Andreas Ziroff

Indoor Localization of Passive UHF RFID Tags Based on Phase-of-Arrival Evaluation

This paper introduces a two-dimensional localization system for passive UHF RFID transponders based on phase-of-arrival evaluation of the backscattered tag signal. A multiple-channel system, where alternately one path is configured as a transmitter and the remaining paths work as receivers, is used to permit the position estimation. To improve localization accuracy and reduce disturbances caused by multipath propagation, a frequency-stepped continuous-waveform approach is employed. To achieve proof of concept, a local position measurement system demonstrator comprising an RFID reader, passive EPC Gen 2 RFID tags, several transceivers, baseband hardware, and signal processing was used for measurements. The results show excellent localization accuracy, even in an indoor environment.

Local Positioning for Wireless Sensor Networks

This workshop paper gives an overview of local positioning and tracking principles for wireless sensor networks including recent results of the European project RESOLUTION (reconfigurable systems for mobile local communication and positioning). Measurements of a first demonstrator applying a frequency modulated continuous wave (FMCW) radar principle are presented. The unlicensed ISM band around 5.8 GHz, 150 MHz bandwidth and less than 25 mW effective isotropic radiated transmit power are used. Excellent 3-D positioning accuracies in the order of 4 cm in an anechoic chamber and 18 cm in a conference hall with strong multipath and area of 800 m2 are measured. Furthermore, the results of optimized radio frequency integrated circuits and a suitable compact flash card are outlined.

A novel approach for LTCC packaging using a PBG structure for shielding and package mode suppression

A packaging solution for multifunctional modules up to an operating frequency of 50 GHz based on Low Temperature Cofired Ceramics (LTCC) is presented in this paper. A Ball Grid Array (BGA) as well as a Land Grid Array (LGA) transition from Printed Circuit Board (PCB) into a surface mounted module are proposed. They use a Photonic Bandgap (PBG) structure to suppress the excitation of parasitic modes e.g. by the SMT interconnect. This approach provides process tolerant transitions as well as it allows the integration of wave guide structures in buried layers. This measure provides a greater flexibility in the design of microwave circuits and a major potential for miniaturisation of microwave subsystems.

Novel MIMO Antennas for Mobile Terminal

Radiation from a small device is dominated by the chassis, not only by the antenna structure attached to it. We propose a MIMO antenna system considering the mobile phone chassis as the main radiator. Since the chassis supports multiple orthogonal mode currents at a certain frequency, we couple to four of these modes using four miniature capacitive couplers to realize a four port antenna system. Although impedance characteristics of different modes are inherently different, matching at the system ports is sufficient to use this MIMO antenna system for 2.4 GHz ISM band.

3D-Accuracy Improvements for TDoA Based Wireless Local Positioning Systems

Local positioning systems significantly enhance the value of wireless sensor networks (WSN). This paper gives an overview of local positioning system topologies for WSNs of the European project RESOLUTION, which operate in the unlicensed ISM band at 5.8 GHz with 150 MHz bandwidth and allowed 25 mW effective isotropic radiated transmit power. The achievable 3D-localization accuracy is analyzed with respect to the performance of the designed hardware components and the indoor environment. It is further shown that accuracy as a primary attribute of local positioning systems also affects secondary quality-of-service (QoS) features such as update-rates or latency. This investigation allows an optimization of both attributes simultaneously, primary and secondary QoS aspects.

A Reconfigurable MIMO System for High-Precision FMCW Local Positioning

In this paper, a highly accurate local positioning system is presented that is based on linear frequency-modulated continuous-wave signals in the 5.8-GHz industrial-scientific-medical band. The developed system allows for much higher operating distances than leading ultra-wideband local positioning systems, while it provides the same or even better accuracy. This is achieved by a novel multiple-input multiple-output (MIMO) measurement concept that enables the receiving unit to control the beam patterns of the receiving and the transmitting antenna arrays by a coherent combination of the received signals. In this way, interfering multipath components are suppressed, leading to a significantly reduced ranging error. Furthermore, the angle of arrival and the angle of departure are determined from the MIMO datasets using super-resolution direction-finding techniques. For position determination, both range and angle information are exploited. Extensive measurements with the MIMO system in different indoor environments show that the position error can be reduced by up to 80% compared to an equivalent single-antenna setup.

A 40 GHz LTCC receiver module using a novel submerged balancing filter structure

A SMT compatible 40 GHz discrete mixer in LTCC is proposed. A novel filter structure was implemented in a buried layer, which serves as a balun for a discrete balanced mixer at the same time. The design approach scales very well with frequency and stopband specification and allow the design of compact low cost modules.

Phase-of-arrival-based localization of passive UHF RFID tags

This paper introduces a novel 2D localization system for passive UHF RFID tags based on phase-of-arrival evaluation of the backscattered tag signal received by several antennas. To improve localization accuracy and reduce disturbances caused by multipath propagation, we employ a frequency-stepped continuous waveform approach. To achieve proof of concept, a local position measurement system demonstrator comprising an RFID reader, passive EPC Gen 2 RFID tags, several receivers, baseband hardware, and signal processing was used for measurements in an anechoic chamber.

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.

A Novel Approach for a Periodic Structure Shielded Microstrip Line to Rectangular Waveguide Transition

A microstrip line to rectangular waveguide transition at 77 GHz is presented in this paper. The transition based on a resonant slot aperture is processed on a metal reinforced soft substrate. A periodically structured shield is used to suppress the emissions and the parallel plate modes which helps to increase the performance of the transition. The simple fabrication enables the design of low cost radar modules on a PCB substrate with a rectangular waveguide interface.