Time Of Arrival Estimation Algorithm Research Articles

Frequency Domain Extended-MUSIC Algorithm for TOA Estimation in Indoor UWB Radio Impulse Channels

indoor localization systems have grown considerably, in order to obtain a high performance in dense multipath propagation channels. Many studies have been done in this area. Different methods have been proposed based on the use of Impulse Radio Ultra Wide band (IR-UWB) signals. These systems are usually based on time of arrival estimation using different algorithms. In this paper, a new time of arrival estimation algorithm is proposed for impulse radio UWB systems, which is based on the EXTENDED-MUSIC algorithm. Furthermore, Simulation results show these performances in multipath channels. The proposed method is compared with other high resolution algorithms such as Multiple SIGNAL Classification (MUSIC), estimation of signal parameters via rotational invariance technique (ESPRIT) and the MATRIX PENCIL method. Simulation will justify the high accuracy and resolution localization capabilities of the proposed algorithm. KeywordsRadio Ultra Wide band (IR-UWB), Time of arrival estimation (TOA), EXTENDED-MUSIC, ESPRIT, MATRIX PENCIL

Joint Estimation of TOA and DOA in IR-UWB System Using a Successive MUSIC Algorithm

Time-of-arrival (TOA) and direction-of-arrival (DOA) are key parameters in the impulse radio ultra wideband (IR-UWB) positioning system with a two-antennas receiver. A two-dimensional (2D) multiple signal classification (MUSIC) algorithm, which requires the 2D spectral peak search, can be used to estimate the parameters, but it has much higher computational complexity. This paper proposes a successive MUSIC algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak search. The proposed algorithm obtains the initial estimate of TOA corresponding to the first antenna via Root-MUSIC, and simplifies the 2D global search into successive one-dimensional searches to achieve the estimation of TOAs in the two antennas. It then estimates the DOA parameters via the difference of the TOAs between the two antennas. The proposed algorithm can get the parameters paired automatically, and has a much lower complexity than 2D-MUSIC algorithm. In addition, we have derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer---Rao bound of TOA and DOA estimation in the paper. The simulation results show that the parameter estimation performance of the proposed algorithm is better than that of Root-MUSIC, and is almost the same as that of 2D-MUSIC algorithm. Moreover, it has much better performance than matrix pencil algorithm, propagator method and estimation of signal parameters via rotational invariance techniques algorithm.

Yet another TOA estimation technique for IR-UWB

Purpose – The paper aims to propose a new method for estimating the time of arrival (TOA) of ultra-wideband (UWB) signals under IEEE 802.15.4a multipath channel model. Design/methodology/approach – The proposed approach is based on a proportionality test and consists in finding out whether two autoregressive (AR) processes, modeling two frames, are proportional or not. The latter operation uses a distance to measure the proportionality between the two AR processes. Findings – The developed technique may be used in two ways, sample-by-sample or block-by-block, according to the required ranging accuracy. It is important to note that the method offers flexibility between the computational load and the needed estimation accuracy. Moreover, the proposed method uses a threshold that is derived analytically according to a preset false alarm probability. Practical implications – Simulation experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the comparison is done against the well-known CLEAN algorithm for a sample-by-sample based TOA estimation and against three energy detector based receiver algorithms. The obtained results highlight the effectiveness of the developed approach. Originality/value – The developed TOA estimation algorithm is completely different from other techniques in the literature, and it is based on a proportionality test between two sliding frames. These latter are modeled by two AR processes. Then a distance measure is used to check whether or not the power spectral densities are proportional.

TOA Estimation Technique for IR-UWB Based on Homogeneity Test

This paper deals with the estimation of the time of arrival (TOA) of ultra-wideband signals under IEEE 802.15.4a channel models. The proposed approach is based on a randomness test and consists of determining whether an autoregressive (AR) process modeling an energy frame is random or not by using a distance to measure the randomness. The proposed method uses a threshold that is derived analytically according to a preset false alarm probability. To highlight the effectiveness of the developed approach, simulation setups as well as real data experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the proposed method is compared with the cell averaging constant false alarm rate technique, the threshold comparison algorithm, and the technique based on maximum energy selection with search back. The obtained results are promising, considering both simulations and collected real-life data.

