Measurement Based Channel Characterization and Modeling for Vehicle-to-Vehicle Communications

Vehicle-to-Vehicle (V2V) communication is a challenging but fast growing technology that has potential to enhance traffic safety and efficiency. It can also provide environmental benefits in terms of reduced fuel consumption. The effectiveness and reliability of these applications highly depends on the quality of the V2V communication link, which rely upon the properties of the propagation channel. Therefore, understanding the properties of the propagation channel becomes extremely important. This thesis aims to fill some gaps of knowledge in V2V channel research by addressing four different topics. The first topic is channel characterization of some important safety critical scenarios (papers I and II). Second, is the accuracy or validation study of existing channel models for these safety critical scenarios (papers III and IV). Third, is about channel modeling (paper V) and, the fourth topic is the impact of antenna placement on vehicles and the possible diversity gains. This thesis consists of an introduction and six papers: Paper I presents a double directional analysis of vehicular channels based on channel measurement data. Using SAGE, a high-resolution algorithm for parameter estimation, we estimate channel parameters to identify underlying propagation mechanisms. It is found that, single-bounce reflections from static objects are dominating propagation mechanisms in the absence of line-of-sight (LOS). Directional spread is observed to be high, which encourages the use of diversity-based methods. Paper II presents results for V2V channel characterization based on channel measurements conducted for merging lanes on highway, and four-way street intersection scenarios. It is found that the merging lane scenario has the worst propagation condition due to lack of scatterers. Signal reception is possible only with the present LOS component given that the antenna has a good gain in the direction of LOS. Thus designing an antenna that has an omni-directional gain, or using multiple antennas that radiate towards different directions become more important for such safety critical scenarios. Paper III presents the results of an accuracy study of a deterministic ray tracing channel model for vehicle-to-vehicle (V2V) communication, that is compared against channel measurement data. It is found that the results from measurement and simulation show a good agreement especially in LOS situations where as in NLOS situations the simulations are accurate as far as existing physical phenomena of wave propagation are captured by the implemented algorithm. Paper IV presents the results of a validation study of a stochastic NLOS pathloss and fading model named VirtualSource11p for V2V communication in urban street intersections. The reference model is validated with the help of independent channel measurement data. It is found that the model is flexible and fits well to most of the measurements with a few exceptions, and we propose minor modifications to the model for increased accuracy. Paper V presents a shadow fading model targeting system simulations based on channel measurements. The model parameters are extracted from measurement data, which is separated into three categories; line-of-sight (LOS), LOS obstructed by vehicles (OLOS), and LOS blocked by buildings (NLOS), with the help of video information recorded during the measurements. It is found that vehicles obstructing the LOS induce an additional attenuation in the received signal power. The results from system level vehicular ad hoc network (VANET) simulations are also presented, showing that the LOS obstruction affects the packet reception probability and this can not be ignored. Paper VI investigates the impact of antenna placement based on channel measurements performed with four omni-directional antennas mounted on the roof, bumper, windscreen and left-side mirror of the transmitter and receiver cars. We use diversity combining methods to evaluate the performance differences for all possible single-input single-output (SIMO), multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) link combinations. This investigation suggests that a pair of antennas with complementary properties, e.g., a roof mounted antenna together with a bumper antenna is a good solution for obtaining the best reception performance, in most of the propagation environments. In summary, this thesis describes the channel behavior for safety-critical scenarios by statistical means and models it so that the system performance can be assessed in a realistic manner. In addition to that the influence of different antenna arrangements has also been studied to exploit the spatial diversity and to mitigate the shadowing effects. The presented work can thus enable more efficient design of future V2V communication systems

Channel Measurements and Modeling for Dynamic Vehicular ISAC Scenarios at 28 GHz

Integrated sensing and communication (ISAC) is a promising technology for 6G, with the goal of providing end-to-end information processing and inherent perception capabilities for future communication systems. Within ISAC emerging application scenarios, vehicular ISAC technologies have the potential to enhance traffic efficiency and safety through integration of communication and synchronized perception abilities. To establish a foundational theoretical support for vehicular ISAC system design and standardization, it is necessary to conduct channel measurements, and modeling to obtain a deep understanding of the radio propagation. In this paper, a dynamic statistical channel model is proposed for vehicular ISAC scenarios, incorporating Sensing Multipath Components (S-MPCs) and Clutter Multipath Components (C-MPCs), which are identified by the proposed tracking algorithm. Based on actual vehicular ISAC channel measurements at 28 GHz, time-varying sensing characteristics in front, left, and right directions are investigated. To model the dynamic evolution process of channel, number of new S-MPCs, lifetimes, initial power and delay positions, dynamic variations within their lifetimes, clustering, power decay, and fading of C-MPCs are statistically characterized. Finally, the paper provides implementation of dynamic vehicular ISAC model and validates it by comparing key simulation statistics between measurements and simulations

