RSSI-Based direction-of-departure estimation in bluetooth low energy using an array of frequency-steered leaky-wave antennas

This paper presents a novel advanced Bluetooth Low Energy (BLE) beacon, which is based on an array of frequency-steered leaky-wave antennas (LWAs), as a transmitter for a Direction-of-Departure (DoD) estimation system. The LWA array is completely passive, fabricated in a low-cost FR4 printed-circuit board and designed to multiplex to different angular directions in space each one of the three associated BLE advertising channels that are used for periodically transmitting the ID of the beacon. This way, the use of more expensive hardware associated to electronic phased-array steering/beam-switching is avoided. Four commercial BLE modules are connected to the four ports of the array, producing an advanced BLE beacon that synthesizes twelve directive beams (one per each port and advertising channel) distributed over a wide Field of View (FoV) of 120 degrees in the azimuthal plane. Then, any BLE enabled IoT device located within this FoV can scan the messages from the beacon and obtain the corresponding Received Signal Strength Indicator (RSSI) of these twelve beams to estimate the relative DoD by using amplitude-monopulse signal processing, thus dispensing from complex In-phase/Quadrature (IQ) data acquisition or high computational load.We propose an angular windowing technique to eliminate angular ambiguities and increase the angular resolution, reporting a root mean squared angular error of 3.7º in a wide FoV of 120º.This work was supported in part by the Spanish National projects TEC2016-75934-C4-4-R and TEC2016-76465-C2-1-R, and in part by the 2018 UPCT Santander Research Grant

Track-Initiated Beam Spoiling for Improved Tracking with Digital Phased-Array Radars

Radar systems have become highly dynamic with the advancements in all-digital radar architectures. All-digital radar architectures introduce the potential for dynamic beamforming. This thesis will detail the fundamentals that are the foundation of radar signal processing (RSP) and modeling a digital phased array radar. This thesis will detail the techniques used for digital beamspoiling. The intentional beamspoiling is intended to improve the trackers’ ability to track a target continuously. When a high-speed target falls out of a beam due to a maneuver, the radar will spoil the transmit beam illuminating a wider scene. The wider illuminated scene allows for a higher likelihood of accurately detecting the target, allowing the tracker to track the target continuously. This thesis will discuss the theory and application of the trackers used in the simulation. With the beamspoiling and trackers, this thesis will analyze the ability of an all-digital phased array to track a target utilizing dynamic beamforming to improve the tracking performance. Finally, it will detail the improvement of the trackers’ ability to track when utilizing beamspoiling for specific situations, allowing the radar to track targets for a more extended time. The results varied based on the amount a transmit beam was spoiled due to the loss in SNR that naturally occurs from the decrease in power density

Monopulse range-doppler FMCW radar signal processing for spatial localization of moving targets

Spatial localization of moving targets using a Monopulse/FMCW Radar system signal processing scheme is presented in this work. During many years radar sensor application has been used to measure different target parameters and consecutively leading to spatial localization systems, so that has been an active research area in many important fields, from military to civilian applications. Spatial localization of moving targets consists of sensing and estimating the coordinates where the target is located and its speed and direction. The immediate goal of this work is to measure the distance, velocity and angle parameters of each target detected basing on a set of FMCW-Radar measurements and a monopulse phase comparison method, therefore obtaining spatial localization of moving targets scheme, taking into account that the localization area should be limited depending on the radar sensor used and its features. Like this, there is a need to achieve the localization with the best possible measurement accuracy and in any situation, and this can be solved with a simple and cheap technology as mm-wave FMCW radars, that are remarkable because work-well in harsh environments and have a very high resolution for ranging, velocity and imaging method, a distance measurement resolution of 2 cm can be easily achieved over 30-40 meters working at 24GHz. Moreover the method presented is especially suited to detect very weak moving targets. Many applications where FMCW radar and Monopulse radar are playing an important role are: disaster situations of buried alive people, level-measuring systems, dimension verification systems, wall penetrating applications, air traffic control, terrain avoidance systems, etc [1]. It is clear that all cited applications could become more attractive and useful by using a suitable localization method as presented in this work. Besides the theoretical development and explanation of the proposed method, exemplary situations and measurements results will be presented to illustrate the capability of the algorithm. Real measurements will be made using a Monopulse/FSK/FMCW Radar with one transmitter / two receiver antennas at K-band. The signal evaluation was applied on a field programmable gate array (FPGA) to facilitate real time processing.Escuela Técnica Superior de Ingeniería de TelecomunicaciónUniversidad Politécnica de Cartagen

