<p>This thesis considers passive localization and tracking. Here, passive refers to passive observations - the type of observations for which the full position estimate of the target cannot be obtained using a single measurement, like those are from a sonar. Hence, localizing or tracking targets based on these measurements calls for the use of multiple sensors. This poses a different set of challenges to tracking with passive observations as opposed to active observations where full target position is available from a single measurement.</p><p>We identify different issues that are related to passive localization and tracking and propose algorithmic solutions to these problems. We consider the angle of arrival (AOA), which is the passive measurement that is often considered in target tracking and time difference of arrival (TDOA) as representative passive measurements to illustrate our algorithms. Whereas, the AOA measurements from different sensors can be considered independent, TDOA measurements, on the other hand, are not independent. That is, they are correlated. We would, however, like to note that the proposed algorithms can be applied with straightforward, but simple, modifications to other types of passive measurements.</p><p>In particular, this thesis provides solutions to the following problems. First, it provides efficient and improved algorithms to the data association problem when tracking with multiple passive synchronous sensors. These solutions are based on the assignment formulation. Whereas one of the algorithms proposed, the gated assignment algorithm, uses the validation gates to reduce the computational cost, the other is a new extension to the multidimensional assignment algorithm that associates the measurements directly to the tracks. This is called the (S + 1)-D assignment-based data association, where S is the number of synchronous sensors available in the tracking system. An approximation to this new (S + 1)-D algorithm is also presented.</p> <p> In literature one finds algorithms to localize a single target using TDOA measurements. None of these algorithms considered the issues that might arise in tracking the localized targets. This thesis provides a framework to localize and track targets based on TDOA measurements. The localization algorithm uses a formulation based on the sensor-emitter geometry. This formulation is considered as a constrained optimization problem and two relaxation-based algorithms are provided to solve this optimization problem. The assignment-based data association provides an additional challenge because the TDOA measurements are correlated. This problem is identified and a solution is provided by modifying the calculation of the association cost.</p> <p> Finally, this thesis also provides an efficient algorithm to form AOA mono tracks using the fast Fourier transform (FFT) and the assignment algorithm. Formation of the mono tracks is very useful in distributed tracking and is the well-known direction of arrival tracking problem in the signal processing community.</p> / Thesis / Doctor of Philosophy (PhD)

This dissertation was conducted as part of the efforts related to WPI's Precision Personnel Location (PPL) project, the purpose of which is to locate emergency personnel in hazardous indoor environments using radio location techniques. The current PPL system prototype uses a radio transmitter worn by the personnel, indoors, and receivers on reference units, outdoors. This dissertation proposes a new system architecture with bidirectional radio transmissions to replace the current unidirectional system architecture. This allows the development of a synchronization scheme that can extract additional Time of Arrival (TOA) information for estimating the location of personnel. This dissertation also describes an extension of the multi-signal fusion technique previously used that incorporates this TOA information. At the cost of a more complicated mobile unit design, resultant benefits of this approach include rejection of signal reflectors as solutions, improved accuracy with limited reference unit geometries, improved noise rejection and significant computation reduction. In this dissertation the mathematical underpinnings of this approach are presented, a performance analysis is developed and the results are evaluated in the context of experimental data.

Landstinget i Östergötland efterfrågar en högre spårbarhet för läkemedel och övrigt gods. Idag används godsspårningssystemet Arrival, levererat av Pitney Bowes för godsmottagningarna på Universitetssjukhuset i Linköping, Vrinnevisjukhuset i Norrköping samt på Lasarettet i Motala. För att kunna rekommendera vad Landstinget i Östergötland bör tänka på vid upphandling av ett eventuellt nytt godsspårningssystem har deras nuvarande system utvärderats och en omvärldsbevakning av alternativa spårningssystem har genomförts. Studien av Arrival baserades på fältstudier som genomfördes på godsmottagningar på Universitetssjukhuset i Linköping och Lasarettet i Motala samt genom intervjuer med användare och en kunnig brukare av systemet. Denna utvärdering av systemet resulterade i att ett antal förbättringsområden identifierades. I omvärldsbevakningen undersöktes tre alternativa godsspårningssystem från tre olika leverantörer. Ett nyutvecklat godsspårningssystem av ISS, TrueMobile Track and Trace av Optidev samt SendSuite av Pitney Bowes. Resultatet av detta examensarbete är ett antal rekommendationer till Landstinget i Östergötland avseende spårning av gods. Landstinget bör inkludera åsikter från systemanvändare vid upphandling samt erbjuda dem en fullgod utbildning i det initierande stadiet av en eventuell implementering av ett nytt godsspårningssystem. Landstinget bör vidare efterfråga funktioner som avläsningsverktyg som kan synkronisera trådlöst och en funktion för en mer tidseffektiv leverans av flera paket samt se över möjligheterna med RFID.

