Dissertations / Theses on the topic 'PATH-LOSS MODEL'

This thesis presents a grid-based indoor radiolocation technique based on a Spatially Coherent Path Loss Model (SCPL). SCPL is a path loss model which characterizes the radio wave propagation in an environment by solely using Received Signal Strength (RSS) fingerprints. The propagation of the radio waves is characterized by uniformly dividing the environment into grid cells, followed by the estimation of the propagation parameters for each grid cell individually. By using SCPL and RSS fingerprints acquired at an unknown location, the distance between an agent and all the access point in an indoor environment can be determined. A least-squares based trilateration is then used as the global fix of location the agent in the environment. The result of the trilateration is then represented in a probability distribution function over the grid cells induced by SCPL. Since the proposed technique is able to locally model the propagation accounting for attenuation of non-uniform environmental irregularities, the characterization of the path loss in the indoor environment and radiolocation technique might yield improved results. The efficacy of the proposed technique was investigated with an experiment comparing SCPL and an indoor radiolocation technique based on a conventional path loss model.
Master of Science
This thesis presents a technique uses radio waves to localize an agent in an indoor environment. By characterizing the difference between transmitted and received power of the radio waves, the agent can determine how far it is away from the transmitting antennas, i.e. access points, placed in the environment. Since the power difference mainly results from obstructions in the environment, the attenuation profile of the environment carries a significant importance in radiolocation techniques. The proposed technique, called Spatially Coherent Path Loss Model (SCPL), characterizes the radio wave propagation, i.e. the attenuation, separately for different regions of the environment, unlike the conventional techniques employing global attenuation profiles. The localization environment is represented with grid-cell structure and the parameters of SCPL model describing the extent of the attenuation of the environment are estimated individually. After creating an attenuation profile of the environment, the agent localizes itself in the localization environment by using SCPL with signal powers received from the access points. This scheme of attenuation profiling constitutes the main contribution of the proposed technique. The efficacy and validity of the proposed technique was investigated with an experiment comparing SCPL and an indoor radiolocation technique based on a conventional path loss model.

The most common railroad accidents today involve collisions between trains and passenger vehicles at railroad grade crossings [1][2]. Due to the size and speed of a train, these collisions generally result in significant damage and serious injury. Despite recent efforts by projects such as Operation Lifesaver to install safety features at grade crossings, up to 80% of the United States railroad grade crossings are classified as 'unprotected' with no lights, warnings, or crossing gates [2]. Further, from January to September 2012, nearly 10% of all reported vehicle accidents were a result of train-to-vehicle collisions. These collisions also accounted for nearly 95% of all reported fatalities from vehicular accidents [2]. To help provide a more rapidly deployable safety system, advanced dedicated short range communication (DSRC) systems are being developed. DSRC is an emerging technology that is currently being explored by the automotive safety industry for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide intelligent transportation services (ITS). DSRC uses WAVE protocols and the IEEE 1609 standards. Among the many features of DSRC systems is the ability to sense and then provide an early warning of a potential collision [6]. One potential adaption for this technology is for use as a train-to-vehicle collision warning system for unprotected grade crossings. These new protocols pose an interesting opportunity for enhancing cybersecurity since terrorists will undoubtedly eventually identify these types of mass disasters as targets of opportunity. To provide a thorough channel model of the train to vehicle communication environment that is proposed above, large-scale path loss and small scale fading will both be analyzed to characterize the propagation environment. Measurements were collected at TTCI in Pueblo Colorado to measure the received signal strength in a train to vehicle communication environment. From the received signal strength, different channel models can be developed to characterize the communication environment. Documented metrics include large scale path loss, Rician small scale fading, Delay spread, and Doppler spread. An analysis of the DSRC performance based on Packet Error Rate is also included.
Master of Science

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV
Tracking small marmosets over a large area represents a significant challenge for researchers. The native habitat for such animals are generally unsuitable for GPS based location systems, and the size of the animals prevents large, feature-rich collars from being utilized. Additionally, costs and feasibility prevent researchers from continuously monitoring these animals on the ground. This paper proposes a new system of tracking that offsets complexity from the collar onto fixed Base Stations (BS). The simplified collars emit a ping that multiple BSs then log along with the power of the signal. Combining the data from different BSs allows for the determination of the Signal of Interest (SOI). It was found that using three BSs provided enough accuracy to determine the location of an SOI within an accuracy of 2 m² over a roughly 450 m² area.

Careful network planning has become increasingly critical with the rising deployment, coverage, and congestion of wireless local area networks (WLANs). This thesis outlines the achieved prediction accuracy of a direct-ray, single path loss exponent, adapted Seidel-Rappaport propagation model as determined through measurements and analysis of the established 2.4 GHz, 802.11g outdoor WiFi network deployed on the campus of the Georgia Institute of Technology. Additionally, the viability of using the obtained model parameters as a means for planning future network deployment is discussed. Analysis of measured data shows that accurate predictive planning for network coverage is possible without the need for overly complicated modeling techniques such as ray tracing. The proposed model performs with accuracy comparable to other commonly accepted, more complicated models and is offered as a simple, yet strong predictive model for network planning having both speed and accuracy. Results show, that for the area under study, the standard deviation of the prediction error for the proposed model is below 6.8dB in all analyzed environments, and is approximately 5.5dB on average. Further, the accuracy of model predictions in new environments is shown to be satisfactory for network planning.

Our related research review on propagation models reveals six factors that are significant in last mile connectivity via LAP: path loss, elevation angle, LAP altitude, coverage area, power consumption, operation frequency, interference, and antenna type. These factors can help with monitoring system performance, network planning, coverage footprint, receivers' line-of-sight, quality of service requirements, and data rates which may all vary in response to geomorphology characteristics. Several competing propagation models have been proposed over the years but whilst they collectively raise many shortcomings such as limited altitude up to few tens of meters, lack of cover across different environments, low perdition accuracy they also exhibit several advantages. Four propagation models, which are representatives of their types, have been selected since they exhibit advantages in relation to high altitude, wide coverage range, adaption across different terrains. In addition, all four have been extensively deployed in the past and as a result their correction factors have evolved over the years to yield extremely accurate results which makes the development and evaluation aspects of this research very precise. The four models are: ITU-R P.529-3, Okumura, Hata-Davidson, and ATG. The aim of this doctoral research is to design a new propagation model for last-mile connectivity using LAPs technology as an alternative to aerial base station that includes all six factors but does not exhibit any of the shortcomings of existing models. The new propagation model evolves from existing models using machine learning. The four models are first adapted to include the elevation angle alongside the multiple-input multiple-output diversity gain, our first novelty in propagation modelling. The four adapted models are then used as input in a Neural Network framework and their parameters are clustered in a Self-Organizing-Map using a minimax technique. The framework evolves an optimal propagation model that represents the main research contribution of this research. The optimal propagation model is deployed in two proof-of-concept applications, a wireless sensor network, and a cellular structure. The performance of the optimal model is evaluated and then validated against that of the four adapted models first in relation to predictions reported in the literature and then in the context of the two proof-of-concept applications. The predictions of the optimised model are significantly improved in comparison to those of the four adapted propagation models. Each of the two proof-of-concept applications also represent a research novelty.

VHF står för "Very High Frequency" och är ett frekvensband som ligger i området 30 - 300 MHz. Maritim VHF är standard för Sjöfartsverket och fungerar över hela världen. Det är ett kommunikationssystem som bidrar till ökad säkerhet och kan rädda liv på sjön. Andra vanliga kommunikationssystem som mobiltelefoni fungerar inte tillförlitligt. Idag fungerar mobiltelefoni i stora delar av skärgården och längs kusterna men när det gäller kommunikation mellan fartyg längre ut till havs är den maritima VHF-kommunikationen överlägsen. Sjöfartsverket driver för sitt eget och kunders behov ett mobilradionätverk kallat kustradionätverket. Radiotrafiken i nätet sker både på Very High Frequency (VHF) och Medium frequency (MF). VHF-systemet är ett internationellt system som bland annat används till att kommunicera till sjöss och den trafiken befinner sig i frekvensbandet 155.5 - 162.025 MHz. Inom VHF-bandet finns det 55 kanaler. Kanalerna vid kustradiostationen kallas för duplexkanaler och innebär att kustradiostationerna sänder och tar emot signaler på två olika frekvenser. Radioutbredningen hos antennen som är installerad på basstationen har riktverkan i vissa riktningar och dämpningar i andra. Detta kan ses i strålningsdiagrammet under kapitlet "Täckningsmodell" och avsnittet antennen. Andra faktorer som kan påverka radioutbredningen är förluster i basstationenssystemet, topologin hos området mellan sändare och mottagare samt väderberoende utbredningsegenskaper. Genom att hitta de tänkbara faktorer som påverkar signalutbredningen kan en täckningsmodell förutses. Det är förluster som finns i basstationen, radiolänken samt förluster vid mottagarantennen.