Nuevos sistemas de Localización INDoor de dispositivos IoT (LINDIOT)

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Los sistemas de localización de los dispositivos que forman el Internet de las Cosas (loT) se basan, habitualmente, en sistemas satelitales (GNSS). Sin embargo, debido a la dificultad que tienen las ondas electromagnéticas de atravesar las paredes y techos de los edificios, los sistemas satelitales no ofrecen una precisión adecuada en interiores de edificios. Por lo tanto, no pueden ser empleados en aplicaciones como localización, navegación o guiado de personas en estos entornos. Al no poder emplearse los sistemas de localización satelitales, se han desarrollado diversas propuestas, algunas propietarias y otras de ámbito científico, que permiten la localización de dispositivos loT en entornos indoor. Estas propuestas emplean tecnologías tan diversas como imagen, radiofrecuencia, sensores inerciales, sensores de campo magnético, e incluso señales acústicas. En esta tesis nos centraremos en los sistemas basados en radiofrecuencia, dado que se trata de los más ampliamente utilizados. Dentro de los sistemas basados en radiofrecuencia, dependiendo de la infraestructura empleada y del propósito del mismo, se pueden emplear diferentes tecnologías para su funcionamiento, entre ellas destacan: WiFi, Zigbee, UWB o Blueetooth Low Energy. La tecnología WiFi ha sido una de las predominantes a la hora de implementar los sistemas de localización en interiores, sobre todo en grandes edificios con gran número de visitantes como son aeropuertos, centros comerciales, museos, etc. Esto se debe a que en este tipo de instalaciones suele existir una amplia red WiFi desplegada para dotar de conectividad a los visitantes. Esta red puede ser empleada a su vez para la generación de sistemas de localización, ahorrando así el despliegue de nueva infraestructura. Se ha de tener cuenta que el coste del despliegue de infraestructura, incluyendo equipos, cableado, ingeniería, etc., suele ser una de las tareas más costosas dentro de cualquier proyecto de ingeniería. Es por ello que se tiende a reutilizar las redes WiFi-existentes dotándolas de otras funcionalidades, además de la propia de conectividad. Una de las principales clasificaciones de los sistemas de localización suele dividir a los mismos entre sistemas activos y pasivos. Los sistemas activos requieren la intervención del dispositivo a localizar mediante una aplicación y/o proceso que recoge información del espectro RF a su alcance, mientras que los sistemas pasivos recogen la señal RF de los dispositivos loT que detectan, pero no requieren de su participación. Durante el desarrollo de esta tesis se ha trabajado en los dos tipos de sistemas, estando dividida la investigación en dos partes claramente diferenciadas. En la primera parte de la tesis se ha trabajado en los sistemas de localización pasivos, concretamente en sistemas de localización mediante la técnica conocida como radar monopulso empleando el estándar WiFi 802.11. Posteriormente se trabajó en la técnica radar monopulso en campo cercano y, a continuación, se combinó con sistemas de ranging basados en el estándar 802.llmc. Mediante la combinación de ambas tecnologías se generó un sistema de localización empleando un único punto de acceso (AP). Por último, el trabajo final de este bloque empleó antenas de haz con escaneo en frecuencia, técnicas de channel-hopping y el algoritmo MUSIC para ampliar el FoV de los dispositivos pasivos implementados en el trabajo anteriore. En la segunda parte de la tesis se ha trabajado en la implementación de un IPS (lndoor Positioning System) de smartphones para grandes superficies, empleando únicamente los APs que ya se encuentran instalados y con una precisión zonal a nivel tienda/pasillo. El IPS es una de las piezas fundamentales de un mecanismo mayor conocido como Sistema de Marketing Contextual. Junto con la descripción detallada del IPS, se explican todos los componentes e intercambios de información entre los diferentes bloques que forman el Sistema de Marketing Contextual. [ENG] This doctoral dissertation has been presented in the form of