scholarly journals Experimental Evaluation of Multipath Mitigation in TDOA-Based Indoor Passive Localization System Using A Beam Steering Broadband Circular Polarization Antenna

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 362 ◽  
Author(s):  
Changjiang Su ◽  
Yanqun Liu ◽  
Leilei Liu ◽  
Mei Yang ◽  
Hongxin Zhao ◽  
...  
Keyword(s):  
Circular Polarization ◽  
Experimental Evaluation ◽  
Multipath Propagation ◽  
Beam Steering ◽  
Line Of Sight ◽  
Indoor Environments ◽  
Rf Switch ◽  
Multipath Mitigation ◽  
Localization System ◽  
Passive Localization

An experimental evaluation of multipath mitigation using a beam steering broadband circular polarization antenna (BSBCPA) in indoor passive localization system based on time differences of arrival (TDOA) is presented in this paper. The BSBCPA consists of a beam switch network, four identical hexagon patch elements and their respective feeding networks. By controlling the states of a radio frequency (RF) switch in the beam switch network, four steering circular polarization beams can be excited separately for azimuth omnidirectional coverage. Combining the spatial selectivity of steering beams and circular polarization in the BSBCPA, the positioning inaccuracy from indoor multipath propagation can be mitigated. In two different indoor environments with line of sight (LOS), complex multipath, when transmitting a 20 MHz bandwidth signal in WLAN, the 2D positioning mean error obtained is 0.7 m and 0.82 m, respectively. Compared with conventional omnidirectional linear polarization antenna (OLPA), the BSBCPA can at least improve positioning accuracy by 51%. The experimental results show that the proposed BSBCPA can significantly mitigate multipath propagation for TDOA-based indoor passive localization.

scholarly journals Proposal for a Localization System for an IoT Ecosystem

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 3016
Author(s):  
Juraj Machaj ◽  
Peter Brida ◽  
Slavomir Matuska
Keyword(s):  
Service Providers ◽  
Inertial Sensors ◽  
Multipath Propagation ◽  
Dead Reckoning ◽  
Global Navigation Satellite Systems ◽  
High Signal ◽  
Indoor Environments ◽  
Localization System ◽  
Battery Capacity ◽  
Iot Devices

In the last decade, positioning using wireless signals has gained a lot of attention since it could open new opportunities for service providers. Localization is important, especially in indoor environments, where the widely used global navigation satellite systems (GNSS) signals suffer from high signal attenuation and multipath propagation, resulting in poor accuracy or a loss of positioning service. Moreover, in an Internet of things (IoT) environment, the implementation of GNSS receivers into devices may result in higher demands on battery capacity, as well as increased cost of the hardware itself. Therefore, alternative localization systems that are based on wireless signals for the communication of IoT devices are gaining a lot of attention. In this paper, we provide a design of an IoT localization system, which consists of multiple localization modules that can be utilized for the positioning of IoT devices that are connected thru various wireless technologies. The proposed system can currently perform localization based on received signals from LoRaWAN, ZigBee, Wi-Fi, UWB and cellular technologies. The implemented pedestrian dead reckoning algorithm can process the data measured by a mobile device that is equipped with inertial sensors to construct a radio map and thus help with the deployment of the positioning services based on a fingerprinting approach.

Dynamic multipath mitigation applying unscented Kalman filters in local positioning systems

2011 ◽  
Vol 3 (3) ◽  
pp. 365-372 ◽  
Author(s):  
Thorsten Nowak ◽  
Andreas Eidloth
Keyword(s):  
Kalman Filters ◽  
Multipath Propagation ◽  
Time Of Arrival ◽  
Indoor Environments ◽  
Multipath Mitigation ◽  
Positioning Systems ◽  
Channel Dynamics ◽  
Outdoor Environments ◽  
Sequential Bayesian Estimation

Multipath propagation is still one of the major problems in local positioning systems today. Especially in indoor environments, the received signals are disturbed by blockages and reflections. This can lead to a large bias in the user's time-of-arrival (TOA) value. Thus multipath is the most dominant error source for positioning. In order to improve the positioning performance in multipath environments, recent multipath mitigation algorithms based upon the concept of sequential Bayesian estimation are used. The presented approach tries to overcome the multipath problem by estimating the channel dynamics, using unscented Kalman filters (UKF). Simulations on artificial and measured channels from indoor as well as outdoor environments show the profit of the proposed estimator model. Furthermore, the quality of channel estimation applying the UKF and the channel sounding capabilities of the estimator are shown.