Enabling Accurate Cross-Layer PHY/MAC/NET Simulation Studies of Vehicular Communication Networks

Vehicle-to-vehicle and vehicle-to-roadside communications is required for numerous applications that aim at improving traffic safety and efficiency. In this setting, however, gauging system performance through field trials can be very expensive especially when the number of studied vehicles is high. Therefore, many existing studies have been conducted using either network or physical layer simulators; both approaches are problematic. Network simulators typically abstract physical layer details (coding, modulation, radio channels, receiver algorithms, etc.) while physical layer ones do not consider overall network characteristics (topology, network traffic types, and so on). In particular, network simulators view a transmitted frame as an indivisible unit, which leads to several limitations. First, the impact of the vehicular radio channel is typically not reflected in its appropriate context. Further, interference due to frame collisions is not modeled accurately ( if at all) and, finally, the benefits of advanced signal processing techniques, such as interference cancellation, are difficult to assess. To overcome these shortcomings we have integrated a detailed physical layer simulator into the popular NS-3 network simulator. This approach aims to bridge the gap between the physical and network layer perspectives, allow for more accurate channel and physical layer models, and enable studies on cross-layer optimization. In this paper, we exemplify our approach by integrating an IEEE 802.11a and p physical layer simulator with NS-3. Further, we validate the augmented NS-3 simulator against an actual IEEE 802.11 wireless testbed and illustrate the additional value of this integration

Modelling and Analysis of Non-Stationary Mobile Fading Channels Using Brownian Random Trajectory Models

Doktorgradsavhandling i informasjons- og kommunikasjonsteknologi, Universitetet i Agder, Grimstad, 2014The demanding mobility features of communication technologies call for the need to advance channel models (among other needs), in which non-stationary aspects of the channel are carefully taken into consideration. Owing to the mathematical complexity imposed by mobility features of the mobile station (MS), the number of non-stationary channel models proposed in the literature is very limited. The absence of a robust trajectory model for capturing the mobility features of the MS also adds to the depth of this gap. Not only statistically non-stationary channels, but also physically non-stationary channels, such as vehicle-to-vehicle channels in the presence of moving scatterers, have been rarely investigated. In the literature, there exist two fundamental channel modelling approaches, namely deterministic and stochastic approaches. Deterministic approaches, such as measurement-based channel modelling, are known to be accurate, but site-specific and economically expensive. The stochastic approaches, such as geometry-based channel modelling, are known to be economically inexpensive, computationally fair, but not as accurate as the deterministic approach. Among these approaches, the geometry-based stochastic approach is the best to capture the non-stationary aspects of the channel. In this dissertation, we employ the geometry-based stochastic approach for the development of three types of channel models, namely stationary, physically nonstationary, and statistically non-stationary channel models. We geometrically track the plane waves emitted from the transmitter over the local scatterers up to the receiver, which is assumed to be in motion. Under the assumptions that the scatterers are fixed and the observation time is short enough, we develop the stationary channel models. In this regard, we propose a unified disk scattering model (UDSM), which unifies several well-established geometry-based channel models into one robust channel model. We show that the UDSM is highly flexible and outperforms several other geometric models in the sense of matching empirical data. In addition, we provide a new approach to develop stationary channel models based on delay-angle joint distribution functions. Under the assumption that the scatterers are in motion and the observation time is again short enough, we develop a physically non-stationary channel model. In this connection, we model vehicle-to-vehicle (V2V) channels in the presence of moving scatterers. Proper distributions for explaining the speed of relatively fast and relatively slow moving scatterers are provided. The statistical properties of the proposed channel model are also derived and validated by measured channels. It is shown that relatively fast moving scatterers have a major impact on both V2V and fixed-to-fixed (F2F) communication links, as they are significant sources of the Doppler spread. However, relatively slow moving scatterers can be neglected in V2V channels, but not in F2F channels. Under the assumption that the scatterers are fixed and the observation time is not necessarily short anymore, we develop the statistically non-stationary channel models. To this aim, we first introduce a new approach for generating fully spatial random trajectories, which are supposed to capture the mobility features of the MS. By means of this approach, we develop a highly flexible trajectory model based on the primitives of Brownian fields (BFs). We show that the flexibility of the proposed trajectory is threefold: 1) its numerous configurations; 2) its smoothness control mechanism; and 3) its adaptivity to different speed scenarios. The statistical properties of the trajectory model are also derived and validated by data collected from empirical studies. We then introduce a new approach to develop stochastic non-stationary channel models, the randomness of which originates from a random trajectory of the MS, rather than from the scattering area. Based on the new approach, we develop and analyze a non-stationary channel model using the aforementioned Brownian random trajectory model. We show that the channel models developed by this approach are very robust with respect to the number of scatterers, such that highly reported statistical properties can be obtained even if the propagation area is sparsely seeded with scatterers. We also show that the proposed non-stationary channel model superimposes large-scale fading and small-scale fading. Moreover, we show that the proposed model captures the path loss effect. More traditionally, we develop and analyze two non-stationary channel models, the randomness of which originates from the position of scatterers, but not from the trajectory of the MS. Nevertheless, the travelling path of the MS is still determined by a sample function of a Brownian random trajectory. It is shown that the proposed channel models result in a twisted version of the Jakes power spectral density (PSD) that varies in time. Accordingly, it is demonstrated that non-stationarity in time is not in line with the common isotropic propagation assumption on the channel

