Refine
Departments, institutes and facilities
Document Type
- Conference Object (50)
- Article (7)
- Part of a Book (1)
- Doctoral Thesis (1)
- Patent (1)
- Report (1)
Year of publication
Keywords
- WiLD (3)
- 802.11 (2)
- IEEE 802.11 (2)
- IEEE802.11 (2)
- Internet (2)
- LoRa (2)
- Long-Distance WiFi (2)
- OpenFlow (2)
- WiFi (2)
- Customization (1)
- Directional Antenna (1)
- Directional antennas (1)
- EnOcean (1)
- FS20 (1)
- Forschungsprojekt (1)
- Free-Space Loss (FSL) (1)
- HomeMatic (1)
- IEEE 802.11n (1)
- IEEE 802.21 (1)
- Interference (1)
- KNX (1)
- Kommunikationsvernetzung (1)
- LAA (1)
- LTE-U (1)
- LoRa receiver accuracy (1)
- LoRaWAN (1)
- Long-distance (1)
- Longley-Rice (1)
- Longley-Rice Irregular Terrain Model (ITM) (1)
- MAC (1)
- MIMO (1)
- MPLS (1)
- Measurement (1)
- Multicast communication (1)
- Norm (1)
- Open source firmware (1)
- Paketvermittlung (1)
- Path loss model (1)
- Propagation (1)
- QoS (1)
- Qualitäts-Service (1)
- RSSI (1)
- Router (Rechnernetz) (1)
- SDN (1)
- SDWN (1)
- Scalability (1)
- Security (1)
- Simulation (1)
- Spectrum occupancy (1)
- TLS (1)
- Telecommunication network reliability (1)
- Telecommunication network routing (1)
- Token (1)
- Two-Ray (1)
- U-NII band (1)
- WDS (1)
- Weitverkehrsnetz (1)
- Wi-Fi (1)
- WiAFirm (1)
- WiFi-based Long Distance (WiLD) (1)
- Wireless Backhaul Network (1)
- Wireless back-haul (1)
- Wireless backhaul (1)
- ZWave (1)
- ZigBee (1)
- bootstrapping (1)
- building automation (1)
- cognitive radio (1)
- directional antennas (1)
- einheitliches Internet-Übertragungsprotokoll (1)
- interference (1)
- link calibration (1)
- lokales Netz (1)
- long-distance 802.11 (1)
- routing (1)
- rural areas (1)
- security (1)
- self-configuration (1)
- self-management (1)
- software-defined networking (1)
- spectrum scan (1)
- spectrum sensing (1)
- verteiltes System (1)
- wireless mesh networks (1)
- wmSDN (1)
- Übertragungsqualität (1)
Quantifying Interference in WiLD Networks using Topography Data and Realistic Antenna Patterns
(2019)
Avoiding possible interference is a key aspect to maximize the performance in Wi-Fi based Long Distance networks. In this paper we quantify self-induced interference based on data derived from our testbed and match the findings against simulations. By enhancing current simulation models with two key elements we significantly reduce the deviation between testbed and simulation: the usage of detailed antenna patterns compared to the cone model and propagation modeling enhanced by license-free topography data. Based on the gathered data we discuss several possible optimization approaches such as physical separation of local radios, tuning the sensitivity of the transmitter and using centralized compared to distributed channel assignment algorithms. While our testbed is based on 5 GHz Wi-Fi, we briefly discuss the possible impact of our results to other frequency bands.
Quantifying the spectrum occupancy in an outdoor 5 GHz WiFi network with directional antennas
(2018)
WiFi-based Long Distance networks are seen as a promising alternative for bringing broadband connectivity to rural areas. A key factor for the profitability of these networks is using license free bands. This work quantifies the current spectrum occupancy in our testbed, which covers rural and urban areas alike. The data mining is conducted on the same WiFi card and in parallel with an operational network. The presented evaluations reveal tendencies for various aspects: occupancy compared to population density, occupancy fluctuations, (joint)-vacant channels, the mean channel vacant duration, different approaches to model/forecast occupancy, and correlations among related interfaces.
