Performance Bounds for Anchorless Cooperative Indoor Localization Exploiting Multipath

Authors

Gregor Dumphart

Reference

Master’s Thesis, Graz University of Technology, Mar. 2014.

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Abstract

There is high demand for accurate indoor localization for use in logistic, industrial, and commercial systems. However, due to multipath propagation, localization is a difficult task in indoor environments. Available accurate solutions require costly, inflexible infrastructure in terms of several fixed physical anchors. The multipath-assisted indoor navigation and tracking (MINT) approach assumes a known floor plan, which enables multipath-assisted localization through mapping multipath components to virtual anchors. So, cost can be saved by reducing the number of required fixed physical anchors. Cooperative MINT (Co-MINT) is an advanced, more flexible concept that allows for anchorless localization. It assumes several cooperating mobile agents equipped with ultra-wideband (UWB) transceivers that perform monostatic and bistatic measurements, share these observations, and estimate the agent positions jointly. A proof of concept has been presented in a recent work, but a quantitative assessment of the localization performance was not given. The goal of this master thesis is to obtain a performance bound for Co-MINT. In a first step, the dependence of multipath propagation delays on the room geometry is studied to obtain a general formula for spatial delay gradients which express the influence of the indoor geometry on the localization performance. Next, the thesis analyses monostatic localization as a building block of Co-MINT. The derivation of the Cram´er-Rao lower bound (CRLB) of monostatic position estimation and numerical results thereof are presented. The ranging information provided by particular monostatic multipath geometries is examined. The final part of the thesis contains a derivation of the CRLB for Co-MINT and gives the corresponding equivalent Fisher information matrix (EFIM). Numerical results reveal characteristics of cooperation and show the behaviour of the position error bound (PEB) for several scenarios


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