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PalCom is a middleware toolkit for pervasive computing and internet-of-things. We discuss how PalCom supports exploration and live programming through three phases: exploring services, assembling them into applications, and exposing them as new services. We give an example of this workflow through the construction of a simple photo booth application.
We investigate the ability of Massive multiple-input multiple-output (MIMO) systems to spatially separate up to eighteen users located close to one another in line-of-sight (LOS) propagation conditions, in both indoor and outdoor environments. For that, we use fully-synchronous measured channels at 2.6 GHz of single-antenna users moving within a small area and concurrently communicating with a bas
Massive multiple-input multiple-output (MIMO) has gained a tremendous amount of attention as a key enabler of fifth-generation cellular systems. The majority of the vast literature on massive MIMO is based on fully digital processing, where each antenna element in the massive array is equipped with an up/down-conversion chain. Unlike previous works, we present a suite of greedy algorithms using pu
Favorable propagation (FP) and channel hardening (CH) are desired properties in massive multiple-input multiple-output (MIMO) systems. To date, these properties have primarily been analyzed for classical statistical channel models, or ray-based models with very specific angular parameters and distributions. This paper presents a thorough mathematical analysis of the asymptotic system behavior for
A low-cost microstrip patch antenna array is proposed in this paper for automotive radar applications in ISM 24 GHz band. The elements of the center-fed array are connected in series to make a compact design with low complexity by obviating Wilkinson power divider. This approach also helps to reduce the dielectric losses of the array. A full-wave electromagnetics (EM) software EMPIRE XPU is used i
In an increasingly connected world where all manner of devices can communicate over the Internet, conventional methods for developing GUIs (Graphical User Interfaces) are insufficient. For systems of such devices, it must be possible to develop the system itself independently from its GUI(s). In this paper, we present an approach for developing GUIs towards already deployed, or "live", service-bas
We present and analyze a new approach to improve energy efficiency in cellular IoT devices. The new approach consists of employment of ultra low power wake-up receivers in combination with robust non-coherent modulation. The results show that we can achieve very competitive power consumption, reducing it by up to 50 times, compared to two conventional power saving solutions we use as references. T
We envision the use of large intelligent surface (LIS) technology, which is a promising concept that goes beyond massive multiple-input multiple-output (MIMO), for positioning applications due to its ability to focus energy in the 3D space. The Cramér-Rao lower bounds (CBLBs) for positioning using a LIS which can resolve amplitude and phase with full resolution have already been determined in the
We present a new type of wireless access infrastructure consisting of a fabric of dispersed electronic circuits and antennas that collectively function as a massive, distributed antenna array. We have chosen to name this new wireless infrastructure 'RadioWeaves' and anticipate they can be integrated into indoor and outdoor walls, furniture, and other objects, rendering them a natural part of the e
This paper proposes a pragmatic methodology to characterize mutual coupling in uniform linear arrays (ULAs). The classical coupling model used in the literature of multiple input multiple output (MIMO) antenna arrays is based on impedance parameters, resulting valid only for electromagnetically small antennas, e.g. short dipole. To test the robustness and accuracy of the proposed coupling model we
Internet-of-things systems are difficult to understand and debug due to their distributed nature and weak connectivity. We address this problem by using relational reference attribute grammars to model and analyze IoT systems with unreachable parts. A transitive device-dependency analysis is given as an example.
In ubiquitous computing, end-user composition allows users to combine multiple single-purpose devices into new, interesting constellations. In PalCom – a ubiquitous middleware – this is achieved without the need to write program code. In this paper we present a solution that in the same way allows users to create Graphical User Interfaces (GUIs) for such systems without coding. The approach is to
Reliable connectivity between vehicles is a requirement for efficient overtaking warning systems. We investigate the 6 GHz propagation channel between oncoming vehicles with five different types of large obstructing vehicles in a poor scattering environment. The presented channel gains emphasize the advantages of different antenna positions and the difference between a straight road and curved roa
Algorithms for secure encryption in a post-quantum world are currently receiving a lot of attention in the research community, including several larger projects and a standardization effort from NIST. One of the most promising algorithms is the code-based scheme called QC-MDPC, which has excellent performance and a small public key size. In this work we present a very efficient key recovery attack
This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in
One of the basic aspects of Massive MIMO (MaMi) that is in the focus of current investigations is its potential of using low-cost and energy-efficient hardware. It is often claimed that MaMi will allow for using analog-to-digital converters(ADCs) with very low resolutions and that this will result in overall improvement of energy efficiency. In this contribution, we perform a parametric energy eff
Multi-atlas segmentation has become a frequently used tool for medical image segmentation due to its outstanding performance. A computational bottleneck is that all atlas images need to be registered to a new target image. In this paper, we propose an intermediate representation of the whole atlas set – an überatlas – that can be used to speed up the registration process. The representation consis
Two different solutions for the characteristic modes (CMs) of lossy structures were previously developed using induced volume currents. The first solution diagonalizes the scattering and perturbation matrices, guaranteeing far-field orthogonality at the cost of imaginary eigenvalues and eigencurrents. The second solution does not perfectly diagonalize these matrices, but maintains real-valued eige