This study explores the mathematical programming aspects of the air cargo fleet assignment problem for one international air cargo carrier - Korean Air - under given origin-destination (O-D) pairs, departure and arrival times, and frequencies. A pure cargo service is taken as the basis for this study, since such a service is not constrained by passenger route determinants and the schedule of a combination air carrier. The objectives of the study include: to identify the pure air cargo network representation of the combination air carriers; to develop and solve a conventional branch-and-bound mathematical programming model for optimising the assignment of aircraft to flight routes given a set of constraints, including aircraft fleet size, schedule balance, and `required through' constraints; to develop and solve the fleet assignment problem using a novel neural network optimisation modelling approach; to investigate methods of implementing the neural network model, and to analyse the performance of the model when compared with conventional solution methods; and finally to analyse the utility of the neural network model and identify how it may be used in the design and development of air cargo networks for combination air carriers like Korean Air. There are four main parts to the thesis: the first part outlines the schedule design process of an airline and some details of the fleet assignment problem are reviewed. The air cargo flight network is represented and the fleet assignment problem is formulated as a mixed integer programming problem of cost minimisation with various constraints. The complexity of the problem is discussed; the second part outlines the various techniques available to solve optimisation problems and neural network models are presented and discussed as a promising alternative solution method. Neural network applications in the transport field are reviewed and the neural network process for optimisation and for solving the general assignment problem are studied and presented; the third part incorporates the practical application of both the conventional fleet assignment problem solving method and the proposed neural network method to a combination airline's case - Korean Air. The detailed process of constructing a time line network and formulating a mathematical programming model are described and equivalent neural network models are formulated. The results from the two solution approaches are compared and evaluated; and the final part summarises the main findings, presents the significant conclusions, the contribution of the research is discussed and some recommendations for further research are presented. Overall, the conventional branch-and-bound optimisation model yielded plausible results which were demonstrably superior to those produced using the novel neural network optimisation models.

Yes / Underwater communication applications extensively use localization services for object identification. Because of their significant impact on ocean exploration and monitoring, underwater wireless sensor networks (UWSN) are becoming increasingly popular, and acoustic communications have largely overtaken radio frequency (RF) broadcasts as the dominant means of communication. The two localization methods that are most frequently employed are those that estimate the angle of arrival (AOA) and the time difference of arrival (TDoA). The military and civilian sectors rely heavily on UWSN for object identification in the underwater environment. As a result, there is a need in UWSN for an accurate localization technique that accounts for dynamic nature of the underwater environment. Time and position data are the two key parameters to accurately define the position of an object. Moreover, due to climate change there is now a need to constrain energy consumption by UWSN to limit carbon emission to meet net-zero target by 2050. To meet these challenges, we have developed an efficient localization algorithm for determining an object position based on the angle and distance of arrival of beacon signals. We have considered the factors like sensor nodes not being in time sync with each other and the fact that the speed of sound varies in water. Our simulation results show that the proposed approach can achieve great localization accuracy while accounting for temporal synchronization inaccuracies. When compared to existing localization approaches, the mean estimation error (MEE) and energy consumption figures, the proposed approach outperforms them. The MEEs is shown to vary between 84.2154m and 93.8275m for four trials, 61.2256m and 92.7956m for eight trials, and 42.6584m and 119.5228m for twelve trials. Comparatively, the distance-based measurements show higher accuracy than the angle-based measurements.

No description available.

