Tom Schipper

UWB localization system for indoor applications: concept, realization and analysis

A complete impulse-based ultrawideband localization demonstrator for indoor applications is presented. The positioning method, along with the method of positioning error predicting, based on scenario geometry, is described. The hardware setup, including UWB transceiver and time measurement module, as well as the working principles is explained. The system simulation, used as a benchmark for the quality assessment of the performed measurements, is presented. Finally, the measurement results are discussed. The precise analysis of potential error sources in the system is conducted, based on both simulations and measurement. Furthermore, the methods, how to improve the average accuracy of 9 cm by including the influences of antennas and signaldetection threshold level, are made. The localization accuracy, resulting from those corrections, is 2.5 cm.

Realization Limits of Impulse-Based Localization System for Large-Scale Indoor Applications

In this paper, a 3D indoor localization demonstrator on the basis of impulse-radio ultrawideband (UWB) technology and time-difference-of-arrival (TDOA) principle is developed and analyzed. The parameters of the transmitter and receiver hardware components are investigated to determine their influence on the localization performance. The signal detection method based on a comparator and the precise time measurement unit was examined. Two effects, namely the threshold-trigger offset and the TDOA variance errors, were quantified. Corrections methods of both these phenomena have been proposed, which delivered very good results in the experiments. With the identified and modeled inaccuracies, the Cramer-Rao lower bound for a 3D TDOA localization system is derived for the first time and verified by measurements, performed in a large-scale industrial environment. The results obtained from measurements follow closely the variance predicted by the CRLB. Moreover, the comparison with the literature published up to date proves the excellent performance of the system presented here.

24GHz Digital beamforming radar with T-shaped antenna array for three-dimensional object detection

This paper introduces a radar system for three-dimensional (3D) object detection and imaging. The presented 3D measurement method combines the frequency-modulated continuous wave (FMCW) approach for range measurements with a multiple-input multiple-output (MIMO) technique for digital beamforming in two dimensions. With an orthogonal arrangement of the antenna arrays for transmit and receive, the angular information is obtained in azimuth and elevation without mechanical beamsteering. The proposed principle allows performing 3D imaging by means of the acquired range, azimuth, and elevation information with a minimum of required hardware. Starting from the realization of the 3D radar imaging concept, the hardware architecture and the developed prototype are discussed in detail. Furthermore, the object detection capability of the 3D imaging radar system is demonstrated by measurements. The results show that the introduced 3D measurement concept in its realization is well suited for numerous applications.

Simulative Prediction of the Interference Potential Between Radars in Common Road Scenarios

This paper provides qualitative and quantitative values for the received interference power at the antenna ports of automotive radars as well as the probability of their occurrence for actual and future, not yet measurable traffic scenarios on main roads. The influence of the environment, the road traffic behavior, and the radar penetration rate for a defined antenna configuration can be observed. The basis for the analyses are ray-tracing based simulations in order to achieve adequate predictions for the received power levels due to multipaths. The results show that for a radar penetration rate of 100%, the difference between the strongest overall incoherent received interference power level and the level that is received in 90% of the time is up to 7 dB, dependent on the antenna placement and the environment.

Discussion of the operating range of frequency modulated radars in the presence of interference

This paper discusses the operating range of frequency modulated (FM) radars in the presence of interference. For this purpose, radar- and path loss equations are used to draw the equipotential lines for a given signal-to-interference ratio as a function of the spatial distribution of targets and interferers in order to identify relevant scenario constellations. Further the factors influencing the gain of signal versus deterministic interference are discussed based on measurements and simulations. Finally, the influence of different kinds of interference on the spectrum of a frequency modulated continuous wave radar is shown.

Simulation framework for the estimation of future interference situations between automotive radars

Interference between automotive radar systems is becoming an important topic of research today, since the density of automotive radars is rising continuously. However, the total amount of cars equipped with radar is still below one percent. This paper introduces a method to predict future interference conditions between automotive radars for higher penetration rates and presents selected results.

Realization of a pattern reconfigurable antenna employing PIN diodes

A compact pattern reconfigurable antenna for mobile communication is presented in this work. The presented antenna shows a good matching between 1.5 GHz and 2.5 GHz. It can therefore be applied for the 1.8 GHz mobile communication band and for the 2.4 GHz WiFi (wireless fidelity) band. Furthermore the antenna is capable of switching between three different directivity patterns. An omnidirectional pattern is realized in one of the states. The two other states generate a directional beam. The beams are shifted by 180° in azimuth and directed towards opposite sides of the antenna. The antenna elements can be switched between activated with the use of PIN diodes. With the chosen construction the PIN diodes can be easily fed with the help of a coaxial bias-T and a simple feeding structure. The measurement results prove a good performance of the antenna.

A simulator for multi-user automotive radar scenarios

Radar is an essential element of state of the art advanced driver assistance systems. In the foreseeable future, radar will be an indispensable sensor for the use in affordable, automated driven cars. Simulation tools are the key for an efficient development process and hence will lower the price of sophisticated driver assistance systems. Therefore, the development of adequate simulators is important for suppliers, car makers, and final consumers. This paper introduces the concept of such a simulator for multi-user automotive radar scenarios and presents selected simulation results for a use case of radar interference.

A pattern reconfigurable automotive LTE antenna employing synthesized radiation patterns

This work presents a pattern reconfigurable automotive antenna optimized for the 2.6GHz band reserved in Europe for the use of the Long Term Evolution (LTE) communication standard. Pattern reconfiguration is the ability of an antenna to switch between at least two fixed radiation patterns (states). In this work a special feeding network utilizing PIN diodes is used to switch between the two states. One possible trigger for the switching from one to another reconfiguration state is a bad SNR, a condition to achieve a diversity gain. A special antenna synthesis method was used to determine the antenna radiation patterns to be used for pattern reconfiguration. Finally the antenna is simulated, fabricated and measured.

“Virtual Drive” physical layer simulations for Vehicle-to-Vehicle communication

Future mobile communications, in the mean of Car-to-Car (C2C), Car-to-Infrastructure (C2I) or Vehicle-to-Vehicle (V2V) communication, will make use of multiple antenna systems like diversity or MIMO. Especially in multiple antenna systems finding the optimal antenna configuration in order to ensure the best performance is a very difficult task. Presently antennas in mobile communications systems, especially in cars, are selected in a rather expensive and time consuming test-drives, if at all. This will not be technically possible and affordable for multiple antenna systems in the future. Here a solution for this problem is demonstrated defined as Virtual Drive. In the Virtual Drive the quality of the antenna system is determined by simulating the mobile, driving through the EM-fields radiated from the transmitter. The multi-path propagation from the transmitter is calculated by a 3D ray-tracing tool, which is based on the theory of geometrical optics (GO) and the Uniform Theory of Diffraction (UTD). The combination of both yields a “virtual drive” through any scenario and allows optimization of antenna configurations without extensive measurement campaigns and without prototyping all configurations to be investigated. Additionally Virtual Drive provides a perfect repeatability of the testing environment.