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In this paper an algorithm for time of arrival estimation is proposed, which allows processing of spectrally sparse channel observations in order to provide highly accurate range estimations with a maximized resolution capability. The use of sparse waveforms in combination with the presented algorithm provides increased spectral efficiency with lower computational complexity due to reduced size of...
Many emerging technologies for wireless networks (WNs) require decentralized synchronization and ranging, i.e., distance estimation between neighboring pairs of nodes. Both tasks are related to each other when they are based on time measurements between nodes. Revealing this connection, we present a mean field (MF) message passing algorithm for cooperative simultaneous ranging and synchronization...
In this paper, we introduce a novel direction of arrival (DOA) estimation algorithm for an array presenting multiple scales of invariance, based on a CANDECOMP/PARAFAC (CP) model of the data. The proposed approach is a generalization of the results given in [1] to an array presenting an arbitrary number of spatial invariances. We show, on a particular array geometry, that our method could out-perform...
Localization is a fundamental challenge for any wireless network of nodes, in particular when the nodes are mobile. For an anchorless network of mobile nodes, we present a relative velocity estimation algorithm based on multidimensional scaling. We propose a generalized two-way ranging model, where the time-varying pairwise distances between the nodes are expressed as a Taylor series for a small observation...
Ranging performance is a fundamental and crucial figure of merit for any position estimation technique. Cooperative positioning requires accurate range estimation with low latency. Common solutions employ time slots to sequentially range among all possible mobile nodes. In this case the number of ranging links increases quadratically with the number of users which increases latency significantly....
Ranging errors are inevitable in all local positioning systems, including those based on Time-of-Flight (ToF) technique. Results of experiments show that the major cause for these errors is a signal degradation from multipath propagation. This effect is especially critical in case of Non-Light-of-Sight (NLOS) conditions. This paper describes causes that affects ranging errors for nanoLOC™-TOF-technology...
Localization of wireless ad hoc and sensor networks has gained research attentions for several years. This paper proposes a hybrid localization scheme which exploits Received Signal Strength (RSS)-based ranging and Self Organizing Maps (SOM)-based range free localization methods to obtain the tradeoff between cost, power and location accuracy. By utilizing RSS-based distance estimation and connectivity...
I survey the state of the art on high-precision position estimation in indoor environments with a focus on our own work at the Freie Universita¨t Berlin. Indoor position estimation methods are introduced and shown to be sensitive to underlying assumptions on errors distributions. Performance of algorithms is shown to be location dependent. We compare results obtained by simulation to results obtained...
Localization is one of the fundamental problems in wireless sensor networks (WSNs), since locations of the sensor nodes are critical to both network operations and to most of the application level tasks. There exists an extensive body of paper that aims at obtaining locations as well as spatial relations of nodes in WSNs without requiring specialized hardware and/or employing only a limited number...
The localization of sensor networks using positioning systems rather than a GPS device is of great interest in many real world applications. One of the systems involves a circular type localization using distance measurements, where the problem of localizing a free sensor with knowledge of three anchors in a 2D plane is formulated using the Cayley-Menger determinant with no closed-form solution. Under...
Wireless Sensor Networks (WSNs) are composed of nodes that gather metrics such as temperature, pollution or pressure from events generated by external entities. Localization in WSNs is paramount, given that the collected metrics must be related to the place of occurrence. This work presents an alternative way towards localization in randomly deployed WSNs based on the combination of individual position...
A method for estimating the range between moving vehicles by using a monocular camera is proposed. Although most conventional methods use vertical triangulation, the proposed method uses both vertical and horizontal triangulation, which reduces errors due to vehicle's own pitching in the far distance. Unknown vehicle width is estimated by measuring three ranging parameters associated with an image...
High-accuracy localization in harsh environments is a challenging research problem, mainly due to non-line-of-sight (NLOS) propagation, multipath effect, and multiuser interference. Many techniques have been proposed to address this problem; most of them focus on improving the accuracy of ranging estimation, e.g., NLOS identification and mitigation. In this paper, we take ranging one step further...
This paper presents a novel cognitive and cooperative tracking (CCT) approach based on extended Kalman filter (EKF) to localize mobile nodes in wireless networks. The proposed algorithm shows three important features: energy efficient, cognitive and cooperative. More specifically, the tracking algorithm adaptively adjusts the transmission power to optimize the energy consumption while meeting the...
Several important network functionalities such as routing and localization rely on correct neighbor discovery. In wormhole attacks the adversary tunnels the packets from one to another area to mislead the nodes in those typically far away areas to believe to be neighbors. In this paper we propose Robust Secure Neighbor Discovery (RSND) which is a distributed neighbor discovery protocol to prevent...
The main challenge of indoor wireless positioning is the large positive bias of non-line-of-sight (NLOS) ranging, which directly degrades the localization accuracy. It is necessary for a practical positioning algorithm to learn the specific of indoor ranging from statistics. Thus, we analyze the ranging characteristics based on real-world indoor experiments with both static and mobile cases, which...
When active anchors and agents conduct two-way time-of-arrival (TW-ToA) ranging, passive anchors can help active anchors to improve their localization accuracy. However, the range estimation at both active and passive anchors suffers from error due to clock imperfection. In this paper, we propose a new ranging protocol called two-way time-of-arrival with correction (TW-ToA-C), which can effectively...
We present and compare here solutions adapted to heterogeneous Wireless Body Area Networks (WBANs) to jointly fulfil indoor navigation and motion capture needs over large-scale trajectories. On-body devices are localized at the building scale by combining peer-to-peer range measurements over intra-WBAN links and further measurements with respect to external anchors forming the building infrastructure...
In this paper, we present a low complexity Time Of Arrival (TOA) estimator for direct-sequence ultra-wideband (DS-UWB) ranging system. With the assumption that TOA is the integer multiples of chip duration, our decoupled multiuser ranging (DEMR) estimator employs integrate-and-dump filter (IDF) in chip sampling rate instead of matched filter (MF) as the front-end to reduce sampling rate and to simplify...
Recent ESA research activities, within the GNSS Evolution Programme (GNSS EP) and within the General Study Programme (GSP), have investigated ground-to-space and space-to-space long-range cross-links techniques for accurate ranging and time-transfer [1] enabling, amongst a wide range of improvements, to place an accurate and significantly autonomous orbit and time determination function on-board a...
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