Ultra-Wide Band (UWB)- Localization

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N-TWR: An Accurate Time-of-flight-based N-ary Ranging Protocol for Ultra-Wide Band

N-TWR: An Accurate Time-of-flight-based N-ary Ranging Protocol for Ultra-Wide Band

Thanks to the broadcast of the START message, N-TWR reduces the number of messages needed to poll n anchors. By using N- TWR, the whole ranging process is completed in a shorter time than classical ranging protocols, typically few milliseconds, de- pending on the number of anchors. This duration is consistent with usual duty cycles values considered in WSNs: for a ranging period of one second, the duty cycle is lower than 1%. The message num- ber reduction, combined with the limited range of UWB transmis- sion, has another benefit: it offers good scalability properties to N-TWR. Only a limited number of anchors will receive the initial START message and participate to the localization operation. This localization operation only lasts a couple of milliseconds. As such, it is reasonable to think that several target nodes could request for localization with N-TWR. However, how to orchestrate several localization requests concurrently is not investigated in this paper and is kept for future works.
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An Original Correction Method for Indoor Ultra Wide Band Ranging-based Localisation System

An Original Correction Method for Indoor Ultra Wide Band Ranging-based Localisation System

{nezo-ibrahim.fofana - adrien.van-den-bossche - rejane.dalce val}@irit.fr Abstract. During this decade, Wireless Sensor Networks (WSNs) brought an increasing interest in the industrial and research world. One of their applications is the indoor localization. The ranging, i.e. the distance evaluation mechanism between nodes, is required to determine the position of the nodes. The research work presented in this article aims to use Ultra Wide Band (UWB) radio links to achieve an efficient ranging, based on Time of Flight (ToF) measurement. A good solution consists in integrating ranging traffic into the usual network mes- sages. However, the ToF ranging process is based on information exchanges which are temporally constrained. Once this information is encapsulated into the usual messages, the temporal constraint cannot be honoured, resulting in important ranging errors due to clock drifts. To mitigate these errors, we have introduced an original dynamic correction technique which enables a precision of twenty centimetres allowing the inclusion of ranging traffic in usual traffic.
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N-TWR: An Accurate Time-of-flight-based N-ary Ranging Protocol for Ultra-Wide Band

N-TWR: An Accurate Time-of-flight-based N-ary Ranging Protocol for Ultra-Wide Band

∗ Corresponding author. E-mail address: vandenbo@univ-tlse2.fr (A. van den Bossche). Such a precision is unacceptable for applications that require a precision in the order of a few tens of centimeters. We will refer to such a localization accuracy as a dozen centimeter-level accu- racy. Ultra-Wide Band (UWB) communication technology combines medium to high data rate communications with positioning capa- bilities offering a ranging precision in the order of few centimeters in a low-power and low-cost context [4–6] . For positioning systems employing UWB radios, time-based schemes provide very good ac- curacy due to the high time resolution of UWB signals. These time- based positioning systems rely on measurements of travel times of signal between nodes. The IEEE 802.15.4a-2007 amendment [7] de- fines a physical layer for low data rate communications combined with positioning capabilities. One of the communication signal for- mat defined by this standard is the Impulse Radio Ultra-Wide Band (IR-UWB). Two different time-based ranging protocols are defined by the standard: Two-Way Ranging (TWR) and Symmetric Dou- ble Sided (SDS)-TWR. Both TWR and SDS-TWR share the objective to estimate the Time of Flight (ToF) between two wireless nodes. The drawback of TWR is that the non time synchronization of the internal clocks of the nodes is not compensated for, leading to inaccurate ToF estimations. SDS-TWR achieves ToF measurements by accounting the clock skews in the ToF calculation, pushing the
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An Original Correction Method for Indoor Ultra Wide Band Ranging-based Localisation System

An Original Correction Method for Indoor Ultra Wide Band Ranging-based Localisation System

Following the results, it appears already some indications that we give to our work. Several ways are being explored. In the near future, a ranging protocol based on the cost-effective use of beacons and data frames will be investigated. As a first step, an improvement of TWR will be proposed to allow a continuous localization, in background, of several neighbors to one hop in a multi-hop topology, in order to achieve the final objective and have a complete localization system included in the protocol stack. Another perspective is to improve the ranging in Non Line-Of-Sight (NLOS) situations: we will have the opportunity to evaluate the performance of the UWB technology which is said to be robust to multipath. Finally, one last perspective concerns the testbed used and its opening to the public we plan to begin by making a set of 10 nodes remotely available to fellow researchers through a web interface. References
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Study of Ultra Wide Band Modulated Backscattering Based RFID Systems

