Heynicke, Ralf

Reverberation chambers (RCs) can be used as repeatable and shielded test environments for electromagnetic compatibility testing and performance evaluation of wireless com-munication devices, as they inherently emulate a Rician/Rayleigh fading environment. Loading a RC with radio frequency (RF) absorbing material leads to an increasing coherence bandwidth (CBW) of the radio channel within the RC, where the appropriate value can be tailored to specific test specifications. In this paper the CBW is directly measured by the wireless system under test. Measurements were carried out with different loadings and the link quality indication (LQI) was used to determine an appropriate RC loading.

In the context of the Industry 4.0 initiative, Cyber-Physical Production Systems (CPPS) or Cyber Manufacturing Systems (CMS) can be characterized as advanced networked mechatronic production systems gaining their added value by interaction with different systems using advanced communication technologies. Appropriate wired and wireless communication technologies and standards need to add timing in combination with security concepts to realize the potential improvements in the production process. One of these standards is IO-Link Wireless, which is used for sensor/actuator network operation. In this paper cryptographic performance and energy efficiency of an IO-Link Wireless Device are analyzed. The power consumption and the influence of the cryptographic operations on the trans-mission timing of the IO-Link Wireless protocol are exemplary measured employing a Phytec module based on a CC2650 system-on-chip (SoC) radio transceiver. Confidentiality is considered in combination with the cryptographic performance as well as the energy efficiency. Different cryptographic algorithms are evaluated using the on chip hardware accelerator compared to a cryptographic software implementation.

Wireless communication systems are enabler technologies for modern and flexible production concepts, essentially within the Industry 4.0 directive. For reliable low-latency wireless communication, the availability of frequency spectrum is a general prerequisite. IO-Link Wireless (IOLW) is a vendor-independent wireless communication standard, which operates in the 2.4 GHz ISM (Industrial, Scientific, Medical) band and especially addresses the requirements of industrial discrete manufacturing processes. The 2.4 GHz ISM band is used by various other radio systems, making coexistence management a fundamental challenge. Blacklisting and frequency hopping schemes are specified to increase the IOLWcoexistence behavior. In this paper coexistence management methods and tools, which can be employed for IOLW are presented. These tools can be used to enhance the coexistence behavior and thus the reliability, and at the same time, reduce energy consumption. After an introduction and a detailed presentation of IOLW, a software tool is presented that allows to implement an intelligent frequency management by adapting blacklists to the respective coexistence and boundary conditions. This is based on generic measurements, which are also shown in this paper. Finally, a conclusion and an outlook for further integration into an overall system are given.

Reverberation chambers (RCs) are a feasible option as test environment for evaluation of wireless devices with integrated antenna as they inherently emulate a Rayleigh fading channel. In this paper the dependency of deep fading on the frequency and position/orientation of an equipment under test (EUT) antenna is evaluated for different numbers of RC steps and loading conditions. The measured data were applied to an exemplary standard for wireless communication. The measurement results are highly repeatable and independent of frequency or position/orientation of the EUT and loading conditions.

Reverberation chambers (RCs) are a feasible option as test environment for evaluation of wireless devices with integrated antenna, as they inherently emulate a Rayleigh fading channel. In this paper, the dependency of fading on the frequency and position/orientation of an equipment under test (EUT) antenna is evaluated in a RC and for different numbers of RC steps. The measured data were applied to an exemplary standard for wireless communication. The results suggest that the empirical probability of fading is repeatable and independent of frequency or position/orientation of the EUT.

Wireless technologies are intensively used in industrial environments and wireless sensor/actuator networks play a key role for highly flexible automation plants, especially within the Industry 4.0 initiative. In order to achieve a highly robust system behavior also an attentive antenna selection and placement within a manufacturing cell is of interest resulting in an enhanced system reserve. In this paper different strategies for base station antenna placement are investigated with the focus on star-topologies, i.e. a central base station and a multitude of remotely located wireless sensors and actuators. A probabilistic approach has been chosen for modeling path loss, multipath fading and coexistence behavior with respect to adjoining manufacturing cells. Also cable attenuation for remote antennas connected to the base station are taken into account.

Modenverwirbelungskammern (MVKn) stellen vielfältig verwendbare, reproduzierbare Messumgebungen dar. Grundsätzlich handelt es sich dabei um elektromagnetisch geschirmte Volumina, in denen sog. Modenrührer eingebracht sind, die ein elektromagnetisches Feld „verwirbeln“, sodass ein Prüfling einer definierten aber statistisch variierenden Umgebung ausgesetzt wird. Die Modenrührer in MVKn können schrittweise zwischen den einzelnen Messzeitpunkten oder kontinuierlich verfahren werden. In diesem Beitrag werden die jeweiligen Eigenschaften von wiederholten Messungen, die sowohl bei kontinuierlichem als auch schrittweisem Betrieb der Modenrührer aufgenommen wurden, betrachtet. Mit Hilfe von Korrelationskoeffizenten wird jeweils die Wiederholbarkeit der aufgenommenen Messwertsequenzen insgesamt untersucht. Darüber hinaus wird die Wiederholbarkeit von Fadingeinbrüchen gesondert betrachtet, da diese einen wesentlichen Einfluss auf Funksysteme haben, die mittels einer MVK charakterisiert werden können. Als Ursache für Abweichungen bei Wiederholungen wird abschließend das zeitliche Verhalten bzw. die Streuungen zwischen den Messzeitpunkten betrachtet.

A test method for narrowband wireless sensor/actuator networks is presented, facilitating affordable and efficient performance and compliance tests prior to the deployment of the wireless communication systems. Commonly used channel models are examined to derive a worst-case test scenario. Employing frequency/time division multiple access (F/TDMA) techniques and protocol synchronization, a new and efficient test method is suggested, where the equipment under test (EUT) is evaluated under the worst-case scenario. A cost-efficient channel emulator is introduced to emulate fading in multipath environments. Also, industrial interferes can be included in the setup. Furthermore, a procedure to test wireless devices with integrated, non-detachable antennas is presented.

In the context of the Industry 4.0 initiative, Cyber-Physical Production Systems (CPPS) or Cyber Manufacturing Systems (CMS) can be characterized as advanced networked mechatronic production systems gaining their added value by interaction with the ambient Industrial Internet of Things (IIoT). In this context appropriate communication technologies and standards play a vital role to realize the manifold potential improvements in the production process. One of these standards is IO-Link. In 2016 more than 5 million IO-Link nodes have been produced and delivered, still gaining increasing acceptance for the communication between sensors, actuators and the control level. The steadily increasing demand for more flexibility in automation solutions can be fulfilled using wireless technologies. With the wireless extension for the IO-Link standard, which will be presented in this article, maximum cycle times of 5 ms can be achieved with a probability that this limit will be exceeded to be at maximum one part per billion. Also roaming capabilities, wireless coexistence mechanisms and the possibility to include battery-powered or energy-harvesting sensors with very limited energy resources in the realtime network were defined. For system planning, setup, operation and maintenance, the standard engineering tools of IO-Link can be employed so that the backward compatibility with wired IO-Link solutions can be guaranteed. Interoperability between manufacturers is a key requirement for any communication standard, thus a procedure for IO-Link Wireless testing is also suggested.