Accurate and robust indoor localization systems using ultra-wideband signals (original) (raw)
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Correcting non-line-of-sight path length estimation for ultra-wideband indoor localization
2015 International Conference on Location and GNSS (ICL-GNSS), 2015
Ultra-Wideband technology provides accurate localization in indoor environments using time-of-arrival based ranging techniques; however, the positioning accuracy is degraded by non-line-of-sight conditions. In this work, the relation between the non-line-of-sight path length error and the obstacles on the path from transmitter to receiver is used as input to a new positioning algorithm to correct the corrupted measurements. Simulation and experimental results demonstrate that the proposed algorithm provides a significant improvement in positioning accuracy as compared to line-of-sight algorithms.
Multipath-assisted maximum-likelihood indoor positioning using UWB signals
2014 IEEE International Conference on Communications Workshops (ICC), 2014
Multipath-assisted indoor positioning (using ultrawideband signals) exploits the geometric information contained in deterministic multipath components. With the help of a-priori available floorplan information, robust localization can be achieved, even in absence of a line-of-sight connection between anchor and agent. In a recent work, the Cramér-Rao lower bound has been derived for the position estimation variance using a channel model which explicitly takes into account diffuse multipath as a stochastic noise process in addition to the deterministic multipath components. In this paper, we adapt this model for position estimation via a measurement likelihood function and evaluate the performance for real channel measurements. Performance results confirm the applicability of this approach. A position accuracy better than 2.5 cm has been obtained in 90 % of the estimates using only one active anchor at a bandwidth of 2 GHz and robustness against non-line-of-sight situations has been demonstrated.
UWB for Robust Indoor Tracking: Weighting of Multipath Components for Efficient Estimation
IEEE Wireless Communications Letters, 2014
In a radio propagation channel, deterministic reflections carry important position-related information. With the help of prior knowledge such as a floor plan, this information can be exploited for indoor localization. This letter presents the improvement of a multipath-assisted tracking approach using information about the relevance of deterministic multipath components in an environment. This information is fed to a tracking filter as observation noise model. It is estimated from a few training signals between anchors and an agent at known positions. Tracking results are presented for measurements in a partial non-line-of-sight environment. At a bandwidth of 2 GHz, an accuracy of 4 cm can be achieved for over 90 % of the positions if additional channel information is available. Otherwise, this accuracy is only possible for about 45 % of the positions. The covariance of the estimation matches closely to the corresponding Cramèr-Rao Lower Bound.
Using Uwb Measurements for Statistical Analysis of the Ranging Error in Indoor Multipath Environment
International Journal on Wireless & Optical Communications, 2006
In this paper we use UWB measurements for bandwidths up to 3GHz to present a framework for statistical modeling of the indoor radio channel propagation characteristics that are pertinent to precise indoor geolocation using time-of-arrival (TOA) estimations. Accuracy of indoor geolocation systems relies on the strength and TOA of the direct path (DP) in the channel profile. Based on UWB measurements in a typical office building, we introduce empirical models for the path-loss and TOA of the DP. We use path-loss model for the DP to analyze the occurrence of the undetected direct path (UDP) conditions which cause large errors in indoor geolocation systems. Then we introduce a novel statistical model for the ranging or distance measurement error (DME) which is needed for comparative performance evaluation of the indoor positioning algorithms. The DME is a function of the bandwidth of the system, occurrence of the UDP conditions, and the distance between the transmitter and the receiver.
Identification of the Absence of Direct Path in Indoor Localization Systems
2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007
Ultra-wideband (UWB) indoor positioning systems based on time of arrival (ToA) techniques are considered to be the high precision alternatives to those employing received signal strength (RSS) or angle of arrival (AoA) due to their superior time-domain resolution. However, the performance of such systems may easily be degraded by the blockage of the direct path (DP) and occurrence of undetected direct path (UDP) condition. By erroneous detection of the other multipath components (MPCs) as DP, which is the indicator of the true distance between the transmitter and the receiver, substantial localization errors will be introduced into the system. Hence, detection of DP categorizes the receiver locations into two main classes of detected direct path (DDP) and undetected direct path (UDP). The real challenge is to be able to identify the class of the receiver location; therefore, to remedy the ranging measurement in UDP condition. In this paper we propose a methodology to identify and mitigate the UDP conditions, which can substantially improve the overall indoor positioning accuracy.