thesis by publication. the location and positioning systems involved in the Internet of the Things (IoT) paradigm are generally based on satellite systems (GNSS). However, because the electromagnetic waves have difficulties getting through the walls and roof of the buildings, the satellite systems do not have enough accuracy indoors. Therefore, this kind of system cannot be employed in the location and navigation of IoT devices or people indoor. Because satellite tracking systems cannot be employed, several proposals are focused on overcoming the indoor location of IoT devices. Some proposals are from the scientific area, and some other proposals are proprietary. These proposals employ different technologies like image-based, radiofrequency, inertial sensors, magnetic field sensors, and acoustic signals. This Ph.D. thesis will focus on radio frequency-based systems because they are the most frequently used. Among the radio frequency-based systems, several technologies can be employed according to the infrastructure employed and the purpose of the project. These technologies are WiFi, Zigbee, UWB, or Bluetooth Low Energy. WiFi technology has been one of the most employed in indoor location systems, particularly in large infrastructures with a high number of visitors such as airports, malls, museums, etc. This is mainly because there is often a wide WiFi network already deployed to provide connectivity to visitors in this kind of infrastructure. This network could also be employed to implement the location system, saving savings in deploying the system. It should be taken into consideration that the main cost of any project is the infrastructure deployment phase, where the wiring and the new equipment acquisition are carried out. Because of the aforementioned cots, the WiFi networks are often reused with other applications than the data connectivity. One of the main classifications of the indoor location system usually divides them into active and passive. The active systems require the participation of the device to be located by using an app that collects the data from the RF within the range. However, the passive systems collect the RF signal of the IoT devices within the range but do not require their involvement. In this thesis, we have worked on the two kinds of systems. In the first chapters, we have worked in the passive location systems, mainly in the WiFi RADAR monopulse function-based systems based on the 802.11 standard. Next, we focused on the near-field monopulse technique, and later we merged this technique with a ranging system based on the 802.11mc standard. The last work of this section employed a frequency beam antenna with channelhopping techniques and the MUSIC algorithm to increase the FoV of the previously implemented devices. In the following chapters, we work on implementing a smartphone Indoor Positioning System (IPS) for large infrastructures. One of the main premises of our IPS is the use of the already deployed APs with zonal accuracy. The IPS is one of the key enabling technologies of a Marketing Contextual System. Moreover, the component and information flows between the different blocks that make up the Contextual Marketing System are explained.[ENG] This doctoral dissertation has been presented in the form of thesis by publication. The location and positioning systems involved in the Internet of the Things (IoT) paradigm are generally based on satellite systems (GNSS). However, because the electromagnetic waves have difficulties getting through the walls and roof of the buildings, the satellite systems do not have enough accuracy indoors. Therefore, this kind of system cannot be employed in the location and navigation of IoT devices or people indoor. Because satellite tracking systems cannot be employed, several proposals are focused on overcoming the indoor location of IoT devices. Some proposals are from the scientific area, and some other proposals are proprietary. These proposals employ different technologies like image-based, radiofrequency, inertial sensors, magnetic field sensors, and acoustic signals. This Ph.D. thesis will focus on radio