Journal ArticleDOI
Localization of Narrowband Radio Emitters Based on Doppler Frequency Shifts
Alon Amar,Anthony J. Weiss +1 more
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TLDR
A single-step approach based on the maximum likelihood criterion is proposed here for both known and unknown waveforms and it is shown that in some cases of interest the proposed method inherently selects reliable observations while ignoring unreliable data.Abstract:
Several techniques for emitter localization based on the Doppler effect have been described in the literature. One example is the differential Doppler (DD) method in which the signal of a stationary emitter is intercepted by at least two moving receivers. The frequency difference between the receivers is measured at several locations along their trajectories and the emitter's position is then estimated based on these measurements. This two-step approach is suboptimal since each frequency difference measurement is performed independently, although all measurements correspond to a common emitter position. Instead, a single-step approach based on the maximum likelihood criterion is proposed here for both known and unknown waveforms. The position is determined directly from all the observations by a search in the position space. The method can only be used for narrowband signals, that is, under the assumption that the signal bandwidth must be small compared to the inverse of the propagation time between the receivers. Simulations show that the proposed method outperforms the DD method for weak signals while both methods converge to the Cramer-Rao bound for strong known signals. Finally, it is shown that in some cases of interest the proposed method inherently selects reliable observations while ignoring unreliable data.read more
Citations
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Journal ArticleDOI
Bias Reduction for an Explicit Solution of Source Localization Using TDOA
TL;DR: Analysis shows that both methods reduce the bias considerably and achieve the CRLB performance for distant source when the noise is Gaussian and small and the BiasRed method is able to lower the bias to the same level as the Maximum Likelihood Estimator.
Journal ArticleDOI
Cooperative Positioning for Vehicular Networks: Facts and Future
N. Alam,Andrew G. Dempster +1 more
TL;DR: The general performance boundaries for modern CP systems are explained, as is the gap existing between the positioning accuracy required for crucial ITS applications and what modern CP can provide, followed by introduction of a novel trend for vehicular CP research.
Journal ArticleDOI
Direct Geolocation of Wideband Emitters Based on Delay and Doppler
TL;DR: A direct position determination approach that proves to be more computationally efficient and more precise for weak signals than the conventional approach and a derivation of closed-form and compact expressions of the Cramér-Rao lower bound.
Journal ArticleDOI
Relative Positioning Enhancement in VANETs: A Tight Integration Approach
TL;DR: A CP method is presented to improve the relative positioning between two vehicles within a VANET, fusing the available low-level Global Positioning System (GPS) data.
Journal ArticleDOI
TOA-Based Robust Wireless Geolocation and Cramér-Rao Lower Bound Analysis in Harsh LOS/NLOS Environments
TL;DR: This work develops an iterative algorithm for robust position estimation that approximates the exact measurement error PDF under the current parameter estimate via adaptive kernel density estimation, and resolves a position estimate from the approximate log-likelihood function via a quasi-Newton method.
References
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Statistical theory of d.f. fixing
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