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Localization and GNSS (ICL-GNSS), 2013 International Conference on

Date 25-27 June 2013

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  • [Front cover]

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    Freely Available from IEEE
  • [Copyright notice]

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    Freely Available from IEEE
  • GNSS space clocks: Performance analysis

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (366 KB) |  | HTML iconHTML  

    Atomic clocks are fundamental elements of a Global Navigation Satellite System (GNSS). Currently, several GNSSs are operational and the different clock technologies employed onboard their satellites benefit from the technological improvements achieved during the last decades. To ensure the timing capabilities needed for correct positioning, the analysis of GNSS clock performances is essential. We have recently started a performance analysis for GPS and GLONASS clocks, by using the satellite clock estimates produced by the Information-Analytical Centre (IAC) of the Russian Federal Space Agency. In this paper we discuss a few preliminary results of this analysis. We analyze the time deviation, frequency deviation, and frequency stability of the Cesium and Rubidium clocks onboard three GPS and GLONASS satellites. The obtained results highlight the presence of two common space clock anomalies, namely, deterministic oscillations and frequency jumps. Our final goal is to build a detailed statistics of the clock anomalies for all GNSSs. View full abstract»

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  • Design optimization for quantum communications in a GNSS intersatellite network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    We present the results of a feasibility study on the application of optical quantum communication links to a global navigation satellite system (GNSS) network with reference to the Galileo architecture. As a particularly relevant case, we derive specifications for an inter-satellite quantum key distribution (QKD) network and evaluate its expected performance in terms of achievable key lengths. View full abstract»

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  • Testing the test satellites: the Galileo IOV measurement accuracy

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    The European GNSS, Galileo, is currently in its In-Orbit Validation (IOV) phase where four satellites are finally available for computing the user position. In this phase, the analysis of the measurements obtained from the IOV satellites can provide insight on the performance and potentialities of the Galileo system. In this paper, a methodology based on the use of precise orbits and ionospheric corrections is suggested for the analysis of the Galileo IOV pseudorange and pseudorange rate errors. Several hours of data were collected using a Septentrio PolarRxS receiver and used to determine figures of merits such as RMS and maximum errors of the Galileo observables. From the analysis it emerges that Galileo measurements have accuracies comparable with those of GPS. The benefits of combined GPS-Galileo positioning are also highlighted and results relative to the computation of a Galileo-only navigation solution based on broadcast ephemerides are provided. View full abstract»

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  • A BeiDou hardware receiver based on the STA8088 chipset

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    The recent release, in December 2012, of the complete BeiDou B1I Interface Control Document has boosted new interest and R&D activities in the field. For a manufacturer of GNSS semiconductor devices, the first and logical step in the roadmap toward a full blown BeiDou receiver is the reuse of existing and proven silicon; the new product can blossom and reach the market more quickly, with good overall performance, though not yet optimized in every single aspect. Following this approach, the paper describes a BeiDou receiver implementation, based on the STA8088 “Teseo-II” consumer chip, which was originally designed for GPS, Galileo and GLONASS. Several technical solutions adopted in the receiver are disclosed, including aspects of the RF path, signal processing and higher level software algorithms like GEO velocity computation and ionosphere models. The main difficulty encountered was the generation of the B1I ranging codes, which was accomplished, with some performance trade-offs, by reusing the on-chip Galileo programmable code memory. The final result is a compact, consumer grade BeiDou hardware receiver, suitable for navigation and timing applications. Static positioning plots from real data, collected at a roof antenna are also reported. View full abstract»

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  • Recent results in receiving and decoding signals from the Beidou system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3514 KB) |  | HTML iconHTML  

    Since December 27, 2012, the Beidou Navigation Satellite System officially started to operate. This event is a great opportunity for researchers in South East of Asia to receive and analyze the Beidou signals. After the official statement, the researchers at NAVIS centre monitored the broadcasted signal by using NAVISOFT- our Software Radio Receiver. This paper shows the analysis on the navigation message that was broadcasted by the Beidou satellites on the B1I bandwidth. In general, we were able to observe a valid ephemeris data on visible satellites. The successful PVT computation by using combinations of GEO and MEO/IGSO in static condition through code-phase measurements is indicated in this paper. View full abstract»

