Lars Reichardt

Extension of the OFDM joint radar-communication system for a multipath, multiuser scenario

In this paper an extension of the OFDM joint radar and communication system concept to cope in a multipath and multiuser environment is explored. A realistic multipath propagation channel model is built with an established ray-tracing algorithm and incorporated into the radar system simulation and one additional user/interferer is then introduced into the scenario for the observation of the radars performance. From a theoretical point of view as well as from measurement results, the interferer causes a severe degradation of the radars dynamic range, thus requiring an interference cancellation scheme to remove the traces of the interferer. Inherent to the interference cancellation scheme is the phase and frequency offset estimation algorithm for the high fidelity reconstruction of the interferer signal for subtraction from the radar signal which are explored in this paper. The result of the end-system and the improvement to the radars dynamic range are then presented.

Virtual Drive: A Complete V2X Communication and Radar System Simulator for Optimization of Multiple Antenna Systems

Vehicle-to-X (V2X) communication as well as automotive radar are fast growing areas of consumer interest. This gives rise to a challenge to a well-working communication systems in handling the V2X radio channel. The two most important components influencing the channel are the antennas and the fast changing environment, resulting in a time-variant behavior of the channel. Therefore, finding the optimal antenna configuration to ensure the best performance is a difficult task. A possible solution is the employment of measurement campaigns, but they are expensive, time consuming, and provide no repeatability. An alternative approach, based on simulations, is presented in this article. This tool, called “Virtual Drive,” consists of an environment and a traffic model and calculates the multipath propagation with a 3D ray-tracing tool. This combination yields a “virtual drive” through arbitrary scenarios and allows for the optimization of antenna configurations that are to be investigated. The different components of the Virtual Drive are described and the accuracy of the software tool is examined by a comparison with measurements. Finally, the manifold capabilities of such a software tool are demonstrated using the example of vehicular antenna optimization for cars and of radar system optimization.

On polarization diversity gain in short range UWB-Radar object imaging

In this paper a 2D bi-static, fully-polarimetric Ultrawideband (UWB) imaging system is presented. The exploitation of polarization diversity provides supplemental information compared to mono-polarized sensing techniques. This polarization diversity gain enhances the efficiency of target classification according to information contained in the back-scattered signal. Hence, additional characteristics of targets such as form, details of surface structure and orientation are gathered, which may remain invisible for mono-polarized systems. An experimental validation is carried out based on complex test objects, an M-sequence Radar device and new dual-orthogonal polarized antennas.

Performance evaluation of SISO, SIMO and MIMO antenna systems for car-to-car communications in urban environments

This paper evaluates single and multiple antenna systems in realistic car-to-car communication channels. With a three-dimensional ray-tracing simulation tool the narrow-band channel characteristics are determined for various antenna positions and numbers of antennas. The results clearly show the advantage of multiple antenna systems. Suitable antenna positions are determined that allow for optimizing the signal-to-noise ratio and the channel capacity.

Simulation and Evaluation of Car-to-Car Communication Channels in Urban Intersection Scenarios

This paper evaluates multiple antenna systems in realistic Car-to-Car (C2C) communication channels for urban intersection scenarios. With a three-dimensional ray-tracing simulation tool the channel characteristics are determined for various antenna positions and numbers of antennas. The results clearly show the advantage of multiple antenna systems. Suitable antenna positions are determinedthatallowtheoptimizationofthe channel capacity ( )However, in spite of the benefits of route specific infor- mation, the amount of data to be processed and transmitted presents a great challenge. Other road users as well as the surroundings influence the channel in a complex manner. It follows that a detailed knowledge about the inter-vehicle trans- mission channel is necessary for the design and optimization

Shape Memory Alloy (SMA)-Based Pattern-Reconfigurable Antenna

This letter presents a realization method of reconfigurable antenna systems based on smart materials. The reconfigurability is obtained by utilizing shape memory alloy directors. This realization method offers a longer lifetime and lower energy consumption than conventional approaches such as microelectromechanical systems (MEMS) or p-i-n diodes. As a proof-of-concept, a compact reconfigurable antenna for the 2.6-GHz Long Term Evolution (LTE) band was designed. The designed antenna is a quasi-Yagi antenna with its directors made from shape memory alloy. This antenna is made to be installed in a standard car-roof antenna housing. A prototype of the antenna presented here has been fabricated and measured.

Virtual Drives in Vehicular Communication

The fast and economical prototype development of (vehicular) antenna systems requires the employment of feasible simulators. This article describes such a simulator for vehicular communications. The channel model used is based on stochastically or deterministically generated 3-D environments that include a realistic traffic model. The wave propagation is calculated with a fully polarimetric ray tracing tool. In addition, an antenna synthesis method for predefined time-variant communication scenarios has been proposed. The major emphasis has been put on MIMO systems, but in general, the algorithm can be employed for multiple-element as well as single-element antenna systems.

Investigation on Antenna Systems for Car-to-Car Communication

This paper introduces a novel method for the investigation of antenna systems in Car-to-Car communication channels. With a three-dimensional ray-tracing simulation tool the channel characteristics are determined for various antenna positions and numbers of antennas in realistic car-to-car communication channels for urban intersection scenarios. Then an antenna synthesis method is used to determine the optimum current distributions for each subchannel, i.e. the optimum radiation patterns, in order to investigate the communication limits of those channels. As result it is seen, that for this type of scenarios antenna placement is decisive in the system performance. Furthermore, it is shown that under the studied configuration, multiplexing effects could not be exploited and that placement of the antennas below the car is more robust toward scenario changes.

Compact, Teflon embedded, dual-polarized ultra wideband (UWB) antenna

In this paper a compact dual-polarized Ultra Wideband antenna applicable to an indoor radar is presented. Apart from a broad bandwidth, which is between 3.5 to 13.5 GHz, the main features are high polarization purity and small dimensions. The compact size is determined by the embedding in a dielectric (Teflon). The antenna itself is tapered slot lines based, typically known as Vivaldi antennas. Additionally to the description of the design also measurement results of a prototype are presented.

Improved Detection Scheme for Chipless RFIDs Using Prolate Spheroidal Wave Function-Based Noise Filtering

A novel, highly sensitive scheme to detect the resonance peaks in the spectrum of chipless RFID signals is presented. The detection is based on finding the zeros in the derivative of the group delay of the received signal. In order to be able to accurately detect these zeros in the presence of noise, the received signal is filtered using a prolate spheroidal wave function-based model. This allows great increases in the distance at which chipless RFIDs can be accurately read. The detection method can be used standalone or in addition to traditional amplitude-based detection schemes.