Millimeter-wave Evolution for 5G Cellular Networks

Triggered by the explosion of mobile traffic, 5G (5th Generation) cellular network requires evolution to increase the system rate 1000 times higher than the current systems in 10 years. Motivated by this common problem, there are several studies to integrate mm-wave access into current cellular networks as multi-band heterogeneous networks to exploit the ultra-wideband aspect of the mm-wave band. The authors of this paper have proposed comprehensive architecture of cellular networks with mm-wave access, where mm-wave small cell basestations and a conventional macro basestation are connected to Centralized-RAN (C-RAN) to effectively operate the system by enabling power efficient seamless handover as well as centralized resource control including dynamic cell structuring to match the limited coverage of mm-wave access with high traffic user locations via user-plane/control-plane splitting. In this paper, to prove the effectiveness of the proposed 5G cellular networks with mm-wave access, system level simulation is conducted by introducing an expected future traffic model, a measurement based mm-wave propagation model, and a centralized cell association algorithm by exploiting the C-RAN architecture. The numerical results show the effectiveness of the proposed network to realize 1000 times higher system rate than the current network in 10 years which is not achieved by the small cells using commonly considered 3.5 GHz band. Furthermore, the paper also gives latest status of mm-wave devices and regulations to show the feasibility of using mm-wave in the 5G systems.Comment: 17 pages, 12 figures, accepted to be published in IEICE Transactions on Communications. (Mar. 2015

Serious Game Engineering and Lighting Models for the Realistic Emulation of 5G Systems

