Measurement techniques enhancements for MIMO 4G mobile communication systems. extension of mode stirred reverberation chambers (MSRCs) emulation capabilities

[ENG] Mobile communications have experienced a brutal raise over the past 15 years. What started as a voice communication system (GSM or 2G) has finished yet as a data communication system of any kind, which in some cases has come to replace the conventional cabled data access infrastructure. This change in the use given to mobile devices necessarily entails a change in the underlying technology, which should be capable to provide the transmission speeds that these new applications require. This has emerged in recent years an increasing interest in multiple antenna techniques, usually referred as multiple-input multiple-output (MIMO) techniques, as they increase the spectral efficiency (and thus the transmission rate for a given bandwidth) of wireless systems. In this thesis, some of the factors limiting the ideal advantages of these multiantenna techniques are studied, in order to quantify the differences between the ideal behavior of 4G devices and behavior that users will experience in actual use conditions. The effect that the user has on the final performance of the devices is one of the main limitations that these devices are in daily use. Mobile phones are used almost all the time in the vicinity of the user, causing a decrease in the richness of the multipath electromagnetic environment (and thus a reduction of the MIMO benefits). As a result of this reduction, the number of signal paths that reach the user is also reduced. In this thesis both factors (user influence and influence of the number of signal paths) will be studied both for passive devices (antenna prototypes) and active devices (commercial phones). The second part of this thesis consist on the study of how to transfer some of these factors reducing the isotropicity of the environment, to one of the most promising measurement techniques, as it is the mode-stirred reverberation chamber (MSRC). This technique emulates naturally an isotropic rich multipath environment with the signal strength following a Rayleigh distribution. However, in this thesis two new techniques are proposed that allow the emulation of less isotropic environments without altering the basic operating principle of the MSRC. [SPA] Las comunicaciones móviles han experimentado un aumento brutal en los últimos 15 años. Lo que comenzó como un sistema de comunicación de voz (GSM o 2G) ha terminado todavía como un sistema de comunicación de datos de cualquier tipo, que en algunos casos ha llegado a sustituir la infraestructura de cableado convencional de acceso a datos. Este cambio en el uso que se da a los dispositivos móviles implica necesariamente un cambio en la tecnología subyacente, que debe ser capaz de proporcionar las velocidades de transmisión que estas nuevas aplicaciones requieren. Esto se ha convertido en los últimos años un creciente interés en las técnicas de múltiples antenas, normalmente se conoce como técnicas de múltiple entrada y múltiple salida (MIMO), ya que aumentan la eficiencia espectral (y por lo tanto la velocidad de transmisión para un ancho de banda dado) de los sistemas inalámbricos. En esta tesis, algunos de los factores que limitan las ventajas ideales de estas técnicas de múltiples antenas son estudiados, con el fin de cuantificar las diferencias entre el comportamiento ideal de dispositivos 4G y comportamiento que los usuarios experimentarán en condiciones reales de uso. El efecto que el usuario tiene sobre el rendimiento final de los dispositivos es una de las principales limitaciones que estos dispositivos son de uso diario. Los teléfonos móviles se utilizan en casi todo el tiempo en la proximidad del usuario, causando una disminución en la riqueza del entorno electromagnético trayectos múltiples (y por tanto una reducción de los beneficios MIMO). Como resultado de esta reducción, el número de trayectorias de señal que llegan al usuario también se reduce. En esta tesis ambos factores (la influencia del usuario y la influencia del número de caminos de señal) se estudió tanto para dispositivos pasivos (prototipos de antenas) y los dispositivos activos (los teléfonos comerciales). La segunda parte de esta tesis consisten en el estudio de cómo transferir algunos de estos factores que reducen la isotropicity del medio ambiente, a una de las técnicas de medición más prometedores, como es la cámara de agitación de modos (MSRC). Esta técnica emula naturalmente un entorno isotrópico multipath rico con la intensidad de la señal después de una distribución de Rayleigh. Sin embargo, en esta tesis, dos nuevas técnicas que se proponen permitir la emulación de entornos isotrópicos menos sin alterar el principio de funcionamiento básico del MSRC.Universidad Politécnica de Cartagen

