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3rd International Conference on Optimization and Learning (OLA)

作者： Luna, Francisco Zapata-Cano, Pablo H. Palomares-Caballero, Angel Valenzuela-Valdes, Juan F. Univ Malaga Dept Comp Sci & Programming Languages Malaga 29071 Spain Univ Granada Dept Signal Theory Telemat & Commun CITIC Granada 18071 Spain

ISBN: (纸本)9783030419134;9783030419127

Network densification with deployments of many small base stations (SBSs) is a key enabler technology for the fifth generation (5G) cellular networks, and it is also clearly in conflict with one of the target design requirements of 5G systems: a 90% reduction of the power consumption. In order to address this issue, switching off a number of SBSs in periods of low traffic demand has been standardized as an recognized strategy to save energy. But this poses a challenging NP-complete optimization problem to the system designers, which do also have to provide the users with maxima capacity. This is a multi-objective optimization problem that has been tackled with multi-objective evolutionary algorithms (MOEAs). In particular, a problem-specific search operator with problem-domain information has been devised so as to engineer hybrid MOEAs. It is based on promoting solutions that activate SBSs which may serve users with higher data rates, while also deactivating those not serving any user at all. That is, it tries to improve the two problem objectives simultaneously. The resulting hybrid algorithms have shown to reach better approximations to the Pareto fronts than the canonical algorithms over a set of nine scenarios with increasing diversity in SBSs and users.

关键词： Problem specific operator Hybridization Multi-objective optimization Cell switch-off problem 5G networks

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Evaluation of Quantum Annealer Performance via the Massive MIMO Problem

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IEEE ACCESS 2021年 9卷 131658-131671页

作者： Tabi, Zsolt, I Marosits, Adam Kallus, Zsofia Vaderna, Peter Godor, Istvan Zimboras, Zoltan Ericsson Res H-1117 Budapest Hungary Eotvos Lorand Univ Dept Programming Languages & Compilers H-1117 Budapest Hungary Budapest Univ Technol & Econ Dept Broadband Infocommun & Electromagnet Theory H-1111 Budapest Hungary Budapest Univ Technol & Econ Dept Anal H-1111 Budapest Hungary Wigner Res Ctr Phys Quantum Comp & Informat Grp H-1121 Budapest Hungary

Quantum annealing offers an appealing route to handle large-scale optimization problems. Existing Quantum Annealing processing units are readily available via cloud platform access for solving Quadratic Unconstrained Binary Optimization (QUBO) problems. In particular, the novel D-Wave Advantage device has been recently released. Its performance is expected to improve upon the previous state-of-the-art D-Wave 2000Q annealer, due to higher number of qubits and the Pegasus topology. Here, we present a comparative study via an ensemble of Maximum Likelihood (ML) Channel Decoder problems for MIMO scenarios in Centralized Radio Access Network (C-RAN) architectures. The main challenge for exact optimization of ML decoders with ever-increasing demand for higher data rates is the exponential increase of the solution space with problem sizes. Since current 5G solutions mainly use approximate methodologies, Kim et al. leveraged Quantum Annealing for large MIMO problems with Phase Shift Keying and Quadrature Amplitude Modulation scenarios. Here, we extend their work and analyze experiments for more complex modulations and larger MIMO antenna array sizes. By implementing the extended QUBO formulae on the novel annealer architecture, we uncover the limits of state-of-the-art quantum optimization for the massive MIMO ML decoder. We report on the improvements and discuss the uncovered limiting factors learned from the 64-QAM extension. We include the enhanced evaluation of raw annealer sampling via implementation of post-processing methods in the comparative analysis between D-Wave 2000Q and the D-Wave Advantage system.

关键词： Annealing Antenna arrays Optimization Maximum likelihood decoding Qubit Modulation Massive MIMO Channel decoding graph embedding massive MIMO NP-hard optimization quantum annealing quantum computing telecommunication

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Phase Shifter for Millimeter-Wave Frequency Range Based on Glide Symmetric Structures 13

Phase Shifter for Millimeter-Wave Frequency Range Based on G...