frequency-based systems because they are the most frequently used. Among the radio frequency-based systems, several technologies can be employed according to the infrastructure employed and the purpose of the project. These technologies are WiFi, Zigbee, UWB, or Bluetooth Low Energy. WiFi technology has been one of the most employed in indoor location systems, particularly in large infrastructures with a high number of visitors such as airports, malls, museums, etc. This is mainly because there is often a wide WiFi network already deployed to provide connectivity to visitors in this kind of infrastructure. This network could also be employed to implement the location system, saving savings in deploying the system. It should be taken into consideration that the main cost of any project is the infrastructure deployment phase, where the wiring and the new equipment acquisition are carried out. Because of the aforementioned cots, the WiFi networks are often reused with other applications than the data connectivity. One of the main classifications of the indoor location system usually divides them into active and passive. The active systems require the participation of the device to be located by using an app that collects the data from the RF within the range. However, the passive systems collect the RF signal of the IoT devices within the range but do not require their involvement. In this thesis, we have worked on the two kinds of systems. In the first chapters, we have worked in the passive location systems, mainly in the WiFi RADAR monopulse function-based systems based on the 802.11 standard. Next, we focused on the near-field monopulse technique, and later we merged this technique with a ranging system based on the 802.11mc standard. The last work of this section employed a frequency beam antenna with channelhopping techniques and the MUSIC algorithm to increase the FoV of the previously implemented devices. In the following chapters, we work on implementing a smartphone Indoor Positioning System (IPS) for large infrastructures. One of the main premises of our IPS is the use of the already deployed APs with zonal accuracy. The IPS is one of the key enabling technologies of a Marketing Contextual System. Moreover, the component and information flows between the different blocks that make up the Contextual Marketing System are explained.Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Está formada por estos seis artículos: 1. J. L. Gómez-Tornero, D. Cañete-Rebenaque, J. A. López-Pastor and A. S. Martínez-Sala, "Hybrid Analog-Digital Processing System for Amplitude-Monopulse RSSI-Based MiMo WiFi Direction-of-Arrival Estimation," in IEEE Journal of Selected Topics in Signal Processing, vol. 12, no. 3, pp. 529-540, June 2018, doi: 10.1109/JSTSP.2018.2827701. 2. J. A. López-Pastor, A. Gómez-Alcaraz, D. Cañete-Rebenaque, A. S. Martinez-Sala and J. L. Gómez-Tornero, "Near-Field Monopulse DoA Estimation for Angle-Sensitive Proximity WiFi Readers," in IEEE Access, vol. 7, pp. 88450-88460, 2019, doi: 10.1109/ACCESS.2019.2925739. 3. J. A. López-Pastor, P. Arques-Lara, J. J. Franco-Peñaranda, A. J. García-Sánchez and J. L. Gómez-Tornero, "Wi-Fi RTT-Based Active Monopulse RADAR for Single Access Point Localization," in IEEE Access, vol. 9, pp. 34755-34766, 2021, doi: 10.1109/ACCESS.2021.3062085. 4. J. A. López-Pastor, A. J. Ruiz-Ruiz, A. J. García-Sánchez, and J. L. Gómez-Tornero, “An automatized contextual marketing system based on a wi-fi indoor positioning system,” Sensors, vol. 21, no. 10, pp. 1–26, 2021 5. J. A. Lopez-Pastor, A. J. Ruiz-Ruiz, A. S. Martinez-Sala, and J. Luis Gomez-Tornero, “Evaluation of an indoor positioning system for added-value services in a mall,” in 2019 International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2019, pp. 1–8 6. A. Gil-martínez, M. Poveda-garcía, J. A. López-pastor, J. C. Sánchez-aarnoutse, and J. L. Gómez-tornero, “Wi-Fi Direction Finding with Frequency-Scanned Antenna and Channel-Hopping Scheme,” IEEE Sens. J., vol. XX, no. Xx, pp. 1–9, 2021.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Tecnologías de la Información y las Comunicacione