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

Mode-stirred chamber sample selection technique applied to antenna correlation coefficient

Mode-stirred chambers provide an excellent tool for antenna characterization. Recent research has focused on making the mode-stirred chamber technique more versatile. One result of these efforts is the sample selection technique, by which a subset of data with specific properties is extracted from a measured set of raw data. This paper presents how to apply the sample selection technique to measurements of the correlation coefficient in dual antenna measurements, for example, for diversity or MIMO applications. Theoretical background and useful mathematical relations are presented. The application is verified through measurements.This work was supported in part by the Spanish National R & D Programme through TEC 2008-05811 and by Fundacion´ Seneca, the R & D coordinating agency for the Region of ´ Murcia (Spain) under the 11783/PI/09 and 11610/IV2/09 Projects

Emulation of MIMO rician-fading environments with mode-stirred reverberation chambers

Some recent publications have extended the emulating capabilities of mode-stirred reverberation chambers, which are now able to emulate Ricean-fading and non-isotropic environments. Either the need to physically modify existing chambers or multiple sets of measurements is required for these enhancements. In this paper a novel post-processing hybrid tool is presented for the transformation of a Rayleigh-fading emulated environment into a Rician one. The model is tested and compared to outdoor measurements and simulations through the K-factor, correlation, diversity gain and MIMO capacity. Results show an excellent matching performance with no hardware modifications of mode-stirred chambers with just one set of measurements. The method is patent prot cted by EMITE Ing.This work was supported in part by Fundación Séneca, the R&D unit of the Autonomous Region of Murcia (Spain) under project reference 11783/PI/09 and in part by the Spanish National R&D Programme through TEC2008-05811. J. Valenzuela-Valdés is with the EMITE Ingeniería SLNE, Edificio CEEIM, E-30100 Espinardo, Murcia, Spain (e-mail: [email protected]). J. D. Sánchez-Heredia, A. M. Martínez-González, and D. A. Sánchez-Hernández are with the Departamento de Tecnologías de la Información y Comunicaciones, Universidad Politécnica de Cartagena, Cartagena E-30202, Spain (e-mail: [email protected])

Limit for the proportion of remaining samples in the modestirred chamber sample selection technique

An expression is derived for the maximum proportion of remaining samples in the sample selection technique for mode-stirred chamber measurements. The limit is independent of the selection algorithm used. The limit is verified in simulations as well as measurement examples.This work was supported in part by the Spanish National R&D Programme through TEC2008-05811, and by Fundacio´n Se´neca, the R&D coordinating agency for the Region of Murcia (Spain) under the 11783/PI/09 and 11610/IV2/09 project

Advances in mode-stirred reverberation chambers for wireless communication performance evaluation

Reverberation chambers (RC) are a popular tool for laboratory wireless communication performance evaluation, and their sandardization for Over-The-Air (OTA) measurements is underway. Yet, the inherent limitations of singlecavity RCs to emulate isotropic Rayleigh-fading scenarios with uniform phase distribution and high elevation angular spread put their representation of realistic scenarios into jeopardy. Recent advances in the last few years, however, have solved all these limitations by using more general mode-stirred reverberation chambers (MSC), wherein the number of cavities, their stirring and coupling mechanisms, and their software postprocessing algorithms is far from simple, representing a new era for wireless communications research, development, and over-the-air testing. This article highlights recent advances in the development of second-generation mode-stirred chambers for wireless communications performance evaluatio

Multipath simulator measurements of handset dual antenna performance with limited number of signal paths