The subject of this thesis is the development of localization algorithms for target localization in wireless sensor networks using received signal strength (RSS) measurements or Quantized RSS (QRSS) measurements. In chapter 3 of the thesis, target localization using RSS measurements is investigated. Many existing works on RSS localization assumes that the shadowing components are uncorrelated. However, here, shadowing is assumed to be spatially correlated. It can be shown that localization accuracy can be improved with the consideration of correlation between pairs of RSS measurements. By linearizing the corresponding Maximum Likelihood (ML) objective function, a weighted least squares (WLS) algorithm is formulated to obtain the target location. An iterative technique based on Newtons method is utilized to give a solution. Numerical simulations show that the proposed algorithms achieves better performance than existing algorithms with reasonable complexity. In chapter 4, target localization with an unknown path loss model parameter is investigated. Most published work estimates location and these parameters jointly using iterative methods with a good initialization of path loss exponent (PLE). To avoid finding an initialization, a global optimization algorithm, particle swarm optimization (PSO) is employed to optimize the ML objective function. By combining PSO with a consensus algorithm, the centralized estimation problem is extended to a distributed version so that can be implemented in distributed WSN. Although suboptimal, the distributed approach is very suitable for implementation in real sensor networks, as it is scalable, robust against changing of network topology and requires only local communication. Numerical simulations show that the accuracy of centralized PSO can attain the Cramer Rao Lower Bound (CRLB). Also, as expected, there is some degradation in performance of the distributed PSO with respect to the centralized PSO. In chapter 5, a distributed gradient algorithm for RSS based target localization using only quantized data is proposed. The ML of the Quantized RSS is derived and PSO is used to provide an initial estimate for the gradient algorithm. A practical quantization threshold designer is presented for RSS data. To derive a distributed algorithm using only the quantized signal, the local estimate at each node is also quantized. The RSS measurements and the local estimate at each sensor node are quantized in different ways. By using a quantization elimination scheme, a quantized distributed gradient method is proposed. In the distributed algorithm, the quantization noise in the local estimate is gradually eliminated with each iteration. Simulations show that the performance of the centralized algorithm can reach the CRLB. The proposed distributed algorithm using a small number of bits can achieve the performance of the distributed gradient algorithm using unquantized data.

This Master thesis deals with wave propagation and starts with wave propagation basics. It briefly presents the theory for the diffraction over terrain obstacles and describes two different path loss models, the Hata model and a FFT-based model. The significance of this paper is that it gives the simulation results for the models mentioned above and presents a comparison between the results obtained from an empirical formula and the FFT-model. The comparison shows that the approach based on Fast Fourier Transform is good enough for prediction of the path loss and that it is a time efficient method.

In the push for spectrum sharing and open spectrum access, the 3.5 GHz frequency band is under consideration for small cells and general Wireless Local Area Networks (WLAN) in the United States. The same band is beginning to see deployment in China, Japan, and South Korea, for the 4G Long Term Evolution (LTE) cellular standard to increase coverage and capacity in urban areas through small cell deployment. However, since the adoption of this band is new, there is a distinct shortage of propagation data and accurate channel modeling at 3.5 GHz in indoor environments. These models are necessary for cellular coverage planning and evaluating the performance and feasibility of wireless systems. This report presents the results of a fixed wireless channel measurement campaign at 3.5 GHz. Measurements were taken in environments typical of indoor wireless deployment: traditional urban indoor office, hallway, classroom, computer laboratory, and atrium areas, as well as within a hospital. Primarily Non Line of Sight (NLOS) experiments were carried out in areas with a controllable amount of partitions separating the transmitter and receiver in order to document material-based attenuation values. Indoor-to-outdoor measurements were carried out, focusing on attenuation due to common exterior building materials such as concrete, brick, wood, and reinforced glass. Documented metrics include large scale path loss, log-normal shadowing, and channel power delay profiles combined with delay spread characteristics for multipath analysis. The statistical multi-antenna diversity gain was evaluated to gauge the benefit of using multi-antenna systems in an indoor environment, which has much greater spatial diversity than an outdoor environment. Measurements were compared to indoor path loss models used for WLAN planning in the low GHz range to investigate the applicability of extending these models to 3.5 GHz.
Master of Science

The radio wave propagation prediction is one of the key elements for designing an efficient radio network system. WRAP International has developed a software for spectrum management and radio network planning.This software includes some wave propagation models which are used to predict path loss. Current propagation models in WRAP perform the calculation in a vertical 2D plane, the plane between the transmitter and the receiver. The goal of this thesis is to investigate and implement a 3D wave propagation model, in a way that reflections and diffractions from the sides are taken into account.The implemented 3D wave propagation model should be both fast and accurate. A full 3D model which uses high resolution geographical data may be accurate, but it is inefficient in terms of memory usage and computational time. Based on the fact that in urban areas the strongest path between the receiver and the transmitter exists with no joint between vertical and horizontal diffractions [10], the radio wave propagation can be divided into two parts, the vertical and horizontal part. Calculations along the horizontal and vertical parts are performed independently, and after that, the results are combined. This approach leads to less computational complexity, faster calculation time, less memory usage, and still maintaining a good accuracy.The proposed model is implemented in C++ and speeded up using parallel programming techniques. Using the provided Stockholm high resolution geographical data, simulations are performed and results are compared with real measurements and other wave propagation models. In addition to the path loss calculation, the proposed model can also be used to estimate the channel power delay profile and the delay spread.

The dissertation concerns about the path loss calculation of Radio Frequency (RF) propagation models for 4G Long Term Evolution (LTE) Network to prefer the best Radio Frequency propagation model. The radio propagation models are very significant while planning of any wireless communication system. A comparative analysis between radio propagation models e.g. SUI model, Okumura model, Cost 231 Hata Model, Cost 231-Walfisch Ikegami and Ericsson 9999 model that would be used for outdoor propagation in LTE. The comparison and performance analysis has been made by using different geological environments e.g. urban, sub-urban and rural areas. The simulation scenario is made to calculate the lowest path loss in above defined environments by using selected frequency and height of base station antennas while keeping a constant distance between the transmitter and receiver antennas.
Asad Saeed C/O Muhammad Awais Hovslagargatan 47 LGH 1004 19431 Stockholm Sweden Mob: 0046723333734

In this thesis electromagnetic wave propagation is investigated in an indoor environment. The indoor environment is a furnished office building with corridors, corners and rooms. Particularly, there is an atrium through the building in the center. For the study there were measurements available from real building in the 2.1 GHz frequency band. One objective is to design a propagation model that should be simple but reflect the trend of the propagation measurements. Furthermore, a system performance evaluation is carried out based on the implemented model. The proposed 3D model is a combination of the Free Space Path Loss model, the Keenan-Motley model and the recursive diffraction model. The channel predictions from the 2D Keenan-Motley algorithm are quite different from the measurements. Therefore, the 3D Keenan-Motley algorithm is designed to depict the atrium effect and speed up the simulation at the same time. Besides a buttery radiation diagram is created to mimic Kathrein 80010709 antenna installed in the building. Finally, a diffracted path is added to improve the received signal strength for the users around the atrium areas. With all the above procedures, the final results from the model are in good quantitative agreement with the measurement data. With the implemented propagation model, a further analysis of the system performance on the Distributed Antenna System (DAS) is performed. A comparison for the system capacity between the closed building and the atrium building is conducted, showing that the former one benefits more when the number of the cells increases. The reason is the atrium cells suffer severe interference from neighbor cells during high traffic demand scenarios. Then some further cell configurations show that the number of the cells, the geometry performance and the balance of the user fraction should be considered to improve the system capacity.