Study of Ultra Wide Band Modulated Backscattering Based RFID Systems

In order to achieve a sub-meter level precision, the majority of current RTLS solutions rely on UWB signals [8, 9]. The adoption of UWB pulses in conjunction with ranging techniques [10, 11], allows sub-nanosecond time resolution, which significantly enhances the localization precision with re- spect to other radio technologies. Recently it has been shown that impulse radio (IR)-UWB is a very promising technique, which could meet the strin- gent requirements of passive tag localization in terms of accuracy [12]. The advantage of such a technology is to provide the typical accuracy of UWB- RTLS by employing a very simple tag, based on a backscattering modulation instead of using a complete UWB active transmitter. However one of the most important issues in these systems is the energy supply as no sufficient energy can be transfered through UWB signals due to severe regulating lim- itations in the emission mask. Combining UWB (semi-)passive RFID with already existing UHF technologies is a possible approach, either through en- ergy harvesting [13] or through the implementation of a wake-up technique in order to increase the battery lifetime. Moreover the UHF module can be employed to ensure compatibility with already existing RFID systems. These technologies are also proposed and studied in the European project SELECT, which is briefly described in Sec. 1.8.
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Doppler effect in the underwater acoustic ultra low frequency band

Doppler effect in the underwater acoustic ultra low frequency band

5 Conclusion We have addressed acoustic communications between AUVs, USs and remote operators. We studied scenarios comprising one transmitter and one or several receivers. Due to the mobility of nodes, the Doppler effect changes the com- munication frequency. We focused on the ULF band, i.e., the frequency range 0.3 to 3 kHz. Numeric simulations confirm the importance of the Doppler shift. We have a maximum Doppler shift of 10 Hz in the scenarios we studied. It is negligible for short and medium ranges. It is, however, significant with respect to the half-power bandwidth for long distance communications (400 km). It corre- sponds to 10% of the half-power bandwidth. Since attenuation also depends on frequency [2–4], a positive Doppler shift increases the frequency and augments the attenuation, and vice-versa. In our simulations, the Doppler effect on the attenuation bandwidth is not significant. The source code of the simulations is available online at http://j.mp/UWtmpgit.
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Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

nanotubes in a single structure, minimizing the possi- bility of such large (>1 μm) aggregations and bundle formation during composite fabrication and thus scat- tering losses while potentially offering high modula- tion depth at a range of wavelengths. Thus, they are potentially an attractive class of carbon nanomaterial for wide-band ultrafast pulse generation. Here, we demonstrate DWNTpolymer composites as wide- band passive mode-lockers for ultrafast pulse genera- tion at 1, 1.5, and 2 μm in Yb-, Er-, and Tm-doped fiber laser cavities, respectively.

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Miniature and Wide-Band ILA Antenna with Non-Foster Matching

Miniature and Wide-Band ILA Antenna with Non-Foster Matching

Keywords—Electrically small antenna, miniaturization, non- Foster I. INTRODUCTION Antenna miniaturization is the key for a compact wireless technology. The main drawbacks of Electrically Small Anten- nas (ESAs) are their low efficiencies and narrow bandwidths even when a passive matching circuit is used. The maximum achievable bandwidth with passive matching is limited by the theoretical limits of Bode-Fano [1] and Chu-Harrington [2], [3]. A possible solution is the use of non-Foster matching that surpass these limits [4] and enhance miniature antenna perfor- mance in reception [5]. A.J. Bahr showed that using an active coupling network with a receiving antenna (a short monopole) can significantly improve its Noise Figure (NF) [6]. Sussman- Fort experimentally showed that using a negative capacitor for matching a 152.4-mm monopole for (20 − 110) MHz frequency band presents a significant improvement in the Signal to Noise Ratio (SNR) compared to the same antenna without matching [7]. Koulouridis and Volakis demonstrated that using a non-Foster circuit to match a 152.4-mm loop can highly increase its bandwidth and decrease its resonance frequency [8]. G. Mishra et al presented a Bowtie antenna covering (0.6 − 1.1) GHz frequency band using a non-Foster circuit [9]. The design of non-Foster circuits becomes more challenging when targeting at higher frequencies (due to the active components non-Linearity) and when targeting high impedance values (due to the parasitic elements).
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Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