Performance Analysis of Angle of Arrival Algorithms Applied to Radiofrequency Interference Direction Finding

Radiofrequency (RF) interference threatens the functionality of systems that increasingly underpin the daily function of modern society. In recent years there have been multiple incidents of intentional RF spectrum denial using terrestrial interference sources. Because RF based systems are used in safety-of-life applications in both military and civilian contexts, there is need for systems that can quickly locate these interference sources. In order to meet this need, the Air Force Research Laboratory Weapons Directorate is sponsoring the following research to support systems that will be able to quickly geolocate RF interferers using passive angle-of-arrival estimation to triangulate interference sources. This research studies the performance of angle-of arrival (AoA) estimation algorithms for an existing uniform linear antenna array. Four algorithms are presented, they are phase-shift beamforming, Capon or Minimum Variance Distortionless Response (MVDR) beamforming, the Multiple Signal Identification and Classification (MUSIC) algorithm, and one instantiation of a Maximum Likelihood Estimation (MLE) algorithm. A modeling and simulation environment using MATLAB™ is developed and the performance of each algorithm is simulated as implemented on a uniform linear array. Performance is characterized under various non-ideal conditions

Analysis and Design of Ultra-Wideband Transceiver and Array

Ph.DDOCTOR OF PHILOSOPH

Study to investigate and evaluate means of optimizing the radar function

The investigations for a rendezvous radar system design and an integrated radar/communication system design are presented. Based on these investigations, system block diagrams are given and system parameters are optimized for the noncoherent pulse and coherent pulse Doppler radar modulation types. Both cooperative (transponder) and passive radar operation are examined including the optimization of the corresponding transponder design for the cooperative mode of operation

Information Theoretic Limits on Non-cooperative Airborne Target Recognition by Means of Radar Sensors

The main objective of this research is to demonstrate that information theory, and specifically the concept of mutual information (MI) can be used to predict the maximum target recognition performance for a given radar concept in combination with a given set of targets of interest. This approach also allows for the direct comparison of disparate approaches to designing a radar concept which is capable of target recognition without resorting to choosing specific feature extraction and classification algorithms. The main application area of the study is the recognition of fighter type aircraft using surface based radar systems, although the results are also applicable to airborne radars. Information theoretic concepts are developed mathematically for the analysis of the radar target recognition problem. The various forms of MI required for this application are derived in detail and are tested rigorously against results from digital communication theory. The results are also compared to Shannon’s channel capacity bound, which is the fundamental limit on the amount of information which can be transmitted over a channel. Several sets of simulation based experiments were conducted to demonstrate the insights achievable by applying MI concepts to quantitatively predict the maximum achievable performance of disparate approaches to the radar target recognition problem. Asymptotic computational electromagnetic code was applied to calculate the target’s response to the radar signal for freely available geometrical models of fighter aircraft. The calculated target responses were then used to quantify the amount of information which is transmitted back to the radar about the target as a function of signal to noise ratio (SNR). The information content of the F-14, F-15 and F-16 were evaluated for a 480 MHz bandwidth waveform at 10 GHz as a baseline. Several ultra-wideband (UWB) waveforms, spanning 2-10 GHz, 10- 18 GHz and 2-18 GHz, but which were highly range ambiguous, were evaluated and showed SNR gains of 0.5-2 dB relative to the baseline. The effect of sensing the full polarimetric response of an F-18 and F-35 was evaluated and SNR gains of 5-7 dB over a single linear polarisation were measured. A Boeing 707 scale model (1:25) was measured in the University of Pretoria’s compact range spanning 2-18 GHz and gains of 2 dB were observed between single and dual linear polarisations. This required numerical integration in 8004 dimensions, demonstrating the stability of the MI estimation algorithm in high dimensional signal spaces. The information gained by including the difference channel signal of an X-band monopulse radar for the F-14 data set was approximately 3 dB at 50 km and increased to 4.5 dB at 2 km due to the increased target extent relative to the antenna pattern. This experiment necessitated the use of target profiles which were matched to the range of the target to achieve maximum information transfer. Experiments were conducted to evaluate the loss in information due to envelope processing. For the baseline data set, SNR losses in the region of 7 dB were measured. Linear pre-processing using the fast Fourier transform (FFT) and principal component analysis (PCA), before envelope processing, were compared and the PCA algorithm outperformed the FFT by approximately 1 dB at high MI values. Finally, the expression for multi-target MI was applied in conjunction with Fano’s inequality to predict the probability of incorrectly classifying a target. Probability of error is a critical parameter for a radar user. For the baseline data set, at P(error) = 0.001, maximum losses in the region of 0.6 to 0.9 dB were measured. This result shows that these targets are easily separable in the signal space. This study was only the proverbial “tip of the iceberg” and future research could extend the results and applications of the techniques developed. The types of targets and configurations of the individual targets could be increased and analysed. The analysis should also be extended to describe effects internal to the radar such as phase noise, spurious signals and analogue to digital converters and external effects such as clutter and multipath. The techniques could also be applied to quantify the gains in target recognition performance achievable for multistatic radar, multiple input multiple output (MIMO) radar and more exotic concepts, such as the fusion of data from multiple monostatic microwave radars with multi-receiver multi-band passive bistatic radar (PBR) data