Navigation and location technologies have been reaching in a major interest where Global Navigation Satellite System (GNSS) is mostly adopted. The limitation of this technology is that direct sky view is needed for reliable positioning. In indoor environments, however, it is difficult for GNSS technology to provide a reliable performance in positioning due to the signal attenuation and blocking caused by buildings and construction materials. For this reason, the growth in indoor applications has focused the research in new techniques for attempting mitigate the poor GNSS performance on this type of environments In the context of indoor positioning, multitude of emerging technologies for localization based on ultrasound, infrared, Ultra Wide Band (UWB), Zigbee, inertial navigation and other non-GNSS technologies have been proposed but special equipment is required and a large number of signal sources are needed. However, Wireless Local Area Network (WLAN) technology is widely used in indoor positioning. While the same requirements are also needed as the other technologies in order to improve the positioning accuracy, in terms of cost and ability, Wireless-based indoor location is widely used due to the already deployment of Anchor Points (AP) in urban and indoor areas. There are several methods for indoor positioning purposes e.g ToA (Time of Arrival), Received Signal Strength (RSS) measurements, AoA (Angle of Arrival), fingerprinting and so on. Most of the network-based location estimations use RSS measurements because almost all mobile devices are afforded to use this type of measurements. So, this thesis is centered in WLAN RSS-based positioning systems. The first step for indoor positioning is the distance estimation between the user and the AP. Theoretical and empirical propagation channel models are used to translate the difference between the transmitted and Received Signal Strength into an estimated range. A Propagation channel model built the radio map and also report changes in the environment. There are several models in the literature to characterize this channel. Indoor RSS-based localization has become a popular solution, but standard techniques still consider a time invariant simple single slope path loss channel model with a priori known constant channel parameters. While some contributions considered the RSS-based localization problem using a single path loss model with unknown parameters, the general solution that considersa generalized distance dependent measurement model is an important missing point. This thesis considers the two-slope channel model and proposes a robust indoor positioning solution based on a parallel architecture using a set of Interacting Multiple Models (IMM), each one involving two Extended Kalman filters (EKF) and dealing with the estimation of the distance to a given AP. Within each IMM, the two-slope path loss model parameters are sequentially estimated with Maximum Likelihood Estimate (MLE) to provide a robust solution. Finally, the set of distance estimates are fused into a standard EKF-based solution to mobile target tracking. In addition, the benchmarks derived in this thesis to evaluate the performance of our IMM-EKF algorithm are the Cramér Rao Lower Bound (CRLB) and the Posterior Cramér Rao Lower Bound (PCRLB) providing a guidance in the improvement of the experimental design. The CRLB is used to assess the estimation of model parameters and the PCRLB for tracking solution. This, combined with a path-loss exponent estimation, the channel calibration algorithm is validated with an online range estimation. The central theme throughout this thesis is to develop a completely online two-slope channel calibration and, simultaneously, a mobile target tracking algorithm. The performance of the method is assessed through realistic computer simulations and validated with real RSS measurements obtained from experimental tests in a typical office environment.
Las tecnologías en navegación y localización han estado obteniendo un gran interés en los últimos años donde el Sistema Global de Navegación por Satélite (GNSS) aparece como el más utilizado para estos fines. No obstante, una de las limitaciones del GNSS es la necesidad de tener una visión directa al cielo para así garantizar un posicionamiento bastante fiable. También, al utilizar solamente tecnología GNSS en espacios interiores (más conocidos en el mundo científico por entornos indoor), se es complicado conseguir un buen desempeño en términos de posicionamiento debido a la atenuación e interferencia de la señal causada por los edificios y materiales de construcción. Por esta razón, y debido al crecimiento en aplicaciones dentro de entornos indoor, la investigación de nuevas tecnologías para posicionamiento en interiores se ha centrado en intentar mitigar el mal desempeño de la tecnología GNSS en este tipo de ambientes. En el contexto de posicionamiento en interiores (indoor positioning), se han propuesto multitud de tecnologías emergentes para localización basadas en ultrasonido, infrarrojo, Banda Ultra Ancha (UWB), Zigbee,navegación inercial y otras tecnologías que no sean GNSS. Sin embargo, se requiere de equipo especial y un gran número de fuentes de señal. A pesar de ello, la tecnología en Redes de Área Local Inalámbricas (WLAN) es ampliamente utilizada en el posicionamiento en interiores. Aunque la tecnología WLAN tenga los mismos requerimentos que el resto de tecnologías, en términos de coste y practicidad, los sistemas de posicionamiento basados en redes inalámbricas se utilizan con mayor frecuencia debido al ya existente despliegue de estaciones base (AP) en áreas urbanas e interiores. Existen varias técnicas que sirven para fines de posicionamiento en interiores. Por ejemplo, utilizando el tiempo de llegada de la señal (TOA), las mediciones de la potencia de la señal recibida ( RSS), el ángulo de llegada (AoA), la técnica fingerprinting entre otras. Esta tesis está centrada en sistemas de posicionamiento basados en mediciones WLAN-RSS. Un modelo de canal de atenuación de interiores contruye un mapa de cobertura y también es capaz de reportar los cambios en el entorno indoor. El posicionamiento indoor basado en mediciones RSS se ha convertido en una solución bastante popular, pero las técnicas comunes consideran un modelo de pérdidas por trayectoria de una pendiente, invariante en el tiempo y con un conocimiento previo de los parámetros del canal que se consideran constantes. Esta tesis considera el modelo de pérdidas por trayectoria de pendiente dual y propone una solución robusta para posicionamiento en interiores basado en una arquitectura paralela conformada por un conjunto de algoritmos de Interacción de Múltiples Modelos (IMM) donde cada IMM involucra dos Filtros de Kalman Extendidos (EKF) para el proceso de estimación de la distancia entre el AP y el usuario. Dentro de cada IMM, los parametros del modelo de pérdidas por trayectoria de pendiente dual se estiman secuencialmente utilizando la estimación por máxima verosimilitud (MLE) y así proveer una solución robusta. Finalmente, el conjunto de distancias estimadas se fusionan en un EKF para tener una solución final de la posición del usuario. Además, las cotas de referencias que son derivadas en esta tesis y que sirven para evaluar el rendimiento del algoritmo IMM-EKF son la Cota Inferior de Cramér Rao (CRLB) y la Cota Inferior de Cramér Rao Posterior (PCRLB) que servirán de guía para el perfeccionamiento del diseño experimental. El tema central de esta tesis es desarrollar un algoritmo online para posicionamiento indoor que simultáneamente sea capaz de hacer la calibración del canal de propagación. El desempeño del método se evalúa mediante simulaciones por computadora que se validan con mediciones RSS reales obtenidas a partir de pruebas experimentales.

Large scale path loss modeling plays a fundamental role in designing both fixed and mobile radio systems. Predicting the radio coverage area of a system is not done in a standard manner. Wireless systems are expensive systems. Therefore, before setting up a system one has to choose a proper method depending on the channel environment, frequency band and the desired radio coverage range. Path loss prediction plays a crucial role in link budget analysis and in the cell coverage prediction of mobile radio systems. Especially in urban areas, increasing numbers of subscribers brings forth the need for more base stations and channels. To obtain high efficiency from the frequency reuse concept in modern cellular systems one has to eliminate the interference at the cell boundaries. Determining the cell size properly is done by using an accurate path loss prediction method. Starting from the radio propagation phenomena and basic path loss models this thesis aims at describing various accurate path loss prediction methods used both in rural and urban environments. The Walfisch-Bertoni and Hata models, which are both used for UHF propagation in urban areas, were chosen for a detailed comparison. The comparison shows that the Walfisch-Bertoni model, which involves more parameters, agrees with the Hata model for the overall path loss.

This work addresses the problem of digital terrain modelling for estimating radio path propagation within a mobile communication system. The ideal requirements are for a data structure which is storage efficient and computationally efficient for calculating profiles, whilst elevation errors should be constrained and radio path loss errors should be minimised. For a digital terrain model (DTM) to be considered viable as an alternative to the regular grid, it should: (i) produce a storage saving of at least 75% over the regular grid; (ii) be error constrained to a maximum absolute error of 10 metres; (iii) produce only a small overall average elevation error; (iv) preserve critical terrain characteristics such as ridges, peaks and slopes; (v) produce 95% of profiles to within a radio path loss error of ± 6 decibels; and (vi) be as computationally efficient as the regular grid. This research focuses on the implementation of a number of prototype DTMs, including a regular grid, sub-sampled grids, variable density grids, elevation difference grids, polynomial models of fixed and variable degree, surface patch quadtrees, and triangulated irregular networks (TINs). Each of these DTMs are examined in terms of the criteria outlined above. No DTM fulfils all of these requirements. The user should identify the relative importance of each requirement before selecting a specific model. For this study, computational efficiency is identified as the criterion which can be considered the least important. With this in mind, two original DTMs are developed. These are optimised with respect to storage and error constraints. The proposed Huffman-encoded DTM represents the deviations of a regular grid of heights from linearly predicted values as variable-length codes, whilst the Implicit TIN is a storage-efficient triangulated irregular network which reconstructs the original topology of the triangulation at the application stage. Both methods produce storage savings approaching 90% over the regular grid for the data sets tested and are suitable for parallel implementations.

The use of Ultra-Wideband (UWB) radio technology in a multistatic radar system has recently gained interest to implement Wireless Sensor Networks (WSN) capable of detecting and tracking targets in indoor environments. Due to the increasing attention towards multistatic UWB systems, it is important to perform the radio channel characterization. In this thesis we focus on the characterization of the path loss exponent (α). To perform the present work, the followed methodology was to collect experimental data from the UWB devices using a suitable target, this information was processed with a clutter removal algorithm using the Empty Room (ER) approach, then the contribution of the target was isolated to produce a graph of energy as a function of the product between the target-to-transmitter and the target-to-receiver distances in a bistatic configuration. Finally, using this plot it was properly obtained the value of the path loss exponent. As as additional experimental result, the main statistical parameters associated to the residual clutter were calculated, which are expected to allow having a better understanding and characterization of the radar system performance in the experimental environments.

The objective of this work is to enhance the awareness of the indoor propagation behaviour, by a set of investigations including simulations and measurements. These investigations include indoor propagation behaviour, local mean power estimation, proposing new indoor path loss model and introducing a case study on 60 GHz propagation in indoor environments using ray tracing and measurements. A summary of propagation mechanisms and manifestations in the indoor environment is presented. This comprises the indoor localization techniques using channel parameters in terms of angle of arrival (AOA), time of arrival (TOA) and received signal strength (RSS). Different models of path loss, shadowing and fast fading mechanisms are explored. The concept of MIMO channels is studied using many types of deterministic channel modelling such as Finite Difference Time Domain, Ray tracing and Dominant path model. A comprehensive study on estimating local average of the received signal strength (RSS) for indoor multipath propagation is conducted. The effect of the required number of the RSS data and their Euclidian distances between the neighbours samples are investigated over 1D, 2D and 3D configurations. It was found that the effect of fast fading was reduced sufficiently using 2D horizontal’s arrangement with larger spacing configuration. A modified indoor path loss prediction model is presented namely effective wall loss model (EWLM). The modified model with wall correction factors is compared to other indoor path loss prediction models using simulation data (for 2.4, 5, 28, 60 and 73.5 GHz) and real-time measurements (for 2.4 and 5 GHz). Different operating frequencies and antenna polarizations are considered to verify the observations. In the simulation part, EWLM shows the best performance among other models. Similar observations were recorded from the experimental results. Finally, a detailed study on indoor propagation environment at 60 GHz is conducted. The study is supported by Line of Sight (LoS) and Non-LoS measurements data. The results were compared to the simulated ones using Wireless-InSite ray tracing software. Several experiments have confirmed the reliability of the modelling process based on adjusted material properties values from measurements.