Lorentzians. The diameter dependence of G þ and G  peaks can be used to determine the diameter distribu- tion of the nanotubes. 91 This gives an outer tube diameter range of 1.41.8 nm. On the other hand, inner tubes have a diameter distribution in the 0.61.0 nm range. The estimation for the inner tubes agrees well with the results of RBMs and the G region. For the case of the outer tubes, we cannot compare with the RBM data due to the cutoff of the notch/edge filter. However, the data agree with the Raman analysis of the G band and TEM, where a distribution of ∼1.7 nm is estimated for the outer tubes. The 2D bands in Figure 4c, under different excitations, show a spec-
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Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR

Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR

These narrowing profiles at low frequencies might be inter- preted as evidence for fan beam models ( Michel 1987 ). In fan beam models by Dyks et al. ( 2010 ), Dyks & Rudak ( 2012 , 2015 ), for instance, the emission comes from elongated broad-band streams that follow the magnetic field lines. The model, based on the cut angle at which the line of sight crosses the beam, can ex- plain the lack of RFM, for example, if the stream is very narrow (also the case for millisecond pulsars), and it can also explain the “inverse” RFM if there is spectral non-uniformity along the azimuthal direction of the beam through which our line of sight cuts. The fan-beam formulation proposed by Wang et al. ( 2014 ) can even explain “regular” RFM by assuming that a fan beam composed of a (small) number of sub-beams will produce a so- called “limb-darkening pattern” that is caused by the decrease in intensity with beam radius of the emission at higher altitudes because the emission is farther from the magnetic pole. Their model, based on observations and simulations, predicts that the non-circularly bound beam (different in this from the beam pre- dicted by the narrow-band models) can depart from the relation w ∝ P −1/2 (where w is the measured width of the profile, see
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Parallelisation of the Wide-Band Wide-Field Spectral Deconvolution Framework DDFacet on Distributed Memory HPC System

Parallelisation of the Wide-Band Wide-Field Spectral Deconvolution Framework DDFacet on Distributed Memory HPC System

2.2. Multi-Core parallel processing and profiling DDfacet is currently implemented as a functional software based on python and C. A naive description of the imaging framework is described by Fig 1a. In this example, we are working with a set of measured visibility V ν covering the frequency band ν , where ν can be divided into several frequency channels ν i . The imaging framework consists of calculating through an FFT and degridding the predicted visibilities for a specific frequency channel from the sky model b π ν i . Those are then subtracted from

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Ultra-fast relaxation of electrons in wide-gap dielectrics

Ultra-fast relaxation of electrons in wide-gap dielectrics

E ) th 2 , as well as a hard threshold behaviour of the Bethe type: ln(E/E ) th . In Fig. 1, the dielectric loss function Im(-1/ε(ω)) due to excitation of LO phonons and to ionization of valence band electrons (i.i.) are presented in the upper part, further on the respective scattering rates of all mechanisms. Eqs. (1)–(3) are given in the lower part of Fig. 1. The detailed material scattering parameters can be found in Ref. [5].

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Fingerprinting localization based on neural networks and ultra-wideband signals

Fingerprinting localization based on neural networks and ultra-wideband signals

Rennes 35042 France Email : [lei.yu, mohamed.laaraiedh, stephane.avrillon, bernard.uguen]@univ-rennes1.fr Abstract—Fingerprinting techniques have been proved as an effective techniques for determining the position of a mobile user in an indoor environment and in challenging environments such as mines, canyons, and tunnels where common localization techniques based on time of arrival (TOA) or received signal strength (RSS) are subject to big positioning errors. In this paper, a fingerprinting based localization technique using neural networks and ultra-wideband signals (UWB) is presented as an alternative. The fingerprinting database is built with signa- tures extracted from channel impulse responses (CIR) obtained by processing an IR-UWB indoor propagation measurement campaign. The construction of the neural networks and the adopted approach are described. Positioning performances are evaluated with different selected signatures and different sizes of the fingerprinting database.
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AlGaN/GaN High Electron Mobility Transistors with Ultra -Wide Bandgap AlN buffer

