Wireless capsule gastrointestinal endoscopy: direction of arrival estimation based localization survey

One of the significant challenges in Capsule Endoscopy (CE) is to precisely determine the pathologies location. The localization process is primarily estimated using the received signal strength from sensors in the capsule system through its movement in the gastrointestinal (GI) tract. Consequently, the wireless capsule endoscope (WCE) system requires improvement to handle the lack of the capsule instantaneous localization information and to solve the relatively low transmission data rate challenges. Furthermore, the association between the capsule’s transmitter position, capsule location, signal reduction and the capsule direction should be assessed. These measurements deliver significant information for the instantaneous capsule localization systems based on TOA (time of arrival) approach, PDOA (phase difference of arrival), RSS (received signal strength), electromagnetic, DOA (direction of arrival) and video tracking approaches are developed to locate the WCE precisely. The current article introduces the acquisition concept of the GI medical images using the endoscopy with a comprehensive description of the endoscopy system components. Capsule localization and tracking are considered to be the most important features of the WCE system, thus the current article emphasizes the most common localization systems generally, highlighting the DOA-based localization systems and discusses the required significant research challenges to be addressed

Kinematic and cyclostationary parameter estimation for co-channel emitter location applications

The problem of locating a signal source, or an emitter, has many civilian and military applications, such as communication regulations enforcement, military reconnaissance, and search-and-rescue operations. Many of the most widely used emitter location methods rely on the accurate and robust estimation of the differential time delay, or time-difference-of-arrival (TDOA), and the differential Doppler shift, or frequency- difference-of-arrival (FDOA), between signal replicas arriving at two spatially separated receivers. There are many conventional methods for estimating TDOA and/or FDOA. However, these methods are unable to produce unbiased TDOA and FDOA estimates when multiple emitters are located spatially close to each other. In many cases, the spatial proximity at which the conventional methods fail is still unacceptably large for precision emitter location applications. This problem is made even more diffcult when separating signals from multiple emitters that share the same regions of the spectrum at the same time. When spatially close emitters overlap spectrally and temporally, robust TDOA and FDOA estimation is diffcult, and accurate emitter location not only requires both estimation of TDOA, or FDOA, or both jointly, but also the estimation of a signal parameter that can be used to separate the signal-of-interest (SOI) from a signal(s)-not-of-interest (SNOI) that are both within the receiver's field of view. The signal separation pa- rameter selected depends on the type of signal modulation. In this thesis, the signals of interest are bauded signals. The separation methodology for such signals is cyclo- stationarity with parameterization by cyclic frequency. Based on this assumption, a new three-dimensional joint estimation method for TDOA, FDOA, and cyclic frequency parameters, called alpha cross ambiguity function (alpha-CAF), has been developed to ex- ploit signal modulations with cyclostationary properties. By exploiting cyclostationarity, alppha-CAF can produce separate unbiased TDOA and FDOA estimates that will in turn yield reliable geolocation estimates for precision emitter location applications even when severe interference causes conventional methods to fail. In this thesis the alpha-CAF param- eter estimation (TDOA, FDOA, Cyclic Frequency) algorithm is introduced along with a complete analysis of its performance compared to conventional estimators. A connection is also made between the alpha-CAF algorithm and the additional steps needed to perform an emitter location technique

Modeling the Behavior of Multipath Components Pertinent to Indoor Geolocation

Recently, a number of empirical models have been introduced in the literature for the behavior of direct path used in the design of algorithms for RF based indoor geolocation. Frequent absence of direct path has been a major burden on the performance of these algorithms directing researchers to discover algorithms using multipath diversity. However, there is no reliable model for the behavior of multipath components pertinent to precise indoor geolocation. In this dissertation, we first examine the absence of direct path by statistical analysis of empirical data. Then we show how the concept of path persistency can be exploited to obtain accurate ranging using multipath diversity. We analyze the effects of building architecture on the multipath structure by demonstrating the effects of wall length and wall density on the path persistency. Finally, we introduce a comprehensive model for the spatial behavior of multipath components. We use statistical analysis of empirical data obtained by a measurement calibrated ray-tracing tool to model the time-of- arrival, angle-of-arrival and path gains. The relationship between the transmitter-receiver separation and the number of paths are also incorporated in our model. In addition, principles of ray optics are applied to explain the spatial evolution of path gains, time-of-arrival and angle-of-arrival of individual multipath components as a mobile terminal moves inside a typical indoor environment. We also use statistical modeling for the persistency and birth/death rate of the paths

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

New Approach of Indoor and Outdoor Localization Systems

Accurate determination of the mobile position constitutes the basis of many new applications. This book provides a detailed account of wireless systems for positioning, signal processing, radio localization techniques (Time Difference Of Arrival), performances evaluation, and localization applications. The first section is dedicated to Satellite systems for positioning like GPS, GNSS. The second section addresses the localization applications using the wireless sensor networks. Some techniques are introduced for localization systems, especially for indoor positioning, such as Ultra Wide Band (UWB), WIFI. The last section is dedicated to Coupled GPS and other sensors. Some results of simulations, implementation and tests are given to help readers grasp the presented techniques. This is an ideal book for students, PhD students, academics and engineers in the field of Communication, localization & Signal Processing, especially in indoor and outdoor localization domains