LoRaWAN is a wireless network technology based on the LoRa modulation technology. When planning such a network, it is important to estimate the network’s coverage, which can be done by calculating path loss. To do this, one can utilize empirical models of radio wave propagation. Previous research has investigated the accuracy of such empirical models for LoRa inside cities. However, as the accuracy of these models is heavily dependent on the exact characteristics of the environment, it is of interest to validate these results. In addition, the effect of base station elevation on the models’ accuracy has yet to be researched. Following the problems stated above, the purpose of this study is to investigate the accuracy of empirical models of radio wave propagation for LoRa in an urban environment. More specifically, we investigate the accuracy of the models and the effect of base station elevation on the models’ accuracy. The latter is the main contribution of this study. To perform these investigations, a quantitative experiment was conducted in the city of Jönköping, Sweden. In the experiment a base station was positioned at elevations of 30, 23, and 15m. The path loss was measured from 20 locations around the base station for each level of elevation. The measured path loss was then compared to predictions from three popular empirical models: the Okumura-Hata model, the COST 231-Walfisch-Ikegami model, and the 3GPP UMa NLOS model. Our analysis showed a clear underestimation of the path loss for all models. We conclude that for an environment and setup similar to ours, models underestimate the path loss by approximately 20dB. They can be improved by adding a constant correction value, resulting in a mean absolute error of at least 3,7-5,6dB. We also conclude that the effect of base station elevation varies greatly between different models. The 3GPP model underestimated the path loss equally for all elevations and could therefore easily be improved by a constant correction value. This resulted in a mean absolute error of approximately 4dB for all elevations.

This paper deals with the propagation of waves. Here is the wavelength distribution according to the wavelength. It focuses on the UHF and SHF band in which IEEE802.11n operates. Contains model breakdown by cell type. Describes which propagation methods are dominant in the cell type. Several propagation patterns are presented, which are then modeled in Matlab environment.The models are then compared to experimental measurements.

The diploma thesis describes mobile communication systems GSM and UMTS including the operating principle of these systems. It also deals with the GPS issues and the determination of the location by this system. The signal path losses issues between the transmitter and receiver are also described. The focus is also put on Telit UC864-G model and the measurement system, operated by the created programme with the graphic user interface, which measures parameters of the cellular network according to entered input parameters and saves the measured values into the file. The part of the diploma thesis describes another created programme with the graphic user interface displaying the measured network parameters in map data with the possibility to compare the distribution of the measured signal value in both outdoor and indoor environment and the theoretical value set by the propagation models.

L’évolution constante des technologies sans fil telles que le Wi-Fi, les normes de réseaux mobiles ou d’objets connectés, a donné naissance à de nouvelles applications et usages. Les possibilités offertes par cette multitude d’alternatives sont exploitées par les réseaux sans fil hétérogènes qui, en combinant au sein d’un réseau unique plusieurs technologies, permettent aux utilisateurs d’accéder à des services complémentaires de façon transparente. Cependant, pour bénéficier pleinement de ces avantages, plusieurs défis techniques sont à relever. L’un d’eux est relatif au déploiement de ces réseaux multi- technologies. En pratique, cette tâche s’appuie sur des règles et outils d’ingénierie afin de réaliser une planification optimale. Dans ce contexte, un objectif de la thèse a été d’établir des modèles sur lesquels peuvent se baser les outils d’ingénierie radio afin d’optimiser le déploiement de réseau locaux sans fil multi- technologies.Il s’agit principalement de calibrer des modèles de propagation pour l’estimation de couverture radio en environnement indoor résidentiel entre 800 MHz et 60 GHz; d’établir un modèle de débit pour l’estimation de capacité Wi-Fi en fonction du trafic montant et descendant; et de concevoir un modèle de résolution multi-objectif pour optimiser le positionnement de points d’accès opérant à 5 et 60 GHz. En complément, cette thèse a également proposé des recommandations pratiques visant à placer au mieux les points d’accès en phase de déploiement. Cela s’est fait par le biais d’études de sensibilité de couverture à divers facteurs, tels que l’environnement immédiat de l’émetteur ou encore la présence de personnes faisant obstruction
The constant evolution of wireless technologies such as Wi-Fi, mobile networks standards or IoT, has given rise to new applications and usages. The possibilities offered by this multitude of alternatives are exploited by heterogeneous wireless networks which, by combining within a single network several technologies, provide the users with a seamless access to complementary services. However, to take full advantage of these benefits, there are several technical issues to address. One of them is related to the deployment of these multi-technology networks. In practice, this task relies, most of the time, on radio network design software to achieve optimal planning. In such context, the main objective of this thesis is to establish models which can be used by radio network planning tools in order to the deployment of multi-technology wireless local area networks. This task has involved calibrating propagation models for radio coverage estimation, in residential indoor environments from 800 MHz to 60 GHz; developing a throughput model for Wi-Fi capacity estimation based on uplink and downlink traffic; and establishing a multi- objective resolution model to optimize the positioning of access points operating at 5 and 60 GHz. Moreover, this thesis also proposes practical recommendations for a better positioning of access points during deployment phases. This task has been achieved through coverage sensitivity studies to various factors, such as the transmitter surroundings or the presence of obstructing people

At present, the current 4G systems provide a universal platform for broadband mobile services; however, mobile traffic is still growing at an unprecedented rate and the need for more sophisticated broadband services is pushing the limits on current standards to provide even tighter integration between wireless technologies and higher speeds. This has led to the need for a new generation of mobile communications: the so-called 5G. Although 5G systems are not expected to penetrate the market until 2020, the evolution towards 5G is widely accepted to be the logical convergence of internet services with existing mobile networking standards leading to the commonly used term “mobile internet” over heterogeneous networks, with several Gbits/s data rate and very high connectivity speeds. Therefore, to support highly increasing traffic capacity and high data rates, the next generation mobile network (5G) should extend the range of frequency spectrum for mobile communication that is yet to be identified by the ITU-R. The mm-wave spectrum is the key enabling feature of the next-generation cellular system, for which the propagation channel models need to be predicted to enhance the design guidance and the practicality of the whole design transceiver system. The present work addresses the main concepts of the propagation channel behaviour using ray tracing software package for simulation and then results were tested and compared against practical analysis in a real-time environment. The characteristics of Indoor-Indoor (LOS and NLOS), and indoor-outdoor (NLOS) propagations channels are intensively investigated at four different frequencies; 5.8 GHz, 26GHz, 28GHz and 60GHz for vertical polarized directional, omnidirectional and isotropic antennas patterns. The computed data achieved from the 3-D Shooting and Bouncing Ray (SBR) Wireless Insite based on the effect of frequency dependent electrical properties of building materials. Ray tracing technique has been utilized to predict multipath propagation characteristics in mm-wave bands at different propagation environments. Finally, the received signal power and delay spread were computed for outdoor-outdoor complex propagation channel model at 26 GHz, 28 GHz and 60GHz frequencies and results were compared to the theoretical models.

[ES] La población mundial en países desarrollados está envejeciendo y con ello existe un aumento de enfermedades en gran medida causadas por la edad. Las nuevas tecnologías médicas pueden ayudar a detectar, diagnosticar y tratar estas enfermedades y con ello ahorrar dinero, tiempo y recursos de los sistemas sanitarios. Las tecnologías inalámbricas implantables han abierto un nuevo panorama para la próxima generación de tecnologías médicas. Frecuencias como la Ultra Wide-Band (UWB) de 3.1 a 10.6 GHz están siendo consideradas para la nueva generación de dispositivos inalámbricos para dentro del cuerpo humano. Las características como el reducido tamaño de las antenas, la baja potencia de transmisión y la alta velocidad de datos son las más buscadas en este tipo de dispositivos. El problema surge porque el cuerpo humano depende de la frecuencia de modo que a mayores frecuencias, mayores son las pérdidas por propagación. Conociendo el canal de transmisión se puede solventar el problema de las altas pérdidas. Esta tesis tiene como objetivo caracterizar el canal de radio frecuencia (RF) para la nueva generación de dispositivos médicos implantables. Para caracterizar el canal se han empleado tres diferentes metodologías: simulaciones numéricas, medidas en phantom y experimentos en animales vivos. Las medidas en phantom fueron realizadas en un nuevo sistema de medidas expresamente disen¿ados para medidas de dentro a fuera del cuerpo humano en la banda de frecuencias UWB. Además, se utilizó un novedoso recipiente con dos capas de phantom imitando la zona gastrointestinal del cuerpo. Estos phantoms fueron creados para este tipo de medidas y son extremadamente precisos a las frecuencias UWB. Para los experimentos en animales se utilizaron cerdos y se intentó reproducir en ellos las medidas previamente realizadas en phantom. Las simulaciones software se realizaron con la intención de replicar ambas metodologías. Una vez realizados los experimentos se realizó un extensivo estudio del canal en dominio frecuencial y temporal. Mas en detalle, se compararon las antenas usadas en la recepción y transmisión, el efecto de la grasa en el canal, la formas del recipiente contenedor de phantom y las componentesmulticamino. Como resultado se ha propuesto un modelo de propagación del canal para la banda baja de las frecuencias UWB (3.1 -5.1 GHz) para la zona gastrointestinal del cuerpo humano. Este modelo de propagación ha sido validado utilizando las tres metodologías previamente descritas y comparada con otros estudios existentes en literatura. Finalmente, se midió el canal de propagación para una determinada aplicación a bajas frecuencias con señales UWB. También se realizaron medidas del canal de propagación en la zona cardíaca del cuerpo humano desde un punto de vista de seguridad de datos. Los resultados obtenidos en esta tesis confirman los beneficios que tendría la utilización de frecuencias UWB para las futuras generaciones de dispositivos médicos implantables.
[CA] La població mundial a països desenvolupats està envellint-se i enfrontant-se a un augment d'infermetats principalment causades per la edat. Les noves tecnologies mèdiques poden ajudar a detectar, diagnosticar i tractar aquestes malalties, estalviant diners, temps i recursos sanitaris. Els dispositius implantables sense fils han generat un nou panorama per a les noves generacions de dispositius mèdics. Les freqüències com la banda de UWB estan sent considerades per a les futures tecnologies implantables. La reduïda grandària de les antenes, la baixa potència de transmissió i les altes velocitats de dades son característiques buscades per als dispositius implantables. Per contra, els éssers humans depenen de la freqüència en el sentit que a majors freqüències, majors les pèrdues per propagació quan el senyal travessa el cos humà d'interior a exterior. Per solventar aquestes pèrdues el canal de propagació s'ha d'entendre i conèixer de la millor manera possible. Aquesta tesi doctoral te com a objectiu caracteritzar el canal de radio freqüència (RF) per a la nova generació de dispositius mèdics implantables. S'han emprat tres metodologies diferents per a realitzar aquesta caracterització: simulacions software, mesures amb fantomes i experiments amb animals vius. Els experiments amb fantomes es van realitzar a un sistema de mesures dissenyat expressament per a les transmissions de dins a fora del cos humà a les freqüències UWB. També es van utilitzar un contenidor per als fantomes de dues capes, imitant l'area gastrointestinal dels humans. Per als experiments a animals es van emprar porcs, replicant els experiments al laboratori en fantomes de la forma més semblant possible. Les simulacions software foren dissenyades per a imitar les experiments amb fantomes i animals. Després dels experiments el canal de propagació es va investigar exhaustivament des del domini freqüèncial i temporal. S'ha observat com les antenes en transmissió i recepció afecten al senyal, la influència de la grassa, la forma del contenidor de fantoma i les possibles contribucions multicamí. Finalment es proposa un nou model de propagació per a les baixes freqüències UWB (3.1 a 5.1 GHz) per a la zona GI del cos humà. El model es va validar utilitzant les tres metodologies abans esmentades i també foren comparades amb model ja existents a la literature. Finalment des d'un punt de vista aplicat, el canal es va avaluar per al senyal UWB a baixes freqüències (60 MHz). A més a més, per a la nova generació de marcapassos sense fil es va investigar el canal des d'un punt de vista de seguretat de dades. Els resultats obtinguts a aquesta tesi confirmen els avantatges d'emprar la banda de freqüències UWB per a la nova generació de dispositius médics implantables.
[EN] The current global population in developed countries is becoming older and facing an increase in diseases mainly caused by age. New medical technologies can help to detect, diagnose and treat illness, saving money, time, and resources of physicians. Wireless in-body devices opened a new scenario for the next generation of medical devices. Frequencies like the Ultra Wide-band (UWB) frequency band (3.1 - 10.6 GHz) are being considered for the next generation of in-body wireless devices. The small size of the antennas, the low power transmission, and the higher data rate are desirable characteristics for in-body devices. However, the human body is frequency ependent, which means higher losses of the radio frequency (RF) signal from in- to out-side the body as the frequency increases. To overcome this, the propagation channel has to be understood and known as much possible to process the signal accordingly. This dissertation aims to characterize the (RF) channel for the future of in-body medical devices. Three different methodologies have been used to characterize the channel: numerical simulations, phantom measurements, and living animals experiments. The phantom measurements were performed in a novel testbed designed for the purpose of in-body measurements at the UWB frequency band. Moreover, multi-layer high accurate phantoms mimicking the gastrointesintal (GI) area were employed. The animal experiments were conducted in living pigs, replicating in the fairest way as possible the phantom measurement campaigns. Lastly, the software simulations were designed to replicate the experimental measurements. An in-depth and detail analysis of the channel was performed in both, frequency and time domain. Concretely, the performance of the receiving and transmitting antennas, the effect of the fat, the shape of the phantom container, and the multipath components were evaluated. Finally, a novel path loss model was obtained for the low UWB frequency band (3.1 - 5.1 GHz) at GI scenarios. The model was validated using the three methodologies and compared with previous models in literature. Finally, from a practical case point of view, the channel was also evaluated for UWB signals at lower frequencies (60 MHz) for the GI area. In addition, for the next generation of leadless pacemakers the security link between the heart and an external device was also evaluated. The results obtained in this dissertation reaffirm the benefits of using the UWB frequency band for the next generation of wireless in-body medical devices.
Pérez Simbor, S. (2019). In-body to On-body Experimental UWB Channel Characterization for the Human Gastrointestinal Area [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/133034
TESIS

Made available in DSpace on 2014-12-17T14:55:43Z (GMT). No. of bitstreams: 1 GustavoAC__DISSERT.pdf: 2594771 bytes, checksum: b46a4c0b026ad559d9ed126acb92b471 (MD5) Previous issue date: 2010-07-09
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The telecommunications industry has experienced recent changes, due to increasing quest for access to digital services for data, video and multimedia, especially using the mobile phone networks. Recently in Brazil, mobile operators are upgrading their networks to third generations systems (3G) providing to users broadband services such as video conferencing, Internet, digital TV and more. These new networks that provides mobility and high data rates has allowed the development of new market concepts. Currently the market is focused on the expansion of WiMAX technology, which is gaining increasingly the market for mobile voice and data. In Brazil, the commercial interest for this technology appears to the first award of licenses in the 3.5 GHz band. In February 2003 ANATEL held the 003/2002/SPV-ANATEL bidding, where it offered blocks of frequencies in the range of 3.5 GHz. The enterprises who purchased blocks of frequency were: Embratel, Brazil Telecom (Vant), Grupo Sinos, Neovia and WKVE, each one with operations spread in some regions of Brazil. For this and other wireless communications systems are implemented effectively, many efforts have been invested in attempts to developing simulation methods for coverage prediction that is close to reality as much as possible so that they may become believers and indispensable tools to design wireless communications systems. In this work wasm developed a genetic algorithm (GA's) that is able to optimize the models for predicting propagation loss at applicable frequency range of 3.5 GHz, thus enabling an estimate of the signal closer to reality to avoid significant errors in planning and implementation a system of wireless communication
O setor de telecomunica??es vem passando por grandes transforma??es, devido ao aumento da busca por acesso a servi?os digitais de transmiss?o de dados, v?deo e multim?dia, especialmente, por meios das redes de telefonia m?vel. Recentemente, no Brasil, as operadoras de telefonia m?vel v?m atualizando suas redes para sistemas de terceira gera??o (3G) proporcionando aos usu?rios servi?os em banda larga como v?deo confer?ncia, Internet e TV digital, dentre outros. Essas novas redes que proporcionam mobilidade e elevadas taxas de transmiss?o t?m permitido o desenvolvimento de novos conceitos de mercado de servi?os. Atualmente o mercado est? voltado para a expans?o da tecnologia WiMAX, que v?m ganhando cada vez mais o mercado das comunica??es m?veis de voz e de dados. No Brasil o interesse comercial para esta tecnologia aparece com a primeira outorga de licen?as em 3,5 GHz. Em fevereiro de 2003, a ANATEL realizou a licita??o 003/2002/SPV-ANATEL, onde ofereceu blocos de frequ?ncia em 3,5 GHz. As operadoras que adquiriram os blocos de frequ?ncia foram: Embratel, Brasil Telecom (Vant), Grupo Sinos, Neovia e WKVE, cada uma com opera??es distribu?das em regi?es do Brasil. Para que esse e outros sistemas de comunica??es sem fio sejam implementados com efici?ncia, muitos esfor?os t?m sido investidos na tentativa de desenvolvimento de m?todos de simula??o, de predi??o e de cobertura que se aproximem da realidade o melhor poss?vel, de forma a que se possam tornar ferramentas fi?is e indispens?veis no planejamento dos sistemas de comunica??es sem fio. Neste trabalho, foi desenvolvido um algoritmo gen?tico (AG s) capaz de otimizar os modelos de predi??o de perda de propaga??o aplic?veis na frequ?ncia de 3,5 GHz, possibilitando dessa forma uma estimativa do sinal mais pr?xima da realidade, evitando erros significativos no planejamento e implementa??o de um sistema de comunica??o sem fio

No
Narrowband path loss measurements are reported for the vehicle-to-vehicle channel between a transmitting antenna 50 cm above the ground and a car-roof-mounted receiver array. Calibration procedures and measurement results are reported for typical urban, suburban and rural-motorway environments and compared with existing mobile channel models to give insight into the large-scale fading behavior in the vehicle-to-vehicle channel.