[ES] La quinta generación de comunicaciones móviles, 5G, promete ser una revolución tecnológica que vaya más allá de multiplicar la velocidad de transmisión de datos de sus predecesoras. Pretende soportar una gran cantidad de dispositivos y alcanzar latencias muy cercanas a 1 milisegundo. Para satisfacer estos ambiciosos requisitos, se han investigado nuevas tecnologías habilitadoras. Una de ellas es el uso de las bandas de ondas milimétricas (mmW) en las cuales hay una gran cantidad de espectro disponible. Para predecir las características del canal radio y evaluar las prestaciones de la 5G de forma fiable en las bandas mmW se requieren modelos de canal complejos. Concretamente, los modelos de propagación más precisos son los basados en trazado de rayos, pero su alto costo computacional los hacen inviables para la caracterización del canal radio en escenarios complejos. Por otro lado, en los últimos años, la tecnología de videojuegos ha desarrollado potentes herramientas para modelar la propagación de la luz en escenarios superrealistas. Dada la cercanía espectral entre el espectro visible y las ondas mmW, la presente Tesis ha estudiado la aplicación de las herramientas de modelado de propagación de la luz de los motores de juego para el modelado del canal radio en mmW. Esta Tesis propone un modelo de estimación de las pérdidas de propagación en mmW llamado "Modelo de Intensidad de Luz'' (LIM). Usando este modelo, basado en los procesos de iluminación realizados por los motores de juego, los transmisores de señal se sustituyen por focos de luz y la intensidad lumínica recibida en un punto se traduce a potencia de señal en milimétricas a través de una función polinómica sencilla. Una de las ventajas de usar los motores de juego es su gran capacidad y la facilidad que tiene el usuario para crear escenarios superrealistas que representen fielmente la geometría de escenarios donde se quiera evaluar el canal radio. De esta forma se pueden obtener estimaciones precisas de las pérdidas de propagación. La estimación de las pérdidas de propagación con LIM ha sido comparada con campañas de medida en las bandas de 28 GHz y 73 GHz y con otros modelos de propagación. Como resultado, el error de estimación de LIM es menor que los modelos estocásticos actuales y es comparable con el modelo de trazado de rayos. Y, además, el coste computacional de LIM comparado con el trazado de rayos es 130 veces menor, lo que posibilita el uso de LIM en escenarios altamente complejos para la estimación del canal radio en tiempo real. Los motores de juego permiten caracterizar de forma diferente la interacción de los materiales con la luz configurando el mapa de normales de sus superficies y sus funciones de dispersión y reflexión. En esta Tesis se ha determinado la caracterización de varios materiales que mejor se ajusta a medidas de laboratorio realizadas en un escenario controlado en la banda de 28 GHz. El modelo de LIM empleando materiales con esta caracterización óptima reduce más de un 50\% su error de estimación con respecto a la aplicación de LIM con los materiales por defecto, mientras que su coste computacional sigue siendo 26 veces menor que el modelo de trazado de rayos. Finalmente, se ha desarrollado sobre un motor de juego una primera versión de plataforma para la emulación de los sistemas 5G que es el punto de partida para un emulador completo de 5G. Esta plataforma no sólo contiene el modelo de LIM sino que incluye varios casos de uso de la 5G en entornos superrealistas. La plataforma, que se basa en el concepto de "Serious Game Engineering", rompe las limitaciones de los simuladores de redes móviles en cuanto a las capacidades de visualización e interacción del usuario con los componentes de la red en tiempo real.[CA] La cinquena generació de comunicacions mòbils, 5G, promet ser una revolució tecnològica que vaja més enllà de multiplicar la velocitat de transmissió de dades de les seues predecessores. Pretén suportar una gran quantitat de dispositius i aconseguir latències molt pròximes a 1 mil·lisegon. Per a satisfer aquests ambiciosos requisits, s'han investigat noves tecnologies habilitadores. Una d'elles és l'ús de les bandes d'ones mil·limètriques (mmW) en les quals hi ha una gran quantitat d'espectre disponible. Per a predir les característiques del canal ràdio i avaluar les prestacions de la 5G de forma fiable en les bandes mmW es requereixen models de canal complexos. Concretament, els models de propagació més precisos són els basats en traçat de rajos, però el seu alt cost computacional els fan inviables per a la caracterització del canal ràdio en escenaris complexos. D'altra banda, en els últims anys, la tecnologia de videojocs ha desenvolupat potents eines per a modelar la propagació de la llum en escenaris superrealistes. Donada la proximitat espectral entre l'espectre visible i les ones mmW, la present Tesi ha estudiat l'aplicació de les eines de modelatge de propagació de la llum dels motors de joc per al modelatge del canal radie en mmW. Aquesta Tesi proposa un model d'estimació de les pèrdues de propagació en mmW anomenat "Model d'Intensitat de Llum'' (LIM). Usant aquest model, basat en els processos d'il·luminació realitzats pels motors de joc, els transmissors de senyal se substitueixen per focus de llum i la intensitat lumínica rebuda en un punt es tradueix a potència de senyal en mil·limètriques a través d'una funció polinòmica senzilla. Una dels avantatges d'usar els motors de joc és la seua gran capacitat i la facilitat