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13th European Conference on Antennas and Propagation (EuCAP)

作者： Palomares-Caballero, Angel Alex-Amor, Antonio Valenzuela-Valdes, Juan Luna, Francisco Padilla, Pablo Univ Malaga Dept Comp Sci & Programming Languages Malaga Spain Univ Granada CITIC Dept Signal Theory Telemat & Commun Granada Spain

ISBN: (纸本)9788890701887

The use of glide symmetry in radiofrequency devices to introduce dispersive effects has been recently proposed and demonstrated. One of these effects is to control the propagation constant of the structure. Here, we propose a mm-wave phase shifter whose elements have a glide-symmetric configuration to achieve a greater phase shift in the same waveguide space than the non-glide-symmetric case. The glide-symmetric phase shifter is implemented in waveguide technology and is formed by rows of metallic pins that produce the desired phase shift. To assess the better performance of the glide-symmetric phase shifter, it is compared to its non-glide-symmetric version whose metallic pins are located only in one of the broad sides of the waveguide. The operating frequency range of the phase shifter is 67 to 75 GHz. Results show a 180 degree phase shift in regard to the reference waveguide without pins, and 50 degrees more than the non-glide-symmetric version.

关键词： phase shifter glide symmetry mm-waves waveguide

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Helix antenna array based on higher symmetries for antenna miniaturization and mutual coupling reduction 9

Helix antenna array based on higher symmetries for antenna m...

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IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC)

作者： Palomares-Caballero, Angel Alex-Amor, Antonio Fco Valenzuela-Valdes, Juan Padilla, Pablo Univ Malaga Dept Comp Sci & Programming Languages Malaga 29071 Spain Univ Granada Dept Signal Theory Telemat & Commun CITIC Granada 18071 Spain

ISBN: (纸本)9781728105666

This document presents the design of an array of helix antennas in axial mode based on higher symmetries. These higher symmetries permit, for a given frequency, the miniaturization of the antenna. Therefore, an array formed by this kind of miniaturized antennas presents lower mutual coupling among the constituting antennas. A comparison is made between the performance of antenna arrays formed by conventional and glide-and-twist-symmetrical helix antennas. The results show a decrease in mutual coupling in the glide-and-twist- symmetrical helix array, regarding to the conventional helix array, for the same element spacing. Moreover, better radiation performance is achieved in terms of directivity and gain in the miniaturized helix array.

关键词： helix antennas higher symmetries array miniaturization mutual coupling reduction

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Polynomial speedup in Torontonian calculation by a scalable recursive algorithm

arXiv

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arXiv 2021年

作者： Kaposi, Ágoston Kolarovszki, Zoltán Kozsik, Tamás Zimborás, Zoltán Rakyta, Péter Department of Programming Languages and Compilers Eötvös Loránd University Budapest Hungary Wigner Research Centre for Physics The Hungarian Academy of Sciences Budapest Hungary BME-MTA Lendület Quantum Information Theory Research Group Budapest Hungary Department of Physics of Complex Systems Eötvös Loránd University Budapest Hungary

Evaluating the Torontonian function is a central computational challenge in the simulation of Gaussian Boson Sampling (GBS) with threshold detection. In this work, we propose a recursive algorithm providing a polynomial speedup in the exact calculation of the Torontonian compared to state-of-the-art algorithms. According to our numerical analysis the complexity of the algorithm is proportional to N1.06912N/2 with N being the size of the problem. We also show that the recursive algorithm can be scaled up to HPC use cases making feasible the simulation of threshold GBS up to 35 − 40 photon clicks without the needs of large-scale computational capacities. © 2021, CC BY-SA.

关键词： Computational complexity

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Phase Shifter for Millimeter-Wave Frequency Range Based on Glide Symmetric Structures

Phase Shifter for Millimeter-Wave Frequency Range Based on G...

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European Conference on Antennas and Propagation

作者： Angel Palomares-Caballero Antonio Alex-Amor Juan Valenzuela-Valdes Francisco Luna Pablo Padilla Department of Computer Science and Programming Languages University of Malaga Malaga Spain Dept. of Signal Theory University of Granada-CITIC Granada Spain

关键词： Phase shifters Pins Europe Millimeter wave technology Array signal processing Dispersion

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On the Ultra-Dense Small Cell Deployment for 5G Networks 1

On the Ultra-Dense Small Cell Deployment for 5G Networks

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1st IEEE 5G World Forum, 5GWF 2018

作者： Valenzuela-Valdés, Juan Fco Palomares, Ángel González-Macías, Juan C. Valenzuela-Valdés, Antonio Padilla, Pablo Luna-Valero, F. Department of Signal Theory Telematics and Communications - CITIC University of Granada Granada18071 Spain Department of Computer Science and Programming Languages University of Malaga Malaga29071 Spain

ISBN: (纸本)9781538649824

The paradigm shift that has to take place in the new 5G networks in order to meet the expected data rates is a huge technological challenge. The use of super dense heterogeneous networks is one of the most promising alternatives to provide services with speeds above 1 Gbps. Another option to increase bandwidth is to engineer base stations at higher working frequencies and, thus higher available bandwidth, but also having the issues of the component cost and the increased propagation losses. This work evaluates the deployment of ultradense networks with base stations at different frequencies, ranging from 2 GHz to 60 GHz. Different scenarios that use several densities of both base stations and user equipments have been analyzed. The network performance has been measured in terms of Capacity, Signal to Interference plus Noise Ratio, and Energy Consumption. © 2018 IEEE.