Yes
A modified indoor path loss prediction model is presented, namely Effective Wall Loss Model (EWLM). The modified model is compared to other indoor path loss prediction models using simulation data and real-time measurements. Different operating frequencies and antenna polarizations are considered to verify the observations. In the simulation part, EWLM shows the best performance among other models as it outperforms two times the dual slope model which is the second-best performance. Similar observations were recorded from the experimental results. Linear attenuation and one slope models have similar behaviour, the two models parameters show dependency on operating frequency and antenna polarization.
The full-text of this article will be released for public view at the end of the publisher embargo on 3 Oct 2018.

碩士
淡江大學
電機工程學系碩士班
103
With the prosperous development of smart phones new smart phone applications constantly emerge in the daily life. Whenever there is a new application of smart phone introduced in the market it will always generate pro and con heated discussions. Following the development of BLE (Bluetooth Low Energy) Bluetooth related applications also become a hot topic at the present time and the study of applying Bluetooth in the indoor positioning has also appeared in many research fields. In this paper, we make field measurement of the path loss in the Bluetooth wireless transmission path and also in the measurement including obstacles and human blockings to investigate their effect on the wireless signal transmission so as to establish an accurate positioning methodology. 　　In this paper, we use MATLAB program to create a GUI interface. The user can choose the test scenario that he would like to review, and then the program will automatically plot the path loss curves for the selected test scenario and will mark the test data points; and consequently from the plotted curves the user can make the decision to determine the distance between the transmitter and receiver being a near-range, mid-range or a long-range and then this information will be used as reference when using Bluetooth as a positioning technique.

碩士
國立東華大學
電機工程學系
106
The current status of spectrum usage has been an uneven allocation, so we are in more urgent need of Cognitive Radio (CR) which is proposed to probing for spectrum holes to effectively make unlicensed users access the licensed bands so the idle periods of spectrum can be cut down. Hence, the spectrum bands will be effectively utilized. In this thesis, WINNER II path loss model is applied as an example for the simulation of wireless system. By using the antenna diversity, the cooperative spectrum sensing observes the probabilities of false alarm and detection between the primary user and cognitive relays. Then, a relay-assisted method over cognitive relays is applied to enhance the received signals in fusion center so that some signals in cognitive relays farther from fusion center can be relayed through the nearer cognitive relays and the overall bit error rate in fusion center can be improved. Finally, the decision fusion with different rules including AND, OR and Majority is applied to improve the accuracy of decision fusion.

In urban rail transit, systems using communication based train control (CBTC), it uses high accuracy of train locating, realizes a continuous automatic train control system. High resolution of locating the train permits the high line capacity and fewer Infrastructures is required than Track circuit based system therefore all over the world countries have more concerned about this technology. DCS system plays an important role in the information interaction between ground equipment and vehicle equipment in CBTC. DCS is WLAN which is short range radio networks based on IEEE 802.11, complete communication network is built with many closely deployed AP (Access Point). IEEE 802.11b is a physical layer amendment for operation in the 2.4 GHz band, adopted in CBTC system in which data transmits at 11Mbps and uses DSSS modulation. Data communications systems based in the 2.4 GHz ISM band has raised the concern of RF interference between CBTC equipped trains and the variety of new and existing users of this band. The reliability and safety of information transmission can be improved when leaky waveguide is used as transmission medium of train-ground wireless communication in CBTC (Communication Based Train Control), also it can provide better performance and stronger anti-interference ability than free space. These benefits of leaky waveguide insisting the research scholar of communication field to intervene in CBTC system. Wireless LAN technologies are adopted in most train wayside communication systems in CBTC. Successful handoff plays an indispensable role in wireless communications. Running through the large wireless networks with numerous APs in urban mass transit, a train equipped with CBTC systems inevitably encounters the problems of handoff. Against the possibly negative phenomena such as Ping-Pong effect, handoff delay, packet loss and so on. Frequency Combination and Location based Handover scheme are analysed, both handover scheme are also correlated with Leaky waveguide based CBTC system. After analysis, it is realized that Location Based Handover Scheme is best suited for Leaky waveguide based CBTC system in many aspects. Leaky waveguide also limits the implementation of various handover schemes.