que té l'usuari per a crear escenaris superrealistes que representen fidelment la geometria d'escenaris on es vulga avaluar el canal ràdio. D'aquesta forma es poden obtindre estimacions precises de les pèrdues de propagació. L'estimació de les pèrdues de propagació amb LIM ha sigut comparada amb campanyes de mesura en les bandes de 28~GHz i 73~GHz i amb altres models de propagació. Com a resultat, l'error d'estimació de LIM és menor que els models estocàstics actuals i és comparable amb el model de traçat de rajos. I, a més, el cost computacional de LIM comparat amb el traçat de rajos és 130 vegades menor, la qual cosa possibilita l'ús de LIM en escenaris altament complexos per a l'estimació del canal ràdio en temps real. Els motors de joc permeten caracteritzar de forma diferent la interacció dels materials amb la llum configurant el mapa de normals de les seues superfícies i les seues funcions de dispersió i reflexió. En aquesta Tesi s'ha determinat la caracterització de diversos materials que s'ajusta millor a mesures de laboratori realitzades en un escenari controlat en la banda de 28 GHz. El model de LIM emprant materials amb aquesta caracterització òptima redueix més d'un 50 % el seu error d'estimació respecte a l'aplicació de LIM amb els materials per defecte, mentre que el seu cost computacional continua sent 26 vegades menor que el model de traçat de rajos. Finalment, s'ha desenvolupat sobre un motor de joc una primera versió de plataforma per a l'emulació dels sistemes 5G que és el punt de partida per a un emulador complet de 5G. Aquesta plataforma no solament conté el model de LIM sinó que inclou diversos casos d'ús de la 5G en entorns superrealistes. La plataforma, que es basa en el concepte de "Serious Game Engineering", trenca les limitacions dels simuladors de xarxes mòbils quant a les capacitats de visualització i interacció de l'usuari amb els components de la xarxa en temps real.[EN] The fifth generation of mobile communications, 5G, promises to be a technological revolution that goes beyond multiplying the data transmission speed of its predecessors. It aims to support a large number of devices and reach latencies very close to 1 millisecond. To meet these ambitious requirements, new enabling technologies have been researched. One of these is the use of millimetre-wave bands (mmW) in which a large amount of spectrum is available. Complex channel models are required to predict radio channel characteristics and reliably evaluate 5G performance in the mmW bands. Specifically, the most accurate propagation models are those based on ray tracing, but their high computational cost makes them unfeasible for radio channel characterization in complex scenarios. On the other hand, in recent years, video game technology has developed powerful tools to model the propagation of light in super realistic scenarios. Given the spectral closeness between the visible spectrum and the mmW waves, the present Thesis has studied the application of light propagation modeling tools from game engines for radio channel modeling in mmW. This Thesis proposes a model for estimating propagation losses in mmW called "Light Intensity Model'' (LIM). Using this model, based on the lighting processes performed by the game engines, the signal transmitters are replaced by light sources and the light intensity received at a point is translated into signal strength in mmW through a simple polynomial function. One of the advantages of using the game engines is their great capacity and the ease with which the user can create super realistic scenarios that faithfully represent the geometry of scenarios where the radio channel is to be evaluated. In this way, accurate estimates of propagation losses can be obtained. The estimation of propagation losses with LIM has been compared with measurement campaigns in the 28 GHz and 73 GHz bands and with other propagation models. As a result, the LIM estimation error is smaller than the current stochastic models and is comparable with the ray tracing model. In addition, the computational cost of LIM compared to ray tracing is 130 times lower, allowing the use of LIM in highly complex scenarios for real-time radio channel estimation. The game engines allow to characterize in a different way the interaction of the materials with the light configuring the normal map of their surfaces and their scattering and reflection functions. In this Thesis it has been determined the characterization of several materials that best fits to laboratory measurements made in a controlled scenario in the 28 GHz band. The LIM model using materials with this optimal characterization reduces by more than 50% its estimation error with respect to the application of LIM with default materials, while its computational cost remains 26 times lower than the ray tracing model. Finally, a first version of a platform for the emulation of 5G systems has been developed on a game engine, which is the starting point for a complete 5G emulator. This platform not only contains the LIM model but also includes several 5G use cases in super realistic environments. The platform, which is based on the concept of "`Serious Game Engineering", breaks the limitations of mobile network simulators in terms of visualization capabilities and user interaction with network components in real time.Inca Sánchez, SA. (2019). Serious Game Engineering and Lighting Models for the Realistic Emulation of 5G Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/132695TESI

