Wireless communication with chaos

Peer reviewedPublisher PD

Multipath propagation simulator for V2X Communication Tests on Cars

Test and evaluation of wireless communication performance with cars can be done in many ways. One approach, for both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) tests, is to use a multipath propagation simulator to achieve realistic signal environments for the different communication systems under test. Multipath propagation simulators have previously been shown to be useful for testing mobile handsets. Specific issues related to tests with cars are the large size of the test object and the disturbances it can cause. In this paper we experimentally study how different design parameters of the multipath propagation simulator affect the received signals. The analysis of the setup as well as the data is performed using the so-called “Design of Experiments” method

Practical Accuracy Limits of Radiation-Aware Magneto-Inductive 3D Localization

The key motivation for the low-frequency magnetic localization approach is that magnetic near-fields are well predictable by a free-space model, which should enable accurate localization. Yet, limited accuracy has been reported for practical systems and it is unclear whether the inaccuracies are caused by field distortion due to nearby conductors, unconsidered radiative propagation, or measurement noise. Hence, we investigate the practical performance limits by means of a calibrated magnetoinductive system which localizes an active single-coil agent with arbitrary orientation, using 4 mW transmit power at 500 kHz. The system uses eight single-coil anchors around a 3m x 3m area in an office room. We base the location estimation on a complex baseband model which comprises both reactive and radiative propagation. The link coefficients, which serve as input data for location estimation, are measured with a multiport network analyzer while the agent is moved with a positioner device. This establishes a reliable ground truth for calibration and evaluation. The system achieves a median position error of 3.2 cm and a 90th percentile of 8.3 cm. After investigating the model error we conjecture that field distortion due to conducting building structures is the main cause of the performance bottleneck. The results are complemented with predictions on the achievable accuracy in more suitable circumstances using the Cram\'er-Rao lower bound.Comment: To appear at the IEEE ICC 2019 Workshops. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Chaos-based wireless communication resisting multipath effects

This work is supported by NSFC (China) under Grants No. 61401354, No. 61172070, and No. 61502385; by the Innovative Research Team of Shaanxi Province under Grant No. 2013KCT-04; and by Key Basic Research Fund of Shaanxi Province under Grant No. 2016JQ6015.Peer reviewedPublisher PD

Multipath and interference errors reduction in gps using antenna arrays

The Global Positioning System (GPS) is a worldwide satellite based positioning system that provides any user with tridimensional position, speed and time information. The measured pseudorange is affected by the multipath propagation, which probably is the major source of errors for high precision systems. After a presentation of the GPS and the basic techniques employed to perform pseudorange measurements, the influence of the multipath components on the pseudorange measurement is explained. Like every system the GPS is also exposed to the errors that can be caused by the interferences, and a lot of civil applications need robust receivers to interferences for reasons of safety. In this paper some signal array processing techniques for reducing the code measurement errors due to the multipath propagation and the interferences are presented. Firstly, a non-adaptive beamforming is used. Secondly, a variant of the MUSIC and the maximum likelihood estimator can be used to estimate the DOA of the reflections and the interferences, and then a weight vector that removes these signals is calculated. In the third place, a beamforming with temporal reference is presented; the reference is not the GPS signal itself, but the output of a matched filter to the code. An interesting feature of the proposed techniques is that they can be applied to an array of arbitrary geometry.Peer ReviewedPostprint (published version

A system model for multipath interference on terrestrial line-of-sight QAM digital radio

A comprehensive system model for characterizing the effects of multipath propagation on digital radio systems in the 4 to 6 GHz band is shown in this thesis. The effects of terrain-induced multipath propagation in the presence of atmospheric anomalies are studied using data from experimental microwave links in the field and in the laboratory. This technique, which treats multipath propagation as digital signal distortions caused by interference from ground reflections, has not been shown previously. A forward multipath propagation model is used to identify the critical propagation parameters for a QAM signal. A normalized two ray channel model is developed to approximate the frequency response produced by interference from a ground reflection in a narrow band. The effectiveness of this channel model is evaluated using measured data from the test radio link in the field. The channel parameter values are also estimated from these data. Using the channel model, the channel distortions are simulated in the laboratory. The performance of the laboratory test link is characterized to identify the critical parameters for a QAM receiver model. This receiver model is then used to simulate digital signal distortions and a metric is developed for digital signal distortion as a function of multipath interference