An MLS-Prony implementation for a cm-Precise Super 10 m range 802.15.3c-PHY 60 GHz positioning application

A high-resolution time-of-arrival (ToA) estimation algorithm is applied to an IEEE 802.15.3c compatible signal package. The high speed multi-carrier mode of this 60 GHz super-Gbit/s wireless standard is promising for ToA due to its high bandwidth spec. The suitability of this multi-carrier mode for ToA purposes is first verified in a theoretical derivation. The ToA estimation algorithm itself consists of two estimation steps. The first, a coarse step, is based on an auto correlation operation. After this coarse step, a ToA refinement is performed on 10 OFDM payload packages. The method is based on the modified-least-squares-Prony method, a high resolution estimation technique, enabling a higher precision for the ToA estimate than is determined by the sampling period of the receiver. Thanks to the broadband spec of the 802.15.3c standard and the compactness of the algorithm, update rates of more than 200 kHz can be achieved. The algorithm enables tuning out frequency offset and channel multipath effects. cm-accuracy and precision is enabled at SNRs for distance values close to 10 m.

Packet-Reduced Ranging Method with Superresolution TOA Estimation Algorithm for Chirp-Based RTLS

In this paper, a packet-reduced ranging method using a superresolution time of arrival estimation algorithm for a chirp-based real-time locating system is presented. A variety of ranging methods, such as symmetric double-sided two-way ranging (SDS-TWR), have been proposed to remove the time drift due to the frequency offset using extra ranging packets. Our proposed method can perform robust ranging against the frequency offset using only two ranging packets while maintaining almost the same ranging accuracy as them. To verify the effectiveness of our proposed algorithm, the error performance of our proposed ranging method is analyzed and compared with others. The total ranging performance of TWR, SDS-TWR, and our proposed TWR are analyzed and verified through simulations in additive white Gaussian noise and multipath channels in the presence of the frequency offset.

Threshold Selection for Ultra-Wideband TOA Estimation based on Neural Networks

Because of the good penetration into many common materials and inherent fine resolution, Ultra-Wideband (UWB) signals are widely used in remote ranging and positioning applications. On the other hand, because of the high sampling rate, coherent Time of Arrival (TOA) estimation algorithms are not practical for low cost, low complexity UWB systems. In order to improve the precision of TOA estimation, an Energy Detection (ED) based non-coherent TOA estimation algorithm using Artificial Neural Networks (ANN) is presented which is based on the skewness after energy detection. The expected values of skewness and kurtosis with respect to the Signal to Noise Ratio (SNR) are investigated. It is shown that the skewness is more suitable for TOA estimation. The best threshold values for different SNRs are investigated and the effects of integration period and channel modes are examined. Comparisons with other ED based algorithms show that in CM1 and CM2 channels, the proposed algorithm provides higher precision and robustness in both high and low SNR environments.

Threshold Selection for TOA Estimation based on Skewness and Slope in Ultra-wideband Sensor Networks

Accurate localization has gained significant interest within sensor networks but because of the high sampling rate, Matched Filter (MF) based coherent Time of Arrival (TOA) estimation algorithms are not practical for low cost, low complexity Ultra-wideband (UWB) ranging, positioning and tracking systems. In this paper, an Energy Detection (ED) based non-coherent TOA estimation algorithm is presented where the TOA is estimated via Threshold Crossing (TC). The expected values of skewness, maximum slope, kurtosis and standard deviation with respect to the Signal to Noise Ratio (SNR) are investigated using the IEEE 802.15.4a Channel Models (CM). It is shown that the skewness and maximum slope are more sensitive to the SNR and thus more suitable for TOA estimation. To improve the precision of ED based TOA estimation, especially in low SNR environments, a new threshold selection algorithm is proposed which is based on a joint metric of the skewness and maximum slope. The best threshold values for different SNRs are investigated and the effects of integration period and channel models are examined. Comparisons with other ED based algorithms show that in both the CM1 and CM2 channels, the joint metric provides higher precision and robustness in both high and low SNR environments.

Efficient Time of Arrival Estimation Algorithm Achieving Maximum Likelihood Performance in Dense Multipath

Robust and accurate time-of-arrival (TOA) estimation in dense multipath channels such as those encountered in ultra-wideband (UWB) systems is a considerable challenge especially when the signal-to-noise ratio (SNR) is low. The exact maximum likelihood (EML) TOA estimator in dense multipath conditions has the potential to attain accurate TOA estimation, however, it is too complex for practical implementation. There is a substantial performance gap between the known practical algorithms for TOA estimation and the EML estimator. In this paper, a novel practical TOA estimation algorithm is developed that attains the EML performance when the multipath arrivals are dense. When the multipath arrivals density is low the estimator does not attain the maximum likelihood performance but still outperforms other known practical estimators. The estimator does not need to know the channel characteristics accurately, thus, it is robust to various multipath channels. The approach taken is to approximate the received multipath signal as a Gaussian process and derive the maximum likelihood estimator. In order to further decrease the computational load of the new algorithm, we develop a low complexity approximation with negligible performance degradation. The algorithm is useful for either single channel realization or multiple channel realizations using diversity either in time, frequency or space. When applying diversity technique a substantial performance gain is attained due to the optimal combining of the channel realizations and thus reliable TOA estimation is attainable even at low SNR. The estimator's performance can be closely predicted by a closed-form analytical error expression.