Robust Low-Cost Multiple Antenna Processing for V2V Communication

Cooperative V2V communication with frequent, periodic broadcast of messages between vehicles is a key enabler of applications that increase traffic safety and traffic efficiency on roads. Such broadcast V2V communication requires an antenna system with omnidirectional coverage, which is difficult to achieve using a single antenna element. For a mounted, omnidirectional antenna on a vehicle is distorted by the vehicle body, and exhibits a nonuniform directional pattern with low gain in certain directions. The thesis addresses this problem by developing schemes that employ multiple antennas (MAs) to achieve an effective radiation pattern with omnidirectional characteristics at both the transmit- and the receive-side. To ensure robust communication, the MA schemes are designed to minimize the burst error probability of several consecutive status messages in a scarce multipath environment with a dominant path between vehicles.First, at the receive-side, we develop a hybrid analog-digital antenna combiner. The analog part of the combiner is composed of low-cost analog combining networks (ACNs) of phase shifters that do not depend on channel stateinformation (CSI), while the digital part uses maximal ratio combining. We show that the optimal phase slopes of the analog part of the combiner (i.e., the phase slopes that minimize the burst error probability) are the same found under the optimization of a single ACN, which was done in earlier work. We then show how directional antennas can be employed in this context to achieve an effective omnidirectional radiation pattern of the antenna system that is robust in all directions of arrival of received signals.Secondly, at the transmit-side, we develop two low-cost analog MA schemes, an analog beamforming network (ABN) of phase shifters, and an antenna switching network (ASN), for the case when receivers employ the ACN or the hybrid combiner. Both schemes are shown to achieve an effective radiation pattern with improved omnidirectional characteristics at the transmit-side without relying on CSI.Thirdly, the schemes above were developed assuming that all vehicles broadcast their messages with the same fixed period. Therefore, we tackle the practical scenario when different vehicles use different and potentially varying broadcast periods. We show that the phase slopes of the MA schemes at the receiver and/or transmitter can be designed to support multiple broadcast periods.\ua0Lastly, the optimal phase slopes of the MA schemes were analytically derived under a worst-case propagation corresponding to a dominant path with an angle of departure, and an angle of arrival that are approximately non-varying over the time it takes to transmit and receive several packets. We relax this assumption and study the system performance under a time-varying dominant component instead. We derive a design rule that yields robust phase slopes that effectively mitigate the losses due to the time-variation of the dominant path

