Combination of the three types of diversity to design high capacity compact MIMO terminal

Multiple-input-multiple-output (MIMO) schemes designed to increase channel capacity face strong limitations when a large number of antennas must be deployed in a terminal due to size constrains. This letter discusses how the different combinations of the three types of diversities-namely spatial, radiation pattern, and polarization diversity-can be used to get an improved capacity in compact terminals. The study compares realistic combinations that overcome the need for a large number of radiating elements in the user terminal.This work was supported in part by the Spanish Ministry of Sci-ence and Innovation under Project GRE3NSYST (TEC2011-29006-C03-03), Project TEC2013-44019-R, and the CONSOLIDER-INGENIO 2010 program under Project COMONSENS (CSD 2008-00010).Publicad

Design and Analysis of Conformal Antenna for Future Public Safety Communications: Enabling Future Public Safety Communication Infrastructure

Future 4G wireless communication systems include, in their capabilities portfolio, emergency-specific needs, such as data support, broadband communication, and extremely high reliability. An emergency situation can be addressed with undoubtedly more chances of success if augmented information is enabled within the public safety communication novel capabilities. In this article, for a fully augmented information provision based on broadband transmission, a user-end (UE) communication-capabilities enhancement is addressed by deploying multiple antennas without compromising the portability and light weight of first-responder equipment. With this aim, we propose the design of a 4.9-GHz conformal antenna array at the rescuer side (integrated in a helmet) and evaluate its performance in terms of relative data rate gain. The conformal array design is based on traditional patch antennas that consider the need for deployment over an ellipsoidal surface. The antenna array is simulated and then built, and several parameter characterizations (bandwidth, radiation pattern, reflection coefficient, and MC) and measurements are undertaken to ensure the suitability of the design. Furthermore, an analysis of the specific absorption rate (SAR) is performed to guarantee that the exposure to electromagnetic fields is below the standardized levels.The authors would like to thank Prof. Eva Rajo-Iglesias from Universidad Carlos III de Madrid. This work has been partly funded by the Spanish Government through projects CIES (RTC-2015-4213-7), MIMOTEX (TEC2014-61776-EXP) and TERESAADA (TEC2017-90093-C3-2-R) (MINECO/AEI/FEDER, UE

Design and Evaluation of Compact Multi-antennas for Efficient MIMO Communications

The use of multi-antenna systems with multiple-input multiple-output (MIMO) technology will play a key role in providing high spectrum efficiency for next generation mobile communication systems. This thesis offers valuable insights on the design of compact multi-antennas for efficient MIMO communications. In the course of the thesis work, several novel six-port antenna designs have been proposed to simultaneously exploit all six possible degrees-of-freedom (DOFs) by means of various antenna diversity mechanisms (Paper I & II). Moreover, the thesis also examines the potential of using uncoupled matching networks to adaptively optimize compact multi-antenna systems to their dynamic usage environments (Paper III). Furthermore, a simple and intuitive metric is proposed for evaluating the performance of MIMO antennas when operating in the spatial multiplexing mode (Paper IV). Last but not least, cooperation among multi-antenna systems at all three sectors of a given cellular base station is shown to deliver significant benefit at sector edges (Paper V). The thesis with five included research papers extend the understanding of MIMO systems from an antenna and propagation perspective. It provides important guidelines in designing compact and efficient MIMO antennas in their usage environments. In Paper I, a fundamental question on the number of effective DOFs in a wireless channel is explored using two co-located six-port antenna arrays. The antenna elements of both arrays closely reproduce the desired characteristics of fundamental electric and magnetic dipoles, which can efficiently extract angle and polarization diversities from the wireless channel. In particular, one of the two array designs is by far the most electrically compact six-port antenna structure in the literature. Analysis of measured channel eigenvalues in a rich multi-path scattering environment shows that six eigenchannels are successfully attained for the purpose of spatial multiplexing. To study the potential of implementing different diversity mechanisms on a practical multi-port antenna, Paper II builds on an existing dielectric resonator antenna (DRA) to provide a compact six-port DRA array that jointly utilizes space, polarization and angle diversities. In order to fully substantiate the practicality of the DRA array for indoor MIMO applications, the compact DRA array together with two reference but much larger arrays were evaluated in an office scenario. The use of the compact DRA array at the receiver is shown to achieve comparable performance to that of the reference monopole array due to the DRA array's rich diversity characteristics. In Paper III, the study of uncoupled matching networks to counteract mutual coupling effects in multi-antenna systems is extended by allowing for unbalanced matching impedances. Numerical studies suggest that the unbalanced matching is especially effective for array topologies whose effective apertures can vary significantly with respect to the propagation channel. Moreover, it is also demonstrated that the unbalanced matching is capable of adapting the radiation patterns of the array elements to the dynamic propagation environment. Paper IV introduces multiplexing efficiency as a performance metric which defines the loss of efficiency in decibel when using a multi-antenna prototype under test to achieve the same multiplexing performance as that of an ideal array in the same propagation environment. Its unique features are both its simplicity and the valuable insights it offers with respect to the performance impacts of different antenna impairments in multi-antenna systems. In Paper V, intrasite cooperation among three 120°-sector, each with a cross-polarized antenna pair, is investigated in a measured urban macrocellular environment. The single-user capacity improvement is found to exceed 40% at the sector edges, where improvements are most needed. In addition, a simple simulation model is developed to analyze the respective impact of antennas and specific propagation mechanisms on the measured cooperative gain