Contributions to channel modelling and performance estimation of HAPS-based communication systems regarding IEEE Std 802.16TM

New and future telecommunication networks are and will be broadband type. The existing terrestrial and space radio communication infrastructures might be supplemented by new wireless networks that make and will make use of aeronautics-technology. Our study/contribution is referring to radio communications based on radio stations aboard a stratospheric platform named, by ITU-R, HAPS (High Altitude Platform Station). These new networks have been proposed as an alternative technology within the ITU framework to provide various narrow/broadband communication services. With the possibility of having a payload for Telecommunications in an aircraft or a balloon (HAPS), it can be carried out radio communications to provide backbone connections on ground and to access to broadband points for ground terminals. The latest implies a complex radio network planning. Therefore, the radio coverage analysis at outdoors and indoors becomes an important issue on the design of new radio systems. In this doctoral thesis, the contribution is related to the HAPS application for terrestrial fixed broadband communications. HAPS was hypothesised as a quasi-static platform with height above ground at the so-called stratospheric layer. Latter contribution was fulfilled by approaching via simulations the outdoor-indoor coverage with a simple efficient computational model at downlink mode. This work was assessing the ITU-R recommendations at bands recognised for the HAPS-based networks. It was contemplated the possibility of operating around 2 GHz (1820 MHz, specifically) because this band is recognised as an alternative for HAPS networks that can provide IMT-2000 and IMT-Advanced services. The global broadband radio communication model was composed of three parts: transmitter, channel, and receiver. The transmitter and receiver parts were based on the specifications of the IEEE Std 802.16TM-2009 (with its respective digital transmission techniques for a robust-reliable link), and the channel was subjected to the analysis of radio modelling at the level of HAPS and terrestrial (outdoors plus indoors) parts. For the channel modelling was used the two-state characterisation (physical situations associated with the transmitted/received signals), the state-oriented channel modelling. One of the channel-state contemplated the environmental transmission situation defined by a direct path between transmitter and receiver, and the remaining one regarded the conditions of shadowing. These states were dependent on the elevation angle related to the ray-tracing analysis: within the propagation environment, it was considered that a representative portion of the total energy of the signal was received by a direct or diffracted wave, and the remaining power signal was coming by a specular wave, to last-mentioned waves (rays) were added the scattered and random rays that constituted the diffuse wave. At indoors case, the variations of the transmitted signal were also considering the following matters additionally: the building penetration, construction material, angle of incidence, floor height, position of terminal in the room, and indoor fading; also, these indoors radiocommunications presented different type of paths to reach the receiver: obscured LOS, no LOS (NLOS), and hard NLOS. The evaluation of the feasible performance for the HAPS-to-ground terminal was accomplished by means of thorough simulations. The outcomes of the experiment were presented in terms of BER vs. Eb/N0 plotting, getting significant positive conclusions for these kind of system as access network technology based on HAPS

Radio frequency channel characterization for energy harvesting in factory environments

This thesis presents ambient energy data obtained from a measurement campaign carried out at an automobile plant. At the automobile plant, ambient light, ambient temperature and ambient radio frequency were measured during the day time over two days. The measurement results showed that ambient light generated the highest DC power. For plant and operation managers at the automobile plant, the measurement data can be used in system design considerations for future energy harvesting wireless sensor nodes at the plant. In addition, wideband measurements obtained from a machine workshop are presented in this thesis. The power delay profile of the wireless channel was obtained by using a frequency domain channel sounding technique. The measurements were compared with an equivalent ray tracing model in order to validate the suitability of the commercial propagation software used in this work. Furthermore, a novel technique for mathematically recreating the time dispersion created by factory inventory in a radio frequency channel is discussed. As a wireless receiver design parameter, delay spread characterizes the amplitude and phase response of the radio channel. In wireless sensor devices, this becomes paramount, as it determines the complexity of the receiver. In reality, it is sometimes difficult to obtain full detail floor plans of factories for deterministic modelling or carry out spot measurements during building construction. As a result, radio provision may be suboptimal. The method presented in this thesis is based on 3-D fractal geometry. By employing the fractal overlaying algorithm presented, metallic objects can be placed on a floor plan so as to obtain similar radio frequency channel effects. The environment created using the fractal approach was used to estimate the amount of energy a harvesting device can accumulate in a University machine workshop space

