Improved position estimation using hybrid TW-TOA and TDOA in cooperative networks

Date
2012-04-13
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
IEEE Transactions on Signal Processing
Print ISSN
1053-587X
Electronic ISSN
Publisher
Institute of Electrical and Electronics Engineers
Volume
60
Issue
7
Pages
3770 - 3785
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Series
Abstract

This paper addresses the problem of positioning multiple target nodes in a cooperative wireless sensor network in the presence of unknown turn-around times. In this type of cooperative networks, two different reference sensors, namely, primary and secondary nodes, measure two-way time-of-arrival (TW-TOA) and time-difference-of-arrival (TDOA), respectively. Motivated by the role of secondary nodes, we extend the role of target nodes such that they can be considered as pseudo secondary nodes. By modeling turn-around times as nuisance parameters, we derive a maximum likelihood estimator (MLE) that poses a difficult global optimization problem due to its nonconvex objective function. To avoid drawbacks in solving the MLE, we linearize the measurements using two different techniques, namely, nonlinear processing and first-order Taylor series, and obtain linear models based on unknown parameters. The proposed linear estimator is implemented in three steps. In the first step, a coarse position estimate is obtained for each target node, and it is refined through steps two and three. To evaluate the performance of different methods, we derive the Cramér-Rao lower bound (CRLB). Simulation results show that the cooperation technique provides considerable improvements in positioning accuracy compared to the noncooperative scenario, especially for low signal-to-noise-ratios.

Course
Other identifiers
Book Title
Keywords
Cooperative positioning, Cramér-Rao lower bound (CRLB), Linear estimator, Maximum-likelihood estimator (MLE), Time-difference-of-arrival (TDOA), Time-of-arrival (TOA), Two-way time-of-arrival (TW-TOA), Wireless sensor network, Cooperative positioning, Linear estimators, Lower bounds, Maximum-likelihood estimator (MLE), Time-difference-of-arrival, Time-of-arrival, Maximum likelihood estimation, Wireless sensor networks, Sensor nodes
Citation
Published Version (Please cite this version)