Antenna pairs for diversity or MIMO functionality are characterized under the assumption of a certain statistical distribution of the incident signals over angle and polarization, but also assuming a signal environment with a large number of signal paths. In many real-life environments, however, only a few signal paths contain most of the transferred power. A multipath simulator can be used to realize signal environments with a controlled number of signal paths. This paper presents measurements of dual antenna performance using amultipath simulator with 2–16 signal paths. The results are analyzed in terms of statistical power distributions,power imbalance, correlation coefficient, multiplexing efficiency, and diversity gain. Differences in performance depending on the number of signal paths are noted, illustrating the value of considering the number of signal paths in characterization.The work was supported in part by MICINN (Project TEC2008-05811) through an FPI doctoral grant (BES-2009-013764

MIMO TIS/TRP active testing with second-generation mode-stirred chambers

With the first 4G trials scheduled for 2010 and the compulsory use of MIMO into both WiMAX and LTE standards, MIMO technology has finally exploded. Mobile Internet Peripherals and Devices are said to take a market share of 30% of all handsets and non-handsets wireless devices by 2013. In this complex scenario, antenna engineering has gained a tremendous importance. While the use of multiple antennas in the base station or access point (AP) is usually feasible, user terminals have size and weight restrictions that make the use of conventional antenna elements such as dipoles or patch antennas problematic. Thus, novel array topologies and antenna elements for multi-antenna systems are of great interest. But not only new geometries and designs are required, but also the antenna engineer is faced with a novel way to evaluate performance. While the parameters to characterize antennas in general are well defined and worldwide accepted, the way to evaluate the performance of an antenna array for MIMO is still an open issue, since multiple new concepts have to be considered, such as pattern diversity, corrrelation among elements, fading environment or polarization diversity, among others. Typical active parameters being currently tested for 2G and 3G systems are Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS). 4G systems are already envisioned to require more complex active testing due their inherently embedded MIMO technology. In this article, the way of using a second generation mode-stirred chamber (EMITE Ing E300 MIMO Analyzer) connected to a rradiocommunications tester (Rohde & Schwarz CMU200) to characterize wireless devices by measuring TRP and TIS is decribed. Measurements have been perormed for the UMTS system, but are simply extende to other systems. Since second-generation mode-stirred chambers can emulate a wide variety of Rayleigh, Rician, isotropic and non-isotropic scenarios, the procedure described in this paper opens the door for more advanced evaluation of active parameters for a variety of fading scenarios, which is unheard of in the wireless communications arena.Ministerio de Educación y Cienci

Sample selection algorithms for enhanced MIMO antenna measurements using mode-stirred reverberation chambers

Mode-stirred reverberation chambers (MSRCs) are a useful tool for measuring several wireless-related MIMO antenna parameters. In a conventional single-cavity MSRC, the emulated fading environment is isotropic and the amplitude of the signal is Rayleigh distributed. Previous contributions have enhanced the emulation capabilities ofMSRCs so as to include the ability to emulate Rician- and non-isotropic fading environments. In this contribution, arbitrary amplitude probability density functions (PDF) emulation using a MSRC is presented by selecting parts of the sample set that forms different statistical ensembles. Several algorithms are presented and compared in terms of computation time and power accuracy using simulated as well as measured data from different MSRCs to obtain Rician, on-body and amplitude PDFs of standardized models. The technique is patent-protected by EMITEThis work was supported in part by the Spanish National R&D Programme through TEC2008-0581

A new stream treefrog of the genus Hyloscirtus (Amphibia, Hylidae) from the Río Negro-Sopladora National Park, Ecuador

Recent surveys in the Río Negro-Sopladora National Park revealed a striking new species of Hyloscirtus. The new species is easily diagnosed from all other congeners by its large body size (64.9 mm SVL in adult female); broad dermal fringes in fingers and toes; prepollex not projected into a prepollical spine and hidden under thenar tubercle; dorsum greyish-green, with paler-hued reticulum, yellow spots and black speckles; throat, venter, flanks and hidden surfaces of limbs golden-yellow with large black blotches and spots; fingers, toes and webbing yellow with black bars and spots; iris pale pink with black periphery. It is currently known only from its type locality, in the high montane forest on the southern slopes of the Cordillera Oriental of the Andes, southeastern Ecuador. The new species might be related to the H. larinopygion species group based on its morphology