Real-World Performance of current Mesh Protocols in a small-scale Dual-Radio Multi-Link Environment
(2017)
Two key questions motivated the work in this paper: What is the impact of different usage schemes for multiple channels in a dual-radio Wireless Mesh Network (WMN), and what is the impact of some popular WMN routing protocols on its performance. These two questions were evaluated in a small and simple real-world scenario. A major concern was reproducibility of the results. We show that it is beneficial to use both radios on different frequencies in a fully meshed environment with four routers. The routing protocols Babel, B.A.T.M.A.N. V, BMX7 and OLSRv2 recognize a saturated channel and prefer the other one. We show that in our scenario all of the protocols perform equally well since the protocol overhead is comparably low not influencing the overall performance of the network.
Reliable multicast transport services for content delivery in heterogeneous mobile environment
(2007)
For efficient deployment of new reliable multicast applications in heterogeneous mobile Internet environments, appropriate retransmission strategies are proposed. The focus is the minimization of the protocol overhead for reliable transport taking into account behaviour in mobile networks (oss and handover behaviour) and application requirements (such as carousel file transfer, one-to-many download and media streaming combined with recording). The proposed techniques are designed as building blocks for localized multicast error control supported by access routers. Considering IETF RMT standardization work, the discussed retransmission approaches can be used for flexible configuration of tree-based reliable multicast protocols in converged wired and wireless Internet environment. The implementation developed for the European project DAIDALOS [1] is based on Linux IPv6 environment. Simulations in ns2 focusing on the benefits of the proposed multicast retransmission schemes for particular application scenarios are presented.
This paper describes the security mechanisms of several wireless building automation technologies, namely ZigBee, EnOcean, ZWave, KNX, FS20, and Home-Matic. It is shown that none of the technologies provides the necessary measure ofsecurity that should be expected in building automation systems. One of the conclusions drawn is that software embedded in systems that are build for a lifetime of twenty years or more needs to be updatable.
Zukünftige Netze sollen in der Lage sein, eine Vielzahl verschiedener Dienste zu unterstützen. Dabei wird angenommen, dass sie oft keine statische Netzwerkstruktur haben und sich daher selbsttätig konfigurieren und automatisch an wechselnde Anforderungen sowie Netzwerksituationen und -änderungen anpassen sollen. Es ist wünschenswert, dass die benötigte Dienstqualität (QoS), im Besonderen für zeitkritische Anwendungen wie VoIP, automatisch gewährleistet werden kann. Das Netz soll zukünftigen Anforderungen gerecht werden, auch wenn diese zum Zeitpunkt der Erstellung noch nicht relevant oder bekannt sind. In diesem Dokument wird ein möglicher Ansatz des noch jungen Forschungsprojekts Self-NET für die Erfüllung der genannten Anforderungen skizziert und zur Diskussion gestellt.
Verschiedene intelligente Heimautomatisierungsgeräte wie Lampen, Schlösser und Thermostate verbreiten sich rasant im privaten Umfeld. Ein typisches Kommunikationsprotokoll für diese Geräteklasse ist Bluetooth Low Energy (BLE). In dieser Arbeit wird eine strukturierte Sicherheitsanalyse für BLE vorgestellt. Die beschriebene Vorgehensweise kategorisiert bekannte Angriffsvektoren und beschreibt einen möglichen Aufbau für eine Analyse. Im Zuge dieser Arbeit wurden einige sicherheitsrelevante Probleme aufgedeckt, die es Angreifern ermöglichen die Geräte vollständig zu übernehmen. Es zeigte sich, dass im Standard vorgesehene Sicherheitsfunktionen wie Verschlüsselung und Integritätsprüfungen häufig gar nicht oder fehlerhaft implementiert sind.