The master‘s thesis is focused on data transfer over power lines. The influence of connected devices on data signal is studied. In this thesis, you can find the descriptions of PLC technology characteristics, sources of signal interruption and, mainly, the method of modelling the PLC channels as a multipath signal propagation environment is thoroughly discussed. There are models of PLC channels using this method projected in Simulink. The analysis of the influence of connected devices to bit error rate of a signal is processed. The devices are modelled by connected impedance.

Les Réseaux de Capteurs Sans Fils (RCSFs) ont pris beaucoup d'importance dans plusieurs domaines tels que l'industrie, l'armée, la pollution atmosphérique etc. Les capteurs sont alimentés par des batteries qui ne sont pas faciles à remplacer surtout dans les environnements peu accessibles. L'énergie de chaque capteur est considérée comme la source première d'augmentation de la durée de vie des RCSFs. Puisque la transmission de données est plus coûteuse en consommation d'énergie, notre préoccupation première est de proposer une technique efficace de transmission des données de tous les capteurs vers le sink tout en réduisant la consommation en énergie. Nous suggérons trois trois algorithmes d'agrégation de données basé sur la construction d'arbres : Depth-First Search Aggregation (DFSA), Flooding Aggregation (FA) et Well-Connected Dominating Set Aggregation (WCDSA) qui permettront de réduire le nombre de transmissions de chaque capteur vers le sink. L'agrégation des données basée sur la construction d'arbres souffre du délai de délivrance de données parce que les parents doivent attendre de recevoir les données de leurs feuilles. Certains parents pourraient avoir beaucoup de feuilles, et il serait alors assez coûteux pour un parent de stocker toutes les données entrantes dans sa mémoire. Ainsi, nous devons déterminer le temps que chaque parent doit mettre pour agréger et traiter les données de ses feuilles. Nous proposons un algorithme, Efficient Tree-based Aggregation and Processing Time (ETAPT) qui utilise la métrique Appropriate Data Aggregation and Processing Time (ADAPT). Etant donné la durée maximale acceptable, l'algorithme ETAPT prend en compte la position des parents, le nombre de feuilles et la profondeur de l'arbre pour calculer l'ADAPT optimal. A n'importe quel moment pendant l'agrégation des données par les parents, il peut arriver que la quantité de données collectées soit très grande et dépasse la quantité de stockage maximale de données que peut contenir leurs mémoires. Nous proposons l'introduction dans le réseau de plusieurs collecteurs de données appelés Mini-Sinks (MSs). Ces MSs sont mobiles et se déplacent selon un modèle de mobilité aléatoire dans le réseau pour maintenir la connexité afin d'assurer la collecte contrôlée des données basée sur le protocole de routage Mulipath Energy Conserving Routing Protocol (MECRP). Les capteurs peuvent être équipés de plusieurs interfaces radios partageant un seul canal sans fil avec lequel ils peuvent communiquer avec plusieurs voisins. La transmission des données à travers une liaison de communication entre deux parents peut interférer avec les transmissions d'autres liaisons si elles transmettent à travers le même canal. Nous avons besoin de savoir quel canal utiliser en présence de plusieurs canaux pour une transmission donnée. Nous proposons une méthode distribuée appelée: Well Connected Dominating Set Channel Assignement (WCDS-CA), pour calculer le nombre de canaux qui seront alloués à tous les capteurs de telle sorte que les capteurs adjacents se voient attribués des canaux différents / Wireless Sensor Networks (WSNs) have gained much attention in a large range of technical fields such as industrial, military, environmental monitoring etc. Sensors are powered by batteries, which are not easy to replace in harsh environments. The energy stored by each sensor is the greatest impediment for increasing WSN lifetime. Since data transmission consumes more energy, our major concern is how to efficiently transmit the data from all sensors towards a sink. We suggest three tree-based data aggregation algorithms: Depth-First Search Aggregation (DFSA), Flooding Aggregation (FA) and Well-Connected Dominating Set Aggregation (WCDSA) to reduce the number of transmissions from each sensor towards the sink. Tree-based data aggregation suffers from increased data delivery time because the parents must wait for the data from their leaves. Some parents might have many leaves, making it very expensive for a parent to store all incoming data in its buffer. We need to determine the aggregation time each parent in the tree has to spend in aggregating and processing the data from its leaves. We propose an Efficient Tree-based Aggregation and Processing Time (ETAPT) algorithm using Appropriate Data Aggregation and Processing Time (ADAPT) metric. Given the maximum acceptable latency, ETAPT's algorithm takes into account the position of parents, their number of leaves and the depth of the tree, in order to compute an optimal ADAPT time. At any time, the amount of data aggregated by parents may become greater than the amount of data that can be forwarded. We propose the introduction into the network of many data aggregators called Mini-Sinks (MSs). MSs are mobile and move according to a random mobility model inside the sensor field to maintain the fully-connected network in order to aggregate the data based on the controlled Multipath Energy Conserving Routing Protocol (MECRP). Sensors may use many radio interfaces sharing a single wireless channel, which they may use to communicate with several neighbours. Two sensors operating on the same wireless channel may interfere with each other during the transmission of data. We need to know which channel to use in the presence of multiple channels for a given transmission. We propose a distributed Well-Connected Dominating Set Channel Assignment (WCDS-CA) approach, in which the number of channels that are needed over all sensor nodes in the network in such a way that adjacent sensor nodes are assigned to distinct channels.

