Kaiserslautern - Fachbereich Elektrotechnik und Informationstechnik
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The number of sensors used in modern devices is rapidly increasing, and the interaction with sensors demands analog-to-digital data conversion (ADC). A conventional ADC in leading-edge technologies faces
many issues due to signal swings, manufacturing deviations, noise, etc. Designers of ADCs are moving to the
time domain and digital designs techniques to deal with these issues. This work pursues a novel self-adaptive
spiking neural ADC (SN-ADC) design with promising features, e.g., technology scaling issues, low-voltage
operation, low power, and noise-robust conditioning. The SN-ADC uses spike time to carry the information.
Therefore, it can be effectively translated to aggressive new technologies to implement reliable advanced sensory electronic systems. The SN-ADC supports self-x (self-calibration, self-optimization, and self-healing) and
machine learning required for the internet of things (IoT) and Industry 4.0. We have designed the main part of
SN-ADC, which is an adaptive spike-to-digital converter (ASDC). The ASDC is based on a self-adaptive complementary metal–oxide–semiconductor (CMOS) memristor. It mimics the functionality of biological synapses,
long-term plasticity, and short-term plasticity. The key advantage of our design is the entirely local unsupervised
adaptation scheme. The adaptation scheme consists of two hierarchical layers; the first layer is self-adapted, and
the second layer is manually treated in this work. In our previous work, the adaptation process is based on 96 variables. Therefore, it requires considerable adaptation time to correct the synapses’ weight. This paper proposes a
novel self-adaptive scheme to reduce the number of variables to only four and has better adaptation capability
with less delay time than our previous implementation. The maximum adaptation times of our previous work
and this work are 15 h and 27 min vs. 1 min and 47.3 s. The current winner-take-all (WTA) circuits have issues, a
high-cost design, and no identifying the close spikes. Therefore, a novel WTA circuit with memory is proposed.
It used 352 transistors for 16 inputs and can process spikes with a minimum time difference of 3 ns. The ASDC
has been tested under static and dynamic variations. The nominal values of the SN-ADC parameters’ number
of missing codes (NOMCs), integral non-linearity (INL), and differential non-linearity (DNL) are no missing
code, 0.4 and 0.22 LSB, respectively, where LSB stands for the least significant bit. However, these values are
degraded due to the dynamic and static deviation with maximum simulated change equal to 0.88 and 4 LSB and
6 codes for DNL, INL, and NOMC, respectively. The adaptation resets the SN-ADC parameters to the nominal
values. The proposed ASDC is designed using X-FAB 0.35 µm CMOS technology and Cadence tools.
Sensing location information in indoor scenes requires a high accuracy and is a challenging task, mainly because of multipath and NLoS (non-line-of-sight) propagation. GNSS signals cannot penetrate well in indoor environment. Satellite-based navigation and positioning systems cannot therefore be used for indoor positioning.. Other technologies have been suggested for indoor usage, among them, Wi-Fi (802.11) and 5G NR (New Radio). The primary aim of this study is to discuss the advantages and drawbacks of 5G and Wi-Fi positioning techniques for indoor localization.
In search of new technologies for optimizing the performance and space requirements of electronic and optical micro-circuits, the concept of spoof surface plasmon polaritons (SSPPs) has come to the fore of research in recent years. Due to the ability of SSPPs to confine and guide the energy of electromagnetic waves in a subwavelength space below the diffraction limit, SSPPs deliver all the tools to implement integrated circuits with a high integration rate. However, in order to guide SSPPs in the terahertz frequency range, it is necessary to carefully design metasurfaces that allow one to manipulate the spatio-temporal and spectral properties of the SSPPs at will. Here, we propose a specifically designed cut-wire metasurface that sustains strongly confined SSPP modes at terahertz frequencies. As we show by numerical simulations and also prove in experimental measurements, the proposed metasurface can tightly guide SSPPs on straight and curved pathways while maintaining their subwavelength field confinement perpendicular to the surface. Furthermore, we investigate the dependence of the spatio-temporal and spectral properties of the SSPP modes on the width of the metasurface lanes that can be composed of one, two or three cut-wires in the transverse direction. Our investigations deliver new insights into downsizing effects of guiding structures for SSPPs.