Ondas milimétricas e MIMO massivo para otimização da capacidade e cobertura de redes heterogeneas de 5G

Today's Long Term Evolution Advanced (LTE-A) networks cannot support the exponential growth in mobile traffic forecast for the next decade. By 2020, according to Ericsson, 6 billion mobile subscribers worldwide are projected to generate 46 exabytes of mobile data traffic monthly from 24 billion connected devices, smartphones and short-range Internet of Things (IoT) devices being the key prosumers. In response, 5G networks are foreseen to markedly outperform legacy 4G systems. Triggered by the International Telecommunication Union (ITU) under the IMT-2020 network initiative, 5G will support three broad categories of use cases: enhanced mobile broadband (eMBB) for multi-Gbps data rate applications; ultra-reliable and low latency communications (URLLC) for critical scenarios; and massive machine type communications (mMTC) for massive connectivity. Among the several technology enablers being explored for 5G, millimeter-wave (mmWave) communication, massive MIMO antenna arrays and ultra-dense small cell networks (UDNs) feature as the dominant technologies. These technologies in synergy are anticipated to provide the 1000_ capacity increase for 5G networks (relative to 4G) through the combined impact of large additional bandwidth, spectral efficiency (SE) enhancement and high frequency reuse, respectively. However, although these technologies can pave the way towards gigabit wireless, there are still several challenges to solve in terms of how we can fully harness the available bandwidth efficiently through appropriate beamforming and channel modeling approaches. In this thesis, we investigate the system performance enhancements realizable with mmWave massive MIMO in 5G UDN and cellular infrastructure-to-everything (C-I2X) application scenarios involving pedestrian and vehicular users. As a critical component of the system-level simulation approach adopted in this thesis, we implemented 3D channel models for the accurate characterization of the wireless channels in these scenarios and for realistic performance evaluation. To address the hardware cost, complexity and power consumption of the massive MIMO architectures, we propose a novel generalized framework for hybrid beamforming (HBF) array structures. The generalized model reveals the opportunities that can be harnessed with the overlapped subarray structures for a balanced trade-o_ between SE and energy efficiently (EE) of 5G networks. The key results in this investigation show that mmWave massive MIMO can deliver multi-Gbps rates for 5G whilst maintaining energy-efficient operation of the network.As redes LTE-A atuais não são capazes de suportar o crescimento exponencial de tráfego que está previsto para a próxima década. De acordo com a previsão da Ericsson, espera-se que em 2020, a nível global, 6 mil milhões de subscritores venham a gerar mensalmente 46 exa bytes de tráfego de dados a partir de 24 mil milhões de dispositivos ligados à rede móvel, sendo os telefones inteligentes e dispositivos IoT de curto alcance os principais responsáveis por tal nível de tráfego. Em resposta a esta exigência, espera-se que as redes de 5a geração (5G) tenham um desempenho substancialmente superior às redes de 4a geração (4G) atuais. Desencadeado pelo UIT (União Internacional das Telecomunicações) no âmbito da iniciativa IMT-2020, o 5G irá suportar três grandes tipos de utilizações: banda larga móvel capaz de suportar aplicações com débitos na ordem de vários Gbps; comunicações de baixa latência e alta fiabilidade indispensáveis em cenários de emergência; comunicações massivas máquina-a-máquina para conectividade generalizada. Entre as várias tecnologias capacitadoras que estão a ser exploradas pelo 5G, as comunicações através de ondas milimétricas, os agregados MIMO massivo e as redes celulares ultradensas (RUD) apresentam-se como sendo as tecnologias fundamentais. Antecipa-se que o conjunto destas tecnologias venha a fornecer às redes 5G um aumento de capacidade de 1000x através da utilização de maiores larguras de banda, melhoria da eficiência espectral, e elevada reutilização de frequências respetivamente. Embora estas tecnologias possam abrir caminho para as redes sem fios com débitos na ordem dos gigabits, existem ainda vários desafios que têm que ser resolvidos para que seja possível aproveitar totalmente a largura de banda disponível de maneira eficiente utilizando abordagens de formatação de feixe e de modelação de canal adequadas. Nesta tese investigamos a melhoria de desempenho do sistema conseguida através da utilização de ondas milimétricas e agregados MIMO massivo em cenários de redes celulares ultradensas de 5a geração e em cenários 'infraestrutura celular-para-qualquer coisa' (do inglês: cellular infrastructure-to-everything) envolvendo utilizadores pedestres e veiculares. Como um componente fundamental das simulações de sistema utilizadas nesta tese é o canal de propagação, implementamos modelos de canal tridimensional (3D) para caracterizar de forma precisa o canal de propagação nestes cenários e assim conseguir uma avaliação de desempenho mais condizente com a realidade. Para resolver os problemas associados ao custo do equipamento, complexidade e consumo de energia das arquiteturas MIMO massivo, propomos um modelo inovador de agregados com formatação de feixe híbrida. Este modelo genérico revela as oportunidades que podem ser aproveitadas através da sobreposição de sub-agregados no sentido de obter um compromisso equilibrado entre eficiência espectral (ES) e eficiência energética (EE) nas redes 5G. Os principais resultados desta investigação mostram que a utilização conjunta de ondas milimétricas e de agregados MIMO massivo possibilita a obtenção, em simultâneo, de taxas de transmissão na ordem de vários Gbps e a operação de rede de forma energeticamente eficiente.Programa Doutoral em Telecomunicaçõe

