Addressing the 5G cell switch-off problem with a multi-objective cellular genetic algorithm

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The power consumption foreseen for 5G networks is expected to be substantially greater than that of 4G systems, mainly because of the ultra-dense deployments required to meet the upcoming traffic demands. This paper deals with a multi- objective formulation of the Cell Switch-Off (CSO) problem, a well-known and effective approach to save energy in such dense scenarios, which is addressed with an accurate, yet rather unknown multi-objective metaheuristic called MOCell (multi- objective cellular genetic algorithm). It has been evaluated over a different set of networks of increasing densification levels. The results have shown that MOCell is able to reach major energy savings when compared to a widely used multi-objective algorithm.TIN2016-75097-P Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

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

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.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Optimization of massive connections in 5G networks for IoT

The expected traffic demands for the coming years requires a major technology development. Indeed, from 2017 to 2022, the global annual traffic growth is estimated to reach 220%. This annual growth leads in turn to an increase in the number of users connected to IP networks, going from 2.4 to 3.6 devices connected per person. Currently, 4G networks are capable of handling this load, but the irruption of the 5G breakthroughs, expected to be at full operation by 2020, is visible. However, 5G technologies may come along with a considerable power consumption if they are not devised properly. As a consequence, a key issue in the developing of these networks is to make them energetically sustainable. In this work, a preliminary study of the optimization of various aspects of the 5G system is presented. It addresses the configuration of the different basic parameters of the system and optimizes the power transmitted by the base stations to obtain simultaneous improvements in system capacity and its power consumption for a massive connections scenario. To the best of our knowledge, this is the very first time this type of 5G scenario is optimized with these two performance criteria.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Emulation of MIMO nonisotropic fading environments with reverberation chambers

Some recent publications have extended the emulating capabilities of reverberation chambers. While polarization imbalance has been removed and Ricean-fading environments are now properly emulated, these chambers are still limited to isotropic nonline of sight (NLOS) scattering. By controlling the power received, number of resolvable multipath components (MPC), angular spread (AS), and angle of arrival (AoA), the emulation of real-propagating environments with both isotropic and nonisotropic scattering are demonstrated in this letter using a reverberation chamber with several multiple-input–multiple-output (MIMO) arrays.This work was supported in part by the Fundación Séneca, the R&D unit of the Autonomous Region of Murcia (Spain) under project references TIC-TEC 07/02-0005 and by the Spanish National R&D Programme through TEC2007/63470/TCM

Effect of user presence on receive diversity and MIMO capacity for rayleigh-fading channels

The effects of the presence of the user on multipleinput– multiple-output (MIMO) performance for wireless communications systems is investigated through measurements in a reverberation chamber. Measured results have demonstrated that despite a decrement on the envelope correlation coefficient, a degradation of both diversity gain and MIMO capacity are expected when the user is present. While the validity of the correlation coefficients for predicting MIMO performance is limited in the presence of the user, the effects have also been found to be strongly dependent upon frequency, antenna topology, and user characteristics.This work was supported in part by the Fundación Séneca, the R&D coordinating unit of the Autonomous Region of Murcia (Spain) under Projects 2I05SU0033 and TIC-TEC 06/01-0003

Sample selection method for arbitrary fading emulation using mode-stirred chambers

Mode-stirred chambers (MSC) consist on one or more resonant cavities coupled in some way in order to allow the measurement of different antenna parameters such as antenna efficiency, correlation, diversity gain or MIMO capacity, among others. In a single-cavity mode-stirred chamber, also known as a reverberation chamber (RC), the environment is isotropic and the amplitude of the signal is Rayleigh distributed. Real environments, however, rarely follow an isotropic Rayleigh-fading scenario. Previous results have shown that a Rician-fading emulation can be obtained via hardware modification using an RC. The different methods lack from an accurate emulation performance and are strongly dependent upon chamber size and antenna configurations. With the innate complexity of more-than-one cavity MSC, the coupling structure generates sample sets which are complex enough so as to contain different clusters with diverse fading characteristics. This paper presents a novel method to accurately emulate a more realistic Rician-fading distribution from a Rayleigh-fading distribution by selecting parts of the sample set that forms different statistical ensembles using a complex two-cavity multi-iris-coupled MSC. Sample selection is performed using a genetic algorithm. Results demonstrate the potential of MSCs for versatile MIMO fading emulation and OTA testing. The method is patent protected by EMITE Ing.This work was supported in part by the Spanish National R&D Programme through TEC2008-05811 and by Fundación Séneca, the R&D coordinating agency for the Region of Murcia (Spain) under the 11783/PI/09 project