In this thesis, an estimation method adapted from MUSIC algorithm is presented for estimation of signal arrival time for impulse radio UWB systems. An accurate estimate of signal arrival time is considered essential in time-based wireless and indoor location systems. Since most wireless communications systems used for indoor position location may suffer from dense multipath situation, the accuracy of determining signal arrival time become an important issue for the time-based location systems. The fine resolution of UWB signals provides potentially accurate ranging for indoor location applications. However, the ambiguity caused by the unresolved first arrival path may still yield an error in determining the true signal arrival time. The presented method uses improved MUSIC techniques in time domains to estimate the shortest and the real signal arrival time for UWB radio link. For a two-multipath case, analysis and simulation results of multipath resolvability and the variance of estimation errors of signal arrival time are discussed.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / In this paper, we propose a novel technique using a single antenna for direction of arrival (DOA) estimation of broadband microwave signals. We designed and fabricated a microstrip-leaky-wave receiving antenna, which has good matching and reasonable radiation efficiency in the frequency range of interest: 2 - 3.5 GHz. Because the frequency response of the antenna is strongly incident-angle dependent, by using the spectral information at the antenna, we are able to estimate the DOA of a broadband microwave signal with a high degree of accuracy. Simulations and experiments show that the proposed technique enables good DOA estimation performance within a 90˚ range.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Telemetry ground stations spread over geographically diverse areas are well suited for use in passively locating the source of a distant transmitted signal. In a favorable positioning of receive sites, the accuracy of these passive localization techniques can compete with the accuracy of radars. In these cases, use of receive only assets is a less expensive alternative than the use of a radar's scarce resources. Until recently, the major technical challenge to implementation of the passive localization techniques of time-difference of arrival (TDOA) and frequency-difference of arrival (FDOA) has been the frequency and time stability of geographically separated receivers. Advances in GPS based timing and frequency references has made the implementation of TDOA and FDOA feasible. This paper shows how these limitations have been overcome using the current telemetry assets at the Reagan Test Site in Kwajalein Atoll.

This dissertation presents the investigation of antennas with improved performances at microwave frequencies. It covers the following three topics: the study of the metamaterial with near-zero index of refraction and its application in directive antenna design, the design technique of a wideband circularly polarized patch antenna for 60GHz wireless application and the investigation of a novel direction of arrival (DOA) estimation technique inspired by human auditory system. First, the metamaterial composed of two-dimensional (2-D) metallic wire arrays is investigated as an effective medium with an effective index of refraction less than unity (n(eff) < 1). The effective medium parameters (permittivity ε(eff), permeability μ(eff) and n(eff)) of a wire array are extracted from the finite-element simulated scattering parameters and verified through a 2-D electromagnetic band gap (EBG) structure case study. A simple design methodology for directive monopole antennas is introduced by embedding a monopole within a metallic wire array with n(eff) < 1 at the antenna operating frequencies. The narrow beam effect of the monopole antenna is demonstrated in both simulation and experiment at X-band (8 – 12 GHz). The measured antenna properties including return loss and radiation patterns are in good agreement with simulation results. Parametric studies of the antenna system are performed. The physical principles and interpretations of the directive monopole antenna embedded in the wire array medium are also discussed. Second, a fully packaged wideband circularly polarized patch antenna is designed for 60GHz wireless communication. The patch antenna incorporates a diagonal slot at the center and features a superstrate and an air cavity backing to achieve desired performances including wide bandwidth, high efficiency and low axial ratio. The detailed design procedure of the circularly polarized antenna, including the design of the microstrip-fed patch antenna and the comparison of the performances of the antenna with different feeding interfaces, is described. The experimental results of the final packaged antenna agree reasonably with the simulation results. Third, an improved two-antenna direction of arrival (DOA) estimation technique is explored, which is inspired by the human auditory system. The idea of this work is to utilize a lossy scatter, which emulates the low-pass filtering function of the human head at high frequency, to achieve more accurate DOA estimation. A simple 2-monopole example is studied and the multiple signal classification (MUSIC) algorithm is applied to calculate the DOA. The improved estimation accuracy is demonstrated in both simulation and experiment. Furthermore, inspired by the sound localization capability of human using just a single ear, a novel direction of arrival estimation technique using a single UWB antenna is proposed and studied. The DOA estimation accuracies of the single UWB antenna are studied in the x-y, x-z and y-z planes with different Signal to Noise Ratios (SNR). The proposed single antenna DOA technique is demonstrated in both simulation and experiment, although with reduced accuracy comparing with the case of two antennas with a scatter in between. At the end, the conclusions of this dissertation are drawn and possible future works are discussed.