Massive MIMO channel modelling for 5G wireless communication systems

Massive Multiple-Input Multiple-Output (MIMO) wireless communication systems, equipped with tens or even hundreds of antennas, emerge as a promising technology for the Fifth Generation (5G) wireless communication networks. To design and evaluate the performance of massive MIMO wireless communication systems, it is essential to develop accurate, flexible, and efficient channel models which fully reflect the characteristics of massive MIMO channels. In this thesis, four massive MIMO channel models have been proposed. First, a novel non-stationary wideband multi-confocal ellipse Two-Dimensional (2-D) Geometry Based Stochastic Model (GBSM) for massive MIMO channels is proposed. Spherical wavefront is assumed in the proposed channel model, instead of the plane wavefront assumption used in conventional MIMO channel models. In addition, the Birth-Death (BD) process is incorporated into the proposed model to capture the dynamic properties of clusters on both the array and time axes. Second, we propose a novel theoretical non-stationary Three-Dimensional (3-D) wideband twin-cluster channel model for massive MIMO communication systems with carrier frequencies in the order of gigahertz (GHz). As the dimension of antenna arrays cannot be ignored for massive MIMO, nearfield effects instead of farfield effects are considered in the proposed model. These include the spherical wavefront assumption and a BD process to model non-stationary properties of clusters such as cluster appearance and disappearance on both the array and time axes. Third, a novel Kronecker Based Stochastic Model (KBSM) for massive MIMO channels is proposed. The proposed KBSM can not only capture antenna correlations but also the evolution of scatterer sets on the array axis. In addition, upper and lower bounds of KBSM channel capacities in both the high and low Signal-to-Noise Ratio (SNR) regimes are derived when the numbers of transmit and receive antennas are increasing unboundedly with a constant ratio. Finally, a novel unified framework of GBSMs for 5G wireless channels is proposed. The proposed 5G channel model framework aims at capturing key channel characteristics of certain 5G communication scenarios, such as massive MIMO systems, High Speed Train (HST) communications, Machine-to-Machine (M2M) communications, and Milli-meter Wave (mmWave) communications

On geometry-base statistical channel models for MIMO wireles communications

El uso de sistemas de comunicación de banda ancha de múltiple entradamúltiple salida (Multiple Input Multiple Output MIMO) es actualmente objeto de un interés considerable. Una razón para esto es el reciente desarrollo de sistemas de comunicación móvil de tercera generación (3G) y superiores, tales como la tecnología de banda ancha Wideband Code Division Multiple Access (WCDMA, por sus siglas en inglés), la cual proporciona canales de radio de 5 MHz de ancho de banda. Para el diseño y la simulación de estos sistemas de radio móviles que usan propagación inalámbrica MIMO (como Wideband-CDMA por ejemplo), necesitamos modelos de canal que provean la requerida información espacial y temporal necesaria para el estudio de tales sistemas, esto es, los parámetros básicos de modelado en los dominios del espacio y el tiempo. Como ejemplo podemos mencionar, el valor cuadrático medio de la dispersión del retardo (Delay spread DS) el cual está directamente relacionado a la capacidad de un sistema de comunicación específico y nos da una idea aproximada de la complejidad del receptor. En esta tesis, se propone un modelo basado en geometría con enfoque en grupos (clusters) y es utilizado para el análisis en los dominios del espacio y el tiempo para condiciones estacionarias, y para representar los perfiles de potencia-angulo-retardo (Power Delay Angle Profiles PDAPs) de los componentes multi-trayectoria en ambientes urbanos. Además, se han derivado soluciones en formas cerradas para las expresiones en el dominio del ángulo (espacial) y del tiempo. La investigación previa sobre el modelado de canales cubre una amplia variedad de aspectos en varios niveles de detalle, incluyendo análisis para condiciones no estacionarias. Sin embargo el trabajo presentado en la literatura no incluye las relaciones entre los grupos (cluster) físicos y los PDAPs. El modelo propuesto basado en grupos (clusters) puede ser usado para mejorar aún más el desempeño en condiciones estacionarias de los sistemas de comunicaciones móviles actuales y futuros tales como los sistemas de comunicación MIMO de banda ancha. En la tesis también se presenta un análisis en el dominio del ángulo (espacial) y del tiempo respectivamente, a través de las funciones densidad de probabilidad (PDF) de la dirección de llegada (Direction of Arrival DOA) y el tiempo de llegada (Time of Arrival TOA) para el modelo basado en grupos. A fin de evaluar las funciones de probabilidad teóricas derivadas, éstas han sido comparadas con resultados experimentales publicados en la literatura. La comparación con estos resultados experimentales muestran una buena concordancia, no obstante la técnica de modelado presentada en esta tesis se encuentra limitada a condiciones estacionarias del canal. La condición de no estacionariedad se ubica más allá del alcance de esta tesis, es decir, el modelo propuesto no incorpora el efecto Doppler en los análisis

Terahertz Wireless Channels: A Holistic Survey on Measurement, Modeling, and Analysis