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  • Deconvolution-based indoor localization with WLAN signals and unknown access point locations

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    In this paper, the problem of Received Signal Strength (RSS)-based WLAN positioning is newly formulated as a deconvolution problem and three deconvolution methods (namely Least Squares, Weighted Least Squares and Minimum Mean Square Error) are investigated with several RSS path loss models. The deconvolution approaches are compared with the fingerprinting approach in terms of performance and complexity. The main advantage of the deconvolution-based approaches versus the fingerprinting methods is the significant reduction in the size of the training database that need to be stored at the server side (and transferred to the mobile device) for the WLAN-based positioning. We will show that the deconvolution based estimation can decrease of the order of ten times the size of the training database, while still being able to achieve comparable root mean square errors in the distance estimation. View full abstract»

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  • Analysis of hybrid and cooperative positioning algorithms in urban canyon scenarios

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    Dense urban areas are particularly challenging environments for global navigation satellite systems (GNSS) because the satellite visibility is heavily reduced due to the presence of the so called urban canyons, composed of a series of tall buildings and narrow streets. In order to improve GNSS performance in these environments, hybrid (GNSS/terrestrial) and cooperative positioning algorithms that combine pseudorange measurements from visible satellites and terrestrial range measurements from neighboring terrestrial receivers have been recently proposed in the literature. Mainly, these algorithms have been tested in static or pedestrian mobility scenarios. This paper, first introduces a robust procedure that selects the most reliable neighbors for cooperation and then analyzes the performance of the optimized hybrid and cooperative positioning algorithms in a typical urban canyon scenario for vehicular navigations. Simulation results demonstrate that the positioning algorithms can accurately track the movement of vehicles in urban canyons even without fixed terrestrial infrastructure. Moreover, an accurate complexity analysis of the different hybrid algorithms is presented to understand their suitability for a real implementation. View full abstract»

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  • DVB-T positioning with a one shot receiver

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (215 KB) |  | HTML iconHTML  

    In this paper a one shot receiver for DVB-T positioning is presented. DVB-T SFN signals can be used as Signals-of-Opportunity in urban environment to assist GNSS in case the GNSS-only positioning shows degraded performance. The normal mechanism of DVB-T positioning involves a tracking stage to refine the coarse delay estimation obtained by the acquisition stage. However due to the high SNR of DVB-T signals, the delay estimation can be refined by some simple interpolation methods with lower complexity and power consumption. Two different interpolation methods, linear interpolation and sinc interpolation, are analysed in the paper. Simulation results show that the one shot receiver proposed in this paper behaves as a tracking-based receiver, but exhibits a lower complexity. View full abstract»

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  • Real-time RFID localization using RSS

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (354 KB) |  | HTML iconHTML  

    New computing paradigms have underscored the need to locate objects in an environment, motivating several object localization approaches targeting competing technologies and specific applications. While RFID technology recently emerged as a viable platform for locating objects, several unresolved key challenges precluded higher performance and wider applicability. We present an RFID-based real-time location system that uses Received Signal Strength (RSS) to better model the distance-decaying behavior of radio signals in an orientation-agnostic manner.We experimentally leverage the proposed robust models to simultaneously locate several stationary and mobile objects tagged with passive tags in a realistically noisy indoor environment, with an average accuracy of 0.6 meters. A more general conclusion of this work is that contrary to common belief, RSS can indeed serve as reliable metric for a variety of select applications, including localization. View full abstract»

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  • Code smoothing for BOC ambiguity mitigation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (546 KB) |  | HTML iconHTML  