Accurate Estimation of Correlation and Capacity for Hybrid Spatial-Angular MIMO Systems

In this paper, several novel functions for accurately estimating the correlation and the multiple-input–multiple-output (MIMO) capacity of combined spatial and true polarization diversity (TPD) schemes are proposed for the first time. Minimum error estimation of the correlation for a hybrid spatial–TPD linear scheme previously reported cannot be obtained by simple nonlinear least-square estimators, and the use of genetic algorithms (GAs) provides an accurate solution. Channel matrix coefficients and MIMO capacities are analyzed for the diverse optimization strategies employed, which aim to identify the best prediction of MIMO performance. The novel functions are used with previously reported results and validated for Rayleigh fading scenarios with isotropic scattering using a multimode-stirred chamber (MIMO Analyzer). An accurate prediction of high correlation values is concluded to be of extreme importance for the final MIMO performance estimation. This has been found to be particularly important for estimating MIMO capacity with achieved prediction accuracies of 1.1% at SNR = 15 dB. In contrast, the accurate prediction of low correlation values has been found to have a less-important effect on the final capacity-predicting performance.This work was supported in part by the Spanish National R&D Program under Grant TEC2008-05811

Optimized Varactor Parasitic Modelling in the Millimeter-Wave Band.

This work explores the utilization of varactors in the millimeter-wave (mm-wave) band, specifically focusing on their application in voltage-controlled reconfigurable devices. Varactors, or variable capacitors, can adjust capacitance through voltage control, making them ideal for creating rapidly variable systems for radiofrequency (RF) applications. However, parasitic elements in varactors can significantly affect their performance when moving up to the millimeter-wave band and limit their efficiency. Therefore, this work aims to present an optimization approach that accurately calculates the parasitic model for these varactors.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Redes de sensores seguras y eficientes con beamforming

Mejorar la eficiencia energética de las redes de sensores (WSN, por sus siglas en inglés) es uno de sus principales objetivos de diseño. De entre las distintas líneas de trabajo existentes en esta área, el uso del conformado del haz, o beamforming, está en auge en la actualidad, ya que proporciona una forma de transmitir señales de radio muy eficiente hacia un conjunto dado de direcciones destino. En este trabajo, el beamforming se ha utilizado para incrementar, por una parte, el tiempo de vida de las WSNs y, por otro, el nivel de seguridad de la red, evitando establecer comunicaciones en direcciones donde se conoce la existencia de nodos enemigos. El problema se ha formulado agregando dichos objetivos en una única función de fitness, y cuyas soluciones tentativas están compuestas por las amplitudes y fases de las antenas instaladas en los nodos de la WSN. Sobre distintos escenarios sintéticos, los resultados han mostrado que es posible reducir el consumo energético de una WSN y, a la vez, proporcionar comunicaciones seguras ante la presencia de posibles atacantes.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Plan Nacional de Investigación del Ministerio de Economía y Competitividad bajo el proyecto TIN2016-75097-P

Human Head Natural Protection Against Electromagnetic Fields

In this paper we provide concluding evidence that the human skull acts as a dynamic barrier to electromagnetic fields (EMF) and temperature flow at 1800 MHz. This natural helmet e®ectively and dynamically protects brain tissue against safety-de¯ned threshold temperature increase due to external EMF induction. A half-wavelength dipole antenna has been employed as the EMF source. The human head is modelled by several coronal planes extracted from the Visible Human Project. Results described here have a great importance should thermal e®ects be directly used to derive basic restrictions to EM fields safety limits for human exposure.FUNDACIÓN SENECA. Plan de Ciencia y Tecnología de la Región de Murcia. Código: 05746/PI/07