An Accurate Indoor Localization Approach Using UWB System
2020
Localization using ultra-wide band (UWB) signals gives accurate user position results for indoor localization. In UWB based indoor localization, the system transmits the UWB pulses from UWB tag to anchors. Accurate UWB pulse transmission in the UWB system determines the system’s localization performance. The indoor channel conditions, multipath effects and UWB signal blockage reduce the smooth transmission of the UWB pulses and affects the localization performance of the UWB system. The conventional UWB based localization systems use Gaussian pulse as the UWB pulse and these pulses are easily influenced by the indoor channel conditions. To overcome the localization challenges of the UWB system, we propose an indoor localization approach using second derivative of Gaussian pulses. The proposed second derivative of the Gaussian pulse-based approach reduces the ToA and localization errors and improves the localization performance of the UWB system. The simulation results show that the ...
Ultra Wideband Indoor Positioning Technologies: Analysis and Recent Advances
Sensors, 2016
In recent years, indoor positioning has emerged as a critical function in many end-user applications; including military, civilian, disaster relief and peacekeeping missions. In comparison with outdoor environments, sensing location information in indoor environments requires a higher precision and is a more challenging task in part because various objects reflect and disperse signals. Ultra WideBand (UWB) is an emerging technology in the field of indoor positioning that has shown better performance compared to others. In order to set the stage for this work, we provide a survey of the state-of-the-art technologies in indoor positioning, followed by a detailed comparative analysis of UWB positioning technologies. We also provide an analysis of strengths, weaknesses, opportunities, and threats (SWOT) to analyze the present state of UWB positioning technologies. While SWOT is not a quantitative approach, it helps in assessing the real status and in revealing the potential of UWB positioning to effectively address the indoor positioning problem. Unlike previous studies, this paper presents new taxonomies, reviews some major recent advances, and argues for further exploration by the research community of this challenging problem space.
Measurement and Modeling of Ultrawideband TOA-Based Ranging in Indoor Multipath Environments
IEEE Transactions on Vehicular Technology, 2009
In this paper, we present the results of the measurement and modeling of ultrawideband (UWB) time of arrival (TOA)-based ranging in different indoor multipath environments. We provide a detailed characterization of the spatial behavior of ranging, where we focus on the statistics of the ranging error in the presence and absence of the direct path (DP) and evaluate the path loss behavior in the former case, which is important for indoor geolocation coverage characterization. The frequencydomain measurements were conducted, with a nominal frequency of 4.5 GHz with two different bandwidths, i.e., 500 MHz and 3 GHz. The parameters of the ranging error probability distributions and path loss models are provided for different environments (e.g., an old office, a modern office, a house, and a manufacturing floor) and different ranging scenarios [e.g., indoor to indoor (ITI), outdoor to indoor (OTI), and roof to indoor (RTI)].
EURASIP Journal on Wireless Communications and Networking, 2008
Fine time resolution enables Ultra-Wideband (UWB) ranging systems to reliably extract the first multipath arrival corresponding to the range between a transmitter and receiver, even when attenuated in strength compared to later arrivals. Bearing systems alone lack any notion of time and in general select the arrival coinciding with the strongest path, which is rarely the first one in non line-of-sight conditions. Complementing UWB ranging systems with bearing capabilities allows indexing the arrivals as a function of both time and angle to isolate the first, providing precision range and angle. In order to gauge the limits of the joint UWB system, we carry out close to 20000 measurements up to 45 m in non line-of-sight conditions in four separate buildings with dominant wall material varying from sheet rock to steel. In addition, we report performance for varying bandwidth and center frequency of the system. Index Terms-Uniform circular array, frequency-invariant beamforming, spatial-temporal channel modeling This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the ICC 2008 proceedings.
A novel indoor localization scheme
2010 IEEE 12th International Conference on Communication Technology, 2010
Ultra-wideband (UWB) receivers can resolve individual multipath components (MPCs), due to the signal occupied a large bandwidths, so they are capable of accurately estimating the time of flight of the signal. To realize high-accuracy indoor localization, a novel UWB locating scheme through estimating the round trip time (RTT) of UWB signal is proposed. Each reference station (RS) transmits the baseband pulse modulated UWB signals. The signals are received by the user terminals (UT) and sent back to the original RS using a different carrier frequency. We can easily calculate the position of the UT by detecting the time gap between the feedback signal and the origin signal. Meanwhile, the multi-path detection algorithm for RTT estimation is presented and the localization performance of the proposed scheme is tested under IEEE 802.15.4a channel models. Experiments demonstrate that the proposed scheme can realize high accuracy localization with an error around the centimeter level.