Multi-antenna communication systems are attracting research interest as a means to increase the information capacity, reliability, and spectral efficiency of wireless information transfer. Ray-tracing methods predict the behavior of wireless channels using a model of the propagation environment and are a low-cost alternative to direct measurements. We use ray tracing simulations to validate the statistical time and angle of arrival characteristics of an indoor multipath channel and compare model parameter estimates with estimates derived from channel sounding measurements. Ray tracing predicts the time and angle clustering of multipaths observed in the measurements and provides model parameter estimates which are closely correlated with measured estimates. The ray tracing parameters relating to power characteristics show more deviation from measurements than the time and angle related parameters. Our results also indicate that the description of reflective scatterers in the propagation environment is more important to the quality of the predicted statistical behavior than the description of bulk materials. We use a ray synthesis model to investigate means of efficiently representing the channel for feedback information to the transmitter as a means to increase the information capacity. Several methods of selecting the ray-model feedback information are demonstrated with results from simulated and measured channels. These results indicate that an ESPRIT algorithm coupled with ad hoc transmit/receive pairing can yield better than 90% of the ideal waterfilling capacity when adequate training-based channel estimates are available. Additionally, we investigate a covariance feedback method for providing channel feedback for increased capacity. Both the ray-based and covariance-based feedback methods yield their highest capacity improvements when the signal to noise ratio is low. This results because of the larger benefit of focusing transmit power into the most advantageous eigenmodes of the channel when fewer eigenmodes have power allocated to them by the waterfilling capacity solution. In higher signal to noise ratio cases, more eigenmodes of the channel receive power when waterfilling, and the capacity improvement from feedback information decreases relative to a uniform power allocation. In general, ray model feedback methods are preferable because the covariance feedback quickly requires higher computational effort as the array sizes increase and typically results in lower capacity for a given amount of feedback information.

This thesis describes the application of adaptive equalization based on the constant modulus algorithm (CMA) and the decision-feedback minimum mean squared error (DF-MMSE) concept to the two compatible offset QPSK waveforms (FQPSK and SOQPSK-TG) that constitute the ARTM Tier-1 waveforms. An adaptive version of the DF-MMSE equalizer is developed and applied to this application. In the presence of frequency selective multipath interference typically encountered in aeronautical telemetry, both equalization techniques are shown to provide reliable performance for FQPSK and SOQPSK-TG. The performance of both waveforms with the DF-MMSE equalizer is slightly better than that using the CMA equalizer. Implementation trade-offs between the two types of equalizers are discussed.

Yes / The issue of asset tracking in dense environments where the performance of the global positioning system (GPS) becomes unavailable or unreliable is addressed. The proposed solution uses a low-profile array of antenna elements (sensors) mounted on a finite conducting ground. A compact-size sensor array of six electrically small dual-band omnidirectional spiral antenna elements was designed as a front end of a tracker to operate in the 402 and 837 MHz spectrum bands. For the lower band, a three-element superposition method is applied to support estimation of the angle of arrival (AOA), whereas all six sensors are employed for the higher band. A low complexity and accurate AOA determination algorithm is proposed, the projection vector (PV), and this is combined with the array mentioned. Orthogonal frequency division multiplexing (OFDM) is integrated with the PV technique to increase the estimation resolution. The system was found to be suitable for installation on the roof of vehicles to localize the position of assets. The proposed system was tested for the tracking of nonstationary sources, and then two scenarios were investigated using propagation modeling software: outdoor to outdoor and outdoor to indoor. The results confirm that the proposed tracking system works efficiently with a single snapshot. / European Union Horizon 2020 Research and Innovation Program; 10.13039/501100009928 - Higher Committee for Education Development (HCED), Iraq

No description available.