Modern applications in the realms of wireless communication and mobile broadband Internet increase the demand for compact antennas with well defined directivity. Here, we present an approach for the design and implementation of hybrid antennas consisting of a classic feeding antenna that is near-field-coupled to a subwavelength resonator. In such a combined structure, the composite antenna always radiates at the resonance frequency of the subwavelength oscillator as well as at the resonance frequency of the feeding antenna. While the classic antenna serves as impedance-matched feeding element, the subwavelength resonator induces an additional resonance to the composite antenna. In general, these near-field coupled structures are known for decades and are lately published as near-field resonant parasitic antennas. We describe an antenna design consisting of a high-frequency electric dipole antenna at fd=25 GHz that couples to a low-frequency subwavelength split-ring resonator, which emits electromagnetic waves at fSRR=10.41 GHz. The radiating part of the antenna has a size of approximately 3.2mm×8mm×1mm and thus is electrically small at this frequency with a product k⋅a=0.5 . The input return loss of the antenna was moderate at −18 dB and it radiated at a spectral bandwidth of 120 MHz. The measured main lobe of the antenna was observed at 60∘ with a −3 dB angular width of 65∘ in the E-plane and at 130∘ with a −3 dB angular width of 145∘ in the H-plane
Die fortschreitende Verbreitung von Ethernet-basierten Strukturen mit dezentralen und verteilten Anwendungen in der Automatisierung führt zu den so genannten netzbasier-ten Automatisierungssystemen (NAS). Diese sind zwar in Anschaffung und Betrieb kostengünstiger, moderner und flexibler als herkömmliche Strukturen, weisen jedoch nicht-deterministische Verzögerungen auf. Die genaue Analyse der resultierenden Antwortzeiten ist somit nicht nur Voraussetzung für den verantwortungsbewussten Einsatz dieser Technologie sondern ermöglicht es auch, bereits im Vorfeld von Umstrukturierungen oder Erweiterungen, Fragen der Verlässlichkeit zu klären. In diesem ersten von zwei Beiträgen wird hierfür zunächst die für die speziellen Bedürfnisse der Strukturbeschreibung von netzbasierten Automatisierungssystemen entwickelte Modellierungssprache DesLaNAS vorgestellt und auf ein einführendes Beispiel angewendet. Im zweiten Beitrag wird darauf aufbauend gezeigt, welchen Einfluss die einzelnen System-komponenten (SPS, Netzwerk, I/O-Karten) sowie netzbedingte Verhaltensmodi wie Synchronisation und die gemeinsame Nutzung von Ressourcen auf die Antwortzeiten des Gesamtsystems haben. Zur Analyse selbst wird die wahrscheinlichkeitsbasierte Modellverifikation (PMC) angewendet.
Netzbasierte Automatisierungssysteme (NAS) sind das Ergebnis der zunehmenden Dezentralisierung von Automatisierungssystemen mittels neuerer Netzwerkstrukturen. Eine ganze Fülle von Einflussfaktoren führt jedoch zu einem Spektrum von nicht-deterministischen Verzögerungen, die direkten Einfluss auf Qualität, Sicherheit und Zuverlässigkeit der Automatisierungsanlagen haben. Eine genaue Analyse dieser Einflussfaktoren ist somit nicht nur Voraussetzung für den verantwortungsbewussten Einsatz dieser Technologie sondern ermöglicht es auch, bereits im Vorfeld von Umstrukturierungen oder Erweiterungen Fragen der Verlässlichkeit zu klären. In diesem Beitrag wird gezeigt, welchen Einfluss einzelne Komponenten sowie netzbedingte Verhaltensmodi wie Synchronisation und die gemeinsame Nutzung von Ressourcen auf die Antwortzeiten des Gesamtsystems haben. Zur Analyse wird die wahrscheinlichkeitsbasierte Modellverifikation (PMC) verwendet. Umfangreiche Messungen wurden zur Validierung der Ergebnisse durchgeführt.
