage and computational complexity remain bounded. We show that our approach successfully regularizes the mesh, while improving localization accuracy, when structural regularities are present, and remains operational in scenes without regularities. Copyright © 2019, The Authors. All rights reserved.

关键词： State estimation

A monitoring campaign (2013-2020) of ESA’s Mars Express to study interplanetary plasma scintillation

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arXiv 2023年

作者： Kummamuru, P. Calvés, G. Molera Cimò, G. Pogrebenko, S.V. Bocanegra-Bahamón, T.M. Duev, D.A. Said, M.D. Edwards, J. Ma, M. Quick, J. Neidhardt, A. de Vicente, P. Haas, R. Kallunki, J. Maccaferri, G. Colucci, G. Yang, W.J. Hao, L.F. Weston, S. Kharinov, M.A. Mikhailov, A.G. Jung, T. School of Natural Sciences University of Tasmania Private Bag 37 HobartTAS7005 Australia Joint Institute for VLBI-European Research Infrastructure Consortium Oude Hogeveendijk 4 PD Dwingeloo7991 Netherlands Jet Propulsion Laboratory PasadenaCA United States California Institute of Technology PasadenaCA United States Shanghai Astronomical Observatory 80 Nandan Road Shanghai China Hartebeesthoek Radio Astronomy Observatory Krugersdorp South Africa Technical University of Munich Research Facility Satellite Geodesy Geodetic Observatory Wettzell Sackenrieder Str. 25 Bad Kötzting D-93444 Germany Guadalajara Yebes Spain Chalmers University of Technology Onsala Space Observatory Göteborg Sweden Aalto University Metsöhovi Radio Observatory Kylmälä Finland National Institute for Astrophysics RadioAstronomy Institute Radio Observatory Medicina Italy E-geos S.p.A Space Geodesy Center Italian Space Agency Matera Italy Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi China Yunnan Astronomical Observatory Chinese Academy of Sciences Kunming China School of Engineering Computer and Mathematical Sciences Faculty of Design and Creative Technologies Auckland University of Technology New Zealand Institute of Applied Astronomy of Russian Academy of Sciences St Petersburg Russia Korea Astronomy & Space Science Institute 776 Daedeok-daero Yuseong-gu Daejeon Korea Republic of

The radio signal transmitted by the Mars Express (MEX) spacecraft was observed regularly between the years 2013-2020 at X-band (8.42 GHz) using the European Very Long Baseline Interferometry (EVN) network and university of Tasmania’s telescopes. We present a method to describe the solar wind parameters by quantifying the effects of plasma on our radio signal. In doing so, we identify all the uncompensated effects on the radio signal and see which coronal processes drive them. From a technical standpoint, quantifying the effect of the plasma on the radio signal helps phase referencing for precision spacecraft tracking. The phase fluctuation of the signal was determined for Mars’ orbit for solar elongation angles from 0 - 180 deg. The calculated phase residuals allow determination of the phase power spectrum. The total electron content (TEC) of the solar plasma along the line of sight is calculated by removing effects from mechanical and ionospheric noises. The spectral index was determined as –2.43 ± 0.11 which is in agreement with Kolomogorov’s turbulence. The theoretical models are consistent with observations at lower solar elongations however at higher solar elongation (>160 deg) we see the observed values to be higher. This can be caused when the uplink and downlink signals are positively correlated as a result of passing through identical plasma sheets. © 2023, CC BY.

关键词： Solar wind