scholarly journals A design study on complexity reduced multipath mitigation

2012 ◽  
Vol 10 ◽  
pp. 167-173 ◽  
Author(s):  
U. Wasenmüller ◽  
T. Brack ◽  
I. Groh ◽  
E. Staudinger ◽  
S. Sand ◽  
...  
Keyword(s):  
Design Space Exploration ◽  
Multipath Propagation ◽  
Signal Propagation ◽  
Global Navigation Satellite Systems ◽  
Superior Performance ◽  
Line Of Sight ◽  
Time Signal ◽  
Navigation Systems ◽  
Design Study ◽  
Multipath Mitigation

Abstract. Global navigation satellite systems, e.g. the current GPS and the future European Galileo system, are frequently used in car navigation systems or smart phones to determine the position of a user. The calculation of the mobile position is based on the signal propagation times between the satellites and the mobile terminal. At least four time of arrival (TOA) measurements from four different satellites are required to resolve the position uniquely. Further, the satellites need to be line-of-sight to the receiver for exact position calculation. However, in an urban area, the direct path may be blocked and the resulting multipath propagation causes errors in the order of tens of meters for each measurement. and in the case of non-line-of-sight (NLOS), positive errors in the order of hundreds of meters. In this paper an advanced algorithm for multipath mitigation known as CRMM is presented. CRMM features reduced algorithmic complexity and superior performance in comparison with other state of the art multipath mitigation algorithms. Simulation results demonstrate the significant improvements in position calculation in environments with severe multipath propagation. Nevertheless, in relation to traditional algorithms an increased effort is required for real-time signal processing due to the large amount of data, which has to be processed in parallel. Based on CRMM, we performed a comprehensive design study including a design space exploration for the tracking unit hardware part, and prototype implementation for hardware complexity estimation.

scholarly journals RMLNet—A Reliable Wireless Network for a Multiarea TDOA-Based Localization System

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4374
Author(s):  
Yuan Xue ◽  
Wei Su ◽  
Dong Yang ◽  
Hongchao Wang ◽  
Weiting Zhang
Keyword(s):  
Multipath Propagation ◽  
High Rate ◽  
Target Area ◽  
Indoor Environments ◽  
Localization Algorithm ◽  
Mobile Nodes ◽  
Target Node ◽  
Position Information ◽  
Precise Position ◽  
Localization System

Ultrawideband (UWB) wireless communication is a promising spread-spectrum technology for accurate localization among devices characterized by a low transmission power, a high rate and immunity to multipath propagation. The accurately of the clock synchronization algorithm and the time-difference-of-arrival (TDOA) localization algorithm provide precise position information of mobile nodes with centimeter-level accuracy for the UWB localization system. However, the reliability of target node localization for multi-area localization remains a subject of research. Especially for dynamic and harsh indoor environments, an effective scheme among competing target nodes for localization due to the scarcity of radio resources remains a challenge. In this paper, we present RMLNet, an approach focus on the medium access control (MAC) layer, which guarantees general localization application reliability on multi-area localization. Specifically, the design requires specific and optimized solutions for managing and coordinating multiple anchor nodes. In addition, an approach for target area determination is proposed, which can approximately determine the region of the target node by the received signal strength indication (RSSI), to support RMLNet. Furthermore, we implement the system to estimate the localization of the target node and evaluate its performance in practice. Experiments and simulations show that RMLNet can achieve localization application reliability multi-area localization with a better localization performance of competing target nodes.

scholarly journals ES-DPR: A DOA-Based Method for Passive Localization in Indoor Environments

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2482 ◽  
Author(s):  
Zhang Chen ◽  
Jinlong Wang
Keyword(s):  
Multipath Propagation ◽  
Estimation Algorithm ◽  
Doa Estimation ◽  
Recognition Algorithm ◽  
Indoor Environments ◽  
Direct Path ◽  
Multipath Signals ◽  
Localization Approach ◽  
Passive Localization ◽  
Methods Numerical

In this paper, we propose a novel indoor passive localization approach called eigenspace-based DOA with direct-path recognition (ES-DPR), based on a DOA estimation algorithm with multiple omnidirectional antennas deployed in a uniform linear array (ULA). To address the multipath propagation interference problem in the indoor environments, we utilize the azimuth and RSS estimation results, which are calculated by using the eigenspace-based DOA (ES-DOA) algorithm, in a novel style. A direct-path bearing recognition algorithm is introduced to identify the real DOA of the signal source in different indoor environments, by combining the azimuth and RSS estimation with ensemble learning methods. Numerical simulations are conducted to verify the validity and superiority of the proposed method. The results show that the proposed ES-DPR method can achieve high resolution and has strong anti-noise capability in dealing with the multipath signals, and the direct-path recognition algorithm is reliable and robust in different indoor environments, even in undetectable direct-path conditions.