Millimeter wave radio channels: properties, multipath modeling and simulations

Based on the characterization of realistic radio channels, results presented in this dissertation lead towards an understanding that when moving up to the higher frequencies, frequency itself does not play a significant role in defining the channel modeling methodology. In fact, how a propagation channel is illuminated is of fundamental importance. Therefore, millimeter wave (mmWave) system properties such as a high antenna directivity and system bandwidth are shown to have a great influence on the channel model definition. In this thesis, a fundamental assumption made in the state-of-the-art millimeter wave wireless channel models is challenged. It has been shown that Rayleigh-Rice fading assumption made in the state-of-the-art channel models for resolvable channel taps does not remain valid. This is mainly due to the sparse multipath illumination caused by high antenna directivity and high bandwidth of a mmWave system.Studies presented in this thesis are based on the characterization of realistic radio channels obtained from exhaustive channel sounding campaigns. Mainly, three fundamental problems of wireless channel modelling have been investigated for millimetre wave (mmWave) radio channel modelling application, namely (i) Frequency dependence of propagation, (ii) Impact of antenna directivity on the channel model definition, and (iii) Impact of system bandwidth on the radio channel modelling. A detailed description of these problems is as follows: (i) Frequency Dependence of Propagation. Multi-band measurement campaigns arecarried out using directional antennas which do an omni-directional scan of the propagation environment. During the measurements, Tx-Rx systems are placed at fixed positions and the propagation environment remained as static as possible. Using synthesized omni-directional power delay profiles (PDPs), we aim to investigate if there exists a frequency dependency in the multipath dispersion statistics, e.g. delay and angular spreads. (ii) Impact of Antenna Directivity on the Channel Model Definition. Small-scale fading measurements are carried out which emulate a scenario, where a radio communication link is established through a single multipath cluster which is illuminated using antennas with different Half Power Beam Widths (HPBW). The major goal here is to investigate the impact of spatial multipath filtering on the small-scale fading due to high antenna directivity. In particular, the impact on variations in the receive signal strength and the validity of narrowband wide-sense stationary assumption (both in time and frequency domains) is investigated. (iii) Impact of System Bandwidth on the Radio Channel Modelling. Small-scale fading measurements are used to illuminate multipath clusters in a lecture room scenario. The primary objective is to investigate the impact of high system bandwidth on variations in the receive signal strength, randomness in the cross-polarization power ratio (XPR) and richness of the multipath scattering. Based on the characterization of realistic radio channels, results presented in this dissertation lead towards an understanding that when moving up to the higher frequencies, frequency itself does not play a significant role in defining the channel modelling methodology. In fact, how a propagation channel is illuminated is of fundamental importance. Therefore, mmWave system properties such as a high antenna directivity and system bandwidth are shown to have a high influence on the channel model definition. In general, fade depth scaling as a function of system bandwidth is quite well understood. We demonstrate that, the high antenna directivity of mmWave systems result in a further reduction in the fading depth. In addition, we explore some new directions to this line of research which are based on the second-order statistical analysis of the channel impulse response (CIR) vector. Our results emphasize that, fading statistics of resolvable channel taps in a mmWave radio channel cannot be modelled as Rayleigh-Rice distributed random variables. This is primarily due to the fact that channels with sparse scattering conditions are illuminated due to high antenna directivity and bandwidth of mmWave systems. Consequently, the complex Gaussian random