Finite-Resolution Digital Receiver for UWB TOA Estimation

In this paper, the effect of finite-resolution analog-to-digital converter (ADC) quantization on ultra-wideband (UWB) time of arrival (TOA) estimation is investigated. The deflection criterion is introduced for optimizing the nonuniform quantization. The training based TOA estimation algorithm using maximum likelihood (ML) rule is proposed. Compared with the full-resolution and energy-detection (ED) estimators via simulation, we demonstrate that our training based 3-level quantization scheme is satisfactory because it can approach a full-resolution estimator while decreasing the complexity greatly.

APPLICATION OF THE NEWTON METHOD TO IMPROVE THE ACCURACY OF TOA ESTIMATION WITH THE BEAMFORMING ALGORITHM AND THE MUSIC ALGORITHM

In this paper, a numerical method for improving the performance of the beamforming algorithm and the MUSIC algorithm for TOA (Time-of-arrival) estimation is presented. It has been shown that the conventional beamforming algorithm and the MUSIC algorithm can be used for time delay estimation. Using the beamforming algorithm and the MUSIC algorithm for TOA estimation, the initial estimate for the TOA is obtained. To improve the accuracy of the TOA estimation, we apply the Newton iteration to the initial estimate. The initial estimates obtained from the beamforming algorithm and the MUSIC algorithm are updated to obtain the flnal estimates which are more accurate than the initial estimates in terms of the RMSE (Root Mean Square Error). To flnd the TOA which maximizes the beamforming spectrum or the MUSIC spectrum, we flnd

A New Parameter Estimation Algorithm for Actual COSPAS-SARSAT Beacons

According to the high precision demand of estimating frequency of arrival (FOA) and time of arrival (TOA) in Galileo search and rescue (SAR) system, and considering the uncertainty of message bit width in actual received COSPAS-SARSAT beacons, a new FOA and TOA estimation algorithm which combines the Multiple Dimensions Joint Maximum Likelihood Estimation (MJMLE) algorithm and Barycenter calculation algorithm is proposed. The principle of the algorithm is derived and the concrete realization of the algorithm is given. Both Monte Carlo simulation and experimental results show that when CNR equals to the threshold of 34.8dBHz, root-mean- square errors (rmse) of FOA and TOA estimation in this algorithm are respectively within 0.03Hz and 9.5us, which are less than the system requirements of 0.05Hz and 11us. This algorithm has been applied to the Galileo Medium- altitude Earth Orbit Local User Terminal (MEOLUT station).

TOA estimation of UWB backscattering RFID tag with dual pulse modulation for clutter suppression

AbstractTo realize precise localization for UWB backscattering RFID system, the arrival time of the direct path in the received signal (referred as time of arrival (TOA)) needs to be accurately estimated. The background clutter is one of the major factors that deteriorates the TOA estimation accuracy in backscattering RFID system. To suppress the background clutter while maintain low‐complexity system design, we propose a novel UWB backscattering RFID system with its tag being implemented with dual pulse (DP) modulation. By transforming the mathematical model of received signal into a proper form, we discover the tag's sequence selection criteria which are able to mitigate the background clutter. For the proposed tag coded with dedicated sequences, a two‐stage TOA estimation algorithm able to effectively mitigate clutter is developed. Simulation results show that the proposed RFID system coupled with the algorithm is able to achieve accurate TOA estimation in the environment where the clutter overwhelms the tag response. Copyright © 2010 John Wiley & Sons, Ltd.

TOA Estimation Based on Match-Filtering Detection for UWB Wireless Sensor Networks

The TOA (time of arrival) estimation algorithms based on match-filtering detection for UWB (ultra wideband) wireless sensor networks are extensively studied in this paper. Based on the analysis of the drawbacks of the algorithms in the literature, a three-step algorithm is proposed: first, determine the search region for DP (direct path) detection; then, a rough detection of DP is made by threshold comparison; and last, the precise location of DP, i.e., the center of the arriving pulse, is obtained by a refined search process. The threshold factor used to calculate the threshold in the second step is set dynamically by using a model in terms of the kurtosis of the match-filtering output. The model is well independent of the channel model, and its effectiveness is proved through the comparison of the resulted performance with that of using fixed threshold factor. By comparing the performance of this algorithm with that of other algorithms, it can be observed that the proposed three-step algorithm has achieved a good trade-off between computational efficiency and estimation accuracy, thus more appropriate for current applications. In addition, the reliability of TOA estimation result is discussed through statistical analysis. Two levels of reliability are defined with regard to the corresponding kurtosis of the TOA estimation, and the probability density function for TOA estimation errors of each level is modeled. Properly incorporating the reliability information into the positioning algorithm will definitely improve the final location estimation accuracy.

