Accurate indoor wireless location with IR UWB systems a performance evaluation of joint receiver structures and TOA based mechanism (original) (raw)

Modeling of the TOA-based distance measurement error using UWB indoor radio measurements

2006

Time of Arrival (TOA) estimation used with ultra wideband (UWB) transmission is currently the most popular technique for accurate indoor geolocation. Due to severe indoor multipath conditions these techniques often suffer from significant inaccuracy in location estimation. In this paper we introduce a model for the error in estimated distance as measured from the estimated TOA of the direct path (DP) in a typical multipath indoor environment. The TOA estimation error has two components, (1) the errors caused by the multipath dispersion affecting any signal path and (2) the errors caused by undetected direct path (UDP) conditions. The statistical behavior of this error is also a function of the system bandwidth. The empirical data from UWB indoor measurements in an office building are used to design a model for the distance measurement error. This model relates the behavior of the two components of the TOA estimation error to the bandwidth of the system.

Performance evaluation of threshold-based TOA estimation techniques using IR-UWB indoor measurements

… Wireless, 2012. EW. …, 2012

Ultra-wide bandwidth (UWB) technology is a viable candidate for enabling accurate localization through time of arrival (TOA) based ranging techniques. These ranging techniques exploit the high time resolution of the UWB signals to estimate the TOA of the first signal path. Nevertheless, these techniques are facing the problem of proper multipath mitigation especially in harsh propagation environments in which the first path may not exist or it may not be the strongest. This paper presents a realistic comparison between the ranging performances of four threshold-based TOA estimation techniques using experimental data collected from an IR-UWB indoor propagation measurement campaign performed in an office building.

A Study of the Effects of Reference Point Density on Toa-Based UWB Indoor Positioning Systems

2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006

The performance of Ultra-Wideband (UWB) indoor positioning systems based on Time of Arrival (TOA) techniques is generally affected by the density of reference points (RPs), as well as undetected direct path (UDP) conditions. For a fixed number of reference points (RPs), the performance of some indoor positioning algorithms tends to degrade as the size of the area is increased, i.e. the RP density is decreased. In this paper, we evaluate the effects of RP density on the performance of different positioning algorithms in the presence of empirical distance measurement error (DME) models derived from UWB measurements in typical indoor environments. We then present functional relationships between RP density and positioning mean-square error (MSE) for these algorithms. These relationships can be used for more effective indoor positioning system design and deployment. Finally, we investigate the effects of bandwidth with respect to improving the performance of these algorithms.

An Experimental Evaluation of IEEE 802.15.4a Ultra Wide Band Technology for Precision Indoor Ranging

International Journal of Ambient Computing and Intelligence, 2012

Ultra Wide Band (UWB) wireless transmission has recently been the object of considerable attention in the field of next generation location aware wireless sensor networks (WSNs). This is due to its fine time resolution, energy efficiency and robustness to interference in harsh environments. This paper presents a thorough applied examination of prototype IEEE 802.15.4a impulse UWB transceiver technology to quantify the effect of line of sight (LOS) and non line of sight (NLOS) ranging in real indoor and outdoor environments. The results included draw on an extensive array of experiments that fully characterize the 802.15.4a UWB transceiver technology, its reliability and ranging capabilities for the first time. The goal of this work is to validate the technology as a dependable wireless communication mechanism for the subset of sensor network localization applications where reliability and precision positions are key concerns.

Impulse Radio UWB or Multicarrier UWB for Non-GPS Based Indoor Precise Positioning Systems

Navigation, 2008

The purpose of this paper is to investigate the use of Ultra Wideband (UWB) technology for indoor precise positioning systems that can be used by fire fighters. Two promising techniques to achieve indoor positioning accuracy of better than 1 m are Impulse Radio Ultra Wideband (IR-UWB) and Multicarrier Ultra Wideband (MC-UWB). This paper provides insight into key concepts such as receiver synchronization and practical system implementation for both these techniques from the positioning system perspective. This is followed by a system level comparison listing advantages and disadvantages of both these techniques. Basic simulation results comparing performance of a precise positioning system using IR-UWB and MC-UWB are presented, followed by indoor ranging test results using a MC-UWB based prototype. It is demonstrated that such an MC-UWB based positioning system achieves ranging accuracy of better than 1 m in indoor multipath environments without occupying GHz of bandwidth and without interfering with other existing wireless systems.

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)].

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 ...

A Low-Cost Ultra-Wideband Indoor Ranging System

IEEE Transactions on Instrumentation and Measurement, 2009

This paper presents the development of a low-cost indoor ranging technique based on time-of-arrival (TOA) estimation, using short-pulse ultra-wideband (UWB) signals. The realized system includes two identical UWB transceiver devices, in which the receiver section is based on a tunnel diode detector and the pulse generation is performed by a common bipolar transistor driven in avalanche mode. An indirect measurement of the distance between the devices is obtained by measuring the frequency of the generated pulse train. A theoretical model of the system is described, and a statistical analysis is presented, including the closed-form evaluation of the Cramér-Rao lower bound (CRLB) on the distance estimation and showing the asymptotic statistical efficiency of the proposed estimators. Furthermore, the principle of operation of the realized system prototypes is described, along with some implementation issues. Finally, experimental results are shown and discussed.

Ultra-wideband local positioning for smart home applications

2006

Due to the inherently fine temporal resolution of UWB, arriving multi-path components can be sharply timed at a receiver to provide accurate time of arrival estimates. This characteristic makes UWB ideal for high precision radiolocation applications. This paper focuses on feature UWB technology that makes it attractive for location precise. A Time-of-Arrival (TOA) based ranging scheme using UWB radio link is proposed. The problem of ToA estimation in multi path channels and sources of estimation error are discussed. Simulation results based on channel measurement data in indoor environment are presented. Results show that the accuracy enhancement depends on two principal factors: the strength of multipath components ep and the variance of non-line-of-sight (NLOS) delays ( eo).

Assessment of Direct Positioning for IR-UWB in IEEE 802.15.4a channels

2013 IEEE International Conference on Ultra-Wideband (ICUWB), 2013

This paper assesses the problem of localization in IR-UWB under realistic channel models for Direct Position Estimation (DPE) approaches. DPE schemes have been proposed for positioning and localization for well developed systems like GNSS, where it has been analytically proved that the Maximumlikelihood single-step estimator outperforms two-step procedures. The extension to wideband systems and less favorable scenarios like indoor UWB channels is less explored. We derive a DPE algorithm and analyze its performance against two-step TOA based localization for an IR-UWB system. Numerical results are provided for IEEE 802.15.4a channel model showing positioning performance of the two approaches and highlighting the tradeoffs.