A Comprehensive Survey on 'Various Decoupling Mechanisms with Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems'

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the arrays characteristics such as bandwidth, gain and radiation efficiency, and physical footprint

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array’s characteristics such as bandwidth, gain and radiation efficiency, and physical footprint

Diseño de un sistema de comunicaciones MIMO masivo multiusuario

Hoy en día, las tecnologías inalámbricas tienen gran importancia en la sociedad. Es por esto por lo que se busca la manera de mejorar los servicios que aportan y de aumentar el número de usuarios permitidos para estas comunicaciones. El principal objetivo del presente documento es conocer cómo mejora la tecnología MU-MIMO (Multi-User Multiple-Input Multiple-Output) con el incremento del número de usuarios que pertenecen al sistema. Para ello en primer lugar se realizará un estudio de la evolución de la tecnología MU-MIMO. Primero se analizará cómo se consiguió llegar al origen de MIMO o SU- MIMO (Single-User Multiple-Input Multiple-Output), mediante las tecnologías SISO (Single-Input Single-Output), MISO (Multiple-Input Single-Output) y SIMO (Single- Input Multiple-Output). Posteriormente se realizará un estudio de cómo se comporta un sistema SU-MIMO y en qué se diferencia de MU-MIMO. También se tratará como MU-MIMO mejora la tecnología MIMO y las categorías en las que se divide y se realizará un estudio matemático del canal MIMO que se va a utilizar en las simulaciones. Por último, se realizarán unas simulaciones. Estas simulaciones se realizarán con un escenario definido por un número variable de usuarios que transmiten a una estación base, que adquiere el papel del receptor. En este escenario, los usuarios tienen 10 antenas colocadas en vertical mientras que la estación base recibe con un array de 100 antenas. En estas simulaciones se analizarán principalmente dos características en el enlace ascendente: la dispersión angular del receptor y la capacidad del canal. El objetivo de las simulaciones es observar como la dispersión angular adquiere una distribución uniforme según va aumentando el número de usuarios, frente a la distribución Gaussiana que tiene con un número bajo de usuarios. Y por otra parte, observar como este hecho permite que la capacidad del sistema mejore.Nowadays, wireless communication has a great importance in the society, for this reason it’s necessary to look for a new technology that improves the service as well as the maximum number of users allowed in this type of communication. The main objective of this project is to get to know the behaviour of MU-MIMO technology (Multi-User Multiple-Input Multiple-Output) when the number of users in the system is increasing. Firstly, there will be shown a study according to the evolution of MU-MIMO, presenting the necessities that boosted the technology MIMO and furthermore the sub-technologies of MIMO: SU-MIMO (Single-User Multiple-Input Multiple-Output), SISO (Single-Input Single-Output), MISO (Multiple-Input Single-Output) and SIMO (Single-Input Multiple-Output). Secondly, a study related to how SU-MIMO works will be presented. Moreover there will be displayed the differences between SU-MIMO and MU-MIMO and how MU-MIMO improves the efficiency of the system. In addition, a mathematical demonstration of MIMO channel will be studied as well as MIMO subcategories. Finally, it will be shown different simulations. These simulations are based on an uplink communication in which the number of users transmitting is variable. The total number of vertical antennas per user is 10 meanwhile the base station has 100 antennas receiving. The aim of these simulations is to get familiar to the performance of MU-MIMO according to two main variables: the angular dispersion of the receiver and capacity channel. The main objective of these simulations is to observe how the angular dispersion of the receiver changes from a Gaussian distribution to a uniform distribution when the number of users increases. Also, it is shown how the capacity changes according to the number of users in the system.Ingeniería en Tecnologías de Telecomunicacione