Sensors and Systems for Indoor Positioning

This reprint is a reprint of the articles that appeared in Sensors' (MDPI) Special Issue on “Sensors and Systems for Indoor Positioning". The published original contributions focused on systems and technologies to enable indoor applications

Analysis of radiofrequency-based methods for position and velocity determination of autonomous robots in lunar surface exploration missions

The use of distributed systems has been disruptive in almost any industrial sector, from manufacturing to processing plants from environmental monitoring to vehicle control, and many more. It is therefore natural to assess the benefits that such an advantageous engineering paradigm could bring to space exploration. In recent years, we have been witness to the emergence of concepts such as fractionated satellite systems, formation flying, megaconstellations, and femtoswarms. Most of these space missions have evolved from the idea of a decentralization of processes that were formerly performed in platforms conceived as monolithic systems. The application of this concept to robotic systems is not new, and a great deal of scientific contributions on multi-robot systems exists, focusing on different aspects such as cooperative robotics, behavioural or reactive control, distributed artificial intelligence, swarm multi-agent systems etc. The intrinsic advantages of distribution (improved reliability and efficiency, higher robustness, etc.) has been boosted by the exponential growing of computational power density and a simultaneous miniaturization of technology, leading to smaller and more powerful robotic platforms, which could make a distributed robotic system, made of small robotic agents, a powerful substitute to classical large robotic platforms. This thesis proposes, in the framework of multi-robot systems, a localization method for robotic agents in planetary surface exploration scenarios based on RF range and Doppler frequency shift analysis. The relevance of spatial localization awareness in agents belonging to a distributed robotic system is defined in the context of the advantages of robotic exploration. Different range determination techniques and, specifically, the advantages of including Doppler Effect in the determination of the relative position within the robotic system deployed are considered and the strengths and weaknesses analysed accordingly. Special attention is devoted to the noise sources present in the lunar environment, related to a practical (i.e. non-ideal) implementation architecture and its influence on the system performance. From this point of view, we develop a theoretical model for localization accuracy estimation, generated from power spectrum characteristics, in accordance with the system architecture proposed, and consolidated with numerical simulations and a parametrical assessment on a set of real references of components playing a key role in the overall performance. The selected system architecture is then implemented in a representative set-up and tested under laboratory conditions. Algorithms used for carrier frequency generation and frequency measurement are developed, applied and tested in the hardware-on-the-loop breadboard. The results show that Doppler frequency component can be measured with the proposed architecture, yielding a high sensitivity in the determination of relative speed even at standard communication frequencies (UHF), and improving significantly at higher bands (S, C, etc.). This enables the possibility of adding relative speed to relative position determination via sensor fusion techniques, improving the response time and accuracy during navigation through the exploration scenario

Wireless indoor localisation within the 5G internet of radio light

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonNumerous applications can be enhanced by accurate and efficient indoor localisation using wireless sensor networks, however trade-offs often exist between these two parameters. In this thesis, realworld and simulation data is used to examine the hybrid millimeter wave and Visible Light Communications (VLC) architecture of the 5G Internet of Radio Light (IoRL) Horizon 2020 project. Consequently, relevant localisation challenges within Visible Light Positioning (VLP) and asynchronous sampling networks are identified, and more accurate and efficient solutions are developed. Currently, VLP relies strongly on the assumed Lambertian properties of light sources. However, in practice, not all lights are Lambertian. To support the widespread deployment of VLC technology in numerous environments, measurements from non-Lambertian sources are analysed to provide new insights into the limitations of existing VLP techniques. Subsequently, a novel VLP calibration technique is proposed, and results indicate a 59% accuracy improvement against existing methods. This solution enables high accuracy centimetre level VLP to be achieved with non- Lambertian sources. Asynchronous sampling of range-based measurements is known to impact localisation performance negatively. Various Asynchronous Sampling Localisation Techniques (ASLT) exist to mitigate these effects. While effective at improving positioning performance, the exact suitability of such solutions is not evident due to their additional processes, subsequent complexity, and increased costs. As such, extensive simulations are conducted to study the effectiveness of ASLT under variable sampling latencies, sensor measurement noise, and target trajectories. Findings highlight the computational demand of existing ASLT and motivate the development of a novel solution. The proposed Kalman Extrapolated Least Squares (KELS) method achieves optimal localisation performance with a significant energy reduction of over 50% when compared to current leading ASLT. The work in this thesis demonstrates both the capability for high performance VLP from non- Lambertian sources as well as the potential for energy efficient localisation for sequentially sampled range measurements.Horizon 202

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance