Effect of Non-Integer Delay on Ranging Accuracy for Ultra-Reliable Systems

Ultra-reliable communication systems are drawing a lot of attention due to the rising demand on new wireless technologies for safety critical applications. Many of these applications require ultra-reliable distance estimation between the communicating nodes. Automatic coupling between train wagons is one of the scenarios where ultra-reliable communication and ranging at short distances is required. The main objective of this paper is to define a theoretical channel model for the aforementioned scenario, to define a proper discrete equivalence of the communication system model, to derive Cram´er Rao Lower Bounds for ranging accuracy. Ranging accuracy simulation results are provided using three systems: ITS-G5, IR-UWB, and a proposed 5G wide band system operating in the mm-Wave frequency band. We show from the results that the proposed mm-Wave system is suitable for ultra-reliable ranging at short distances

Vehicular-to-Pedestrian Channel Models

Protect vulnerable road users with reliable vehicle-to-pedestrian (V2P) communications to reduce accidents Accurate V2P channel models to design reliable V2P communications Comparison of vehicle-to/everything (V2X) channels Related work on V2P channel models V2P path loss model

Geometric Analysis of the Doppler Frequency for General Non-Stationary 3D Mobile-to-Mobile Channels based on Prolate Spheroidal Coordinates

Mobile-to-mobile channels often exhibit timevariant Doppler frequency shifts due to the movement of transmitter and receiver. An accurate description of the Doppler frequency turns out to be very difficult in Cartesian coordinates, and any subsequent algebraic analysis of the Doppler frequency is intractable. In contrast to other approaches, we base our investigation on a geometric description of the Doppler frequency with the following three mathematical pillars: prolate spheroidal coordinate system, algebraic curve theory, and differential forms. The prolate spheroidal coordinate system is more appropriate to algebraically investigate the problem. After the transformation into the new coordinate system, the theory of algebraic curves is needed to resolve the ambiguities. Finally, the differential forms are required to derive the joint delay Doppler probability density function. This function is normalized by the equivalent ellipsoidal area of the scattering plane bounded by the delay ellipsoid. The results generalize in a natural way our previous model to a complete 3D description. Our solutions enable insight into the geometry of the Doppler frequency and we were able to derive a Doppler frequency that is dependent on the delay and the scattering plane. The presented theory allows describing any time-variant, single-bounce, mobile-to-mobile scattering channel

Bayesian multipath-enhanced device-free localization: Simulation- and measurement-based evaluation

Device-free localisation (DFL) systems infer presence and location of moving users by measuring to which extent they change the received signal power in wireless links. Consequently, users not only induce perturbations to the power of the line of sight but also to the power of reflected and scattered signals which are observed in the received signal as multipath components (MPCs). Since the propagation paths of MPCs differ inherently from the line-of-sight path, these propagation paths can be considered as additional network links. This extended network determines the multipath-enhanced device-free localisation (MDFL) system. Based on empirical models that relate perturbations in the received power of MPCs to the user location, the localisation problem can be solved by non-linear Bayesian filtering. In this work, we investigate the point mass filter and the particle filter as possible solutions. We demonstrate the applicability of these solutions using ultra-wideband measurements and develop and verify a numerical simulation framework that flexibly enables a sound evaluation of MDFL. Based on both measurements and simulations, we show a significant improvement of the localisation performance of MDFL compared to DFL. The overall localisation performance is thereby comparable for both filters. Eventually, we show that complexity and divergence probability, rather than localisation performance, are the decisive factors for the choice of the filter solution

Geometric Analysis of the Doppler Frequency for General Non-stationary 3D Mobile-to-Mobile Channels Based on Prolate Spheroidal Coordinates

—Mobile-to-mobile channels often exhibit time-variant Doppler frequency shifts due to the movement of transmitter and receiver. An accurate description of the Doppler frequency turns out to be very difficult in Cartesian coordinates and any subsequent algebraic analysis of the Doppler frequency is intractable. In contrast to other approaches, we base our investigation on a geometric description of the Doppler frequency with the following three mathematical pillars: prolate spheroidal coordinate system, algebraic curve theory, and differential forms. The prolate spheroidal coordinate system is more appropriate to algebraically investigate the problem. After the transformation into the new coordinate system, the theory of algebraic curves is needed to resolve the ambiguities. Finally, the differential forms are required to derive the joint delay Doppler probability density function. This function is normalized by the equivalent ellipsoidal area of the scattering plane bounded by the delay ellipsoid. The results generalize in a natural way our previous model to a complete 3D description. Our solutions enable insight into the geometry of the Doppler frequency and we were able to derive a Doppler frequency that is dependent on the delay and the scattering plane. The presented theory allows describing any time-variant, single-bounce, mobile-to-mobile scattering channel