variable assumption associated with Rayleigh-Rice fading distributions does not remain valid. Further, it has been demonstrated that, high antenna directivity and bandwidth of mmWave systems also raise a question mark on the validity of wide-sense stationary (WSS) assumption in the slow-time domain of mmWave radio channels. Results presented in this contribution are novel and they provide theoretically consistent insights into the measured radio channel.In dieser Arbeit werden drei grundlegende Probleme der Modellierung von Drahtloskanalen fur die Anwendung bei der Funkkanalmodellierung im Millimeterwellenbereich (mmWave) untersucht, namlich (i) die Frequenzabhangigkeit der Ausbreitung, (ii) der Einfluss der Antennenrichtwirkung auf die Definition des Kanalmodells und (iii) der Einfluss der Systembandbreite auf die Funkkanalmodellierung. Die detaillierte Beschreibung dieser Probleme lautet wie folgt: (i) Frequenzabhangigkeit der Ausbreitung. Mehrband-Messkampagnen werden mitRichtantennen durchgefuhrt, die eine omnidirektionale Abtastung der Ausbreitungsumgebung vornehmen. Wahrend der Messungen werden die Tx-Rx-Systeme an festen Positionen platziert und die Ausbreitungsumgebung bleibt so statisch wie moglich. Mit Hilfe von synthetisierten omnidirektionalen Verzogerungs-Leistungsprofilen soll untersucht werden, ob es eine Frequenzabhangigkeit in der Mehrwegeausbreitungsstatistik gibt, z.B. in der Verzogerung und der Winkelspreizung. (ii) Einfluss der Antennenrichtwirkung auf die Definition des Kanalmodells. Es werden Messungen des schnellen Schwunds durchgefuhrt, die ein Szenario emulieren, bei dem eine Funkverbindung uber ein einzelnes Mehrwege-Cluster aufgebaut wird, das mit Antennen mit unterschiedlichen Strahlbreiten ausgeleuchtet wird. Das Hauptzielist hier die Untersuchung des Einflusses der raumlichen Filterung auf den schnellen Schwund aufgrund der hohen Antennenrichtwirkung. Insbesondere wird die Auswirkung auf Variationen der Empfangssignalstarke und die Gultigkeit der Annahme der schmalbandigen Stationaritat im weiteren Sinne (sowohl im Zeit- als auch im Frequenzbereich) untersucht. (iii) Einfluss der Systembandbreite auf die Funkkanalmodellierung. Messungen desschnellen Schwunds werden verwendet, um Mehrwege-Cluster in einem Horsaal-Szenario auszuleuchten. Das primare Ziel ist es, den Einfluss einer hohen Systembandbreite auf die Variationen der Empfangssignalstarke, die Zufalligkeit des Kreuzpolarisationsverhaltnisses und die Reichhaltigkeit der Mehrwegstreuung zu untersuchen. Basierend auf der Charakterisierung realistischer Funkkanäle führen die in dieser Dissertation vorgestellten Ergebnisse zu dem Verständnis, dass beim Ubergang zu höheren Frequenzen die Frequenz x selbst keine signifikante Rolle bei der Definition der Kanalmodellierungsmethodik spielt. Vielmehr ist es von grundlegender Bedeutung, wie ein Ausbreitungskanal ausgeleuchtet wird. Daher zeigt sich, dass mmWave-Systemeigenschaften wie eine hohe Antennenrichtcharakteristik und Systembandbreite einen hohen Einfluss auf die Definition des Kanalmodells haben. Im Allgemeinen ist die Skalierung der Schwundtiefe als Funktion der Systembandbreite ziemlich gut verstanden. Wir zeigen, dass die hohe Antennenrichtwirkung von mmWave-Systemen zu einer weiteren Reduzierung der Schwundtiefe führt. Zusätzlich erforschen wir einige neue Richtungen in diesem Forschungsbereich, die auf der Analyse der Statistik zweiter Ordnung des Kanalimpulsantwort-Vektors basieren. Unsere Ergebnisse unterstreichen, dass die Schwund-Statistiken der auflösbaren Kanalabgriffe in einem mmWave-Funkkanal nicht als Rayleigh-Rice-verteilte Zufallsvariablen modelliert werden können. Dies liegt vor allem daran, dass durch die hohe Antennenrichtwirkung und Bandbreite von mmWave-Systemen Kanale mit spärlichen Streubedingungen ausgeleuchtet werden. Folglich ist die Annahme komplexer Gaus’scher Zufallsvariablen, die mit Rayleigh-Rice Schwundverteilungen verbunden ist, nicht mehr gültig. Des Weiteren wird gezeigt, dass die hohe Antennenrichtwirkung und Bandbreite von mmWave-Systemen auch die Gültigkeit der Annahme von Stationarität im weiteren Sinne im Slow-Time-Bereich von mmWave-Funkkanälen in Frage stellt. Die in diesem Beitrag vorgestellten Ergebnisse sind neuartig und bieten theoretisch konsistente Einblicke in den gemessenen Funkkanal