[ES] La quinta generación de comunicaciones móviles, 5G, promete ser una revolución tecnológica que vaya más allá de multiplicar la velocidad de transmisión de datos de sus predecesoras. Pretende soportar una gran cantidad de dispositivos y alcanzar latencias muy cercanas a 1 milisegundo. Para satisfacer estos ambiciosos requisitos, se han investigado nuevas tecnologías habilitadoras. Una de ellas es el uso de las bandas de ondas milimétricas (mmW) en las cuales hay una gran cantidad de espectro disponible. Para predecir las características del canal radio y evaluar las prestaciones de la 5G de forma fiable en las bandas mmW se requieren modelos de canal complejos. Concretamente, los modelos de propagación más precisos son los basados en trazado de rayos, pero su alto costo computacional los hacen inviables para la caracterización del canal radio en escenarios complejos. Por otro lado, en los últimos años, la tecnología de videojuegos ha desarrollado potentes herramientas para modelar la propagación de la luz en escenarios superrealistas. Dada la cercanía espectral entre el espectro visible y las ondas mmW, la presente Tesis ha estudiado la aplicación de las herramientas de modelado de propagación de la luz de los motores de juego para el modelado del canal radio en mmW. Esta Tesis propone un modelo de estimación de las pérdidas de propagación en mmW llamado "Modelo de Intensidad de Luz'' (LIM). Usando este modelo, basado en los procesos de iluminación realizados por los motores de juego, los transmisores de señal se sustituyen por focos de luz y la intensidad lumínica recibida en un punto se traduce a potencia de señal en milimétricas a través de una función polinómica sencilla. Una de las ventajas de usar los motores de juego es su gran capacidad y la facilidad que tiene el usuario para crear escenarios superrealistas que representen fielmente la geometría de escenarios donde se quiera evaluar el canal radio. De esta forma se pueden obtener estimaciones precisas de las pérdidas de propagación. La estimación de las pérdidas de propagación con LIM ha sido comparada con campañas de medida en las bandas de 28 GHz y 73 GHz y con otros modelos de propagación. Como resultado, el error de estimación de LIM es menor que los modelos estocásticos actuales y es comparable con el modelo de trazado de rayos. Y, además, el coste computacional de LIM comparado con el trazado de rayos es 130 veces menor, lo que posibilita el uso de LIM en escenarios altamente complejos para la estimación del canal radio en tiempo real. Los motores de juego permiten caracterizar de forma diferente la interacción de los materiales con la luz configurando el mapa de normales de sus superficies y sus funciones de dispersión y reflexión. En esta Tesis se ha determinado la caracterización de varios materiales que mejor se ajusta a medidas de laboratorio realizadas en un escenario controlado en la banda de 28 GHz. El modelo de LIM empleando materiales con esta caracterización óptima reduce más de un 50\% su error de estimación con respecto a la aplicación de LIM con los materiales por defecto, mientras que su coste computacional sigue siendo 26 veces menor que el modelo de trazado de rayos. Finalmente, se ha desarrollado sobre un motor de juego una primera versión de plataforma para la emulación de los sistemas 5G que es el punto de partida para un emulador completo de 5G. Esta plataforma no sólo contiene el modelo de LIM sino que incluye varios casos de uso de la 5G en entornos superrealistas. La plataforma, que se basa en el concepto de "Serious Game Engineering", rompe las limitaciones de los simuladores de redes móviles en cuanto a las capacidades de visualización e interacción del usuario con los componentes de la red en tiempo real.
[CAT] La cinquena generació de comunicacions mòbils, 5G, promet ser una revolució tecnològica que vaja més enllà de multiplicar la velocitat de transmissió de dades de les seues predecessores. Pretén suportar una gran quantitat de dispositius i aconseguir latències molt pròximes a 1 mil·lisegon. Per a satisfer aquests ambiciosos requisits, s'han investigat noves tecnologies habilitadores. Una d'elles és l'ús de les bandes d'ones mil·limètriques (mmW) en les quals hi ha una gran quantitat d'espectre disponible. Per a predir les característiques del canal ràdio i avaluar les prestacions de la 5G de forma fiable en les bandes mmW es requereixen models de canal complexos. Concretament, els models de propagació més precisos són els basats en traçat de rajos, però el seu alt cost computacional els fan inviables per a la caracterització del canal ràdio en escenaris complexos. D'altra banda, en els últims anys, la tecnologia de videojocs ha desenvolupat potents eines per a modelar la propagació de la llum en escenaris superrealistes. Donada la proximitat espectral entre l'espectre visible i les ones mmW, la present Tesi ha estudiat l'aplicació de les eines de modelatge de propagació de la llum dels motors de joc per al modelatge del canal radie en mmW. Aquesta Tesi proposa un model d'estimació de les pèrdues de propagació en mmW anomenat "Model d'Intensitat de Llum'' (LIM). Usant aquest model, basat en els processos d'il·luminació realitzats pels motors de joc, els transmissors de senyal se substitueixen per focus de llum i la intensitat lumínica rebuda en un punt es tradueix a potència de senyal en mil·limètriques a través d'una funció polinòmica senzilla. Una dels avantatges d'usar els motors de joc és la seua gran capacitat i la facilitat que té l'usuari per a crear escenaris superrealistes que representen fidelment la geometria d'escenaris on es vulga avaluar el canal ràdio. D'aquesta forma es poden obtindre estimacions precises de les pèrdues de propagació. L'estimació de les pèrdues de propagació amb LIM ha sigut comparada amb campanyes de mesura en les bandes de 28~GHz i 73~GHz i amb altres models de propagació. Com a resultat, l'error d'estimació de LIM és menor que els models estocàstics actuals i és comparable amb el model de traçat de rajos. I, a més, el cost computacional de LIM comparat amb el traçat de rajos és 130 vegades menor, la qual cosa possibilita l'ús de LIM en escenaris altament complexos per a l'estimació del canal ràdio en temps real. Els motors de joc permeten caracteritzar de forma diferent la interacció dels materials amb la llum configurant el mapa de normals de les seues superfícies i les seues funcions de dispersió i reflexió. En aquesta Tesi s'ha determinat la caracterització de diversos materials que s'ajusta millor a mesures de laboratori realitzades en un escenari controlat en la banda de 28 GHz. El model de LIM emprant materials amb aquesta caracterització òptima redueix més d'un 50 % el seu error d'estimació respecte a l'aplicació de LIM amb els materials per defecte, mentre que el seu cost computacional continua sent 26 vegades menor que el model de traçat de rajos. Finalment, s'ha desenvolupat sobre un motor de joc una primera versió de plataforma per a l'emulació dels sistemes 5G que és el punt de partida per a un emulador complet de 5G. Aquesta plataforma no solament conté el model de LIM sinó que inclou diversos casos d'ús de la 5G en entorns superrealistes. La plataforma, que es basa en el concepte de "Serious Game Engineering", trenca les limitacions dels simuladors de xarxes mòbils quant a les capacitats de visualització i interacció de l'usuari amb els components de la xarxa en temps real.
[EN] The fifth generation of mobile communications, 5G, promises to be a technological revolution that goes beyond multiplying the data transmission speed of its predecessors. It aims to support a large number of devices and reach latencies very close to 1 millisecond. To meet these ambitious requirements, new enabling technologies have been researched. One of these is the use of millimetre-wave bands (mmW) in which a large amount of spectrum is available. Complex channel models are required to predict radio channel characteristics and reliably evaluate 5G performance in the mmW bands. Specifically, the most accurate propagation models are those based on ray tracing, but their high computational cost makes them unfeasible for radio channel characterization in complex scenarios. On the other hand, in recent years, video game technology has developed powerful tools to model the propagation of light in super realistic scenarios. Given the spectral closeness between the visible spectrum and the mmW waves, the present Thesis has studied the application of light propagation modeling tools from game engines for radio channel modeling in mmW. This Thesis proposes a model for estimating propagation losses in mmW called "Light Intensity Model'' (LIM). Using this model, based on the lighting processes performed by the game engines, the signal transmitters are replaced by light sources and the light intensity received at a point is translated into signal strength in mmW through a simple polynomial function. One of the advantages of using the game engines is their great capacity and the ease with which the user can create super realistic scenarios that faithfully represent the geometry of scenarios where the radio channel is to be evaluated. In this way, accurate estimates of propagation losses can be obtained. The estimation of propagation losses with LIM has been compared with measurement campaigns in the 28 GHz and 73 GHz bands and with other propagation models. As a result, the LIM estimation error is smaller than the current stochastic models and is comparable with the ray tracing model. In addition, the computational cost of LIM compared to ray tracing is 130 times lower, allowing the use of LIM in highly complex scenarios for real-time radio channel estimation. The game engines allow to characterize in a different way the interaction of the materials with the light configuring the normal map of their surfaces and their scattering and reflection functions. In this Thesis it has been determined the characterization of several materials that best fits to laboratory measurements made in a controlled scenario in the 28 GHz band. The LIM model using materials with this optimal characterization reduces by more than 50% its estimation error with respect to the application of LIM with default materials, while its computational cost remains 26 times lower than the ray tracing model. Finally, a first version of a platform for the emulation of 5G systems has been developed on a game engine, which is the starting point for a complete 5G emulator. This platform not only contains the LIM model but also includes several 5G use cases in super realistic environments. The platform, which is based on the concept of "`Serious Game Engineering", breaks the limitations of mobile network simulators in terms of visualization capabilities and user interaction with network components in real time.
Inca Sánchez, SA. (2019). Serious Game Engineering and Lighting Models for the Realistic Emulation of 5G Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/132695
TESIS

Radio network planning needs proper channel characterization and hence approximation of path loss propagation is its key aspect. Path loss is a phenomenon that happens due to the attenuation suffered by the signal as the propagation over the transmitting medium. Wireless systems deployment is expensive; therefore, path loss models propagate dare necessary for the predicting signal strength received(RSS) at the transmitter from a given distance; estimation of radio coverage areas of Base Transceiver Stations (BTS); frequency tests; interference analysis, without conducting huge propagation measurements which are time taking and costly. Thus, predicting the path loss is critical to properly address the lack of signal strength at various places within the coverage region. Empirical path loss prediction models such as Okumura-Hata, COST-231-Hata are less sensitive to change in physical geometry like environmental structures; local terrain profiles; and weather conditions of the site. Artificial Intelligence came to the fore in understanding the past data to make future predictions and is suggested as an alternative approach in this field. In this work, propagation quantities like transmitting to receiving antennas distance, transmitted power and elevation of terrain, clutter height, latitude and longitude are used as inputs to develop path loss model based on AI techniques such as Multi-Layer Perceptron (MLP), Radial Basis Function (RBF)and Adaptive Neuro-Fuzzy Inference Systems (ANIFS)to predict the path loss in macro cell environment. The performance of these AI based models is compared with widely followed HATA model. The experimental results are provided on the recently released dataset containing the RSS values of GSM network working at 900 MHz and 1800 MHz. Mean Square Error (MSE) and R-square fit is achieved between the reading values and the outputs of model as a performance measure. ANFIS model’s performed better compared to other AI models in the prediction of path loss as it is the hybrid model which utilize the advantages of neuro-fuzzy.