Wi-Fi Fine Time Measurement: Data Analysis and Processing for Indoor Localisation

2020 ◽  
Vol 73 (5) ◽  
pp. 1106-1128 ◽  
Author(s):  
Yue Yu ◽  
Ruizhi Chen ◽  
Zuoya Liu ◽  
Guangyi Guo ◽  
Feng Ye ◽  
...  
Keyword(s):  
Multipath Propagation ◽  
Low Cost ◽  
Measurement Data ◽  
Time Measurement ◽  
Location Based Services ◽  
Line Of Sight ◽  
Indoor Environments ◽  
Positioning Systems ◽  
Indoor Localisation ◽  
Fine Time

Indoor positioning systems have received increasing attention for supporting location-based services in indoor environments. Wi-Fi based indoor localisation has become attractive due to its extensive distribution and low cost properties. IEEE 802.11-2016 now includes a Wi-Fi Fine Time Measurement (FTM) protocol which can be used for Wi-Fi ranging between intelligent terminal and Wi-Fi access point. This paper introduces a framework of Wi-Fi FTM data acquisition and processing that can be used for indoor localisation. We analyse the main factors that affect the accuracy of Wi-Fi ranging and propose a calibration, filtering and modelling algorithm that can effectively reduce the ranging error caused by clock deviation, non-line-of-sight (NLOS) and multipath propagation. Experimental results show that the proposed calibration and filtering method is able to achieve metre-level ranging accuracy in case of line-of-sight by using large bandwidth. Estimation results also show that the proposed Wi-Fi ranging model provides an accurate ranging performance in NLOS and multipath contained indoor environment; the final positioning error is less than 2·2 m with a stable output frequency of 3 Hz.

scholarly journals Broadband Linear Polarization in Ap Stars

1993 ◽  
Vol 138 ◽  
pp. 305-309
Author(s):  
Marco Landolfi ◽  
Egidio Landi Degl’Innocenti ◽  
Maurizio Landi Degl’Innocenti ◽  
Jean-Louis Leroy ◽  
Stefano Bagnulo
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Linear Polarization ◽  
Rotation Axis ◽  
Spectral Lines ◽  
Line Of Sight ◽  
Long Time ◽  
Rotating Star ◽  
Ap Stars ◽  
The Magnetic Field

AbstractBroadband linear polarization in the spectra of Ap stars is believed to be due to differential saturation between σ and π Zeeman components in spectral lines. This mechanism has been known for a long time to be the main agent of a similar phenomenon observed in sunspots. Since this phenomenon has been carefully calibrated in the solar case, it can be confidently used to deduce the magnetic field of Ap stars.Given the magnetic configuration of a rotating star, it is possible to deduce the broadband polarization at any phase. Calculations performed for the oblique dipole model show that the resulting polarization diagrams are very sensitive to the values of i (the angle between the rotation axis and the line of sight) and β (the angle between the rotation and magnetic axes). The dependence on i and β is such that the four-fold ambiguity typical of the circular polarization observations ((i,β), (β,i), (π-i,π-β), (π-β,π-i)) can be removed.

Multipath propagation model for line-of-sight street microcells in urban area

2000 ◽  
Vol 49 (2) ◽  
pp. 422-427 ◽  
Author(s):  
S. Ichitsubo ◽  
T. Furuno ◽  
T. Taga ◽  
R. Kawasaki
Keyword(s):  
Urban Area ◽  
Multipath Propagation ◽  
Propagation Model ◽  
Line Of Sight

Ultra-Wideband-Based Localization for Quadcopter Navigation

2016 ◽  
Vol 04 (01) ◽  
pp. 23-34 ◽  
Author(s):  
Kexin Guo ◽  
Zhirong Qiu ◽  
Cunxiao Miao ◽  
Abdul Hanif Zaini ◽  
Chun-Lin Chen ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Global Positioning System ◽  
Ultra Wideband ◽  
Line Of Sight ◽  
Positioning System ◽  
Localization Algorithm ◽  
Control Loop ◽  
Flight Tests ◽  
Localization System ◽  
Global Positioning

Micro unmanned aerial vehicles (UAVs) are promising to play more and more important roles in both civilian and military activities. Currently, the navigation of UAVs is critically dependent on the localization service provided by the Global Positioning System (GPS), which suffers from the multipath effect and blockage of line-of-sight, and fails to work in an indoor, forest or urban environment. In this paper, we establish a localization system for quadcopters based on ultra-wideband (UWB) range measurements. To achieve the localization, a UWB module is installed on the quadcopter to actively send ranging requests to some fixed UWB modules at known positions (anchors). Once a distance is obtained, it is calibrated first and then goes through outlier detection before being fed to a localization algorithm. The localization algorithm is initialized by trilateration and sustained by the extended Kalman filter (EKF). The position and velocity estimates produced by the algorithm will be further fed to the control loop to aid the navigation of the quadcopter. Various flight tests in different environments have been conducted to validate the performance of UWB ranging and localization algorithm.

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