    The most recent generation of Global Navigation Satellite Systems (GNSS) are implementing Binary Offset Carrier (BOC) modulation. These signals are expected to provide not only better precision in the estimation of the signal's delay and phase but also more robustness to multipath effects. The advantage of BOC signals is that the main lobe of the correlation is very narrow, but on the other hand they present side lobes. For high-order signals, the amplitude of the side lobes can be similar to the amplitude of the main one or even exceed it under specific scenarios. Some techniques to mitigate the code ambiguity exploit the fact that BOC signals can be understood as the sum of two BPSK signals. Even though these techniques achieve their objective, they lose the robustness against multipath and increase the tracking noise. This paper presents a new combination between the time delay estimated by these kind of techniques and the time delay estimated using the full BOC. The idea of the combination is the same as the carrier smoothing but instead of using the carrier measurement, two code measurements are combined. Since the delay introduced by the ionosphere is the same, or very close, using the Full-BOC and the two-BPSK techniques, as it will be shown in this paper, the smoothing time can be large values, compared with the common carrier smoothing time. Several simulations of the new code smoothing strategy for different scenarios are presented in this paper. View full abstract»

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  • Modified parallel code-phase search for acquisition in presence of sign transition

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (251 KB) |  | HTML iconHTML  

    One of the method to have a fast acquisition of GNSS signals is the parallel code-phase search, which uses the fast Fourier transform (FFT) to perform the correlation. A problem with this method is the potential sign transition that can happen between two code periods due to data or secondary code and lead to a loss of sensitivity or to the non-detection of the signal. A known straightforward solution consists in using two code periods instead of one for the correlation. However, in addition to increasing the complexity, this solution is not efficient since half of the points calculated are discarded. This led us to look for a more efficient algorithm. The algorithm proposed in this article transforms the initial correlation into two smaller correlations. When the radix-2 FFT is used, the proposed algorithm is more efficient for half of the possible sampling frequencies. It is shown for example that the theoretical number of operations can be reduced by about 21 %, and that the memory resources for an FPGA implementation can be almost halved. View full abstract»

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  • Code and frequency estimation in Galileo mass market receivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    Mass market receivers feature particular signal processing techniques, to comply with mobile and consumer devices resources and requirements. Delay and frequency estimation algorithms have then been redefined or adapted, in particular to cope with the new Galileo OS signals. The scope of the work is the analysis, development and performance examination of some of the main GNSS acquisition and tracking algorithms currently used in mass market receivers. The feasibility of such techniques is proved by means of semi-analytical and Monte Carlo simulations, outlining the estimators sensitivity and accuracy, and by tests on real Galileo IOV signals. View full abstract»

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  • MULTI-GNSS receivers/IMU system aimed at the design of a heading-constrained Tightly-Coupled algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (758 KB) |  | HTML iconHTML  

    This paper presents the design of a truly low-cost multi-GNSS receivers /IMU navigation system that exploits the benefits of GNSS technology in attitude determination. The sensor package of the system consists of 4 single chipset receivers, 4 antennas, and one low grade MEMS IMU. Both parts, the GNSS and the IMU ones, are integrated by following a heading-constrained Tightly-Coupled approach, where inertial and GNSS raw measurements as well as GNSS computed heading are blended into an Extended Kalman Filter. To compute the attitude solution based on GNSS carrier phase measurements an integer ambiguity resolution algorithm has been developed, which takes advantage of the a priori solution of the EKF to reduce the search space and to provide an on-the-fly solution. The heading-constrained Tightly-Coupled approach followed in this paper has shown superior attitude accuracies when compared to the regular Tightly-Coupled implementation. View full abstract»

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  • Performance assessment of wavelet based techniques in mitigating narrow-band interference

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    New Global Navigation Satellite Systems (GNSS) in addition to the current American Global Positioning System (GPS) and the Russian GLONASS are being developed leading the GNSS world towards a new era where a wider plethora of services and signals will be available for the end user. The majority of such services needs high accuracy and reliability provided by the navigational interoperable systems. However, intentional and unintentional interference represent one of the main causes of accuracy degradation, and as a consequence, they are a threat to GNSS based application. This paper focuses on a performance assessment of an innovative interference mitigation algorithm based on the use of the wavelet transform, targeting narrow-band interference. The paper will assess the capability of the representation in the time-scale domain to split the interference component and the useful signal thus allowing for a removal of most of the interfering power. Performance are assessed with respect to the interference bandwidth and carrier frequency offset, the number of decomposition levels and the effect of different wavelet families. View full abstract»