Kriging is proposed as a tool for Wi-Fi signal strength estimation for complex indoor environments. This proposal is based on two studies suggesting that kriging might be suitable for this application. Both of these studies have shortcomings in supporting this proposal, but their results encourage a more in depth investigation into this. Even though kriging is a geostatistical method developed for geographical interpolation, it has been used successfully in a wide range of other applications as well. This further suggests that kriging might be a versatile method to overcome some of the difficul- ties of existing signal strength estimation methods. Two main types of signal strength estimation are deterministic methods and empirical methods. Deterministic methods are generally very complex and requires input parameters that are difficult to obtain. Empirical methods are known to have low accuracy which makes them unreliable for practical use. Three main investigations are presented in order to evaluate the use of kriging for this application. A sampling plan is proposed as part of a generic application protocol for the practical use of kriging for Wi-Fi signal strength. It is concluded that kriging can be conffidently used as an estimation technique for Wi-Fi signal strength in complex indoor environments. Kriging is recommended for practical applications, especially where in- sufficient information is available about a building or where time consuming site surveys are not feasible.
MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Στις σύγχρονες τηλεπικοινωνίες, χρησιμοποιείται μια μεγάλη γκάμα από RF μοντέλα, για τον υπολογισμό την μέσης τιμής ισχύος του σήματος εκπομπής για δεδομένη απόσταση από τον πομπό και για δεδομένη συχνότητα. Στις διεργασίες αυτές , επιδρούν στο δικό τους βαθμό διάφορες παράμετροι τοπολογικού (πληθυσμός , τύπος εμποδίων, πυκνότητα εμποδίων) και γεωγραφικού (μορφολογία εδάφους, υγρασία, διαμόρφωση χώρου) χαρακτήρα, αλλά και χαρακτηριστικά των πομποδεκτών ( συνήθως το ύψος και το κέρδος των κεραιών). Στις περισσότερες περιπτώσεις οι απώλειες όδευσης (Path Loss όπως είναι γνωστές στη διεθνή βιβλιογραφία) , εκφράζονται σε dB , σα συνάρτηση της συχνότητας λειτουργίας του υπό μελέτη συστήματος και της απόστασης ανάμεσα στον πομπό και το δέκτη ( πάντα για δεδομένα χαρακτηριστικά κεραιών και τύπο περιβάλλοντος). Έτσι μια ντετερμινιστική γνώση του μέσου path loss, που σε συνδυασμό με άλλες πιθανές απώλειες μας δίνει το σύνολο των απωλειών είναι εφικτή. O περιορισμός όσον αφορά στη συχνότητα και στις αποστάσεις , έχουν οδηγήσει τη σύγχρονη έρευνα στην επέκταση των υπαρχόντων μοντέλων , τόσο εξωτερικού όσο και εσωτερικού χώρου. Μια βασική παράμετρος της έρευνας στηρίζεται στην παραδοχή πως ο νόμος του αντιστρόφου τετραγώνου , ο οποίος περιγράφεται από την εξίσωση του Friis δε βρίσκει εφαρμογή, παρά μόνο σε περιβάλλοντα όπου επιτυγχάνεται LOS( Line of Sight) όδευση. Η τροποποίηση της παραπάνω εξίσωσης με δυναμικό ως προς το εκάστοτε περιβάλλον τρόπο , επιτρέπει πλέον τον υπολογισμό της μέσης ισχύος του σήματος σε σχετικά ρεαλιστικό βαθμό. Για παράδειγμα έχει προταθεί τροποποίηση με την τρίτη δύναμη της απόστασης για ένα σύνολο εφαρμογών , που αφορούν συστήματα ασυρμάτων τηλεπικοινωνιών εξωτερικού περιβάλλοντος.Ένα εσωτερικό περιβάλλον απαιτεί μια πολύ πιο ντετερμινιστική φόρμουλα υπολογισμού των απωλειών ώστε να μπορέσει ο μελετητής να υπολογίσει με αξιοπιστία την ισχύ του σήματος σε μια δεδομένη θέση. Η ακρίβεια λοιπόν των μοντέλων εξαρτάται άμεσα από την ικανότητά τους να απεικονίσουν και να αποδώσουν με τη σειρά τους , μέσω των υπολογισμών, όλα αυτά τα σύνθετα φαινόμενα με τον καλύτερο δυνατό τρόπο. Η πλειοψηφία των RF μοντέλων που αναπτύσσονται στα πλαίσια ακόλουθων παραγράφων, έχει αναπτυχθεί και αξιολογηθεί για συστήματα κυτταρικής κινητής τηλεφωνίας (GSM, PCS-1800, GPRS, UMTS). Προκειμένου να ξεπεραστούν διάφοροι περιορισμοί των αρχικών μοντέλων ως προς την συχνότητα λειτουργίας του συστήματος και την απόσταση πομπού-δέκτη (ουσιαστικά την εμβέλεια του μοντέλου), ορισμένες προεκτάσεις έχουν παρουσιαστεί σε διάφορες ερευνητικές εργασίες και χρησιμοποιούνται ευρέως . Ορισμένα νέα μοντέλα έχουν επίσης προστεθεί στα ήδη υπάρχοντα για τις συχνότητες συστημάτων κινητής τηλεφωνίας . Για άλλες περιοχές συχνοτήτων με έντονο ενδιαφέρον, πχ στα 5,2 GHz, διάφορες προτάσεις έχουν πραγματοποιηθεί, συχνά υποστηριζόμενες από μετρήσεις. Λαμβάνοντας υπόψη την συχνότητα των 2,4 GHz, δεν μπορούμε παρά να συμπεράνουμε ότι η όσο το δυνατόν πιο ακριβής και επιστημονικά αξιόπιστη μοντελοποίηση του ασύρματου διαύλου, ιδιαίτερα – άλλα όχι αποκλειστικά – για τοπολογίες εσωτερικών χώρων, είναι πολύ σημαντική για τον σχεδιασμό και την εύρυθμη λειτουργία των Wi-Fi συστημάτων και των WLAN δικτύων. Παρόλα αυτά, αν και στην υπάρχουσα βιβλιογραφία και στην διεθνή επιστημονική και ερευνητική κοινότητα υπάρχουν αρκετά σημαντικές εργασίες για την μοντελοποίηση του ασύρματου διαύλου στα 2,4 GHz , εντούτοις απουσίαζε, για πολύ καιρό, μία ολοκληρωμένη συγκριτική αντιπαραβολή και αξιολόγηση των βασικών θεωρητικών μοντέλων για τον υπολογισμό της μέσης απώλειας οδεύσεως στη συγκεκριμένη συχνότητα. Στα πλαίσια της εργασίας αυτής , θα προσπαθήσουμε να αξιοποιήσουμε το σύνολο των μετρήσεων και των δεδομένων που συλλέξαμε , σε ρεαλιστικές συνθήκες και για πραγματικά συστήματα μετάδοσης , τόσο να αξιολογήσουμε τα ήδη υπάρχοντα RF μοντέλα , όσο και να προβούμε στις απαραίτητες προτάσεις και τροποποιήσεις όπου αυτό κριθεί σκόπιμο. Επίσης για τη σκίαση επιχειρούμε εδώ μια προσέγγιση υπολογισμού μέσω της χρήσης των RF μοντέλων και την ενσωμάτωση όλων των χαρακτηριστικών διάδοσης , που αφορούν και στα δύο στοιχεία των μεγάλης κλίμακας διαλείψεων. Οι μετρήσεις μέσης λαμβανόμενης ισχύος πραγματοποιήθηκαν σε πέντε διαφορετικές τοπολογίες. Σε κάθε μία από αυτές τις τοπολογίες ελήφθησαν μετρήσεις της μέσης λαμβανόμενης ισχύος σε διάφορες δειγματοληπτικές αποστάσεις πομπού-δέκτη ούτως ώστε να είναι εφικτή, με έναν υψηλό βαθμό αξιοπιστίας, η αξιολόγηση των βασικών μοντέλων απωλειών οδεύσεως. Ταυτόχρονα, μέσα από αυτή την διαδικασία, αξιολογήθηκε η αξιοπιστία των μοντέλων αναφορικά με τις ιδιαιτερότητες της κάθε τοπολογίας, που αποτυπώνονται ποιοτικά και ποσοτικά στους μηχανισμούς διάδοσης του ραδιοσήματος σε κάθε περίπτωση.
In modern wireless communications, a wide range of RF models are used to provide the median (average) value of the signal strength at a given distance from the transmitter and for a given frequency spectrum. In this procedure, certain geographical (ground, humidity, terrain irregularities), topological (heavy or scattered population, type of obstacles, density of the buildings) characteristics of the area, as well as certain specifications of the transmitter and receiver antennas (most notably antenna height and antenna gain) have to be taken into consideration. In most cases, the mean value of the path loss is expressed in dB in dependence with the frequency of the operating system and the distance between the transmitter and the receiver (for given antenna characteristics and a certain type of environment where the system operates). Thus, a deterministic knowledge of the average path loss (which along with the average rain loss and diffraction loss provides the overall propagation loss in dB) is available. However, distance and frequency limitations have led research to a further study and expanding of the existing empirical and semi-empirical models , for both outdoor and indoor scenarios. A fundamental parameter-based study of the path loss models is based on the concept that the second power law that is predicted by the Friis equation does not apply in real-life scenarios except for standard LOS paths. The modified power law research allows engineers and scholars to calculate the mean received power of a signal transmitted over a wireless link in a more realistic approach. It has been suggested that the third-power law is more suitable for a plethora of applications based on wireless communications for an outdoor environment.The indoor propagation channel, in particular, demands a lot more than a deterministic formula of calculating the average signal strength as a function of distance and frequency. The increased impact of multipath and other propagation phenomena such as reflection and scattering, as well as the existence of many objects whose proportions are comparatively close to the wavelength of the operating wireless systems, render the propagation of a signal and its arrival at a receiver (mobile or fixed) a rather complex procedure. The precision of the path loss models depends heavily on their ability to demonstrate and reflect, in the calculations, these complex phenomena to the best possible way .The majority of these models have been developed and validated for mobile telephony systems in both outdoor and indoor schemes (GSM, PCS-1800, GPRS, UMTS). Certain extensions of many of these models were conducted in order to expand the frequency and distance limitation of the original formulas. New empirical models have also been suggested for these certain frequencies .Taking into account the very sensitive and subject to many different factors nature of the indoor propagation channel, it is easily concluded that both researchers in academia and engineers in industry need to have reliable models that will predict precisely the average path loss over the indoor 2.4 GHz channel which is of utter importance as the de facto frequency of Wi-Fi and WLAN systems. A gap in aforementioned research, however, is that it either concentrates on multipath parameters or does not feature a full comparative validation of most well-known indoor path loss models.The purpose of this work is to present, all the data collected through experiments in realistic conditions and real telecom systems, in order to validate and modify (where necessary) the existing RF models. Furthermore an empirical formula to measure attenuation due to shadowing is derived through these RF models.Measurements took part in five different topologies. In each of them the mean received power was recorded, for various distances between the transmitter and the receiver, in order for our endeavor to validate the RF models in question to be reliable. Through this procedure, RF models where examined towards each topology’s distinctive characteristics that reflect in quality and quantity all the attenuation mechanisms that affect the propagated signal.