AlGaN/GaN High Electron Mobility Transistors with Ultra -Wide Bandgap AlN buffer

AlGaN/GaN High Electron Mobility Transistors with Ultra -Wide Bandgap AlN buffer I. Abid 1* , R. Kabouche 1 , M. Zegaoui 1 , C. Bougerol 2 , R.Comyn 3 , Y. Cordier 3 , F. Medjdoub 1* 1 CNRS-IEMN, UMR8520, Av. Poincaré, 59650 Villeneuve d'Ascq, France 2

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Wigner distribution of amplitude and phase wide-band modulations in induction motor stator current

Wigner distribution of amplitude and phase wide-band modulations in induction motor stator current

However, Concordia Transform requires the previous validation of a particular stator current model in three phase machine in case of mechanical faults. This paper uses the argument of the Fourier Transform for the validation of the model. Using the Hilbert and Concordia transforms of the proposed model, the Wigner-Ville distribution of narrow-band and wide-band frequency modulated signal is expressed. Finally, this paper applies the two transforms on simulated and experimental signals and provides a diagnosis of amplitude or phase modulation in various conditions.
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Resonant Raman scattering in GaAsN: Mixing, localization and band impurity formation of electronic states

Resonant Raman scattering in GaAsN: Mixing, localization and band impurity formation of electronic states

Second, the low frequency scattering is activated be- cause of spatial localization of the resonant electronic states. The localization lenghts ` = 1.25 nm and 1.7 nm were used in the calculations for excitation at 1.91 eV and 1.83 eV, respectively. These values give a good agree- ment between calculated and measured spectral extent and line-shape of the low-frequency scattering (Fig. 2). Different conduction states are probed when changing the excitation energy. Our results indicate that the localiza- tion length increases when electronic states closer to the CBM are selected. This is consistent with the calcula-
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A Complete Si Photonics Platform Embedding Ultra-Low Loss Waveguides for O- and C-Band

A Complete Si Photonics Platform Embedding Ultra-Low Loss Waveguides for O- and C-Band

V. P ASSIVE DEVICE PERFORMANCE As shown in Fig. 1 there is only a minor modification of the waveguide shape with the smoothing annealing. Accordingly, the surface grating fiber coupler performance is not impacted by the annealing step. As shown in Fig. 6, the peak transmission wavelength of annealed grating couplers is unchanged, close to the nominal value of 1310nm (1550nm) in O-band (C-band). Also, the grating fiber coupler insertion loss (~2dB) and bandwidth (~20nm at -1dB) are not impacted by the annealing.

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Linearization of power amplifiers in wide band communication systems by digital baseband  predistortion technique

Linearization of power amplifiers in wide band communication systems by digital baseband predistortion technique

In this dissertation, the techniques of baseband digital predistortion to linearize Power Am- plifiers (PAs) with nonlinear memory effects are we investigated. In chapter 1, the general context and the evolution of wireless communication systems from 1G to 3G and beyond are presented. A brief introduction mainly about transmitters and the design challenges is proposed. The importance to make a good tradeoff between the spectral ef- ficiency and the power efficiency, and the necessity of taking into account the nonlinear memory effect in wide band applications is shown. Some classical distortions due to the nonlinearity of PA (harmonic distortion, intermodulation, spectral regrowth, constellation deformation,...) are described. The important parameters for describing a modulated signal (PAPR, spectral effi- ciency) and that for characterizing the distortions due to the nonlinearity as well as the memory effect of PAs (AM/AM, AM/PM, 1dB compression point, intermodulation, EVM, ACPR, ...) are also introduced.
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Towards a reliability analysis method of wide band gap power electronic components and modules

Towards a reliability analysis method of wide band gap power electronic components and modules

Parent, Guillaume and Massiot, Gregor and Rouet, Vincent and Munier, Catherine and Vidal, Paul-Etienne and Carrillo, Francisco Towards a reliability analysis method of wide band gap power electronic components and modules. (2013) In: European Microelectronics and Packaging Conference , 09 September 2013 - 12 September 2013 (Grenoble, France).

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A very wide band circularly polarized antenna for an amplitude comparison SHF/DF

A very wide band circularly polarized antenna for an amplitude comparison SHF/DF

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB. NRC Publicat[r]

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