The mapping of a virtual network service onto a physical network infrastructure is a challenging task due to the joint allocation of virtual resources across nodes and links, the diverse technical requirements of end-users, the coordination between multiple host domains, and others. This issue is exacerbated further by the extension of virtualization to the next-generation radio access network (NG-RAN) architecture and the provisioning of radio access network (RAN) slicing. To that end, this article focuses on the mapping problem of the virtual network functions (VNFs), as well as their internal and external virtual links (VLs), of a RAN slice subnet onto intelligent points of presence (I-PoPs) and transport networks in the NG-RAN architecture. In this context, in contrast to the majority of the state-of-the-art proposals, which frequently fail to achieve performance objectives and neglect resource allocation constraints, this article introduces automation and intelligence at an architectural level to map VNFs and VLs onto their corresponding physical nodes and links, with the goal of achieving superior efficiency in virtual resource utilization while granting the performance of a RAN slice subnet. Benefiting from a top-down approach, the key contributions of this article are: (i) to extend the architectural framework of network slicing towards the NG-RAN architecture and provide a comprehensive overview and critical analysis of the components and functionalities of a RAN slice subnet; (ii) to integrate the Experiential Network Intelligence (ENI) framework into a joint architecture of the network functions virtualization–management and orchestration (NFV–MANO), Third Generation Partnership Project-network slicing management system (3GPP-NSMS), and I-PoPs in order to render automation and intelligence to the management and orchestration aspects of a RAN slice subnet in the NG-RAN architecture; and (iii) to propose a learning-assisted architectural solution for mapping the VNFs, as well as their internal and external VLs, of a RAN slice subnet onto the underlying I-PoPs and transport networks.
The fifth-generation mobile telecommunication network is expected to support multi-access edge computing (MEC), which intends to distribute computation tasks and services from the central cloud to the edge clouds. Toward ultra-responsive, ultra-reliable, and ultra-low-latency MEC services, the current mobile network security architecture should enable a more decentralized approach for authentication and authorization processes. This paper proposes a novel decentralized authentication architecture that supports flexible and low-cost local authentication with the awareness of context information of network elements such as user equipment and virtual network functions. Based on a Markov model for backhaul link quality as well as a random walk mobility model with mixed mobility classes and traffic scenarios, numerical simulations have demonstrated that the proposed approach is able to achieve a flexible balance between the network operating cost and the MEC reliability.
Radar cross section reducing (RCSR) metasurfaces or coding metasurfaces were primarily designed for normally incident radiation in the past. It is evident that the performance of coding metasurfaces for RCSR can be significantly improved by additional backscattering reduction of obliquely incident radiation, which requires a valid analytic conception tool. Here, we derive an analytic current density distribution model for the calculation of the backscatter far-field of obliquely incident radiation on a coding metasurface for RCSR. For demonstration, we devise and fabricate a metasurface for a working frequency of 10.66GHz and obtain good agreement between the measured, simulated, and analytically calculated backscatter far-fields. The metasurface significantly reduces backscattering for incidence angles between −40∘ and 40∘ in a spectral working range of approximately 1GHz.
Modern society relies on convenience services and mobile communication. Cloud computing is the current trend to make data and applications available at any time on every device. Data centers concentrate computation and storage at central locations, while they claim themselves green due to their optimized maintenance and increased energy efficiency. The key enabler for this evolution is the microelectronics industry. The trend to power efficient mobile devices has forced this industry to change its design dogma to: ”keep data locally and reduce data communication whenever possible”. Therefore we ask: is cloud computing repeating the aberrations of its enabling industry?