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  • Jammer impact on Galileo and GPS receivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    Global Navigation Satellite Systems (GNSSs) are vulnerable to several threats including jamming and spoofing. Jamming is the deliberate transmission of powerful Radio-Frequency (RF) signals which can easily overpower the much weaker GNSS components disturbing and, in some cases, denying GNSS operations. In recent years an increasing number of cheap, though illegal, jammers have become commercially available. In this paper, the impact of these jammers on Global Positioning System (GPS) and Galileo L1/E1 signal reception is investigated. It is shown that the signals of each system are affected in similar ways and this is due to the wide-band nature of the jamming signals. Narrow-band receivers are less impacted by jamming since they are able to filter out a greater portion of the interfering signal. Interestingly, the presence of a pure pilot channel in the Galileo E1 modulation allows receivers to use a pure Phase Lock Loop (PLL) which in turn allows signal reception in the presence of stronger jamming signals with respect to the GPS L1 C/A case. View full abstract»

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  • Frequency-domain code replica detection for a GNSS receiver

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    This paper addresses the problem of detecting the presence of spreading signal replica in GNSS receivers, a problem that is often related to the presence of non-authentic GNSS signals. In order to carry out the detection process, a super-resolution frequency-domain technique is proposed based on the well-known Pisarenko harmonic decomposition, which allows us to circumvent many of the problems encountered by non-parametric spectral methods in the presence of short data records. The proposed technique allows to detect the presence of signal replicas while at the same time, it provides an estimate of its frequencies which can be used for frequency tracking purposes in integrity monitoring applications. The performance of the proposed technique has been tested with real GNSS signals from a hardware simulator, confirming the capability of this technique to detect real-life code replicas, even when they are just a few Hz apart. View full abstract»

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  • Statistical test applied to detect distortions of GNSS signals

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (231 KB) |  | HTML iconHTML  

    The extremely low power of Global Navigation Satellite System (GNSS) signals makes them vulnerable to disturbances and interference from external sources. These induce distortions on the correlation function that reflect upon a degraded pseudoranges measurement and poor positioning accuracy. On the other hand, the wide spread use of GNSS receivers in critical applications demands for improved performance in terms of positioning accuracy and integrity. This paper proposes a new algorithm based on the statistical testing of post-correlation measurements to detect signal distortions and to prevent degradations in the receiver positioning performance. The application of statistical tests to GNSS is not yet deeply investigated, but some recent works already show good performance when Goodness of Fit (GoF) tests are applied to raw signal samples to detect interference. The paper presents a quality monitoring algorithm, based on the application of a statistical testing, known as sign test, applied to the post correlation stage of a GNSS receiver. Promising results are obtained to detect distortions in the correlation shape, for two different harsh environments, i.e., with the presence of interference sources and under a spoofing attack. The main advantages of the proposed method are the low complexity, the indipendence from the type of disturbance and the possibility of its application to any GNSS modulation. View full abstract»

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  • Signal quality checks for multipath detection in GNSS

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (541 KB) |  | HTML iconHTML  

    In GNSS, one of the most important degradations in the signal is caused by the multipath effect, which introduces a bias that impacts the user's position accuracy. The multipath components are attenuated and delayed versions of the transmitted signal, and they are produced by reflections on different obstacles or objects. The aim of this paper is to analyze and compare two multipath detection techniques, namely the Slope Asymmetry Metric (SAM) and the C/N0 evolution, as possible tools to check the quality of the signal in different scenarios. It is shown that while both techniques can provide information about the presence of multipath, the SAM is in general more sensitivity to this effect. View full abstract»

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  • Impact of the group delay on BOC(M,N) tracking: Potential filter issues in robust side-lobe switching for high-order BOC modulations