Multipath error is a source of uncertainty within GNSS (Global Navigation Satellite System) where signals are reflected on various surfaces before they reach the receiver. The phenomenon causes a delay in the receiver when the reflected signal travels a longer distance than the direct one. Despite the fact that there is a good knowledge of the error, multipath effects are still a complex subject since its origin varies a lot. This has led to a number of different methods being developed for the purposes to distinguish and treat the error. The main goal of this study is to investigate the size and distribution of multipath errors and to present which satellites contributes to the most multipath effects meanwhile evaluating the existence of possible reflective objects. As a result, static measured coordinates are also analyzed against coordinates from a real-time measurement in order to study possible connections related to multipath errors. The study is based on observations measured over 16 points on the green area in front of house 45 at the University of Gävle. Furthermore, data processing and analysis are performed in the open software RTKlib with associated program extensions. The result of the study shows that multipath errors have an influence on GNSS-measurements over the survey area and that these errors vary in centimeters to a decimeter level in mean value and RMS for all points. Furthermore, it also appears from the study that satellites that are at higher elevation also emit signals containing multipath errors. In addition, it may be noted that signals even at higher elevation masks contribute to multipath errors over the points where points 2, 3 and 12 are most affected. Furthermore, signals from the satellites R10, R11, R19, R20 and G15 contain high multipath on both L1 and L2 frequencies. Possible sources of reflections was estimated over the area for points 2, 3 and 12 from the correlation between high multipath errors and direction towards the investigation area. / Flervägsfel är en osäkerhetskälla inom GNSS (Global Navigation Satellite System) där signalerna reflekteras innan de når mottagaren. Fenomenet orsakar en fördröjning hos mottagaren då den reflekterade signalen färdas en längre sträcka än den direkta. Trots att det idag finns en god kännedom kring felkällan är flervägsfel fortsatt komplex eftersom dess ursprung är väldigt varierande. Detta har medfört att en rad olika metoder tagits fram för experimentella ändamål inom området. Syftet med denna studie är att undersöka storlek och fördelning av flervägsfel samt visa på vilka satelliter som bidrar mest till effekterna av felkällan samtidigt som eventuella reflekterande objekt utvärderas. I följd av detta analyseras även efterberäknade koordinater mot koordinater från en realtidsmätning för att om möjligt kunna studera eventuella samband relaterat till flervägsfel. Studien grundar sig på observationer mätta med statisk metod över 16 punkter på gräsytan framför hus 45 vid Högskolan i Gävle. Vidare utförs databehandling och analyser i den öppna programvaran RTKlib med tillhörande programtillägg. Resultatet av undersökningen visar att flervägsfel har en påverkan på GNSS-mätningar över undersökningsområdet och att dessa fel varierar på centimeter till decimeternivå i medelvärde och RMS för samtliga punkter. Vidare framgår det också av undersökningen att satelliter som befinner sig vid högre elevationsmask också avger signaler innehållande flervägsfel. Som slutsats kan det konstateras att signaler även vid högre elevationsmask bidrar till flervägsfel över punkterna där punkterna 2, 3 och 12 är högst påverkade. Vidare innehåller signaler från satelliterna R10, R11, R19, R20 och G15 högt flervägsfel på både L1 och L2 frekvensen. Möjliga reflektionsobjekt uppskattades över området för punkterna 2, 3 och 12 från sambandet mellan högt flervägsfel samt riktning mot undersökningsområdet.

This dissertation presents research performed in the areas of radio wave propagation measurement and modeling, smart antenna arrays, and software-defined radio development. A four-channel, wideband, software-defined receiver was developed to serve as a test bed for wideband measurements and antenna array experiments. This receiver was used to perform vector channel measurements in terrestrial and air-to-ground environments using an antenna array. ent results served as input to radio channel simulations based on three geometric channel models. The simulation results were compared to measurement results to evaluate the performance of the radio channel models under test. Criteria for evaluation include RMS delay spread, excess delay spread, signal envelope fading, antenna diversity gain, and gain achieved through the use of a two-dimensional rake receiver. This research makes contributions to the wireless communications field through analysis, development, measurement, and simulation that builds upon past theoretical and experimental results. Contributions include a software-defined radio architecture, based on object oriented techniques, that has been developed and successfully demonstrated using the wideband receiver. This research has produced new wideband vector channel measurements to provide extensive characterization results facilitating simulation of emerging wireless technology for commercial and military communications systems. Original ways of interpreting multipath component strength and correlation for antenna arrays have been developed and investigated. A novel geometric air-to-ground ellipsoidal channel model has been developed, simulated, and evaluated. Other contributions include an evaluation of two popular radio channel models, a geometric channel simulator for producing channel impulse responses, and analytical derivation results related to channel modeling geometries and multipath channel measurement processing. In addition to new results, existing theory and earlier research results are discussed. Fundamental theory for antenna arrays, vector channels, multipath characterization, and channel modeling is presented. Contemporary issues in software radio and object orientation are described, and measurement results from other propagation research are summarized. / Ph. D.

