Bernhard Auinger

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.

Calculation of very near field radiated emission of a straight cable harness

Radiated emissions generated by an integrated circuit (IC) during operation must not exceed specific limits. For automotive ICs this is verified by the standardized ALSE (Absorber Lined Shielded Enclosure) measurement setup defined in the CISPR 25 standard. This test especially targets the E-field emitted by a long cable harness attached to the device under test. Apart from simulations, analytical calculation models can be applied to quickly estimate the compliance test results. Typically the Hertzian dipole antenna model is used to calculate the electric field radiating from cables. But during the ALSE test radiated emissions from 150 kHz to 1GHz are measured in 1m distance. This results in very near field conditions for the lower frequencies, where the common prediction model is at its theoretical limits. As an alternative this paper demonstrates an electrostatic approach. For the frequency range of 100 kHz to 30MHz constant transmission factors are derived which yield the radiated emission spectrum when applied to the ICs output signal spectrum. The results of both calculation models are compared to measurement data.

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.

Validation of the Decomposition Method for Fast MIMO Over-the-Air Measurements

Over-the-air (OTA) throughput tests of wireless Multiple-Input Multiple-Output (MIMO) devices are an important tool for network operators and manufacturers. The user equipment (UE) is placed in an anechoic chamber and a random fading process is emulated by a base-station emulator (BSE). The antenna characteristic of the UE is taken into account by sampling the sphere around the UE with the BSE test antenna at a large number of positions. For low-variance throughput results, long measurement intervals over many fading realizations are required, leading to long and expensive measurement periods in an anechoic chamber. To speed up the OTA test, we analyze the Decomposition Method (DM). The DM splits the throughput measurement into two parts: (1) a receiver algorithm performance tests taking the fading process into account and (2) an antenna performance test without fading process emulation. Both results are combined into a single throughput estimate. The DM allows for a measurement time reduction of more than one order of magnitude. We provide an analytic and numerical analysis as well as measurements. Our detailed results show the validity of the DM in all practical settings.

On the Envelope Correlation Coefficient of an LTE Reference Antenna System for Band 13

This document presents the investigations on two coupled reference antennas for LTE Band 13 (uplink 777MHz to 787MHz, downlink 746MHz to 756MHz). An important figure of merit to quantify coupling effects in multiple input multiple output (MIMO) antenna systems is the envelope correlation coefficient (ECC). The single antenna element is presented with radiation pattern and scattering parameters. It is a planar device, easy to be etched or milled as dimensions are given. The ECC investigations were done by measurement and simulation, the results are presented and compared. A good agreement between the simulated and the measured ECC can be recognized. In wireless data transmission the use of Multiple Input Multiple Output (MIMO) antenna technology introduces yet another degree of freedom and vastly rises the reachable data throughput. Transmission systems take advantage of the several different propagation paths. They send different data streams through multiple antennas on different paths through the wireless channels. Receivers pick up the mixed data streams. By orthogonalization in the receiver these paths can be treated as separated ones. The less the received data are correlated, the higher is the performance of the transmission system. Simply spoken, unnecessary introduction of data correlation has to be avoided in all stages of the transmission. Looking at small sized hand held user equipment (UE) it is likely that antennas are closely spaced to each other. This proximity introduces unwanted coupling effects and in this way correlation, which results in a performance degradation. (1)-(15) perform similar investigations, but deal with antennas for other purposes. This paper shows an investigation of the ECC on an antenna setup with two coupled dipoles for LTE band 13.