关键词： 5G mobile communication systems

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Electromagnetic Near-Field Inhomogeneity Reduction for Image Acquisition Optimization in High-Resolution Multi-Channel Magnetic Resonance Imaging (MRI) Systems

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IEEE ACCESS 2017年 5卷 5149-5157页

作者： Padilla, Pablo Valenzuela-Valdes, Juan F. Padilla, Jose L. Luna-Valero, Francisco Univ Granada Dept Signal Theory Telemat & Commun E-18071 Granada Spain Ecole Polytech Fed Lausanne Nanoelect Devices Lab CH-1015 Lausanne Switzerland Univ Granada Dept Elect & Comp Technol E-18071 Granada Spain Univ Malaga Dept Comp Sci & Programming Languages E-29071 Malaga Spain

This paper is a study of the inhomogeneity reduction for near-field acquisition in high-resolution magnetic resonance imaging (MRI) systems. The acquisition homogeneity in MRI imaging modality is an open issue concerning the optimal MRI image generation in terms of the RF signal acquisition. The acquisition inhomogeneity is related to the radiation patterns of the receiving antennas and its location in the MRI system, among other relevant aspects. The acquisition inhomogeneity is translated into two main effects: pattern ripples at the outer cylindrical rings and radial inhomogeneity when comparing the center value ( maximum) with the rest of the pattern. To overcome these effects, two strategies are proposed. In the first one, it is proposed to progressively vary the antenna location in the azimuthal array distribution. In the second one, it is proposed to progressively vary the antenna amplitude and phase feeding in the array distribution. To compute a figure of merit of the pattern radial uniformity and the ripples, two metrics are defined in this paper. It is proved that both the progressive modification in the location at each array ring and the variation of the feeding phase of each array ring reduce the pattern ripples and radial inhomogeneity. Optimal values for either the angular rotation or the feeding phase values can be calculated, depending on the particular dimensions of the cylinder that conforms the region of interest.

关键词： Field homogeneity MRI systems near field

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Clustering and Beamforming for Efficient Communication in Wireless Sensor Networks

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SENSORS 2016年第8期16卷 1334-1334页

作者： Porcel-Rodriguez, Francisco Valenzuela-Valdes, Juan Padilla, Pablo Luna-Valero, Francisco Luque-Baena, Rafael Angel Lopez-Gordo, Miguel Univ Granada Dept Signal Theory Telemat & Commun CITIC E-18071 Granada Spain Univ Malaga Dept Comp Sci & Programming Languages E-29071 Malaga Spain Univ Extremadura Dept Comp & Telemat Syst Engn Merida 06800 Spain

Energy efficiency is a critical issue for wireless sensor networks (WSNs) as sensor nodes have limited power availability. In order to address this issue, this paper tries to maximize the power efficiency in WSNs by means of the evaluation of WSN node networks and their performance when both clustering and antenna beamforming techniques are applied. In this work, four different scenarios are defined, each one considering different numbers of sensors: 50, 20, 10, five, and two nodes per scenario, and each scenario is randomly generated thirty times in order to statistically validate the results. For each experiment, two different target directions for transmission are taken into consideration in the optimization process (phi = 0 degrees and theta = 45 degrees;phi = 45 degrees, and theta = 45 degrees). Each scenario is evaluated for two different types of antennas, an ideal isotropic antenna and a conventional dipole one. In this set of experiments two types of WSN are evaluated: in the first one, all of the sensors have the same amount of power for communications purposes;in the second one, each sensor has a different amount of power for its communications purposes. The analyzed cases in this document are focused on 2D surface and 3D space for the node location. To the authors' knowledge, this is the first time that beamforming and clustering are simultaneously applied to increase the network lifetime in WSNs.

关键词： wireless sensors networks energy efficiency beamforming optimization techniques

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Special Issue: Special section on BPM 2011 conference

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INFORMATION SYSTEMS 2013年第4期38卷 545-546页

作者： Weske, Mathias Rinderle-Ma, Stefanie Toumani, Farouk Wolf, Karsten Univ Potsdam Hasso Plattner Inst D-14482 Potsdam Germany Univ Wien Res Grp Workflow Syst & Technol A-1090 Vienna Austria Pascale Univ LIMOS UMR CNRS 6158 Paris France Univ Rostock Inst Comp Sci LS Theory Programming Languages & Programming D-18051 Rostock Germany

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