Enhancing wireless communication system performance through modified indoor environments

This thesis reports the methods, the deployment strategies and the resulting system performance improvement of in-building environmental modification. With the increasing use of mobile computing devices such as PDAs, laptops, and the expansion of wireless local area networks (WLANs), there is growing interest in increasing productivity and efficiency through enhancing received signal power. This thesis proposes the deployment of waveguides consisting of frequency selective surfaces (FSSs) in indoor wireless environments and investigates their effect on radio wave propagation. The received power of the obstructed (OBS) path is attenuated significantly as compared with that of the line of sight (LOS) path, thereby requiring an additional link budget margin as well as increased battery power drain. In this thesis, the use of an innovative model is also presented to selectively enhance radio propagation in indoor areas under OBS conditions by reflecting the channel radio signals into areas of interest in order to avoid significant propagation loss. An FSS is a surface which exhibits reflection and/or transmission properties as a function of frequency. An FSS with a pass band frequency response was applied to an ordinary or modified wall as a wallpaper to transform the wall into a frequency selective (FS) wall (FS-WALL) or frequency selective modified wall (FS-MWALL). Measurements have shown that the innovative model prototype can enhance 2.4GHz (IEEE 802.11b/g/n) transmissions in addition to the unmodified wall, whereas other radio services, such as cellular telephony at 1.8GHz, have other routes to penetrate or escape. The FSS performance has been examined intensely by both equivalent circuit modelling, simulation, and practical measurements. Factors that influence FSS performance such as the FSS element dimensions, element conductivities, dielectric substrates adjacent to the FSS, and signal incident angles, were investigated. By keeping the elements small and densely packed, a largely angle-insensitive FSS was developed as a promising prototype for FSS wallpaper. Accordingly, the resultant can be modelled by cascading the effects of the FSS wallpaper and the ordinary wall (FSWALL) or modified wall (FS-MWALL). Good agreement between the modelled, simulated, and the measured results was observed. Finally, a small-scale indoor environment has been constructed and measured in a half-wave chamber and free space measurements in order to practically verify this approach and through the usage of the deterministic ray tracing technique. An initial investigation showing that the use of an innovative model can increase capacity in MIMO systems. This can be explained by the presence of strong multipath components which give rise to a low correlated Rayleigh Channel. This research work has linked the fields of antenna design, communication systems, and building architecture