Investigating new approaches for narrowband but nevertheless high-precision wireless locating in multipath environments by means of iterative recursive non-linear state estimation techniques based on aperture synthesis and phase difference analysis in antenna array constellations

• Applicant: Professor Dr.-Ing. Martin Vossiek
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450697408

The aim of the project is to investigate a novel, low-cost but nevertheless highly accurate concept for wireless local positioning and the underlying theoretical principles, and to verify system performance both through the lens of systems theory and experimentally. The salient feature of the initiative is its potential to deliver highly accurate 3D locating results in severe multipath environments, even with narrowband signals. With previous radiolocation techniques, such as UWB radiolocation systems, the achievable positioning accuracy is typically directly dependent on the signal bandwidth used, and precise 3D positioning has rarely been demonstrated experimentally due to the challenging bandwidth requirements and the usually unfavorable geometric dilution of precision (GDOP). The expected performance of this pioneering solution, which would represent an enormous improvement over the state of the art, is to be achieved by iterative recursive nonlinear state estimation techniques. For this purpose the phase differences of the radio signals received in mixed coherent/incoherent antenna arrays constellations will be evaluated in a way comparable to an interferometric aperture synthesis algorithm. However, instead of using of Fourier or other spectral estimation techniques the phase values are directly processed by an iterative Extended Kalman Filter (EKF). Having studied the system proposed in this project and implemented the necessary algorithms, the system will be systematically investigated in a simulation environment and then tested in practice in an experimental setup. The 24 GHz experimental system to be implemented during the project comprises four distributed compact receiver arrays with 16 antennas each. The aim of the project is to demonstrate for the first time 3D positioning accuracy in the millimeter range for signals with a bandwidth of less than 10 MHz in a dense multipath environment. The development of a new general-purpose methodology for validating positioning systems is another key aspect of the research work. This is necessary because commonly used GDOP-based methodologies for predicting/estimating positional uncertainties as a function of system parameters are unsuitable for the methodology adopted in this project, where the acquisition and fusion of the measurements are integrated. The aim is to create a platform based on the new theoretical model. This platform will allow classical localization principles and this new solution to be compared systematically and objectively for the first time with respect to performance as a function of the system parameters and also with respect to the parameters that take into account the transmission channel and multipath propagation.

• DFG Programme: Research Grants