Jirka Klaue

A Survey of Low-Power Transceivers and Their Applications

In wireless sensor networks (WSNs) energy efficiency and communication reliability are often conflicting requirements. Additionally, some application areas such as industrial automation or infrastructure monitoring impose strict latency bounds. Low-power receivers (<; 1 mW power consumption) together with adapted MAC protocols have the potential to meet these diverse requirements. We present an overview of state-of-the-art low-power receivers and relate their characteristics to requirements for different application areas. We compare low-power receivers to duty-cycled transceivers and present applications depending on them. For this, we use power consumption, sensitivity, and data rate as key performance figures for low-power receivers. Based on the characteristics of the applications we derive guidelines for using low-power receivers instead of duty-cycled transceivers.

Error characterization of multi-access point WSNs in an aircraft cabin

We present the packet error rate (PER) characterization of an aircraft cabin wireless sensor network (WSN). It is based on measurements for a static and a typical dynamic environment, which were both performed in an aircraft cabin mockup. The WSN exploits spatial diversity by using multiple access points, which decreases the average PER by several orders of magnitude. The characterization gives the individual and combined PER, burst error and run length distributions as well as bit error rates for packets which were received, but with errors. The exploitation of spatial redundancy eliminates the additional packet losses caused by the presence of people in the environment.

RedFixHop: Efficient Ultra-Low-Latency Network Flooding

A Constructive Interference-based flooding mechanism - using hardware-generated ACKs - is proposed to achieve highly reliable source-to-sink communication of very short critical packets in a wireless sensor network working in harsh environments. Constructive interference is only achieved if the senders synchronize their packet transmissions with sub-microsecond accuracy. In order to achieve the required synchronization accuracy, the packet retransmissions at the relay nodes are triggered by using hardware acknowledgements.

In-cabin localization solution for optimizing manufacturing an d maintenance proces ses for civil aircrafts

This indoor localization solution enables optimization of manufacturing and maintenance processes of civil aircrafts. The use cases include localization of fixed entities like life vests, passenger service units, and seats and mobile entities like flight attendance panels and devices of maintenance workers. Following these use cases, the solution approach features the combination of fingerprinting approaches using Support Vector Machines and distance-based approaches like Trilateration and Weighted Centroid. The proposal has been intensively studied in an Airbus A340 cabin mock-up model by measurement campaigns with a real system deployment.

Experiments with UWB aircraft sensor networks

We present an ultra-wideband (UWB) sensor network, deployed for aircraft applications. Off-the-shelf IEEE 802.15.4-2011 UWB compliant transceivers are, so far, only used for localization purposes. Thus, we modify transceiver configurations to enable data communication and realize a time division MAC scheme. Shadowing and the impact of passenger mobility are experimentally evaluated. Furthermore, channel attenuation and small-scale fading is analyzed, considering empty and occupied cabin cases and different node deployment positions.

RedFixHop with channel hopping: Reliable ultra-low-latency network flooding

A constructive interference (CI) based flooding mechanism, using hardware-generated acknowledgments (ACKs), is proposed to achieve highly reliable source-to-sink communication of very short critical packets within a wireless sensor network (WSN) working in harsh environments. CI is only achieved if the senders synchronize their packet transmissions with sub-microsecond precision. In order to achieve the required synchronization accuracy, the packet retransmissions at the relay nodes are triggered by using hardware ACKs. To further increase packet reception probability, channel diversity is exploited using a predefined hopping sequence. The protocol performance is experimentally evaluated by implementing it using IEEE 802.15.4 radio transceivers.

Reliable real-time wireless sensor networks using spatial diversity

Wireless sensor networks for aerospace applications need to provide reliable communications with guaranteed real-time functionality in order to serve the requirements of especially the flight control domain. Additionally, the communication system needs to be energy-efficient to enable autonomous operation of wireless sensors. The environment is challenging for wireless communication regarding the propagation of electromagnetic waves due to shadowing, reflection and absorption by metallic objects and carbon-fiber materials. We present an approach where spatially distributed redundant access points are used to reliably communicate with wireless sensors and actuators without sacrificing end-to-end latency even in non-line-of-sight conditions. The wireless sensor network is analyzed by means of measurements in a launcher structure and by extensive simulations. The obtained results show the feasibility of the approach and the performance benefits versus state-of-the-art wireless sensor networks.