Multi agent system (MAS) is considered an effective way to design, analyze and implement complex systems in various disciplines nowadays. However, MAS has not been sufficiently applied in mainstream modelling of wireless communication networks yet. The exponential growth of network users has led today’s communication networks even more significantly complex. As such, modelling and simulation tends to grow in proportion but not markedly to meet the preciseness and complexity of the system under consideration. Furthermore, the future mobile communication seems to incline over self-adaptive resource allocation and congestion control mechanisms. This aims to relieve the workload of the network operator while maintaining the QoS level of the communication intact. The advancements also envision the autonomous nature of future wireless communication technologies where dynamic resource allocation will play a vital role in efficient bandwidth utilization, throughput maximization and effective power control mechanisms. In this context, MAS brings about various possibilities to model and simulate environments which are typically stochastic in nature and tends to grow in a decentralized manner. MAS based simulation is such a simulation method which has gained recognition in modeling telecommunication systems where issues like network complexity, traffic and network management are prevalent. MAS has its proven standing to represent a real interactive environment of a system where learning, negotiation and cooperation are important phenomena. On that account, MAS has already started to establish its turf in the wireless communication systems as well. As a matter of fact, the existing network simulators are not designed to incorporate the features that MAS has to offer. So, the agent based simulation toolkits are used alongside, on top of which most of the physical environment aspects can be modeled that are usually neglected by the existing network simulators. This thesis investigates the areas of wireless communications where multi agent systems and simulators are applicable by the means of literature study and presents simple simulation models constructed in Netlogo, a multi agent based simulation toolkit. As a result, the applicability of MAS simulators in areas like radio channel environment, resource allocation, routing, medium access control and cognitive radio is presented. At the end, conclusions are drawn about feasibility of using MAS simulators to simulate wireless communication networks.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2008. Includes bibliographical references (leaves 67-72). / Distributed wireless sensor networks (DWSNs) are applied in a variety of applications that can enhance the quality of human life or even save lives, such as in fire monitoring, where DWSN microsensors relay the exact location of the fire to water sprinkler actors to automatically extinguish the fire. Batteries are currently the predominant source of energy in DWSNs. one of the key obstacles in the adoption of DWSN technology is the limited lifetime of batteries in microsensors. Recharging or replacing depleted batteries can significantly increase costs in DWSNs. The aim of this study is to address the power challenge in DWSNs by proposing a sixteen-element equiangular spiral rectenna to ahrvest ambient microwave energy to supply indoor DWSNs. The study concludes that this rectenna model has the potential to generate power that enables long periods of operation of the DWSNs without human intervention in the power manageement process, thus reducing maintenance and administration costs. The efficiency of the rectenna model was tested in an anechoic chamber. Efficiency test results indicated that the highest efficiency of 2% for the rectenna model was achieved as 2 GHz for an ambient power of -6 dBm across a 1 K ohm load resistence. The study further concludes that the current rectenna model size of sixteen elements is a limiting factor for the deployment of DWSNs.

Orientador: Paulo Cardieri / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-23T21:03:39Z (GMT). No. of bitstreams: 1 Nardelli_PedroHenriqueJuliano_D.pdf: 1436293 bytes, checksum: cb00e855f5094f65e4ad9f206f58cfd1 (MD5) Previous issue date: 2013 / Resumo: O Resumo poderá ser visualizado no texto completo da tese digital / Abstract: The complete Abstract is available with the full electronic document / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Magister Scientiae - MSc / This thesis proposed and presented technical details of new probabilistic metrics of trust in the links wireless ad hoc networks for unobservable communications. In covert communication networks, only the end nodes are aware of the communication characteristics of the overall path. The most widely used protocols of ad hoc networks was overviewed. The routing protocols of ad hoc networks with trust considerations and select Destination Sequence Routing, a protocol that can be used in distributed ad hoc network settings for path discovery, was also reviewed. It establishes a path through which all packets sent by a source must pass to the destination. The end nodes are responsible for examining the statistics of the received packets and deriving inferences on path feature variations which are used for computing new trust metrics. When a path is judged not trustworthy based on the metrics, the Destination Sequence Routing is informed to undertake a new trusted path discovery between the end points. The thesis added a new feature based on the quality of service parameters of the path to create trust in the links in recognition of attacks. / South Africa

This work deals with the fundamental principles of wireless communications in mobile robotics. It introduces overview of the use of different frequency bands for wireless communications needs and control of mobile devices in Czech Republic. It also contains a brief overview of all applicable technologies and available modules that can be used for wireless communication. The theoretical part deals with some of the protocols that were used in the practical part of this work and the manner of wave propagation in buildings. The practical part consisted of a design of our own application to monitor and control the module Mikrotik Routerboard. With this application we have tested and compared two wireless cards of this module.