Performance investigation of spatial modulation systems under realistic channel models

In order to fulfil the explosive demand for convenient wireless data access, novel wireless technologies such as the multiple-input-multiple-output (MIMO) have widely been used to improve the link reliability and capacity of wireless communication systems. In recent years, a new MIMO technology named the spatial modulation (SM) has attracted signi cant research interest due to its reported enhancement on the system performance with the reasonable system complexity. Before a new technology comes into real use, it is necessary to comprehensively evaluate its performance under different scenarios. In this thesis, we investigate the performance of SM systems under some important realistic scenarios for future wireless communications, such as the vehicle-to-vehicle (V2V), the high-speed train (HST), and the massive MIMO scenarios. Firstly, the bit error rate (BER) performance of SM systems under a novel threedimensional (3D) geometry based stochastic model (GBSM) for V2V MIMO channels is investigated by both theoretical analysis and system simulations. The impacts of vehicle tra c density (VTD), Doppler effect, and 3D feature on the BER performance of SM systems are thoroughly studied. In addition, other MIMO technologies, such as the vertical Bell Labs layered space-time (V-BLAST), the Alamouti scheme are compared with SM under different simulation settings. Secondly, the BER performance of SM systems is studied under a non-stationary wideband HST GBSM considering the non-ideal channel estimation case. The timevarying behaviour of the channel and its impact on the performance of SM systems are comprehensively investigated. The accurate theoretical BER expression of SM systems under a non-stationary wideband HST channels with non-ideal channel estimation is derived. A novel statistic property named stationary interval in terms of the space-time correlation function (STCF) is introduced in order to clearly explain all theoretical and simulation results. Thirdly, the performance of SM systems is evaluated under a Kroneck-based massive MIMO channel model. As a massive MIMO system employs large numbers of antennas, antenna elements are distributed over a wide range. Thus, different antenna elements may observe different sets of clusters. How this phenomenon affects the performance of SM systems is investigated by considering a survival probability of clusters, which abstracts the birth-death process of each cluster in the channel model. Moreover, the performance of SM systems is also compared with that of other MIMO technologies under the massive MIMO channel model. In summary, all research works in this thesis have considered realistic MIMO channel models, which are meaningful for the test, performance evaluation, and implementation of SM technology for future advanced wireless communications systems

Characterization, Avoidance and Repair of Packet Collisions in Inter-Vehicle Communication Networks

This work proposes a combined and accurate simulation of wireless channel, physical layer and networking aspects in order to bridge the gaps between the corresponding research communities. The resulting high fidelity simulations enable performance optimizations across multiple layers, and are used in the second part of this thesis to evaluate the impact of fast-fading channel characteristics on Carrier-Sense Multiple Access, and to quantify the benefit of successive interference cancellation