Terahertz (0.1-10 THz) communications are envisioned as a key technology for sixth generation (6G) wireless systems. The study of underlying THz wireless propagation channels provides the foundations for the development of reliable THz communication systems and their applications. This article provides a comprehensive overview of the study of THz wireless channels. First, the three most popular THz channel measurement methodologies, namely, frequency-domain channel measurement based on a vector network analyzer (VNA), time-domain channel measurement based on sliding correlation, and time-domain channel measurement based on THz pulses from time-domain spectroscopy (THz-TDS), are introduced and compared. Current channel measurement systems and measurement campaigns are reviewed. Then, existing channel modeling methodologies are categorized into deterministic, stochastic, and hybrid approaches. State-of-the-art THz channel models are analyzed, and the channel simulators that are based on them are introduced. Next, an in-depth review of channel characteristics in the THz band is presented. Finally, open problems and future research directions for research studies on THz wireless channels for 6G are elaborated.Comment: to appear in IEEE Communications Surveys and Tutorial

Pogodnosti i izazovi determinističkog referentnog modela radijskog kanala

The paper introduces a new paradigm for reference channel models. Current reference channel models are designed as platforms that generate radio channels for testing using random values for their parameters. These parameters follow some pre-established distribution based on process called parameterization, i.e. statistical processing of previous real measurements or accurate ray tracing simulations. The paper argues that random generated channels give either no new insight or even delusive information and should be replaced with the initial set of radio channels that was used for parameterization. Therefore a deterministic reference channel model, as an emulator of previously recorded real radio channels, is proposed and its potential elaborated.U radu se uvodi nova paradigma za referentni model radijskog kanala. Postojeći referentni modeli radijskog kanala dizajnirani su kao platforma koja generira radio kanale za testiranje pomoću slučajnih vrijednosti za svoje parametre. Ovi parametri prate neke unaprijed utvrđene raspodjele koje potječu iz procesa parametrizacije, odnosno statističke obrade prethodnih mjerenja ili točnih simulacija metodom slijeđenja zrake. U radu se tvrdi da slučajno generirani kanali ili ne daju nove uvide ili čak daju obmanjujuće informacije i valja ih zamijeniti s početnim skupom radijskih kanala koji je korišten za parametrizaciju. Stoga je predložen deterministički referentni model radijskog kanala, kao emulator prethodno snimljenih stvarnih radio kanala, te je njegov potencijal razrađen

Analysis of Channel Measurements Using a Very Large Antenna Array

Accurate wireless channel models are crucial to simulate the effect of radio wave propagation in a channel on wireless communication systems. By calculating physical processing effects that signal undergoes while traveling from transmitter to the receiver, channel models help to analyze performance of wireless systems. State of the art channel model such as WINNER and COST 2100 are able to model the characteristics of conventional MIMO (Multiple-Input Multiple-Output) systems (where moderate number of antennas is used at the two sides of the link) with sufficient accuracy. However, model extensions are needed for the current models in order to be able to capture new propagation characteristics result from having massive number of antenna elements at one or both ends of the communication link. In this thesis work, a measurement campaign is performed using very large antenna array (about 7.5m long) in order to study key propagation characteristics for massive MIMO. The channel measurements are performed using two frequency bands (2.6 GHz and 5.1 GHz), vertical and horizontal antenna polarizations, directional and omni-directional antennas. Effect of aforementioned setup parameters on cluster delay and angle spreads, power slope and shadowing, number of clusters and their observation lengths are studied in this work. Also correlation among estimated cluster parameters is presented. It was observed, that antenna polarization does not have significant effect on estimated cluster parameters. On the other hand, some estimated parameters like delay and angle spread, shadowing achieve higher values using 2.6 GHz band. Impact of antenna directivity was not very significant. Results of this thesis work are important while implementing extension for cluster-based COST 2100 channel model for massive MIMO case

Channel Modeling and Characteristics for 6G Wireless Communications

[EN] Channel models are vital for theoretical analysis, performance evaluation, and system deployment of the communication systems between the transmitter and receivers. For sixth-generation (6G) wireless networks, channel modeling and characteristics analysis should combine different technologies and disciplines, such as high-mobil-ity, multiple mobilities, the uncertainty of motion trajectory, and the non-stationary nature of time/frequency/space domains. In this article, we begin with an overview of the salient characteristics in the modeling of 6G wireless channels. Then, we discuss the advancement of channel modeling and characteristics analysis for next-generation communication systems. Finally, we outline the research challenges of channel models and characteristics in 6G wireless communications.This research was supported by the National Key R&D Program of China under grant 2018YFB1801101; the National Nature Science Foundation of China (No. 61771248 and 61971167); the Jiangsu Province Research Scheme of Nature Science for Higher Education Institution (No. 14KJA510001); and the Open Research Fund of the National Mobile Communications Research Laboratory, Southeast University (No. 2020D14).Jiang, H.; Mukherjee, M.; Zhou, J.; Lloret, J. (2021). Channel Modeling and Characteristics for 6G Wireless Communications. IEEE Network. 35(1):296-303. https://doi.org/10.1109/MNET.011.200034829630335