Optical wireless communication (OWC) offers many benefits over established radio frequency–based communication links. Particularly in, high-data services, high security, and license-free operation, OWC link are becoming an attractive solution for the next generation of communication systems. In OWC, precise alignment of the incoming beam is necessary to close the communication link. However, precisely aligning the beam between the transceivers is challenging due to the laser beam’s narrowness and external disturbances that can significantly reduce, destroy, or scatter the beam signal. Therefore, designing optimized control strategies can significantly improve the alignment precision, which is the main motivation for this work. This thesis deploys standard and optimal control techniques, with an emphasis on optimized control strategies, to address the alignment problem in underwater optical wireless communication (UOWC) and in laser beam stabilizer systems within a vibrating environment. First, the UOWC system’s alignment problem was investigated in a vibrating scenario. For its effective control, the properties of light propagation were considered by accounting for the dynamical model that describes the propagation characteristics of the signal beam between transceivers. To control the UOWC system, we designed an observer-based optimal controller approach that combined the unconstrained and constrained optimal controllers, namely linear quadratic regulator (LQR) and model predictive control (MPC) with the extended Kalman filter (EKF). The latter enabled estimations of the beam dynamics from the power of the received beam signal. Extensive simulation tests were conducted that demonstrated the efficiency of the MPC algorithm compared to the LQR, fractional order proportional integral derivative (FOPID) and conventional PID controllers in terms of tracking and robustness against the disturbance levels. Second, the alignment problem in the laser beam stabilizer system was considered, whereby the designed control algorithms were tested experimentally in a vibrating disturbance. For this particular system, the LQR and MPC optimal controllers were designed both in simulation and experimental environments. The designed optimal control algorithms were compared to a conventional PID controller and its optimized variants (e.g., fractional and robust), demonstrating the MPC design’s outperformance in terms of tracking error and robustness to different voltage disturbance levels.

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Modern radar and communication systems have experienced a tremendous increase in the number of antennas onboard, on the ground, and in orbital space. This places a burden due to the confined volume and limited weight requirements especially in space applications. The reconfigurable antenna is a promising and exciting new type of antenna, where through the use of appropriate switches the antenna can be structurally reconfigured, to maintain the elements near their resonant dimensions for several frequency bands. This increases the bandwidth of the antenna dramatically, which enables the use of one antenna for several applications. Four novel reconfigurable antenna elements were designed to work at 2.45 GHz and at 5.78 GHz, to cover the transition period when wireless communication will shift to the 5.78 GHz band. The four elements designed are: the reconfigurable Yagi, the reconfigurable corner-fed triangular loop antenna, the reconfigurable center-fed equilateral triangular loop antenna and the reconfigurable rectangular-spiral antenna. None of these antennas have been reported in the literature. Simulation results for all four antennas were obtained using IE3D. Fabrication and measurements for the Yagi antenna was done and the measured results agree with simulations. All four antennas have very good performance with respect to the 3dB beamwidth and directivity. However the reconfigurable rectangular-spiral antenna is the most compact in size among all four antennas. It is (20 mm x 20 mm) in size. At 2.45 GHz it has a 3dB beamwidth of 87° and directivity of 6.47dB. As for the 5.78GHz frequency the 3dB beamwidth is 82.5° and the directivity is 7.16dB. This dissertation also introduces the use of reconfigurable antenna elements in adaptive arrays. An adaptive array that can null interference and direct its main lobe to the desired signal while being reconfigurable to maintain functionality at several frequency bands has the potential to revolutionize wireless communications in the future. Through several examples, at both the design frequencies, it is shown that the reconfigurable and adaptive antenna arrays are successful in nulling noises incident on the array. These examples illustrate how reconfigurable elements and adaptive arrays can be combined very beneficially for use in wireless communication systems.

Yes / A type of telecommunication technology called an ultra-wideband (UWB) is used to provide a typical solution for short-range wireless communication due to large bandwidth and low power consumption in transmission and reception. Printed monopole antennas are considered as a preferred platform for implementing this technology because of its alluring characteristics such as light weight, low cost, ease of fabrication, integration capability with other systems, etc. Therefore, a compact-sized ultra-wideband (UWB) printed monopole antenna with improved gain and efficiency is presented in this article. Computer simulation technology microwave studio (CSTMWS) software is used to build and analyze the proposed antenna design technique. This broadband printed monopole antenna contains a jug-shaped radiator fed by a coplanar waveguide (CPW) technique. The designed UWB antenna is fabricated on a low-cost FR-4 substrate with relative permittivity of 4.3, loss tangent of 0.025, and a standard height of 1.6 mm, sized at 25 mm × 22 mm × 1.6 mm, suitable for wireless communication system. The designed UWB antenna works with maximum gain (peak gain of 4.1 dB) across the whole UWB spectrum of 3–11 GHz. The results are simulated, measured, and debated in detail. Different parametric studies based on numerical simulations are involved to arrive at the optimal design through monitoring the effects of adding cuts on the performance of the proposed antennas. Therefore, these parametric studies are optimized to achieve maximum antenna bandwidth with relatively best gain. The proposed patch antenna shape is like a jug with a handle that offers greater bandwidth, good gain, higher efficiency, and compact size.