Wireless sensor networks (WSNs) are frequently deployed unattended and can be easily captured or compromised. Once compromised, intrusion prevention methods such as encryption can no longer provide any protection, as a compromised node is considered a legitimate node and possesses the secret key for decryption. Compromised nodes are essentially inside attackers and can perform various attacks to break the functionality of the system. Thus, for safety-critical WSNs, intrusion detection techniques must be used to detect and remove inside attackers and fault tolerance techniques must be used to tolerate inside attackers to prevent security failure. In this dissertation research, we develop a class of dynamic redundancy management algorithms for redundancy management of multisource multipath routing for fault and intrusion tolerance, and majority voting for intrusion detection, with the goal of maximizing the WSN lifetime while satisfying application quality-of-service and security requirements, for base station based WSNs, homogeneous clustered WSNs, and heterogeneous clustered WSNs. By means of a novel model-based analysis methodology based on probability theory, we model the tradeoff between energy consumption vs. reliability, timeliness and security gain, and identify the optimal multisource multipath redundancy level and intrusion detection settings for maximizing the lifetime of the WSN while satisfying application quality-of-service requirements. A main contribution of our research dissertation is that our dynamic redundancy management protocol design addresses the issues of "how many paths to use" and "what paths to use" in multisource multipath routing for intrusion tolerance. Another contribution is that we take an integrated approach combining intrusion detection and tolerance in the protocol design to address the issue of "how much intrusion detection is enough" to prevent security failure and prolong the WSN lifetime time. We demonstrate resiliency of our dynamic redundancy management protocol design for intrusion detection and tolerance against sophisticated attacker behaviors, including selective and random capture, as well as persistent, random, opportunistic and insidious attacks, by model-based performance analysis with results supported by extensive simulation based on ns3. / Ph. D.

As developments in wireless ad hoc networks continue, there is an increasing expectation with regard to supporting content-rich multimedia communications (e.g., video) in such networks, in addition to simple data communications. The recent advances in multiple description (MD) video coding have made it highly suitable for multimedia applications in such networks. In this thesis, we study three important problems regarding multiple description video communications in wireless ad hoc networks. They are multipath routing for MD video, MD video multicast, and joint routing and server selection for MD video in wireless ad hoc networks. In multipath routing for MD video problem, we follow an applicationcentric cross-layer approach and formulate an optimal routing problem that minimizes the application layer video distortion. We show that the optimization problem has a highly complex objective function and an exact analytic solution is not obtainable. However, we find that a metaheuristic approach such as Genetic Algorithms (GAs) is eminently effective in addressing this type of complex cross-layer optimization problems. We provide a detailed solution procedure for the GA-based approach, as well as a tight lower bound for video distortion. We use numerical results to compare this approach to several other approaches and demonstrate its superior performance. In MD video multicast problem, we take the similar application-centric, cross-layer approach as in the multipath routing problem. We propose an MD video multicast scheme where multiple source trees are used. Furthermore, each video description is coded into multiple layers in order to cope with diversity in wireless link bandwidths. Based on this multicast model, we formulate the multicast routing as a combinatorial optimization problem and apply Genetic Algorithm (GA)-based metaheuristic procedure to solove this problem. Performance comparisons with existing approaches show significant gains for a wide range of network operating conditions. In the last problem, we study the important problem of joint routing and server selection for MD video in ad hoc networks. We formulate the task as a combinatorial optimization problem and present tight lower and upper bounds for the achievable distortion. The upper bound also provides a feasible solution to the formulated problem. Our extensive numerical results show that the bounds are very close to each other for all the cases studied, indicating the near-global optimality of the derived upper bounding solution. Moreover, we observe significant gains in video quality achieved by the proposed approach over existing server selection schemes. This justifies the importance of jointly considering routing and server selection for optimal MD video streaming in wireless ad hoc networks. / Master of Science