Peak and leading edge detection for time-of-arrival estimation in band-limited positioning systems

The performance of the peak and leading edge detection methods for time-of-arrival (TOA) estimation in band-limited systems is examined. Analytical expressions for the detection performance in the presence of both random noise and multipath interference are derived. A dimensionless performance factor is presented that allows simple comparisons of the TOA estimation algorithms. These equations allow the performance tradeoff analysis to be undertaken without the need for simulations. It is shown that the leading edge detection method has significantly better multipath mitigation characteristics than the peak detection one, but at the expense of inferior noise performance.

Two-Step Time of Arrival Estimation for Pulse-Based Ultra-Wideband Systems

In cooperative localization systems, wireless nodes need to exchange accurate position-related information such as time-of-arrival (TOA) and angle-of-arrival (AOA), in order to obtain accurate location information. One alternative for providing accurate position-related information is to use ultra-wideband (UWB) signals. The high time resolution of UWB signals presents a potential for very accurate positioning based on TOA estimation. However, it is challenging to realize very accurate positioning systems in practical scenarios, due to both complexity/cost constraints and adverse channel conditions such as multipath propagation. In this paper, a two-step TOA estimation algorithm is proposed for UWB systems in order to provide accurate TOA estimation under practical constraints. In order to speed up the estimation process, the first step estimates a coarse TOA of the received signal based on received signal energy. Then, in the second step, the arrival time of the first signal path is estimated by considering a hypothesis testing approach. The proposed scheme uses low-rate correlation outputs and is able to perform accurate TOA estimation in reasonable time intervals. The simulation results are presented to analyze the performance of the estimator.

Analysis of Time of Arrival Estimation Using Wideband Measurements of Indoor Radio Propagations

Using time of arrival (TOA) to determine the distance between the transmitter and the receiver is the most popular technique for accurate indoor positioning. The accuracy of measuring the distance using this method is sensitive to the bandwidth of the system and the multipath condition between the wireless terminal and the access point. In general, as the bandwidth increases beyond a certain value, it is expected that the measured TOA error approaches zero. However, for the so-called undetected direct path (UDP) conditions, the system exhibits substantially high distance measurement errors that cannot be eliminated with the increase in the bandwidth of the system. In this paper, we provide an analysis of the behavior of superresolution and traditional TOA estimation algorithms in line-of-sight (LOS), non-LOS, and UDP conditions in indoor areas. The analysis is based on wideband frequency- domain measurements of the indoor radio channel propagations in several indoor areas, with special attention to the UDP conditions.

A Study on High Resolution Ranging Algorithm for The UWB Indoor Channel

In this paper, we present a novel and numerically efficient algorithm for high resolution TOA(Time Of Arrival) estimation under indoor radio propagation channels. The proposed algorithm is not dependent on the structure of receivers, i.e, it can be used with either coherent or non-coherent receivers. The TOA estimation algorithm is based on a high resolution frequency estimation algorithm of Minimum-norm The efficiency of the proposed algorithm relies on numerical analysis techniques in computing signal or noise subspaces. The algorithm is based on the two step procedures, one for transforming input data to frequency domain data and the other for estimating the unknown TOA using the proposed efficient algorithm. The efficiency in number of operations over other algorithms is presented. The performance of the proposed algorithm is investigated by means of computer simulations. Throughout the analytic and computer simulation results, we show that the proposed algorithm exhibits superior performance in estimating TOA estimation with limited computational cost.

A Two-Step TOA Estimation Method for UWB Based Wireless Sensor Networks

In order to design a low-calculation and high-precision TOA (time of arrival) estimation algorithm for UWB (ultra wideband) based wireless sensor network (WSN), a two-step TOA estimation method which jointly employs energy-detection (ED) and match-filtering (MF) is proposed in this paper. Based on analyzing the principles of the two-step method, it is pointed out that the success rate of DP (direct path) block detection in the first step and the setting of MF-threshold-factor in the second step are the key issues that affect the performance of the method. Algorithm selection of the first step and setting of the energy integration interval, which are the two factors that affect the success rate of DP block detection, are discussed through simulations. The idea of DMR (DP to minimum energy sample ratio) based MF-threshold-factor selection is proposed, and the mathematical model of the relationship between DMRs and the optimal MF-threshold-factors are built. Results show that the proposed two-step method greatly outperforms the one-step energy-detection based non-coherent method, while largely decreases the computational complexity compared to the one-step match-filtering based coherent method, so that the two-step method is more appropriate for application to sensor nodes which need to be designed with low