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    This paper discusses some technical problems and proposes a solution related to the implementation of a robust switching between single-side and double-side lobe tracking modes in case of BOC modulated signals, in particular BOC(M,N), with M, N > 1. It is demonstrated that typical group delay distortions due to wide-band front-end filters can potentially lead to code tracking biases, increasing the risk of false locks and degrading the performance of the BOC tracking loops. These effects represent also a potential problem for the coexistence of the side-lobe switching functionality with other advanced algorithms in professional-grade GNSS receivers. These practical issues are investigated and a possible solution is demonstrated by means of simulation results, considering the BOC(M,N) modulations in the Galileo E1a and E6a bandwidths. View full abstract»

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  • Localization of unknown indoor wireless transmitter

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    Many management tasks, for instance optimizing placement of a new Wi-Fi or femtocell access points (AP), or detecting unauthorized transmitter (Tx), requires the ability to locate individual Tx inside buildings. Available techniques to locate Txs require extensive war driving measurements and significant computations, or complex and additional hardware. This paper presents a time-efficient method, based on only collected received signal strength (RSS) data to estimate the location of unknown Tx installed inside a multi-storey building. Three-stage algorithm is proposed. Firstly, the building's location from which the signal is transmitted from, is defined on the area map. Secondly, the floor level of the determined building on which the unknown Tx is installed, is determined. Finally, 2-dimensional location coordinates of Tx and the path loss parameters are jointly estimated. The method is evaluated using realistic simulated data obtained from iBuildNet® wireless network design and optimization tool developed by Ranplan. The simulation results confirm that developed algorithm works accurately and is especially helpful to locate an unknown Tx in changing and unknown environments. View full abstract»

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  • Two-step hybrid self-localization using unsynchronized low-complexity anchors

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    Self-localization using unsynchronized low-complexity anchors has a number of attractive features. Traditional self-localization techniques are not suitable to this scenario or have their applicability limitations. In this paper, a two-step hybrid self-localization technique using unsynchronized low-complexity anchors is proposed, which can achieve two-dimensional (2-D) instantaneous localization for both mobile and fixed agents and eliminate the need for heading information of the agents. In the first step, an initial location estimate is obtained utilizing range information based on received-signal-strength (RSS) measurements. In the second step, differential angle-of-arrival (AOA) measurements are converted to range measurements with the aid of the first step location estimate. Finally, a two-step hybrid localization algorithm is obtained using all the measurements in the first step and the second step. Simulation results show that the two-step hybrid self-localization technique has relatively high accuracy even in the scenarios with large RSS-based ranging variances and medium AOA measurement variances. View full abstract»

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  • Swarm exploration and navigation on mars

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    We propose autonomous robotic swarm exploration to search for extra-terrestrial life in the Valles Marineris canyon system on Mars. The swarm consists of unmanned ground vehicles (UGVs) and unmanned aerial vehicles (UAVs). Key technologies are robust flight and swarm control algorithms as well as infrastructure-less swarm navigation. The swarm navigation uses inertial navigation, laser scanners, cameras, and relative radio positioning systems. The later one employs hybrid time-division multiple access (TDMA) - frequency division multiple access (FDMA) and interleaved round-trip delay ranging measurements. For TDMA, an autonomous distributed slot synchronization algorithm is presented.We present a swarm scenario with initially ten elements, adding one element after 6.25 s, until 25 elements are active. The synchronization algorithm is stable transmitting only five out of eight possible symbols per TDMA slot for 25 swarm elements, but is only stable for 17 swarm elements transmitting all eight symbols per slot. Nevertheless, a distributed swarm navigation particle filter achieves an accuracy of 1m or better for 21 swarm elements in the later case. View full abstract»

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  • Ranging results using a UWB platform in an indoor environment

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    This paper presents an impulse-radio UWB experimental platform for ranging and positioning in GNSS-challenged environments. The platform is based on the two-way time-of-arrival principle of operation, which reduces architecture complexity and relaxes the synchronization requirements with respect to time-of-arrival or time-difference-of-arrival solutions. The modular architecture of the platform is described together with the design and features of its main components, namely the 5.6-GHz RF front end and the baseband module for measurement and processing. A set of experimental results obtained using the realized platform in an indoor office environment is presented and discussed. The platform provides a maximum range of about 30 m in line-of-sight conditions with an RMSE of the order of 40 cm. View full abstract»

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