Risk governance in organizations

Dieses Buch dokumentiert 10 Jahre Risk-Governance-Forschung an der Universität Siegen. In 50 Beiträgen reflektieren Forscher und Praktiker Risk Governance vor dem Hintergrund ihrer eigenen Forschungen und/oder Erfahrungen und geben jeweils einen Entwicklungsimpuls für die Zukunft der Risk Governance. Das Buch zeigt die große Bandbreite und Tiefe des Forschungsgebietes auf und diskutiert Grundannahmen, Implementierungsfragen, die Rolle der Risk Governance als Transformationsmotor, ihre Wirkung in den verschiedenen betrieblichen Funktionen, Entwicklungsperspektiven und den Beitrag der Risk Governance zu einer nachhaltigen Ausrichtung von Unternehmen.This book documents 10 years of risk governance research at the University of Siegen. In 50 contributions, researchers and practitioners reflect on risk governance against the background of their own research and/or experience and provide a development impetus for the future of risk governance. The book shows the wide range and depth of the research field and discusses basic assumptions, implementation issues, the role of risk governance as transformation engine, its impact in the various operational functions, development perspectives, and the contribution of risk governance to a sustainable orientation of companies

Ubiquitous Radio Sensing: Localization of Non-Cooperative Users

Many applications in the emerging smart environments, such as smart cities and intelligent transportation, require an accurate situational awareness, i.e., information about presence and location of all users in the environment. For example, situational awareness enables location-aware home control, assistive health, or vehicular safety applications. A reliable situational awareness is based on robust communications and sensing techniques, as well as large-scale deployment with respect to the application environment. This demand for both communications and sensing capabilities has recently led to significant research interests in merging the two technologies allowing for an efficient use of spectral resources and a beneficial mutual assistance. An integration of sensing functionality is envisioned as a native capability of next generation wireless networks. The deployment of these perceptive wireless networks ultimately offers the prospect of ubiquitous radio sensing. Ubiquitous radio sensing allows, in particular, the localization of non-cooperative users. In this context, non-cooperative users are defined as users who are neither equipped with a communications device nor with a dedicated localization device. State-of-the-art algorithms on localizing non-cooperative users typically obtain the required location information exclusively from directly scattered or reflected signals. Further signal components resulting from multipath propagation, for example due to reflections from the surrounding environment, are considered as interfering signals, i.e., clutter, and are suppressed by the receiver. In this thesis, we propose to exploit the full potential of signal propagation, including multipath, for the localization of non-cooperative users. Therefore, we first provide detailed insights into time-based radio sensing. We derive, develop, and implement the fundamental performance bounds, clutter mitigation techniques, as well as parameter estimation and tracking algorithms to localize non-cooperative users. Moreover, we provide a novel radio sensing approach, referred to as multipath-enhanced device-free localization (MDFL), which complements time-based radio sensing. Instead of mitigating signal components, MDFL makes use of the spatial information contained in the corresponding propagation paths to localize non-cooperative users. For localization, MDFL exploits user-induced variations in the received power of the individual signal components. These signal components include besides the line-of-sight also multipath components. For realizing this novel sensing approach, we develop corresponding measurement models relating the user-induced variations in the received power of the individual signal components to the user’s location. Based on these measurement models, we derive the fundamental performance bounds for MDFL. Finally, we present a Bayesian formulation of the sensing problem and implement corresponding non-parametric filter solutions for MDFL, which are successfully applied to measurement data. To the best of the author’s knowledge, this is the first time it is shown that variations in the power of multipath components can be used for the localization of non-cooperative users. Due to its low computational complexity, the proposed MDFL approach represents a suitable technique for the emerging perceptive wireless networks and can help to enable ubiquitous radio sensing

Ranging and multipath-enhanced device-free localisation with densely-meshed ultra-wideband devices

Device-free localisation (DFL) is a prominent example of radio sensing and radio frequency (RF)-based passive localisation. RF-based passive localisation approaches determine the position of a non-cooperative user based on the user's impact on radio propagation. In this regard, DFL systems measure user-induced changes in the properties of the received RF signals. With multipath-enhanced device-free localisation (MDFL), a novel passive localisation approach which is taking the advantage of user-induced fading in the multipath signals, that is, reflected and scattered signals is introduced. In this work, the authors realise an MDFL system using low-cost ultra-wideband (UWB) devices. Specifically, the Qorvo (DecaWave) DW1000 module is used, for which how to access the channel impulse response is described in detail. Additionally, an overview of the required signal processing for MDFL is provided and a possible sequential Bayesian approach is introduced. Moreover, an efficient ranging scheme based on time-division multiple access (TDMA) and message broadcasting is outlined, which allows the deployment of a large number of interconnected UWB devices. Using an exemplary network of interconnected UWB devices, the localisation performance of both DFL and MDFL for an indoor scenario is evaluated. Thereby, MDFL is shown to clearly outperform DFL in terms of robustness and accuracy. Furthermore, a TDMA-based ranging scheme for active localisation is used, that is, for localising an UWB device carried by the user, allowing for a direct comparison between active and passive localisation. Achieving a sub-decimetre accuracy, the active localisation outperforms both DFL and MDFL, and thus, shows the possibility of using an active localisation device to initialize MDFL

Multipath-enhanced device-free localization using low-cost ultra-wideband devices

Multipath propagation can improve device-free lo-calization (DFL). In this work, we therefore provide an overview of the required signal processing for multipath-enhanced device-free localization (MDFL) and introduce a possible sequential Bayesian approach. Furthermore, we demonstrate that low-cost ultra-wideband devices can be used for MDFL. Specifically, we use the Qorvo (DecaWave) DWM1000 module, for which we describe how to access the channel impulse response in detail. Based on a sparse network of ultra-wideband devices, we evaluate the localization performance of both DFL and MDFL for an indoor scenario. Thereby, MDFL is shown to clearly outperform DFL in terms of localization performance