Extending TDL based non-WSSUS vehicle-to-everything channel model

In den vergangenen Jahrzehnten haben drahtlose Kommunikationssysteme eine rasante Entwicklung durchgemacht und es wurden viele Untersuchungen durchgeführt, seit Maxwell die Existenz von elektromagnetischer Wellen vorausgesagt hat. In den letzten Jahren hat die Forschung im Bereich der vehicle to X (V2X)-Kommunikation stetig zugenommen. V2X beschreibt die Fähigkeit, Daten zwischen einem Fahrzeug oder vehicle (V) und “allem” zu übertragen. In Zukunft könnten Fahrzeuge mit ihrer Umgebung kommunizieren, um Verkehrsunfälle zu vermeiden und Staus zu verringern. Dazu werden sie ihr Geschwindigkeits- und Positionsdaten über Ad-hoc-Fahrzeugnetze senden und empfangen können. Um die Verkehrssicherheit zu erhöhen, ist eine zuverlässige Kommunikationsverbindung notwendig. Die größte Herausforderung bei der Fahrzeugkommunikation besteht darin, dass sich die Eigenschaften des Physical Layers aufgrund der inhärenten Mobilität innerhalb des Kanals, der hohen Fahrzeuggeschwindigkeiten, der unterschiedlichen Antennenpositionen und der vielen Handover aufgrund kleinerer Zellen schnell ändern. Dies bringt eine Reihe von Herausforderungen in Bezug auf die Kanalcharakterisierung mit sich. Es handelt sich um einen Kanal mit starker Zeitvarianz und es treten viele Übergänge auf. Somit handelt es sich um einen nicht-stationärer (non-stationary) Kanal. Das Hauptziel dieser Untersuchung ist es, eine Methode zu finden, mit der der Kanal einer komplexen Umgebung in einer einfachen Form mit weniger strengen Beziehungen zur Geometrie dargestellt werden kann. Dabei werden die statistischen Eigenschaften ähnlich der Messdaten beibehalten. In dieser Arbeit werden nichtstationäre tapped delay line (TDL)-Modelle verwendet, um vehicle to infrastructure (V2I)-Kanäle zu beschreiben. Es wird eine neue Strategie zur Extraktion von TDL-Kanalmodellparametern aus Messdaten vorgeschlagen. Dieser Ansatz basiert auf einer bestehenden Methode zur Ableitung von Parametern für ein TDLModell. Es wird gezeigt, dass mit einer anderen Methode zur Auswahl der Taps die Anzahl der Abgriffe, die zur Rekonstruktion der root mean square delay spread (RMS-DS) eines Kanals erforderlich sind, erheblich reduziert werden kann. Ein neuer Ansatz zur überprüfen der Korrektheit der Ableitung der Kanalmodellparameter wird aufgezeigt. Die Durchführbarkeit der Methode wird anhand von Channel Sounding Messungen bestätigt. In dieser Dissertation wird ein Generator zur Erzeugung von Kanalimpulsantworten entwickelt und das nichtstationäre Verhalten der Kanäle durch die Verwendung eines ON/OFF-Prozesses beschrieben. Es werden Markov-Ketten unterschiedlicher Ordnung modelliert, um das nicht-stationäre Verhalten besser zu erfassen. Die Untersuchung zeigt, dass Markov-Ketten erster Ordnung mit zwei Zuständen vorzuziehen sind, um das häufige ON/OFF-Verhalten von Mehrwegpfaden darzustellen, und dass die Markov-Modelle zweiter und dritter Ordnung keine großen Auswirkungen haben. Eine Methode zur Erweiterung eines single input single output (SISO)-TDL-Modells auf multiple input multiple output (MIMO) unter der non-wide sense stationary uncorrelated scattering (non-WSSUS)-Annahme wird eingeführt, um TDL-Kanalmodelle für V2I MIMO-Systeme zu entwickeln. Die Analyse bewertet die SISO- mit der MIMO-Konfiguration in Bezug auf die Kanalkapazität. Es werden verschiedene MIMO-Konfigurationen untersucht, und es wird gezeigt, dass die Position der Antennen eine wichtige Rolle spielt. Die Verwendung von nur vier Antennen am transmitter (Tx) und receiver (Rx), die in unterschiedliche Richtungen abstrahlen, führt zu einem qualitativen Sprung in der Leistungsfähigkeit des Systems.In the past decades, wireless communication systems have undergone rapid development, and many investigations have been done since Maxwell predicted the existence of electromagnetic waves. In recent years, vehicle to X (V2X) communication research has been growing steadily. V2X describes the ability to transmit data between a vehicle (V) and “everything”. In the future, vehicles might be able to communicate with their environment to prevent traffic accidents and reduce congestion by allowing vehicles to transmit and receive data through a vehicular ad hoc network at their speed and position. In order to achieve the ultimate goal of enhancing transportation safety, it is crucial to establish reliable communication links. The main challenge of vehicular communications introduces new properties because the physical layer properties are rapidly changing due to inherent mobility within the channel, high vehicle speeds, varying antenna positions, and many handovers due to smaller cells. This brings up a number of challenges in terms of channel characterization because it is a strong time-variant channel and many transitions occur; therefore, it is a non-stationary channel. In this thesis, non-stationary tapped delay line (TDL) models are used to describe the vehicle to infrastructure (V2I) channels. This thesis proposes a new strategy to extract TDL channel model parameters from measurement data. The proposed approach is based on an existing method to derive parameters for a TDL model. It will be shown that with a different method of choosing taps, the number of taps necessary to regenerate the root mean square delay spread (RMS-DS) of a channel can be significantly reduced. An approach is proposed to verify the correctness of the channel model parameters derivation. The feasibility of the method will be confirmed using channel-sounding measurements. This dissertation devises a generator to produce channel impulse responses (CIRs) and describes the non-stationary behavior of the channels via employing an ON/OFF process. Different order Markov chains are modeled with the aim of better capturing the non-stationary behavior. The investigation shows that first-order two-state Markov chains are preferable to represent multipath’s frequent ON/OFF behavior, and the second- and third-order Markov models do not make enormous effects. A method for extending a single input single output (SISO)-TDL model to multiple input multiple output (MIMO) under non-wide sense stationary uncorrelated scattering (non-WSSUS) assumption is introduced to develop TDL channel models for the V2I MIMO systems. The analysis evaluates SISO- with MIMO configuration in terms of channel capacity. Different MIMO configurations are explored, and it will be illustrated that the position of antennas plays an important role. Using only four antennas at the transmitter (Tx) and receiver (Rx) that radiate towards different directions will make a qualitative leap in the performance of the system