Measurement Based Identification of MPCs in an Urban Drone-To-Drone Propagation Scenario

The risk of mid-air collisions between flying drones has to be minimized to the greatest possible extent as it endangers people in the air and on the ground especially when being integrated into dense urban airspace. For a safe and efficient operation drones will need to exchange information in a robust and reliable manner and one essential part will be direct Droneto-Drone (D2D) communications. Especially, for dense drone scenarios in urban environments a communication system must cope with the specific underlying channel propagation conditions. In order to characterize the propagation effects between two moving drones in urban environments, we performed a channel sounding measurement campaign and presented an approach in previous work to localize the origin of the measured multipath components (MPCs) for a three-dimensional layout. In this work, we apply it on our measured flight scenarios in three different environments in order to identify the MPCs by assigning them to real-world objects. Furthermore, we describe first characteristics for them and show that the measured urban scenario consists of different kinds of components that must be considered in a future D2D channel model

Two approaches for effective modelling of rain-rate time-series for radiocommunication system simulations

The paper presents a model which allows to synthetically generate rain rate time-series for a fixed location. Rain rate time-series are very much correlated with signal attenuation in Ka band and above and, thus, enable to realistically simulate propagation effects on Earth-satellite links. The model presented are based on Markov chains

Aircraft-to-Aircraft Channel Measurements in the VHF/UHF Band: Analysis of the Line-of-Sight and Lake-Reflected Channel Components

This paper presents a statistical analysis of the main components of the aircraft-to-aircraft channel based on the wideband channel measurements conducted between two aircraft in the VHF/UHF band at 250 MHz. We consider multiple flight segments where the aircraft flew at diverse altitudes and used different antennas for transmission and for reception, alternating between a top and a bottom antenna. In each scenario of interest, we analyse the power and the small-scale fading of the envelope of the direct line-of-sight component and of the specular reflection component off a lake. For both components, we compare the measured average power with the theoretical free-space path loss, and the measured small-scale fading with multiple well-known statistical distributions. The results show that the envelope of both components is strongly affected by the geometry, the location of the antennas, and by the aircraft fuselage itself. The different scenarios yield significant variations in the average power and in the distribution of the small-scale fading. A Rician distribution shows the best fit for the line-of-sight component envelope. The component reflected off the lake can be modeled by a Rician distribution when it is not obstructed or strongly affected by the aircraft fuselage, and by a Nakagami distribution otherwise. The parameters of the best-fitting distributions, including the Rician K-factor, are provided for the different scenarios

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

Analysis of the Dominant Signal Component of the Air-Ground Channel Based on Measurement Data at C-Band

Operating remotely piloted aircraft is not imaginable without a continuous data exchange between the air vehicle and the remote pilot. This data exchange requires reliable data links. One approach for such a data link discussed in the community is a terrestrial system deployed in C-band. A good knowledge of the physical conditions of the communication channel, in this case the air-ground/ground-air channel, is indispensable for the development of wireless data links. Therefore we carried out a 50MHz bandwidth channel sounding campaign with a terrestrial transmitter and an airborne receiver. In this paper we give a detailed description of our campaign setup and the processing of the collected data. The campaign covered several flight scenarios, such as take-off, taxiing, and multiple en-route maneuvers. We furthermore present results on the received power and the amplitude distribution of the first resolvable path of the received signal for the different flight scenarios. We observed significant drops in reception power during certain maneuvers that need to be considered in the design process of a data link for unmanned aviation. Additionally, we show that the amplitude distribution follows the distributions commonly used in statistical channel modeling of wireless channels to some extent. We finally present parameter sets for multiple flight scenarios for scaling the amplitude distributions to allow a statistical channel modeling of the reception power of the first resolvable signal path

Auf dem Weg zum neuen weltweiten Flugfunkstandard L-DACS

Überblick zu L-DACS1 Derzeitiger Stand der Arbeiten für den zukünftigen digitalen Flugfunkstandar

On the Potential of the European Satellite Navigation System Galileo

The contribution describes the most relevant system aspects of the European satellite navigation system Galileo focussing on signal aspects, receiver issues and application

Satellitennavigation: Einführung, Herausforderungen und Übersicht neuer Systeme

Der Vortrag behandelt das Grundprinzip der Satellitennavigation und stellt dar, aus welchen Komponenten Satellitennavigationssysteme bestehen, worin die technischen Herausforderungen dieser Systeme liegen und welche Navigationssysteme zur Zeit im Betrieb bzw. in Planung sind

Indoor Navigation

Satellitennavigationssysteme wie Galileo und GPS sind primär für den Einsatz als „Outdoor-Systeme“ vorgesehen. Um genau und verläßlich innerhalb von Gebäuden zu navigieren, müssen diese Systeme daher mit lokalen Positionierungs- und Navigationskomponenten bzw. Ergänzungssystemen wie Bewegungssensoren oder Transponder-, RFID-, WLAN und Bluetooth-Lösungen kombiniert werden. Diese Indoor-Systeme werden bereits heute in der Industrie eingesetzt, beispielsweise in der Lagerhallen-Logistik. Allerdings warten immer noch Millionen Quadratmeter Indoor-Fläche, u.a. in Parkhäusern oder für das Gebäudemanagement, auf den Einsatz dieser Technologien und bieten enormes Potential auch für Anbieter und Anwender aus kleinen und mittelständischen Unternehmen. Die eingesetzten Technologien müssen den Ansprüchen einer „seamless navigation“ mit nahtlosem Übergang zwischen den verschiedenen Systemen erfüllen, d.h. der Nutzer darf nicht bemerken, welches Indoor- und Outdoor-Navigationssystem er gerade verwendet. Der Vortrag gibt einen Überblick über den State-of-the-Art in Forschung und Entwicklung und stellt neue Technologien und Verfahren vor, die das DLR entwickelt

Strengthening the Satellite Navigation Community on Bavarian, German and European Level

The contribution presents the key system aspects of the European satellite navigation system Galileo and highlights the potential for new application