Dominik Amschl

SDR based RFID reader for passive tag localization using phase difference of arrival techniques

This paper presents a passive radio frequency identification (RFID) reader for a two dimensional localization of tagged objects in the ultra high frequency (UHF) band. The presented prototype is capable of simultaneously estimating the direction and the range of an object. This capability is provided by a single input multiple output (SIMO) antenna configuration in combination with phase difference of arrival (PDOA) techniques. The core of the prototype is a flexible software defined radio (SDR) that allows rapid prototyping and thus a fast system verification. The reader operates at three frequencies that makes the tag localization more robust, especially in multipath environments. The reader verification is shown by measurements in an anechoic chamber. An initial angular accuracy of 3 degrees for the tag direction and 23 cm for the tag range is accomplished in this first stage of the prototype development.

SIMO RFID system performance in an engine test bed

This paper presents a performance evaluation of a radio frequency identification (RFID) system in an indoor multipath environment at 890 MHz. A single input multiple output RFID system is investigated with respect to the feasibility of localizing tagged measurement equipment in an engine test bed. Based on the available signal power within the test bed, the system performance is evaluated with respect to state-of-the-art RFID system components. The evaluations show that an exemplary RFID system experiences no outages when using a passive RFID transponder (tag) with a chip sensitivity of -17:5 dBm and an RFID reader with a transmit power of 30 dBm and a receiver sensitivity of -95 dBm. Additionally, the evaluation allows to deduce system requirement parameters for the further realization of such an RFID reader, e.g., the minimum transmit power for the reliable operation in the engine test bed is 24:5 dBm.

Virtual reality for automotive radars

Car manufacturers spend quite a lot on the development of driver assistance systems and subsequently on autonomous driving functionality. To ensure the safety and reliability of these functions meet industrial standards it is necessary to verify and validate their functionality. While tests on the road are still the ultimate evidence of correct operation they are associated with huge efforts and risks. Therefore, they have to be complemented by other means like simulations and tests on specialised testbeds. For the latter the car’s sensors have to be stimulated in a way that they perceive a desired – but only virtual – environment. An important type of sensor in cars is the radar due to its various advantages. This article describes the development of a stimulator generating virtual radar targets in order to enable the testing of autonomous driving functions.ZusammenfassungAutohersteller investieren eine hohe Summe in die Entwicklung von Fahrerassistenzsystemen und in autonomes Fahren. Es ist daher notwendig, die sichere und zuverlässige Funktion dieser Systeme zu verifizieren und zu validieren. Dies kann mit Testfahrten auf der Straße erfolgen, was aber mit großen Kosten und hohem Aufwand verbunden ist. Es wird daher daran gearbeitet, zumindest Teile dieser notwendigen Tests mit Simulationen auf Prüfständen durchzuführen. Das Radar ist ein wichtiger Sensor für die erwähnten Systeme, deshalb ist dessen Stimulation von entscheidender Bedeutung. Dieser Beitrag beschreibt die Entwicklung eines Stimulators zur Erzeugung von virtuellen Radarzielen, um autonome Fahrfunktionen auf dem Prüfstand zu testen.

Measurement based indoor SIMO RFID simulator for tag positioning

In this research, a single-input multiple-output simulator for passive UHF RFID is developed in MatlabR/SimulinkR. Tag localization is achieved via a phase difference of arrival technique. A channel measurement campaign was conducted in an engine test environment. Scattering parameters were measured at several line-of-sight and non-line-of-sight tag positions. The measured S parameters were used in the simulator to emulate a real indoor multipath channel. The simulator estimates accurate direction of arrival at several tag positions of the measurement campaign. There is a maximum error of 32° and minimum of 0.4° between the geometrically calculated and simulated angles.

A differential threshold voltage compensated RF-DC power converter for RFID tag ICs

The usage of threshold voltage (Vth) compensation techniques allows to decrease the input quality factor of RF-DC power converters or more specifically RF charge pumps at low levels of input power, and thus enable the implementation of highly sensitive broadband UHF radiofrequency identification (RFID) transponders (tags). In this work, we present a Vth compensation approach using a combination of gate and bulk biasing for differential charge pump implementations. Prototypes of an eight stage RF charge pump using the proposed Vth compensation technique have been manufactured in a low power 40 nm CMOS technology. Measurements of the test circuits reveal a high power conversion efficiency of 42.7 % and a low input quality factor of approximately 14, at an output power of 4 ßW and a DC voltage level of 1 V. Furthermore, we compare the obtained measurement results with two previously published RF charge pumps.

mm-Wave RFID for IoT applications

The internet of things (IoT) and its applications demand for solutions for small and low-power communication devices. Overcoming the drawbacks of UHF radio frequency identification (RFID) a shift of the backscatter communication principle to mm-wave frequencies is desirable. With the significant reduction of the transponder size and wider communication bandwidth, many new applications become possible. Demonstrating the feasibility, we implemented a fully functional MMID system in the E-band. Both, the base station and the transponder are investigated and their performance is presented in a system context.

Statistical analysis of the power delay profile of a SIMO UHF backscatter RFID channel in an engine test bed

The stringent constraint in any wireless communication system is the wireless channel itself. The indoor radio channel in an industrial environment exhibits a lot of multipath due to the prevalent metallic structures. In this research, an indoor radio channel is investigated in a severe multipath engine test bed environment. The study of this channel is undertaken for the applicability of a cost-efficient passive ultra high frequency radio frequency identification system capable of performing two dimensional localization of tagged objects in an engine test bed facility. The channel transfer functions were measured using a vector network analyzer. Vital channel characteristics investigated in this paper are the power delay profiles, the root mean square (RMS) delay and the power-ratio between the line of sight (LoS) and non-line of sight (NLoS) paths. The maximum RMS delay experienced is 47.1 ns and a minimum of 8.6 ns. The power-ratio values are appreciable for the majority of the LoS positions, but not satisfactory for the NLoS positions. Using this information, it will be helpful in analyzing the localization performance of a measurement-based system simulator or of a prospective hardware setup, in an engine test bed environment.